JP3117480B2 - Control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission.

[0002]

2. Description of the Related Art Generally, an automatic transmission for an automobile is provided with a torque converter and a transmission gear mechanism. here,
The torque converter shifts the torque of the engine output shaft and transmits the torque to the turbine shaft, and the transmission gear mechanism further shifts the torque of the turbine shaft and reverses the rotation direction during reverse to transmit the torque to the drive wheels. It has become. The transmission gear mechanism usually includes a planetary gear system including a sun gear, a ring gear, a pinion gear, and a carrier. The transmission gear mechanism connects or disconnects a turbine shaft and predetermined gears.
Operating a plurality of clutches (hereinafter referred to as on / off), a plurality of brakes for fixing or releasing the predetermined gear (hereinafter referred to as on / off), and these clutches and brakes And a hydraulic mechanism. Here, the transmission gear mechanism switches the on / off pattern of each clutch and each brake by a hydraulic mechanism, thereby switching the power transmission path in the planetary gear system, and performing the shift and the forward / reverse switching. ing.

In such a speed change gear mechanism, usually, a reverse clutch and a low reverse brake are provided in order to obtain a reverse speed, and when the reverse range is selected by operating a select lever, that is, when the vehicle is moving in reverse, the reverse clutch and the low reverse brake are engaged. When the reverse brake is turned on and the select lever is shifted from the reverse range to the non-reverse range (neutral range or parking range), the reverse clutch and the low reverse brake are turned off.

FIG. 11 shows an example of a conventional hydraulic mechanism for supplying hydraulic pressure to such a reverse clutch and a low reverse brake. As shown in FIG. 11, the conventional hydraulic mechanism F
_{In 1} , when the reverse range is selected by operating a select lever (not shown), the manual valve 101 takes the reverse range position accordingly,
At this time, the hydraulic pressure (line pressure) in the line pressure supply passage 102
Is supplied to a reverse range hydraulic supply passage 103 via a manual valve 101, and the hydraulic pressure is supplied to a reverse clutch 106 and a low reverse brake 1 via a first or second branch hydraulic supply passage 104, 105, respectively.
07 and both are turned on. Thus, the automatic transmission is in the reverse drive state.

On the other hand, when shifting from the reverse range to the non-reverse range (N range or P range),
The manual valve 101 is in the non-reverse range position. At this time, the hydraulic pressure in the reverse clutch 106 and the hydraulic pressure in the low reverse brake 107 respectively correspond to the first or second branch hydraulic supply passages 104 and 105 and the reverse range hydraulic pressure. It is configured to be released from the drain port 108 via the supply passage 103 and the manual valve 101 (for example, see Japanese Patent Application Laid-Open No. 63-186055).

Here, when the reverse range is selected, if hydraulic pressure is suddenly supplied to the reverse clutch 106 and the low reverse brake 107, both are suddenly turned on, and the output torque of the transmission gear mechanism changes suddenly. Therefore, in order to prevent the occurrence of the engagement shock, an accumulator 109 is provided, for example, facing the second branch hydraulic pressure supply passage 105 and buffering the rise of the hydraulic pressure.

By the way, in the conventional hydraulic mechanism F ₁ as shown in FIG. 11, when it is shifted from the reverse range to the non-reverse range, the hydraulic pressure to the hydraulic fluid in the reverse clutch 106 (hereinafter, simply referred to as oil pressure) is little time Although released rapidly without delay, the low reverse brake 107 is normally provided with a dish plate (not shown), so the hydraulic pressure in the low reverse brake 107 is released relatively slowly. In this case, the reverse driving state of the transmission gear mechanism is released when the reverse clutch 106 is turned off, so that the release of the reverse driving force becomes very sharp. At this time, the engine mount, which has been bent by the reverse driving force, suddenly returns to the original state, which causes a problem that a swing-back shock (so-called release shock) of the automatic transmission occurs. In addition, as shown by a broken line, the accumulator 109 ′
Is provided facing the first branch hydraulic pressure supply passage 104, the release shock occurs because the release of the hydraulic pressure in the reverse clutch 106 precedes the release of the hydraulic pressure in the low reverse brake 107, though slightly delayed. .

Therefore, as shown in FIG. 12, the shift valve 11 is connected to the second branch hydraulic pressure supply passage 105 on the low reverse brake side from the connection with the accumulator 109.
1 (for example, a 1-2 shift valve), and when the shift is made from the reverse range to the non-reverse range, the shift valve 111 is shifted in synchronization with this to shut off the second branch hydraulic pressure supply passage 105, Reverse brake 1
The hydraulic pressure in 07, via the low-reverse brake-side portion 105a of the second branch hydraulic pressure supply passage 105, the hydraulic mechanism F ₂ has been proposed which is adapted to release from the drain port 112 of shift valve 111.

In the conventional hydraulic mechanism F ₂ as shown in FIG. 12, only the hydraulic oil discharged from the reverse clutch 106 flows from the accumulator 109 to the manual valve side portion 105 b of the second branch hydraulic supply passage 105. The release of the hydraulic pressure in the reverse clutch 106 is made relatively slow because it interferes with the hydraulic oil discharged through the clutch. For example, the low reverse brake 1 at a predetermined pressure P ₁
07 is turned off, the reverse clutch 1 at a predetermined pressure P ₂
06 in the hydraulic mechanism F ₂ that is set to be off, showing changes characteristic for the hydraulic time in the low reverse brake 107 and the reverse clutch 106 when the hydraulic release 10. In this example, the shift from the reverse range to the non-reverse range at time theta _1, the low reverse brake 107 is turned off by the theta _2, the reverse clutch 1
06 is turned off later at θ ₃ , so that no release shock occurs.

[0010]

However, FIG.
In conventional hydraulic mechanism F ₂ as shown in, such as by variations in component dimensions as shown in FIG. 10, if the hydraulic pressure release characteristics of the reverse clutch 106 is shifted as indicated by a chain line in FIG 10, a reverse clutch 106 Is turned off at time θ ₃ ′ before θ _2, and in this case, there is a problem that the release shock described above occurs.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems. In an automatic transmission for an automobile, it is possible to prevent the occurrence of an engagement shock and to change a reverse range to a non-reverse range. During the shift to
An object of the present invention is to provide a control device for an automatic transmission that can reliably delay the reverse clutch off operation from the low reverse brake off operation and prevent the occurrence of a release shock due to the return of the engine mount. And

[0012]

In order to achieve the above object, a first aspect of the present invention is to provide (i) a reverse range hydraulic supply passage to which hydraulic pressure is supplied when the manual valve takes a reverse range position; ii) First branch branched from the reverse range hydraulic supply passage and connected to the reverse clutch
A branch hydraulic supply passage, and (iii) a second branch branched from the reverse range hydraulic supply passage and connected to the reverse brake.
A branch hydraulic pressure supply passage, (iv) an accumulator disposed facing the second branch hydraulic pressure supply passage, and (v) a manual valve interposed in the second branch hydraulic pressure supply passage on the reverse brake side from a connection portion with the accumulator. Is shifted in synchronism with the switching operation between the reverse range position and the non-reverse range position. In the reverse range, the manual valve side portion and the reverse brake side portion of the second branch hydraulic pressure supply passage are communicated. A shift valve for shutting off the communication of the second branch hydraulic pressure supply passage and releasing the hydraulic pressure on the reverse brake side portion of the second branch hydraulic pressure supply passage when shifting from the range to the non-reverse range. (Vi)
When the manual valve is shifted from the reverse range position to the non-reverse range position, the control device for the automatic transmission is provided with a back pressure increasing means for increasing the back pressure of the accumulator.

According to a second aspect of the present invention, in the control device for an automatic transmission according to the first aspect, the line pressure is introduced as a back pressure into the accumulator, and the pressure regulating valve for regulating the line pressure and the pressure regulating valve. A control device for an automatic transmission, characterized in that a line pressure control mechanism including an electromagnetic valve for controlling a control oil pressure of a pressure valve functions as a back pressure increasing means.

According to a third aspect of the present invention, there is provided a control apparatus for an automatic transmission according to the first or second aspect, wherein the reverse brake is a low reverse brake. .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
As shown in FIG. 2, an automatic transmission AT for an automobile has a torque converter 3 that changes the torque of the engine output shaft 1 (engine torque) and transmits the torque to the turbine shaft 2, and further transmits the torque of the turbine shaft 2. A speed change gear mechanism 5 is provided which shifts the rotation and reverses the output when the reverse gear is selected and outputs the output gear 4 to the drive wheel side. Here, the turbine shaft 2 is formed in a pipe shape, and a pump shaft 6 connected to the engine output shaft 1 is disposed in a hollow portion thereof. The pump shaft 6 allows the turbine shaft 2 to be located behind the transmission gear mechanism 5 (in FIG. 2). The oil pump 7 disposed on the left side) is driven to rotate.

The torque converter 3 is substantially composed of a pump 9 connected to the engine output shaft 1 via a connecting member 8.
A turbine 10 connected to the turbine shaft 2 and rotationally driven by hydraulic oil discharged from the pump 9, and a stator 11 for rectifying hydraulic oil returning from the turbine 10 to the pump 9 in a direction to promote rotation of the pump 9. The torque of the engine output shaft 1 is shifted at a speed ratio according to the difference in the number of revolutions between the pump 9 and the turbine 10. Here, the stator 11 is fixed to the transmission case 13 via a stator one-way clutch 12. A lock-up clutch 14 for directly connecting the engine output shaft 1 and the turbine shaft 2 is provided as needed.

The transmission gear mechanism 5 is a commonly known ordinary planetary gear system.
The small sun gear 15 having a relatively small diameter loosely fitted to the turbine shaft 2, the large sun gear 16 having a relatively large diameter loosely fitted to the turbine shaft 2 behind the small sun gear 15, and meshing with the small sun gear 15. A plurality of short pinion gears 17 (only one is shown), a long pinion gear 18 having a front portion (right side in FIG. 2) meshing with the short pinion gear 17 and a rear portion meshing with the large sun gear 16, and a ring gear 19 meshing with the long pinion gear 18; A carrier 20 that rotatably supports the short pinion gear 17 and the long pinion gear 18 is provided. In the transmission gear mechanism 5, the small sun gear 15, the large sun gear 1
6 or the carrier 20 serves as a torque input section, while the ring gear 19 serves as a torque output section at any speed. The ring gear 19 is connected to the output gear 4.

A plurality of clutches and brakes are provided to switch the torque transmission path in the transmission gear mechanism 5, that is, to switch the gear ratio or the rotation direction of the output gear 4. Specifically, a forward clutch 21 and a first one-way clutch 22 are interposed between the turbine shaft 2 and the small sun gear 15 in series.
A coast clutch 23 is interposed in parallel with the first and second 22. Then, the turbine shaft 2 and the carrier 20
, A 3-4 clutch 24 is interposed, and a reverse clutch 25 is interposed between the turbine shaft 2 and the large sun gear 16. The large sun gear 16
A 2-4 brake 26 composed of a band brake operated by a servo piston for fixing the large sun gear 16 at a predetermined shift speed is provided between the reverse clutch 25 and the reverse clutch 25. Further, between the carrier 20 and the transmission case 13 ', there is provided a low reverse brake 27 for fixing the carrier 20 at a predetermined gear, and a second one-way clutch 28 for receiving a reaction force of the carrier 20.
And are interposed in parallel. Hereinafter, these clutches and brakes will be collectively referred to as “friction engagement elements” as appropriate.

Then, each clutch 21, 23, 24, 25
By changing the on / off patterns of the brakes 26 and 27 and the various ranges or shift speeds shown in Table 1, various ranges or shift speeds can be obtained. Hereinafter, with reference to Table 1, a description will be given of a torque transmission path and a shift characteristic thereof in each range or shift speed.

[0020]

[Table 1]

(1) P range (parking range): All friction engagement elements are turned off. In this case, the torque of the turbine shaft 2 is not transmitted to the transmission gear mechanism 5. (2) R range (reverse range): reverse clutch 25
And the low reverse brake 27 are turned on, and the other frictional engagement elements are turned off. Since the low reverse brake 27 is turned on, the second one-way clutch 28 arranged in parallel with the low reverse brake 27 has no particular effect. The first one-way clutch 22 deviates from the torque transmission path and has no particular effect. In this case, the torque of the turbine shaft 2 is input to the large sun gear 16 via the reverse clutch 25. And low reverse brake 2
7, the large sun gear 16, the long pinion gear 18, and the ring gear 1 are fixed.
9 function as a fixed gear train that meshes in this order. Therefore, the torque input to the large sun gear 16 is transmitted through the gear train in the order described above, and is shifted at a large reduction ratio determined by the number of teeth of the large sun gear 16 and the number of teeth of the ring gear 19. Is output. In this R range, the ring gear 19 (output gear 4) rotates in the opposite direction to the large sun gear 16 (turbine shaft 2), and the drive wheels are driven to the reverse side. (3) N range (neutral range) ... similar to the case of the P range. (4) D range (drive range) first speed: The forward clutch 21 is turned on, and the other frictional engagement elements are turned off. The first and second one-way clutches 22 and 28 are normally in a locked state, but idle during coasting. In this case, the torque of the turbine shaft 2 is sequentially input to the small sun gear 15 via the forward clutch 21 and the first one-way clutch 22. And the second
Since the carrier 20 is fixed by the one-way clutch 28, the small sun gear 15, the short pinion gear 17, the long pinion gear 18, and the ring gear 19 function as a fixed gear train that meshes in this order.
Therefore, the torque input to the small sun gear 15 is transmitted through the gear train in the above order, and is shifted at a large reduction ratio determined by the number of teeth of the small sun gear 15 and the number of teeth of the ring gear 19, and is transmitted to the output gear 4. Is output. In this case, the ring gear 19 (output gear 4) rotates in the same direction as the small sun gear 15 (turbine shaft 2), and the drive wheels are driven forward. In the first range of the D range, engine braking cannot be obtained by the action of the first one-way clutch 22. (5) D range 2nd speed: The forward clutch 21 and the 2-4 brake 26 are turned on, and the other friction engagement elements are turned off. The first one-way clutch 22 is normally in a locked state, but idles during coasting. Note that the second one-way clutch 28 always idles. In this case, since the large sun gear 16 is fixed, the long pinion gear 18 rotates while the large sun gear 16 rotates.
Revolves around. Therefore, although torque is transmitted basically in the same route as in the case of the first speed of the D range, the rotation speed of the ring gear 19 becomes higher by the revolution of the long pinion gear 18, so that the speed is slightly reduced compared to the first speed of the D range. The ratio becomes smaller. In the second range of the D range, engine braking cannot be obtained by the action of the first one-way clutch 22.

(6) D range 3rd speed: forward clutch 2
1, the coast clutch 23 and the 3-4 clutch 24 are turned on, and the other frictional engagement elements are turned off. Since the coast clutch 23 is turned on, the forward clutch 21 and the first one-way clutch 22 arranged in parallel therewith have no particular effect. Note that the second one-way clutch 28 always idles. In this case, the small sun gear 15 and the carrier 20
Locked together by the coast clutch 23, the turbine shaft 2 and the 3-4 clutch 24, so that all gears 15-19 and the carrier 20 are fixed and rotate together according to the general nature of the planetary gear system. Thus, the turbine shaft 2 and the output gear 4 are directly connected to each other, so that the torque of the turbine shaft 2 is transmitted to the output gear 4 without shifting (reduction ratio 1). In this case, the output gear 4 rotates in the same direction as the turbine shaft 2, and the drive wheels are driven forward. It is natural that engine braking can be obtained in the third range of the D range in the directly connected state.

(7) D range 4th speed: forward clutch 2
The 1 and 3-4 clutches 24 and the 2-4 brake 26 are turned on, and the other frictional engagement elements are turned off. The first and second one-way clutches 22 and 28 always idle. The first
Since the one-way clutch 22 is always idle, the forward clutch 21 is on, but does not exert any particular effect. In this case, the torque of the turbine shaft 2 is input to the carrier 20 via the 3-4 clutch 24, and the torque of the carrier 20 is sequentially transmitted to the output gear 4 via the long pinion gear 18 and the ring gear 19. . 2-
Since the large sun gear 16 is fixed by the four brakes 26, the long pinion gear 18 revolves around the large sun gear 16 while rotating. Therefore, the rotation speed of the ring gear 19 is higher than the rotation speed of the carrier 20, that is, the rotation speed of the turbine shaft 2 by the rotation of the long pinion gear 18, and the transmission gear mechanism 5 is in an overdrive (increased) state. The ring gear 19 (output gear 4) rotates in the same direction as the carrier 20 (turbine shaft 2), and the drive wheels are driven forward.

(8) 2nd range 1st speed: The same as the case of the D range 1st speed. (9) 2nd range 2nd speed: The forward clutch 21, the coast clutch 23, and the 2-4 brake 26 are turned on, and the other friction engagement elements are turned off. Since the coast clutch 23 is turned on, the forward clutch 21 and the first one-way clutch 22 arranged in parallel therewith have no particular effect. In this case, the torque transmission path and the shift characteristics are basically the same as those in the case of the second speed in the D range, but since the first one-way clutch 22 does not operate, engine braking can be obtained. (10) 2nd range 3rd speed: The same as in the case of the D range 3rd speed. (11) 1st range 1st speed: The forward clutch 21, coast clutch 23 and low reverse brake 27 are turned on, and the other frictional engagement elements are turned off. Since the coast clutch 23 is turned on, the forward clutch 21 and the first one-way clutch 22
Does not exert any special action, and since the low reverse brake 27 is turned on, the second one-way clutch 28 disposed in parallel with this does not exert any special action. In this case, the torque transmission path and the shift characteristics are basically the same as those in the case of the first speed in the D range, but since the first and second one-way clutches 22 and 28 do not operate, engine braking can be obtained. . (12) 1st range 2nd speed: Same as 2nd range 2nd speed.

Hereinafter, a hydraulic mechanism for turning on / off each friction engagement element of the transmission gear mechanism 5 will be described. 3 to 7
As shown in FIG. 3, the hydraulic mechanism FS is substantially
A line pressure control mechanism L for controlling the line pressure (source pressure) of S;
A hydraulic passage network M composed of a number of hydraulic passages for supplying or releasing hydraulic pressure to predetermined members, respectively, and a manual for switching a line pressure supply path shifted in response to a select operation of a select lever (not shown). Valve 31
And three shift valves 33 to 35 that are shifted by the control unit 32 in accordance with the shift position of the manual valve 31 and the driving state of the vehicle (for example, the vehicle speed and the throttle opening). Four accumulators 36 to 39 for buffering the supply or release of hydraulic pressure, three timing valves 41 to 43 and a bypass valve 44 for adjusting the supply or release timing of hydraulic pressure to a predetermined frictional engagement element, a torque converter 3 and a lock-up control mechanism U for controlling the supply of hydraulic pressure to the lock-up clutch 14, and a number of orifices and one-way valves for adjusting the flow resistance of a predetermined portion of the hydraulic passage network M. The orifices and one-way valves are indicated by commonly used marks, but are not individually numbered.

Then, the selected range (P, R, N,
(D, 2, 1 range) and the operating state of the vehicle, the hydraulic pressure applied to each frictional engagement element is controlled by the hydraulic mechanism FS, and the gear stage of the transmission gear mechanism 5 is switched. . Here, the 2-4 brake 26 is a servo piston type band brake having an apply port 26a and a release port 26b, and is turned on (brake operation) when hydraulic pressure is applied only to the apply port 26a. When both ports 26a and 26b are under hydraulic pressure or when both are released, the brakes are released (brake release). All other frictional engagement elements are turned on when hydraulic pressure is applied and turned off when hydraulic pressure is released.

The line pressure control mechanism L basically uses a pressure regulator valve 50 to supply a hydraulic pressure (line pressure) substantially proportional to the pilot pressure to the line pressure supply passage 5.
1. The line pressure in the line pressure supply passage 51 is supplied to the manual valve 31 and the like. The hydraulic oil in the line pressure supply passage 51 is supplied to the pressure regulator valve 5.
From 0, it is also supplied to the torque converter 3 via a torque converter oil passage 53 provided with a relief valve 52.

The pilot pressure supplied to the pressure regulator valve 50 is controlled by a pressure reducing valve 54, a modulator valve 55, a line pressure control accumulator 56, and a line pressure control solenoid valve 57 that is duty-controlled by the control unit 32. Is formed. Specifically, after the line pressure in the line pressure supply passage 51 is reduced by the pressure reducing valve 54, the line pressure is input to the input port 55 a of the modulator valve 55 via the pressure reducing oil passage 58. The oil pressure in the pressure reducing oil passage 58 is also introduced into the control port 55 b of the modulator valve 55 via the duty pressure passage 59.
Here, the hydraulic pressure applied to the control port 55b is controlled by a line pressure control solenoid valve 57 that opens and closes according to the duty ratio input from the control unit 32.
Is controlled by The duty ratio is set by the control unit 32 by a predetermined method according to the throttle opening, the vehicle speed, the selected range, the gear position, and the like, as described later.

Then, a hydraulic pressure corresponding to the hydraulic pressure applied to the control port 55b is output from the modulator valve 55 to the pilot pressure passage 61 as pilot pressure. Here, the hydraulic vibration or pulsation in the pilot pressure passage 61 is absorbed by the line pressure control accumulator 56. The pilot pressure thus formed is
The line pressure supplied to the pressure regulator valve 50 is proportional to the pilot pressure.
Formed. The pilot pressure in the pilot pressure passage 61 is also supplied to the cutback valve 62.

The manual valve 31 is provided with a select lever.
The shift is performed in conjunction with a selection operation (not shown), and the line pressure supply passage 51 communicates with a predetermined hydraulic supply passage in accordance with the selected range. Specifically, the line pressure supply passage 51 communicates with the first and second main hydraulic supply passages 63 and 64 in the D range and the second range, and the first and third main hydraulic supply passages 63 and 6 in the one range.
5, and in the R range, it communicates with the reverse range hydraulic supply passage 66, and in the P range and the N range, it does not communicate with any of the hydraulic supply passages 63 to 66.

Here, the first main hydraulic pressure supply passage 63 is
The hydraulic passage 63a branches to a hydraulic passage 63a for a -2 shift valve and a hydraulic passage 63b for a forward clutch. The hydraulic passage 63a for a 1-2 shift valve is connected to the first input port 33a of the 1-2 shift valve 33, The passage 63b is further branched and connected to the first input port 35a of the 3-4 shift valve 35 and the forward clutch 21. The second main hydraulic pressure supply passage 64 is connected to the first input port 34a of the 2-3 shift valve 34. The third main hydraulic pressure supply passage 65 is connected to a low reducing valve 67 (a pressure reducing valve) and a ball valve 68,
After being assembled in the second branch hydraulic passage 66b described later,
It is connected to the second input port 33b of the 1-2 shift valve 33. The reverse range hydraulic supply passage 66 is branched into a first branch hydraulic supply passage 66a and a 1-2 shift valve passage 66b. The first branch hydraulic supply passage 66a is connected to the reverse clutch 25 and is connected to the 1-2 shift valve. The valve passage 66b is connected to the second input port 33b of the 1-2 shift valve 33 via the ball valve 68.

Each of the shift valves 33 to 35 is basically controlled by the control unit 32, and changes the hydraulic pressure input from the input port from a predetermined output port in accordance with the selected range and gear position. The output is supplied to a predetermined friction engagement element or is released. Specifically, the 1-2 shift valve 33 is provided with the above-mentioned first and second input ports 33a and 33b and first and second output ports 33c and 33d, and the first output port 33c is The port 4a is connected to the apply port 26a of the 2-4 brake 26 via the port hydraulic passage 71, and the second output port 33d is connected to the low reverse brake 27 via the low reverse brake hydraulic passage 72.

The 2-3 shift valve 34 includes the first input port 34a, the second input port 34b,
Second output ports 34c and 34d are provided, the second input port 34b is connected to the first output port 35c of the 3-4 shift valve 35 via the first connection passage 73, and the first output port 34c is connected to the third output port 34c. It is connected to the 3-4 clutch 24 via the four-clutch hydraulic passage 74, and the second output port 34d
Is connected to the coast clutch 23 via a second connection passage 75, a ball valve 76, and a coast clutch hydraulic passage 77 described later. Further, a third connection passage 78 branched from the 3-4 clutch hydraulic passage 74 is provided, and the third connection passage 78 is connected to the second input port 35 b of the 3-4 shift valve 35.

The 3-4 shift valve 35 includes the first and second input ports 35a and 35b and the first output port 35 described above.
c and a second output port 35d, and the second output port 35d is connected to the second output port 35d through a release port hydraulic passage 81.
-4 The brake 26 is connected to the release port 26b of the brake 26, and is also connected to the coast clutch 23 via the coast clutch hydraulic passage 77. The release port hydraulic passage 81 and the coast clutch hydraulic passage 7
7 are gathered together near the second output port 35d.

The shift valves 33, 34, 35 are respectively
By switching the positions of the valve spools 33v, 34v, 35v to the ON position or the OFF position, the hydraulic transmission path in the shift valve can be switched. Here, the ON position is a position closer to the right in FIGS. 5 and 6, and the OFF position is a position closer to the left in FIGS. In addition,
5 and 6, each valve spool 33v, 34v,
The part above the center line of 35v shows the state where the on position is taken, and the part below the center line shows the state where the off position is taken. And, each valve spool 33v, 34v,
35v is provided with hydraulic pressure in the control oil chambers 33s, 34s, 35s provided at the right end of each shift valve 33, 34, 35.
Takes off position when (Pilot pressure) is applied,
When the pilot pressure is released, it is set to the ON position.

In the control oil chamber 33 s of the 1-2 shift valve 33, a first branch branched from the line pressure supply passage 51 is provided.
The control hydraulic passage 82 is connected, and the control unit 3 is connected to the first control hydraulic passage 82.
First solenoid valve 83 which is turned on / off by the second solenoid valve 83
Is interposed. Then, the first solenoid valve 83
Is turned on, the first control hydraulic passage 8
2, the pilot pressure in the control oil chamber 33s is released,
The valve spool 33v assumes the ON position. At this time, the first output port 33c communicates with the first input port 33a, and the second output port 33d communicates with the drain port (marked with x) and is opened. On the other hand, when the first solenoid valve 83 is turned off, the control oil chamber 33
Pilot pressure is applied to s, and the valve spool 33v assumes the off position. At this time, the first output port 33c is opened, and the second output port 33d communicates with the second input port 33b.

A second control hydraulic passage 84 branched from the forward clutch hydraulic passage 63b is connected to the control oil chamber 34s of the 2-3 shift valve 34.
A second solenoid valve 85 which is turned on / off by the control unit 32 is interposed in the second control hydraulic passage 84. Also in this case, similarly to the case of the 1-2 shift valve 33, the second solenoid valve 8
In response to the ON / OFF operation of No. 5, the valve spool 34v takes the ON position or the OFF position. Here, when the valve spool 34v is in the ON position, the first output port 3
4c is open, and the second output port 34d communicates with the second input port 34b. On the other hand, when the valve spool 34v assumes the off position, the first output port 34c communicates with the first input port 34a, and the second output port 34d is opened.

The control oil chamber 35s of the 3-4 shift valve 35 is connected to a third control hydraulic passage 86 branched from a second control hydraulic passage 84. The third control hydraulic passage 86 is connected to a control unit. A third solenoid valve 87 that is turned on and off by the switch 32 is provided. In this case as well, like the case of the 1-2 shift valve 33, the third solenoid valve 87
, The valve spool 35v takes the on position or the off position. Here, the valve spool 3
When 5v is in the ON position, the first and second output ports 35c and 35d are both opened. On the other hand, when the valve spool 35v is in the off position, the first output port 35c communicates with the first input port 35a, and the second output port 35d communicates with the second input port 35b.

As described above, when hydraulic pressure is suddenly supplied or released to each of the friction engagement elements, an engagement shock (shift shock) occurs. 1-2
An accumulator 36 is provided, an NR accumulator 37 is provided for the 1-2 shift valve passage 66b, and an N-R accumulator 37 is provided for the forward clutch hydraulic passage 63b.
A D accumulator 38 is provided, and a 2-3 accumulator 39 is provided for the 3-4 clutch hydraulic passage 74. Here, each of the accumulators 36 to 39 has:
Back pressure passages 89 branched from the line pressure supply passage 51, respectively.
, The line pressure is supplied as a back pressure.

3-2 timing for adjusting the on / off timing of a predetermined frictional engagement element so as not to cause an internal lock (double lock) state or the like in the transmission gear mechanism 5 at the time of switching between the range and the gear position. A valve 41, a 2-3 timing valve 42, a coast timing valve 43, and a bypass valve 44 are provided.

The lock-up control mechanism U includes a lock-up shift valve 91 and a lock-up control valve 9.
2 and a lock-up mechanism provided with first and second lock-up control solenoid valves 93 and 94. The lock-up mechanism supplies hydraulic oil to the torque converter 3 through a hydraulic oil supply passage 95 and a torque converter. The hydraulic oil in the pump 3 is guided to an oil cooler 97 via a hydraulic oil return passage 96, and hydraulic pressure is supplied to the lock-up clutch 14 via a hydraulic passage 98 for a lock-up clutch as required. .

By the hydraulic mechanism FS, the hydraulic pressure to each frictional engagement element is turned on / off according to the range position of the manual valve 31 and the on / off state of the first to third solenoid valves 83, 85, 87. Are controlled so that various ranges or shift speeds as shown in Table 1 can be obtained. Table 2 shows ON / OFF patterns of the first to third solenoid valves 83, 85, 87 corresponding to each range (P, R, N, D, 2, 1 range) or the shift speed. In addition,
In the P range or the N range, the hydraulic pressure is not supplied from the manual valve 31 to any of the first to third main hydraulic pressure supply passages 63 to 65 and the reverse range hydraulic pressure supply passage 66, so that the first to third solenoid valves 83 , 85,
No hydraulic pressure is supplied to any of the frictional engagement elements, regardless of the on / off state of 87. Therefore, all the frictional engagement elements are turned off, the transmission gear mechanism 5 enters a neutral state, and does not transmit torque.

[0043]

[Table 2]

Hereinafter, each driving range will be described with reference to Table 2.
The transmission path of the hydraulic pressure in the hydraulic mechanism FS in (R, D, 2, 1 range) or the shift speed will be described. (1) R range ...
The manual valve 31 takes the R range position, the first and second solenoid valves 83 and 85 are turned off, and the third solenoid valve 87 is turned on. In this case, hydraulic pressure is supplied to the reverse range hydraulic supply passage 66, and the hydraulic pressure is supplied to the reverse clutch 2 via the first branch hydraulic supply passage 66a.
5 and the reverse clutch 25 is turned on. The hydraulic pressure in the reverse range hydraulic pressure supply passage 66 is changed in the order of the 1-2 shift valve passage 66b, the second input port 33b of the 1-2 shift valve 33, the second output port 33d, and the low reverse brake. The low reverse brake 27 is supplied to the low reverse brake 27 via the hydraulic passage 72 for use. The other friction fastening elements are turned off because no hydraulic pressure is supplied. (2) D range 1st speed: The manual valve 31 is in the D range position (FIG. 5 shows this state), and hydraulic pressure is supplied to the first and second main hydraulic pressure supply passages 63 and 64. The same applies to the following D range 2 to 4 speeds. Then, the first solenoid valve 83 is turned off, and the second and third solenoid valves 85 and 87 are turned on. In this case, the hydraulic pressure in the first main hydraulic pressure supply passage 63 is supplied to the forward clutch 21 via the forward clutch hydraulic passage 63b, and the forward clutch 21 is turned on. Also,
Since no hydraulic pressure is output from any of the output ports of the shift valves 33 to 35, the other friction engagement elements are turned off.

(3) D range 2nd speed: The first to third solenoid valves 83, 85 and 87 are all turned on. In this case, the forward clutch 21 is turned on, as in the case of the D range first speed. Further, the hydraulic pressure in the first main hydraulic pressure supply passage 63 is sequentially changed to a 1-2 shift valve hydraulic passage 63a, a first input port 33a of the 1-2 shift valve 33, a first output port 33c, and an apply port. Is supplied to the apply port 26a of the 2-4 brake 26 via the hydraulic passage 71 for use. At this time, release port 2
Since no oil pressure is supplied to 6b, the 2-4 brake 26 is turned on. The other friction fastening elements are turned off because no hydraulic pressure is supplied.

(4) D range 3rd speed: The first solenoid valve 83 is turned on, and the second and third solenoid valves 85, 87
Is turned off. In this case, the forward clutch 21 is turned on and the hydraulic pressure is supplied to the apply port 26a, as in the case of the D range second speed. However, as explained later,
Since hydraulic pressure is also supplied to the release port 26b,
The 4 brake 26 is turned off. Then, the hydraulic pressure in the second main hydraulic pressure supply passage 64 is sequentially changed to the 2-3 shift valve 3.
4, a first input port 34a, a first output port 34c,
It is supplied to the 3-4 clutch 24 via the 3-4 clutch hydraulic passage 74, and the 3-4 clutch 24 is turned on.
The hydraulic pressure in the 3-4 clutch hydraulic passage 74 is, in order, the third connection passage 78, the second input port 35b of the 3-4 shift valve 35, the second output port 35d, and the coast clutch hydraulic passage. 77 and is supplied to the coast clutch 23, and the coast clutch 23 is turned on.
Further, the hydraulic pressure of the second output port 35d is supplied to the release port 26b of the 2-4 brake 26 via the release port hydraulic passage 81.
The fourth brake 26 is turned off. The reverse clutch 25 and the low reverse brake 27 are turned off because no hydraulic pressure is supplied.

(5) D range 4th speed: The first and third solenoid valves 83 and 87 are turned on, and the second solenoid valve 8
5 is turned off. In this case, the forward clutch 21 and the 2-4 brake 26 are turned on as in the case of the D range 2nd speed. Further, the 3-4 clutch is turned on, as in the case of the D range third speed. The other friction fastening elements are turned off because no hydraulic pressure is supplied. (6) 2nd range 1st speed: The manual valve 31 is in the 2nd range position, but the transmission path of the hydraulic pressure to the friction engagement element is the same as in the case of the D range 1st speed.

(7) 2nd range 2nd speed: The first and second solenoid valves 83 and 85 are turned on, and the third solenoid valve 8
7 is turned off. In this case, the forward clutch 21 and the 2-4 brake 26 are turned on as in the case of the D range 2nd speed. Further, the hydraulic pressure in the forward clutch hydraulic passage 63b is
In order, the first input port 35a of the 3-4 shift valve 35
, A first output port 35c, a first connection passage 73, and 2
A third input port 34b of the shift valve 34;
The coast clutch 2 is supplied to the coast clutch 23 through the output port 34d, the second connection passage 75, the ball valve 76, and the coast clutch hydraulic passage 77.
3 is turned on. The other friction fastening elements are turned off because no hydraulic pressure is supplied. (8) 2nd range 3rd speed: The same as in the case of the D range 3rd speed.

(9) 1-speed 1-range: manual valve 31
Takes one range position, and hydraulic pressure is supplied to the first and third main hydraulic pressure supply passages 63 and 65. The first and third solenoid valves 83 and 87 are turned off, and the second solenoid valve 85
Is turned on. In this case, the forward clutch 21 is turned on as in the case of the D range first speed, and the coast clutch 23 is turned on as in the case of the two range second speed. Further, the hydraulic pressure in the third main hydraulic pressure supply passage 65 is sequentially reduced by the low reducing valve 67, the ball valve 68, the 1-2 shift valve passage 66 b, and the 1-2 shift valve 33.
The low reverse brake 27 is turned on by being supplied to the low reverse brake 27 via the input port 33b, the second output port 33d, and the low reverse brake hydraulic passage 72. The other friction fastening elements are turned off because no hydraulic pressure is supplied. (10) 1st range 2nd speed ... The manual valve 31 is in the 1st range position, but the hydraulic pressure transmission path to the friction engagement element is the same as in the 2nd range 2nd speed.

As described above, the on / off pattern of the frictional engagement element as shown in Table 1 is obtained corresponding to the on / off pattern of the solenoid valve as shown in Table 2, and the predetermined range or shift speed is changed. can get.

By the way, the hydraulic mechanism FS is particularly
Although it is configured to effectively prevent the occurrence of the engagement shock when the range is selected, and to effectively prevent the generation of the release shock when shifting from the R range to the N range or the P range. This will be described below. As shown in FIG. 1, the hydraulic pressure is directly supplied from the reverse range hydraulic supply passage 66 to the reverse clutch 25 via the first branch hydraulic supply passage 66a. On the other hand, a series of hydraulic supply passages 66b and 72 (hereinafter, collectively referred to as a second branch hydraulic supply passage K) extending from the reverse range hydraulic supply passage 66 to the low reverse brake 27 are provided from the manual valve 31 side. In order, a one-way orifice 99, an NR accumulator 37, and a 1-2 shift valve 33 are provided. The hydraulic passage 66 to the NR accumulator 37
A one-way orifice 100 is also provided in c.
The low reverse brake 27 is provided with a dish plate (not shown) for buffering a change in hydraulic pressure.

In this configuration, when the R range is selected, the reverse range input port 31a and the reverse range output port 3
1b (FIG. 1 shows this state). Then, as described above, the valve spool 33v of the 1-2 shift valve 33 takes the off position (FIG. 1 shows this state), and the second input port 33b and the second output port 33d.
Communicates with At this time, the hydraulic pressure in the line pressure supply passage 51 is supplied to the reverse range hydraulic supply passage 66, and the hydraulic pressure is supplied to the reverse clutch 25 via the first branch hydraulic supply passage 66a with almost no response delay.
The reverse clutch 25 is turned on. The hydraulic pressure in the reverse range hydraulic pressure supply passage 66 is also supplied to the low reverse brake 27 via the second branch hydraulic pressure supply passage K, but the NR accumulator 37 is supplied to the second branch hydraulic pressure supply passage K. Is provided, the rise of the hydraulic pressure supplied to the low reverse brake 27 is buffered by the pressure accumulating action of the NR accumulator 37, and the change in the hydraulic pressure is also buffered by the dish plate. Is turned on with a moderate response delay. Here, the transmission gear mechanism 5 (see FIG. 2)
Since the reverse drive state is established when both the reverse clutch 25 and the low reverse brake 27 are turned on, the timing of the reverse drive is determined by the low reverse brake 27. Therefore, the shift speed is switched at a moderately moderate timing, and the occurrence of the engagement shock is effectively prevented.

On the other hand, from the R range to the non-reverse range (N,
When shifting to (P range), basically, the release port 31c of the manual valve 31 and the drain port 31d communicate with each other, and in synchronization with this, the valve spool 33v of the 1-2 shift valve 33 is set to the ON position. The shift is performed, and the second output port 33d communicates with the drain port 33e. Therefore, the hydraulic pressure in the reverse clutch 25 is released from the drain port 31d of the manual valve 31, and the hydraulic pressure in the low reverse brake 27 is released from the drain port 33e of the 1-2 shift valve 33. The drain port 33 of the 1-2 shift valve 33
d is provided with an orifice 33f for adjusting the flow resistance, that is, the drain speed. However, as described above, if the reverse clutch 25 is turned off earlier than the low reverse brake 27, a release shock will occur. Therefore, when shifting from the R range to the N range, the control unit 32 uses the switching line. By performing the pressure control, the back pressure of the NR accumulator 37 is increased, so that the reverse clutch 25 is reliably turned off after the low reverse brake 27.

The control method of the line pressure control by the control unit 32 will be described below with reference to the flowchart shown in FIG. In the line pressure control, basically, in the non-reverse range, normal line pressure control is performed in step # 11 according to the throttle opening, the vehicle speed, and the like.
At the time of the range, the line pressure control for the normal R range is performed in step # 15, and when the shift from the R range to the non-reverse range is performed, the line pressure control for switching is performed for a predetermined time in step # 9.

More specifically, first, in step # 1, the range position of the manual valve 31, that is, the selected range is read, and subsequently, in step # 2, it is determined whether the R range is selected or not. Is done. Here, if it is determined that the range is the R range (YES), it is compared and determined in step # 12 whether or not the previous range was also the R range. If it is determined that the range was also the last time (YE
S) Since the operation in the R range is continued, ordinary line control for the R range is performed in step # 15, and thereafter, the process returns to step # 1.

On the other hand, if it is determined in the step # 12 that the previous time is not the R range (NO), it means that the shift to the R range has been made from this time. The one solenoid valve 83 is turned off, and the switching flag F is reset to 0 in step # 14. As described above, in the R range, it is necessary to shift the valve spool 33v of the 1-2 shift valve 33 to the off position. When the shift flag F is shifted from the R range to the non-reverse range, step # 7 is performed.
Is set to 1 and the flag is returned to 0 in step # 10 when the line pressure control for switching is completed. However, when the line pressure is shifted to the R range while the line pressure control for switching is continued, step # 10 is executed. Is not returned to 0, so step #
At 14 it is reset to zero. Subsequently, normal line pressure control for the R range is started in step # 15, and thereafter, the process returns to step # 1.

If it is determined in step # 2 that the switch is not in the R range (NO), it is determined in step # 3 whether the switch flag F is 1 or not, and it is determined that the switch flag F is not 1. If (NO), further, in step # 4, it is determined whether or not the previous range was the R range. Here, if the previous range is not the R range (NO), the operation in the non-reverse range is continued, so that normal line pressure control is performed in step # 11, and thereafter, the process returns to step # 1. I do.

If it is determined in step # 4 that the previous time was in the R range (YES), the shift from the R range to the non-reverse range has now been performed.
At 5, the timer for counting the time during which the line pressure control for switching is to be performed starts counting, the first solenoid valve 83 is turned on at step # 6, and the switching flag F is set to 1 at step # 7. Since the manual valve 31 is shifted to the non-reverse range position and the first solenoid valve 83 is turned on, as described above, the hydraulic pressure in the reverse clutch 25 increases the first branch hydraulic pressure supply passage 66a.
And the hydraulic pressure in the low reverse brake 27 is released from the drain port 31d of the manual valve 31 through the reverse range hydraulic supply passage 66, and the hydraulic pressure in the low reverse brake 27 is reduced to 1-2 shift 3 through the low reverse brake hydraulic passage 72.
3 is released from the drain port 33e. As will be described later, the switching line pressure control is performed for a predetermined time, so that the reverse clutch 25 is reliably turned off with a delay from the low reverse brake 27.

Next, it is determined in step # 8 whether or not the timer has counted up. If the timer has not counted up (NO), the line pressure control at the time of switching is performed in step # 9. If yes (YES), the switching flag F is returned to 0 in step # 10, and
At 11, normal line pressure control is started. Thereafter, the process returns to step # 1.

When the line pressure control for switching is performed, the duty ratio applied to the line pressure control solenoid valve 57 is reduced by a predetermined value, and the line pressure is correspondingly increased. Since the line pressure is supplied as back pressure to the back pressure oil chamber 37b of the NR accumulator 37 through the back pressure passage 89, the line pressure is increased in this manner, and as a result, a high back pressure (line Pressure) by N
The hydraulic oil in the accumulator oil chamber 37a of the -R accumulator 37 is discharged to the hydraulic passage 66c with a relatively high pressure.
The hydraulic oil with a relatively high pressure flows into the reverse range hydraulic supply passage 66 via the 1-2 shift valve passage 66b. At this time, the hydraulic pressure or hydraulic oil in the reverse clutch 25 is also supplied to the first branch hydraulic supply passage 6.
An attempt is made to flow into the reverse range hydraulic pressure supply passage 66 from the branch portion 66d through 6a. However, NR
Since the pressure of the hydraulic oil flowing into the branch portion 66d from the accumulator 37 side is high, the hydraulic oil on the reverse clutch 25 side is prevented from flowing into the reverse range hydraulic supply passage 66.

Accordingly, the release of hydraulic pressure or hydraulic oil from the reverse clutch 25 to the drain port 31d is as follows:
Substantially, the accumulator oil chamber 37a of the NR accumulator 37
It will be delayed by the time required for the hydraulic oil inside to be discharged. Therefore, as shown in FIG. 9, when shifted from the R range to the N range at time t _1, the release characteristics of the hydraulic or hydraulic oil from the reverse clutch 25 is as shown in curve H _2, the reverse clutch 25 It is turned off at t _3. In this case, as is apparent from FIG.
Even if there is a slight variation in ₂ , the reverse clutch 25
The time at which is turned off hardly changes. On the other hand, the hydraulic pressure or hydraulic oil in the low reverse brake 27 depends on the spring characteristics of the dish plate provided in the low reverse brake 27 and the drain port 33 regardless of the line pressure.
According to the resistance characteristics of the orifice 33f provided in e,
For example released in characteristic as shown by curve H _1, the low reverse brake 27 is turned off at t _2.

Therefore, since the reverse clutch 25 is surely turned off after the low reverse brake 27, it is possible to effectively prevent the occurrence of the release shock due to the release of the reverse driving force. As described above, according to the present invention, the occurrence of the engagement shock when the R range is selected is prevented, and the generation of the release shock when the shift from the R range to the non-reverse range is prevented.

[0063]

According to the first aspect of the invention, when the reverse range is selected, the supply of the hydraulic pressure to the friction engagement element is buffered by the accumulator, so that the engagement shock is reduced. Also, when shifting from the reverse range to the non-reverse range, the back pressure of the accumulator is increased, so that the pressure of the hydraulic oil discharged from the accumulator causes a time delay in the release of hydraulic pressure or hydraulic oil from the reverse clutch, , The reverse clutch is released later than the reverse brake. Therefore, the occurrence of the release shock is prevented.

According to the second aspect, basically, the same operation and effect as those of the first aspect can be obtained. In addition, the back pressure of the accumulator is increased by increasing the line pressure by the line pressure control mechanism including the pressure regulating valve and the solenoid valve.
There is no need to newly provide back pressure increasing means. Further, control of the back pressure is easy.

According to the third aspect, basically, the same operation and effect as those of the first or second aspect can be obtained. further,
Since the reverse brake is generally a low reverse brake provided with a dish plate, when shifting from the reverse range to the non-reverse range, the low reverse brake is released relatively slowly by the dish plate and thereafter the reverse clutch is released. ,
The release shock is more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a hydraulic mechanism around a reverse clutch and a low reverse brake.

FIG. 2 is a system configuration diagram of the automatic transmission.

FIG. 3 is a system configuration diagram of a hydraulic mechanism around a transmission.

FIG. 4 is a system configuration diagram of a hydraulic mechanism around a line pressure control mechanism.

FIG. 5 is a system configuration diagram around a manual valve and a 1-2 shift valve of the hydraulic mechanism.

FIG. 6 is a system configuration diagram of a hydraulic mechanism around a 2-3 shift valve and a 3-4 shift valve.

FIG. 7 is a system configuration diagram around a lock-up control mechanism of the hydraulic mechanism.

FIG. 8 is a flowchart illustrating a control method of line pressure control.

FIG. 9 is a diagram illustrating release characteristics of hydraulic pressures of a reverse clutch and a low reverse brake of the automatic transmission including the control device according to the present invention.

FIG. 10 is a diagram showing release characteristics of hydraulic pressure of a reverse clutch and a low reverse brake of a conventional automatic transmission.

FIG. 11 is a system configuration diagram around a reverse clutch and a low reverse brake of a hydraulic mechanism of a conventional automatic transmission.

FIG. 12 is a system configuration diagram around a reverse clutch and a low reverse brake of a conventional hydraulic mechanism in which a shift valve is interposed in a hydraulic pressure supply passage to a low reverse brake.

[Explanation of symbols]

 AT: Automatic transmission FS: Hydraulic mechanism K: Second branch hydraulic supply passage L: Line pressure control mechanism 5: Transmission gear mechanism 25: Reverse clutch 27: Low reverse brake 31: Manual valve 32: Control unit 33: 1-2 Shift valve 37 ... NR accumulator 50 ... Pressure regulator valve 57 ... Solenoid valve for line pressure control 66 ... Hydraulic supply passage for reverse range 66a ... First branch hydraulic supply passage 72 ... Hydraulic passage for low reverse brake

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16H 61/00-61/24

Claims (3)

(57) [Claims] 1. A hydraulic supply passage reverse range pressure is supplied when the manual valve took a reverse range position, the reverse branched from the hydraulic supply passage said reverse range
A first branch hydraulic pressure supply passage connected to the clutch, river branched from the hydraulic supply passage above the reverse range
A second branch hydraulic pressure supply passage connected to the brake , an accumulator arranged facing the second branch hydraulic pressure supply passage, and a second branch hydraulic pressure on the reverse brake side from a connection portion with the accumulator. interposed in the supply passage, it is shifted in synchronization with the switching operation between the reverse range position and a non-reverse range position of the manual valve, the reverse range and on the manual valve-side portion of the second branch oil supply passage
While communicating the serial reverse brake-side portion, when it is shifted from the reverse range to the non-reverse range, the reverse brake portion of the second branch oil supply passage while blocking the communication of the second branch oil supply passage An automatic transmission provided with a shift valve for releasing the hydraulic pressure, wherein when the manual valve is shifted from the reverse range position to the non-reverse range position, a back pressure increasing means for increasing the back pressure of the accumulator is provided. A control device for an automatic transmission. 2. A control device for an automatic transmission according to claim 1, wherein the line pressure is introduced into the accumulator as a back pressure, and a pressure regulating valve for regulating the line pressure and a control of the pressure regulating valve are provided. A control device for an automatic transmission, characterized in that a line pressure control mechanism having an electromagnetic valve for controlling oil pressure functions as back pressure increasing means. 3. The control device for an automatic transmission according to claim 1, wherein the reverse brake is a low reverse brake.