JPS61270545A - Hydraulic controller for automatic transmission - Google Patents

Abstract

PURPOSE:To enable setting of the hydraulic pressure at desired level by arranging a reducing valve in the oil chamber of clutch while synchronizing the hydraulic pressures in the servo-release chamber and the clutch oil chamber. CONSTITUTION:The line pressure in the oil path 58 is fed to the ports 52a, 52d of reducing valve 50. Consequently, the spool 54 of the reducing valve 50 is brought to the pressure regulating position thus to reduce the hydraulic pressure at the port 52e by predetermined level corresponding with the spring 56 force from the hydraulic pressure at the port 52a. As a result, the torque capacity of front clutch F/C can be set to desired level irrespectively of the hydraulic pressure in the servo-release chamber S/R.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a hydraulic control device for an automatic transmission.

(B) Prior Art A conventional hydraulic control system for an automatic transmission is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-144338. The automatic transmission shown here has a planetary gear train with three forward speeds, and gear shifting is performed by switching the rotational state of this gear using a plurality of clutches and brakes. During the 2-3 gear shift, the front clutch is engaged and the band brake, which had been engaged until then, is released. For this purpose, hydraulic pressure is supplied from the 2-3 shift valve to the oil chamber of the front clutch and the servo release chamber of the band brake. A pressure reducing valve is provided between the 2-3 shift pulp and the oil chamber of the front clutch, so that the reduced pressure is supplied to the oil chamber of the front clutch. The pressure reducing valve is configured to always output a constant hydraulic pressure.

(c) Problems to be Solved by the Invention The pressure reducing valve as described above supplies hydraulic pressure to the oil chamber of the front clutch and the servo release chamber of the band brake as shown by broken lines and solid lines in FIG. 6, respectively. That is, the oil pressure in the servo release chamber has a region where it remains approximately constant during the stroke of the piston, and then, as the piston stroke ends, the oil pressure rapidly increases by -1- and the band brake is released. On the other hand, the oil pressure in the oil chamber of the front clutch initially rises by -L like the oil pressure in the servo release chamber, but once it reaches a certain value, it does not rise beyond that point.

At this time, the constant value for regulating the pressure of the pressure reducing valve is set so that the torque capacity of the front clutch is appropriate. However, when such a pressure reducing valve is used, there is a problem in that it is difficult to adjust the timing of engagement of the front clutch and release of the band brake. In other words, the oil pressure in the front clutch's oil chamber reaches a predetermined constant value relatively early and engagement is performed, whereas the oil pressure in the band brake's servo release chamber rises later than this, resulting in a delay in release. Become. This is because the oil pressure in the oil chamber of the front clutch is controlled to a constant value regardless of the oil pressure in the servo release chamber of the band brake. In addition, when such a pressure reducing valve is used, the oil pressure in the oil chamber of the front I/clutch is maintained at this constant oil pressure even after the gear shift is completed, so for example, in the third gear state, full throttle is applied and a large torque is generated. When this occurs, the front clutch may slip in some cases. The present invention aims to solve the problems mentioned in L.

(d) Means for Solving the Problems The present invention attempts to solve the above problems by using a pressure reducing valve that always outputs a hydraulic pressure that is subtracted by a fixed value from the supplied hydraulic pressure. be. That is,
In the hydraulic control device for an automatic transmission according to the present invention, the hydraulic pressure from the shift valve is directly supplied to the servo release chamber of the band brake, and the hydraulic pressure reduced by the pressure reducing valve is supplied to the oil chamber of the clutch. The gist is that the system is configured to output hydraulic pressure obtained by subtracting a certain value corresponding to the spring force from the hydraulic pressure from the shift valve.

(E) Operation When the shift valve is switched, hydraulic pressure is supplied to the oil chamber of the clutch and the servo release chamber of the band brake. Line pressure is directly supplied to the servo release chamber of the band brake from the shift valve. On the other hand, the hydraulic pressure reduced by the pressure reducing valve is supplied to the oil chamber of the clutch. The pressure reducing valve outputs oil pressure by reducing the line pressure supplied from the shift valve by a fixed value depending on the spring force.
This is sent to the servo release room. This allows for example the third
Hydraulic characteristics as shown in the figure are obtained. Since the hydraulic pressure in the servo release chamber of the band brake and the hydraulic pressure in the clutch oil chamber change at the same timing as shown in Figure 3, it is possible to synchronize the release of the band brake and the engagement of the clutch. . Furthermore, since the torque capacity of the clutch can be adjusted by selecting the spring of the pressure reducing valve, it is easy to set the torque capacity to be optimal during gear shifting. Further, after the shift is completed, the oil pressure increases higher than the oil pressure during the shift, so that sufficient torque capacity can be ensured even in a steady state.

(F) Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5 of the accompanying drawings.

(First Embodiment) FIG. 2 shows a schematic diagram of a power transmission mechanism of an automatic transmission with three forward speeds and one reverse speed. This power transmission mechanism consists of an input shaft (■) to which rotational force from the engine output shaft E is transmitted via a torque converter T/C, an output shaft (0) and a first i4I? which transmit driving force to the final drive device. , gear set G1, second
It has a planetary gear set G2, a front clutch F/C, a rear clutch R/C, a band brake B, a low and reverse brake L&R/B, and a one-way clutch OWC. The first planetary gear set G1 is a sun gear S.

, a carrier PC that supports internal gear R1, and binion gear P1 that meshes with both gears S1 and R1 at the same time.
, and the planetary gear set G2 is composed of a sun gear S2, an internal gear R2, and a carrier PC2 that supports a pinion gear P2 that meshes with both gears Sz and RZ at the same time. Each component is connected as shown. -11 The power transmission mechanism operates the planetary gear set G1 and Each element of Gz (S
+, Sz, R1, R2, PCl and PCz) can be changed, thereby changing the rotational speed of the output shaft 0 relative to the rotational speed of the input shaft load to obtain 3 forward speeds and 1 reverse speed. .

FIG. 1 shows a hydraulic control device according to the present invention. This hydraulic control device includes an oil pump 2, a pressure regulator valve 4, a manual valve 6.1-2 a shift valve 8.
2-3 Shift Palf lO, Cutback Valve 12, Vacuum Throttle Valve 14, Throttle Backup Valve 16, Solenoid Town Shift Valve 7'18,
Second lock valve 20, timing valve 221,
Governor valve 24. and a pressure reducing valve 50,
These valves are torque converter T/C, front clutch F/C, rear clutch R/C, band brake B
Servo apply chamber S/A and servo release chamber S/R
1 and low and reverse brake L&R/B as shown in the figure, and a predetermined hydraulic pressure is distributed to each friction element by the action of these valves. In the following description, the pressure reducing valve 50 that is directly related to the present invention will be mainly described in detail, and detailed description of other valves will be omitted. The structure and operation of parts whose explanations are omitted can be found in, for example, Japanese Patent Application Laid-Open No. 1983-1999. -13206
This is similar to that disclosed in Publication No. 2.

The pressure reducing valve 50 shown in FIG.
and a spool 5 inserted into the valve hole 52.
4, and a spring 56 that pushes the spool 54 in one direction in FIG. The ports 52a and 52d communicate with the oil passage 58. The oil passage 58 is an oil passage to which line pressure is supplied when the 2-3 shift valve 10 is in the up position, that is, the third gear position, and this oil passage 58 also communicates with the servo release chamber S/R. There is. Boat 52b is a drain boat. Boats 52c and 52e communicate with oil passage 60. The oil passage 60 is the front clutch F/
It is connected to the oil chamber 62 of C. Note that orifices 64 and 66 are provided at the entrances of ports 52a and 52e, respectively. Spool 54 has two lands 54a and 54b, the axial dimension of the groove therebetween being approximately equal to the dimension between boat 52b and ports 1-52d.

Next, the operation of this embodiment will be explained. When the 2-3 shift valve 10 is switched from the second speed position to the third speed position, line pressure is supplied to the oil passage 58.

The m path 5B (1) line pressure acts on the servo release chamber S/R of the band brake B, gradually increasing the oil pressure in the servo release chamber S/R, and releasing the band brake B. The change in the oil pressure in the servo release chamber S/R at this time is shown by the solid line in FIG.

On the other hand, the line pressure of the oil passage 58 is
2a and 52d. As a result, the pressure reducing valve 5
0, the spool 54 is in the pressure regulating position as shown in FIG. 56 is in balance with the force acting upwardly on the spool 54. Therefore, the oil pressure of the boat 52e (that is, the oil pressure of the oil passage 60) is
This value is lower than the oil pressure of the port 52a (that is, the oil pressure of the oil passage 58) by a certain value corresponding to the force of the spring 56. The oil pressure of this oil passage 60 is the front Clara) F/C oil chamber 6
2 and conclude this. Changes in the oil pressure in the oil chamber 62 at this time are shown by broken lines in FIG. That is, the oil pressure in the oil chamber 62 changes at the same timing as the oil pressure in the servo release chamber S/R, and is always lower by a constant value ΔP. The oil pressure value P1, which remains almost constant during gear shifting, is set so that the torque capacity of the Freon clutch F/C is optimized. Therefore, the release of the band brake B and the engagement of the front clutch F/C are performed at the same timing, and the torque capacity of the front clutch F/C is maintained at the desired level regardless of the hydraulic pressure of the servo release chamber S/R. Can be set to a value. Therefore, desired 2-3 speed shifting performance can be obtained.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention. In this second embodiment, the pressure reducing action of the pressure reducing valve 50 is stopped when the automatic transmission is in reverse motion.

This pressure reducing valve 50 has ports 52m and 52n in addition to the ports 52a to 52e shown in FIG. port 5
2 m is in communication with the oil passage 70. The oil passage 70 is an oil passage to which line pressure is supplied when the manual valve 6 is in the R range (reverse range). Port 52n is a drain port. The diameters of the ends 54c and 54d of the spool 54 are the same.

In the case of this second embodiment, when no oil pressure is supplied to the oil passage 70, the same effect as in the first embodiment shown in FIG. 1 can be obtained. However, when the manual valve 6 is selected to the R range, the line pressure is not supplied to the oil passage 70, and the
Hydraulic pressure acts on 52m. Therefore, the downward force acting on the spool 54 in FIG. 4 becomes larger, and the spool 54 is pressed downward against the spring 56.
The pressure regulating function is lost, and a state is established in which baud) 52d and baud) 52c are communicated. Therefore, the oil passage 58 and the oil passage 60 communicate with each other, and the oil pressure of the oil passage 58 directly acts on the oil chamber 62 of the front clutch F/C via the oil passage 60. In this way, in the R range, the pressure reducing valve 50 does not have a pressure reducing effect, so
High oil pressure acts on the oil chamber 62, and the front clutch F/C
torque capacity increases. The reason why the pressure regulating action of the pressure reducing valve 50 is stopped in the R range is that in the R range, there is no need to adjust the shift timing, but rather a large torque capacity of the front clutch F/C is required.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention. Which third embodiment has an oil passage 8 in place of the oil passage 70 of the second embodiment shown in FIG.
0 to baud) 52m. The oil passage 80 is in a kicked down state when the manual valve 6 is in the R range or even when the manual valve 6 is in the D range, that is, the solenoid downshift valve 18 is in the state shown in the left half of FIG. This is the oil path to which hydraulic pressure is supplied. Therefore, in this third embodiment, the pressure reducing action of the pressure reducing valve 50 can be stopped not only in the case of the R range but also during kickdown. The reason why the pressure reducing action of the pressure reducing valve 50 is stopped even during kickdown is because during kickdown, the throttle is fully open and the torque is large, and the vehicle speed during gear shifting is also high, so a large torque capacity is required. be.

(g) As described in detail, according to the present invention, a pressure reducing valve is provided in the oil chamber of the clutch for supplying hydraulic pressure that is lower than the hydraulic pressure in the servo release chamber of the band brake by a certain value. It becomes possible to synchronize the oil pressure in the servo release chamber of the band brake and the oil pressure in the oil chamber of the clutch, and to set the oil pressure in the clutch oil chamber to a desired value.

In this way, it is possible to optimize the shift timing and set the torque capacity of the clutch to an appropriate value, thereby improving shift performance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a hydraulic circuit according to a first embodiment of the present invention, and FIG.
3 is a diagram showing the hydraulic characteristics obtained by the present invention, FIG. 4 is a diagram showing the second embodiment of the present invention, and FIG. 5 is a diagram showing the hydraulic characteristics obtained by the present invention. FIG. 6, which is a diagram showing the third embodiment, is a diagram showing hydraulic characteristics of a conventional hydraulic control device for an automatic transmission. F/C...Freon l-clutch, B--band brake, S/R---servo release chamber, 50...pressure reducing valve.

Claims (1)

[Scope of Claims] 1. A hydraulic control device for an automatic transmission having a gear shifting operation in which oil pressure from a shift valve is simultaneously supplied to an oil chamber for engaging a clutch and a servo release chamber for releasing a band brake, comprising: a band brake; Hydraulic pressure from the shift valve is directly supplied to the servo release chamber of the clutch, and hydraulic pressure reduced by a pressure reducing valve is supplied to the oil chamber of the clutch. A hydraulic control device for an automatic transmission, characterized in that it is configured to output hydraulic pressure with a reduced value. 2. The pressure reducing action of the pressure reducing valve is prevented by the hydraulic pressure output when the reverse state of the automatic transmission is selected;
2. A hydraulic control system for an automatic transmission according to claim 1, wherein the hydraulic pressure from the shift valve is directly supplied to the oil chamber of the clutch. 3. According to claim 1 or 2, the pressure reduction state of the reduction valve is prevented by the hydraulic pressure output at the time of kickdown of the automatic transmission, and the hydraulic pressure from the shift valve is directly supplied to the oil chamber of the clutch. Hydraulic control device for automatic transmission.