JPH05586B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a hydraulic control system for an automatic transmission having a torque converter equipped with a lock-up mechanism.

[Prior art and problems to be solved by the invention]

Lock-up mechanism (mechanism that mechanically connects the pump impeller and turbine runner as necessary)
In the case of an automatic transmission having a torque converter equipped with a torque converter, it is preferable to operate the lock-up mechanism from as low a speed as possible in order to improve efficiency. Therefore, in the case of an automatic transmission with four forward speeds, for example, it is desirable to always operate the lock-up mechanism at least at the third speed or higher. However, when shifting between 3rd and 4th speeds with the lock-up mechanism activated, the torque fluctuates as the engine crankshaft and automatic transmission input shaft are mechanically connected. This causes a large shock when changing gears. For this reason, in conventional automatic transmissions, the operation of the lock-up mechanism was released only when changing gears, but in order to do so, an electronic Since it requires a control device and sensors, actuators, etc. that work together with the control device, it is very expensive. Furthermore, if the same action was performed by a hydraulic control device without using an electronic control device, the hydraulic control device would have an extremely complicated configuration.
This was not satisfactory in terms of price and required space. In order to solve such problems, the present applicant has proposed an automatic transmission having a torque converter with a lock-up mechanism in Japanese Patent Application No. 1988-3488 (filed on January 14, 1982). In this hydraulic control system (Japanese Patent Application Laid-Open No. 63-21063), the lock-up mechanism is released for a short time only during a gear shift by utilizing the time delay in the hydraulic pressure change of two friction engagement elements whose operating states change during a gear shift. A lock-up valve was disclosed. However, since this lock-up valve was designed to be switched using changes in the operating pressure of the frictional engagement element, it was not possible to always release the lock-up mechanism as desired under all speed change conditions. In other words, in general, when the oil pressure of a friction engagement element increases, it takes a relatively long time for the oil pressure to reach a predetermined value due to piston movement, etc., but when the oil pressure decreases, it takes a relatively short time. It becomes below a predetermined value. Therefore, in the former case, sufficient time can be secured to release the lock-up mechanism, but in the latter case, the release time is shortened, and in some cases, the lock-up mechanism may be re-engaged before the shift is completed. There was a fear that this would cause a large shift shock. Furthermore, Japanese Patent Application Laid-Open No. 52-109078 discloses that in the case of a device having an accumulator that alleviates changes in the oil pressure of a hydraulic cylinder for shifting, the lock-up mechanism is temporarily released using changes in the oil pressure of the hydraulic cylinder. It shows what was done to make it happen. However, in these cases, the accumulator is basically used to adjust the capacity during shifting, so if the characteristics of the accumulator are set to be appropriate for the shifting shock, it may not be consistent with the control of the release time of the lock-up mechanism. The sex is great. In particular, when discharging the hydraulic pressure from the hydraulic cylinder, the function of the accumulator is stopped and the hydraulic pressure is rapidly discharged, so as in the above example, it is not possible to secure enough time to release the lock-up mechanism. There is a high possibility that the lock-up mechanism will be re-engaged before the gear shift is completed, resulting in a large discoloration shock.

[Means to try to solve the problem]

The present invention was made by focusing on the above-mentioned problems in a hydraulic control system for an automatic transmission that has a torque converter equipped with a lock-up mechanism. An accumulator is provided in the switching pressure oil path, which is connected to the oil chamber of the frictional engagement element for speed change via an orifice.
The purpose of the present invention is to solve the above-mentioned problems by making it possible to set the switching timing of the lock-up control valve as desired, and to obtain a hydraulic control device for an automatic transmission having a torque converter equipped with a better lock-up mechanism. . That is, the hydraulic control device for an automatic transmission according to the present invention has a lock-up control valve and a lock-up timing valve, and the lock-up control valve has a lock-up mechanism that can connect or release the pump impeller and the turbine runner. The lock-up control valve can be switched between a first position where the lock-up control valve is in the open state and a second position where the lock-up control valve is in the released state. A first port (port 144a in the embodiment described later) and a second port (port 144a in the embodiment described later)
A first oil passage (oil passage 45, port 144b) which generates oil pressure at the mth speed (third speed) of the automatic transmission and does not generate oil pressure at the m+1st (fourth speed, same).
2) is connected to the first port, and the lock-up timing valve uses the oil pressure in the first oil passage as switching pressure to generate no oil pressure in the second oil passage (454) at the mth speed and at the m+1st speed. the second oil passage is connected to the second port of the lock-up control valve;
When the spool of the lock-up control valve switches between the first position and the second position, the oil pressure in the first and second oil passages is at a relatively high first value (F
1), the oil pressure in the first oil passage when the lock-up timing valve switches is the relatively low second value (F2), and during the shift operation between the mth speed and the m+1st speed. The lock-up mechanism is temporarily released, and the first oil path is connected to an accumulator (
52), and there is a bidirectional pipe between the part of the first oil passage connected to the first port and the accumulator and the oil chamber of the friction engagement element for speed change connected to the first oil passage. An orifice (660) having a throttling effect on the flow is provided, and the accumulator makes the hydraulic pressure smaller than the first hydraulic pressure when the hydraulic pressure rises and falls in the first oil passage. The predetermined time is determined by the stroke time of the piston of the accumulator and is required for a speed change operation by engaging or releasing the friction engagement element. It is characterized by being set to a length of more than an hour.

【Example】

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6 of the accompanying drawings. FIG. 1 shows a schematic diagram of a power transmission mechanism of an automatic transmission with four forward speeds and one reverse speed, which has a torque converter with a lockup mechanism. This power transmission mechanism includes an input shaft I that transmits rotational force from an engine output shaft E via a torque converter T/C, an output shaft O that transmits driving force to a final drive device,
First planetary gear set G ₁ , second planetary gear set G ₂ , first clutch C ₁ , second clutch C ₂ , third clutch C ₃ ,
It has a first brake _B2 , a second brake _B2 , and a one-way clutch OWC. The first planetary gear set G ₁ includes a sun gear S ₁ , an internal gear R ₁ ,
Pinion gear that meshes with both gears S ₁ and R ₁ at the same time
The planetary gear set _{G 2 supports} a sun gear S ₂ , an internal gear R _{2 ,} and a pinion gear P ₂ that meshes with both gears S ₂ and R ₂ simultaneously. It consists of _two carrier PCs. Carrier PC ₁ is clutch C ₂
The sun gear S ₁ can be connected to the input shaft I via a clutch C ₁ . Carrier PC ₁ can also be connected to internal gear R ₂ via clutch C ₃ . sun gear
_S2 is always connected to the input shaft I, and internal gear _R1 and carrier _PC2 are always connected to the output shaft O. Brake B ₁ can fix carrier PC ₁ , and brake B ₂ can fix sun gear S ₁ . The brake _B2 is a band brake, and is operated by the hydraulic pressure applied to the servo apply chamber S/A and the servo release chamber S/R, which has a larger operating area. In other words, when hydraulic pressure is applied to the servo apply chamber S/A, the brake B ₂ is engaged, and when hydraulic pressure is applied to the servo release chamber S/R, the brake B ₂ is released regardless of whether there is hydraulic pressure in the servo apply chamber S/A. be done. One-way clutch OWC
has a structure that allows forward rotation (rotation in the same direction as the engine output shaft E) of carrier PC ₁ , but does not allow reverse rotation (rotation in the opposite direction to forward rotation) (i.e., a structure that acts as a brake only when reverse rotation is performed). . The torque converter T/C has a pump impeller PI, a turbine runner T, a stator ST, and a lock-up clutch L. Pump impeller PI is connected to engine output shaft E via torque converter cover PI'. The turbine runner T is connected to the input shaft I, and the stator ST is connected to the stationary part via a one-way clutch SOWC. The lock-up clutch L connected to the turbine runner T is movable in the axial direction, and the torque converter cover is integrated with the pump impeller PI.
A lock-up clutch oil chamber LC is formed between the lock-up clutch oil chamber LC and the torque converter cover PI. ′ so that it rotates with it. As a specific example of this lock-up mechanism, the one described in Japanese Patent Application No. 53-38849 (Japanese Unexamined Patent Publication No. 54-132060) filed by the present applicant is used. The power transmission mechanism includes clutches C ₁ , C ₂ and C ₃ ,
Brake B ₁ (one-way clutch OWC) and B ₂
By operating the planetary gear sets G ₁ and G ₂ in various combinations, each element (S ₁ , S ₂ , R ₁ , R ₂ ,
The rotation state of PC ₁ and PC ₂ ) can be changed,
This allows the rotational speed of the output shaft O to be varied in relation to the rotational speed of the input shaft I. By operating clutches C ₁ , C ₂ and C ₃ and brakes B ₁ and B ₂ in combination as shown in the table below,
You can get 4 forward speeds and 1 reverse speed.

[Table] In the above table, the O symbol indicates the clutch and brake that are in operation, and the gear ratio is the ratio of the rotation speed of the input shaft I to the rotation speed of the output shaft O. Also,
The fact that (OWC) is displayed under B ₁ indicates that the first speed can be obtained by the one-way clutch OWC even when the brake B ₁ is not operated. However, in the first speed in this case, the output shaft O
Cannot be driven from the side (i.e. no engine braking). Further, at the bottom of the column _B2 , the state of oil pressure supply to the servo apply chamber S/A and the servo release chamber S/R is shown. Figures 2a and 2b show a hydraulic circuit of a hydraulic control device for controlling the power transmission mechanism. This hydraulic control device includes a regulator valve 2,
Manual valve 4, throttle valve 6, throttle fuel safety valve 8, throttle modulator valve 10, pressure modifier valve 12, cutback valve 14, line pressure booster valve 16, governor valve 18, 1-2
Shift valve 20, 2-3 Shift valve 22, 3
-4 shift valve 24, 2-4 timing valve 26, 2-3 timing valve 28, 3-4 timing valve 30, 3-2 timing valve 3
2. 1st speed fixed range pressure reducing valve 34, torque converter pressure reducing valve 36, 1-2 accumulator 3
8, 4-3 has an accurator 40, an overdrive inhibitor solenoid 42, a lockup control valve 44, a lockup timing valve 46, a 3rd speed speed cut valve 48, a 4th speed speed cut valve 50, and a lockup accumulator 52. These valves are connected to each other as shown in Figures 2a and 2b, and are connected to an oil pump O/P, a torque converter T/C, a lock-up clutch oil chamber LC, clutches C1, C2, and C3, and a brake. B1 and B
2 are connected as shown. The brake B2 has a servo apply chamber S/A, which is a hydraulic chamber that applies the brake, and a servo release chamber S/R, which is a hydraulic chamber that releases the brake. The area is larger than the pressure receiving area of the servo apply chamber S/A, so when hydraulic pressure is supplied to the servo release chamber S/R, brake B2 is released even if hydraulic pressure is supplied to the servo apply chamber S/A.) . With this configuration, the clutches C1, C2 and C3 and the brakes B1 and B2 operate as shown in the table above, depending on the vehicle speed and the throttle opening of the engine. In the following explanation, the parts directly related to the present invention will be mainly explained, and the detailed explanation of other parts will be omitted.
This is similar to that disclosed in No. 036606, and the names of the parts indicated by each reference numeral are listed for reference. Code 102, 104, 106, 108, 11
0,112,114,116,120,122,
124, 126, 128, 10, 132, 134
and 136 are valve holes, numerals 102a to 102a-j, 10
4a-f, 106a-f, 108a-f, 110
a~e, 112a~e, 114a~g, 116a
~f, 120a~k, 122a~j, 124a~
k, 126a-e, 130a-e, 132a-
e, 134a-e and 136a-e are ports, 138 and 140 are cylinder holes, 202,
203, 204, 206, 210, 212, 21
4,215,216,220,221,222,
224, 226, 228, 230, 232, 23
4 and 236 are spools, symbols 202a to 202d, 2
03a-b, 204a-b, 206a-c, 20
8a, 210a-c, 212a-b, 214a-
c, 215a-b, 216a-c, 220a-
c, 221a-d, 222a-e, 224a-
d, 226a-c, 228a-c, 230a-
c, 232a-c, 234a-b and 236a-
b is a land, 207 is a plunger, 20
8 is a sleeve, 209 is a plug, 223
and 225 are plugs, 238 and 240 are pistons, 252 are sleeves, and 252a~
c is a port, 254 is a spring seat, 302, 306, 307, 308, 310, 3
12,316,320,322,324,32
8, 330, 332, 334, 336, 338 and 340 are springs, symbols 402, 404 _, 4
06,408,409,410,411,41
2,414,416,418,420,422,
424, 426, 428, 430, 432, 43
4,436,438,440,442,444,
446, 448 and 450 are oil passages, code 502,
504, 506 and 508 are shuttle valves, codes 602, 604, 606, 608, 610, 6
12,614 _, 616 _, 618 _, 620 _, 62
2,624,626,628,630,650,
652, 654, 656 and 658 are orifices, codes 750, 752, 754, 756 and 7
Reference numeral 58 indicates a check valve. The following description will be made mainly based on FIG. 2b. The lock-up control valve 44 has a spool 244 inserted into the valve hole 144 so as to be movable in the axial direction, and a spring 344 that pushes the spool 244 to the left in the figure. The valve hole 144 has ports 144a, 144b, 144c,
144d, 144e, 144f and 144g, and the spool 244 has lands 244a, 2
44b, 244c and 244d (land 244b
and 244c have the same diameter, lands 244a and 244
d has a smaller diameter than these. port 14
4a is connected to the oil passage 452, and the port 14
4b is connected to the oil passage 454, and the port 14
4c communicates with an oil passage 450 that supplies pressure oil from the regulator valve 1 to the torque converter T/C, and the port 144d communicates with the lock-up clutch oil chamber LC via an oil passage 456. 144e and 144g are drain ports, and the port 144f is connected to an oil passage 412 to which line pressure is supplied during forward movement. The lock-up timing valve 46 includes a spool 246 inserted into the valve hole 146 so as to be movable in the axial direction;
Spring 3 that pushes the spool 246 to the left in the diagram
46. Valve hole 146 is port 1
46a, 146b, 146c, 146d and 14
6e, and the spool 246 is connected to the land 24.
6a and 246b (lands 246a and 246b have the same diameter). Port 146a is oil path 4
52, and the port 146b is connected to the oil passage 45.
The port 146c communicates with the port 144b of the lockup control valve 44 via an oil passage 454, and the port 146c communicates with the port 144b of the lockup control valve 44 via an oil passage 454.
6d and 146e are drain ports. The 3rd speed speed cut valve 48 is located in the valve hole 1.
The spool 248 has a spool 248 inserted into the spool 48 so as to be movable in the axial direction, and a spring 348 that pushes the spool 248 to the left in the figure. Valve hole 148
has ports 148a-148e. The ports 148b and 148e are drain ports, the port 148a is supplied with governor pressure, which is oil pressure corresponding to the vehicle speed, from the oil passage 430, and the port 148c is connected to the port 144a of the lock-up control valve 44 via the oil passage 452. , port 146a of lock-up timing valve 46
The port 146d is connected to an oil passage 444, which will be described later.
It is connected to the servo release chamber S/R via. Note that an orifice 660 is provided in the oil passage 444. The spool 248 has a land 24 of the same diameter.
8a and 248b, and the land 248a
and 248b communicate port 148c with port 148b or 148d depending on the position of spool 248. Further, the governor pressure of the port 148a acts on the left end of the land 148a in the figure. The 4th speed speed cut valve 50 has the same configuration as the 3rd speed speed cut valve 48, and includes a spool 250 inserted into the valve hole 150 so as to be movable in the axial direction.
and a spring 350 that pushes the spool 250 to the left in the figure. Valve hole 150 has ports 150a to 150e. Port 1
50b and 150e are drain ports, port 150a is connected to the aforementioned governor pressure oil passage 430, and port 150c is connected to port 1 of the lock-up timing valve 46 via oil passage 458.
46b, and the port 150d is connected to the clutch C2 via an oil passage 434.
The spool 250 has lands 250a and 2 having the same diameter.
50b. Land 250a and 250
b is port 150 depending on the position of spool 250
c is communicated with port 150b or 150d.
The governor pressure of the port 150a acts on the left end surface of the land 250a in the figure. The lock-up storage unit 52 includes a piston hole 152, a piston 252 inserted into the piston hole 152 so as to be movable in the axial direction, and a piston 252 inserted into the piston hole 152 so as to be movable in the axial direction.
52 is provided with a spring 352 that pushes downward in the figure. A chamber 152a on the lower side in the figure partitioned by the piston 252 is connected to the oil passage 452, and a chamber 152b on the upper side in the figure is drained. Torque converter supply pressure is supplied to the torque converter T/C from an oil passage 450, and oil in the torque converter T/C is discharged to an oil passage 460. The oil in the oil passage 460 is drained through the pressure holding valve 54. Torque converter T/
The lock-up oil chamber LC inside C communicates with the oil passage 456 as described above. Next, the effect will be explained. In the first speed or second speed state, no oil pressure is supplied to the clutch C2 and the servo release chamber S/R, so the oil pressure in the oil passages 434 and 444 is zero. Therefore, 3rd speed speed cut valve 4
Regardless of the state of the 8th and 4th speed speed cut valves 50, no oil pressure acts on the oil passages 458 and 452, no oil pressure acts on the port 146b of the lock-up timing valve 46, and no oil pressure acts on the spool 24.
6 is pushed by a spring 346 to the position shown in the upper half of the figure. Therefore, no oil pressure acts on the oil passage 454, no oil pressure acts on the port 144b of the lockup control valve 44, and no oil pressure acts on the port 144b of the lockup control valve 44.
spool 244 without hydraulic pressure acting on 44a.
is the force due to the spring 344 and the port 144f
It is pushed to the position shown in the upper half of the figure by the force of the hydraulic pressure acting on it. Therefore, oil passage 450 and oil passage 45
6 is in communication with the lock-up clutch LC, and the torque converter supply pressure of the oil passage 450 is supplied to the lock-up clutch LC. Therefore, the oil pressure in the lock-up clutch oil chamber LC becomes equal to the pressure inside the torque converter T/C, and the lock-up clutch L is released. As the vehicle speed increases, the 2-3 shift valve 22
When the spool is switched to the position on the left half in FIG.
and generates oil pressure in the oil passage 444. When the vehicle speed is high to a certain extent and both the 3rd speed speed cut valve 48 and the 4th speed speed cut valve 50 are in the positions shown in the lower half of the figure, the oil pressure in the oil passages 434 and 444 is supplied to oil passages 458 and 452, respectively. be done. For this reason, the lock-up control valve 4
Hydraulic pressure acts on ports 144a and 144b of No. 4, and the spool 244 is switched to the position shown in the lower half of the figure. Therefore, the port 144c communicating with the oil passage 450 is closed by the land 244b, and the oil passage 456 communicates with the drain port 144e. Since the oil in the lock-up clutch oil chamber LC is discharged to the drain port 144e through the oil passage 456 and the port 144d, the lock-up clutch L is in a fastened state. In addition, the piston 252 of the lock-up accumulator 52
has been moved upward in the figure by the hydraulic pressure acting on the oil chamber 152a from the oil passage 452. Next, when the spool of the 3-4 shift valve 24 is switched from the third speed position in the right half of FIG. 2a to the fourth speed position in the left half of the same figure, the oil pressure in the servo release chamber S/R decreases. Start. The oil pressure in the servo release chamber S/R decreases as shown in FIG. spring 3
52, it descends as shown in FIG. When the oil pressure of the oil passage 452 (that is, the oil pressure of the port 144a of the lockup control valve 44 and the port 146a of the lockup timing valve 46) decreases to _F1 , the spool 244 of the lockup control valve 44 immediately moves to the lower half in the figure. The pressure receiving area of the spool 244 and the force of the spring 344 are set so as to switch from the position to the upper half position.
Therefore, ports 144c and 144d communicate with each other, and lock-up clutch L is released. However, when the oil pressure in the oil passage 452 decreases to _F2 after _t2 hours, the spool 246 of the lockup timing valve 46 is moved from the lower half position to the upper half position by the spring 346. The pressure receiving area and the force of the spring 346 are set. Therefore ports 146b and 146c
The oil pressure in the oil passage 458 (this oil pressure is the oil pressure in the clutch C2) is introduced into the oil passage 454, and acts on the port 144b of the lock-up control valve 44, switching the spool 244 to the lower half position. , the lock-up clutch L is engaged again. Therefore, during the shift operation from the third speed to the fourth speed, the lock-up clutch L is released during the time period _t1 to _t2 shown in FIG. 4, and the occurrence of a shift shock is prevented. The lock-up clutch L is disengaged in the same manner when shifting from fourth gear to third gear. That is, when the 3-4 shift valve 24 is switched from the fourth speed position to the third speed position, the oil pressure in the servo release chamber S/R starts to rise. The oil pressure in the servo release chamber S/R rises as shown in FIG. Rise as shown in the figure. Therefore, the spool 246 of the lock-up timing valve 46 receives a force directed to the right in the figure, but the force of the spring 346 is applied to the spool 246 when the oil pressure reaches the _F2 rotation in FIG.
It is set so that the position of 6 can be switched. When spool 246 is in the lower half position, port 146
b is closed by land 246a, and port 1
46c and the drain port 146d communicate with each other, and the oil pressure in the oil passage 454 becomes zero. Therefore, the hydraulic pressure that was acting on the port 144b of the lock-up control valve 44 disappears. The oil passage 4 is also connected to the port 144a of the lock-up control valve 44.
52 oil pressure is applied, but this oil pressure does not reach F ₁ until time t ₂ ' shown in FIG. For this reason, the spool 2 of the lock-up control valve 44
44 is the force of the spring 344 and the port 144f
It is switched to the upper half position in the figure by the hydraulic force of . When spool 244 is switched to the upper half position, lockup clutch L is released as before. However, when the oil pressure exceeds the _F2 point at time _t2 ', the lock-up control valve 44
The spool 244 is again in the lower half position in the figure, and the lock-up clutch L is fastened. That is, the oil pressure at the port 144a decreases only during the time period _t1 to _t2 when the oil pressure in the oil passage 452 rises, thereby switching the lock-up control valve 44 and releasing the lock-up clutch L. Therefore, when shifting from 3rd to 4th speed, the 6th
During the time period t ₁ ' to t ₂ ' shown in the figure, the lock-up clutch L is released and the occurrence of a shift shock is prevented. Although not directly related to the present invention, the functions of the 3rd speed speed cut valve 48 and the 4th speed speed cut valve 50 will be explained here. When the vehicle speed is high and the governor pressure in the oil passage 430 is high, the 3rd speed speed cut valve 48 and the 4th speed speed cut valve 50 are both in the lower half of the figure, and the oil passages 444 and 452 and the oil passage 434 and 458 are in communication with each other, so hydraulic pressure is supplied to the lockup control valve 44 and the lockup timing valve 46 as described above. However, when the governor pressure becomes low and the 3rd speed speed cut valve 48 and the 4th speed speed cut valve 50 are in the state shown in the upper half of the figure, the oil in the oil passages 452 and 458 is drained from the drain port 148b, respectively.
As a result, the lockup control valve 44 and the lockup timing valve 46 are in the state shown in the upper half of the figure, and the lockup clutch L is released. That is, the lock-up clutch L is not engaged below a predetermined vehicle speed, and vibrations can be prevented from occurring at low speeds. The lock-up clutch L can be operated most efficiently if the forces of the springs 348 and 350 are set so that the spools 248 and 250 are switched at the limits where vibration occurs in the fourth and third speeds, respectively. can. As explained above, since the present invention has the above-described configuration, it is possible to set the release time of the lock-up mechanism during gear shifting as desired, and the lock-up mechanism is engaged during gear shifting in any driving condition. Therefore, the shift shock can be made smaller.
In particular, the accumulator is connected via an orifice to the oil chamber of the frictional engagement element for speed change, and can alleviate changes in the oil pressure at the first port independently of changes in the oil pressure in this oil chamber. Similarly, in the case of downshifting, the release time of the lockup mechanism can be set as desired regardless of changes in the oil pressure for gearshifting, and it is possible to ensure that the lockup mechanism is not engaged during gearshifting. Prevented.

[Brief explanation of drawings]

Figure 1 is a skeleton diagram of an automatic transmission, Figures 2a and 2b
The figure shows a hydraulic control device according to the present invention.
FIG. 6 is a diagram showing changes in oil pressure. 44...Lockup control valve, 4
6... Lockup timing valve, 48...
3-speed speed cut valve, 50... 4-speed speed cut valve, 52... Lock-up accumulator, T/C... Torque converter, L... Lock-up clutch, LC... Lock-up clutch oil chamber, S/ R... Servo release room.

Claims (1)

[Claims] 1. The lock-up control valve has a lock-up control valve and a lock-up timing valve, and the lock-up control valve has a first position in which the lock-up mechanism capable of connecting or releasing the pump impeller and the turbine runner is in the engaged state, and a second position in which the lock-up mechanism is in the released state. When hydraulic pressure is applied, the lock-up control valve spool can be switched between
It has a first port and a second port that bias toward the position side, and generates hydraulic pressure at the m-th speed of the automatic transmission.
A first oil passage that does not generate oil pressure at the +1 speed is connected to the first port, and the lock-up timing valve uses the oil pressure of the first oil passage as a switching pressure to generate no oil pressure in the second oil passage at the m-th speed. the second oil passage is connected to the second port of the lock-up control valve;
The oil pressures in the first and second oil passages when the spool of the lock-up control valve switches between the first position and the second position are at a relatively high first value;
The oil pressure in the first oil passage when the lock-up timing valve switches is a relatively low second value, and the lock-up mechanism is temporarily in the released state during the shift operation between the mth speed and the m+1th speed. The first oil passage has an accumulator, and a portion of the first oil passage connected to the first port and the accumulator, and an oil chamber of a friction engagement element for speed change connected to the first oil passage. An orifice having a throttling effect on the flow in both directions is provided between them, and the accumulator reduces the hydraulic pressure to be smaller than the first value of hydraulic pressure when the hydraulic pressure in the first oil passage rises and falls. ,
The predetermined time is configured to be maintained at a state greater than the second value of oil pressure for a predetermined time and is determined by the stroke time of the piston of the accumulator, and the predetermined time is determined by the speed change operation by engaging or releasing the friction engagement element. 1. A hydraulic control device for an automatic transmission having a torque converter with a lock-up mechanism, characterized in that the length is set to be longer than the time required for the lock-up mechanism.