阅读说明：本技术 变速器的油压电路 (Hydraulic circuit of transmission ) 是由 韮泽英夫 于 2019-07-23 设计创作，主要内容包括：本发明提供一种变速器的油压电路,能够一方面防止供给至控制对象的油压不足,一方面有效地抑制高压模式与低压模式的切换频繁而产生的振荡现象。所述变速器的油压电路包括：单向阀(V8),插装于主泵(PM)与副泵(PS)之间,当副泵(PS)的喷出压力高于主泵(PM)的喷出压力时开阀；以及第四油路(L4),被供给主泵(PM)及副泵(PS)的喷出压力；并且通过电磁阀(V5)导通,或者第四油路(L4)的油压成为规定值以下,来切断由切换阀(V2)切换的第一油路(L1)与第二油路(L2)的连通,另一方面,只通过电磁阀(V5)断开而使由切换阀(V2)切换的第一油路(L1)与第二油路(L2)连通。(The invention provides a hydraulic circuit of a transmission, which can prevent the shortage of the hydraulic pressure supplied to a controlled object and effectively inhibit the oscillation phenomenon generated by frequent switching between a high-pressure mode and a low-pressure mode. The oil pressure circuit of the transmission includes: a check valve (V8) interposed between the main Pump (PM) and the sub Pump (PS), and opened when the discharge pressure of the sub Pump (PS) is higher than the discharge pressure of the main Pump (PM); and a fourth oil passage (L4) to which discharge pressures of the main Pump (PM) and the sub Pump (PS) are supplied; when the solenoid valve (V5) is turned on or the hydraulic pressure of the fourth oil passage (L4) is equal to or less than a predetermined value, the communication between the first oil passage (L1) and the second oil passage (L2) switched by the switching valve (V2) is cut off, and the first oil passage (L1) and the second oil passage (L2) switched by the switching valve (V2) are communicated only by turning off the solenoid valve (V5).)

1. An oil pressure circuit of a transmission is provided,

comprises a main pump and a secondary pump, and

the oil discharged from the main pump is supplied to at least a first oil supply destination, and

a state in which the oil discharged from the sub pump can be supplied to a second oil supply destination and a state in which the oil discharged from the main pump can be supplied to the first oil supply destination together with the oil discharged from the sub pump can be selected,

the first oil supply destination is an oil supply destination having a pressure higher than that of the second oil supply destination,

the oil pressure circuit of the transmission includes:

a switching valve that switches communication/non-communication between a first oil passage connected to the sub pump and a second oil passage connected to the second oil supply destination;

a solenoid valve that operates the switching valve to a position at which communication between the first oil passage and the second oil passage is cut off;

a third oil passage connecting the main pump and the sub pump;

a check valve inserted into the third oil passage and opened when the discharge pressure of the sub-pump is higher than that of the main pump; and

a fourth oil passage to which discharge pressures of the main pump and the sub pump are supplied; and is

The hydraulic circuit of the transmission is configured to:

the solenoid valve is turned on, or the hydraulic pressure of the fourth oil passage becomes a predetermined value or less, and the communication between the first oil passage and the second oil passage of the selector valve is cut off,

the first oil passage and the second oil passage of the switching valve are communicated only by the solenoid valve being turned off.

2. The oil pressure circuit of a transmission according to claim 1,

the first oil supply destination includes a shift control system for performing shift control of the transmission,

the second oil supply destination includes a lubrication system that supplies oil to a lubrication target.

3. The oil pressure circuit of a transmission according to claim 1 or 2,

the oil pressure circuit can realize that:

a low-pressure mode in which the first oil passage and the second oil passage are communicated with each other via the switching valve; and a high-pressure mode in which communication between the first oil passage and the second oil passage is cut off;

as the high-pressure mode, it is possible to realize:

a first high-pressure mode in which the communication between the first oil passage and the second oil passage is cut off by switching on/off of the solenoid valve; and

a second high-pressure mode in which communication between the first oil passage and the second oil passage is blocked by a change in oil pressure of the fourth oil passage;

the transition from the second high-pressure mode to the low-pressure mode is a transition to the first high-pressure mode by switching the solenoid valve from off to on in the second high-pressure mode, and then a transition to the low-pressure mode by switching the solenoid valve from on to off in the first high-pressure mode.

4. The oil pressure circuit of a transmission according to claim 2 or 3,

the switching valve includes:

a valve element which moves forward and backward;

a force application component which applies force to the valve core towards one side;

a first port to which a predetermined pressure of the hydraulic circuit is supplied;

a second port to which the oil pressure of the fourth oil passage is supplied; and

a third port to which an output pressure of the solenoid valve is supplied; and is

When a force applied to the spool by the oil pressure of the second port is smaller than a resultant force of a force applied by the force application member and a force applied to the spool by the oil pressure of the first port, the spool moves toward a position where communication between the first oil passage and the second oil passage is cut off.

5. The oil pressure circuit of a transmission according to claim 4, characterized by comprising:

a step portion formed on the valve element; and is

When the spool is located at a position where communication between the first oil passage and the second oil passage is cut off, the oil pressure of the first port acts on the step portion.

6. The oil pressure circuit of a transmission according to claim 1 or 2,

the fourth oil passage is an oil passage that communicates with the torque converter,

the hydraulic pressure of the fourth oil passage is an internal pressure of the torque converter.

7. The oil pressure circuit of a transmission according to any one of claims 1 to 5,

the sub-pump has a lower discharge pressure and a larger discharge flow rate than the main pump.

Technical Field

The present invention relates to a hydraulic circuit for a transmission, and more particularly, to a hydraulic circuit for a transmission including a main pump and a sub pump (sub pump), configured to supply oil discharged from the main pump to a shift control system and supply oil discharged from the sub pump to a lubrication system.

Background

Conventionally, as a hydraulic circuit of a transmission mounted on a vehicle, for example, as shown in patent document 1, there is a hydraulic circuit in which oil is supplied to a pulley oil chamber, a torque converter (torque converter), and a lubrication system of the transmission by a main pump and a sub pump driven simultaneously by an engine. In the hydraulic circuit disclosed in patent document 1, a low-pressure mode (lubrication mode) in which the discharge pressure of the sub-pump is supplied to the lubrication system and a high-pressure mode in which the discharge pressure of the sub-pump and the discharge pressure of the main pump are merged can be switched by switching a pump shift valve (pump shift valve). When the discharge flow rate of the main pump is insufficient and the hydraulic pressure of the torque converter or the lubrication system is reduced at the time of sudden acceleration or sudden deceleration of the vehicle, the supply destination of the oil discharged from the sub-pump is switched in order of the pulley oil chamber, the torque converter, and the lubrication system by switching from the low-pressure mode to the high-pressure mode.

In the hydraulic circuit described in patent document 1, the pump shift valve is switched, and the solenoid valve is turned off (solenoid valve off), and the internal pressure of the torque converter is equal to or higher than a predetermined pressure. Therefore, even in a low-pressure mode command such as an open/close failure of the solenoid valve, the switching function automatically operates in a state where the line pressure is insufficient, and the pump shift valve controls the discharge destination of the sub-pump to secure the line pressure.

However, if the switching conditions between the high-pressure mode and the low-pressure mode are fixed as described above, there is a possibility that a so-called hunting phenomenon occurs in which the low-pressure mode and the high-pressure mode are frequently switched. That is, there is a possibility that the following process is repeated: the internal pressure of the transient torque converter decreases → the automatic switch to the high-pressure mode → the line pressure is sufficient and the internal pressure of the torque converter is restored → the switch to the low-pressure mode is automatic → the internal pressure of the transient torque converter decreases.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent No. 6148354 publication

Disclosure of Invention

[ problems to be solved by the invention ]

The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydraulic circuit for a transmission, which can effectively suppress hunting phenomenon that frequently occurs when a high-pressure mode and a low-pressure mode are switched due to a fluctuation in hydraulic pressure while preventing a shortage of hydraulic pressure supplied to a control target including a shift control system or a lubrication system.

[ means for solving problems ]

In order to achieve the above object, a hydraulic circuit of a transmission according to the present invention is a hydraulic circuit 100 of a transmission including a main pump PM and a sub-pump PS, and capable of selecting a state in which oil discharged from the main pump PM is supplied to at least a first oil supply destination 102 and a state in which oil discharged from the sub-pump PS is supplied to a second oil supply destination 103 and a state in which the oil is supplied to the first oil supply destination 102 together with oil discharged from the main pump PM. The first oil supply destination 102 is an oil supply destination having a higher pressure than the second oil supply destination 103, and the hydraulic circuit 100 of the transmission includes: a switching valve V2 that switches communication/non-communication between a first oil passage L1 connected to the sub pump PS and a second oil passage L2 connected to the second oil supply destination 103; a solenoid valve V5 that operates the switching valve V2 to a position that shuts off communication between the first oil passage L1 and the second oil passage L2; a third oil passage L3 that connects the main pump PM and the sub pump PS; a check valve V8 interposed in the third oil passage L3 and opened when the discharge pressure of the sub pump PS is higher than the discharge pressure of the main pump PM; and a fourth oil passage L4 to which discharge pressures of the main pump PM and the sub pump PS are supplied; the hydraulic circuit 100 of the transmission is configured to shut off the communication between the first oil passage L1 and the second oil passage L2 of the selector valve V2 when the solenoid valve V5 is turned on or the hydraulic pressure of the fourth oil passage L4 is equal to or less than a predetermined value, and to communicate between the first oil passage L1 and the second oil passage L2 of the selector valve V2 only when the solenoid valve V5 is turned off. In this case, the first oil supply destination 102 may include a gear shift control system 102 for controlling a gear shift of the transmission T, and the second oil supply destination 103 may include a lubrication system 103 for supplying oil to a lubrication target.

According to the hydraulic circuit of the transmission of the present invention, the first oil passage and the second oil passage of the switching valve communicate with each other to set the low pressure mode (lubrication mode) in which the discharge pressure of the sub-pump is supplied to the second oil supply destination (lubrication system) which is the oil supply destination having a relatively low pressure, while the first oil passage and the second oil passage do not communicate with each other to raise the discharge pressure of the sub-pump, the check valve opens, and the discharge pressure of the sub-pump and the discharge pressure of the main pump merge and are supplied to the high pressure mode (shift control system) which is the first oil supply destination having a relatively high pressure. The high-pressure mode and the low-pressure mode can be switched by switching the connection/disconnection between the first oil passage and the second oil passage of the switching valve by turning on/off the solenoid valve, and the switching from the low-pressure mode to the high-pressure mode can be performed (automatically) by cutting off the connection between the first oil passage and the second oil passage when the oil pressure of the fourth oil passage becomes equal to or less than a predetermined value. Thus, the hydraulic circuit can effectively prevent the shortage of the hydraulic pressure supplied to the control target including the first oil supply destination (the shift control system) as the oil supply destination having the higher pressure and the second oil supply destination (the lubrication system) as the oil supply destination having the lower pressure.

On the other hand, the high-pressure mode is once set, and then the high-pressure mode is returned to the low-pressure mode only by opening the solenoid valve, and the hydraulic pressure in the fourth oil passage is returned to a hydraulic pressure exceeding a predetermined value, and thus the low-pressure mode is not (automatically) returned to the low-pressure mode, whereby a hunting phenomenon that the high-pressure mode and the low-pressure mode are frequently switched due to a variation in the hydraulic pressure in the fourth oil passage can be effectively suppressed. Therefore, it is possible to prevent the oil pressure supplied to the control target from being insufficient, and to avoid the oscillation of switching between the high-pressure mode and the low-pressure mode.

Further, it is also possible to: the hydraulic circuit 100 is capable of realizing a low pressure mode in which the first oil passage L1 and the second oil passage L2 are communicated with each other via the switching valve V2, and a high pressure mode in which the first oil passage L1 and the second oil passage L2 are blocked from each other, and is capable of realizing, as the high pressure mode, a first high pressure mode in which the communication between the first oil passage L1 and the second oil passage L2 is blocked by switching on/off of the solenoid valve V5, and a second high pressure mode in which the communication between the first oil passage L1 and the second oil passage L2 is blocked by a change in oil pressure of the fourth oil passage L4, and the shift from the second high pressure mode to the low pressure mode is a shift from the first high pressure mode to the second high pressure mode by switching the solenoid valve V5 from off to on in the second high pressure mode, then, the low-pressure mode is shifted to by switching the solenoid valve V5 from on to off in the first high-pressure mode.

According to the above configuration, the transition from the second high-pressure mode to the low-pressure mode, which is achieved by the decrease in the hydraulic pressure of the fourth oil passage, is performed by switching the solenoid valve from off to on in the second high-pressure mode to shift to the first high-pressure mode, and then switching the solenoid valve from on to off in the first high-pressure mode to shift to the low-pressure mode, so that the transition from the second high-pressure mode to the low-pressure mode is not performed unless the solenoid valve is turned on/off. Accordingly, when the hydraulic pressure of the fourth oil passage is decreased to (automatically) shift to the high-pressure mode (second high-pressure mode), the hydraulic pressure of the fourth oil passage is not (automatically) returned to the low-pressure mode even after the hydraulic pressure is restored, and therefore, the hunting between the high-pressure mode and the low-pressure mode can be more effectively prevented.

Further, the switching valve V2 may be configured to: the valve element includes a spool (spool)62 that moves forward and backward, a biasing member 61 that biases the spool 62 in one direction, a first port (port) P21 to which a predetermined pressure of the hydraulic circuit 100 is supplied, a second port P22 to which a hydraulic pressure of the fourth oil passage L4 is supplied, and a third port P23 to which an output pressure of the solenoid valve V5 is supplied, and when a force applied to the spool 62 by the hydraulic pressure of the second port P22 is smaller than a resultant force of a force applied by the biasing member 61 and a force applied to the spool 62 by the hydraulic pressure of the first port P21, the spool 62 moves to a position where communication between the first oil passage L1 and the second oil passage L2 is blocked.

In this case, the following structure may be adopted: a step portion 62b is included that is formed in the valve spool 62, and when the valve spool 62 is located at a position where the communication between the first oil passage L1 and the second oil passage L2 is cut off, the oil pressure of the first port P21 acts on the step portion 62 b.

According to the above configuration, when the oil pressure of the fourth oil passage is decreased to (automatically) shift to the high-pressure mode (second high-pressure mode) in which the communication between the first oil passage and the second oil passage is blocked, even if the oil pressure of the fourth oil passage is thereafter restored, the oil pressure of the first port acts on the step portion of the spool, so that the spool cannot (automatically) return to the position in which the first oil passage and the second oil passage are communicated. Therefore, the second high-pressure mode is not automatically returned to the low-pressure mode, and therefore, the oscillation of the high-pressure mode and the low-pressure mode can be prevented with a simple configuration.

The fourth oil passage L4 may be an oil passage communicating with a torque converter TC, and the hydraulic pressure of the fourth oil passage L4 may be an internal pressure of the torque converter TC.

According to the above configuration, the hydraulic pressure of the fourth oil passage is the internal pressure of the torque converter, and thus, it is possible to prevent the hunting phenomenon in which the high-pressure mode and the low-pressure mode are switched, which occurs particularly with an excessive decrease in the internal pressure of the torque converter. Specifically, the internal pressure of the torque converter is restored and the internal pressure of the torque converter is automatically switched to the low-pressure mode in response to a transient decrease in the internal pressure of the torque converter, so that the internal pressure of the torque converter can be effectively prevented from being lowered again.

The sub pump PS may be a pump having a lower discharge pressure and a larger discharge flow rate than the main pump PM.

According to the above configuration, the discharge pressure of the sub-pump mainly responsible for lubrication is low and the discharge flow rate is large, and the discharge pressure of the main pump mainly responsible for shift control is high and the discharge flow rate is small, so that the total drive load of the hydraulic source of the transmission can be reduced.

The reference numerals in the drawings denote corresponding components in the embodiments described below, and are referred to by reference numerals.

[ Effect of the invention ]

According to the hydraulic circuit of a transmission of the present invention, it is possible to effectively suppress hunting that frequently occurs when switching between a high-pressure mode and a low-pressure mode due to fluctuations in the hydraulic pressure while preventing a shortage of the hydraulic pressure supplied to a control target including a shift control system or a lubrication system.

Drawings

Fig. 1 is a longitudinal sectional view of the belt type continuously variable transmission mechanism.

Fig. 2 is a diagram showing a hydraulic circuit of a transmission according to an embodiment of the present invention.

Fig. 3(a) to 3(c) are diagrams for explaining criteria for determining switching between the high-pressure mode and the circulation mode of the hydraulic circuit.

Fig. 4 is a diagram showing the flow of oil in the high-pressure mode (forced).

Fig. 5 is a diagram showing the flow of oil in the lubrication mode when the initial pressure of the torque converter is sufficient.

Fig. 6 is a diagram showing the flow of oil in the lubrication mode when the initial pressure of the torque converter starts to decrease.

Fig. 7 is a diagram showing the flow of oil in the high-pressure mode (automatic).

Fig. 8(a) to 8(c) are views for explaining switching from the high-pressure mode (automatic) to the lubrication mode.

Fig. 9 is a diagram for explaining switching of the high-pressure mode (forced), the high-pressure mode (automatic), and the lubrication mode of the hydraulic circuit.

Description of the symbols

11: transmission housing

12: torque converter shell

13: transmission housing body

14: input shaft

15: driving pulley shaft

16: driven pulley shaft

17: idle shaft

18: crank shaft

19. TC: torque converter

20: clutch for forward movement

21: forward drive gear

22: forward driven gear

23: clutch for reverse drive

24: driven gear for backward movement

25: idler gear

26: drive gear for backward movement

27: driving pulley

27a, 28 a: pulley oil chamber

28: driven pulley

29: metal strip

30: final drive gear

31: differential gear

32: final driven gear

33. 33: axle shaft

41. 51, 71: spring

42. 52, 62, 72: valve core

42a, 52a, 62a, 72 a: groove

61: spring/force application assembly

62 b: step difference part

100: hydraulic circuit

101: oil groove

102: shift control System/first oil supply destination

103: lubrication system/second oil supply destination

201: lubrication mode

202: high pressure mode (force)

203: high pressure mode (automatic)

211. 212, 213, 214, 215: route of travel

A. B, C: region(s)

L1: first oil path

L2: second oil path

L3: third oil path

L4: fourth oil path

L5: fifth oil path

L6: sixth oil path

L7: seventh oil path

L8: eighth oil passage

L9: ninth oil path

L10: tenth oil passage

P, P1: oil pressure

P11, P21, P31, P41: first port

P12, P22, P32, P42: second port

P13, P26, P33: feedback port

P23, P43: third port

P24, P44: fourth port

P25: the fifth port

PM: main pump

PS: auxiliary pump

t, t 1: oil temperature

T: belt type stepless speed changer

V1: control valve/main control valve

V2: shift valve/switching valve

V3: pressure reducing valve of clutch

V4: shift stop valve

V5: electromagnetic valve

V6: TC regulating valve

V8: one-way valve

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a longitudinal sectional view of a belt type continuously variable transmission mechanism as one embodiment of a transmission of the present invention. First, the overall structure of the belt type continuously variable transmission T will be described with reference to fig. 1. A transmission case 11 of the belt type continuously variable transmission T includes a torque converter case 12 coupled to an engine (not shown) and a transmission case body 13 coupled to the torque converter case 12, and an input shaft 14, a drive pulley shaft (drive pulley shaft)15, a driven pulley shaft (drive pulley shaft)16, and an idle shaft (idle shaft)17 are supported in parallel in the transmission case 11.

An advance drive gear 21 is relatively rotatably supported by an input shaft 14 connected to a crankshaft 18 of an engine via a torque converter 19, and is engageable with the input shaft 14 via an advance clutch 20, and the advance drive gear 21 is engaged with an advance driven gear 22 fixedly provided to a drive pulley shaft 15. A reverse driven gear 24 is relatively rotatably supported by the drive pulley shaft 15 and is engageable with the drive pulley shaft 15 via a reverse clutch 23, and the reverse driven gear 24 is engaged with a reverse drive gear 26 fixed to the input shaft 14 via an idler gear 25 supported by the idler shaft 17.

The driving pulley 27 supported by the driving pulley shaft 15 and the driven pulley 28 supported by the driven pulley shaft 16 are connected by a metal belt 29, and the ratio (ratio) between the driving pulley shaft 15 and the driven pulley shaft 16 can be changed by controlling the hydraulic pressure supplied to the pulley oil chamber 27a of the driving pulley 27 and the pulley oil chamber 28a of the driven pulley 28 and changing the groove widths of the driving pulley 27 and the driven pulley 28.

The final drive gear 30 fixed to the driven pulley shaft 16 meshes with a final driven gear 32 fixed to a housing of the differential gear 31, and left and right axles 33 and 33 extend from the differential gear 31 to the outside of the transmission housing 11.

Therefore, when the forward clutch 20 is engaged and the reverse clutch 23 is disengaged, the driving force of the engine is transmitted to the drive wheels through the path of the crankshaft 18 → the torque converter 19 → the input shaft 14 → the forward clutch 20 → the forward drive gear 21 → the forward driven gear 22 → the drive pulley shaft 15 → the drive pulley 27 → the metal belt 29 → the driven pulley 28 → the driven pulley shaft 16 → the final drive gear 30 → the final driven gear 32 → the differential gear 31 → the axle 33, and the vehicle travels forward.

When the forward clutch 20 is disengaged and the reverse clutch 23 is engaged, the driving force of the engine is transmitted to the driving wheel in a reverse rotation manner in a path of the crankshaft 18 → the torque converter 19 → the input shaft 14 → the reverse drive gear 26 → the idle gear 25 → the reverse driven gear 24 → the reverse clutch 23 → the drive pulley shaft 15 → the drive pulley 27 → the metal belt 29 → the driven pulley 28 → the driven pulley shaft 16 → the final drive gear 30 → the final driven gear 32 → the differential gear 31 → the axle 33, and the vehicle travels in the reverse direction.

In either of the forward travel and the reverse travel, if the groove width of the driving pulley 27 is decreased and the groove width of the driven pulley 28 is increased, the ratio between the driving pulley shaft 15 and the driven pulley shaft 16 is steplessly increased and the vehicle speed is decreased, and conversely, if the groove width of the driving pulley 27 is increased and the groove width of the driven pulley 28 is decreased, the ratio between the driving pulley shaft 15 and the driven pulley shaft 16 is steplessly decreased and the vehicle speed is increased.

Fig. 2 is a diagram showing a hydraulic circuit of a transmission according to an embodiment of the present invention. The hydraulic circuit 100 shown in fig. 2 includes a main pump PM and a sub-pump PS driven by an engine as a drive source of the belt type continuously variable transmission T. The main pump PM mainly used for speed change has a characteristic set such that the discharge pressure is high and the discharge flow rate is small, and the sub pump PS mainly used for lubrication has a characteristic set such that the discharge pressure is low and the discharge flow rate is large. This can reduce the total drive load of the hydraulic source of the belt type continuously variable transmission T.

The oil pumped up by the main pump PM from the oil sump 101 is supplied to the sixth oil passage L6, and is supplied from the sixth oil passage L6 to a regulator valve V1. The oil from the regulator valve V1 is supplied to a Torque Converter (TC) regulator valve V6 via a fourth oil passage L4 at the initial pressure of the torque converter TC, and is regulated by a TC regulator valve V6 and supplied to the torque converter TC. The oil from the regulator valve V1 is supplied from the fifth oil passage L5 to a transmission control system 102 (a first oil supply destination of the present invention: an oil supply destination of high pressure) of the transmission T such as an oil chamber of a clutch or an oil chamber of a pulley via a clutch pressure-reducing valve V3.

The oil pumped up from the oil reservoir 101 by the sub-pump PS is supplied to the first oil passage L1, supplied from the first oil passage L1 to the shift valve (switching valve) V2, supplied from the shift valve V2 to the torque converter TC via the fourth oil passage L4 and the TC regulator valve V6, and supplied to the lubrication system (second oil supply destination: low-pressure oil supply destination of the present invention) 103 such as each bearing of the belt type continuously variable transmission T via the second oil passage L2.

The sixth oil passage L6 and the first oil passage L1 are connected via a third oil passage L3, and a check valve V8 is disposed in the third oil passage L3. The check valve V8 constantly blocks the flow of oil from the sixth oil passage L6 to the first oil passage L1, and opens when the discharge pressure of the sub pump PS is higher than the discharge pressure of the main pump PM to allow the flow of oil from the first oil passage L1 to the sixth oil passage L6.

The regulator valve V1 includes a valve body 52 biased leftward by a spring 51, and a groove 52a formed in the valve body 52, and a first port P11, a second port P12, and a feedback port P13 formed to face the outer peripheral surface of the valve body 52. The first port P11 is connected to the sixth oil passage L6 and the fifth oil passage L5, the feedback port P13 is connected to the clutch pressure-reducing valve V3 via the fifth oil passage L5, and the second port P12 is connected to the second port P22 and the feedback port P26 of the shift valve V2 via the fourth oil passage L4.

The clutch pressure reducing valve V3 includes a valve spool 72 biased rightward by a spring 71, a groove 72a is formed in the valve spool 72, and a first port P31 and a second port P32 facing the outer peripheral surface of the valve spool 72 and a feedback port P33 are formed. The first port P31 is connected to the regulator valve V1 via a fifth oil passage L5, the second port P32 and the feedback port P33 are connected to the shift control system 102 via a tenth oil passage L10, and are connected to a shift inhibitor valve V4 and a shift valve V2 via a ninth oil passage L9.

The shift valve V2 includes a valve body 62 biased rightward by a spring 61, and a groove 62a is formed in the valve body 62, and a first port P21, a second port P22, a third port P23, a fourth port P24, a fifth port P25, and a feedback port P26 are formed to face the outer peripheral surface of the valve body 62. The first port P21 is connected to the shift prevention valve V4 via an eighth oil passage L8, the second port P22 and the feedback port P26 are connected to a fourth oil passage L4, the third port P23 is connected to the conduction/disconnection type solenoid valve V5 via a seventh oil passage L7 and a third port P43 of the shift prevention valve V4, the fourth port P24 is connected to the second oil passage L2, and the fifth port P25 is connected to the sub pump PS via a first oil passage L1.

The shift prevention valve V4 includes a valve body 42 biased to the right by a spring 41, a groove 42a is formed in the valve body 42, and a first port P41, a second port P42, a third port P43, and a fourth port P44 facing the outer peripheral surface of the valve body 42 are formed. The first port P41 is connected to the eighth oil passage L8, the second port P42 is connected to the clutch pressure reducing valve V3 via a ninth oil passage L9, and the third port P43 is connected to the solenoid valve V5 via a seventh oil passage L7. The fourth port P44 is a drain port (drain port), and although not shown, an orifice (orifice) for restricting the flow rate of oil discharged from the fourth port P44 is provided in the oil passage connected to the fourth port P44.

In the hydraulic circuit 100 having the above-described configuration, a high-pressure mode in which both the oil discharged from the main pump PM and the oil discharged from the sub-pump PS are supplied to the speed change control system 102 and a lubrication mode (low-pressure mode) in which the oil discharged from the main pump PM is supplied to the speed change control system 102 and the oil discharged from the sub-pump PS is supplied to the lubrication system 103 can be switched. In addition, the high-pressure mode includes two modes, namely, a high-pressure mode (forced) and a high-pressure mode (automatic). Details regarding the two high pressure modes will be described later. Fig. 3(a) to 3(c) are views for explaining the judgment of the switching between the high-pressure mode and the lubrication mode. The switching between the high-pressure mode and the lubrication mode is performed using "high-pressure mode fixation determination", "traveling state determination", and "flow rate balance determination" described later.

Fig. 3(a) is a diagram showing a graph for "high-pressure mode fixation determination", and is a graph showing a relationship between the oil temperature t and the oil pressure P. In the "high-pressure mode fixing determination", as shown in the graph of fig. 3 a, the high-pressure mode is fixed in a region (high-oil-pressure high-pressure mode fixing region) a where a larger flow rate is required, that is, a region of high oil pressure (oil pressure P > oil pressure P1), and a region (extremely low-temperature high-pressure mode fixing region) B where the responsiveness of the continuously variable transmission mechanism T is deteriorated, that is, an extremely low temperature (oil temperature T < oil temperature T1). In the other region C, switching between the high-pressure mode and the lubrication mode is performed by the flow rate break-off condition.

In the "running state determination", as shown in fig. 3(b), when there is an operation for estimating that an excessive flow rate is required, the high-pressure mode is set in advance and fixed in the high-pressure mode. As an example of such an operation, fig. 3(b) shows a case where the shift speed of the transmission is a speed other than the D-speed (traveling speed), an accelerator off (accelerator off), a kickdown (kickdown), a semi-manual shift mode, a manual shift (manual shift), a stall (stall), and a lock-up clutch (LC) slip. When the voltage falls within any of these cases, the high-voltage mode is set to be fixed.

In the "flow rate balance determination", when it is determined that switching is permitted in the high-pressure mode fixation determination and the traveling state determination, the flow rate balance is calculated only for the case of the oil (flow rate) discharged from the main pump PM. Specifically, the main pump discharge amount is set as a supply amount, the sum of the oil consumption amount of the torque converter, the leakage amount, the oil consumption amount at the time of speed change, and the like is set as a consumption amount, and when the supply amount sufficiently exceeds the consumption amount (when the supply amount is sufficient), the mode is switched to the lubrication mode.

Fig. 4 is a hydraulic circuit diagram showing the flow of oil in the high-pressure mode (forced). In the high-pressure mode (forced), the solenoid valve V5 is turned on. Further, the initial pressure (internal pressure) of the torque converter TC (the oil pressure applied to the shift valve V2 via the fourth oil passage L4) may be in either a sufficient state or a depressed state. In this state, the output pressure (discharge pressure) of the solenoid valve V5 acts on the third port P23 of the shift valve V2, thereby biasing the valve spool 62 of the shift valve V2 toward the right in fig. 4. At this time, if the output pressure of the solenoid valve V5 applied to the valve spool 62 is Fsol, the biasing force of the spring 61 applied to the valve spool 62 is Fspg, and the initial pressure of the torque converter TC applied to the valve spool 62 via the fourth oil passage L4 and the second port P22 is Ftc, the output pressure is based on

Fsol+Fspg＞Ftc，

The spool 62 of the shift valve V2 may stroke to a position blocking the fifth port P25. Thus, the oil discharged from the sub-pump PS merges with the oil discharged from the main pump PM via the check valve V8 of the third oil passage L3. The merged oil is regulated to a line pressure by a regulator valve V1.

Fig. 5 is a hydraulic circuit diagram showing the flow of oil in the lubrication mode (when the initial pressure is sufficient). In the lubrication mode (when the initial pressure is sufficient), the solenoid valve V5 is opened. Also, the initial pressure of the torque converter TC is in a sufficient state (a state of being pressure-regulated via the TC regulator valve V6). In this state, the initial pressure of the torque converter TC applied to the spool 62 of the shift valve V2 via the fourth oil passage L4 and the second port P22 biases the spool 62 toward the left in fig. 5, thereby according to the pressure

Fspg＜Ftc，

The shift valve V2 communicates the fifth port P25 with the fourth port P24. Accordingly, the oil discharged from the sub-pump PS flows into the second oil passage L2 and is supplied to the lubrication system 103. At this time, the spool 42 of the shift prevention valve V4 is urged by the spring 41 to hit the right and the first port P41 and the second port P42 are communicated with each other, but the hydraulic pressure supplied from the first port P41 through the eighth oil passage L8 does not act on the shift valve V2.

Fig. 6 is a hydraulic circuit diagram showing the flow of oil in the lubrication mode (when the initial pressure is lowered). In the lubrication mode (when the initial pressure drops), the solenoid valve V5 is turned off. Then, the initial pressure of the torque converter TC is in a state of starting to fall. Even if the initial pressure of the torque converter TC starts to drop, the valve body 62 of the shift valve V2 moves to the right in fig. 6 until it reaches a position expressed by the following equation,

Fspg＝Ftc。

at this time, the step portion 62b of the valve body 62 of the shift valve V2 is in a stage of being short of the first port P21. Therefore, the hydraulic pressure supplied from the first port P41 through the eighth oil passage L8 still does not act on the shift valve V2.

Fig. 7 is a hydraulic circuit diagram showing the flow of oil in the high-pressure mode (automatic). In the high-pressure mode (automatic), the solenoid valve V5 is turned off. Also, the initial pressure of the torque converter TC may be either a rich state or a droop state. In this state, the initial pressure of the torque converter TC becomes equal to or lower than the predetermined pressure, and the hydraulic pressure supplied from the eighth oil passage L8 to the first port P21 is applied to the step portion 62b by the step portion 62b of the valve body 62 approaching the first port P21 of the shift valve V2. If the oil pressure applied to the step portion 62b is Fpi, then

Fspg+Fpi＞Ftc，

The spool 62 of the shift valve V2 thus moves to the right end, blocking the fifth port P25. Therefore, the oil discharged from the sub-pump PS merges with the oil discharged from the main pump PM via the check valve V8 of the third oil passage L3. The merged oil is regulated to a line pressure by a regulator valve V1. Thus, the line pressure is sufficient, the initial pressure of the torque converter TC is restored, but the oil pressure Fpi applied to the step portion 62b does not return to zero. Therefore, the spool 62 of the shift valve V2 does not move from the right end. Thus, even if the solenoid valve V5 is turned off and the internal pressure of the torque converter TC is sufficient, the shift does not occur in the lubrication mode. That is, the setting of the biasing force of the spring 61 of the shift valve V2 and the application of the hydraulic pressure supplied from the eighth oil passage L8 via the first port P21 to the step portion 62b of the spool 62 do not automatically switch to the lubrication mode once the high-pressure mode is established.

As described above, when the high-pressure mode is set by the automatic switching, even if the initial pressure of the torque converter TC is restored, the load (Fpi) due to the hydraulic pressure applied to the step portion 62b of the spool 62 remains, and the mode does not shift to the lubrication mode as instructed by the solenoid valve V5 only by the load (Fpi). That is, the hydraulic circuit 100 of the present embodiment includes the following means: even if the mode is automatically switched to the high-pressure mode, the mode returns to the lubrication mode again only when it is determined that the mode is the high-pressure mode → the lubrication mode based on the balance calculation. Therefore, the oscillation in which the high-pressure mode and the lubrication mode are frequently switched can be avoided.

Fig. 8(a) to 8(c) are views for explaining a procedure of switching from the high-pressure mode (automatic) to the lubrication mode. In the high-pressure mode (automatic) shown in FIG. 8(a), according to

Fspg+Fpi＞Ftc，

The spool 62 of the shift valve V2 is in the high pressure mode position. Next, in the high-pressure mode (forced) shown in fig. 8(b), the solenoid valve V5 is turned on, and the hydraulic pressure is supplied to the third port P43 of the shift prevention valve V4. Thereby, the spool 42 of the shift prevention valve V4 returns to the left in fig. 8 (b). On the other hand, the valve spool 62 of the shift valve V2 remains stationary. To shift from the state to the lubrication mode shown in fig. 8(c), the spool 62 of the shift valve V2 is moved to the left in fig. 8(c) to communicate the fifth port P25 of the shift valve V2 with the fourth port P24 by the solenoid valve V5 becoming open and the initial pressure of the torque converter TC (internal pressure in a sufficient state) being supplied to the second port P22 of the shift valve V2. Then, the valve spool 42 of the shift prevention valve V4 is moved to the right in fig. 8(c) to communicate the second port P42 with the first port P41.

Here, in fig. 8(c), in order to prevent the step portion 62b of the valve body 62 of the shift valve V2 from being exposed to the second port P22 and then move the valve body 42 of the shift prevention valve V4 so as to communicate the second port P42 with the first port P41, a restriction (not shown) must be provided in an oil passage communicating with the fourth port P44 of the shift prevention valve V4. Thus, the switching timing of the shift valve V2 and the shift block valve V4 is adjusted to the order of the shift valve V2 → the shift block valve V4.

Fig. 9 is a diagram for explaining switching of the high-pressure mode (forced), the high-pressure mode (automatic), and the lubrication mode of the hydraulic circuit 100. As shown in fig. 9, in the lubrication mode 201, the solenoid valve V5 is turned on (high-pressure mode command), and the mode is switched to the high-pressure mode (forced) 202 (path 211). When the initial pressure of the torque converter TC is made sufficient in the high-pressure mode (forced) 202, the solenoid valve V5 is turned off (lubrication mode command) (path 212), and the lubrication mode 201 is established.

When the initial pressure of the torque converter TC decreases (becomes insufficient) in the lubrication mode 201, the solenoid valve V5 is turned off (lubrication mode command), and the lubrication mode 201 is automatically switched to the high-pressure mode (automatic) 203 (path 213). On the other hand, in the high-pressure mode (automatic), when the initial pressure of the torque converter TC is restored (to the predetermined pressure again after being lower than the predetermined pressure at which the automatic switching is performed), the state of the high-pressure mode (automatic) is maintained (the circuit of the path 214 is not returned to the lubrication mode 201) by turning off the solenoid valve V5 (lubrication mode command). On the other hand, in the high-pressure mode (automatic) 203, the solenoid valve V5 is turned on (high-pressure mode command) (path 215), and the mode is switched to the high-pressure mode (forced) 202.

That is, when the high-pressure mode (automatic) 203 is once set, the solenoid valve V5 is turned on (high-pressure mode command), and thus the lubrication mode is not automatically returned to the lubrication mode unless the high-pressure mode (forced) 202 is passed.

As described above, according to the hydraulic circuit 100 of the present embodiment, the first oil passage L1 and the second oil passage L2 communicate with each other via the shift valve V2, and the lubrication mode (low-pressure mode) in which the discharge pressure of the sub pump PS is supplied to the lubrication system 103 is set, while the first oil passage L1 and the second oil passage L2 do not communicate with each other, and the discharge pressure of the sub pump PS is increased, and the check valve V8 is opened, and the high-pressure mode in which the discharge pressure of the sub pump PS and the discharge pressure of the main pump PM are merged is set. The high-pressure mode and the low-pressure mode can be switched by switching the communication/non-communication between the first oil passage L1 and the second oil passage L2 switched by the shift valve V2 by turning on/off the solenoid valve V5, and the communication between the first oil passage L1 and the second oil passage L2 is cut off by setting the hydraulic pressure of the fourth oil passage L4 (the initial pressure of the torque converter TC) to a predetermined value or less, thereby (automatically) switching from the low-pressure mode to the high-pressure mode. This can effectively prevent the hydraulic circuit 100 from supplying insufficient hydraulic pressure to the control target including the gear shift control system 102 and the lubrication system 103.

On the other hand, after the high-pressure mode is once set, the high-pressure mode is returned to the low-pressure mode only by the solenoid valve V5 being turned off, and the hydraulic pressure in the fourth oil passage L4 is returned to a hydraulic pressure exceeding a predetermined value, so that the high-pressure mode and the low-pressure mode are not (automatically) returned to the low-pressure mode, and hunting phenomenon that frequently occurs when the high-pressure mode and the low-pressure mode are switched due to a variation in the hydraulic pressure in the fourth oil passage L4 can be. Therefore, it is possible to prevent the shortage of the oil pressure supplied to the control target and to avoid the hunting caused by the switching between the high-pressure mode and the low-pressure mode.

While the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various modifications are possible within the scope of the technical idea described in the specification and the drawings. For example, in the above embodiment, the case where the high-pressure oil supply destination of the present invention is the transmission control system 102 and the low-pressure oil supply destination is the lubrication system 103 has been described, but the high-pressure oil supply destination of the present invention may include other control targets such as the torque converter 19 in addition to the transmission control system 102. The low-pressure oil supply destination of the present invention may include another low-pressure oil supply destination other than the lubrication system 103.