JP3299814B2 - 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 in series. The torque converter changes the torque of an engine output shaft and transmits the torque to a turbine shaft. The torque of the turbine shaft is further changed and transmitted to the drive wheels. Here, the transmission gear mechanism is generally a planetary gear mechanism having a plurality of gears such as a sun gear, a ring gear, and a pinion gear, and the transmission gear mechanism includes a clutch that turns on and off transmission of torque to a predetermined gear, Alternatively, various hydraulic friction elements such as a brake for fixing and releasing a predetermined gear are provided. And a hydraulic mechanism for supplying and discharging hydraulic pressure (hydraulic oil) to and from each of these friction elements is provided,
The on / off pattern of each friction element is switched by the hydraulic mechanism to perform gear shifting.

[0003] Conventionally, in the case of a four-speed forward and one-reverse single-speed transmission gear mechanism which has been frequently used, a servo piston type two- and four-speed servo piston type two- or four-speed fixed large sun gear is usually used.
Four brakes are provided. Such a 2-4 brake is provided with a servo apply chamber and a servo release chamber partitioned by a servo piston, and when hydraulic pressure is applied only to the servo apply chamber through the servo apply passage, the 2-4 brake is engaged, The 2-4 brake is released when the hydraulic pressure in the servo apply chamber is released or when the hydraulic pressure is applied to the servo release chamber through the servo release passage.

[0004] In general, when supplying or discharging hydraulic pressure to or from a friction element of an automatic transmission, if the rising or falling speed of the hydraulic pressure is too high, the friction element is rapidly engaged / released, causing a shift shock. In addition, there is a problem that it is difficult to take on / off timing between the friction elements. Therefore, an accumulator is provided for a predetermined hydraulic passage in the hydraulic mechanism to buffer the rise or fall of the hydraulic pressure and temporarily maintain the hydraulic pressure at a substantially constant value (creates a shelf pressure) (for example, 1962-14
No. 7153). Incidentally, Japanese Patent Application Laid-Open No. 62-14715
In the automatic transmission disclosed in Japanese Patent Publication No. 3 (1993), the hydraulic characteristics of the accumulator can be changed by temporarily returning the shift valve to the original position during gear shifting. Specifically, for example, a 1-2 accumulator is provided for the servo apply passage to temporarily maintain the hydraulic pressure at a substantially constant value and to create a shelf pressure when supplying and discharging the hydraulic pressure to and from the servo apply chamber. Can be

[0005]

In such an automatic transmission in which the 1-2 accumulator is provided for the servo apply passage, the hydraulic pressure is released from the speed at which the hydraulic pressure is applied to the servo apply chamber. When shifting to another shift speed, for example, when shifting from the second speed to the first speed, the hydraulic pressure in the servo apply chamber increases by a predetermined valve, for example, 1
-Drained via shift valve. At this time, the hydraulic pressure in the servo apply passage decreases, and accordingly, 1-
The hydraulic pressure in the accumulator 2 is released to the servo apply passage. However, in the initial stage, the hydraulic pressure in the 1-2 accumulator is rapidly released to the servo apply passage, and this hydraulic pressure is transmitted to the servo apply chamber. ,
Once the hydraulic pressure in the servo apply chamber has dropped temporarily
(For a moment) it rises. For this reason, once released 2
-4 The brake is temporarily (for a moment) re-engaged temporarily, which causes a shock or hesitation, which causes a problem that the driving feeling is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. When a gear is released by removing the hydraulic pressure from a gear at which a hydraulic pressure is applied to the servo apply chamber, a shock or hesitation may occur. It is an object of the present invention to provide a control device for an automatic transmission, which can prevent the occurrence and enhance the running feeling.

To achieve the above object, the present invention provides
(I) a speed change gear mechanism having a plurality of shift speeds including first to fourth forward speeds, a plurality of hydraulic friction elements for changing the speed by switching power transmission characteristics in the speed change gear mechanism, and the friction elements And (ii) the friction element is engaged when hydraulic pressure is applied to the servo apply chamber through the servo apply passage, and is released when the hydraulic pressure is released or when the servo release is performed. This includes a servo piston type brake that is released when hydraulic pressure is applied to the servo release chamber through the passage, and a 3-4 clutch that is engaged at the third and fourth speeds. (Iii) The hydraulic pressure to the servo apply chamber is included. A 1-2 shift valve for controlling supply / discharge, a pressure regulating valve for adjusting the hydraulic pressure of the 3-4 clutch, and a solenoid valve for controlling supply of pilot pressure to the pressure regulating valve are provided. (Iv) a control device for an automatic transmission in which an accumulator is provided in the servo apply passage; (v) a shift from the fourth speed to the first speed and a shift from the third speed to the first speed; In shifting from the second speed to the first speed, a shift control means is provided for releasing the hydraulic pressure in the servo apply chamber through a state in which the hydraulic pressure is applied to the servo release chamber and the hydraulic pressure of the 3-4 clutch is released. (Vi) when the hydraulic control means releases the hydraulic pressure of the servo apply chamber during the shift from the fourth speed to the first speed, the shift from the third speed to the first speed, and the shift from the second speed to the first speed, Open the solenoid valve and set the pilot pressure to 1-
By draining through a 2-shift valve, 3-
A control device for an automatic transmission, characterized in that the hydraulic pressure of a four clutch is drained via the pressure regulating valve.

[0008]

[0009]

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
As shown in FIG. 2, the automatic transmission AT includes a torque converter 3 that changes the torque of the engine output shaft 1 and outputs the torque to the turbine shaft 2, and an output gear 4 (drive) that further changes the torque of the turbine shaft 2. (A wheel side). 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 of the turbine shaft 2. An oil pump 7 is rotated by the pump shaft 6. I have.

The torque converter 3 is substantially connected to the engine output shaft 1 via a pump cover 8 and rotates integrally with the engine output shaft 1, and the pump 9 rotates integrally with the turbine shaft 2. 10 that is rotationally driven by hydraulic oil discharged from
And a stator 11 that rectifies the hydraulic oil returning from the pump 9 to the direction in which the rotation of the pump 9 is assisted, and at a gear ratio according to a rotational speed difference between the pump 9 and the turbine 10,
The torque of the engine output shaft 1 is changed. Here, the stator 11 is connected to a transmission case 13 (fixed portion) via a stator one-way clutch 12. In order to reduce power loss and improve fuel efficiency, a lock-up clutch 14 is provided to directly connect the engine output shaft 1 and the turbine shaft 2 in a predetermined operation range.

The transmission gear mechanism 5 is an ordinary planetary gear mechanism. The transmission gear mechanism 5 has a relatively small diameter small sun gear 15 loosely fitted to the turbine shaft 2 and a rear side of the small sun gear 15 (see FIG. 1). 2, a large sun gear 16 of relatively large diameter loosely fitted to the turbine shaft 2 at the turbine shaft 2, a plurality of short pinion gears 17 (only one is shown) meshing with the small sun gear 15, and a front portion (right side in FIG. 2). Long pinion gear 18 meshing with short pinion gear 17 and rear portion meshing with large sun gear 16
And a ring gear 19 that meshes with the long pinion gear 18 and a carrier 2 that rotatably (rotates) the short pinion gear 17 and the long pinion gear 18.
0 is provided. In the transmission gear mechanism 5, the small sun gear 15, the large sun gear 16 or the carrier 20 serves as a torque input unit according to the selected shift speed, while the ring gear 19 serves as a torque output unit at any shift speed. The ring gear 19 is connected to the output gear 4.

A plurality of hydraulic friction elements such as clutches and brakes are provided for switching a power transmission path (torque transmission path) in the transmission gear mechanism 5, that is, for switching a gear ratio or a rotating direction. ing. Specifically, the turbine shaft 2 and the small sun gear 15
, A forward clutch 21 and a first one-way clutch 22 are interposed in series, and a coast clutch 23 is interposed in parallel with both clutches 21, 22. A 3-4 clutch 24 is provided between the turbine shaft 2 and the carrier 20, and a reverse clutch 25 is provided between the turbine shaft 2 and the large sun gear 16. Further, between the large sun gear 16 and the reverse clutch 25, there is provided a band brake which is operated by a servo piston for fixing the large sun gear 16 at a predetermined shift speed.
Four brakes 26 are provided. The 2-4 brake 26 is provided with a servo apply chamber 26a and a servo release chamber 26b partitioned by a servo piston (not shown) (see FIG. 1). 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.

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. In addition, on / off of each friction element is switched by a hydraulic mechanism F controlled by the control unit 30 as described later (see FIG. 1).

[0015]

[Table 1]

(1) P range: All friction elements are turned off. In this case, the torque of the turbine shaft 2 is not transmitted to the output gear 4. (2) R range: the reverse clutch 25 and the low reverse brake 27 are turned on, and the other friction elements are turned off.
The first and second one-way clutches 22, 28 have no particular effect. The torque of the turbine shaft 2 is input to the large sun gear 16 via the reverse clutch 25, and the large sun gear 16, the long pinion gear 18, and the ring gear 19 function as a fixed gear train that meshes in this order. In this case, the torque input to the large sun gear 16 is shifted at a reduction ratio determined by the number of teeth of the large sun gear 16 and the number of teeth of the ring gear 19, and is output from the output gear 4. In this R range, the ring gear 19 (output gear 4) rotates in the direction opposite to the large sun gear 16 (turbine shaft 2), and the drive wheels are driven in the backward direction. (3) N range: Same as in the P range.

(4) 1st D range: forward clutch 2
1 is turned on and the other friction elements are turned off. 1st, 2nd
The one-way clutches 22 and 28 are normally locked but idle during coasting. The torque of the turbine shaft 2 is input to the small sun gear 15 via the forward clutch 21 and the first one-way clutch 22, and the small sun gear 15 and the short pinion gear 1
7, the long pinion gear 18 and the ring gear 19 function as a fixed gear train that meshes in this order. In this case, the torque input to the small sun gear 15 is shifted from the output gear 4 at a reduction ratio determined by the number of teeth of the small sun gear 15 and the number of teeth of the ring gear 19. 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 in the forward direction. In the first range of the D range, engine braking cannot be obtained due to the operation of the first one-way clutch 22.

(5) D range 2nd speed: forward clutch 2
The 1 and 2-4 brakes 26 are turned on, and the other friction elements are turned off. The first one-way clutch 22 is normally locked, but idles during coasting, and the second one-way clutch 28 always idles. Large sun gear 1
6 is fixed, the long pinion gear 18 revolves around the large sun gear 16 while rotating. Therefore, basically, torque is transmitted along the same route as in the case of the D range first speed, but the rotation of the ring gear 19 increases by the revolution of the long pinion gear 18 and the reduction ratio is smaller than that of the D range first speed. Become. In the second range of the D range, engine braking cannot be obtained due to 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 friction elements are turned off. The first one-way clutch 22 has no particular effect, and the second one-way clutch 28 always idles. Since the small sun gear 15 and the carrier 20 are locked to each other via the coast clutch 23, the turbine shaft 9 and the 3-4 clutch 24, the transmission gear mechanism 5 is directly connected. Therefore, the torque of the turbine shaft 2 is output from the output gear 4 without being shifted. It should be noted that the engine is in a directly connected state, so that the engine brake can be naturally obtained.

(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 friction elements are turned off. The first and second one-way clutches 22 and 28 always idle. 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
The power is transmitted to the output gear 4 via the long pinion gear 18 and the ring gear 19. Since the large sun gear 16 is fixed by the 2-4 brake 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 (turbine shaft rotation speed) by the rotation of the long pinion gear 18, and the transmission gear mechanism 5 is overdriven (increased speed).

(8) 2nd range 1st speed: The same as in 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 elements are turned off. The first one-way clutch 22 has no particular effect, and the second one-way clutch 28
Spins. 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 function, 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 friction elements are turned off. The first and second one-way clutches 22, 28 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 first speed in the D range, but since the first and second one-way clutches 22 and 23 do not function, engine braking can be obtained. (12) 1st range 2nd speed: Same as 2nd range 2nd speed.

Hereinafter, the hydraulic mechanism F for turning on and off each friction element of the transmission gear mechanism 5 will be described with reference to FIG. Since the general configuration of the hydraulic mechanism F for turning on and off the friction element of the transmission gear mechanism 5 is not the subject of the present invention, only the parts related to the subject of the present invention in the hydraulic mechanism F of FIG. Selectively illustrated,
Other parts are omitted.

As shown in FIG. 1, the hydraulic mechanism F has a manual valve 31 which is shifted in response to a select operation of a select lever (not shown) and switches a supply / discharge path of hydraulic pressure (hydraulic oil). The first to third shift valves 32 to 34 that are shifted by the control unit 30 according to the shift position of the vehicle and the driving state of the vehicle (for example, the vehicle speed and the throttle opening), and the servo release chamber 26b
Timing valve 35 (2-3 timing valve) for adjusting the supply / discharge timing of hydraulic pressure to the clutch, and second timing valve 36 (coast timing valve) for adjusting the supply / discharge timing of hydraulic pressure to the coast clutch 23
A first pressure adjusting valve 37 (3-4 control valve) for adjusting the oil pressure of the 3-4 clutch 24, a second pressure adjusting valve 38 (servo release control valve) for adjusting the oil pressure of the servo release chamber 26b, Servo apply room 26a
An accumulator 39 for buffering the supply and discharge of hydraulic pressure (hydraulic oil) to create a shelf pressure, a hydraulic passage network composed of a number of hydraulic passages, and a fluid passage network for adjusting a flow state of a predetermined portion of the hydraulic passage network. An orifice and a one-way valve are provided. Note that the control unit 30 is a comprehensive control device for the automatic transmission AT, including a “shift control unit” described in the claims, including a microcomputer.

Then, the selected range (P, R, N,
(D, 2, 1 range) and the operating state of the vehicle, the hydraulic pressure applied to each friction element is controlled by the hydraulic mechanism F, and the gear position of the transmission gear mechanism 5 is switched. The 2-4 brake 26 is turned on (brake operation) when hydraulic pressure is applied only to the servo apply chamber 26a. On the other hand, when the hydraulic pressure is applied to both the chambers 26a and 26b, when the hydraulic pressure is released to both the chambers 26a and 26b, or when the hydraulic pressure is applied only to the servo release chamber 26b, the brake is turned off (brake release). You. All other friction elements are turned on (fastened) when hydraulic pressure is applied, and turned off when the hydraulic pressure is released.
(To be released.

The manual valve 31 is provided with a select lever.
(Not shown), the valve spool 40 is shifted in the axial direction according to the selected range, and the line pressure supply passage 41 communicates with a predetermined hydraulic supply passage. I have. Note that the line pressure is preferably set according to the operation state. When the manual valve 31 is set to the D range (normal travel range), the manual valve 31 controls the line pressure in the line pressure supply passage 41 to the first main hydraulic passage 4.
2 through the first shift valve 32 (1-2 shift valve)
To the second shift valve 33 (2-3 shift valve) via the second main hydraulic passage 43. The third shift valve 34 (3-
The four shift valves are supplied with hydraulic pressure from the second shift valve 33.

Each of the first to third shift valves 32 to 34 is basically controlled by the control unit 30 and controls the hydraulic pressure input from the input port to a predetermined output in accordance with the selected range and gear position. Output from a port is supplied to a predetermined friction element or is released. Each of the shift valves 32, 33, 34 can switch the hydraulic pressure transmission path in the shift valve by switching the position of the valve spool 49, 56, 63 to an on position or an off position. Here, the ON position is a position closer to the right in FIG. 1, and the OFF position is a position closer to the left in FIG. In FIG. 1, the portions above the center lines of the respective valve spools 49, 56, 63 show the state where they are in the on position, and the portions below the center lines show the state where they are in the off position. Each of the valve spools 49, 56, 63 takes an off position when hydraulic pressure (pilot pressure) is applied to the control oil chambers 32c to 34c provided at the right end of each of the shift valves 32 to 34. When the pressure is released, it assumes the on position.

A first control hydraulic passage 48 branched from the line pressure supply passage 41 is connected to the control oil chamber 32c of the first shift valve 32, and the control unit 3 is connected to the first control hydraulic passage 48.
First solenoid valve 45 turned on / off by 0
(1-2 solenoid valve) is provided.

When the first solenoid valve 45 is turned on (opened), the pilot pressure in the first control hydraulic passage 48 is released, and accordingly, the pilot pressure in the control oil chamber 32c is released. The pressure is released and the valve spool 49 assumes the ON position. At this time, the hydraulic pressure in the first main hydraulic passage 42 is supplied to the servo apply chamber 26a via the servo apply passage 50,
The hydraulic pressure in the first pressure adjusting hydraulic passage 52 branched from the line pressure supply passage 41 is supplied to the control oil chamber 37 c of the first pressure adjusting valve 37 via the second pressure adjusting hydraulic passage 53. On the other hand, when the first solenoid valve 45 is turned off (closed), pilot pressure is applied to the control oil chamber 32c, and the valve spool 49 takes the off position. At this time, the hydraulic pressure in the servo apply passage 50 (servo apply chamber 26a) is drained from the drain port 51 and the second pressure-regulating hydraulic passage 53 (control oil chamber 3).
The hydraulic pressure in 7c) is drained from the drain port 54.

A second control hydraulic passage 55 branched from the line pressure supply passage 41 is connected to the control oil chamber 33c of the second shift valve 33, and the control unit 3 is connected to the second control hydraulic passage 55.
Second solenoid valve 46 which is turned on / off by 0
(2-3 solenoid valve) is provided.

When the second solenoid valve 46 is turned off, a pilot pressure is applied to the control oil chamber 33c, and the valve spool 56 is turned off.
At this time, the oil pressure in the second main oil pressure supply passage 43 becomes the first oil pressure.
The oil is supplied to the hydraulic passage 57. The hydraulic pressure in the first hydraulic passage 57 is supplied to the first branch hydraulic passage 59, the first pressure regulating valve 37, and the 3-4 clutch hydraulic passage 61 through the third hydraulic passage 61.
The power is supplied to the four clutches 24. Further, the first hydraulic passage 5
The hydraulic pressure in 7 is supplied to the third shift valve 34 via the second branch hydraulic passage 60. On the other hand, when the second solenoid valve 46 is turned on, the pilot pressure in the second control hydraulic passage 55 is released, and accordingly, the pilot pressure in the control oil chamber 33c is released, and the valve spool 56 is turned on. Take. At this time, the oil pressure in the first oil pressure supply passage 57 (3-4 clutch 24) is drained from the drain port 58.

A third control hydraulic passage 62 branched from the line pressure supply passage 41 is connected to the control oil chamber 34c of the third shift valve 34, and the control unit 3 is connected to the third control hydraulic passage 62.
Third solenoid valve 47 which is turned on / off by 0
(3-4 solenoid valve) is provided.

When the third solenoid valve 47 is turned off, a pilot pressure is applied to the control oil chamber 34c, and the valve spool 63 takes the off position.
At this time, the hydraulic pressure in the second branch hydraulic passage 60 is supplied to the second hydraulic passage 64. The hydraulic pressure in the second hydraulic passage 64 is supplied via the third branch hydraulic passage 66, the first timing valve 35, and the servo release passage 68 or the fourth hydraulic passage 64.
It is supplied to the servo release chamber 26b via the branch hydraulic passage 67, the second pressure regulating valve 38, the intermediate hydraulic passage 69, the first timing valve 35, and the servo release passage 68.
The hydraulic pressure in the servo release passage 68 is also supplied to the coast clutch 23 via the coast clutch hydraulic passage 77. The coast clutch hydraulic passage 77
Is provided with a second timing valve 36, a one-way valve 78, one-way orifices 79 and 81, and a switching valve 80. On the other hand, when the third solenoid valve 47 is turned on, the pilot pressure in the third control hydraulic passage 62 is released, and accordingly, the control oil chamber 3 is released.
The pilot pressure in 4c is released, and the valve spool 63 takes the ON position. At this time, the hydraulic supply passage 64
(Servo release chamber 26b)
Drained from

The hydraulic pressure in the 3-4 clutch hydraulic passage 61 is supplied to the control oil chamber 35c of the first timing valve 35 via the hydraulic passage 70. Further, a pilot pressure is supplied to the control oil chamber 37c of the first pressure regulating valve 37 via a hydraulic passage 71. Here, the hydraulic passage 71 is connected to the control oil chamber 38c of the second pressure regulating valve 38 via the hydraulic passage 72. The hydraulic passage 74 branched from the hydraulic passage 71 has a fourth solenoid valve 75 (N
o.5 solenoid valve).

Here, when the fourth solenoid valve 75 is turned off (closed), the first solenoid valve 75 is
The pilot pressure is supplied to the control oil chamber 37c of the pressure regulating valve 37, while the supply of the pilot pressure to the control oil chamber 37c is stopped when the fourth solenoid valve 75 is turned on (opened). I have.

With the hydraulic mechanism F, the hydraulic pressure for each friction element (the select position) of the manual valve 31 and the on / off state of the first to fourth solenoid valves 45, 46, 47, 75 are determined. The supply and discharge of hydraulic oil) are controlled so that various ranges or gears as shown in Table 1 can be obtained. Table 2 shows the first to fourth solenoid valves 45, 45 corresponding to the respective gears in the D range.
46, 47, and 75 on / off patterns are shown.

[0037]

[Table 2]

By the way, as described in the above-mentioned "Problems to be Solved by the Invention", in the conventional automatic transmission, the hydraulic pressure is released from the gear position where the hydraulic pressure is applied to the servo apply chamber, and thus the other pressures are removed. At the time of shifting to the shift speed, the hydraulic pressure in the 1-2 accumulator is rapidly released to the servo apply passage in the initial stage, and this hydraulic pressure acts on the servo apply chamber, and is released once.
The brakes were temporarily re-engaged, causing problems such as shock or hesitation.

Therefore, in this embodiment, when shifting to another gear by removing the oil pressure from the gear at which the hydraulic pressure is applied to the servo apply chamber 26a, the hydraulic pressure is basically applied to the servo release chamber 26b. By passing through the applied state, the 2-4 brake 26 is prevented from being temporarily engaged, and the occurrence of such shock or hesitation is prevented.

However, as is apparent from FIG.
To apply hydraulic pressure to the servo release chamber 26b, it is necessary to turn off the second and third solenoid valves 46 and 47 (the second and third shift valves 33 and 34). If the solenoid valves 46 and 47 are simply turned off, the hydraulic pressure is also supplied to the 3-4 clutch 24, and the 3-4 clutch 24 is engaged. Thus 3
When the -4 clutch 24 is engaged, the transmission gear mechanism 5 enters the third speed state.
Three-stage switching such as speed → 3rd → 1st speed is performed, and at the time of shifting from 2nd speed to 1st speed, three-stage switching such as 2nd → 3rd → 1st speed is performed, and the first speed state is established. The transition is delayed.

Therefore, in this embodiment, when shifting to another gear by removing the oil pressure from the gear at which the hydraulic pressure is applied to the servo apply chamber 26a, the hydraulic pressure is applied to the servo release chamber 26b and 3 (4) This problem is prevented from occurring by passing through a state in which the hydraulic pressure of the clutch 24 is released.

More specifically, the shift from the fourth speed to the first speed, the shift from the third speed to the first speed, and the
When shifting from the first speed to the first speed, the servo apply chamber 2
When the hydraulic pressure of 6a is released, the hydraulic pressure is applied to the servo release chamber 26b and the hydraulic pressure of the 3-4 clutch 24 is released, thereby preventing the occurrence of shock or hesitation. That is, as can be seen from Table 2, the first solenoid valve 45 (the first shift valve 32) is turned on at the second, third and fourth speeds, so that the hydraulic pressure is applied to the servo apply chamber 26a. Since the first solenoid valve 45 is turned off, no hydraulic pressure is applied to the servo apply chamber 26a. Therefore, 2nd gear, 3rd gear
When shifting from the first or fourth speed to the first speed, the hydraulic pressure in the servo apply chamber 26a is released.

As shown in Table 2, the state where the hydraulic pressure is applied to the servo release chamber 26b and the hydraulic pressure of the 3-4 clutch 24 is released is as shown in Table 2. It is created by turning off (close) all 47 while turning on (opening) the fourth solenoid valve 75. That is, in this state, since the first solenoid valve 45 is turned off, the hydraulic pressure in the servo apply chamber 26a is drained (released) from the drain port 51. Also, the second and third solenoid valves 46, 4
7 is turned off, so basically 3-4 clutch 24
And the servo release chamber 26b can be supplied with hydraulic pressure.

However, the fourth solenoid valve 75
Is turned on, the pilot pressure is not supplied to the control oil chamber 37c of the first pressure regulating valve 37, and the first
Since the solenoid valve 45 is turned off, the oil pressure in the control oil chamber 37c is drained (released) through the second pressure adjusting hydraulic passage 53 and the drain port 54 of the first shift valve 32. Therefore, the first pressure regulating valve 37 is in the ON position, and the hydraulic pressure of the 3-4 clutch 24 is 3-4
Drain (release) is performed via the clutch hydraulic passage 61 and the drain port 90 of the first pressure regulating valve 37. At this time, since the first branch hydraulic passage 59 and the 3-4 clutch hydraulic passage 61 are shut off by the first pressure regulating valve 37, the 3-4 clutch 2
No hydraulic pressure is supplied to 4. Therefore, the 3-4 clutch 24 is released. It goes without saying that hydraulic pressure is supplied to the servo release chamber 26b. In this way, a state is created in which the hydraulic pressure is supplied to the servo release chamber 26b and the hydraulic pressure of the 3-4 clutch 24 is released.

As described above, in the intermediate state where the first to third solenoid valves 45 to 47 are turned off and the fourth solenoid valve 75 is turned on, the speed change gear mechanism 5 is in the first speed state. In this case, the coast clutch 23 is engaged. Therefore, when shifting to the first speed through the intermediate state from the second, third, or fourth speed, the second speed is changed to the second speed, respectively.
Switching from 1st gear → 1st gear, 3rd gear → 1st gear → 1st gear, 4th gear → 1st gear → 1st gear is performed, and the shift to the 1st gear state is quickly performed while preventing the occurrence of shock or hesitation. be able to.

[0046]

According to the present invention, when shifting to another gear by removing the oil pressure from the gear at which oil pressure is applied to the servo apply chamber, hydraulic pressure is applied to the servo release chamber, The hydraulic pressure prevents the hydraulic pressure in the accumulator from acting on the servo apply chamber, thereby preventing the occurrence of shock or hesitation and enhancing the running feeling. When shifting from the 4th speed to the 1st speed, shifting from the 3rd speed to the 1st speed, and shifting from the 2nd speed to the 1st speed, hydraulic pressure is applied to the servo release chamber when the hydraulic pressure in the servo apply chamber is released. And the hydraulic pressure of the 3-4 clutch is released, the transmission gear mechanism is in the first speed state in the intermediate state, and the transmission gear mechanism can be quickly shifted to the first speed state. Further, since the solenoid valve is opened and the pilot pressure of the pressure regulating valve is drained through the 1-2 shift valve, the hydraulic pressure of the 3-4 clutch is drained through the pressure regulating valve. Sometimes it is not necessary to separately provide a valve or the like for releasing the hydraulic pressure of the 3-4 clutch, and the hydraulic mechanism is downsized.

[0047]

[0048]

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a hydraulic mechanism of an automatic transmission according to the present invention.

FIG. 2 is a system configuration diagram of the automatic transmission according to the present invention.

[Explanation of symbols]

AT: Automatic transmission F: Hydraulic mechanism 5: Transmission gear mechanism 24: 3-4 clutch 26: 2-4 brake 26a: Servo apply chamber 26b: Servo release chamber 30: Control unit 32: First shift valve (1-2) Shift valve) 37 ... first pressure regulating valve 39 ... 1-2 accumulator 50 ... servo apply passage 68 ... servo release passage 75 ... fourth solenoid valve (No.5 solenoid valve)

Claims (1)

(57) [Claims] A transmission gear mechanism having a plurality of speed stages including first to fourth forward speeds; a plurality of hydraulic friction elements for switching the speed stages by switching power transmission characteristics within the speed change gear mechanism; A hydraulic mechanism for supplying and discharging hydraulic pressure to and from the friction element, wherein the friction element is engaged when hydraulic pressure is applied to the servo apply chamber through the servo apply passage, and is released when the hydraulic pressure is released or the servo release passage is provided. Includes a servo piston type brake that is released when hydraulic pressure is applied to the servo release chamber and a 3-4 clutch that is engaged in third and fourth speeds, and controls the supply and discharge of hydraulic pressure to the servo apply chamber. A 1-2 shift valve, a pressure regulating valve for adjusting the hydraulic pressure of the 3-4 clutch, and a solenoid valve for controlling the supply of pilot pressure to the pressure regulating valve. And, in the control device for an automatic transmission accumulator is provided for the servo apply passage, a shift from 4th speed to first speed, the shifting from the third speed to the first speed, 2
At the time of shifting from the first speed to the first speed, when the hydraulic pressure in the servo apply chamber is released, hydraulic pressure is applied to the servo release chamber,
And a shift control means for passing through a state in which the hydraulic pressure of the 3-4 clutch is released, wherein the hydraulic control means shifts from the fourth speed to the first speed, and shifts from the third speed to the first speed.
When the hydraulic pressure in the servo apply chamber is released at the time of shifting to the second speed and shifting from the second speed to the first speed, the solenoid valve is opened and the pilot pressure is drained via a 1-2 shift valve. 3. A control device for an automatic transmission, wherein a hydraulic pressure of a 3-4 clutch is drained via the pressure regulating valve.