JP2729814B2 - Hydraulic control device for automatic transmission - Google Patents

Description

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

2. Description of the Related Art Generally, an automatic transmission mounted on an automobile combines a torque converter and a transmission gear mechanism, and selectively transmits a power transmission path of the transmission gear mechanism to a plurality of frictional engagement elements such as clutches and brakes. To automatically shift to a predetermined gear. here,
As the plurality of frictional engagement elements, there are four clutches of a reverse clutch, a forward clutch, a coast clutch, and a 3-4 clutch, and two brakes of a 2-4 brake and a low reverse brake. Two one-way clutches are provided, and by changing the combination of these frictional engagement elements and one-way clutches, predetermined gear positions in a drive range (D range), two ranges, one range, and a reverse range (R range) are provided. Is obtained.

This type of automatic transmission is provided with a hydraulic control circuit for controlling the supply and discharge of hydraulic pressure to and from the actuator of each of the friction engagement elements. The hydraulic control circuit is configured to adjust the discharge pressure of the oil pump to a predetermined line pressure, a manual valve that switches the range by manual operation, and operate in accordance with the operation state to communicate with the actuators of the friction engagement elements. It is composed of a plurality of shift valves for selectively operating a plurality of frictional engagement elements by switching an oil passage, and various valves for performing other auxiliary functions.

Such a hydraulic control circuit is disclosed in, for example,
In the hydraulic control circuit disclosed in Japanese Patent Application Publication No. 246652, the shift control is adapted to the operating state by driving the shift valve by a solenoid valve, and the shift control is performed with higher accuracy.

[Problems to be Solved by the Invention] In an automatic transmission, when the hydraulic pressure is discharged from the frictional engagement element during shifting to switch from the engaged state to the released state,
It is desirable to change the discharge speed of the hydraulic pressure according to the type of shift. For example, consider a 3-4 clutch as a frictional engagement element and a 3 → 2 downshift and a 4 → 2 downshift. First, at the time of 3 → 2 downshift, the one-way clutch remains locked, so even if the hydraulic pressure of the 3-4 clutch is quickly discharged,
There is no effect on the one-way clutch. On the other hand, 4 →
At the time of the two-shift downshift, the one-way clutch changes from the free state to the locked state. Therefore, if the hydraulic pressure of the 3-4 clutch is rapidly discharged, the one-way clutch is locked rapidly, and a shift shock is generated.

Therefore, at the time of 3 → 2 downshifting, the hydraulic pressure of the 3-4 clutch is quickly discharged to shorten the shifting time, while
At the time of 4 → 2 downshifting, it is desired to gradually release the hydraulic pressure of the 3-4 clutch to gently lock the one-way clutch to prevent shift shock.

An object of the present invention is to provide a hydraulic control device for an automatic transmission that can discharge hydraulic pressure from a friction engagement element at an appropriate speed according to the type of shift.

Means for Solving the Problems The present invention relates to a transmission gear mechanism, a transmission gear mechanism, a plurality of friction fastening elements for switching a power transmission path of the transmission gear mechanism, and a plurality of oils respectively communicating with these friction fastening elements. And a hydraulic control circuit provided with a passage, wherein the control device of the automatic transmission is configured to change the speed by switching each of the oil passages. A specific frictional engagement element for releasing a hydraulic pressure to change from an engaged state to an open state when shifting to the second shift speed and during shifting from the third shift speed to the second shift speed, and A one-way clutch is provided in the power transmission path of the mechanism, and the one-way clutch is free when the hydraulic pressure of the specific frictional engagement element is discharged during the shift from the first gear to the second gear. While the state is changed from the state to the locked state, the state change is not caused when shifting from the third speed to the second speed, and the second speed is changed from the first speed to the second speed. Control for controlling the discharge speed of the hydraulic pressure of the specific friction engagement element at the time of shifting to the second shift speed to be smaller than the change speed at the time of shifting from the third shift speed to the second shift speed. Means are provided.

In a preferred aspect, the control means changes the hydraulic discharge speed of the specific frictional engagement element at the time of shifting from the first speed to the second speed by an initial change before the one-way clutch is locked. Control is performed so that the subsequent change speed is smaller than the speed.

Therefore, it is possible to achieve both the reduction of the shift shock due to the lock of the one-way clutch and the improvement of the durability of the friction engagement element.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

First, FIG. 1 shows a mechanical configuration of the automatic transmission.

In FIG. 1, an automatic transmission 10 has a torque converter
And a transmission gear mechanism 30 driven by the output of the converter 20. The mechanism 30 includes a plurality of friction fastening elements 41 to 46 such as clutches and brakes for switching power transmission paths.
And one-way clutches 51 and 52 are provided, so that the ranges D, 2, 1 and R as the driving range, the first to fourth speeds in the D range, the first to third speeds in the two range,
One or two speeds in one range can be obtained.

The torque converter 20 includes a pump 22 fixed in a case 21 connected to the engine output shaft 1,
And a one-way clutch interposed between the pump 22 and the turbine 23 and connected to the transmission case 11.
Stator 25 which is supported via 24 and performs a torque increasing action
And a lock-up clutch 26 provided between the case 21 and the turbine 23 and directly connecting the engine output shaft 1 and the turbine 23 via the case 21. The rotation of the turbine 23 is output to the transmission gear mechanism 30 via the turbine shaft 27.
Here, the pump shaft 12 penetrating through the inside of the turbine shaft 27 is connected to the engine output shaft 1.
Thus, the oil pump 13 provided at the rear end of the transmission is driven.

The transmission gear mechanism 30 is constituted by a Ravigneaux type planetary gear device. That is, the mechanism 30 includes a small-diameter small sun gear 31 loosely fitted on the turbine shaft 27.
A large-diameter large sun gear 32 also loosely fitted on the turbine shaft 27 behind the sun gear 31, a plurality of short pinion gears 33 meshed with the small sun gear 31, and a front half portion of the short pinion gear 33. The long pinion gear 34 meshed with the rear half portion meshed with the large sun gear 32, the carrier 35 rotatably supporting the long pinion gear 34 and the short pinion gear 33, and the front half portion of the long pinion gear 34 And a ring gear 36.

A forward clutch 41 and a first one-way clutch 51 are interposed between the turbine shaft 27 and the small sun gear 31 in series.
A coast clutch 42 is provided in parallel with 51. A reverse clutch 44 is interposed between the turbine shaft 27 and the large sun gear 32. Further, between the large sun gear 32 and the reverse clutch 44, the large sun gear 32 is fixed and a band brake is provided. -4 brake 45 is provided. A 3-4 clutch 43 is interposed between the turbine shaft 27 and the carrier 35.
A second one-way clutch 52 for receiving a reaction force of the carrier 35 between the carrier 35 of the 43 and the transmission case 11;
A low reverse brake 46 for fixing the carrier 35 is provided in parallel. The ring gear 36 is connected to the output gear 14, and rotation is transmitted from the output gear 14 to left and right wheels (not shown) via a differential device.

Next, the frictional engagement elements 41 such as the above clutches and brakes
The relationship between the operating state of the one-way clutches 46 and 46 and the one-way clutches 51 and 52 and the shift speed will be described.

First, in the first speed, the forward clutch 41 is engaged, and the first and second one-way clutches 51 and 52 are locked. For this reason, the output rotation of the torque converter 20 is transmitted from the turbine shaft 27 to the forward clutch.
It is input to the small sun gear 31 of the planetary gear device 30 via the 41 and the first one-way clutch 51. In this case, since the carrier 35 is fixed by the action of the second one-way clutch 52, the planetary gear device 30 performs a differential operation of transmitting rotation from the small sun gear 31 to the ring gear 36 via the short pinion gear 33 and the long pinion gear 34. It operates as a fixed gear train that does not perform As a result, a first speed state with a large reduction ratio corresponding to the diameter ratio between the small sun gear 31 and the ring gear 36 is obtained.

Next, in the second speed, the forward clutch 41 is engaged, the first one-way clutch 51 is locked,
In addition, the 2-4 brake 45 is engaged, the large sun gear 32 in the planetary gear device 30 is fixed, and the second one-way clutch 52 is idle. For this reason,
The rotation transmitted from the turbine shaft 27 to the small sun gear 31 is transmitted to the long pinion gear 34 via the short pinion gear 33, and the long pinion gear
Since the large sun gear 32 meshing with the gear 34 is fixed, the orbit 34 revolves on the large sun gear 32, and the carrier 35 rotates accordingly. As a result, compared to the first speed state, only the rotation of the carrier 35 (revolution of the long pinion gear 34)
The rotation of the ring gear 36 is accelerated, and a second speed state in which the reduction ratio is smaller than that in the first speed is obtained.

Further, in the third speed, the 2-4 brake 45 is released from the second speed state, and at the same time, the 3-4 clutch 43 is engaged. Therefore, the rotation of the turbine shaft 27 is input to the small sun gear 31 via the forward clutch 41 and the first one-way clutch 51, and is also input to the carrier 35 via the 3-4 clutch 43. .
As a result, the entire planetary gear device 30 rotates integrally,
A third speed state in which the ring gear 36 rotates at the same speed as the turbine shaft 27 is obtained.

Further, at the fourth speed, the 2-4 brake 45 once released at the third speed is engaged again. For this reason, the rotation of the turbine shaft 27 is input from the 3-4 clutch 43 to the carrier 35 of the planetary gear device 30 and the long pinion gear 34 revolves, but the large sun gear 32 meshed with the long pinion gear 34 2-4 brake
Long pinion gear 34 because it is fixed by 45
Will rotate while revolving with the carrier 35. As a result, the ring gear 36 meshing with the long pinion gear 34 is rotated at a speed corresponding to the rotation of the carrier 35 (rotation of the turbine shaft 27) by the rotation of the long pinion gear 34. Fourth gear is obtained. In this case, although the forward clutch 41 is in the engaged state, the first clutch
One-way clutch 51 is in an idling state, and coast clutch 42 is not engaged, so that rotation of turbine shaft 27 is not input to small sun gear 31.

Further, at the reverse speed, the reverse clutch 44 and the low reverse brake 46 are engaged, so that the rotation of the turbine shaft 27 is controlled by the large sun gear of the planetary gear device 30.
At the same time, the carrier 35 of the gear device 30 is fixed. Therefore, the rotation is transmitted through a fixed gear train from the large sun gear 32 to the ring gear 36 via the long pinion gear 34, and the large sun gear
A reduction ratio corresponding to the ratio of the diameter of the ring gear 36 to that of the ring gear 36 is obtained. In this case, since the rotation direction of the ring gear 36 is opposite to the rotation direction of the turbine shaft 27 and the large sun gear 32, a retreat state is obtained.

The first one-way clutch 51 that transmits the rotation at the first to third speeds and the second one-way clutch 52 that receives the reaction force at the first speed idle during idling, so that the engine brake does not operate at these speeds. Become. However, D range 3 speed, 2 range 2, 3
In the first speed and the first and second speeds in the first range, the coast clutch 42 in parallel with the first one-way clutch 51 is engaged.
At the first speed in one range, the low reverse brake 46 in parallel with the second one-way clutch 52 is engaged, so that engine braking can be obtained at these shift speeds.

Each of the above hydraulic fastening elements 41 to 46 and one-way clutch
Table 1 summarizes the relationship between the operations of 51 and 52 and the speeds.

Next, FIG. 2 shows a hydraulic control circuit 60 for supplying and discharging the hydraulic pressure to and from the actuators of the frictional engagement elements 41 to 46.

In FIG. 2, among the actuators, a hydraulic actuator 45 'of the 2-4 brake 45 is provided with an apply port.
It comprises a servo piston having a release port 45a 'and a release port 45b'. When the hydraulic pressure is supplied only to the apply port 45a ', the 2-4 brake 45 is engaged. On the other hand, when the hydraulic pressure is not supplied to both the ports 45a' and 45b 'and when the hydraulic pressure is supplied to both the ports 45a' and 45b. 2 ', the 2-4 brake 45 is released when hydraulic pressure is supplied. Also, other friction fastening elements 41 to 44,
The actuator 46 is constituted by a normal hydraulic piston, and is adapted to engage the frictional engagement element when hydraulic pressure is supplied.

The hydraulic control circuit 60 includes, as main components, a regulator valve 61 that adjusts the pressure of the hydraulic oil discharged from the oil pump 13 (see also FIG. 1) to the main line 110 to a predetermined run pressure, and a manual operation. Manual valve 62 for selecting a range according to the speed, and 1-2, 2-3, and 3-4 shifts for operating and supplying hydraulic pressure to and from each of the friction engagement elements (actuators) 41 to 46 in accordance with the shift speed. valve
63, 64, and 65 are provided.

The manual valve 62 has an input port e into which line pressure is introduced from the main line 110, and first to fourth
It has output ports ad, and the input port e is moved to the first and second positions in the D range and the second range by the movement of the spool 62a.
To the second output ports a and b, to the first and third output ports a and c in one range, and to the fourth output port d in the R range
Are connected to each other. The first to fourth output lines are respectively connected to the output ports a to d.
111 to 114 are connected.

Also, 1-2, 2-3, 3-4 shift valves 63, 64,
65 has a structure in which its spools 63a, 64a, 65a are urged rightward in the drawing by springs (not shown), and pilot ports 63b, 64b are provided on the right side of these spools 63a, 64a, 65a. , 65b are provided. The first pilot line 115 led from the main line 110 is connected to the pilot port 63b of the 1-2 shift valve 63, and the 2-3, 3-4 shift valves 64, 65
The pilot ports 64b and 65b of the first and second output ports 111 and 112, respectively, are branched from the first output line 111 through the line 116, respectively.
Pilot lines 117 and 118 are connected respectively,
These pilot lines 115, 117, 118 are provided with first, second, and third solenoid valves 66, 67, 68, respectively. When these solenoid valves 66 to 68 are in the ON state, respectively, pilot lines 115, 117, and 11
By draining 8 and discharging the pilot pressure in the pilot ports 63b to 65b of the corresponding shift valves 63 to 65, the spools 63a to 65a are positioned on the right side in the drawing. On the other hand, the solenoid valves 66 to 68
In this state, pilot pressure is introduced into the pilot ports 63b to 65b from the pilot lines 115, 117, and 118, and the spools 63a to 65a are respectively positioned on the left side in the drawing.

Here, based on a signal from the control circuit, these solenoid valves 66 to 68 are controlled based on a map set in advance according to the vehicle speed of the automobile and the throttle opening of the engine.
It is configured to be operated N, OFF. With the ON / OFF operations of the solenoid valves 66 to 68, the positions of the spools 63a to 65a of the shift valves 63 to 65 are switched, and the oil passages leading to the frictional engagement elements 41 to 46 are switched. As a result, the friction engagement elements 41 to 46 are engaged in the combinations shown in Table 1 so that the shift speed can be switched according to the operation state. In this case, the relationship between each shift speed and the combination pattern of the ON / OFF state of each of the solenoid valves 66 to 68 is set as shown in Table 2. In addition, at the time of the 3-2 downshift, the vehicle passes through an intermediate pattern shown in the same table.

Next, among the first to fourth output lines 111 to 114 connected to the respective output ports a to d of the manual valve 62, the first to fourth output lines 111 to 114 connected to the main line 110 in each of the forward ranges D, 2, and 1 are provided. From one output line 111, a line 116 is branched, and this line 116 is used as a forward clutch line, and is led to the forward clutch 41 via the one-way orifice 71. Therefore, it is understood that the forward clutch 41 is always engaged in the D, 2, and 1 ranges. Here, the forward clutch line 116
An N-D accumulator 72 for buffering when the forward clutch is engaged is connected via a line 119.

The first output line 111 is connected to the 1-2 shift valve 63.
When the first solenoid valve 66 is turned on and the spool 63a is located on the right side, the first output line 111 communicates with the servo apply line 120, and through the one-way orifice 73, It reaches the apply port 45a 'of the servo piston 45'. Therefore, when the first solenoid valve 66 is in the ON state in the D, 2, and 1 ranges,
2nd, 3rd, 4th speed in range, 2nd, 3rd speed and 1 range
In the second speed range, hydraulic pressure (servo apply pressure) is introduced to the apply port 45a ', and at this time, the release port
If no hydraulic pressure (servo release pressure) is introduced to 45b ', the 2-4 brake 45 is engaged.
In addition, a 1-2 accumulator 74 for buffering when the 2-4 brake is engaged is connected to the servo apply line 120.

Further, a second output line 112 communicating with the main line 110 in D and 2 ranges is led to the 2-3 shift valve 64. In this line 112, the second solenoid valve 67 is turned off.
In this state, when the spool 64a is located on the left side, the 3-4 clutch line is connected via the one-way orifice 75.
It is designed to communicate with 121. This line 121
Further reaches the 3-4 clutch 43 via the one-way orifice 76. Therefore, when the second solenoid valve 67 is in the OFF state in the D range, that is, when the third solenoid valve 67 is in the D range,
In the third speed of two speeds, the 3-4 clutch 43 is engaged.

Here, first and second drain lines 122 and 123 are branched from the 3-4 clutch line 121, and the first and second drain lines 122 and 123
The drain line 122 is led to the 3-4 shift valve 65,
When the third solenoid valve 68 is in the OFF state (the spool 65a is on the left side), it communicates with the line 124 and communicates with the drain port of the 2-3 shift valve 64. The second drain line 123 has a one-way orifice 77 and a fixed orifice 78.
And via one-way orifice 79, also 3-4
Guided by the shift valve 65, the third solenoid valve 68 is turned on
In the state (the spool 65a is on the right side), it communicates with the line 124 and communicates with the drain port of the 2-3 shift valve 64.

That is, during the 3-2, 4-2 downshifting in which the hydraulic pressure (3-4 clutch pressure) is discharged from the 3-4 clutch 43, the intermediate pattern in which the third solenoid valve 68 shown in Table 2 is OFF is shown. During 3-2 downshifting, the 3-4 clutch pressure is discharged by the first drain line 122, and at the 4-2 downshifting when the third solenoid valve 68 is kept ON, the second drain line
With 123, the 3-4 clutch pressure is discharged. In addition, between the one-way orifice 77 and the fixed orifice 78 of the second drain line 123, a 2-3 accumulator 80 for buffering when the 3-4 clutch is operated is connected.

Also, a line 125 connected to the first drain line 122
Like the 3-4 clutch line 121, when the second solenoid valve 67 is in the OFF state and the spool 64a of the 2-3 shift valve 64 is located on the left side, it communicates with the second output line 112. I have. This line 125 is led to the 3-4 shift valve 65, and the third solenoid valve 68 is turned off.
When the spool 65a is located on the left side in this state, it communicates with the servo release line 126. This line 126 reaches the release port 45b 'of the servo piston 45' via the one-way orifices 81, 82. Therefore, when the second and third solenoid valves 67 and 68 are both OFF in the D and 2 ranges, that is, in the 3rd speed of the D range and the 3rd speed of the 2 range,
The servo release pressure is introduced into the release port 45b 'of the servo piston 45', and the 2-4 brake 45 is released.

Further, a line 127 branched from between the two one-way orifices 81 and 82 of the servo release line 126 is provided with a coast control valve 83 and a one-way orifice 8.
4, and through the ball valve 85 to the coast clutch line 128 to reach the coast clutch 42.
Accordingly, the coast clutch 42 is engaged at the third speed in the D range and the third speed in the second range in which hydraulic pressure is introduced into the servo release line 126.

On the other hand, when the third solenoid valve 68 is OFF, the spool 65a of the 3-4 shift valve 65 is located on the left side, and when the second solenoid valve 67 is ON, the spool 64a of the 2-3 shift valve 64 is on the right side. , The forward clutch line 116 has its branch line 129, 3-4
Shift valve 65, line 130 and 2-3 shift valve 64
Through the line 131. This line 131 is further connected to the coast clutch line 128 via the ball valve 85.
Leads to. Therefore, the coast clutch 42 operates when the second solenoid valve 67 is in the ON state and the third solenoid valve 68 is in the OFF state, that is, when the second speed in the two ranges and the first
It is also engaged in the first and second speeds of the range.

Further, a third output line 113 communicating with the main line 110 in one range by the manual valve 62 is led to a 1-2 shift valve 63 via a low reducing valve 86 as a pressure reducing valve and a line 132. And
This line 132 communicates with the low reverse brake line 133 via the one-way orifice 87 and the ball valve 88 and reaches the low reverse brake 46 when the first solenoid valve 66 is OFF and the spool 63a is located on the left side. . Therefore, the first solenoid valve 66 is turned off in one range.
In the F state, that is, at the first speed in one range, the low reverse brake 46 is engaged.

Further, a fourth output line 114 communicating with the main line 110 in the R range is a line 13 branched from the line 114.
4. It communicates with the low reverse brake line 133 via the one-way orifice 89 and the ball valve 88. Further, the fourth output line 114 is connected to the reverse clutch line 135
As a result, the vehicle reaches the reverse clutch 44 via the one-way orifice 90. Therefore, in the R range, the low reverse brake 46 and the reverse clutch 44 are always engaged.
The reverse clutch line 135 is connected to an NR accumulator 91 for buffering when the reverse clutch is engaged.

Further, the hydraulic control circuit 60 is provided with a lock-up shift valve 92 for operating the lock-up clutch 26 in the torque converter 20 shown in FIG.
A torque converter line 136 from the regulator valve 61 is guided to the valve 92, and a pilot line 137 is connected to a pilot port 92b provided at one end of the valve 92. A hydraulic pressure which is branched from the line 110 and reduced in pressure by the solenoid reducing valve 93 is introduced.

A fourth solenoid valve 94 for lock-up is provided on this line 137, and when the valve 94 is in the OFF state, the spool 92a is located on the right side, so that the torque converter line 136 The internal pressure of the torque converter 20 is increased and the lock-up clutch 26 is engaged. When the solenoid valve 94 is turned on and the spool 92a moves to the left, the torque converter line 136 communicates with the lock-up release line 139 via the lock-up control valve 92 ', and locks in the torque converter 20. An up-release pressure is introduced to release the lock-up clutch 26.

The hydraulic control circuit 60 includes a regulator valve.
For controlling the line pressure adjusted by 61, a throttle modulator valve 95, a duty solenoid valve 96 for operating the valve, and a cutback valve 97
Is provided.

A line 140 branched from a line 137 leading to the main line 110 through a solenoid reducing valve 93 is guided to the throttle modulator valve 95, and a duty solenoid valve that opens and closes periodically.
The pilot pressure adjusted by the valve 96 is introduced to one end of the spool 95a, and generates a throttle modulator pressure corresponding to the duty ratio of the duty solenoid valve 96 (valve opening time ratio in one cycle). ing. In this case, the duty ratio is set according to the throttle opening of the engine, and the corresponding throttle modulator pressure is introduced into the pressure increasing port 61a of the regulator valve 61 by the line 141, whereby the duty ratio is set. The line pressure adjusted by the valve 61 is increased as the throttle opening of the engine increases.

The cutback valve 97 has a line 141 for supplying the throttle modulator pressure to the regulator valve 61.
And a line 142 branched from the first line.
To third ports 97b, 97c, 97d. A pilot pressure generated when the first solenoid valve 66 is OFF is introduced into the first port 97b through a line 143, and a second solenoid valve 67 is connected to the second port 92c. The pilot pressure generated when the valve is in the OFF state is introduced via a line 144, and the third solenoid valve 6 is connected to the third port 97d.
Pilot pressure generated when 8 is OFF
5 is to be introduced through.

The spool 97a moves according to the state of introduction of these pilot pressures, and the pilot pressure is introduced only to the first port 97b (only the first solenoid valve 66 is in the OFF state). In the first speed, line 142
Is shut off, and pilot pressure is introduced into the first and third ports 97b and 97d (the first and third solenoid valves 66 and 68 are turned off.
At the first speed in one range (in the F state), the line 142 is cut off, and the pilot pressure is introduced only into the third port 97d (only the third solenoid valve 68 is in the OFF state). At the second speed in one range, the line 142 is cut off. On the other hand, except at these shift speeds, the line 142 communicates with the line 146, and the pressure reducing port 6 of the regulator valve 61 is connected.
The line pressure is reduced by introducing the throttle modulator pressure into 1b.

In addition to the above configuration, the hydraulic control circuit 60 includes, in addition to the coast control valve 83, a bypass valve 101, a 2-3 control valve 102, Further, a timing valve 103 is provided.

As described above, the coast control valve 83 has a line 127 branched from the servo release line 126 and communicating with the coast clutch line 128 via the ball valve 85.
Along with the forward clutch line
A line pressure (forward clutch pressure) is led to the other end of the spool 83a by a line 147 branched from 116. Then, when the servo release pressure introduced to one end of the spool 83a by the line 127 and the urging force of the spring (not shown) in the valve 83 overcome the line pressure from the line 147, the line 127 is connected. It has become.

Therefore, the coast clutch 42
During the 2-3 shift up shift in the D range and the 2 range where the coast clutch pressure is supplied to the clutch, the servo release pressure is sufficiently increased, that is, the 2-4 brake is applied.
After the clutch 45 is securely released, the coast clutch 42 is engaged. Therefore, the internal lock due to the simultaneous engagement of the 2-4 brake 45 and the coast clutch 42 is prevented. In addition, since the line pressure is guided to one end of the spool 83a, the line
The communication timing is changed according to the line pressure, and the correspondence between the communication timing and the servo release pressure can be appropriately set.

Also, the bypass valve 101 has a 3-4 clutch line 1
It is provided on a bypass line 148 that bypasses the one-way orifice 76 provided in 21. The hydraulic pressure (3-4 clutch pressure) downstream of the one-way orifice 76 of the 3-4 clutch line 121 is introduced to one end of the spool 101a of the bypass valve 101, is guided from the throttle modulator valve 95, and flows through the lines 149 and 150. The modulator pressure is introduced to the other end of the spool 101a of the bypass valve 101. When the 3-4 clutch pressure rises above a predetermined value and the spool 101a moves to the left, the bypass line 148 is shut off.

Accordingly, the 3-4 clutch pressure is quickly supplied by the bypass line 148 at the start of the supply, but thereafter is gradually supplied by the one-way orifice 76. 3-
The engagement timing of the four clutches 43 is adjusted.

In addition, the 2-3 control valve 102 is provided with a bypass line 151 that bypasses the one-way orifice 81 that performs a throttling operation in the hydraulic pressure supply direction on the servo release line 126.
It is provided above. At one end of the spool 102a of the valve 102, a hydraulic pressure (3-4 clutch pressure) in the 3-4 clutch line 121 is introduced, and at the center of the spool 102a, via a line 149 and a line 152, The above-described throttle modulator pressure is introduced, and further, a servo release pressure downstream of the bypass line 151 is introduced to the other end of the spool 102a.
The bypass line 151 is opened or shut off by the action of the 3-4 clutch pressure, the throttle modulator pressure, and the servo release pressure, and the servo release pressure is adjusted in response to the increase of the 3-4 clutch pressure. It has become.

On the other hand, the timing valve 103 is a first valve that bypasses the one-way orifice 73 on the servo apply line 120.
A bypass line 153, a second bypass line 154 that bypasses the one-way orifice 82 (and 81) on the servo release line 126, and a fixed orifice 78 (and one-way orifice 79) in the second drain line 123 of 3-4 clutch pressure. Third bypass line 155 to bypass
And straddling. A pilot line 157 guided from the main line 110 via a line 156 is connected to one end of the spool 103a, and the line 157 is provided with a fifth solenoid valve 104.

This timing valve 103 is connected to the fifth solenoid valve 1
04 operates the first to third bypass lines 153 and 15
4, 155 is opened and closed, and at the time of 1-2 shift up shift,
It controls the supply / discharge timing of the hydraulic pressure at the time of the 3-2 downshift and at the time of the 4-2 downshift. Hereinafter, a specific operation of the timing valve 103 at each shift will be described.

First, at the time of the 1-2 shift-up shift, the spool 63a of the 1-2 shift valve 63 moves from the left to the right by switching the first solenoid valve 66 from the OFF state to the ON state. When the first output line 111 communicates with the servo apply line 120, the servo apply pressure is supplied to the apply port 45a 'of the servo piston 45' through the one-way orifice 73, whereby the 2-4 brake 45 Will be concluded.

During this shifting operation, the fifth solenoid valve 104 for timing valve operation is first switched from the OFF state to the ON state at the start of shifting. Therefore, the timing valve 10
The third spool 103a moves to the right, and the first bypass line 153 that bypasses the one-way orifice 73 communicates. Therefore, in the first half of the shifting operation, the servo apply pressure is quickly supplied to the apply port 45a '.

Then, when a predetermined time has elapsed from the start of the shift during the shift, the fifth solenoid valve 104 is turned ON from the ON state.
By switching to the FF state, the spool 103a of the timing valve 103 moves to the left and the first bypass line
Cut off 153. Therefore, in the latter half of the speed change operation, the servo apply pressure is gently supplied to the apply port 45a 'of the servo piston 45' via the one-way orifice 73.

Thus, at the time of the 1-2 shift-up shift, the servo apply pressure changes differently in the first half and the second half of the shift operation.
Since the bypass line 153 communicates, the moving time of the piston is shortened, the time lag of the shift-up operation is reduced, and in the latter half of the shift operation, the one-way orifice 73 and the 1-2 accumulator 74 operate smoothly. Upshifting will be realized.

Next, at the time of the 3-2 downshift in the D range, both the second and third solenoid valves 67 and 68 are turned off before the start of the shift operation and turned on after the completion of the shift operation. However, during gear shifting, the second solenoid valve 67 is turned on, and the third solenoid valve 68 is turned off.
Therefore, during shifting, the spool 64 of the 2-3 shift valve 64
a is located on the right side and the spool 65a of the 3-4 shift valve 65
Is located on the left side. Therefore, the servo release pressure supplied to the release port 45b 'of the servo piston 45' is changed to the line 126, the one-way orifices 82, 8
It is discharged from the drain port 64c of the 2-3 shift valve 64 via the 1, 3-4 shift valve 65, the line 125 and the one-way orifice 75.

During this shift, the fifth solenoid valve 104
As in the case of the above-mentioned 1-2 shift-up shift, at the start of the shift, first, the state is switched from the OFF state to the ON state, and after a predetermined time has elapsed, the state is switched to the OFF state. Accordingly, the spool 103a of the timing valve 103 first moves to the right to open the second bypass line 154, and then moves to the left to shut off the second bypass line 154. For this reason,
The servo release pressure is quickly discharged through the second bypass line 154 in the first half of the speed change operation, and is gradually discharged in the second half by the one-way orifice 82 that performs a throttle action in the discharge direction on the line 126. A fixed orifice 105 is also provided in the second bypass line 154, and this orifice 105 is
The diameter is set to be sufficiently larger than 2.

Here, at the time of this 3-2 downshift, 3-4
3-4 clutch pressure is discharged from the clutch 43. In this case, as described above, since the third solenoid valve 68 is in the OFF state and the spool 65a of the 3-4 shift valve 65 is located on the left side, the 3-4 clutch pressure is subject to the throttle action by the line 121. Through the one-way orifice 76, the second drain line 122, the 3-4 shift valve 65 and the line 124, the water is quickly discharged from the drain port 64c of the 2-3 shift valve 64.

Therefore, at the time of this 3-2 downshift, the 3-4 clutch 43 is released early, the engine speed increases rapidly, the opening time of the bypass line 154 for controlling the discharge of the servo release pressure, and the one-way orifice 82 With the setting of the diameter, the engagement of the 2-4 brake 45 can be completed at the same timing as when the engine speed stops increasing, and a fast and smooth shift can be realized.

Next, during the 4-2 downshift,
As in the case of -2 shift down, the 3-4 clutch pressure is discharged. However, in this case, the third solenoid valve
Since the 68 is held in the ON state and the spool 65a of the 3-4 shift valve 65 is held at the right position, the 3-4 clutch pressure cannot pass through the first drain line 122. Instead, the 3-4 clutch pressure is controlled by the second drain line 123 via the one-way orifice 77, fixed orifice 78, one-way orifice 79, and 3-4 shift valve.
65, and through line 124, is discharged from the drain port 64c of the 2-3 shift valve 64, in which case it will be throttled by the fixed orifice 78.

However, at the time of the 4-2 downshift, the fifth solenoid valve 104 switches from the OFF state to the ON state when a predetermined time has elapsed from the start of the shift,
The spool 103a of the timing valve 103 moves from left to right to open the third bypass line 155. Therefore, at the time of this 4-2 downshift,
The −4 clutch pressure is quickly discharged through the third bypass line 155 in the first half of the shift operation. And
In the latter half of the shifting operation, the throttle action of the fixed orifice 78 works,
Also, from the 2-3 accumulator 80 to the second drain line 12
Since the hydraulic oil is discharged to 3, the 3-4 clutch is gradually lowered.

By the way, at the time of this 4-2 downshift, the one-way clutch 51 locks from the idling state, but immediately before that, the third bypass line 155 is shut off to lock the one-way clutch 51 in a state where the hydraulic pressure is stable. As a result, a smooth shift can be realized without increasing the time lag of the shift operation.

In addition, regarding this 4-2 downshift,
The same operation as described above can be obtained by reducing the diameter of the fixed orifice 78 on the second drain line 123 without using the oil pressure holding operation of the third accumulator 80.

Also, the servo apply line 120 and the servo release line 1 provided with the orifices 73, 82 and 78, respectively.
Since the 26 and 3-4 clutch pressure second drain lines 123 perform shift operations independently of each other, the diameters of the orifices and the timing valves on the bypass lines 153, 154, and 155 that bypass these orifices are used. The operation timing and the like of 103 can be set to an optimal state without affecting other shift operations.

Next, a hydraulic control circuit according to an embodiment of the present invention will be described in detail.

FIG. 3 shows a hydraulic control circuit 60 similar to that of FIG. 2, but in FIG. 3, reference numerals are given to members necessary for describing an embodiment of the present invention. FIG. 4 is an enlarged view of a main part of FIG.

3 and 4, the line 121 of the 3-4 clutch 43 is used.
Is branched into two systems, one of the lines 121 and 122 is connected to the 3-4 shift valve 65 via a one-way orifice 76, and the other line 123 is connected to a one-way orifice 7
It is connected to a 3-4 shift valve 65 via a 7, 2-3 accumulator 80, a fixed orifice 78, and a one-way orifice 79. Here, the 3-4 shift valve 65 is
The 3-4 shift valve 65 is operated by the solenoid valve 68 and when the third solenoid valve 68 is in the OFF state.
The line 121, 122 communicates with the line 124. Conversely, when the third solenoid valve 68 is ON, the 3-4 shift valve 65 communicates the line 123 with the line 124. The line 124 communicates with the drain via the 2-3 shift valve 64.

In the above configuration, at the time of the 3 → 2 shift down shift, the third solenoid valve 68 is in the OFF state during the shift, so that the 3-4 shift valve 65 is connected to the lines 121 and 122.
Communicates with the line 124. As a result, the hydraulic pressure of the 3-4 clutch 43 is reduced to the line 121, the one-way orifice 76 not affected by the throttle action, the line 122, and the 3-4 shift valve 6
5. It is discharged from the drain port 64C of the 2-3 shift valve 64 through the line 124. In this case, since the hydraulic pressure is not subjected to the throttle action, the hydraulic pressure is discharged quickly, and the shift time is reduced. At the time of the 3 → 2 downshift, the one-way clutch 51 remains locked, so that the one-way clutch 51 is not affected even if the hydraulic pressure of the 3-4 clutch 43 is rapidly discharged.

On the other hand, at the time of the 4 → 2 downshift, the third solenoid valve 68 is in the ON state, so the 3-4 shift valve 65
Causes line 123 to communicate with line 124. This allows
The hydraulic pressures of the 3-4 clutch 43 are as follows: line 121, one-way orifice 77, line 123, fixed orifice 78, one-way orifice 79, line 123, 3-4 shift valve 65,
It is discharged from the drain port 64C of the 2-3 shift valve 64 through the line 124. In this case, the line 123 between the one-way orifice 77 and the fixed orifice 78
Since the 2-3 accumulator 80 is provided, the hydraulic pressure is gradually discharged by the hydraulic pressure holding action of the accumulator 80 and the throttle action of the fixed orifice 78 downstream of the accumulator 80.

Therefore, at the time of the 4 → 2 downshift, the hydraulic pressure of the 3-4 clutch 43 is gradually discharged, so that the one-way clutch 51 gradually changes from the free state to the locked state, thereby preventing a shift shock. Can be.

Further, in the configuration shown in FIGS.
A third bypass line 155 for bypassing the one-way orifice 78 and the one-way orifice 79 is provided.
A timing valve 103 is provided, and the timing valve 103 is operated by a fifth solenoid valve 104. That is, when the fifth solenoid valve 104 is in the ON state, the timing valve 103 is shut off to shut off the bypass line 155, and conversely, the fifth solenoid valve 1
When 04 is in the OFF state, the timing valve 103 enters the communication state, and communicates with the bypass line 155.

The operation at the time of the 4 → 2 downshift in the above configuration will be described with reference to the timing charts of FIGS. 3, 4, and 5, and the flowchart of FIG.

Beginning in step 200, in step 202, the accelerator opening x, speed V, and flag S are read. Here, the flag S
Is 1 during a 4 → 2 downshift and is 0 in other states.

If the flag S is not 1 in step 204, the process returns to step 202, but if the flag S is 1, the process proceeds to step 206.

Step 204 → 206 is to correspond to the time t ₁ of FIG. 5, the second
The solenoid valve 67 is turned on and the 3-4 clutch
43 clutch pressure begins to drain.

At this time, since the fifth solenoid valve 104 is in the OFF state, the timing valve 103 is in the communicating state and the bypass line 155 is in the communicating state. Accordingly, the hydraulic pressure of the 3-4 clutch 43 is changed to the line 121, the one-way orifice 77,
Line 123, bypass line 155, timing valve 10
3, through the bypass line 155, the line 123, the 3-4 shift valve 65, and the line 124, and is discharged from the drain port 64C of the 2-3 shift valve 64. In this case, the discharged hydraulic pressure is drained by bypassing the fixed orifice 78 and receives the hydraulic pressure holding action of the accumulator 80.
The hydraulic pressure is discharged relatively quickly without being subjected to the restricting action of the fixed orifice 78. Therefore, the shift time at the time of the 4 → 2 downshift can be shortened. In addition,
Hydraulic pressure for the state to be discharged relatively quickly, best shown at time t ₁ ~t ₂ of the timing chart of FIG. 5.

In step 208, the first
The target turbine speed N _x1 and the second target turbine speed N _x2 are obtained. Here, since N _x1 and N _x2 are functions of the vehicle speed V, they are represented by N _x1 = f (V) and N _x2 = g (V). For example, N _x1 = N _x2 × 80% Is set.

In step 210, the actual turbine speed N _T is determined, and in step 212, the actual turbine speed N _T ≧
It is determined whether or not the first target turbine speed _Nx1 is satisfied. If _NT ≧ _Nx1 , the _routine proceeds to step 214, where the fifth solenoid valve 104 is turned on.

Step 212 → 214 is to correspond to the time t ₂ of FIG. 5, a fifth
The solenoid valve 104 is turned on.

Therefore, since the timing valve 103 is in the shut-off state, the bypass line 155 is shut off. Therefore, 3-
The hydraulic pressure of the four clutch 43 passes through the line 121, the one-way orifice 77, the line 123, the fixed orifice 78, the one-way orifice 79, the line 123, the 3-4 shift valve 65, the line 124, and the drain port of the 2-3 shift valve 64. 6
Emitted from 4C. In this case, the discharged hydraulic pressure is gradually discharged by the hydraulic pressure holding action of the accumulator 80 and the throttle action of the fixed orifice 78. Therefore 4
→ During two downshifts, the one-way clutch 51
Since the state is gradually changed from the free state to the locked state, shift shock can be prevented. Incidentally, the hydraulic pressure for the condition to be gradually discharged, best shown at time t ₂ ~t ₃ in the timing chart of FIG. 5.

In step 216, the actual turbine speed N _T is determined, and in step 218, the actual turbine speed N _T ≧
It is determined whether or not the second target turbine speed _Nx2 is satisfied. If _NT ≧ _Nx2 , the _routine proceeds to step 220, where the fifth solenoid valve 104 is turned off. Then step 22
Go to 2 and return. Step 220 is the fifth step.
Corresponding to the time t ₃ of FIG.

“Effects of the Invention” As described above, according to the present invention, when shifting from the first shift speed to the third shift speed, the first branch oil passage is communicated with the drain, while the second shift speed is changed. When shifting from the first gear to the third gear, a second gear provided with an accumulator is provided.
Since the switching means for communicating the branch oil passage with the drain is provided, when shifting from the first shift stage to the third shift stage, the hydraulic pressure from the friction engagement element is drained via the first branch oil passage. , While the second gear shifts to the third gear
When the gear is shifted to the first gear, the oil pressure at the friction engagement element is slowly discharged through the second branch oil passage provided with the accumulator. Therefore, the hydraulic pressure can be discharged from the friction engagement element at an appropriate speed according to the type of shift.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a mechanical configuration of an automatic transmission, FIG. 2 is a circuit diagram of a hydraulic control circuit, and FIG. 3 is a hydraulic control circuit similar to FIG. FIG. 4 is a circuit diagram in which members necessary for explaining the example are denoted by reference numerals, FIG. 4 is a configuration diagram schematically showing necessary members in FIG. 3,
FIGS. 5 and 6 are a timing chart and a flowchart, respectively, at the time of a 4 → 2 downshift. 10 ... automatic transmission, 30 ... transmission gear mechanism, 60 ... hydraulic control circuit, 43 ... 3-4 clutch, 64 ... 2-3 shift valve, 64C ... drain port, 65 ... 3-4 Shift valve, 67… 2nd solenoid valve, 68… 3rd solenoid valve, 76 …… One-way orifice, 77 …… One-way orifice, 78 …… Fixed orifice, 79 …… One-way orifice, 80 …… 2-3 accumulator , 103: Timing valve, 104: Fifth solenoid valve, 121: Line, 123: Line, 124: Line, 155: Bypass line.

Claims (2)

(57) [Claims] 1. A hydraulic control circuit comprising: a speed change gear mechanism; a speed change gear mechanism; a plurality of friction engagement elements for switching a power transmission path of the speed change gear mechanism; and a plurality of oil paths respectively communicating with the friction engagement elements. A control device for an automatic transmission configured to shift by switching each of the oil passages, wherein the plurality of frictional engagement elements are used when shifting from a first shift speed to a second shift speed. And a specific frictional engagement element that is released from the hydraulic pressure during the shift from the third gear to the second gear and changed from the engaged state to the released state, and the power transmission path of the transmission gear mechanism includes: A one-way clutch is provided, and the one-way clutch changes from a free state to a locked state in accordance with discharge of the hydraulic pressure of the specific friction engagement element when shifting from the first gear to the second gear. On the other hand, during the shift from the third gear to the second gear, the state change is not caused, and the shift from the first gear to the second gear is performed. Control means is provided for controlling the discharge speed of the hydraulic pressure of the specific frictional engagement element at the time of shifting so as to be smaller than the changing speed at the time of shifting from the third gear to the second gear. A control device for an automatic transmission. 2. The system according to claim 1, wherein the control means controls the hydraulic discharge speed of the specific frictional engagement element at the time of shifting from the first gear to the second gear in an initial period before the one-way clutch is locked. Compared to the speed of change
The control device for an automatic transmission according to claim 1, wherein the control is performed such that a change speed thereafter becomes smaller.