JPH03239862A - Hydraulic control device of continuously variable transmission - Google Patents

Abstract

PURPOSE:To prevent belt slip at the time of restart by communicating a shift lock valve side in the closing direction of the spool of the opening and closing timing valve for shift lock release of the pitot pressure oil passage of a plunger and energizing a spring in the opening direction to communicate a primary cylinder side. CONSTITUTION:In the hydraulic control system of a continuously variable transmission, an opening and closing timing valve 170 is normally opened to introduce pitot pressure to a plunger 161, allowing shift lock judgment and shift lock operation. When a tire is locked at the time of braking on low mu road, a primary pressure is held high by a shift lock valve 84 to conduct shift lock, and the opening and closing timing valve 170 is closed. When gear change is then started by a gear ratio control valve 100, and the pitot pressure is generated, the opening and closing timing valve 170 is opened, and the pitot pressure acts on the plunger 161 to release the shift lock. Hence, a sharp reduction in primary pressure can be suppressed, and belt slip can be prevent in any case.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a hydraulic control device that mechanically controls line pressure and speed change in a belt-type continuously variable transmission for vehicles. This article relates to measures to prevent slippage in the event of tire locking during braking on roads such as µ-roads.

[Conventional technology]

Regarding hydraulic control of this type of continuously variable transmission, various proposals have already been made, including a gear ratio control valve that changes speed based on factors such as accelerator opening and engine speed, and a line pressure control valve that controls line pressure based on factors such as the gear ratio. It is equipped with regulating valves, etc. Here, each of these valves is based on the premise that the tires clip the road surface and the rotational state of the wheels is smoothly fed back to the engine rotational speed together with the primary pulley via the transmission. Therefore, if the tires lock up during braking on a low μ road such as a snowy road and the vehicle skids, the pulleys and belts together with the wheels rapidly decelerate and come to a stop. For this reason, the control of each valve in the hydraulic control system cannot follow the deceleration state in this case and becomes temporarily abnormal, which causes the shift control and line pressure control to become abnormal when the brake is released and recovered. Belt slip is likely to occur due to imbalance. From this, it is conceivable that measures should be taken to accurately cut off abnormal driving conditions such as tire lock and prevent a slip when the brakes are released to recover.

Conventionally, in the hydraulic control system of the above-mentioned continuously variable transmission, there is a prior art, for example, as filed in Japanese Patent Application No. 63240433 by the applicant of the present invention, regarding measures to prevent belt slip when the tires are locked. Here, when the tires are locked, the primary pressure is controlled to the lowest speed gear, even though the actual pulley and belt are locked to the high speed gear side, as the pit pressure decreases according to the engine speed. We are focusing on Therefore, tire lock is detected based on the gear ratio and pitot pressure, and in this case, the shift lock valve on the drain side of the gear ratio control valve is closed to maintain the primary pressure at high pressure and fix the gear ratio to the high speed side. . It has been shown that when the pulley and belt recover rapidly when the brake is released, belt slip is prevented by increasing the pressing force of the primary system pulley, which has a large inertial mass.

[Problem to be solved by the invention]

By the way, in the prior art described above, the shift lock is activated by determining the tire opening/ink based on the interaction between the gear ratio and the pitot pressure, and at the same time, the shift lock is released by determining that the tire has recovered from the lock. Therefore, there is no problem if the vehicle recovers after the tires are locked while driving, but it is inconvenient if the vehicle stops and restarts with the tires locked. In other words, when restarting, the shift lock state causes the vehicle to start in the high speed gear, and the pitot pressure gradually increases due to the start, and when it reaches the set pressure, the plunger swings the shift lock arm and closes the shift lock valve. Open operation. Then, the primary pressure rapidly drains and drops, leading to insufficient belt clamping force and belt slip, and furthermore, the rapid downshift deteriorates shift controllability.

The present invention has been made in view of the above, and its purpose is to prevent a sudden drop in primary pressure at the time of recovery after a shift lock in a hydraulic control system that performs a shift lock function without locking the tires. It is an object of the present invention to provide a hydraulic control device for a continuously variable transmission that can suppress belt slip and the like when starting after stopping in a stopped state.

[Means for resolving issues]

In order to achieve the above object, the hydraulic control device for a continuously variable transmission of the present invention is provided with a shift lock valve on the drain side of the gear ratio control valve, and between the shift lock valve and the plunger to which pitot pressure is guided. A shift lock arm is installed that becomes free only in high speed gears, and when the pitot pressure drops in high speed gears, it determines whether the tires are locked, and the shift lock arm operates the shift lock valve to maintain the primary pressure at a high level. In the hydraulic control system, an on-off timing valve for releasing the shift lock is installed in the pitot pressure oil path of the plunger, and one of the spools of the on-off timing valve is connected to the shift lock valve side in the closing direction, and the other side is connected in the closing direction. This biases the spring in the direction of the primary cylinder and connects the primary cylinder side.

[For production]

Based on the above configuration, in the hydraulic control system of the continuously variable transmission,
Under normal conditions, the on-off timing valve opens and pitot pressure is introduced into the plunger, making it possible to make shift lock decisions and shift lock operations. Therefore, if the tires lock during braking on a low μ road, the primary pressure is held at a high pressure by the shift lock valve and the shift is locked, and at this time the opening/closing timing valve closes. After that, when the gear ratio control valve starts shifting and primary pressure is actually generated, the opening/closing timing valve opens and pitot pressure acts on the plunger, releasing the shift lock. Sudden drop is suppressed and belt slip etc. are prevented in any case.

〔Example〕

Embodiments of the present invention will be specifically described below based on the drawings.

Referring to FIG. 1, a belt-type continuously variable transmission based on a front engine/front drive (FF) with a transverse transaxle and an electromagnetic powder clutch will be described.

No. n 1 is an electromagnetic powder clutch, 2 is a forward/reverse switching device, 3 is a continuously variable transmission, and 4 is a front differential device. An electromagnetic powder type clutch t is housed in one side of the clutch house synchronizer, and the main case 7 is connected to the other side of the clutch house synchronizer, and the main case 7 is connected to the clutch housing 6 of the main case 7 on the side opposite to χ/I. Inside the sight case 8, a forward/reverse switching device 2. Continuously variable transmission 3. A front differential device 4 is accommodated therein.

The electromagnetic powder type clutch l is integrally splined to the engine crankshaft 10 (through the drive plate 11 to the ring-shaped drive member 12 and transmission input shaft 13 in the rotation direction). It has a disk-shaped driven member 14. A coil I5 is built in the outer peripheral side of the driven member 14, and the drive member 12
A gap I6 along the circumference between and the driven member 14
A gap I6 is formed with electromagnetic powder in this gap I6. In addition, a power supply brush 19 is in sliding contact with the slip ring 18 of the hub portion of the driven member 14 equipped with the coil I5, and is further connected to the coil I5 through the inside of the driven member 14 from the slip ring 18 to form a clutch current path M. has been done.

In this way, when the clutch current is applied to the coil 15, the drive and driven member 12.1 are connected through the gap 16.
4, electromagnetic powder is combined and accumulated in the gap 16 in the form of a chain, and due to this binding force, the driven member 14 is integrally connected to the drive member 12 without slipping, and the clutch is connected. become a state. On the other hand, when the clutch current is cut, the drive due to the electromagnetic powder and the coupling force between the driven members 12 and 14 disappear, resulting in a clutch disengaged state.

If the clutch current in this case is controlled in conjunction with the operation of the forward/reverse switching device 2, it is possible to switch from the P (bar kink) or neutral to N range to the forward D (drive) or Ds (sporty drive) range. or R of retreat (
When switching to the reverse (reverse) range, clutch 1 is automatically crossed, eliminating the need for clutch pedal operation.

Next, the forward/reverse switching device 2 includes a human power shaft 13 from the clutch l and a primary shaft 20 disposed coaxially therewith.
established between. That is, the input shaft 13 is formed with a reverse drive gear 21 that also serves as a forward engaged side, and a reverse engaged side gear 22 is fitted to the primary shaft 20 so as to be rotatable at the same time. A counter gear 24. Gears 21, 22 are supported on a shaft 23. They are meshed with each other via an idler gear 26 supported by a shaft 25. A switching mechanism 27 is provided between the primary shaft 20 and the gears 21 and 22. The above gear 21.2 which is always in mesh here
4.26.22 is connected to the driven member 14 having the coil 15 of the clutch l, and corresponding to the fact that the inertia mass of this part is relatively large when the clutch is disengaged, the switching device l
N27 is connected to each gear 2 through a synchronizer 9430.31 by a sleeve 29 spline-fitted to the hub 28 of the primary shaft 20.

22.

As a result, in the neutral position of the P or N range, the sleeve 29 of the switching mechanism 27 is fitted only with the hub 28, and the primary shaft 20 is in the input position. It is separated from dl13. Next, when the sleeve 29 is engaged with the gear 21 side via the synchronizing mechanism 30, the primary shaft 20 is directly connected to the human power shaft 13, and the moving state is set in the D or Ds range.

On the other hand, when the sleeve 29 is conversely engaged with the gear 22 side via the synchronizer tll131, the human power shaft 13 is moved to the gear 22 side.
It is connected to the primary shaft 20 through 1°24, 26.22, and the engine power is reversed to enter the R range reverse state.

In the continuously variable transmission 3, a secondary shaft 35 is arranged parallel to the primary shaft 20, and both Id 120° 35
primary pulley 36. Secondary libri 37
An endless drive belt 34 is provided between both pulleys 3B and 37. The primary pulley 36 and the secondary pulley 37 are both divided into two parts, one of which is fixed pulleys 36a and 37a, while the other movable pulleys 36b and 37b are movable to make the pulley interval variable. is equipped with a hydraulic servo device 38, 39 which also serves as a piston, and a movable pulley 37b of the secondary pulley 37.
A spring 40 is biased in a direction to narrow the pulley interval.

Further, as a hydraulic control system, an oil pump 41 as an operating source is installed next to the primary pulley 36. This oil pump 4] is a high-pressure gear pump, and the pump drive shaft 42 penetrates through the primary pulley 36, the primary shaft 20, and the human power shaft 13, and is directly connected to the crankshaft IO, so that the oil pressure is constantly maintained during engine operation. 7-l-.

It's starting to look like this. Then, the oil pressure of the oil pump 41 is controlled to supply and drain oil to each hydraulic servo device 38 and 39, and the gap between the primary pulley 36 and the secondary pulley 37 is changed to an inverse relationship, so that the pulley of the drive belt 34 The pulley ratios in 3B and 37 are converted steplessly, and steplessly variable power is output to the secondary shaft 35.

In view of the fact that the minimum pulley ratio on the high speed side of the continuously variable transmission 3 is very small, for example 0.5, and therefore the rotational speed of the secondary shaft 35 is high, the front differential device 4 has a An output shaft 44 is connected via a pair of intermediate reduction gears 43a and 43b. A final gear 46 meshes with the drive gear 45 of this output shaft 44, and transmission is configured from the final gear 46 to the left and right front wheel axles 48a, 48b via a differential mechanism 47.

In FIG. 2, the hydraulic control system of the continuously variable transmission 3 will be explained. In the primary hydraulic servo device 38, a movable pulley 36b is engaged with a cylinder 38a that is integrated with the primary shaft 20, and supplies and discharges air into the cylinder 38a. It produces primary pressure due to sacrificial pressure.

In addition, in the secondary surface pressure surfing device 39, a movable preform 37b is attached to a cylinder 39a that is integrated with the secondary shaft 35.
are fitted, and line pressure is introduced into the cylinder 39a.

Here, the movable pulley 36b has a larger pressure receiving area than the movable pulley 37b, making it possible to perform speed change control using only the primary pressure.

The oil pumped up from the oil reservoir 70 by the oil pump 41 is passed through the oil passage 71a to the line pressure regulating valve 90.
A line pressure oil passage 71 that is guided by the oil passage 71a and branches from the oil passage 71a.
b, the line pressure is constantly introduced into the secondary cylinder 39a. The oil passage 71c branching from the oil passage 71a communicates with the gear ratio control valve 100, and the oil passage 71c branches from the oil passage 71a.
An oil passage 72 is communicated between the primer cylinder 38a and the primer cylinder 38a. Further, a pitot pressure sensor 73 is installed at the primary cylinder 38a to take out a pitot pressure as a control pressure corresponding to the engine speed in clutch engagement and subsequent gear change control, and the pitot pressure from this pitot pressure sensor 73 is Line pressure regulating valve 90 via oil passage 74. Gear ratio control well 1o
Guided by O.

Furthermore, in contrast to the D range, which performs shift control over a wide range including low engine speeds, the hydraulic pressure control is limited to a high engine speed range to obtain the Ds range, which applies engine braking when the accelerator is released. As a system, a relief valve 76 is provided in the drain oil path 75a from the line pressure adjustment valve 9o, and is connected to either the oil path 75b of the lubrication hydraulic circuit that branches from the upstream side of the relief valve 76, or to the select position detection valve 13[]. The oil passage 7 further branches from the oil passage 75b.
5c communicates with the engine brake actuator 140 of the gear ratio control valve 100.

Oil passage 75d branching from oil passage 75a of the lubrication hydraulic circuit
is a belt lubricating nozzle 7 arranged on the inner circumference of the belt 34
7, the oil passage 75e communicates with the oil supply lower 8 of the pitot pressure sensor 73, and the oil passage 75e communicates with the oil a 70 via the check valve 79° oil cooler 80. A balancer chamber 3 is located on the opposite side of the hydraulic chamber 39b of the secondary cylinder 39a.
9c is provided, and the outlet side oil passage 81 of the oil cooler 80 communicates with the balancer chamber 39c and fills it with oil.
The centrifugal oil pressure of 9b is offset by the balancer chamber 39c. In addition, the drain oil passage 82 of the gear ratio control valve 100
A shift lock valve 8 is provided with a check valve 83 in the middle of the shift lock valve 8.
4 are provided, and the oil passages 82 and 75 upstream of the check valve 83
A pre-feeling oil passage 85 communicates with b.

In addition, in the middle of each oil route.

An orifice 86 is provided in the atmospheric opening.

The line pressure regulating valve 90 has a valve body 91. A sensor shoe 95 has a spring 94 biased between the spool 92 and one bush 93 of the spool 92, and engages with the primary movable pulley 36b to detect the actual gear ratio. It is movably supported by a tube 96 and connected to a bushing 93. In the valve body 91, the pitot pressure of the oil passage 74 is connected to a port 91a on the opposite side of the spring 94 of the spool 92, and the drain port 9 is connected to this port 91a.
A balance chamber 91c is disposed through 1h, and normally line pressure acts thereon. Further, there are a port 9Id and a tren port 91e adjacent to the port 91c to which line pressure is introduced, and the land chamfer portion 92a of the spool 92 changes the amount of tren to adjust the pressure. 2 stages of line pressure tJ on the spring 94 side of
A J replacement port 91r is also provided.

On the other hand, a line pressure oil passage 7]C is provided with a solenoid valve 97 for switching line pressure into two stages. This two-stage line pressure switching solenoid valve 97 is a three-way valve, and selectively communicates the oil passage 98 connected to the two-stage line pressure switching port 91'' with the oil passage 71c side and the train side. Oil passage 7 is turned on by energization.
1c and 98 are connected to create a line pressure two-stage switching port 91.
1, and drains the oil passage 98 by de-energizing it.

In this way, the spring force of the spring 94 of the spool 92 increases as the gear ratio increases, and this spring force acts on the line pressure increase expansion 1. In addition, the balance room 91.
c and the line pressure of the line pressure two-stage switching port 91r act on the line pressure low side, and the line pressure is controlled by the balance between these two. The pitot pressure at the end of spool 92 acts to adjust the balance point of spool 92 as pump displacement changes with engine speed.

Therefore, the spring force F at the balance point of the spring 94 is
, line pressure P11. Assuming that the pressure receiving area difference between the port 91c and the line pressure two-stage switching boat 91 is AL and Ac, when the line pressure two-stage switching solenoid valve 97 is de-energized, A1.・PL=F holds. The line pressure is high-pressure controlled by Pl,=F/AL.

Also, when the solenoid valve 97 is energized, (AI, +Ac
)・Pl,,=F is established, and the line pressure is Pl, -F/(AL +Ac)
Controlled by low pressure. In this way, the line pressure is steplessly controlled by the spring force that changes according to the gear ratio, and furthermore, the line pressure is controlled in two levels, low and high, by the two-stage line pressure switching solenoid valve 97, and the pulley is pressed. It begins to generate power.

The gear ratio control valve 100 has a sprue 1 on one side of the valve body 101.
02, and a port 101a at one end of the spool 102 has a pitot pressure check valve 103 or an orifice 104.
and a low peat spring 105. at the other end. The high speed spring 106 is energized. Further, the central port 101b of the spool 102 is connected to the oil passage 72, and the ports 10Ic and 101d on the left and right sides thereof are connected to the drain oil passage 82. Line pressure oil passage 71. c, communicates with spool 102
The primary cylinder 38a is supplied by the bay part 102a,
It is designed to discharge water and generate primary pressure.

The other side of the valve body 101 has a plunger 107, and one end of a rod 108 is connected to the plunger 107 with a spring 1.
09 and roller 1 at the other end of the rod 108.
Shift cam 11 rotates according to the accelerator opening at 08a.
0 comes into sliding contact. A guide 'llll is attached to the plunger 107 and receives the spring 105, thus changing the force of the spring 1050 in accordance with the simultaneous movement of the shift cam 110. Here, the plunger 107 has an oil passage 7.
4 is guided, and the spring reaction force acting on the plunger 107 is received by the pitot pressure, and the shift cam I
11 is designed to reduce the operating force required.

Furthermore, a mechanical modulator [120] is provided between the plunger 1.07 and the spring 10G.

This modulator mechanism 120 has a variable mechanism 1i2i between the plunger 107 and the receiver 1.12 of the spring 106 inside the guide 1.11, and this variable mechanism 121 is connected to the sensor shoe 95 via a link 122. Destroy.

Then, as the gear ratio shifts to a higher speed gear, the variable machine 19121 acts as a modulator to gradually increase the force of the spring 10B.

In this way, the pitot pressure and the force of the spring 105 corresponding to the accelerator opening by the shift cam 110 act on the spool 1 (12).Then, the balance between these two produces a predetermined primary pressure to determine the gear ratio, and as the vehicle speed increases, the force of the spring 105 acts on the spool 1 (12). In response to the increase in pressure, the gear ratio is controlled to upshift to a high speed gear.At this time, the force of the spring 106 according to the gear ratio is further applied to the spool 102 by the modulator mechanism 120, so that the gear ratio is shifted to a higher gear. The engine speed will gradually increase in response to the upshift.

The select position detection valve 130 has a drain hole in the valve body 131! A cam 13 that rotates in response to the operation of the select lever 13B is inserted into the valve body 133.
5 is the contact. Here, in the cam 135, D, N
, R range position is on the convex part 135a, P and D at both ends
The range position of s is the curved part 135b, and as described above,
Drain holes 132 are closed in each of the N and R ranges to generate operating oil pressure. Also, drain hole 132 in P and Ds ranges.
When opening, the oil passage 75a on the upstream side is opened by the orifice 86.
It is designed to prevent a drop in oil pressure.

The engine brake actuator 140 has a piston 142 inserted into a cylinder 141.
The return spring 143 is biased to one side of the piston chamber +44, and the operating hydraulic pressure of the extraction passage 75b is guided to the other piston chamber +44 via the oil passage 75c. Also, the hook 142a at the tip of the piston 142, the rod 10 of the gear ratio control valve 10 [)
A lever 1413 of a modifying mechanism 145 for correcting Ds range characteristics, which also serves as a push-in lever, is engageably provided between the roller pin togb of g and the sensor shoe 95.

In this way, when there is no operating oil pressure in the P and Ds ranges, the lever 146 is swung by the hook 142a of the piston 142 to forcibly push the rod 108 to a predetermined stroke;
The speed change range is limited to the high engine speed side, thereby applying engine braking in the Ds range. When a predetermined gear ratio is reached in this state, the sensor shoe 95 engages with the lever 146, and thereafter, as the gear ratio increases, the lever 146 swings in the opposite direction by the sensor shoe 95, and the piston 142 , causing the rod 108 to be pulled back to the forward dimension position.

Referring to FIG. 3, measures to prevent belt slip when tires are locked will be described.

In the figure, reference numeral 150 is a valve block, and the body 151 and plate 152 of this valve block 150 are
The line pressure regulating valve 90 shown in FIG. 2 is installed inside and outside of the. Gear ratio control valve 100. Modulator machine IM120. A modifying mechanism 145 and the like is installed, and a shift locking mechanism 160 is also installed as a measure to prevent belt slip when the tires are locked.

As already mentioned, the shift lock mechanism 160 has a shift lock valve 84 attached to the check valve 83 of the drain oil passage 82 from the gear ratio control valve 100, and a shift lock valve 84 on the side opposite to the shift cam 110 of the valve block 150. A plunger 161 is installed on the same side as the valve 84. And these shift lock valves 84. A shift lock arm 165 is mounted between the plunger 161 and the sensor shoe 95.

The check valve 83 is connected to the spool 84 of the shift lock valve 84.
A ball 83C biased by a spring 83b is provided inside the cylinder b to regulate the amount of drain from the drain oil passage 82, and when the primary cylinder 38a is drained at the maximum gear ratio, it is filled with oil and prefilled. It is something that works.

Further, the spool 84b of the shift lock valve 84 is movably inserted into the cylinder 84a of the shift lock valve 84 to open and close the drain port 84c. Also, a port 184g from the cylinder 84a is connected to a spring receiver 84f integrated with the spool 84b of the shift lock valve 84.
It is installed so that it is in contact with the Here, the spring receiver 84'' includes the inside of the spool 84b and the port shaft 84.
A communication hole 84h is provided that communicates the side that contacts the shift lock valve 84, and since oil flows into the spool 84b of the shift lock valve 84, a port 8 is provided to drain this oil.
4d 84e is the cylinder 8 of the shift lock valve body 84
4a and spool 84b, these ports 84
d.

84e coincide with the drain port 840 of the cylinder 84a, which is formed facing the ball 83c of the check valve 83, in the open position, but are set in a relationship that does not match in the closed position of the drain port 84C. When the drain port 84C is in the closed position, high primary pressure is applied behind the spool 84b of the shift lock valve 84 to self-lock the port shaft 84C.
The drain from 4g is configured to divide the self-lock by an angle q.

The plunger 161 is pushed into a cylinder 162 that communicates with the pitot pressure oil passage 74, moves in accordance with the pitot pressure, and detects its magnitude. The relatively large normal pitot pressure in the high speed stage is the tip 161 of the plunger IB1.
a protrudes higher than tenon-151.

The shift lock arm iB5 has a substantially rectangular shape on the back side, and has a shift lock valve 84 on one side of a parallel connecting part 165a.
．． The plunger 161 is connected to the (+Iy piece 165b, and the other side is connected to the spring receiver 165C and the sensor shoe 95.
It is swingably mounted using the spring receiver 16.
Spring 186 (=J force is applied to 5C. Engagement J'1
1B5d extends directly below the sensor knee 95, and at a gear lower than a predetermined gear ratio IS (for example, 10), the straight portion 165e engages with the pin 95a on the sensor shoe 95 side.
Swinging of arm 165 is limited. In addition, at higher speeds than this gear ratio 1s, the restriction by the sensor knee 95 is released, and if the pitot pressure constantly decreases due to this tea juice, the brakes on low μ roads, especially the tire lock, will actuate the arm 165. It is supposed to be done. Furthermore, a taper 1651 is provided at the tip of the engagement piece 165d to enable return of the engagement between the pin 95a and the arm i65 by movement of the sensor knee 95.

The arm 165 is normally tilted by the action of the planer 1.61 or the sensor shoe 95, and is set horizontally by a spring 166 when the tire is long. Then, when the adjustment screw l;
4" comes into contact with the port shaft 84g.

On the other hand, when the arm 165 becomes horizontal, the adjustment 1137
The port shaft 84g and the spring receiver 84f are pushed in through the spool 84b and the drain boat 84C is moved.
is closed, and in this state, the oil inside the spool 84b flows into the port shaft 84g side through the communication hole 84h formed in the spring receiver 84'', and when the pressure of this oil increases, the pressure between the spring receiver 84r and the sprue 84b increases. The surface pressure receiving area becomes larger than the product of the pressure receiving width j inside the spool 84b, the drain port 84 is closed, the arm 165 is tilted and the adjustment screw 167 is exposed above, and the contact area between the spring receiver 84f and the port shaft 114g is When opened, the spool 84b is securely self-locked until the oil on the port shaft 84g side is drained, and the boat 84c is closed so that the oil in the oil passage 82 is not drained.

On the other hand, the shift lock machine tM1[io is provided with a shift lock release means when the tire lock is recovered, and the shift lock is locked by utilizing the timing when the human pressure increases and the gear ratio control valve 100 performs an upshift. is designed to be released. Therefore, in the pitot pressure oil passage 74, the plunger! An opening/closing timing valve 170 is installed in a portion of the cylinder 61 communicating with the cylinder 1.62. This opening/closing timing valve 1
70 is provided so that spools 171 having different pressure receiving areas open and close the pitot pressure oil passage 74, and are biased by a spring 1.72 in the opening direction. Further, the oil passage 82 on the shift lock valve 84 side communicates with the side of the spool 171 having a larger pressure receiving area, and is closed by the shift lock pressure Pa. The oil passage 72 of the primary cylinder 38a communicates with the side of the spring 172 having a smaller pressure receiving area, and is opened at tM so that the opening operation is performed again when the primary pressure Pp becomes higher than the shift lock pressure Pa after the tire is locked.

Next, the operation of the continuously variable transmission control system configured as described above will be explained.

First, before the vehicle stops or starts shifting at the start of running, the line pressure regulated by the line pressure regulating valve 90 is applied to the oil passage 71.1).
Therefore, it is introduced only in the secondary cylinder 39a,
The primary cylinder 38a communicates 17 with a drain oil passage 82 through a gear ratio control valve 100. Therefore, in the continuously variable transmission 3, the winding of the secondary pulley 37 around the primary pulley 36 of the drive belt 34 has the largest diameter, resulting in a low speed stage with a maximum gear ratio i.

Then, after driving, the pitot pressure of the pitot pressure sensor 73 increases and the gear ratio control valve 1. (When the spool I[]2 of 10 is moved and the line pressure of the oil passage 71c is supplied to the primary cylinder 38a via the oil passage 72, primary pressure is immediately generated by the prefill action and an upshift is started.

Then, as the primary pressure increases, the diameter of the winding of the drive belt 34 around the primary pulley 36 increases, and finally the speed is continuously variable to a higher speed stage than the minimum gear ratio.

Therefore, in the above-mentioned speed change control, in the low speed gear, the engagement piece 165d of the shift lock arm 165 engages with the pin 95a of the sensor shoe 95 in the shift lock device tM16o to limit the swinging, as shown in FIG. Therefore, when the vehicle is stopped and the pitot pressure is zero, or when the vehicle is running at low speed and the pitot pressure is small, the shift lock arm 165 is held tilted. Therefore, the port shaft 84g of the shift lock valve 84
protrudes outward, and the sprue 84b moves backward to open the drain port 84c, allowing draining. Therefore, even when the gear ratio control valve 100 is communicated with the primary cylinder 38a or the drain oil passage 82 through the ports 101b and 401c, it is freely drained from the drain port 84C of the shift lock valve 84 via the check valve 83, and the maximum speed can be changed. After the vehicle is running, the primary cylinder 38a is refueled and the primary pressure becomes higher, and as a result, the gear ratio is upshifted from the maximum gear ratio. In this way, it is ensured that the gear change control in the low gear is always performed normally.

When the pitot pressure corresponding to the engine speed increases with the vehicle speed, the plunger tet is strongly pushed out by the pitot pressure to keep the shift lock arm 185 in the above-mentioned inclined state. Therefore, even after the pin 95a of the sensor knee 95 comes off the arm 165 by moving to the right side in FIG.
The oil flows through the check valve 83 to the drain port 84c.
It becomes possible to drain from the tank, allowing for free gear changes such as kickdown. Further, when downshifting occurs during deceleration, the sensor shoe 95 moves to the left in FIG. 3, and the pin 95a engages with the shift lock arm 165 again, returning to the above-mentioned state.

On the other hand, when the shift lock arm 165 is tilted as described above, the oil pressure in the oil passage 82 is set to the lowest level at the check valve 83, so the spool 171 in the opening/closing timing valve 170 is connected to the spring 172 and the primary pressure Pp.
Opening operation is performed by Therefore, the pitot pressure in the pitot pressure oil passage 74 always acts on the plunger 161 in the cylinder 1B2, making it possible to detect tire lock as described above.

Next, in a high speed gear such as the minimum gear ratio, the shift lock arm 165 comes off the sensor shoe 95 and becomes swingable, and under this condition, when braking on a low μ road, as shown in FIG. 4(a),
As shown in (b), when the pit pressure pt suddenly decreases with the wheel speed Vw and the tire locks, the amount of thrust of the plunger 1131 decreases and the shift lock arm 165 is moved by the spring 161 as shown by the dashed line in FIG. It swings almost horizontally. Therefore, the shift lock valve 84 pushes down the spool 84b via the port shaft 114g to close the drain port 84C, and the contact portion between the port shaft 84g and the spring receiver 84'' is also closed by the movement of the adjustment screw 167. Therefore, even if the gear ratio control valve 100 connects the primary cylinder 38a to the drain oil passage 82 due to a decrease in pitot pressure, the high shift lock pressure Pa as shown by the broken line in FIG. Contained on the upstream side.

Thus, the primary pulley 36. Secondary pulley 3
7 and the belt 34 are stopped and held on the high-speed gear side due to tire lock, and the shift is locked.In the hydraulic control system, the primary pressure Pp of the primary cylinder 38a is also held at high pressure at the shift lock pressure Pa, and the shift is locked. become.

In addition, at this time, the shift lock valve 84
84d and 84e are misaligned, and the contact portion between the port shaft 84g and the spring receiver 84f is also closed, causing the cylinder 84a to close.
The inside of is sealed. Therefore, high primary pressure acts inside the cylinder 84a behind the spool 84b, and the check valve body 83a is moved to the closed position due to the difference in the pressure receiving area of the cylinder 84a and the pressure receiving area of the oil that pushes up the spool 84b and opens the port 84c. The primary pressure is self-locked to ensure high pressure retention.

Furthermore, when the tires are locked, the shift lock pressure Pa of the oil passage 82.72 acts equally on both sides of the spool 171 of the opening/closing timing valve 170. For this reason, spool 1
71 closes due to the difference in pressure receiving area and opens the pitot pressure oil passage 74.
This prevents the introduction of pitot pressure into the plunger 161, that is, the release of the shift lock solely by the pitot pressure.

Next, a case will be described in which the vehicle body speed vm becomes zero and the vehicle stops and starts again as shown in FIG. 4(a) in such a tire locked state. In this case, the primary pressure Pp is maintained at a high pressure to start the vehicle at a high speed, and after the start, the pitot pressure pt acts on the spool 102 of the gear ratio control valve 00 in accordance with the upper H of the pitot pressure pt. Then, when the force due to the pitot pressure pt becomes greater than the splinter force corresponding to the throttle opening and moves to the sprue 102 or the supply device, the port 101
The shift lock pressure Pa is confined in the oil passage 82, and the line pressure is supplied to the primary cylinder 38a by communicating with the oil passage 7c and 72, and the primary pressure Pp is changed to the primary pressure Pp in FIG. 4 (C). ).Therefore, at this time r;':
At j j 1, the opening/closing timing valve 170 is opened by the pressure between the primary pressure Pp and the shift lock pressure Pa, and the pitot pressure pt is introduced into the plunger 161 to cause the shift lock arm 165. The shift lock valve 84 is reset, and the shift lock pressure Pa immediately decreases to release the shift lock.

At this time, if the primary pressure Pp is higher than necessary, it is adjusted by the gear ratio control valve I00 to make it appropriate, and the normal gear shift 1. Return to Sugo. In this way, by releasing the shift lock after the shift control is started and the predetermined primary pressure Pp is set, sufficient belt clamping force is ensured with less drop in the primary pressure Pp. This will prevent slips and the like.

Also, if you release the brakes and continue driving after the tires are locked, the PT rises and the gear shift resumes quickly.
It operates similarly to 1 and returns. In this case as well, when recovering from a tire lock, the primary pressure Pp is held at a high pressure and the belt clamping force of the primary pulley 36 is large, so that the belt 34 rotates without slipping against the inertia mass on the primary pulley 36 side. .

Although the embodiments of the present invention have been described above, the installation location of the opening/closing timing valve 170 is not limited.

〔Effect of the invention〕

As described above, according to the present invention, in the surface pressure control system of a continuously variable transmission, in the case of tire lock, especially when braking on a low μ road, after primary pressure is actually generated at shift lock node jtL, Release the shift lock and return, so
A sudden drop in primary pressure is prevented. For this reason, it is possible to prevent a crash when restarting the vehicle after stopping with the tires locked, and gear shifting becomes smoother.

Furthermore, since the groove bottom is used to release the shift lock by comparing the shift lock pressure with the actual primary pressure using the opening/closing timing valve, the timing can be precisely determined and the structure is simple.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a continuously variable transmission to which the present invention is applied, Fig. 2 is a hydraulic circuit diagram showing an embodiment of the surface pressure control device of the present invention, and Fig. 3 is a configuration diagram of the main parts. , Figure 4 is a characteristic diagram of each part when the tires are locked. 3... Continuously variable transmission, 72 Primary pressure oil path, 74
... Pitot pressure oil passage, 83 ... Check valve, 84 ... Shift lock valve, 100 ... Gear ratio control valve, 160
・Shift lock mechanism, l...Plunger, 165...
Shift lock am, 170...Opening/closing timing valve, 1
71...Spool, 172...Spring

Claims (1)

[Claims] A shift lock valve is provided on the drain side of the gear ratio control valve,
A shift lock arm that becomes free only on the high speed gear side is installed between the shift lock valve and the plunger to which the pitot pressure is guided, and when the pitot pressure decreases in the high speed gear, it determines whether the tires are locked and locks the shift lock arm. In a hydraulic control system that operates the shift lock valve using an arm to maintain the primary pressure at a high pressure, an open/close timing valve for releasing the shift lock is installed in the pitot pressure oil path of the plunger, and one of the spools of the open/close timing valve is installed in the pitot pressure oil path of the plunger. A hydraulic control device for a continuously variable transmission characterized by communicating a shift lock valve side in a closing direction, urging a spring in the other opening direction, and communicating a primary cylinder side.