阅读说明：本技术 拖拉机的行驶传动装置 (Driving transmission device of tractor ) 是由 薗田俊介 辻贤一朗 武本博贵 于 2020-04-02 设计创作，主要内容包括：前轮离合器(40)及前轮增速离合器(60)被前轮传动轴(29)支承。在前轮离合器(40)与前轮增速离合器(60)之间,具备支承前轮传动轴(29)的支架(70B)。跨支架(70B)和前轮传动轴(29)穿设有第1操作油路(91),所述第1操作油路(91)对前轮离合器(40)进行切换操作。跨支架(70B)和前轮传动轴(29)穿设有第2操作油路(94),所述第2操作油路(94)对前轮增速离合器(60)进行切换操作。(The front wheel clutch (40) and the front wheel speed increasing clutch (60) are supported by the front wheel transmission shaft (29). A bracket (70B) for supporting the front wheel transmission shaft (29) is provided between the front wheel clutch (40) and the front wheel speed increasing clutch (60). A1 st operation oil path (91) penetrates through the cross support (70B) and the front wheel transmission shaft (29), and the 1 st operation oil path (91) performs switching operation on the front wheel clutch (40). A2 nd operation oil path (94) penetrates through the cross support (70B) and the front wheel transmission shaft (29), and the 2 nd operation oil path (94) performs switching operation on the front wheel speed increasing clutch (60).)

1. A running transmission device of a tractor is characterized in that,

the disclosed device is provided with:

a front wheel differential mechanism for transmitting power to the left and right front wheels;

a rear wheel differential mechanism for transmitting power to the left and right rear wheels; and

a transmission to which power of a power source is input and which transmits the input power to the front wheel differential mechanism and the rear wheel differential mechanism;

the transmission comprises:

a front wheel transmission shaft for transmitting power to the front wheel differential mechanism;

a front wheel clutch which can be switched between an engaged state in which power is transmitted to the front wheel propeller shaft and a disengaged state in which power transmission to the front wheel propeller shaft is disengaged, and which transmits power to the front wheel propeller shaft in a state in which an average circumferential speed of the left and right front wheels is equal to an average circumferential speed of the left and right rear wheels in the engaged state; and

a front wheel speed increasing clutch which can be switched between an engaged state in which power is transmitted to the front wheel propeller shaft and a disengaged state in which power transmission to the front wheel propeller shaft is disengaged, and which transmits power to the front wheel propeller shaft in a state in which the average circumferential speed of the left and right front wheels is faster than the average circumferential speed of the left and right rear wheels in the engaged state;

the front wheel clutch and the front wheel speed-up clutch are supported by the front wheel transmission shaft in a state of being arranged in the axial direction of the front wheel transmission shaft;

a bracket that rotatably supports the front wheel transmission shaft is provided between the front wheel clutch and the front wheel speed increasing clutch;

a 1 st operation oil path is arranged across the front wheel transmission shaft and the bracket in a penetrating manner, and the 1 st operation oil path carries out switching operation on the front wheel clutch;

and a 2 nd operation oil path is arranged across the front wheel transmission shaft and the bracket in a penetrating manner, and the 2 nd operation oil path carries out switching operation on the front wheel speed increasing clutch.

2. The travel transmission of a tractor according to claim 1,

the bracket includes a support part which is fitted to a rotating member of the front wheel speed increasing clutch so as to be relatively rotatable and supports the rotating member;

a bearing is interposed between the rotating member and the support portion.

3. Running gear of a tractor according to claim 1 or 2,

a transmission case for accommodating the transmission;

the bracket is supported by a wall portion of the transmission case in a state of being formed separately from the transmission case;

a 2 nd carrier that rotatably supports the front wheel transmission shaft at a position located on the opposite side of the front wheel clutch from the front wheel speed increasing clutch;

the 2 nd bracket is supported by a wall portion of the transmission case other than the wall portion in a state of being formed separately from the transmission case.

4. The travel transmission of a tractor according to claim 3,

and a spacer connected to a portion of the bracket that is offset from the wall portion and a portion of the 2 nd bracket that is offset from the other wall portion, and configured to set a distance between the bracket and the 2 nd bracket.

5. The running gear of a tractor according to any one of claims 1 to 4,

a 1 st biasing member that biases the front wheel clutch to the engaged state;

a 1 st hydraulic piston provided in the front wheel clutch, and operated by the hydraulic pressure supplied from the 1 st operation oil passage to operate the front wheel clutch to the disengaged state against the 1 st biasing member;

a 2 nd biasing member that biases the front wheel speed increasing clutch to the disengaged state;

a 2 nd hydraulic piston provided in the front wheel speed increasing clutch, the 2 nd hydraulic piston being operated by the hydraulic pressure supplied from the 2 nd operation oil passage and operating the front wheel speed increasing clutch to an engaged state against the 2 nd biasing member;

the 1 st force application component is arranged between the front wheel clutch and the bracket;

and an urging force transmission member slidably supported by the front wheel transmission shaft and transmitting the urging force of the 1 st urging member to the 1 st hydraulic piston.

6. The travel transmission of a tractor according to claim 5,

the 1 st urging member is a disc spring.

7. The travel transmission of a tractor according to claim 6,

a rear wheel transmission shaft provided in parallel with the front wheel transmission shaft and transmitting power to the rear wheel differential mechanism;

an emergency brake provided on the rear wheel transmission shaft;

an outer peripheral portion of the emergency brake enters between the front wheel clutch and the disc spring.

8. The running gear of a tractor according to any one of claims 1 to 7,

a transmission case for accommodating the transmission;

the front wheel speed increasing clutch is arranged at the lower part of the inner space of the transmission case;

a speed-increasing clutch cover disposed in the internal space and covering the front wheel speed-increasing clutch;

the speed increasing clutch cover has an opening formed upward.

9. The running gear of a tractor according to any one of claims 1 to 8,

a transmission case for accommodating the transmission;

the front wheel clutch is arranged at the lower part of the inner space of the transmission case;

a front wheel clutch cover disposed in the internal space and covering the front wheel clutch;

the front wheel clutch cover has an opening formed upward.

10. A running transmission device of a tractor is characterized in that,

the disclosed device is provided with:

a front wheel differential mechanism for transmitting power to the left and right front wheels;

a rear wheel differential mechanism for transmitting power to the left and right rear wheels;

a transmission to which power of a power source is input and which transmits the input power to the front wheel differential mechanism and the rear wheel differential mechanism; and

a transmission case for accommodating the transmission;

the transmission comprises:

a front wheel transmission shaft for transmitting power to the front wheel differential mechanism;

a front wheel clutch for transmitting power to the front wheel transmission shaft in a state where an average circumferential speed of the left and right front wheels is equal to an average circumferential speed of the left and right rear wheels; and

a front wheel speed increasing clutch for transmitting power to the front wheel transmission shaft in a state where an average circumferential speed of the left and right front wheels is faster than an average circumferential speed of the left and right rear wheels;

the front wheel speed increasing clutch is arranged at the lower part of the inner space of the transmission case;

a speed-increasing clutch cover disposed in the internal space and covering the front wheel speed-increasing clutch;

the speed increasing clutch cover has an opening formed upward.

11. The travel transmission of a tractor according to claim 10,

a rear wheel transmission shaft provided above the front wheel transmission shaft and transmitting power to the rear wheel differential mechanism;

the upper end of the speed increasing clutch cover is located at the same height as the axle center of the rear wheel transmission shaft or a position higher than the axle center.

12. The travel transmission of a tractor according to claim 10,

the speed increasing clutch cover comprises: a lower cover portion located below an upper end portion of the front wheel speed increasing clutch; and an upper cover portion extending upward from the lower cover portion.

13. The travel transmission of a tractor according to claim 12,

the lower cover part has: a 1 st lateral wall portion corresponding to one of both lateral side portions of a clutch drum of the front wheel speed increasing clutch that rotates in an ascending direction when forward power is transmitted and viewed in a direction along a rotating shaft core of the clutch drum; and a 2 nd horizontal wall portion corresponding to one of the two horizontal side portions that rotates in a descending direction when forward power is transmitted and viewed in the direction;

the upper cover portion extends upward only from the 1 st lateral wall portion of the 1 st lateral wall portion and the 2 nd lateral wall portion.

14. The running gear of a tractor according to any one of claims 10 to 13,

the front wheel clutch is arranged at the lower part of the inner space of the transmission case;

the vehicle front wheel clutch cover is provided in the internal space and covers the front wheel clutch.

15. The travel transmission of a tractor according to claim 14,

a rear wheel transmission shaft provided above the front wheel transmission shaft and transmitting power to the rear wheel differential mechanism;

the upper end of the front wheel clutch cover is located at the same height as the axle center of the rear wheel transmission shaft or at a position higher than the axle center.

Technical Field

The present invention relates to a travel transmission device for a tractor, the travel transmission device for a tractor comprising: a front wheel differential mechanism for transmitting power to the left and right front wheels; a rear wheel differential mechanism for transmitting power to the left and right rear wheels; and a transmission (transmission) to which power of a power source is input and which transmits the input power to the front wheel differential mechanism and the rear wheel differential mechanism.

Background

As shown in patent document 1, for example, the travel transmission device of the tractor has the following structure: a constant speed clutch and a speed increasing clutch are arranged on a transmission shaft for transmitting power to the front wheel differential mechanism; if the speed increasing clutch is disconnected and the constant speed clutch is connected, the power transmitted to the rear wheel differential device is power-transmitted to the propeller shaft so that the rear wheels and the front wheels rotate at substantially the same peripheral speed; if the constant speed clutch is disengaged and the speed increasing clutch is engaged, the power transmitted to the rear wheel differential device is increased in speed and transmitted to the propeller shaft; if both the speed increasing clutch and the constant speed clutch are disengaged, power is not transmitted to the front wheels, and the tractor is driven only by the rear wheels.

In the structure shown in patent document 1, the clutch body of the constant speed clutch and the clutch body of the speed increasing clutch are integrally provided on the propeller shaft.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2008-143411.

Disclosure of Invention

Problems to be solved by the invention

In the above-described travel transmission device for a tractor, a front wheel clutch that can be switched between an engaged state in which power is transmitted to the front wheel transmission shaft and a disengaged state in which power is transmitted to the front wheel transmission shaft is disengaged and that can switch between an engaged state in which the average circumferential speeds of the left and right front wheels and the average circumferential speeds of the left and right rear wheels are equal to each other in the engaged state and a disengaged state in which power is transmitted to the front wheel transmission shaft are disengaged are supported by the front wheel transmission shaft, and a front wheel speed increasing clutch that can be switched between an engaged state in which power is transmitted to the front wheel transmission shaft and a disengaged state in which power is transmitted to the front wheel transmission shaft and that can switch between the engaged state and the disengaged state in which power is transmitted to the front wheel transmission shaft in the engaged state and that transmits power to the front wheel transmission shaft in the engaged state in which the average circumferential speeds of the left and right front wheels are faster than the average circumferential speeds of the left and right rear wheels; thereby it can be presented: a two-drive state in which only the rear wheel of the front and rear wheels is driven; a four-wheel drive state in which the average circumferential speeds of the left and right front wheels are equal to the average circumferential speeds of the left and right rear wheels; and a four-wheel drive state in which the average circumferential speeds of the left and right front wheels are faster than the average circumferential speeds of the left and right rear wheels. In the travel transmission device of a tractor of this type, in order to provide a 1 st operation oil passage for switching the front wheel clutch and a 2 nd operation oil passage for switching the front wheel speed increasing clutch in the front wheel propeller shaft, in the case of adopting the conventional technique, the 1 st operation oil passage and the 2 nd operation oil passage are extended toward the front wheel clutch and the front wheel speed increasing clutch to be operated from a position on the opposite side to the side where the other clutch is located in the front wheel propeller shaft with respect to the one clutch of the front wheel clutch and the front wheel speed increasing clutch, so that the one operation oil passage of the 1 st operation oil passage and the 2 nd operation oil passage is arranged in the radial direction of the front wheel propeller shaft with the other operation oil passage at a portion on the opposite side to the clutch side, and the length of the operation oil passages is increased due to this arrangement.

In such a travel transmission device for a tractor, since the lubricating oil in the transmission case (transmission case) is stirred by the rotation of the front wheel speed increasing clutch and the rotation speed of the front wheel speed increasing clutch is high for increasing the speed of the front wheel, it is desirable to suppress the temperature rise of the lubricating oil due to the stirring of the lubricating oil by the front wheel speed increasing clutch.

The invention provides a travel transmission device of a tractor capable of ensuring a short length of an operation oil path in a device capable of presenting a two-drive state, a four-drive state with constant speed of front and rear wheels and a four-drive state with speed-up of the front wheels, and a travel transmission device of a tractor capable of inexpensively suppressing temperature rise of lubricating oil caused by rotation of a front wheel speed-up clutch.

Means for solving the problems

The travel transmission device of a tractor of the present invention includes: a front wheel differential mechanism for transmitting power to the left and right front wheels; a rear wheel differential mechanism for transmitting power to the left and right rear wheels; and a transmission to which power of a power source is input and which transmits the input power to the front wheel differential mechanism and the rear wheel differential mechanism; the transmission comprises: a front wheel transmission shaft for transmitting power to the front wheel differential mechanism; a front wheel clutch which can be switched between an engaged state in which power is transmitted to the front wheel propeller shaft and a disengaged state in which power transmission to the front wheel propeller shaft is disengaged, and which transmits power to the front wheel propeller shaft in a state in which an average circumferential speed of the left and right front wheels is equal to an average circumferential speed of the left and right rear wheels in the engaged state; and a front wheel speed increasing clutch which can be switched between an engaged state in which power is transmitted to the front wheel propeller shaft and a disengaged state in which power transmission to the front wheel propeller shaft is disengaged, and which can transmit power to the front wheel propeller shaft in a state in which the average circumferential speed of the left and right front wheels is faster than the average circumferential speed of the left and right rear wheels in the engaged state; the front wheel clutch and the front wheel speed-up clutch are supported by the front wheel transmission shaft in a state of being arranged in the axial direction of the front wheel transmission shaft; a bracket that rotatably supports the front wheel transmission shaft is provided between the front wheel clutch and the front wheel speed increasing clutch; a 1 st operation oil path is arranged across the front wheel transmission shaft and the bracket in a penetrating manner, and the 1 st operation oil path carries out switching operation on the front wheel clutch; and a 2 nd operation oil path is arranged across the front wheel transmission shaft and the bracket in a penetrating manner, and the 2 nd operation oil path carries out switching operation on the front wheel speed increasing clutch.

According to this configuration, the power transmission to the front wheel propeller shaft is disconnected and the power is not transmitted to the front wheel differential mechanism by switching the front wheel clutch to the disengaged state and switching the front wheel speed-up clutch to the disengaged state, so that only the rear wheels among the front wheels and the rear wheels are driven. Since the power is transmitted to the front wheel propeller shaft in a state where the average circumferential speeds of the left and right front wheels are equal to the average circumferential speeds of the left and right rear wheels by switching the front wheel clutch to the engaged state and switching the front wheel speed increasing clutch to the disengaged state, and the power of the front wheel propeller shaft is transmitted to the front wheel differential mechanism, the front wheels and the rear wheels are driven in a state where the average circumferential speeds of the left and right front wheels are equal to the average circumferential speeds of the left and right rear wheels. Since the power of the front wheel propeller shaft is transmitted to the front wheel differential mechanism in a state where the average circumferential speed of the left and right front wheels is faster than the average circumferential speed of the left and right rear wheels by switching the front wheel clutch to the disengaged state and switching the front wheel speed-increasing clutch to the engaged state, the front wheels and the rear wheels are driven in a state where the average circumferential speed of the left and right front wheels is faster than the average circumferential speed of the left and right rear wheels.

Since the portion of the 1 st operation oil path that is located on the front wheel propeller shaft extends from the portion of the front wheel propeller shaft that corresponds to the carrier to the portion of the front wheel propeller shaft that corresponds to the front wheel clutch, and the portion of the 2 nd operation oil path that is located on the front wheel propeller shaft extends from the portion of the front wheel propeller shaft that corresponds to the carrier to the portion of the front wheel propeller shaft that corresponds to the front wheel speed-up clutch, the 1 st operation oil path and the 2 nd operation oil path are not arranged in the radial direction of the front wheel propeller shaft.

Therefore, a two-drive state in which only the rear wheels are driven, a four-drive state in which the front and rear wheels are constant in speed, and a four-drive state in which the front wheels are accelerated can be exhibited, and in a structure in which the 1 st operation oil passage and the 2 nd operation oil passage are bored in the front wheel propeller shaft, it is sufficient to make the 1 st operation oil passage and the 2 nd operation oil passage short in length.

In the present invention, it is preferable that the bracket includes a support portion that is fitted to a rotating member of the front wheel speed increasing clutch so as to be relatively rotatable, and supports the rotating member; a bearing is interposed between the rotating member and the support portion.

According to this configuration, the front wheel speed increasing clutch can be smoothly rotated by reliably supporting the front wheel speed increasing clutch with a support structure having a simple structure in which the bracket is used as the support member of the rotating member.

In the present invention, it is preferable that the transmission case is provided with a transmission case for housing the transmission; the bracket is supported by a wall portion of the transmission case in a state of being formed separately from the transmission case; a 2 nd carrier that rotatably supports the front wheel transmission shaft at a position located on the opposite side of the front wheel clutch from the front wheel speed increasing clutch; the 2 nd bracket is supported by a wall portion of the transmission case other than the wall portion in a state of being formed separately from the transmission case.

According to this configuration, even if the wall portion of the transmission case does not include the support portion for the front wheel propeller shaft, the front wheel propeller shaft is supported by the 2 nd bracket on the side opposite to the side on which the front wheel clutch is positioned with respect to the front wheel speed increasing clutch, so that the front wheel propeller shaft and the front wheel speed increasing clutch can be reliably supported while the transmission case is formed into a simple shape.

In the present invention, it is preferable that a spacer is provided, the spacer being connected to a portion of the bracket that is offset from the wall portion and a portion of the 2 nd bracket that is offset from the other wall portion, and setting a distance between the bracket and the 2 nd bracket.

According to this configuration, since the distance between the portion of the carrier that is offset from the wall of the transmission case and the portion of the 2 nd carrier that is offset from the wall of the transmission case can be set by the spacer to a distance suitable for positioning the front wheel speed increasing clutch between the carrier and the 2 nd carrier, the front wheel propeller shaft and the front wheel speed increasing clutch can be reliably supported while the carrier and the 2 nd carrier are supported by the wall in a cantilevered state.

In the present invention, it is preferable that the vehicle seat further includes a 1 st biasing member that biases the front wheel clutch to the engaged state; a 1 st hydraulic piston provided in the front wheel clutch, and operated by the hydraulic pressure supplied from the 1 st operation oil passage to operate the front wheel clutch to the disengaged state against the 1 st biasing member; a 2 nd biasing member that biases the front wheel speed increasing clutch to the disengaged state; a 2 nd hydraulic piston provided in the front wheel speed increasing clutch, the 2 nd hydraulic piston being operated by the hydraulic pressure supplied from the 2 nd operation oil passage and operating the front wheel speed increasing clutch to an engaged state against the 2 nd biasing member; the 1 st force application component is arranged between the front wheel clutch and the bracket; and an urging force transmission member slidably supported by the front wheel transmission shaft and transmitting the urging force of the 1 st urging member to the 1 st hydraulic piston.

According to this configuration, even when the hydraulic pressure supply source is stopped and the hydraulic pressure supply to the 1 st hydraulic piston and the 2 nd hydraulic piston is stopped, for example, when the engine is stopped, the front wheel clutch is switched to the engaged state by the 1 st biasing member and the front wheel speed increase clutch is switched to the disengaged state by the 2 nd biasing member, so that the front wheels can be connected to the brake via the front wheel clutch. Since the 1 st biasing member is located at a position away from the front wheel clutch, the 1 st biasing member can be formed larger than the biasing member provided to the front wheel clutch, and the like, and can have a stronger biasing force, so that the front wheel clutch can be reliably maintained in the engaged state by the 1 st biasing member against the rotational operation force by the front wheel.

That is, even if the supply of the hydraulic pressure to the 1 st hydraulic piston and the 2 nd hydraulic piston is stopped in the inclined terrain, the brake can be reliably applied to the vehicle body.

In the present invention, it is preferable that the 1 st urging member is a disc spring.

According to this configuration, the space required for installing the 1 st biasing member is enough to be small, and a strong biasing force for biasing the front wheel clutch to the engaged state can be provided.

In the present invention, it is preferable that the vehicle further includes a rear wheel propeller shaft provided in parallel with the front wheel propeller shaft and transmitting power to the rear wheel differential mechanism; an emergency brake provided on the rear wheel transmission shaft; an outer peripheral portion of the emergency brake enters between the front wheel clutch and the disc spring.

According to this configuration, the space between the front wheel clutch and the disc spring is used as the installation space of the emergency brake, so that a compact configuration including the emergency brake can be obtained.

In the present invention, it is preferable that the transmission case is provided with a transmission case for housing the transmission; the front wheel speed increasing clutch is arranged at the lower part of the inner space of the transmission case; a speed-increasing clutch cover disposed in the internal space and covering the front wheel speed-increasing clutch; the speed increasing clutch cover has an opening formed upward.

According to this configuration, since the lubricating oil stored in the transmission case flows into the inside of the speed increasing clutch cover through the opening, the lubricating oil can be stored in the peripheral region of the front wheel speed increasing clutch in the internal space of the transmission case. Although the lubricating oil located in the peripheral region of the front wheel speed increasing clutch is stirred by the rotation of the front wheel speed increasing clutch, the stirring by the front wheel speed increasing clutch is less likely to reach the lubricating oil located in the region deviated from the peripheral region of the front wheel speed increasing clutch because the speed increasing clutch cover exerts a wave-preventing action on the stirred lubricating oil, and the temperature increase of the lubricating oil in the transmission case can be suppressed.

In the present invention, it is preferable that the transmission case is provided with a transmission case for housing the transmission; the front wheel clutch is arranged at the lower part of the inner space of the transmission case; a front wheel clutch cover disposed in the internal space and covering the front wheel clutch; the front wheel clutch cover has an opening formed upward.

According to this configuration, since the lubricating oil stored in the transmission case flows into the front clutch cover through the opening, the lubricating oil can be stored in the peripheral region of the front clutch in the internal space of the transmission case. The lubricating oil located in the peripheral region of the front wheel clutch is stirred by the rotation of the front wheel clutch, but since the front wheel clutch cover exerts a wave-preventing action on the stirred lubricating oil, the stirring by the front wheel clutch is less likely to reach the lubricating oil located in a region deviated from the peripheral region of the front wheel clutch, and the temperature increase of the lubricating oil in the transmission case can be suppressed.

Another travel transmission device for a tractor according to the present invention includes: a front wheel differential mechanism for transmitting power to the left and right front wheels; a rear wheel differential mechanism for transmitting power to the left and right rear wheels; a transmission to which power of a power source is input and which transmits the input power to the front wheel differential mechanism and the rear wheel differential mechanism; and a transmission case for accommodating the transmission; the transmission comprises: a front wheel transmission shaft for transmitting power to the front wheel differential mechanism; a front wheel clutch for transmitting power to the front wheel transmission shaft in a state where an average circumferential speed of the left and right front wheels is equal to an average circumferential speed of the left and right rear wheels; and a front wheel speed increasing clutch for transmitting power to the front wheel transmission shaft in a state where the average circumferential speed of the left and right front wheels is faster than the average circumferential speed of the left and right rear wheels; the front wheel speed increasing clutch is arranged at the lower part of the inner space of the transmission case; a speed-increasing clutch cover disposed in the internal space and covering the front wheel speed-increasing clutch; the speed increasing clutch cover has an opening formed upward.

According to this configuration, since the lubricating oil stored in the transmission case flows into the inside of the speed increasing clutch cover through the opening, the lubricating oil can be stored in the peripheral region of the front wheel speed increasing clutch in the internal space of the transmission case. Although the lubricating oil located in the peripheral region of the front wheel speed increasing clutch is stirred by the rotation of the front wheel speed increasing clutch, the stirring by the front wheel speed increasing clutch is less likely to reach the lubricating oil located in the region deviated from the peripheral region of the front wheel speed increasing clutch because the speed increasing clutch cover exerts a wave-preventing action on the stirred lubricating oil, and the temperature increase of the lubricating oil in the transmission case can be suppressed. Since a simple structure is sufficient to provide only the speed increasing clutch cover, temperature increase can be suppressed at low cost.

In the present invention, it is preferable that the vehicle further comprises a rear wheel propeller shaft provided above the front wheel propeller shaft and transmitting power to the rear wheel differential mechanism; the upper end of the speed increasing clutch cover is located at the same height as the axle center of the rear wheel transmission shaft or a position higher than the axle center.

In such a traveling transmission device, the lubricating oil is generally stored in the transmission case in a state where the oil surface is located at a position where the shaft core of the rear wheel propeller shaft is located or above the shaft core, but according to this configuration, since the upper end of the speed increasing clutch cover is located near the oil surface, the speed increasing clutch cover appropriately exerts a wave-preventing action on the lubricating oil stirred by the rotation of the front wheel speed increasing clutch, and the temperature increase of the lubricating oil due to the rotation of the front wheel speed increasing clutch can be effectively suppressed.

In the present invention, it is preferable that the speed increasing clutch cover includes: a lower cover portion located below an upper end portion of the front wheel speed increasing clutch; and an upper cover portion extending upward from the lower cover portion.

Since the upper cover portion exerts a wave-preventing action on the lubricating oil that rises and flows due to the agitation performed by the front wheel speed increasing clutch, it is possible to effectively suppress the temperature rise of the lubricating oil due to the rotation of the front wheel speed increasing clutch.

In the present invention, it is preferable that the lower cover portion has: a 1 st lateral wall portion corresponding to one of both lateral side portions of a clutch drum of the front wheel speed increasing clutch that rotates in an ascending direction when forward power is transmitted and viewed in a direction along a rotating shaft core of the clutch drum; and a 2 nd horizontal wall portion corresponding to one of the two horizontal side portions that rotates in a descending direction when forward power is transmitted and viewed in the direction; the upper cover portion extends upward only from the 1 st lateral wall portion of the 1 st lateral wall portion and the 2 nd lateral wall portion.

Because of the lubricating oil which is stirred and flows upwards by the lateral side part rotating in the ascending direction and the lubricating oil which is stirred and flows downwards by the lateral side part rotating in the descending direction, the upper cover part plays a wave-preventing function for lubricating oil which is easy to affect the rising flow of the lubricating oil in the area deviated from the peripheral area of the front wheel speed increasing clutch, and moreover, since the upper cover portion exerts a wave-preventing action on the lubricating oil that flows upward and is generated during forward travel that is performed more frequently than during reverse travel, therefore, while the speed increasing clutch cover with simple structure is formed by extending only the upper cover part from the 1 st cross wall part, the agitation by the front wheel speed increasing clutch is less likely to be applied to the lubricating oil in the region deviated from the peripheral region of the front wheel speed increasing clutch, and the temperature rise of the lubricating oil due to the rotation of the front wheel speed increasing clutch can be effectively suppressed.

In the present invention, it is preferable that the front wheel clutch is disposed at a lower portion of an internal space of the transmission case; the vehicle front wheel clutch cover is provided in the internal space and covers the front wheel clutch.

According to this configuration, although the lubricating oil located in the peripheral region of the front wheel clutch is stirred by the rotation of the front wheel clutch, the stirring by the front wheel clutch is less likely to reach the lubricating oil located in the region deviated from the peripheral region of the front wheel clutch because the front wheel clutch cover exerts a wave-shielding effect on the stirred lubricating oil, and the temperature increase of the lubricating oil by the rotation of the front wheel clutch can be suppressed.

In the present invention, it is preferable that the vehicle further comprises a rear wheel propeller shaft provided above the front wheel propeller shaft and transmitting power to the rear wheel differential mechanism; the upper end of the front wheel clutch cover is located at the same height as the axle center of the rear wheel transmission shaft or at a position higher than the axle center.

In such a traveling transmission device, the lubricating oil is generally stored in the transmission case in a state where the oil surface is located at a position where the shaft core of the rear wheel propeller shaft is located or at a position above the shaft core, but according to this configuration, since the upper end of the front wheel clutch cover is located in the vicinity of the oil surface, the front wheel clutch cover appropriately exerts a wave-shielding effect on the lubricating oil stirred by the rotation of the front wheel clutch, and the temperature increase of the lubricating oil due to the rotation of the front wheel clutch can be effectively suppressed.

Drawings

Fig. 1 is a left side view showing the entirety of a tractor.

Fig. 2 is a diagram showing a travel transmission.

Fig. 3 is a longitudinal sectional side view of the front wheel drive.

Fig. 4 is a perspective view showing a holder (holder), a 2 nd holder and a spacer (spacer).

Fig. 5 is a left side view showing the speed increasing clutch cover and the front wheel clutch cover.

Fig. 6 is a vertical cross-sectional side view of the speed increasing clutch cover and the front wheel clutch cover.

Fig. 7 is a longitudinal rear sectional view of the speed increasing clutch cover.

Fig. 8 is a vertical rear view showing the speed increasing clutch cover and the spacer.

Fig. 9 is a perspective view showing a speed increasing clutch cover.

Fig. 10 is a perspective view showing a speed increasing clutch cover.

Fig. 11 is a longitudinal rear view of the front wheel clutch cover.

Fig. 12 is a perspective view showing a front wheel clutch cover.

Detailed Description

Hereinafter, an embodiment of the present invention will be described based on the drawings.

In the following description, regarding the tractor body, the direction of arrow F shown in fig. 1 is referred to as "front vehicle body", the direction of arrow B is referred to as "rear vehicle body", the direction of arrow U shown in fig. 1 is referred to as "upper vehicle body", the direction of arrow D is referred to as "lower vehicle body", the direction on the front side of the drawing sheet is referred to as "left vehicle body", and the direction on the back side of the drawing sheet is referred to as "right vehicle body".

[ integral structure of tractor ]

As shown in fig. 1, the tractor includes a vehicle body 3, and the vehicle body 3 is equipped with a pair of left and right front wheels 1 and a pair of left and right rear wheels 2 so as to be steerable and drivable. A prime mover 5 having an engine 4 as a power source is formed at the front portion of the vehicle body 3. A riding-type steering unit 8 is formed in the rear portion of the vehicle body 3, and the steering unit 8 includes a steering seat 6 and a steering wheel 7 for steering the front wheels 1. The driving unit 8 includes a cabin 9 covering the boarding space. A link mechanism 10 that connects various working devices such as a rotary tilling device (not shown) to be vertically operable and a power take-off shaft 11 that transmits power of the engine 4 to the connected working devices are provided at a rear portion of the vehicle body 3.

As shown in fig. 1, a vehicle body frame 3A of the vehicle body 3 includes an engine 4, a clutch housing 12 having a front portion coupled to a rear portion of the engine 4, a transmission case 13 having a front portion coupled to a rear portion of the clutch housing 12, and a front wheel support frame 14 coupled to a lower portion of the engine 4. The left and right front wheels 1 are rotatably supported by lateral ends of a front wheel drive case 15, and the front wheel drive case 15 is supported by a front wheel support frame 14 in a state of extending in the lateral width direction of the vehicle body. The left and right rear wheels 2 are rotatably supported by a rear wheel support case 16, and the rear wheel support case 16 extends from the rear portion of the transmission case 13 toward the vehicle body lateral outer side.

[ Structure of travel transmission ]

The travel transmission 20 that transmits the power of the engine 4 to the front wheels 1 and the rear wheels 2 is configured as shown in fig. 2.

As shown in fig. 2, the travel transmission device 20 includes: a front wheel differential mechanism 21 that transmits power to the left and right front wheels 1 (see fig. 1); a rear wheel differential mechanism 22 for transmitting power to the left and right rear wheels 2 (see fig. 1); and a transmission 23 to which power of the engine 4 as a power source is input, and which shifts the input power and transmits the shifted power to the front wheel differential mechanism 21 and the rear wheel differential mechanism 22. The front wheel differential mechanism 21 is provided inside the front wheel drive case 15 (see fig. 1). The rear wheel differential mechanism 22 is housed in the rear portion of the transmission case 13.

As shown in fig. 2, the transmission 23 is housed in the transmission case 13. The transmission case 13 has: a front case section 13A, a front part of which is detachably connected to a rear part of the clutch housing 12 that houses the main clutch 24, and houses the forward/reverse switching device 25 and the like; and a rear case section 13B, the front part of which is detachably connected to the rear part of the front case section 13A, and which houses the rear wheel differential mechanism 22 and the like.

As shown in fig. 2, the transmission 23 includes: a forward/reverse switching device 25 that converts power input to the output shaft 4a of the engine 4 into forward power and reverse power by inputting the power via the main clutch 24; a transmission 26 for shifting the forward power and the reverse power output from the forward/reverse switching device 25; a rear wheel propeller shaft 27 for transmitting the forward power and the reverse power output from the transmission 26 to the rear wheel differential mechanism 22; a front wheel transmission 28 to which the forward power and the reverse power output from the transmission 26 are input; and a front wheel propeller shaft 29 for transmitting the forward power and the reverse power output from the front wheel transmission device 28 to the front wheel differential mechanism 21. Fig. 2 shows a working clutch 30. The working clutch 30 is switched to the engaged state to transmit the power of the relay shaft 31 linked to the input shaft 25a of the forward/reverse switching device 25 to the power take-off shaft 11, and is switched to the disengaged state to disconnect the power transmission to the power take-off shaft 11.

As shown in fig. 2, the forward/reverse switching device 25 includes an input shaft 25a linked to the output shaft 4a of the engine 4 via a main clutch 24, and a forward clutch 25b and a reverse clutch 25c provided on the input shaft 25 a. The forward clutch 25b and the reverse clutch 25c are formed of wet type hydraulically operated multiple disc clutches.

In the forward/reverse switching device 25, the forward clutch 25b is switched to the engaged state and the reverse clutch 25c is switched to the disengaged state, whereby the power of the engine 4 input from the input shaft 25a is converted into forward power and output from the output gear 25 d. In the forward/reverse switching device 25, the forward clutch 25b is switched to the disengaged state and the reverse clutch 25c is switched to the engaged state, whereby the power of the engine 4 input from the input shaft 25a is converted into reverse power and output from the output gear 25 d.

As shown in fig. 2, the transmission 26 includes: an input shaft 33 to which power of the output gear 25d of the forward/reverse switching device 25 is input; an intermediate shaft 34 externally fitted to the relay shaft 31 so as to be relatively rotatable; an output shaft 35 provided below the intermediate shaft 34; a main transmission unit 26A provided across the input shaft 33 and the intermediate shaft 34; and a sub-transmission unit 26B provided across the intermediate shaft 34 and the output shaft 35.

In the transmission 26, the power of the input shaft 33 is mainly shifted by the main shift portion 26A into 6-step shift power of 1 st to 6 th, the shift power after the main shift is sub-shifted by the sub-shift portion 6B into 2-step shift power of high and low speeds, and the sub-shifted shift power is output from the output shaft 35.

As shown in fig. 2 and 3, the rear wheel propeller shaft 27 is disposed above the front wheel propeller shaft 29 and is aligned in parallel with the front wheel propeller shaft 29. The rear wheel propeller shaft 27 is provided rearward of the output shaft 35 of the transmission 26, and is arranged in a straight line with respect to the output shaft 35. An emergency brake 36 is provided across a rear end portion of the output shaft 35 of the transmission 26 and a front end portion of the rear wheel propeller shaft 27. A front wheel clutch 40 is provided on the front wheel propeller shaft 29, and a plurality of disc springs 39 are provided on the front wheel propeller shaft 29 behind the front wheel clutch 40. The emergency brake 36 is provided in a state where an outer peripheral portion of the emergency brake 36 enters between the front wheel clutch 40 and the disc spring 39. As shown in fig. 3, the output shaft 35 and the rear propeller shaft 27 are coupled to each other so as not to rotate relative to each other by a rotating member 36a of the emergency brake 36. The rotating member 36a supports the friction plate, and is linked to the output shaft 35 and the rear wheel propeller shaft 27 by spline engagement. An input gear 22a of the rear wheel differential mechanism 22 is provided at the rear end of the rear wheel propeller shaft 27 so as not to be relatively rotatable. The forward power and the reverse power of the output shaft 35 of the transmission 26 are transmitted to the rear propeller shaft 27 by the rotating member 36 a. The rear propeller shaft 27 transmits the transmitted forward power and reverse power to the rear differential mechanism 22 at the transmitted rotational speed. The emergency brake 36 is a multi-plate friction brake. The emergency brake 36 is used when the engine is stopped or the like. When the emergency brake 36 is switched to the engaged state, a braking force is applied to the left and right rear wheels 2 via the rear propeller shaft 27 and the rear differential mechanism 22, and a braking force is applied to the left and right front wheels 1 via the output shaft 35, the front wheel transmission 28, the front propeller shaft 29, the front wheel output shaft 37, the rotary shaft 38, and the front differential mechanism 21.

As shown in fig. 2 and 3, the output portion of the front wheel transmission 28 is provided on a front wheel transmission shaft 29. The front end of the front wheel propeller shaft 29 is connected to the rear end of the front wheel output shaft 37 so as not to be relatively rotatable, and the front end of the front wheel output shaft 37 and the input gear 21a of the front wheel differential mechanism 21 are linked by the rotary shaft 38. The forward power and the reverse power output from the front wheel transmission 28 are input to a front wheel transmission shaft 29. The front propeller shaft 29 transmits the input forward power and reverse power to the front wheel differential mechanism 21 via the front wheel output shaft 37 and the rotary shaft 38.

[ Structure of front wheel Transmission ]

As shown in fig. 3, the front wheel transmission 28 includes a front wheel clutch 40 and a front wheel speed increasing clutch 60 that are arranged in the axial direction of the front wheel propeller shaft 29 and supported by the front wheel propeller shaft 29. In the present embodiment, the front wheel clutch 40 is disposed in front of the front wheel acceleration clutch 60, but the front wheel clutch 40 may be disposed behind the front wheel acceleration clutch 60.

As shown in fig. 3, the front wheel clutch 40 includes a clutch hub (clutch hub) 42 supported by the front wheel propeller shaft 29 via a bearing 41 so as to be relatively rotatable, and a clutch drum (clutch drum) 43 supported by the front wheel propeller shaft 29 so as not to be relatively rotatable. A sleeve (boss) portion 43a of the clutch drum 43 is fitted to the front wheel drive shaft 29, the sleeve portion 43a and the front wheel drive shaft 29 are coupled by a key 44 so as not to be relatively rotatable, and the clutch drum 43 is supported by the front wheel drive shaft 29 so as not to be relatively rotatable.

The clutch hub 42 includes a constant speed input gear 45 provided at a front portion of the clutch hub 42 so as not to be relatively rotatable. The constant speed input gear 45 meshes with a constant speed transmission gear 46 provided in the output shaft 35 of the transmission device 26 so as not to be relatively rotatable. The gear ratio between the constant speed input gear 45 and the constant speed transmission gear 46 is set to a gear ratio at which the rotational speed of the output shaft 35 is equal to the rotational speed of the front wheel propeller shaft 29.

Inside the clutch drum 43, a pair of inner spaces 43c partitioned by an outer ring (rim) portion 43b and arranged in the front-rear direction are provided. In the front inner space 43c of the pair of inner spaces 43c, multiple-plate clutch plates 47 are provided across the clutch hub 42 and the clutch drum 43. A pressing member 48 for pressing the clutch plate 47 is slidably provided in the front inner space 43 c. The 1 st hydraulic piston 49 is slidably provided in the rear internal space 43c of the pair of internal spaces 43 c. The 1 st hydraulic piston 49 and the pressing member 48 are linked by a linking member 50, and the linking member 50 extends forward from a plurality of locations in the circumferential direction of the 1 st hydraulic piston 49. The plurality of coupling members 50 slidably insert the outer ring portion 43b therethrough. The front wheel clutch 40 is a so-called wet and hydraulically operated multiple disc clutch.

Between the center bracket 70B that supports the front wheel propeller shaft 29 behind the front wheel clutch 40 and the front wheel clutch 40, a plurality of disc springs 39 as the 1 st urging members are arranged in the axial direction of the front wheel propeller shaft 29 and externally fitted to the front wheel propeller shaft 29. The disc spring 39 is configured to bias the front wheel clutch 40 to the engaged state.

Specifically, the outer fitting of the disc spring 39 to the front wheel transmission shaft 29 is performed via a rearward extension 43d of the sleeve portion 43a of the clutch drum 43 and a support tube 51 interposed between the extension 43d and the disc spring 39. The support cylinder 51 is supported from behind by a stopper 52 formed on the extension portion 43 d. The plurality of disc springs 39 are received and supported from the rear by stoppers 53 formed at the rear of the support tube 51.

A cylindrical force transmission member 54 is fitted over the rear portion 49a of the 1 st hydraulic piston 49 and the front portion of the support cylinder 51. The urging force transmitting member 54 is fitted to the support tube 51 so as to be slidable. The front end portion of the urging force transmission member 54 engages with a step portion formed in the rear portion 49a of the 1 st hydraulic piston 49 in a state of coming into contact from behind. The rear end portion of the biasing force transmitting member 54 engages with the foremost disc spring 39 of the plurality of disc springs 39 in a state of coming into contact from the front. The plate spring 39 is operated to press the biasing force transmitting member 54 against the 1 st hydraulic piston 49 by the elastic restoring force, and the biasing force transmitting member 54 is operated to press the 1 st hydraulic piston 49 against the outer ring portion 43b, whereby the elastic restoring force of the plate spring 39 is transmitted to the 1 st hydraulic piston 49 by the biasing force transmitting member 54, and the 1 st hydraulic piston 49 is biased toward the engaged position by the plate spring 39.

The front wheel clutch 40 is switched between the on state and the off state by the 1 st hydraulic piston 49 and the coned disc spring 39.

That is, if the hydraulic pressure is supplied between the 1 st hydraulic piston 49 and the outer ring portion 43b, the 1 st hydraulic piston 49 is moved to the unseated position against the biasing force of the coned disc spring 39 by the supplied hydraulic pressure, the pressing member 48 is slid in the direction of the outer ring portion 43b by the 1 st hydraulic piston 49, the pressure contact of the clutch plate 47 by the pressing member 48 is released, the interlocking connection of the clutch drum 43 and the clutch hub 42 by the clutch plate 47 is released, and the front wheel clutch 40 is brought into the disengaged state.

If the front wheel clutch 40 is switched to the off state, the power transmission from the constant velocity transmission gear 46 to the front wheel propeller shaft 29 is disconnected by the front wheel clutch 40. That is, the front wheel clutch 40 is switched to the disengaged state, thereby disconnecting the transmission of the forward power and the reverse power output from the transmission 26 to the front wheel propeller shaft 29 and disconnecting the transmission of the power to the front wheel differential mechanism 21.

When the hydraulic pressure is discharged from between the 1 st hydraulic piston 49 and the outer ring portion 43b, the 1 st hydraulic piston 49 is moved to the engaged position by the biasing force of the coned disc spring 39, the pressing member 48 is slid by the 1 st hydraulic piston 49 in the direction of the clutch plate 47, the clutch plate 47 is pressed by the pressing member 48, the clutch drum 43 and the clutch hub 42 are interlocked and coupled by the clutch plate 47, and the front wheel clutch 40 is brought into the engaged state.

If the front wheel clutch 40 is switched to the engaged state, the power transmitted from the output shaft 35 of the transmission 26 to the constant velocity transmission gear 46 is transmitted to the front wheel propeller shaft 29 by the front wheel clutch 40, and is transmitted to the front wheel differential mechanism 21 from the front wheel propeller shaft 29. In this case, the rotational speed of the output shaft 35 is equal to the rotational speed of the front wheel propeller shaft 29 by the gear ratio between the constant velocity transmission gear 46 and the constant velocity input gear 45. Since the power of the output shaft 35 is transmitted to the rear propeller shaft 27 as the rotational speed of the output shaft 35, the front wheel clutch 40 is switched to the engaged state, and the power is transmitted to the front propeller shaft 29 in a state where the average circumferential speed of the left and right front wheels 1 is equal to the average circumferential speed of the left and right rear wheels 2.

As shown in fig. 3, the front wheel speed increasing clutch 60 includes a clutch hub 62 relatively rotatably supported by the front wheel drive shaft 29 via a bearing 61, and a clutch drum 63 relatively non-rotatably supported by the front wheel drive shaft 29. The clutch hub 62 supports the front wheel propeller shaft 29 by fitting a sleeve portion 62a of the clutch hub 62 to a rearward extension portion 63b of the sleeve portion 63a of the clutch drum 63, and interposing a bearing 61 between the extension portion 63b and the sleeve portion 62 a.

The clutch hub 62 includes a speed increasing input gear 64 provided at a rear portion of the clutch hub 62 so as not to be relatively rotatable. The speed increasing input gear 64 meshes with a speed increasing transmission gear 65 provided in the rear wheel drive shaft 27 so as not to be relatively rotatable. The gear ratio between the speed increasing input gear 64 and the speed increasing transmission gear 65 is set to a gear ratio such that the rotational speed of the front wheel propeller shaft 29 is faster than the rotational speed of the rear wheel propeller shaft 27.

In the inner space 63c of the clutch drum 63, multiple-plate clutch plates 66 are provided across the clutch hub 62 and the clutch drum 63. The 2 nd hydraulic piston 67 is slidably provided in the internal space 63 c. A coil spring 68 is provided as the 2 nd urging member in the internal space 63 c. The coil spring 68 is interposed between an end of the 2 nd hydraulic piston 67 and a stopper 69 formed in the sleeve portion 63 a. The coil spring 68 biases the 2 nd hydraulic piston 67 to the disengaged position, and biases the front wheel speed increasing clutch 60 to the disengaged state. The front wheel speed increasing clutch 60 is a so-called wet type and hydraulically operated multiple disc clutch.

The front wheel speed increasing clutch 60 is switched between an engaged state and an engaged state by the 2 nd hydraulic piston 67 and the coil spring 68.

That is, if the hydraulic pressure is supplied between the 2 nd hydraulic piston 67 and the outer ring portion 63d of the clutch drum 63, the 2 nd hydraulic piston 67 is operated to the engaged position against the coil spring 68 by the supplied hydraulic pressure, the clutch plate 66 is pressed against by the 2 nd hydraulic piston 67, the clutch drum 63 and the clutch hub 62 are linked and coupled by the clutch plate 66, and the front wheel speed increasing clutch 60 is brought into the engaged state.

When the front wheel speed increasing clutch 60 is switched to the engaged state, the power transmitted from the output shaft 35 of the transmission 26 to the speed increasing transmission gear 65 via the rear wheel propeller shaft 27 is transmitted to the front wheel propeller shaft 29 by the front wheel speed increasing clutch 60, and is transmitted to the front wheel differential mechanism 21 from the front wheel propeller shaft 29. In this case, the rotation speed of the front wheel propeller shaft 29 is faster than the rotation speed of the output shaft 35 by the gear ratio between the speed increasing transmission gear 65 and the speed increasing input gear 64. Since the power of the output shaft 35 is transmitted to the rear propeller shaft 27 at the rotational speed of the output shaft 35, the front wheel speed increasing clutch 60 is switched to the engaged state, and the power is transmitted to the front propeller shaft 29 at a higher average circumferential speed of the left and right front wheels 1 than the average circumferential speed of the left and right rear wheels 2.

When the hydraulic pressure is discharged from between the 2 nd hydraulic piston 67 and the outer ring portion 63d, the 2 nd hydraulic piston 67 is operated to the separated position by the biasing force of the coil spring 68, the pressure contact of the clutch plate 66 by the 2 nd hydraulic piston 67 is released, the interlocking connection of the clutch drum 63 and the clutch hub 62 by the clutch plate 66 is released, and the front wheel speed increasing clutch 60 is in the separated state.

If the front wheel speed increasing clutch 60 is switched to the off state, the power transmission from the speed increasing gear 65 to the front wheel propeller shaft 29 is disconnected by the front wheel speed increasing clutch 60. The front wheel speed increasing clutch 60 is switched to the off state, thereby disconnecting the transmission of the forward power and the reverse power output from the transmission 26 to the front wheel propeller shaft 29 and disconnecting the power transmission to the front wheel differential mechanism 21.

If the front wheel clutch 40 is switched to the off state and the front wheel speed increasing clutch 60 is switched to the off state, the power transmission from the constant speed transmission gear 46 to the front wheel propeller shaft 29 is disconnected by the front wheel clutch 40, the power transmission from the speed increasing transmission gear 65 to the front wheel propeller shaft 29 is disconnected by the front wheel speed increasing clutch 60, and the power transmission to the front wheel differential mechanism 21 is disconnected. The power of the output shaft 35 of the transmission 26 is transmitted to the rear wheel differential mechanism 22 by the rear propeller shaft 27 regardless of the engagement/disengagement of the front wheel clutch 40 and the front wheel speed increasing clutch 60. Thereby, the front wheels 1 are stopped to be in an idling state, and a two-drive state in which the rear wheels 2 are driven is assumed.

When the front wheel clutch 40 is switched to the engaged state and the front wheel speed increasing clutch 60 is switched to the disengaged state, the power of the output shaft 35 of the transmission device 26 is transmitted to the front wheel propeller shaft 29 at the constant speed transmission gear 46 and the front wheel clutch 40 at the same rotational speed, is transmitted to the front wheel differential mechanism 21 from the front wheel propeller shaft 29, and the power transmission from the speed increasing transmission gear 65 to the front wheel propeller shaft 29 is disconnected by the front wheel speed increasing clutch 60. The power of the output shaft 35 of the transmission 26 is transmitted to the rear wheel differential mechanism 22 by the rear wheel propeller shaft 27 at the same rotational speed. This results in a four-wheel drive state in which the front wheels 1 and the rear wheels 2 are driven, and the front and rear wheels have a constant speed, in which the average circumferential speeds of the left and right front wheels 1 and the average circumferential speeds of the left and right rear wheels 2 are equal to each other.

If the front wheel clutch 40 is switched to the off state and the front wheel speed increasing clutch 60 is switched to the on state, the power transmission from the constant speed transmission gear 46 to the front wheel propeller shaft 29 is disconnected by the front wheel clutch 40, and the power transmitted from the output shaft 35 of the transmission device 26 to the rear wheel propeller shaft 27 is increased in speed by the speed increasing transmission gear 65 and the front wheel speed increasing clutch 60, transmitted to the front wheel propeller shaft 29, and transmitted from the front wheel propeller shaft 29 to the front wheel differential mechanism 21. The power of the output shaft 35 of the transmission 26 is transmitted to the rear wheel differential mechanism 22 by the rear wheel propeller shaft 27 at the same rotational speed. This causes a four-wheel drive state in which the front wheels 1 and the rear wheels 2 are driven, and the average circumferential speed of the left and right front wheels 1 is faster than the average circumferential speed of the left and right rear wheels 2.

When the hydraulic pump (not shown) is stopped when the engine 4 is stopped and the hydraulic pump (not shown) is stopped, for example, if the hydraulic pressure supply to the 1 st hydraulic piston 49 and the 2 nd hydraulic piston 67 is stopped, even if the front wheel speed increasing clutch 60 is switched to the off state by the coil spring 68, the front wheel clutch 40 is switched to the on state by the disc spring 39 and the constant speed transmission gear 46 and the front wheel propeller shaft 29 are coupled to each other by the front wheel clutch 40, and the front wheels 1 are not in the idling state, and the braking force of the emergency brake 36 can be applied to the front wheels 1 via the front wheel clutch 40, the front wheel propeller shaft 29, and the like. Further, the front wheel clutch 40 can be reliably held in the engaged state by the strong urging force of the disc spring 39, so that the front wheel clutch 40 does not slip due to the operation force acting on the front wheel clutch 40 from the front wheel 1. Even in a sloping terrain, braking can be reliably applied to the vehicle body.

[ bearing for front wheel drive shaft ]

As shown in fig. 3, the front wheel propeller shaft 29 is supported by a bracket 70 that supports 3 positions of the front wheel propeller shaft 29 in the axial direction. Hereinafter, the foremost bracket 70 among the 3-part brackets 70 is referred to as a front bracket 70A. The rearmost bracket 70 (corresponding to the "bracket 2" constituting the claims) among the 3-position brackets 70 is referred to as a rear bracket 70C. The stent 70 between the front stent 70A and the rear stent 70C (corresponding to the "stent 3" constituting the claims) among the 3-site stents 70 is referred to as a middle stent 70B.

The front bracket 70A is formed by a wall portion of the transmission case 13 disposed in the internal space S of the transmission case 13. The front bracket 70A has a sleeve portion 71 through which the front wheel propeller shaft 29 is inserted. In the front wheel propeller shaft 29, a portion 29a located in front of the front wheel clutch 40 is rotatably supported by a sleeve portion 71 of a front carrier 70A via a bearing 72.

As shown in fig. 4, the intermediate bracket 70B is formed separately from the transmission case 13. The middle bracket 70B has: a bracket 75 having a sleeve portion 73 through which the front wheel drive shaft 29 is inserted and a support portion 74 projecting rearward from the sleeve portion 73; and a connecting arm portion 76 extending upward from the holder portion 75. As shown in fig. 3, the support portion 74 is configured to be fitted in an annular portion 63e formed in a front portion of the clutch drum 63 as a rotating member of the front wheel speed increasing clutch 60. A bearing 77 is interposed between the support portion 74 and the annular portion 63 e.

As shown in fig. 5 and 6, only the connecting arm portion 76 of the bracket portion 75 and the connecting arm portion 76 abuts against the wall portion 79 provided in the internal space S of the transmission case 13, and is detachably connected by the connecting bolt 76 a. The middle bracket 70B is supported by the wall portion 79 in a state where the bracket portion 75 is located at a position away from the wall portion 79. In the front wheel propeller shaft 29, a portion 29B between the front wheel clutch 40 and the front wheel speed increasing clutch 60 is rotatably supported by the sleeve portion 73 of the center stay 70B via a bearing 80. The clutch drum 63 of the front wheel speed increasing clutch 60 is rotatably supported by the support portion 74 of the center bracket 70B via a bearing 77.

As shown in fig. 4, the rear bracket 70C is formed separately from the transmission case 13. The rear bracket 70C includes a sleeve portion 81 and a pair of connecting arm portions 82 extending upward from the sleeve portion 81. As shown in fig. 3, the sleeve portion 81 is configured to be externally fitted to the extension portion 63b of the sleeve portion 63a of the clutch drum 63 via a bearing 83.

As shown in fig. 3, the other wall portion 84 than the wall portion 79 supporting the middle bracket 70B is disposed behind the wall portion 79 and is provided in the internal space S of the transmission case 13. As shown in fig. 5 and 6, only the connecting arm 82 of the connecting arm 82 and the sleeve portion 81 abuts against the wall portion 84, and is detachably connected by the connecting bolt 82 a. The rear bracket 70C is supported by the wall portion 84 in a state where the sleeve portion 81 is located at a position away from the wall portion 84. As shown in fig. 3, the extension portion 63b of the sleeve portion 63a of the clutch drum 63 is rotatably supported by the sleeve portion 81 via a bearing 83. That is, the front wheel propeller shaft 29 is rotatably supported by the sleeve portion 81 of the rear carrier 70C via the sleeve portion 63a and the bearing 83 at a portion located on the opposite side of the front wheel speed increasing clutch 60 from the side where the front wheel clutch 40 is located.

As shown in fig. 4 and 6, spacer coupling portions 78 are formed at 2 locations of the bracket portion 75, which is a portion of the middle bracket 70B that is offset from the wall portion 79. Spacer coupling portions 85 are formed at 2 locations of the sleeve portion 81, which is a portion of the rear bracket 70C that is offset from the wall portion 84. As shown in fig. 4, 5, and 6, the spacer 86 is coupled to the spacer coupling portion 78 of the middle bracket 70B and the spacer coupling portion 85 of the rear bracket 70C. The portion of the middle bracket 70B that is offset from the wall portion 79 and the portion of the rear bracket 70C that is offset from the wall portion 84 are coupled by 2 spacers 86. The interval between the portion of the center bracket 70B that is offset from the wall portion 79 and the portion of the rear bracket 70C that is offset from the wall portion 84 is set to an interval suitable for the distance that the front wheel speed increasing clutch 60 is positioned between the center bracket 70B and the rear bracket 70C by the spacer 86. The middle bracket 70B and the rear bracket 70C are reinforced with the spacer 86 as a reinforcing member.

[ operating device for front wheel clutch and front wheel speed-up clutch ]

As shown in fig. 3, a 1 st supply/discharge port 90 that supplies and discharges the hydraulic pressure between the outer ring portion 43b and the 1 st hydraulic piston 49 is formed in the sleeve portion 43a of the clutch drum 43 of the front wheel clutch 40. The 1 st supply/discharge port 90 and an operation valve (not shown) provided outside the transmission case 13 are connected via a 1 st operation oil passage 91 provided across the front wheel drive shaft 29 and the center bracket 70B. The 1 st operation oil path 91 has: a bracket oil path portion 91a inserted into the middle bracket 70B; and a shaft oil passage portion 91b that is bored from a portion corresponding to the carrier oil passage portion 91a to a portion corresponding to the 1 st supply and discharge port 90 in the front wheel drive shaft 29. In the front wheel propeller shaft 29, the shaft hole 92 formed by the end portion 91t on the center bracket side of the shaft oil passage portion 91b and the end portion 29c of the front wheel propeller shaft 29 is formed not for forming the 1 st operation oil passage 91 but for piercing the shaft oil passage portion 91 b.

If the operation valve is switched to the off position, the hydraulic pressure is supplied from the operation valve to the 1 st operation oil passage 91, the 1 st operation oil passage 91 supplies the supplied hydraulic pressure from the 1 st supply/discharge port 90 to between the outer ring portion 43b and the 1 st hydraulic piston 49, and the 1 st hydraulic piston 49 is operated to the off position against the coned disc spring 39. When the operation valve is switched to the engaged position, the 1 st hydraulic piston 49 is operated to the engaged position by returning the pressure oil between the outer ring portion 43b and the 1 st hydraulic piston 49 to the 1 st operation oil passage 91 through the 1 st supply/discharge port 90, discharging the pressure oil returned to the 1 st operation oil passage 91 to the operation valve, and moving the 1 st hydraulic piston 49 to the engaged position by the coned disc spring 39. That is, the 1 st operation oil passage 91 supplies and discharges hydraulic pressure to switch the front wheel clutch 40 between the on state and the off state.

As shown in fig. 3, a 2 nd supply/discharge port 93 for supplying/discharging the hydraulic pressure between the outer ring portion 63d and the 2 nd hydraulic piston 67 is formed in the sleeve portion 63a of the clutch drum 63 of the front wheel speed increasing clutch 60. The 2 nd supply/discharge port 93 and an operation valve (not shown) provided outside the transmission case 13 are connected via a 2 nd operation oil passage 94 that is bored across the front wheel drive shaft 29 and the center bracket 70B. The 2 nd operation oil passage 94 has: a bracket oil path portion 94a penetrating the middle bracket 70B; and a shaft oil passage portion 94b that is bored in the front wheel propeller shaft 29 from a portion corresponding to the carrier oil passage portion 94a to a portion corresponding to the 2 nd supply/discharge port 93. In the front wheel propeller shaft 29, the shaft hole 95 formed by the end portion of the straddle oil passage portion 94b on the side of the center bracket and the end portion 29c of the front wheel propeller shaft 29 is formed not for the 2 nd operation oil passage 94 but for the penetration of the shaft oil passage portion 94 b.

If the operation valve is switched to the on position, hydraulic pressure is supplied from the operation valve to the 2 nd operation oil passage 94, the 2 nd operation oil passage 94 supplies the supplied hydraulic pressure from the 2 nd supply/discharge port 93 to between the outer ring portion 63d and the 2 nd hydraulic piston 67, and the 2 nd hydraulic piston 67 is operated to the on position against the coil spring 68. When the operation valve is switched to the off position, the pressure oil between the outer ring portion 63d and the 2 nd hydraulic piston 67 is returned to the 2 nd operation oil passage 94 through the 2 nd supply/discharge port 93, the 2 nd operation oil passage 94 discharges the returned pressure oil to the operation valve, and the 2 nd hydraulic piston 67 is operated to the off position by the coil spring 68. That is, the 2 nd operation oil passage 94 supplies and discharges hydraulic pressure to switch the front wheel speed increasing clutch 60 between the on state and the off state.

[ Structure of speed increasing clutch cover ]

As shown in fig. 2, the front wheel speed increasing clutch 60 is disposed in a lower portion of the internal space S of the transmission case 13. A speed increasing clutch cover 100 covering the front wheel speed increasing clutch 60 is provided in the internal space S. As shown in fig. 8, 9, and 10, the speed increasing clutch cover 100 has an opening 100K formed upward. The lubricating oil stored in the transmission case 13 flows into the inside of the speed increasing clutch cover 100 through the opening 100K, and can be stored in the peripheral region of the front wheel speed increasing clutch 60 in the internal space S. The lubricating oil located in the peripheral region of the front wheel speed increasing clutch 60 is stirred by the rotation of the front wheel speed increasing clutch 60, but the stirring of the lubricating oil by the front wheel speed increasing clutch 60 and the lubricating oil located in a region away from the peripheral region of the front wheel speed increasing clutch 60 are suppressed by the speed increasing clutch cover 100.

Specifically, as shown in fig. 5 and 6, the speed increasing clutch cover 100 is disposed between the middle bracket 70B and the rear bracket 70C. The rear portion of the speed increasing clutch cover 100 is coupled to a support portion 87 (see fig. 4) formed on the rear bracket 70C by a coupling bolt, and the speed increasing clutch cover 100 is detachably supported by the rear bracket 70C. As shown in fig. 5 and 6, the speed increasing clutch cover 100 includes a lower cover portion 100D located below the upper end portion 60a of the front wheel speed increasing clutch 60 and an upper cover portion 100U extending upward from the lower cover portion 100D.

As shown in fig. 5, 6, 9, and 10, lower cover portion 100D includes a 1 st lateral wall portion 101 that covers front wheel speed increasing clutch 60 from the right lateral side, a 2 nd lateral wall portion 102 that covers front wheel speed increasing clutch 60 from the left lateral side, a bottom wall portion 103 that covers front wheel speed increasing clutch 60 from below, and a rear wall portion 104 that covers front wheel speed increasing clutch 60 from behind. A lateral cover portion 108 extends from the upper end portion of the 2 nd lateral wall portion 102 toward the lateral outer side of the lower cover portion 100D. The lateral cover portion 108 extends to a lateral wall portion of the transmission case 13, as shown in fig. 7. The space between the 2 nd lateral wall 102 and the transmission case 13 is closed by a lateral cover 108. The bottom wall 103 is formed in an arc shape along the lower portion of the front wheel speed increasing clutch 60. A through hole 105 into which the sleeve portion 81 of the rear bracket 70C is inserted is opened in the rear wall portion 104. As shown in fig. 5 and 7, the upper cover portion 100U extends upward from the 1 st horizontal wall portion 101 to a position higher than the axis X of the rear wheel propeller shaft 27. An upper end 100t of an upper cover portion 100U as an upper end of the speed increasing clutch cover 100 is located higher than the axial center X of the rear wheel propeller shaft 27. As shown in fig. 8 and 9, upper cover 100U and lower cover 100D are formed separately. A coupling portion 106 formed at the lower portion of the upper cover portion 100U and a support portion 107 formed at the 1 st lateral wall portion 101 of the lower cover portion 100D are coupled by a coupling bolt (not shown) attached to the bolt hole 107 a. Upper cover 100U and lower cover 100D are detachably coupled. In the peripheral region of the front wheel speed increasing clutch 60, the speed increasing clutch cover 100 exerts a wave-preventing action on the lubricating oil stirred by the rotation of the front wheel speed increasing clutch 60, and suppresses the stirring wave by the front wheel speed increasing clutch 60 and the lubricating oil in the region located away from the peripheral region of the front wheel speed increasing clutch 60.

An upper end 100t of an upper cover portion 100U as an upper end of the speed increasing clutch cover 100 is located higher than the axial center X of the rear wheel propeller shaft 27. The lubricant oil in the transmission case 13 is generally stored in a state where the oil surface is positioned at or above the axis X of the rear wheel propeller shaft 27, but the flow of the lubricant oil generated by the stirring of the lubricant oil by the front wheel speed increasing clutch 60 and the lubricant oil positioned in a region deviated from the peripheral region of the front wheel speed increasing clutch 60 are effectively suppressed by the upper cover portion 100U.

As shown in fig. 7 and 8, the upper cover portion 100U extends only from the 1 st lateral wall portion 101 out of the 1 st lateral wall portion 101 and the 2 nd lateral wall portion 102. When forward power is transmitted, and as viewed in the direction along the rotation axis Y of the clutch drum 63 of the front wheel speed increasing clutch 60, the right lateral portion 63R of the clutch drum 63 rotates in the upward direction as indicated by the arrow a, the left lateral portion 63L of the clutch drum 63 rotates in the downward direction as indicated by the arrow b, the lubricating oil stirred by the right lateral portion 63R flows upward, and the lubricating oil stirred by the left lateral portion 63L flows downward. The 1 st lateral wall portion 101 of the lower cover portion 100D corresponds to the right lateral portion 63R of the clutch drum 63, and the 2 nd lateral wall portion 102 of the lower cover portion 100D corresponds to the left lateral portion 63L of the clutch drum 63. The upper cover portion 100U extends upward from the 1 st lateral wall portion 101 corresponding to the right lateral wall portion 63R where the upward flow of the lubricating oil occurs, and the upper cover portion 100U effectively acts as a wave-shield against the upward flow of the lubricating oil.

[ Structure of front wheel Clutch housing ]

As shown in fig. 2, the front wheel clutch 40 is disposed in a lower portion of the internal space S of the transmission case 13. A front wheel clutch cover 110 that covers the front wheel clutch 40 is provided in the internal space S. The front wheel clutch cover 110 has an opening 110K formed upward as shown in fig. 11 and 12. The lubricating oil stored in the transmission case 13 flows into the front wheel clutch cover 110 through the opening 110K, and the lubricating oil can be stored in the peripheral region of the front wheel clutch 40 in the internal space S. In the peripheral region of the front wheel clutch 40, the front wheel clutch cover 110 exerts a wave-preventing action on the lubricating oil stirred by the rotation of the front wheel clutch 40, and suppresses the stirring wave by the front wheel clutch 40 and the lubricating oil in the region located away from the peripheral region of the front wheel clutch 40.

Specifically, the front wheel clutch cover 110 is disposed between the front bracket 70A and the center bracket 70B, as shown in fig. 5 and 6. The front portion of the front wheel clutch cover 110 is coupled to the support portion 88 formed on the front bracket 70A by coupling bolts, the rear portion of the front wheel clutch cover 110 is coupled to the support portion 89 (see fig. 4) formed on the middle bracket 70B by coupling bolts, and the front wheel clutch cover 110 is detachably supported by the front bracket 70A and the middle bracket 70B.

As shown in fig. 5, 6, 11, and 12, the front wheel clutch cover 110 includes a lower cover portion 110D located below the upper end portion 40a of the front wheel clutch 40, and an upper cover portion 110U extending upward from a 1 st lateral wall portion 111 and a rear wall portion 115 of the lower cover portion 110D. The upper cover 110U is integrally formed with the 1 st lateral wall 111 and the rear wall 115 of the lower cover 110D. Upper cover portion 110U extends to a position higher than the axial center X of rear wheel transmission shaft 27. An upper end 110t of an upper cover portion 110U as an upper end of the front wheel clutch cover 110 is located higher than the axial core X.

As shown in fig. 5, 6, 11, and 12, the lower cover portion 110D includes a 1 st lateral wall portion 111 that covers the front wheel clutch 40 from the right lateral side, a 2 nd lateral wall portion 112 that covers the front wheel clutch 40 from the left lateral side, a bottom wall portion 113 that covers the front wheel clutch 40 from below, a front wall portion 114 that covers the front wheel clutch 40 from the front, and a rear wall portion 115 that covers the front wheel clutch 40 from the rear. The bottom wall 113 is formed in an arc shape along the lower portion of the front wheel clutch 40. The front wall portion 114 is configured to be detachable from a portion of the lower cover portion 110D other than the front cover portion. A cutout 116 through which the front wheel propeller shaft 29 is inserted is formed in the front wall portion 114. A through hole 117 into which the sleeve portion 73 of the middle bracket 70B enters is opened in the rear wall portion 115. A through hole 118 through which the rear wheel propeller shaft 27 is inserted is opened in the upper cover portion 110U.

[ other embodiments ]

(1) In the above-described embodiment, the upper end 100t of the speed increasing clutch cover 100 and the upper end 110t of the front wheel clutch cover 110 are located higher than the axis X of the rear wheel propeller shaft 27, but the upper end 100t of the speed increasing clutch cover 100 and the upper end 110t of the front wheel clutch cover 110 may be located at the same height as the axis X.

(2) In the above-described embodiment, the example in which the clutch drum 63 as the rotating member of the front wheel speed increasing clutch 60 is supported by the support portion 74 of the center bracket 70B has been described, but a member supporting the clutch hub 62 as the rotating member may be used. The support portion 74 may not be provided.

(3) In the above-described embodiment, the middle bracket 70B and the rear bracket 70C are formed separately from the transmission case 13, but may be formed integrally with the transmission case 13.

(4) In the above-described embodiment, the example in which 2 spacers 86 are provided is shown, but the present invention is not limited to this. The spacer 86 may not be provided. Further, only 1 spacer 86 may be provided, or 3 or more spacers may be provided.

(5) In the above-described embodiment, the example in which the upper cover portions 100U and 110U extend only from the 1 st lateral wall portion of the lower cover portions 100D and 110D has been described, but the upper cover portions may extend from both the 1 st lateral wall portion and the 2 nd lateral wall portion of the lower cover portions 100D and 110D.

(6) In the above-described embodiment, the disc spring 39 that biases the front wheel clutch 40 to the engaged state is used, but the present invention is not limited to this. For example, various urging members such as coil springs can be used.

(7) In the above-described embodiment, the example in which the coil spring 68 that biases the front wheel speed increasing clutch 60 in the disengaged state is used is described, but the present invention is not limited to this. For example, various urging members such as a disc spring can be used.

Industrial applicability

The present invention can be applied to a structure including an electric motor as a power source instead of an engine, or a structure including an engine and an electric motor as power sources.

Description of the reference numerals

1 front wheel

2 rear wheel

4 power source (Engine)

13 gearbox case

21 front wheel differential mechanism

22 rear wheel differential mechanism

23 speed variator

27 rear wheel transmission shaft

29 front wheel transmission shaft

36 Emergency brake

39 1 st force application part (disc spring)

40 front wheel clutch

49 1 st hydraulic piston

54 force transmission member

60 front wheel speed increasing clutch

60a upper end

63 rotating parts (Clutch drum)

67 nd 2 nd hydraulic piston

68 nd 2 nd force applying component (helical spring)

70B support (middle support)

70C No. 2 support (rear support)

77 bearing

79 wall part

84 wall portion

86 spacer

91 st operation oil path

94 nd operation oil circuit

100 speed increasing clutch cover

100K opening

100t upper end

101 1 st lateral wall part

102 nd 2 nd transverse wall part

110 front wheel clutch cover

110K opening

110t upper end

110U upper cover part

X-axis core

And a Y-axis core.