JPH10141456A - Hydraulic control circuit for continuously variable transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the interference due to the fluctuation of pressure among pulley control pressure which is set by adjusting pressure of oil discharged from an oil pump and clutch control pressure and lubrication pressure which are set by adjusting its drain pressure. SOLUTION: In a clutch control pressure control valve 29 which sets clutch control pressure Pc by adjusting drain pressure of line pressure Ps which gives tensile force required for torque transmission to a secondary pulley 9c of a continuously variable transmission 9 by adjusting discharge pressure from an oil pump 21, clutch control pressure Pc is adjusted for line pressure Ps in such a manner that a difference in pressure becomes substantially 1.5kgf/cm<2> and in a lubrication pressure control valve 50 which sets lubrication pressure PL by adjusting drain pressure of clutch control pressure Pc, lubrication pressure PL is adjusted for clutch control pressure Pc in such a manner that a difference in pressure becomes substantially 1.5kgf/cm<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control circuit for a continuously variable transmission that reduces noise in a circuit such as a surge noise caused by pressure fluctuations in the circuit.

[0002]

2. Description of the Related Art Generally, a torque converter is used as a starting clutch, and a planetary gear type forward / backward switching device is employed as a forward / reverse switching device. In the continuously variable transmission provided with a lock-up clutch that outputs the torque to the continuously variable transmission without passing through the fluid of the torque converter, the hydraulic pressure discharged from the engine-driven oil pump causes the pulley control pressure of the continuously variable transmission to be reduced. Secure,
Further, the drainage pressure of the pulley control pressure is used to obtain the forward / reverse switching device, the clutch control pressure for the lock-up clutch, and the lubrication pressure to be supplied to the lubrication of the mechanical part.

[0003] The discharge flow rate of an engine-driven oil pump is often set based on the maximum required flow rate during the shift control of the continuously variable transmission. That is,
There is a case where a large amount of oil is required when performing the speed change control of the continuously variable transmission, and the capacity of the oil pump is set corresponding to this state. Also, the discharge flow rate of the oil pump when the continuously variable transmission is not performing the shifting operation may be small because the required amount of lubricating oil of the transmission itself at this time is also small, and therefore, when considering the mechanical efficiency, It is desirable that the pump capacity of the engine-driven oil pump satisfy the above-mentioned maximum required flow rate and be set as small as possible.

However, when the pump displacement is set on the basis of the maximum required shift speed of the continuously variable transmission under normal operating conditions, the shift control of the continuously variable transmission is performed under special running conditions such as sudden braking. It may be difficult to secure a sufficient amount of oil to perform. In other words, when a heavy load is applied to the engine by an operation such as sudden braking during traveling, the engine speed decreases and the discharge flow rate of the engine-driven oil pump decreases, so that the pulley control supplied to the continuously variable transmission is controlled. The pressure drops, which hinders the shift control of the continuously variable transmission.

Further, when the discharge flow rate of the oil pump decreases, the drain flow rate from the pulley control pressure decreases,
When the drain flow rate decreases, for example, when the clutch control pressure and the lubrication pressure are adjusted using the drain pressure of the pulley control pressure, at least the clutch control pressure decreases. Can be considered. As a result, various clutches, solenoid valves, and the like that use the clutch control pressure as the operating pressure do not operate normally, causing clutch slippage, poor valve operation, and the like, which hinders normal shift control.

When the discharge flow rate of an engine-driven oil pump is set based on the maximum required shift speed of a continuously variable transmission, the discharge rate of the oil pump is low when the engine speed is low, such as in idle operation. In some cases, a sufficient flow rate cannot be obtained, resulting in insufficient supply of hydraulic oil. For example, when shifting from the neutral to the D range and shifting to the forward running state, a clutch control pressure is supplied to the forward / reverse switching device, and the forward clutch is engaged to rotate the forward / backward switching device integrally. In addition, the required flow rate of the hydraulic oil instantaneously increases, resulting in a temporary shortage of the flow rate, which may cause an operation delay or an operation failure.

As a countermeasure, for example, Japanese Patent Laid-Open No. 4-35
No. 7357 discloses that by separating a hydraulic oil passage that circulates a clutch control pressure and a hydraulic oil passage that circulates a lubricating pressure, and adjusting the drain pressure of the clutch control pressure to set the lubricating pressure,
Technology that can secure the minimum necessary flow and pressure for the clutch control pressure even if the discharge flow rate of the engine-driven oil pump decreases under specific operating conditions and the flow rate temporarily becomes insufficient. Is disclosed.

[0008]

However, as shown in FIG. 7, the pulley control pressure, the clutch control pressure, and the lubrication pressure for the continuously variable transmission are affected by the pulsation of the oil pump or the turbulence of the flow. , A pressure fluctuation Pd having a substantially constant width (for example, 0.3 Kgf / cm ² at the lubricating pressure) is generated, and the pulley control pressure and the clutch control pressure, and the clutch control pressure and the lubricating pressure are set to close pressures. In such a case, not only the operating noise in the oil passage such as a surge noise is likely to be generated due to the mutual interference, but also the pressure fluctuation width is amplified, which may interfere with the hydraulic control in the circuit.

Now, the required characteristics of the pulley control pressure and the clutch control pressure will be described. The pulley control pressure is the holding pressure (secondary pressure) of the belt of the continuously variable transmission.
And the shift control pressure (primary pressure), the friction loss between the belt and the pulley, and the pump driving force for obtaining the predetermined pulley control pressure are power losses and affect fuel efficiency. When the pressure is low, the pulley control pressure also needs to be reduced.

However, when a torque converter is employed as the starting clutch, the torque ratio ts becomes maximum at the stall point, which is the stop point of the engine output shaft, and becomes minimum (ts = 1.0) when the lock-up clutch is engaged. For,
The pulley control pressure must ensure a pressure that does not cause the belt to slip even in the state of the maximum torque ratio at the stall point. Therefore, a wide range of pressure setting from high pressure to low pressure according to the torque ratio ts is required. Is required.

On the other hand, the clutch control pressure needs to be set high when the driving force is large. As means for securing the coupling force of the clutch, it is conceivable to increase the number of clutches in addition to increasing the clutch control pressure. However, in this technique, it is possible to secure the coupling force while keeping the clutch control pressure low, but increasing the number of clutches increases the cost and secures a sufficient space for accommodating the clutch. It is difficult.
In this regard, in the technique of setting the clutch control pressure according to the driving force, for example, when a lock-up mechanism is provided with the torque converter, the minimum torque ratio is obtained when the lock-up clutch is engaged, and the clutch The required pressure can be kept low.

In consideration of the above-described required characteristics of the pulley control pressure and the clutch control pressure, when the pulley pressure of the continuously variable transmission is reduced to reduce the mechanical loss during lock-up engagement, the clutch control pressure is reduced. Maintaining a high pressure in consideration of the maximum torque ratio at the stall point is performed by adjusting the pulley control pressure, the clutch control pressure set by adjusting the drain pressure of the pulley control pressure, and the drain pressure of the clutch control pressure. The pressure between the pressure and the set lubrication pressure may be close to each other, which may cause noise in the circuit such as the above-described surge noise.

Conventionally, as means for reducing the noise in the circuit such as the surge noise, measures such as interposing an accumulator in the circuit and changing the material of the control valve have been taken, but the accumulator is housed. Not only is it difficult to secure space, but there are problems such as increased costs.
Similarly, reducing the noise in the circuit by adding a solenoid or the like in the circuit requires an additional control system, which results in a significant increase in cost and is not feasible.

The present invention has been made in view of the above circumstances, and has as its object to provide a hydraulic control circuit of a continuously variable transmission capable of reducing noise in a circuit with a simple configuration without increasing costs. .

[0015]

In order to achieve the above object, a hydraulic control circuit of a first continuously variable transmission according to the present invention comprises a starting clutch having a lock-up clutch, a forward / reverse switching device, and a continuously variable transmission in a drive system. A first pressure that adjusts a discharge pressure from an engine-driven oil pump to set a pulley control pressure for the continuously variable transmission low when the lock-up clutch is engaged and high when the lock-up clutch is released. A control valve, a second pressure control valve for adjusting a drain pressure of the pulley control pressure to set a clutch control pressure for an apply side of a lock-up clutch provided on the starting clutch and an operation clutch of the forward / reverse switching device. Adjusting the drain pressure of the clutch control pressure to set the lubricating pressure to be supplied to the release side of the lock-up clutch and the lubrication required portion. And a pressure difference between the pulley pressure and the clutch control pressure and a pressure difference between the clutch control pressure and the lubrication pressure are set to values that do not interfere with each other. A pressure control working chamber provided in the second pressure control valve and the third pressure control valve and a lock-up working chamber provided in a lock-up control valve for shutting off the supply of the clutch control pressure to the lock-up clutch. The first hydraulic circuit communicates via a first hydraulic circuit, and the first hydraulic circuit and a second hydraulic circuit which circulates the clutch control pressure are disconnected when the lock-up clutch is connected and disconnected when the lock-up clutch is released. It is characterized in that the first hydraulic circuit can be freely communicated via flow passage switching means for leading to the drain oil passage.

In order to achieve the above object, the second aspect of the present invention
The hydraulic control circuit of the continuously variable transmission according to the first aspect is characterized in that, in the hydraulic control circuit of the first continuously variable transmission, the pressure difference is 1.5 kgf / cm ² or more.

In order to achieve the above object, a third aspect of the present invention is provided.
The hydraulic control circuit of the continuously variable transmission according to the first aspect of the present invention is the hydraulic control circuit of the first continuously variable transmission, wherein the hydraulic control circuit of the first continuously variable transmission is provided between the flow path switching unit of the first hydraulic circuit and the lockup control valve. A check valve allowing flow from the switching means to the lock-up control valve and a throttle oil passage are interposed in parallel.
Between the second pressure control valve and the third pressure control valve and the second pressure control valve between the second pressure control valve and the third pressure control valve. It is characterized in that a check valve allowing flow and a throttle oil passage are interposed in parallel.

According to the fourth aspect of the present invention, there is provided
The hydraulic control circuit of the continuously variable transmission is a hydraulic control circuit of the first continuously variable transmission, wherein the hydraulic control circuit of the first continuously variable transmission is provided between the flow path switching unit of the first hydraulic circuit and the second pressure control valve. A check valve permitting the flow from the second pressure control valve to the first hydraulic circuit and a throttle oil path are interposed in parallel, and further, the flow path switching means of the first hydraulic circuit and the third A check valve which permits flow from the flow path switching means to the third pressure control valve and a throttle oil passage are interposed between the pressure control valve and the third pressure control valve.

According to the fifth aspect of the present invention, there is provided the above-mentioned object.
The hydraulic control circuit of the continuously variable transmission according to the first aspect of the present invention is the hydraulic control circuit of the first continuously variable transmission, wherein the hydraulic control circuit of the first continuously variable transmission includes the flow path between the flow path switching unit of the first hydraulic circuit and the lock-up control valve. A check valve allowing flow from the switching means to the lock-up control valve and a throttle oil passage are interposed in parallel.
A check valve and a throttle oil passage that allow flow from the second pressure control valve to the flow path switching means are arranged in parallel between the flow path switching means and the second pressure control valve of the hydraulic circuit. A check valve interposed between the flow passage switching means of the first hydraulic circuit and the third pressure control valve to allow flow from the flow passage switching means to the third pressure control valve. The valve and the throttle oil passage are interposed.

In the hydraulic control circuit of the first continuously variable transmission,
The discharge pressure from the engine-driven oil pump is adjusted by the first pressure control valve in accordance with the state of the lock-up clutch provided on the starting clutch to set the pulley control pressure for the continuously variable transmission, A drain pressure of the pulley control pressure is adjusted by a pressure control valve to set a clutch control pressure for the apply side of the lock-up clutch and an operation clutch of the forward / reverse switching device, and thereafter, the drain pressure of the clutch control pressure is reduced to a second pressure. In setting the lubricating pressure to be supplied to the release side of the lock-up clutch and the lubrication required by adjusting the pressure by the pressure control valve of No. 3, the pulley pressure is controlled by the first pressure control valve and the second pressure control valve. The pressure difference between the clutch control pressure and the clutch control pressure is set to a value that does not interfere with each other, and the clutch is controlled by the second pressure control valve and the third pressure control valve. The pressure difference between the switch control pressure and the lubricating pressure is set to a value that does not interfere with each other. When the lock-up clutch is engaged, the flow path switching means connects the second hydraulic circuit that circulates the clutch control pressure to the first hydraulic circuit, and the clutch control pressure is used as the original pressure. The operating pressure flows into the first hydraulic circuit. Then, the operating pressure is supplied to a lock-up operation chamber provided in a lock-up control valve that shuts off the supply of the clutch control pressure to the lock-up clutch, and the second pressure control valve and the third pressure control valve Are supplied to the pressure control working chambers respectively provided for the pressure control and the pressure control. As a result, the second pressure control valve lowers the clutch control pressure, the third pressure control valve lowers the lubrication pressure, and the clutch control pressure is reduced via the lock-up control valve. Supplied to the lock-up clutch, the lock-up clutch is engaged. On the other hand, when the lock-up clutch is released, the second flow path through which the clutch control pressure flows by the flow path switching means is used.
And shut off the first hydraulic circuit and
The first hydraulic circuit is guided to a drain oil passage. Then, the operating pressures supplied to the lock-up operation chamber provided in the lock-up control valve and the pressure control operation chambers provided in the second pressure control valve and the third pressure control valve, respectively, are drained. Then, the lock-up clutch is released, and the second pressure control valve and the third pressure control valve increase both the clutch control pressure and the lubrication pressure.

In the hydraulic control circuit of the second continuously variable transmission,
In the hydraulic control circuit of the first continuously variable transmission, the pressure difference is at least 1.5 kgf / c as a value for avoiding mutual interference.
and m ^2.

In the hydraulic control circuit of the third continuously variable transmission,
In the hydraulic control circuit for a first continuously variable transmission,
A check valve and a throttle oil passage which allow flow from the flow path switching means to the lock-up control valve are interposed between the flow path switching means and the lock-up control valve of the hydraulic circuit in parallel. Further, between the flow path switching means of the first hydraulic circuit and the second pressure control valve and the third pressure control valve, the second pressure control valve and the third pressure control valve By interposing a check valve and a throttle oil path in parallel to allow flow to the flow path switching means, when coupling the lock-up clutch,
When the second hydraulic circuit that circulates the clutch control pressure is communicated with the first hydraulic circuit by the flow path switching unit, the operating pressure that uses the clutch control pressure that circulates through the second hydraulic circuit as the original pressure becomes the second pressure. And the operating pressure is supplied to a lock-up operation chamber provided in the lock-up control valve via a check valve, and the operating pressure of the second pressure control valve and the third pressure control valve is increased. It is supplied to the working chamber via a throttle oil passage.
As a result, the clutch control pressure and the lubrication pressure are reduced after the lock-up clutch is engaged. On the other hand, when the lock-up clutch is released,
Of the first hydraulic circuit and the first hydraulic circuit,
Of the hydraulic circuit to the drain oil passage. Then, the operating pressure supplied to the lock-up operation chamber provided in the lock-up control valve is drained through the throttle oil passage, and the operation chambers of the second pressure control valve and the third pressure control valve are operated. The working pressure supplied to the valve is drained through a check valve. As a result, the lock-up clutch is released after the clutch control pressure and the lubrication pressure increase.

In the hydraulic control circuit of the fourth continuously variable transmission,
In the hydraulic control circuit for a first continuously variable transmission,
A check valve and a throttle oil passage which allow flow from the second pressure control valve to the first hydraulic circuit are arranged in parallel between the flow path switching means of the hydraulic circuit and the second pressure control valve. A check valve interposed between the flow path switching means of the first hydraulic circuit and the third pressure control valve to allow flow from the flow path switching means to the third pressure control valve. When the lock-up clutch is connected by interposing the valve and the throttle oil passage, the second hydraulic circuit and the first hydraulic circuit are communicated by the path switching means, and the second hydraulic circuit is circulated. An operating pressure based on the clutch control pressure to be applied is supplied to the first hydraulic circuit. Then, the operating pressure is supplied to a lock-up operation chamber provided in the lock-up control valve, and is supplied to the second pressure control valve via a throttle oil passage, and the third pressure control valve is operated. The chamber is supplied via a check valve. as a result,
When the lock-up clutch is engaged, the lubricating pressure first decreases, and then the clutch control pressure decreases. On the other hand, when releasing the lock-up clutch, the second hydraulic circuit and the first hydraulic circuit are cut off by the flow path switching means, and the first hydraulic circuit is guided to the drain oil path. Then, the operating pressure supplied to the lock-up operating chamber provided in the lock-up control valve is drained, and the operating pressure supplied to the operating chamber of the second pressure control valve is transmitted through the check valve. The working pressure supplied to the working chamber of the third pressure control valve is drained through the throttle oil passage. As a result, when the lockup is released, first, the clutch control pressure increases, and then the lubrication pressure increases.

In the hydraulic control circuit of the fifth continuously variable transmission,
In the hydraulic control circuit for a first continuously variable transmission,
A check valve and a throttle oil passage which allow flow from the flow path switching means to the lock-up control valve are interposed between the flow path switching means and the lock-up control valve of the hydraulic circuit in parallel. A check valve that allows a flow from the second pressure control valve to the flow path switching means between the flow path switching means of the first hydraulic circuit and the second pressure control valve; A throttle oil passage interposed in parallel, and between the passage switching means and the third pressure control valve of the first hydraulic circuit, the passage from the passage switching means to the third pressure control valve. The second hydraulic circuit and the first hydraulic circuit are communicated by the flow path switching means when the lock-up clutch is engaged by interposing the check valve and the throttle oil passage that allow the flow. Thus, when an operating pressure based on the clutch control pressure of the first hydraulic circuit as a base pressure is supplied, the operating pressure It is supplied through a check valve to the lock-up operating chamber provided in the lock-up control valve, and a second
Is supplied through a throttle oil passage to the pressure control valve of
Is supplied to the working chamber of the pressure control valve through a check valve. As a result, first, the lock-up clutch is engaged, and the lubrication pressure is reduced, and then the clutch control pressure is reduced. on the other hand,
When releasing the lock-up clutch, the second hydraulic circuit and the first hydraulic circuit are cut off by the flow path switching means, and the first hydraulic circuit is guided to a drain oil passage. Then, the operating pressure supplied to the lock-up operating chamber provided in the lock-up control valve is drained by forming a throttle oil passage, and the operating pressure supplied to the operating chamber of the second pressure control valve is increased. Is drained via a check valve, and the working pressure supplied to the working chamber of the third pressure control valve is drained via a throttle oil passage. As a result, first, the clutch control pressure increases, then the lock-up clutch is released, and the lubrication pressure increases.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 show a first embodiment of the present invention.

In FIG. 4, reference numeral 1 denotes an engine. An output shaft 2 of the engine 1 is connected to a drive shaft 6 supporting a drive wheel 5 via a continuously variable transmission 3 and a final reduction gear 4. The continuously variable transmission 3 includes a torque converter 7 as an example of a starting clutch, a planetary gear type forward / reverse switching device 8 and a continuously variable transmission 9 from the input side.

An output shaft 2 of the engine 1 is connected to an impeller 7a of the torque converter 7, and a turbine 7b of the torque converter 7 is connected to an input shaft 8a of the forward / reverse switching device 8. The torque converter 7 is provided with a lock-up clutch 7c.
When the lock-up clutch 7c is engaged, the output shaft 2 of the engine 1 and the turbine 7b are directly connected without any fluid.

The forward / reverse switching device 8 includes a double pinion type planetary gear 10, and the input shaft 8 a is connected to a sun gear 10 a of the planetary gear 10.
Further, the sun gear 10a and the carrier 10b can be freely disengaged via a forward clutch 11, and the ring gear 10c and the transmission case 3a can be freely disengaged via a reverse brake 12.

When the forward clutch 11 is engaged, the planetary gear 10 rotates integrally, and when the reverse brake 12 is engaged, reverse power is transmitted to the input shaft 9a of the continuously variable transmission 9. In a state where both the forward clutch 11 and the reverse brake 12 are released, the planetary gear 10 is in a neutral state, and the transmission of power in the drive system is cut off.

A primary pulley 9b is mounted on an input shaft 9a of the continuously variable transmission 9 connected to the carrier 10b of the forward / reverse switching device 8, and a secondary pulley 9c provided opposite the primary pulley 9b is connected to an output shaft 9d. The two pulleys 9b and 9c are connected via a belt 9e. A primary hydraulic chamber 9f and a secondary hydraulic chamber 9g are provided on the movable sheave side of each of the pulleys 9b and 9c, and the working pressure supplied to each of the hydraulic chambers 9f and 9g causes the groove width of the pulleys 9b and 9c to be increased. Is set to the inverse proportional state to perform the shift control. Also, the output shaft 9 of the continuously variable transmission 9
d is connected to a differential device 4b which is mounted on the drive shaft 6 via a reduction gear group 4a of the final reduction device 4.

Next, a hydraulic control circuit for supplying operating hydraulic pressure to the lock-up clutch 7c, the forward clutch 11, the reverse brake 12, and the hydraulic chambers 9f and 9g of the continuously variable transmission 9 will be described.

Reference numeral 21 in FIG. 1 denotes an engine-driven oil pump, which includes a main pump 21a and a sub-pump 21b, and the suction ports of both pumps 21a and 21b are connected to an oil pan 22. The discharge port of the main pump 21a is directly connected to the line pressure circuit 23, while the discharge port of the sub-pump 21b is connected to the line pressure circuit 23 via the switching valve 24. The switching valve 24 performs a switching operation by a control pressure supplied from a switching solenoid valve 25, and the switching solenoid valve 25 is controlled and operated based on a control signal from a control unit 26 (see FIG. 3).

For example, when the pump flow rate is relatively large, such as in a steady operation at a high speed, the switching valve 24 is closed via the switching solenoid valve 25, and the line pressure circuit 2 is closed.
3, the hydraulic pressure is supplied only from the main pump 21a. On the other hand, when the required flow rate is relatively large, such as during start-up acceleration, the switching valve 24 is opened, and hydraulic pressure is supplied to the line pressure circuit 23 from both the main pump 21a and the sub-pump 21b.

The discharge pressure from the oil pump 21 supplied to the line pressure circuit 23 is controlled by a line pressure control valve 27b provided alongside a primary pressure control valve 27a of a hydraulic control device 27 as a first pressure control valve. Relatively high line pressure P
s, and the adjusted line pressure Ps is applied to the secondary hydraulic chamber 9g of the secondary pulley 9c of the continuously variable transmission 9,
It is supplied to the primary pressure control valve 27a and the like. The primary pressure control valve 27a reduces the line pressure Ps and supplies a primary pressure Pp (Pp <P) to a primary hydraulic chamber 9f provided in a primary pulley 9b of the continuously variable transmission 9.
s).

The line pressure Ps and the primary pressure Pp
Is set by the control unit 26 (see FIG. 3). In the control unit 26, when the lock-up clutch 7c attached to the torque converter 7 is in the engaged state, the torque converter has a minimum value of the torque ratio ts = 1.0,
Since the engine torque is transmitted without being amplified, the fuel efficiency is improved by controlling the line pressure Ps and the primary pressure Pp within a relatively low pressure range. On the other hand, when the lock-up clutch 7c is released, the torque ratio ts
Is increased, and a large torque is transmitted to the belt. Therefore, the two pressures Ps and Pp are controlled in a high pressure range in consideration of the maximum torque ratio at which a stall occurs.

As shown in FIG. 3, the hydraulic control device 27
The control valves 27a and 27b provided in the control unit 2
Pressure control solenoid valve 27c and line pressure control solenoid valve 2 that operate in accordance with the control signal from control line 6
The primary pressure Pp and the line pressure Ps are set according to the operation amount of 7d. In the continuously variable transmission 9, the transmission control is performed by maintaining the tension of the belt 9e by the line pressure Ps supplied to the secondary pulley 9c and variably setting the groove width of the primary pulley 9b by the primary pressure Pp. Do.

A clutch control pressure oil passage 28, which is a first hydraulic circuit, is connected to a drain port of the line pressure control valve 27b of the hydraulic control device 27. The hydraulic pressure supplied from the line pressure control valve 27b to the clutch control pressure oil passage 28 is adjusted to a predetermined clutch control pressure Pc by a clutch control pressure control valve 29 which is a second pressure control valve.

The clutch control pressure oil passage 28 and the line pressure circuit 23 are connected to a forward clutch oil passage 32 communicating with the forward clutch 11 via a safety lock valve 30 and a manual valve 31 interlocked with a select lever (not shown). A reverse brake oil passage 33 communicating with the reverse brake 12 is freely communicable.

Further, the safety lock valve 30 may cause the select lever to be erroneously selected to the R range while the vehicle is traveling forward, or may be used for sudden braking or locking of tires associated therewith.
When a sudden rotation fluctuation exceeding the permissible shift speed of the continuously variable transmission 9 is transmitted from the drive wheels 5 to the continuously variable transmission 9, the rotation is supplied to the forward clutch 11 and the reverse brake 12. By immediately draining the operating pressure, the forward / reverse switching device 8 is forcibly brought into the neutral state. The switching operation of the safety lock valve 30 is performed by the operation chamber of the safety lock valve 30 and the clutch control hydraulic oil. The control is performed by a safety lock solenoid valve 34 interposed in a control pressure oil passage 34 a communicating with the passage 28.

The safety lock solenoid valve 34 is normally in a closed state. Therefore, the working chamber of the safety lock valve 30 has an operating hydraulic pressure based on the clutch control pressure Pc flowing through the clutch control pressure oil passage 28 as a base pressure. Is not supplied, and the forward clutch oil passage 32 and the reverse brake oil passage 33 are maintained in a freely circulating state. An ON signal to the safety lock solenoid valve 34 is output from the control unit 26, and when an ON signal is output to the safety lock solenoid valve 34, the clutch control is performed from the safety lock solenoid valve 34 to the working chamber of the safety lock valve 30. An operating oil pressure based on the pressure Pc is supplied, and the safety lock valve 30 is connected to a forward clutch oil passage 32 communicating with the forward clutch 11 side and the reverse brake 12 side.
And the reverse brake oil passage 33 are connected to a drain port 33a opened at the center of the safety lock valve 30, and both the forward clutch 11 and the reverse brake 12 are released.

When the selector lever interlocking with the manual valve 31 is selected to the neutral (N) range or the parking (P) range, the manual valve 31 moves the forward clutch oil passage 32 and the reverse brake oil passage 33. Drains both the line pressure Ps and the clutch control pressure Pc flowing into the clutch control pressure oil passage 2 when the drive (D) range is selected.
8 in communication with the forward clutch oil passage 32 and the line pressure Ps flowing into the reverse brake oil passage 33.
Drain. On the other hand, when the reverse (R) range is selected, the line pressure circuit 23 is connected to the reverse brake oil passage 33 and the clutch control pressure Pc flowing into the clutch control pressure oil passage 28 is drained.

The orifice 35, the forward clutch 11, and the reverse brake 12 provide the safety lock valve 30 downstream of the manual valve 31 in the forward clutch oil passage 32 and the reverse brake oil passage 33.
And a check valve 36 that allows only the flow through the check valve 36 is interposed in parallel.

Further, a fluctuation in the operating pressure supplied to the forward clutch 11 and the reverse brake 12 is buffered immediately upstream of the forward clutch 11 and the reverse brake 12 in the forward clutch oil passage 32 and the reverse brake oil passage 33. Accumulators 37 and 38 are connected.

Reference numeral 40 denotes a lock-up control valve for controlling engagement and disengagement of a lock-up clutch 7c provided in the torque converter 7, and the clutch control pressure oil passage 28 is provided on the inflow side of the lock-up control valve 40. And a release-side lubricating oil passage 41 communicating with a drain port of the clutch control pressure control valve 29, and an apply pressure oil passage 42 communicating with the apply side of the lock-up clutch 7c on the discharge side and a release-side lubricating oil passage 42. Is connected to a release pressure oil passage 43 communicating with the release pressure oil passage 43. The above-mentioned apply pressure oil passage 42
Is connected to a relief valve 44.

Further, a working pressure oil passage 45, which is a second hydraulic circuit, is connected to the working chamber of the lock-up control valve 40,
Further, a bias spring is interposed in a bias chamber of the lock-up control valve 40 which is disposed opposite to the working chamber, and a clutch control pressure oil passage 28 is connected to the bias chamber.

The working pressure oil passage 45 communicates with the working chambers of the clutch control pressure control valve 29 and the lubricating pressure control valve 50 as a third pressure control valve. The clutch control pressure oil passage 28 can be freely communicated with the oil passage 45 via a lock-up control solenoid valve 46 which is an example of a passage switching means in the middle of the oil passage 45.

The drain port of the clutch control pressure control valve 29 is provided with the release-side lubricating pressure oil passage 41 and a lubricating oil passage 49 for guiding lubricating oil to each lubricating part such as a mechanism of the continuously variable transmission 3. The lubricating pressure PL flowing through the release-side lubricating oil passage 41 and the lubricating oil passage 49 is regulated by the lubricating pressure control valve 50. Further, a drain port of the lubrication pressure control valve 50 is connected to the suction side of the oil pump 21.

As shown in FIG. 2, the lock-up control solenoid valve 46 has an inflow port 46a communicating with the clutch control pressure oil passage 28 and the operating pressure oil passage 45.
And a drain port 46c communicating with the drain oil passage 51 is opened, and a built-in valve body 46d connects the supply port 46b to the inflow port 46a in accordance with a control signal from the control unit 26.
And the drain port 46c.

That is, at the time of lock-up engagement, the clutch control pressure oil passage 28 communicates with the working pressure oil passage 45 (the state of FIG. 2), and the clutch control pressure Pc flowing through the clutch control pressure oil passage 28 is set to the original pressure. Is supplied to the working pressure oil passage 45, and when the lock-up is released, the clutch control pressure oil passage 28 and the working pressure oil passage 45 are cut off, and the working pressure oil passage 45 is connected to the drain oil passage 45. Lead to 51.

Also, between the lock-up control valve 40 and the supply port 46b of the lock-up control solenoid valve 46 of the operating pressure oil passage 45, the lock-up control valve is A check valve 52a allowing flow to 40 and a throttle oil passage 52b interposed with an orifice are interposed in parallel.

Further, the clutch control pressure control valve 29 is provided between the supply port 46b of the lock-up control solenoid valve 46 of the working pressure oil passage 45 and the clutch control pressure control valve 29 and the lubrication pressure control valve 50. And lubrication pressure control valve 50
A check valve 53a which permits the flow to the lock-up control solenoid valve 46 and a throttle oil passage 53b through which an orifice is interposed are arranged in parallel.

The lock-up control valve 40 is switched by the differential pressure between the operating pressure Po supplied to the working chamber, the clutch control pressure Pc flowing into the biasing chamber provided at the opposite end thereof, and the bias spring. You. That is, when the operating pressure PO supplied to the working chamber rises and becomes higher than the biasing force due to the cooperation between the clutch control pressure Pc flowing into the bias chamber provided at the opposite end thereof and the bias spring, the differential pressure causes Sliding connects the clutch control pressure oil passage 28 to the apply pressure oil passage 42 to supply an apply pressure PA having the clutch control pressure Pc as a base pressure to the apply side of the lock-up clutch 7c, and a release pressure oil passage. 43 is connected to the drain port to discharge the release pressure PR,
The lock-up clutch 7c is engaged. The release-side lubricating pressure oil passage 41 communicates with an oil passage 47 and is drained through an oil cooler 48.

On the other hand, the working pressure PO supplied to the working chamber of the lock-up control valve 40 is attenuated, and the lubricating pressure PL flowing into the bias chamber opposed to the working chamber and the bias spring are applied. When the pressure becomes lower than the force, the flow path is switched, and as shown in FIG. 1, the release-side lubrication pressure oil path 41 is connected to the release pressure oil path 43, and the lubrication pressure PL is applied to the release side of the lockup clutch 7c. The supply pressure PR is supplied to the supply side, and the apply pressure oil passage 42 is communicated with the drain oil passage 47 to discharge the apply pressure PAP supplied to the apply side, thereby releasing the lock-up clutch 7c.

The clutch control pressure control valve 29 and the lubrication pressure control valve 50 are connected to the working pressure P supplied to the working chamber.
The drain flow rate is variably set by balancing the force between O and a bias spring interposed in a bias chamber provided at the opposite end of the working chamber. That is, when the force by the operating pressure PO supplied to the working chambers of the control valves 29 and 50 becomes higher than the biasing force of the bias spring provided at the opposite end thereof,
Each of the control valves 29 and 50 slides against the biasing force of the bias spring to increase the drain flow rate of the lubricating oil. On the other hand, when the operating pressure PO supplied to the working chamber decreases and becomes lower than the biasing force of the bias spring, the control valves 29,
50 slides in the opposite direction under the biasing force of the bias spring, and reduces the drain flow rate of the lubricating oil. When the drain flow rates of the control valves 29 and 50 decrease, both the clutch control pressure Pc and the lubrication pressure PL flowing through the clutch control pressure oil passage 28 and the release-side lubrication pressure oil passage 41 increase,
When the drain flow rate of each of the control valves 29 and 50 increases, the clutch control pressure Pc and the lubrication pressure PL relatively decrease.

The line pressure Ps and the clutch control pressure P
c and the pressure difference Pd between the clutch control pressure Pc and the lubricating pressure PL are values that do not interfere with each other under the influence of pressure fluctuations due to pulsation of the oil pump 21, flow turbulence, and the like. In the form, it is set to at least 1.5 kgf / cm ² .

Next, the operation of the present embodiment will be described. The engine driven oil pump 21 is a main pump 2
1a and a sub-pump 22b. During operation of the engine, the main pump 21a constantly supplies the working oil stored in the oil pan 22 to the line pressure circuit 23, and the sub-pump 21b operates the switching valve 24 in accordance with the engine operating state. Hydraulic oil is supplied to the line pressure circuit 23 as needed. And
The hydraulic oil supplied to the line pressure circuit 23 is regulated by the line pressure control valve 27b of the hydraulic control device 27 to set a high line pressure Ps.

Then, the drain pressure from the line pressure control valve 27b flows into the clutch control pressure oil passage 28. The drain pressure from the line pressure control valve 27b flowing into the clutch control pressure oil passage 28 is regulated by the clutch control pressure control valve 29, and is set to a predetermined clutch control pressure Pc.

The drain pressure from the clutch control pressure control valve 29 flows into the release-side lubricating oil passage 41 and the lubricating oil passage 49 of the torque converter. Then, the drain pressure flowing into the release-side lubricating oil passage 41 and the lubricating oil passage 49 is adjusted by the lubricating pressure control valve 50 so that the lubricating pressure P
L, and the drain oil from the lubrication pressure control valve 50 is returned to the suction side of the oil pump 21.

The line pressure Ps flowing through the line pressure circuit 23, the clutch control pressure Pc flowing through the clutch control pressure oil passage 28, and the lubrication pressure PL flowing through the lubrication pressure oil passage 41 are determined by the line pressure control valve 27b and the clutch. Since the pressure difference Pd between the control pressures that are close to each other is set to at least 1.5 kgf / cm ² by the control pressure control valve 29 and the lubrication pressure control valve 50, the pressure due to the pulsation of the oil pump 21, the turbulence of the flow, etc. Even if affected by the fluctuation, they do not interfere with each other, so that it is possible to reduce noise in the circuit such as surge noise.

In the continuously variable transmission 9, the line pressure Ps is applied to a secondary hydraulic chamber 9g provided in the secondary pulley 9c.
Is supplied to the secondary pulley 9c to apply a tension required for torque transmission. On the other hand, the hydraulic control device 2 is provided in the primary hydraulic chamber 9f provided in the primary pulley 9b.
The primary pressure Pp regulated by the primary pressure control valve 27a of No. 7 is supplied, and the transmission control is performed by varying the groove width of the pulley with the primary pressure Pp.

When the primary pressure Pp and the line pressure Ps are set by the control unit 26 and the lock-up clutch 7c attached to the torque converter 7 is engaged, the torque ratio of the torque converter is 1.0.
The engine torque is transmitted to the continuously variable transmission as it is, and the line pressure Ps and the primary pressure Pp are controlled within a relatively low pressure range. On the other hand, the lock-up clutch 7c
Is released, the engine torque is increased in accordance with the slip ratio of the torque converter. Therefore, the two pressures Ps and Pp are controlled at a high pressure in consideration of the maximum torque ratio at the stall point. Therefore, the pressures Ps and Pp are controlled in a low range when the lock-up clutch 7c is in the engaged state, and in a high range when the lock-up clutch 7c is in the released state.

The engagement or disengagement of the lock-up clutch 7c is set by the control unit 26. When the lock-up clutch 7c is engaged, a control signal is output to a lock-up control solenoid valve 46, and the lock-up control solenoid is The valve body 46d of the valve 46 is operated to protrude,
The clutch control pressure oil passage 28 is communicated with the working pressure oil passage 45.

Then, an operating pressure PO based on the clutch control pressure Pc flowing through the clutch control pressure oil passage 28 flows into the operating pressure oil passage 45, and this operating pressure PO is used to operate the lock-up control valve 40. A bias spring which is quickly supplied to the chamber via a check valve 52a, is interposed in a bias chamber provided at an end opposite to the working chamber, and cooperates with a clutch control pressure Pc flowing into the bias chamber. The clutch control pressure oil passage 28 is connected to the apply pressure oil passage 42 and the release pressure oil passage 43
To the drain port, and further, the release-side lubricating pressure oil passage 41 to the drain oil passage 47.

As a result, the lock-up clutch 7c
Is supplied with the clutch control pressure Pc as the source pressure, the release pressure PR supplied to the release side is drained, and the lock-up clutch 7c is engaged.

At the same time, the working pressure PO flowing into the working pressure oil passage 45 flows into the respective working chambers of the clutch control pressure control valve 29 and the lubrication pressure control valve 50 via the throttle oil passage 53b having an orifice. The operating pressure PO flowing into each working chamber
However, the pressure is gradually increased due to the flow path resistance of the throttle oil passage 53b, and the operating pressure PO is eventually increased by the control valves 29,
When the biasing force is higher than the biasing force of the bias spring interposed in the 50 bias chamber, the drain flow rate from each of the control valves 29 and 50 increases, and the clutch control pressure Pc flowing through the clutch control pressure oil passage 28 increases. Further, the lubricating pressure PL flowing through the lubricating pressure oil passage 41 is controlled to decrease.

As a result, since the clutch control pressure Pc is gradually decreased with a certain delay after the lock-up engagement, the pressure at which the lock-up clutch 7c is engaged is sufficiently maintained. The lock-up clutch 7c can be quickly engaged. Further, following the decrease of the line pressure Ps during the lock-up coupling,
Since both the clutch control pressure Pc and the lubrication pressure PL are reduced, interference of the pressures with each other is avoided, and noise in the circuit such as surge noise can be reduced.

On the other hand, when releasing the lock-up clutch 7c, the valve body 46d of the lock-up control solenoid valve 46 is moved backward. Then, while the clutch control pressure oil passage 28 and the working pressure oil passage 45 are cut off,
The operating pressure oil passage 45 is communicated with the drain oil passage 51, and the operating pressure P supplied to the operation chamber of each of the control valves 29 and 50.
O is drained immediately through the check valve 53a, and the operating pressure PO supplied to the operation chamber of the lock-up control valve 40 is gradually drained through the throttle oil passage 52b having an orifice.

When the operating pressure PO supplied to the working chamber of the lock-up control valve 40 becomes lower than the biasing force due to the cooperation between the bias spring interposed in the bias chamber and the clutch control pressure Pc, As shown in FIG. 1, the release-side lubrication pressure oil passage 41 is connected to a release pressure oil passage 43, and the apply pressure oil passage 42 communicates with a drain oil passage 47. The release pressure PR having the lubricating pressure PL as the original pressure is supplied, and the apply pressure PAP supplied to the apply side is drained to release the lock-up clutch 7c.

As a result, when the lock-up is released, the clutch control pressure Pc and the lubrication pressure PL are immediately increased, while the lock-up clutch 7c is released with a certain delay. The lubricating pressure PL after the pressure is sufficiently increased is supplied to the clutch side, so that the lock-up clutch 7c can be reliably released and the oil flow supplied to the release side increases, so that the torque converter 7 can be efficiently cooled. Further, following the rise of the line pressure Ps at the time of lock-up release, the clutch control pressure P
Since both c and the lubrication pressure PL increase, interference between the pressures is avoided, and noise in the circuit such as surge noise can be reduced.

As described above, according to the present embodiment, the clutch control pressure Pc and the lubrication pressure PL follow the line pressure Ps that is variably set at the time of lock-up engagement and release.
Since the pressure difference Pd is variably set within a range of at least 1.5 kgf / cm ² , noise in the circuit such as surge noise can be reduced without increasing the capacity of the oil pump 21. Further, since the pressure control between the clutch control pressure Pc and the lubrication pressure PL is performed by using the switching operation of the lock-up control solenoid valve 46 for controlling the engagement and disengagement of the lock-up clutch 7c, the number of parts is reduced. Can be reduced,
Cost can be reduced.

FIG. 5 shows a second embodiment of the present invention. In this embodiment, between the lock-up control solenoid valve 46 of the working pressure oil passage 45 and the clutch control pressure control valve 29, the flow from the clutch control pressure control valve 29 to the lock-up control solenoid valve 46 is controlled. Allowable check valve 5
3a and a throttle oil passage 53b having an orifice are interposed in parallel, and a lock-up control solenoid valve is provided between the lock-up control solenoid valve 46 and the lubrication pressure control valve 50 of the working pressure oil passage 45. A check valve 54a for allowing the flow from the lubrication pressure control valve 50 to the lubrication pressure control valve 46 and a throttle oil passage 54b having an orifice are interposed in parallel.

As a result, at the time of lock-up coupling, when the operating pressure PO based on the clutch control pressure Pc flows into the operating pressure oil passage 45 through the lock-up control solenoid valve 46, the clutch control pressure control valve 29 Is supplied through a throttle oil passage 53b. Also, the lubrication pressure control valve 50
Is supplied immediately through the check valve 54a. On the other hand, when the lock-up is released, the operating pressure supplied to the working chamber of the clutch control pressure control valve 29 becomes the check valve 53.
a, the hydraulic pressure is immediately drained from the lock-up control solenoid valve 46 through the a, and the operating pressure supplied to the working chamber of the lubrication pressure control valve 50 is discharged from the lock-up control solenoid valve 46 through the throttle oil passage 54b. Is done.

Therefore, at the time of lock-up connection, first,
The lubrication pressure PL is reduced, and then the clutch control pressure Pc is reduced. On the other hand, at the time of lock-up release, first, the clutch control pressure Pc is increased, and then the lubrication pressure PL is increased.

As a result, the clutch control pressure Pc and the lubrication pressure P
By providing a certain time difference when switching L in accordance with the engagement and disengagement of the lock-up clutch 7c, there is no region where the pressure differences Pd are close to each other, and noise in the circuit can be reduced.

FIG. 6 shows a third embodiment of the present invention. In this embodiment, the first embodiment described above and the second embodiment
By combining and releasing the lock-up clutch 7c, the timing of the engagement and disengagement of the lock-up clutch 7c and the switching timing between the clutch control pressure Pc and the lubrication pressure PL are variably set by a combination of a check valve and an orifice. A region where the pressure differences Pd approach each other at the time of switching is eliminated, and noise in the circuit can be reduced.

[0076]

According to the first aspect of the present invention, the first pressure control valve for setting the pulley control pressure for the continuously variable transmission, the lock-up clutch by adjusting the drain pressure of the pulley control pressure, and the front and rear A second pressure control valve for setting a clutch control pressure for an operation clutch of the forward switching device, and a lubrication pressure for regulating a drain pressure of the clutch control pressure and supplying the release side of the lock-up clutch to the release side and a lubrication required portion. And a pressure difference between the pulley control pressure and the clutch control pressure, and the pressure difference between the clutch control pressure and the lubrication pressure are set to values that do not interfere with each other. It is possible to reduce noise in the circuit such as surge noise generated by the influence of pulsation of the pump, turbulence of the flow, and the like. Further, a pressure control working chamber provided in the second pressure control valve and the third pressure control valve and a lock-up working chamber provided in a lock-up control valve for shutting off supply of clutch control pressure to a lock-up clutch. Through a first hydraulic circuit, and disconnects the first hydraulic circuit and the second hydraulic circuit that circulates the clutch control pressure when the lock-up clutch is connected and when the communication is released. At the same time, the first hydraulic circuit is made freely communicable through the flow path switching means for leading to the drain oil passage. Therefore, at the time of lock-up coupling in which the torque ratio of the torque converter decreases, and in the case of lock-up release in which the torque ratio increases. The clutch control pressure and the lubrication pressure can be changed following the pulley control pressure that changes between lock-up release and lock-up engagement. Because, without increasing the capacity of the oil pump in any of the state of the lock-up disengagement, it is possible to reduce the circuit noise.

According to the second aspect of the present invention, in the first aspect of the invention, by setting the pressure difference to 1.5 kgf / cm ² or more, the noise in the circuit can be further reduced.

According to a third aspect of the present invention, in the first aspect of the present invention, the first hydraulic circuit is provided between the flow path switching means and the lock-up control valve by the flow path switching means. A check valve allowing flow to the lock-up control valve and a throttle oil passage are interposed in parallel, and the flow path switching means of the first hydraulic circuit, the second pressure control valve, and the third
Between the second pressure control valve and the third pressure control valve, and a check valve that allows flow from the third pressure control valve to the flow path switching means, and a throttle oil passage are interposed in parallel. When the lock-up clutch is engaged, the clutch control pressure decreases after the lock-up clutch is engaged, and when the lock-up clutch is released, the clutch control pressure increases before the lock-up clutch is released. When the pressure is low, the lock-up clutch is always engaged, and the engagement of the lock-up clutch can be reliably released.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the second pressure is provided between the flow path switching means of the first hydraulic circuit and the second pressure control valve. A check valve and a throttle oil passage permitting the flow from the control valve to the first hydraulic circuit are interposed in parallel, and the flow path switching means of the first hydraulic circuit and the third pressure control valve are further provided. In the meantime, the check valve and the throttle oil passage permitting the flow from the passage switching means to the third pressure control valve are interposed, so that when the lock-up clutch is engaged, the lubricating pressure becomes low. The clutch control pressure decreases, and when the lock-up is released, the clutch control pressure increases and then the lubrication pressure increases. Therefore, the pressure difference between the clutch control pressure and the lubrication pressure during lock-up clutch switching is close. And noise in the circuit can be reduced.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the flow path switching means is provided between the flow path switching means and the lock-up control valve of the first hydraulic circuit. A check valve allowing flow to the lock-up control valve and a throttle oil passage are interposed in parallel, and a check valve between the flow path switching means of the first hydraulic circuit and the second pressure control valve is further provided. A check valve for permitting the flow from the second pressure control valve to the flow path switching means and a throttle oil path are interposed in parallel, and the flow path switching means of the first hydraulic circuit is Since the check valve and the throttle oil passage that allow the flow from the flow path switching means to the third pressure control valve are interposed between the third pressure control valve and the third oil pressure control valve, when the lock-up clutch is engaged, first, After the lock-up clutch is engaged, the lubrication pressure decreases, then the clutch control pressure decreases, , When releasing the lock-up clutch,
First, since the lubricating pressure increases after the clutch control pressure increases, and then the lock-up clutch is released, the lock-up clutch is always engaged when the clutch control pressure is low. And the pressure difference between the clutch control pressure and the lubrication pressure at the time of lock-up clutch switching does not approach each other, so that noise in the circuit can be reduced.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a continuously variable transmission according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the lock-up control solenoid.

FIG. 3 is a block diagram showing an output system of the electronic control unit.

FIG. 4 is a schematic diagram showing a drive system of the continuously variable transmission.

FIG. 5 is a hydraulic circuit diagram of a continuously variable transmission according to a second embodiment of the present invention.

FIG. 6 is a hydraulic circuit diagram of a continuously variable transmission according to a third embodiment of the present invention.

FIG. 7 is a waveform diagram showing pressure fluctuation in a hydraulic circuit caused by pulsation of an oil pump and the like.

[Explanation of symbols]

7 Start clutch with lock-up clutch (torque converter) 7c Lock-up clutch 8 Forward / reverse switching device 9 Continuously variable transmission 11 Operating clutch (forward clutch) 21 Engine driven oil pump 27 First pressure Control valve (hydraulic control valve) 28 first hydraulic circuit (clutch control pressure oil passage) 29 second pressure control valve (clutch control pressure control valve) 45 second hydraulic circuit (operating pressure oil passage) 46 ... flow path switching means (lock-up control solenoid valve) 50 ... third pressure control valve (lubricating pressure control valve) 52a, 53a, 54a ... check valve 52b, 53b, 54b ... throttle oil path Pc ... clutch control pressure PL: Lubrication pressure Ps: Pulley control pressure (line pressure) Pd: Pressure difference

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // F16H 59:68

Claims (5)

[Claims] A drive system includes a starting clutch with a lock-up clutch, a forward / reverse switching device, and a continuously variable transmission, and controls a discharge pressure from an engine-driven oil pump to control a pulley control pressure for the continuously variable transmission. A first pressure control valve that is set low when the lock-up clutch is engaged and high when the lock-up clutch is disengaged; and a lock-up clutch applied to the starting clutch by regulating the drain pressure of the pulley control pressure. A second pressure control valve for setting a clutch control pressure for an operating clutch of the side and forward / reverse switching device; a drain pressure of the clutch control pressure being regulated and supplied to a release side of the lock-up clutch and a lubrication required portion. A third pressure control valve for setting a lubricating pressure, wherein the hydraulic control circuit of the continuously variable transmission comprises: The pulley pressure and the clutch control pressure, and the pressure difference between the clutch control pressure and the lubrication pressure are set to values that do not interfere with each other, and are provided in the second pressure control valve and the third pressure control valve. A pressure control operation chamber and a lock-up operation chamber provided in a lock-up control valve for shutting off supply of the clutch control pressure to the lock-up clutch through a first hydraulic circuit; And a second hydraulic circuit that circulates the clutch control pressure. When the lock-up clutch is connected, the communication is interrupted when the lock-up clutch is released, and a flow path switching unit that guides the first hydraulic circuit to a drain oil passage is provided. A hydraulic control circuit for a continuously variable transmission, wherein the hydraulic control circuit is configured to be able to communicate with each other via a motor. 2. The hydraulic control circuit for a continuously variable transmission according to claim 1, wherein the pressure difference is 1.5 kgf / cm ² or more. 3. A check valve and a throttle between the flow path switching means and the lock-up control valve of the first hydraulic circuit, the check valve allowing flow from the flow path switching means to the lock-up control valve. An oil passage interposed in parallel, and further comprising the flow path switching means of the first hydraulic circuit and the second hydraulic circuit.
Between the second pressure control valve and the third pressure control valve and the throttle oil passage between the third pressure control valve and the third pressure control valve. 2. The hydraulic control circuit for a continuously variable transmission according to claim 1, wherein the hydraulic control circuit is interposed in parallel. 4. A reverse valve which allows a flow from the second pressure control valve to the first hydraulic circuit between the flow path switching means of the first hydraulic circuit and the second pressure control valve. A stop valve and a throttle oil path are interposed in parallel, and the flow path switching means of the first hydraulic circuit and the third
2. A continuously variable check valve according to claim 1, further comprising a check valve and a throttle oil passage interposed between said pressure control valve and said third pressure control valve. Transmission hydraulic control circuit. 5. A check valve and a throttle between the flow path switching means and the lock-up control valve of the first hydraulic circuit, which allow flow from the flow path switching means to the lock-up control valve. An oil passage interposed in parallel, and further comprising the flow path switching means of the first hydraulic circuit and the second hydraulic circuit.
A check valve allowing flow from the second pressure control valve to the flow path switching means and a throttle oil passage are disposed in parallel between the pressure control valve and the first hydraulic circuit; A check valve and a throttle oil passage are provided between the flow path switching means and the third pressure control valve, the check valve allowing flow from the flow path switching means to the third pressure control valve. The hydraulic control circuit for a continuously variable transmission according to claim 1, wherein