JPH0670463B2 - Hydraulic control of automatic transmission - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic control device for an automatic transmission of a vehicle.

[Prior Art] The hydraulic circuit is automatically controlled by the output of the microcomputer based on the input signals such as engine load, engine speed, vehicle speed, etc., and this hydraulic circuit activates each hydraulic actuator that drives the clutch mechanism and shift rod. An automatic transmission adapted to this has already been proposed in, for example, Japanese Patent Laid-Open No. 54-96659.

However, in the conventional automatic transmission, if an electrical failure should occur, the electromagnetic switching valve may malfunction and the following irregular gear shifting operation may be performed. That is, in a general gear transmission, the shift rod that shifts between the reverse speed and the first speed or a predetermined forward speed is operated by the three-position operation hydraulic actuator. When shifting up from the first gear to the second gear, the shift rod first returns from the first gear to the neutral position. It happens to control the hydraulic circuit of the hydraulic actuator that operates the reverse and first gear shift rods.
If one or both of the paired solenoid operated directional control valves fails and the supply of pressure oil to one end chamber of the hydraulic actuator is cut off, the shift rod shifts to the reverse gear position beyond the neutral position and the vehicle suddenly moves backward. There is a problem of doing.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to prevent overtravel to the rearward position when returning the shift rod from the shift position of the forward position combined with the reverse position to the neutral position, It is to provide a hydraulic control device for an automatic transmission.

[Means for Solving the Problems] In order to achieve the above object, the structure of the present invention has a shift rod that achieves meshing between a reverse gear and a predetermined forward gear, and a three-position operation type connected to the shift rod. The hydraulic actuator, a hydraulic switching valve inserted and connected between the hydraulic power source and the hydraulic actuator, D, N, a hydraulic switching valve for switching to the R range, and is inserted and connected between the hydraulic power source and one end chamber of the hydraulic actuator, A first electromagnetic switching valve that shifts the shift rod to a predetermined forward stage, and a second electromagnetic switching valve that is inserted and connected between the hydraulic source and the other end chamber of the hydraulic actuator to shift the shift rod to the reverse stage. A normally-closed malfunction prevention valve that is opened between the second electromagnetic switching valve and the other end chamber of the hydraulic actuator by being pushed by the hydraulic pressure from the first electromagnetic switching valve to the one end chamber. It is obtained by inserting connection.

[Operation] In a three-position operation type hydraulic actuator for driving a shift rod, an electromagnetic switching valve for obtaining a predetermined shift speed is inserted and connected between a hydraulic power source and one end chamber of the hydraulic actuator,
In addition, the normally closed malfunction prevention valve is opened by the hydraulic pressure to the one end chamber, and the electromagnetic switching valve and the malfunction prevention valve are inserted and connected in series between the hydraulic pressure source and the other end chamber. Unless hydraulic pressure is applied, pressure oil is not supplied to the other end chamber even when the solenoid switching valve is connected to the hydraulic pressure source.When pressure oil is supplied to one end chamber, pressure oil is always supplied to the other end chamber. Therefore, the shift rod will stop in the neutral position and will not go too far into reverse.

[Embodiment of the Invention] As shown in FIG. 1, a hydraulic pressure switching valve A is inserted and connected between a hydraulic power source 12 and a hydraulic pressure control circuit B for driving a shift rod. The hydraulic pressure switching valve A is configured by fitting the spool 2 into the valve chamber 16 of the housing 3, and has a hole 2a provided at the end of the spool 2.
A selector lever (not shown) for switching the P, R, N, D, 2, L ranges (operating mode) is connected to the spool lever. When the selector lever is switched to the D-N-R range, the spool 2 is D,
Switch to each position of N and R.

In order to keep the spool 2 in a predetermined range, a spring 6 holds a ball 6 which is urged to three recesses 7 of the spool 2 by a cylindrical portion provided in the housing 3. The valve chamber 16 has ports 8 and 18 connected to the hydraulic power source 12, a port 15 connected to the hydraulic control circuit B, and ports 13 and 1 connected to the tank 17 at all times.
4 and a port 19 opposite to the port 18 are provided.

On the other hand, the spool 2 is provided with the annular grooves 11, 10, 9 and the annular groove 1
1 is an R range in which the ball 6 of the day tent mechanism 5 is engaged with the recess 7 on the right side of the spool 2, and the port 18 is connected to the port 19. The annular groove 9 connects the port 8 to the port 15 in the D range where the ball 6 is engaged by the recess 7 on the left side of the spool 2. The spool 2 is provided with an axial passage 23 and a radial passage 24 connected to the passage 23. When the spool 2 is in the N range shown in the drawing, the port 19 has the passages 24 and 23 and the left end of the valve chamber 16. Connect to port 13 via chamber 25.

The hydraulic control circuit B is composed of six electromagnetic switching valves 31 to 36. Each of the electromagnetic switching valves 31 to 36 is in the illustrated state when the solenoids 31a to 36a are demagnetized, and is switched from the illustrated state when the solenoids 31a to 36a are energized, and is connected to the port 15.
Pilot hydraulic pressure from acts on the spool.

The three-position operation type hydraulic actuator C is a hydraulic actuator 41 that drives a shift rod 54 that obtains a shift between the fourth gear and the fifth gear, and a shift rod 55 that obtains a shift between the second gear and the third gear.
And a hydraulic actuator 43 for driving a shift rod 56 for obtaining a reverse speed and a first speed. Since the hydraulic actuators 41 to 43 have exactly the same configuration, only the hydraulic actuator 41 will be described.

The hydraulic actuator 41 has a small diameter cylinder 58 and a small diameter piston.
59, the cylindrical large-diameter piston 61 is fitted into the large-diameter cylinder 62, respectively. The large-diameter piston 61 is fitted with the intermediate piston 60, and is abutted with or integrally formed with the small-diameter piston 59. The small diameter piston 59 is connected to the shift rod 54. When pressure oil is supplied from the hydraulic pressure source 12 to both the end chamber 57 of the small diameter cylinder 58 and the end chamber 63 of the large diameter cylinder 62, the pressure oil is held at the neutral position shown in the figure. Large-diameter piston (not shown)
When the 61 and the small diameter piston 59 are separated from each other, the intermediate chamber between them is always connected to the tank 17.

The end chambers 57 and 63 of the hydraulic actuators 41 to 43 are connected to the hydraulic source 12
Or to connect to tank 17, first in each end chamber 57,63
The second electromagnetic switching valve is connected. That is, to explain the case of the hydraulic actuator 41, pressure oil is sent from the passage 22 connected to the hydraulic power source 12 to the large diameter cylinder 62 through the electromagnetic switching valve 31, or the oil of the large diameter cylinder 62 is connected to the tank 17. Returned to 21. Also, from the passage 22 to the solenoid switching valve 32
The pressure oil of the small diameter cylinder 58 is sent via the above, or the oil of the small diameter cylinder 58 is returned to the passage 21. Solenoid switching valve 31, 32
Normally, the end chambers 57 and 63 are connected to the tank 17 in the state shown by the force of the return springs 31b and 32b, and when excited, the spool moves against the force of the return springs 31b and 32b. , End room 5
Configured to connect 7,63 to hydraulic source 12.

According to the present invention, the malfunction prevention valve 71 is inserted and connected to the circuit of the hydraulic actuator 43 which drives the shift rod 56 of the shift speed (the first speed in the illustrated embodiment) combined with the reverse speed. In the malfunction prevention valve 71, a stepped piston 77 is fitted in a stepped cylinder 73 provided in a housing 72, and a spring 78 urges the stepped piston 77 toward the large diameter cylinder side. The port 79 provided on the end wall of the small diameter cylinder is connected to the electromagnetic switching valve 36. In addition, ports 74 and 76 facing each other are provided on the peripheral wall of the large diameter cylinder.
The port 74 is connected to the electromagnetic switching valve 35, and the port 76 is connected to the end chamber 63 of the large diameter cylinder 62 of the hydraulic actuator 43 (which becomes a hydraulic working chamber for obtaining a shift to the reverse gear). When the stepped piston 77 moves to the left against the spring 78, the ports 74 and 76 are connected by the annular groove 75 provided in the peripheral wall of the stepped piston 77. The intermediate chamber of the stepped cylinder 73 is always connected to the tank 17.

Next, the operation of the device of the present invention will be described. When normal traveling, that is, when the selector lever is set to the D range, as shown in FIG. 2, the recess 7 on the left side of the spool 2 of the hydraulic switching valve A is engaged with the ball 6 of the day tent mechanism 5. At this time, pressure oil is supplied from the hydraulic pressure source 12 to the port 8, the annular groove 9 and the port 15.
It is supplied to the passage 22 via. On the other hand, the passage 21 is connected to the tank 17. The port 19 connected to the passage 26 is closed. The electromagnetic switching valves 31 to 36 forming the hydraulic control circuit B are selectively excited by the microcomputer according to the vehicle speed, engine speed, engine load, etc.
One of 41-43 is driven to the right or left to achieve the optimum shift.

Now, when the hydraulic pressure switching valve 36 is excited, the pressure oil of the hydraulic pressure source 12 is sent to the end chamber 57 via the passage 22 and the electromagnetic switching valve 36, and the small diameter piston 59 pushes the shift rod 56 to the left to move the first speed. The meshing of the gears of the stages is achieved. At the same time, the pressure oil in the passage 22 enters the malfunction prevention valve 71 through the electromagnetic switching valve 36, exerts pressure on the right end surface of the stepped piston 77 through the port 79, the through hole 80 of the stepped piston 77. The stepped piston 77 is pushed to the left against the force of the spring 78, and the annular groove 75 connects the port 74 with the port 76. Ports 76,7 where the oils in end chamber 63 are connected to each other
4, the electromagnetic switching valve 35 in the demagnetized state, the tank 1 through the passage 21
Returned to 7.

When the electromagnetic switching valves 35 and 36 are excited, the hydraulic power source 12
The pressure oil is sent to the end chamber 57 via the passage 22 and the electromagnetic switching valve 36, and as described above, it operates the malfunction prevention valve 71 to connect the ports 74 and 76. The pressure oil in the passage 22 is the electromagnetic switching valve 35,
It is sent to the end chamber 63 through the mutually connected ports 74 and 76 of the malfunction prevention valve 71. Therefore, the hydraulic pressure acting on the large-diameter piston 61 and the intermediate piston 60 overcomes the hydraulic pressure acting on the small-diameter piston 59, the shift rod 56 is pushed to the right, and the large-diameter piston 61 is pushed to the inner end wall of the large-diameter cylinder 62. When it hits it, it stops and is set to the neutral position.

If the energizing circuit of the solenoid operated directional control valve 36 is cut off due to a failure while the shift rod 56 is returning to the neutral position, the end chamber
57 is connected to the tank 17 via the electromagnetic switching valve 36 and the passage 21, but at this time, the stepped piston of the malfunction prevention valve 71 is connected.
77 is pushed to the right by spring 78 as shown and port 74
And 76 are shut off, the pressure oil in the passage 22 is not supplied to the end chamber 63 even if the electromagnetic switching valve 35 is excited. Therefore, it is possible to prevent the shift rod 56 from shifting past the neutral position and shifting to the reverse gear.

If the solenoid directional control valve 36 or the energizing circuits of all the electromagnetic directional control valves fail, the selector lever moves the spool 2 to the R range in which the recess 7 on the right side engages with the ball 6 of the detent mechanism 5, and the hydraulic pressure is changed. Port 8 connected to source 12
Is blocked from the port 15, and the port 18 is connected to the port 19 by the annular groove 11. Accordingly, the pressure oil is directly sent to the end chamber 63 of the hydraulic actuator 43 through the passage 26, and the shift rod 56 is shifted to the reverse gear. At this time, the oil in the end chamber 57 is returned to the tank 17 via the electromagnetic switching valve 36 and the passage 21.

Further, when the selector lever is set to the N range, both end chambers 63 and 57 of all the hydraulic actuators 41 to 43 are connected to the tank 17, and any shift rods 54 to 56 can be manually operated.

[Advantages of the Invention] As described above, the present invention provides a shift rod that achieves gear meshing between a reverse gear and a predetermined forward gear, a three-position hydraulic actuator connected to the shift rod, a hydraulic power source, and D, N, R inserted and connected to the hydraulic actuator
A hydraulic switching valve for switching to the range, a first electromagnetic switching valve inserted and connected between the hydraulic source and one end chamber of the hydraulic actuator, for shifting the shift rod to a predetermined forward stage, the hydraulic source and the hydraulic actuator. A second electromagnetic switching valve that is inserted and connected to the other end chamber of the hydraulic actuator and that shifts the shift rod to the reverse stage, and between the second electromagnetic switching valve and the other end chamber of the hydraulic actuator. Since the normally-closed type malfunction prevention valve opened by being pushed by the hydraulic pressure from the first electromagnetic switching valve to one end chamber is inserted and connected, the following effects can be obtained.

Unless pressure oil is supplied to one end chamber of the hydraulic actuator via the first electromagnetic switching valve, pressure oil is not supplied to the other end chamber even if the hydraulic source is connected to the second electromagnetic switching valve, and When the pressure oil is supplied to the other end chamber, the pressure oil is always supplied to the one end chamber, so that the piston of the hydraulic actuator stops at the neutral position, and the piston does not go too far to the reverse stage.

In other words, unless both solenoid changeover valves are normal (both solenoid changeover valves are energized and not switched), the shift rod does not return to the predetermined gear position or neutral position, and the electromagnetic circuit due to the failure of the energizing circuit The shift rod is not shifted beyond the neutral position to the reverse gear stage due to a malfunction of the switching valve (only one electromagnetic switching valve is excited and switched).

[Brief description of drawings]

FIG. 1 is a configuration diagram of a hydraulic control device for an automatic transmission according to the present invention, and FIG. 2 is a side sectional configuration diagram for explaining the operation of a hydraulic switching valve in the hydraulic control device. A: Hydraulic switching valve, B: Hydraulic control circuit, C: Hydraulic actuator, 2: Spool, 5: Day tent mechanism, 8, 15, 19: Port,
9, 11: Annular groove, 17: Tank, 21, 22: Passage, 31-36: Electromagnetic switching valve, 41-43: Hydraulic actuator, 56: Reverse / forward shift rod

Claims (1)

[Claims] 1. A shift rod for achieving meshing of gears between a reverse gear and a predetermined forward gear, and 3 connected to the shift rod.
Positionally operated hydraulic actuator, inserted between the hydraulic source and the hydraulic actuator, and connected between the hydraulic switching valve for switching to the D, N, R range, and inserted between the hydraulic source and one end chamber of the hydraulic actuator. A second electromagnetic switching valve that is connected and is inserted and connected between the first electromagnetic switching valve that shifts the shift rod to a predetermined forward stage and the hydraulic source and the other end chamber of the hydraulic actuator, and that shifts the shift rod to the reverse stage. A normally-closed malfunction that is composed of a switching valve and is opened between the second electromagnetic switching valve and the other end chamber of the hydraulic actuator by being pushed by the hydraulic pressure from the first electromagnetic switching valve toward the one end chamber. A hydraulic control device for an automatic transmission, characterized in that a prevention valve is inserted and connected.