阅读说明：本技术 建筑车辆 (Construction vehicle ) 是由 石田慎二 丰岛健太 于 2018-12-12 设计创作，主要内容包括：本发明的特征在于,具备：行驶用液压泵(P1),其连接于发动机(E)的输出轴,向行驶用液压回路(Z1)供给液压油；振动用液压泵(P2),其连接于发动机(E)的输出轴,向振动用液压回路(Z2)供给液压油；及过旋转抑制机构(30),其在容许转速以上的负载从行驶用液压泵(P1)作用于发动机(E)的输出轴时,使振动用液压泵(P2)工作而抑制发动机(E)的过旋转。(The present invention is characterized by comprising: a traveling hydraulic pump (P1) connected to an output shaft of the engine (E) and configured to supply hydraulic oil to a traveling hydraulic circuit (Z1); a vibration hydraulic pump (P2) connected to the output shaft of the engine (E) and supplying hydraulic oil to a vibration hydraulic circuit (Z2); and an over-rotation suppressing mechanism (30) that, when a load equal to or greater than an allowable rotation speed acts on the output shaft of the engine (E) from the traveling hydraulic pump (P1), operates the vibration hydraulic pump (P2) to suppress over-rotation of the engine (E).)

1. A construction vehicle is characterized by comprising:

a traveling hydraulic pump connected to an output shaft of the engine and configured to supply hydraulic oil to a traveling hydraulic circuit;

a hydraulic pump for work connected to an output shaft of the engine and supplying hydraulic oil to a hydraulic circuit for work; and

and an over-rotation suppressing mechanism that, when a load equal to or greater than an allowable rotation speed acts on an output shaft of the engine from the traveling hydraulic pump, operates the working hydraulic pump to suppress over-rotation of the engine.

2. The construction vehicle according to claim 1,

the construction vehicle is provided with a roller which is provided with an oscillation shaft inside and rolls a rolled surface,

the working hydraulic pump vibrates the roller by rotating the vibration shaft.

3. The construction vehicle according to claim 2,

the over-rotation suppressing mechanism intermittently rotates the oscillation starting shaft in the same direction.

4. The construction vehicle according to claim 2,

the over-rotation suppressing mechanism rotates the oscillation starting shaft in the forward direction and the reverse direction.

5. The construction vehicle according to claim 1,

the allowable rotation speed is set higher than a maximum rotation speed of the engine when the vehicle running at the high idle speed is stopped.

6. The construction vehicle according to claim 1,

the over-rotation suppressing means stops the working hydraulic pump when the over-rotation of the engine is suppressed and the rotation speed of the engine becomes equal to or less than a predetermined rotation speed,

the predetermined rotation speed is set higher than a rotation speed of the engine at a high idle speed.

Technical Field

The present invention relates to a construction vehicle.

Background

As a construction vehicle that travels or stops by a hydrostatic transmission (hst), a construction vehicle of patent document 1 is known.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-279363

Disclosure of Invention

Drawings

Fig. 1 is a side view showing a vibrated roller according to an embodiment of the present invention.

Fig. 2 is a schematic view showing a hydraulic device of a vibratory roller according to the embodiment.

Fig. 3A is a conceptual diagram of a conventional vibrating roller during normal running for explaining the problem of the present invention.

Fig. 3B is a conceptual diagram of a conventional vibratory roller for illustrating the problem of the present invention when over-rotation occurs.

Fig. 3C is a conceptual diagram for explaining the operation and effect of the over-rotation suppressing mechanism according to the present embodiment.

Fig. 4 is a graph in which the number of revolutions of the engine, the number of revolutions of the hydraulic motor for vibration, and the hydraulic pressure of the hydraulic pump for vibration are compared in time series.

Fig. 5 is a conceptual diagram illustrating an example of setting of the over-rotation suppressing mechanism according to the present embodiment.

Fig. 6 is a graph showing the hydraulic pressure of the traveling hydraulic pump, the hydraulic pressure of the vibration hydraulic pump, and the engine speed of the comparative example.

Fig. 7 is a graph showing the hydraulic pressure of the traveling hydraulic pump, the hydraulic pressure of the vibration hydraulic pump, and the engine speed in the embodiment.

Detailed Description

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. As shown in fig. 1, a vibratory roller 1 for civil engineering work is exemplified as a construction vehicle of the present embodiment. The vibrating roller 1 is a compacting machine having a vibrating roller R. The vibratory roller 1 can roll a surface to be rolled by moving forward or backward while vibrating the roller R. In the present embodiment, the vibratory roller 1 is exemplified as a construction vehicle, but the present invention is also applicable to other construction vehicles used at a construction site.

As shown in fig. 1, the vibratory roller 1 mainly includes a base 2, tires T, T, a tire travel motor M1, a machine frame 3, a roller R, a roller travel motor M2, a vibration hydraulic motor M3, a hydraulic device 10 (see fig. 2), and an over-rotation suppressing mechanism 30 (see fig. 2). The tire travel motor M1, the wheel travel motor M2, and the vibration hydraulic motor M3 are hydraulic motors.

As shown in fig. 1, the base body 2 mounts an engine E and rotatably supports a tire T, T via an axle X1. A driver seat 5 having a steering wheel H is provided above the base body 2. A forward/reverse operation lever R1 is provided beside the seat 6 of the driver seat 5. The forward/reverse operation lever R1 is a lever for switching forward or reverse of the vehicle. The forward/reverse lever R1 is located at three positions, i.e., a forward position, a neutral position, and a reverse position. A throttle lever R2 is provided beside the operation panel S of the driver seat 5. The throttle lever R2 is a lever capable of controlling the rotation speed of the engine E according to the degree of tilt.

The operation panel S is provided with a vibration switch S1 for switching on and off of the vibration of the wheel R and a changeover switch S2 for switching forward rotation or reverse rotation of the vibration. The tire travel motor M1 is provided in the vicinity of the axle X1 that supports the tire T, T.

The frame 3 is connected to the base body 2 via a connecting portion 4. The vibrating roller 1 is of a hinge type that can rotate about a vertical axis about the connecting portion 4. The frame 3 supports the roller R to be rotatable and vibratile. A vibrator case is provided inside the roller R, and a vibration axis X2 for vibrating the roller R is provided inside the vibrator case. The roller R can be vibrated by rotating the oscillation axis X2 to which the eccentric weight Y (see fig. 2) is fixed by the vibration hydraulic motor M3. The roller travel motor M2 and the vibration hydraulic motor M3 are provided inside the roller R.

Although not specifically shown, the vibrating roller 1 includes HST brakes for work and travel. Further, a parking brake is also provided for use in parking. It should be noted that the invention can be not only in a hinged type, but also in a rigid frame type, and can also be used as a double-roller road roller, a stone-breaking road roller and the like.

As shown in fig. 2, the hydraulic device 10 of the present embodiment includes a traveling hydraulic circuit Z1 constituting a traveling hydraulic circuit and a vibration hydraulic circuit Z2 constituting a vibration hydraulic circuit. The hydraulic travel circuit Z1 is a closed circuit including a hydraulic travel pump P1, a travel motor M1 for tires, a travel motor M2 for wheels, and a flow path connecting these components.

The traveling hydraulic pump P1 is of a variable displacement type capable of changing the discharge amount, and is connected to the output shaft of the engine E via a shaft joint 11. The vibration hydraulic pump P2 is connected to an output shaft of the engine E. That is, in the present embodiment, the traveling hydraulic pump P1 and the oscillating hydraulic pump P2 are connected in series to the output shaft of the engine E, and the traveling hydraulic pump P1 and the oscillating hydraulic pump P2 rotate in synchronization with each other. In the present embodiment, the traveling hydraulic pump P1 and the oscillating hydraulic pump P2 are directly connected by a spline shaft, but may be indirectly connected via gears or the like.

The traveling hydraulic pump P1 includes a first port Q1 and a second port Q2. The first port Q1 is connected to the first port Q3 of the tire travel motor M1 and the first port Q5 of the wheel travel motor M2, respectively, via flow paths.

The second port Q2 of the travel hydraulic pump P1 is connected to the second port Q4 of the tire travel motor M1 and the second port Q6 of the wheel travel motor M2, respectively, via flow paths. The tire travel motor M1 rotationally drives the tire T, T by the flow of the hydraulic oil. The roller travel motor M2 drives the roller R to rotate by the flow of the hydraulic oil. The direction of the hydraulic fluid flowing through the hydraulic circuit Z1 for traveling can be switched by the hydraulic pump P1 for traveling. This enables the tire T, T and the roller R to rotate in the normal direction (forward movement) or in the reverse direction (backward movement).

The traveling hydraulic pump P1, the tire traveling motor M1, and the wheel traveling motor M2 each have a drain flow path D connected to the hydraulic oil tank 12. The traveling hydraulic pressure circuit Z1 is provided with a relief valve RV for preventing the hydraulic pressure from increasing to a pressure equal to or higher than a set pressure.

The vibration hydraulic circuit Z2 is a closed circuit including a vibration hydraulic pump P2, a vibration hydraulic motor M3, and a flow path connecting these components. The vibration hydraulic pump P2 includes a first port U1 and a second port U2. The first port U1 is connected to the first port U3 of the hydraulic motor for vibration M3 via a flow path. The second port U2 is connected to the second port U4 of the hydraulic motor for vibration M3 via a flow path. The vibration hydraulic motor M3 is connected to a vibration axis X2 that vibrates the roller R, and rotates the vibration axis X2 by the flow of the hydraulic oil. The oscillation hydraulic pressure circuit Z2 is provided with a relief valve RV for preventing the hydraulic pressure from rising to a pressure equal to or higher than a set pressure. The flow direction of the hydraulic fluid in the vibration hydraulic circuit Z2 can be switched by the vibration hydraulic pump P2. This enables the oscillation axis X2 to rotate in the forward direction or the reverse direction.

As shown in fig. 2, the over-rotation suppressing mechanism 30 is a mechanism that automatically suppresses the over-rotation of the engine E. The over-rotation suppressing mechanism 30 is mainly constituted by a sensor 31 for detecting the rotation speed of the engine E and a determination unit 32. The over-rotation suppressing mechanism 30 is electrically connected to the engine E and the vibration hydraulic pump P2. The determination unit 32 is mainly configured to include a calculation unit, an input unit, a storage unit, a display unit, and the like, and transmits an operation signal or a stop signal to the vibration hydraulic pump P2 based on the rotation speed acquired by the sensor 31.

The storage unit of the determination unit 32 is preset with and stores an upper limit value (the "allowable rotation speed" in the claims) for operating the vibration hydraulic pump P2 in accordance with the rotation speed of the engine E detected by the sensor 31 and a lower limit value (the "predetermined rotation speed" in the claims) for stopping the vibration hydraulic pump P2 in accordance with the rotation speed of the engine E detected by the sensor 31. When determining that the detected number of revolutions of the engine E is equal to or greater than the upper limit value, the determination unit 32 sends an operation signal to the vibration hydraulic pump P2. At this time, the vibration hydraulic pump P2 is operated even if the vibration switch S1 is turned off. On the other hand, when the determination unit 32 determines that the detected rotation speed of the engine E is equal to or less than the lower limit value after the operation of the vibration hydraulic pump P2, the determination unit transmits a stop signal to the vibration hydraulic pump P2.

Next, the basic operation of the vibratory roller 1 will be described. When the engine E is started and the driver tilts the throttle lever R2 and tilts the forward/reverse lever R1, the hydraulic pump P1 for traveling is operated. The hydraulic oil flows from the traveling hydraulic pump P1 to the tire traveling motor M1 and the wheel traveling motor M2, and the vehicle is advanced or retracted.

When the driver turns on the vibration switch S1, the vibration hydraulic pump P2 is operated. The hydraulic oil flows from the vibration hydraulic pump P2 to the vibration hydraulic motor M3, and the oscillation axis X2 rotates, whereby the roller R oscillates. The vibration switch S1 is turned off by the driver, whereby the vibration of the wheel R is stopped.

Next, the operation and effect of the over-rotation suppressing mechanism 30 will be described with reference to fig. 3A to 3C. Fig. 3A is a conceptual diagram of a conventional vibrating roller during normal running for explaining the problem of the present invention. Fig. 3B is a conceptual diagram of a conventional vibratory roller for illustrating the problem of the present invention when over-rotation occurs.

As shown in fig. 3A, during normal running of the conventional vibrating roller, power is input from the engine E side to the running hydraulic pump P1, and the running hydraulic pump P1 outputs power to the running motor MA. Arrow F1 indicates the output from the traveling hydraulic pump P1 to the traveling motor MA. The arrow G1 represents the load of the engine E.

Next, as shown in fig. 3B, when the conventional vibrating road roller travels on a downhill, power is input from the traveling motor MA side to the traveling hydraulic pump P1 side due to the lowering of the vehicle, and the engine brake cannot fully support the vehicle, and accordingly the rotation speed of the engine E increases, and the engine E may be over-rotated and damaged. Arrow F2 indicates the output from the traveling motor MA to the traveling hydraulic pump P1. The arrow G2 indicates a state where the load of the engine E rises.

Therefore, according to the present embodiment shown in fig. 3C, although power is input to the traveling hydraulic pump P1 from the tire traveling motor M1 and the wheel traveling motor M2 due to the lowering of the vehicle, the power is consumed as the starting energy of the vibration by operating the vibration hydraulic pump P2 by the over-rotation suppressing mechanism 30, and the power input to the engine E is reduced, and the over-rotation of the engine E is suppressed. Arrow G3 indicates a state in which the oscillating hydraulic pump P2 is driven. An arrow G2 of fig. 3C indicates a state in which the load of the engine E is reduced.

Fig. 4 is a graph in which the rotation speed of the engine E, the rotation speed of the vibration hydraulic motor M3, and the hydraulic pressure of the vibration hydraulic pump P2 of the present embodiment are compared in time series. Fig. 4 schematically shows a state in which the vibrating roller 1 is traveling on a downhill slope and the over-rotation suppressing mechanism 30 is operated. Here, when the rotation speed of the engine E reaches the preset upper limit value (time t1), the vibration hydraulic pump P2 is operated. When the rotation speed of the engine E reaches a preset lower limit value (time t2), the vibration hydraulic pump P2 is stopped. The time for which the vibration hydraulic pump P2 operates is about 1.5 seconds.

Next, when the vehicle travels on a downhill and the rotation speed of the engine E reaches the upper limit value again (time t3), the vibration hydraulic pump P2 is operated again. When the rotation speed of the engine E reaches the lower limit value (time t4), the vibration hydraulic pump P2 is stopped. The second operation time of the vibration hydraulic pump P2 is also about 1.5 seconds.

As shown in the engine speed L1 of fig. 4, when the excessive rotation suppressing mechanism 30 reaches the upper limit value (allowable speed), the vibration hydraulic pump P2 is operated, and therefore the engine speed of the engine E can be reduced. As indicated by the hydraulic pressure L3 of the oscillation hydraulic pump P2, the oscillation energy at the time of oscillating the roller R at time t1 increases greatly. That is, a large amount of energy is required to vibrate the roller R. In the present embodiment, by operating the vibration hydraulic pump P2, the vibration hydraulic pump P2 consumes (takes away) the energy input to the engine E from the tire travel motor M1 and the wheel travel motor M2, and therefore the rotation speed of the engine E can be reduced.

At this time, since the vibration hydraulic pump P2 is immediately stopped, the rotation speed of the vibration hydraulic motor M3 does not increase so much as indicated by the rotation speed L2 of the vibration hydraulic motor M3. That is, the roller R is not substantially vibrated. The driver can feel the sense of deceleration, but does not feel the vibration of the roller R. The rotation speed L2b (dashed line) of the vibration hydraulic motor virtually indicates a state in which the vibration hydraulic motor M3 is continuously operated. Similarly, the hydraulic pressure L3c (dotted line portion) of the vibration hydraulic pump P2 virtually represents a state in which the vibration hydraulic motor M3 is continuously operated.

As in the embodiment of fig. 4, the vibration hydraulic pump P2 can be intermittently rotated in the forward direction to suppress the over-rotation of the engine E. This makes it possible to efficiently reduce the excessive rotation of the engine E even when the vehicle is traveling on a long downhill.

On the other hand, for example, when the downhill path is long and has a steep gradient, the excessive rotation may not be suppressed by simply repeating the forward rotation of the vibration hydraulic pump P2 as in the embodiment of fig. 4. That is, if the gradient is steep, the increase in the rotation speed of the engine E is also rapid, and therefore the hydraulic pressure of the oscillating hydraulic pump P2 has to be increased again before the hydraulic pressure of the oscillating hydraulic pump P2 completely decreases. In such a case, the amount of energy taken away from the engine E is also reduced, and therefore, there is a possibility that the over-rotation of the engine E cannot be efficiently suppressed.

In this case, the excessive rotation suppressing mechanism 30 may be configured to intermittently rotate the vibration hydraulic pump P2 while sequentially changing the rotation direction to the forward rotation → the reverse rotation → the forward rotation → the reverse rotation. As a result, the amount of energy taken away from the engine E can be increased as compared with the case where the normal rotation is intermittently repeated, and therefore, the over-rotation of the engine E can be efficiently suppressed.

Next, an example of setting the upper limit value and the lower limit value of the over-rotation suppressing mechanism 30 will be described. The numerical values are merely examples, and do not limit the present invention. Fig. 5 is a conceptual diagram illustrating an example of setting of the over-rotation suppressing mechanism 30 according to the present embodiment. As shown in fig. 5, in the over-rotation suppressing mechanism 30, the value for operating the vibration hydraulic pump P2 ("allowable rotation speed" (upper limit)) is preferably lower than "rotation speed at which the engine may be damaged due to overload (e.g., 3000 rpm)" and higher than "rotation speed at which the vehicle is stopped (e.g., 2400 rpm)". The "rotation speed at the time of vehicle stop" is a maximum value when the rotation speed of the engine E is instantaneously increased by a load applied to the engine E when the vibrating roller 1 traveling at the high idle speed on a flat road is stopped. The upper limit value is preferably set higher than "the rotation speed at the time of stopping the vehicle". That is, it is preferable to avoid the vibration hydraulic pump P2 from being operated via the over-rotation suppressing mechanism 30 in a range where the vibrating roller 1 is normally used.

On the other hand, in the over-rotation suppressing mechanism 30, the value ("predetermined rotation speed" (lower limit)) for stopping the vibration hydraulic pump P2 is preferably lower than the "allowable rotation speed" and higher than the "high idle speed". Since the roller R is normally vibrated when the operation of the vibration hydraulic pump P2 is continued, the lower limit value of the over-rotation suppressing mechanism 30 is set to prevent the vibration. The "high idle" state is a state of the engine E in which the throttle lever R2 is most tilted. Since the tamper roller 1 normally travels with the throttle lever R2 most tilted (throttle fully open), if the lower limit value is set lower than the "high idle" time, the rotation speed of the engine E does not decrease from the rotation speed at the "high idle" time, and therefore the vibration hydraulic pump P2 continues to operate. However, by setting the lower limit higher than the "high idle" as in the present embodiment, the vibration hydraulic pump P2 can be reliably stopped.

The values of the upper limit value and the lower limit value of the over-rotation suppressing mechanism 30 may be appropriately set according to the matching of the type of the construction vehicle, the type of the engine E, the type of the vibration hydraulic pump P2, the rotation torque of the roller R, the gradient of the expected slope road, and the like. The values of the upper limit value and the lower limit value of the over-rotation suppressing mechanism 30 are preferably set as appropriate within the following ranges: the over-rotation of the engine E is reliably suppressed, the driver does not feel vibrations, and an excessive load (inertial force) does not act on the driver when the over-rotation is suppressed.

According to the vibrating roller 1 of the present embodiment described above, the power input to the engine E can be reduced by operating the vibration hydraulic pump P2 (work hydraulic pump) to consume power as starting energy, and thus, the over-rotation of the engine E can be suppressed. Further, since the existing vibration hydraulic pump P2 only needs to be operated, a simple configuration can be achieved.

Further, since the over-rotation suppressing mechanism 30 has a simple structure including the sensor 31 and the determination unit 32, the manufacturing cost can be reduced, and the mounting space can be reduced. Further, the over-rotation suppressing mechanism 30 can be easily attached to the existing vibrated roller 1 by post-installation.

The type of the working hydraulic pump may be set as appropriate, and in the present embodiment, the working hydraulic pump is a vibration hydraulic pump P2 that vibrates the roller R. Since a large amount of energy is required to vibrate the roller R, the large amount of energy can be consumed on the vibration hydraulic pump P2 side, and the over-rotation of the engine E can be effectively suppressed. Further, for example, when the working hydraulic pump is a hydraulic pump for driving an arm of the backhoe, the arm may move in an unexpected situation. However, in the present embodiment, since the vibration energy can be dissipated inside the roller R, the adverse effect on the outside can be reduced as much as possible.

Although the embodiments of the present invention have been described above, the present invention can be appropriately modified in design within a range not departing from the gist of the present invention. For example, in the present embodiment, the vibration hydraulic pump P2 is used as the working hydraulic pump, but the present invention is not limited thereto. For example, a pump for sprinkling water, a cutter head, or other hydraulic pump for work provided in the construction vehicle may be used.

In the present embodiment, the roller R is a single shaft, but may be a double shaft. Although the over-rotation suppressing mechanism 30 is directly connected to the vibration hydraulic pump P2, an electromagnetic valve may be provided in the vibration hydraulic circuit Z2, and the vibration hydraulic pump P2 may be controlled by the electromagnetic valve. In the present embodiment, the vibrating roller 1 including the roller R and the tire T, T is exemplified, but may be a two-wheeled roller R or a two-wheeled tire T, T. Further, a notification mechanism may be provided for notifying the outside by sound, light, or the like while the over-rotation suppressing mechanism 30 is operating. The vibration hydraulic pump P2 may be of a variable displacement type in which the discharge amount can be changed, or may be of a fixed displacement type in which the discharge amount is not changed.