JPH0143183B2 - - Google Patents

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 As a conventional hydraulic control device for an automatic transmission, for example, a cutback valve (pressure modifier valve) disclosed in Japanese Utility Model Application No. 59-7954 is used.
There are some that have This cutback valve has a spool that is switched depending on the governor pressure, and in the switching position when the governor pressure is low, it drains the cutback signal pressure oil passage that communicates with the cutback port of the regulator valve. In the switching position when the governor pressure is high, the oil passage to which a predetermined oil pressure (eg, throttle pressure) is supplied is communicated with the cutback signal pressure oil passage. As a result, when the governor pressure is low, the regulator valve regulates high line pressure, and when the governor pressure increases and the cutback valve is switched, the regulator valve regulates low line pressure. Thereby, a line with predetermined characteristics depending on the operating conditions can be obtained.

(c) Problems to be Solved by the Invention However, in the conventional hydraulic control device of an automatic transmission as described above, the cutback valve is switched during downshifting and line pressure increases, causing a large shift shock. There is a problem that this may occur. That is, under certain operating conditions, 2
- The switching of the 3rd shift valve from the up position to the down position (3→2 shifting) and the switching of the cutback valve from the low pressure side position to the high pressure side position occur simultaneously. In this case, a predetermined shift time is required from the switching of the 2-3 shift valve to the completion of the 3->2 shift, but the change in line pressure due to the cutback valve takes place within a short period of time. During the 3rd to 2nd gear shift, the line pressure changes and the capacity of the friction element increases rapidly, causing a large shift shock. The present invention aims to solve the above problems.

(d) Means for solving the problem The present invention solves the above problem by always maintaining the pressure regulation state of the regulator valve at a low pressure state until the 3-2 shift is completed. be. That is, the hydraulic control device for an automatic transmission according to the present invention detects switching of the third-speed friction element,
A control means is provided to maintain the line pressure regulated by the regulator valve at a low state until this substantial switching occurs.

(E) Action While the vehicle is running in third gear, the regulator valve is in a low pressure regulating state. If the vehicle speed decreases in this state, the regulator valve will enter a high pressure regulation state, but the low pressure regulation state will be maintained until the switching of the 3rd gear friction element is completed, so the line pressure will inevitably increase. This will be performed after the 3-2 gear shift is completed. Therefore, with the line pressure still low, 3-
Since 2-shift is performed, the 3-2 shift is stable and no excessive shift shock occurs.

(F) Embodiments Hereinafter, embodiments of the present invention will be described with reference to Nos. 1 and 2 of the attached drawings.
This will be explained based on the diagram.

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 includes an input shaft I to which rotational force from an engine output shaft E is transmitted via a torque converter T/C, an output shaft O to transmit driving force to a final drive device, a first planetary gear set G 1 , a first planetary gear set G 1 , and a first planetary gear set G ₁ . 2 planetary gear set G ₂ , front clutch F/C, rear clutch R/C, band brake B, low and reverse brake L
&R/B, and one-way clutch OWC. The first planetary gear set G ₁ includes a sun gear S ₁ ,
Carrier supporting internal gear R ₁ and binion gear P ₁ that meshes with both gears S ₁ and R ₁ at the same time
Consists of PC ₁ and planetary gear set G ₂
is sun gear S ₂ , internal gear R ₂ , and pinion gear P ₂ that meshes with both gears S ₂ and R ₂ at the same time.
Supports Carrier PC ₂ .
Each component is connected as shown. The above power transmission mechanism operates the planetary gear set _G1 and Each element of G ₂ (S ₁ ,
S ₂ , R ₁ , R ₂ , PC ₁ and PC ₂ ) can be changed, thereby changing the rotation speed of the output shaft O relative to the rotation speed of the input shaft I, resulting in three forward speeds and one reverse speed. can be obtained.

FIG. 1 shows a hydraulic control device according to the present invention. This hydraulic control device includes an oil pump 2, a regulator valve 4, a manual valve 6, a 1-2 shift valve 8, a 2-3 shift valve 10, a cutback valve 12, a vacuum throttle valve 14,
Throttle backup valve 16, solenoid downshift valve 18, second lock valve 20, timing valve 22, governor valve 2
4, and a cutback timing valve 26, these valves are connected to the torque converter T/C, front clutch F/C, rear clutch R/C, servo apply chamber S/A of band brake B, and servo release chamber S. /R 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 cutback valve 12 and the cutback timing valve 26, which are directly related to the present invention, will be mainly explained in detail, and detailed explanation of other valves will be omitted. The structure and operation of the parts whose explanation is omitted are the same as those disclosed in, for example, Japanese Patent Application Laid-Open No. 132062/1983.

The cutback valve 12 has ports 50a to 5.
0d, the spool 52 inserted into the spool hole 50, and the spool 52 inserted into the first
It consists of a spring 54 that pushes rightward in the figure. The port 50a is connected to an oil passage 56 to which governor pressure corresponding to the vehicle speed is supplied. The port 50b is connected to an oil passage 58 (main pressure oil passage for cutback control) to which throttle pressure is supplied from the throttle valve 14. The port 50c is connected to an oil passage 60 (first oil passage). port 5
0d is a drain port. The spool 52 is located at a position where port 50b and port 50c communicate with each other (upper half position in FIG. 1), and at a position where port 50b is blocked and port 50c is drained to port 50d (lower half position in FIG. 1). can be switched depending on the governor pressure acting on the port 50a.

The cutback timing valve 26 includes a spool hole 62 having ports 62a to 62f, a spool 64 inserted into the spool hole 62, and a spring 66 that pushes the spool 64 upward in FIG.
It has . The port 62a is connected to an oil passage 68 to which oil pressure (third speed signal pressure) is applied from the 2-3 shift valve 10 during the third speed. This oil passage 68 is connected to the servo release chamber S/R. The port 62b is connected to the oil passage 60 described above. The port 62c is connected to a port 70 (cutback port) of the regulator valve 4 via an oil passage 69 (second oil passage). port 6
2d is the aforementioned oil passage 58 to which the throttle pressure is supplied.
is connected to. The port 62d is connected to the aforementioned oil passage 58 to which throttle pressure is supplied.
Port 62e is a drain port. port 6
2f is connected to an oil passage 72 to which hydraulic pressure is supplied when the annular valve 6 is in the R range (reverse range). The spool 64 has lands 64a, 64
b and 64c, and there is a position where ports 62b and 62c communicate with each other (left half position in Figure 1) and a position where ports 62c and 62d communicate with each other (right half position in Figure 1). ) and can be switched between. Note that the land 64c is the land 64c.
The diameter is larger than that of a and 64b.

The regulator valve 4 controls the oil pressure of the oil passage 74 to which oil discharged from the oil pump 2 is supplied to the oil passage 58.
It has a basic function of adjusting the pressure according to the throttle pressure acting on the port 76 from the throttle pressure. The regulator valve 4 is in a low pressure regulating state when oil pressure is applied to the port 70, and is in a high pressure regulating state when no oil pressure is acting on the port 70.

Next, the operation of this embodiment will be explained. 1st
When in second gear, no oil pressure is supplied to the oil passage 68, so no oil pressure is applied to the port 62a of the cutback timing valve 26, and the spool 64 is pushed by the spring 66 to the left half position in FIG. be. Therefore, port 62c and port 62b
The oil passages 60 and 69 are in a connected state. Therefore, port 7 of regulator valve 4
The oil pressure of 0 is in a state controlled by the cutback valve 12 via the oil passage 69 and the oil passage 60. When the governor pressure acting from the oil passage 56 to the port 50a is low, the spool 52 is in the lower half state in FIG.
Since the oil is discharged at 0d, no hydraulic pressure acts on the port 70 of the regulator valve 4. Therefore, the regulator valve 4 is in a high pressure regulating state. on the other hand,
When the vehicle speed increases and the governor pressure acting on the port 50a increases, the spool 52 switches to the upper half position in FIG. 60. Therefore, the throttle pressure acts on the boat 70 of the regulator valve 4, and the regulator valve 4 enters a low pressure regulating state. Therefore, as in the prior art, the line pressure is high when the vehicle speed is low, and the line pressure is low when the vehicle speed is above a predetermined speed.

When the 2-3 shift valve 10 is switched to the third speed state, hydraulic pressure is supplied to the oil passage 68. Therefore, hydraulic pressure acts on the port 62a of the cutback timing valve 26, and the spool 64 is switched to the state shown in the right half of FIG. Therefore, the port 62c and the port 62d communicate with each other, and the throttle pressure of the oil passage 58 is supplied to the oil passage 69. As a result, throttle pressure always acts on the port 70 of the regulator valve 4 during third gear.
The regulator valve 4 enters a low pressure regulating state.

If the vehicle speed decreases while driving in 3rd gear and the cutback valve 12 switches to the lower half position before the 2-3 shift valve 10 switches to the 2nd gear position, the following An operation like this is performed. That is, when the governor pressure in the oil passage 56 decreases due to a decrease in vehicle speed and the spool 52 of the cutback valve 12 is switched to the lower half position in FIG. is drained. However, when the 2-3 shift valve 10 is in the third speed position (upper half position), oil pressure is supplied to the oil passage 68, so the spool 64 of the cutback timing valve 26 is Located in the right half position. Therefore, even if the oil pressure in the oil passage 60 is discharged, the throttle pressure is supplied to the port 70 of the regulator valve 4 from the oil passage 58 through the oil passage 69, so that the regulator valve 4 can regulate the low pressure. held in state. That is, as long as it is in the third speed state, the regulator valve 4 is in a low pressure regulating state and is not affected by the state of the cutback valve 12. When the 2-3 shift valve 10 is switched to the second speed position (lower half position) in this state, the oil pressure supplied to the servo release chamber S/R via the oil passage 68 gradually decreases, and the band brake is engaged and enters the second gear state. At the same time, the hydraulic pressure acting on the port 62a of the cutback timing valve 26 is removed, so the spool 64 is switched to the left half position. Therefore, the oil passage 60 and the oil passage 69 communicate with each other, and the hydraulic pressure that was acting on the port 70 of the regulator valve 4 is discharged to the port 50d of the cutback valve 12 via the oil passage 69 and the oil passage 60. Ru. As a result, the regulator valve 4 enters a high pressure regulating state in which the high line pressure is regulated. That is, after the 3-2 gear shift is performed, the line pressure is immediately switched to a high state. In this way, the increase in line pressure always takes place after the 3-2 shift, so
-2nd gear shifting is performed under stable and low line pressure,
No excessive shift shock occurs.

Note that if the 2-3 shift valve 10 is switched to the second speed side before the cutback valve 12 is switched, the port 70 of the regulator valve 4 is Since the hydraulic pressure of the pump is controlled by the cutback valve 12, when the cutback valve 12 is switched, the regulator valve 4 is immediately switched from the low pressure regulation state to the high pressure regulation state. In this case, since the 3-2 gear shift has been performed first, even if the line pressure becomes high, it does not affect the gear shift at all.

The above operation may occur when the manual valve 6 is in the D range, but when the manual valve 6 is selected in the R range (reverse range), the line pressure is always in a high state as follows. That is, when the manual valve 6 is selected to the R range, line pressure is supplied to the oil passage 72, and this line pressure is supplied to the port 62f of the cutback timing valve 26, so that oil pressure is supplied to the port 62a. Against this, the spool 64 is always switched to the left half position. Since the land 64c of the spool 64 has a larger diameter than the land 64a, when hydraulic pressure acts on the port 62f, the spool 64 is always forced to the left half position. Therefore, the hydraulic pressure at the port 70 of the regulator valve 4 is controlled by the cutback valve 12, but since no governor pressure is generated in the R range, the spool 5 of the cutback valve 12 is controlled by the cutback valve 12.
2 is always in the lower half position in FIG. 1, and no hydraulic pressure is supplied to the oil passage 60. Therefore, no hydraulic pressure acts on the port 70, and the regulator valve 4 enters a high pressure regulation state. Therefore, in the R range, the line pressure is always in a high state.

(G) Effects of the invention As explained above, according to the present invention, 3
Since we have provided a means to detect the switching of the speed friction element and control the line pressure to maintain it in a low state until this switching occurs, the increase in line pressure when the vehicle speed decreases is always caused by 3-2 gear shifting. The 3-2 shift is carried out after the shift has been carried out, and the 3-2 shift is carried out at a predetermined low line pressure, making it possible to prevent the occurrence of an excessive shift shock.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the entire hydraulic control system to which the present invention is applied, and FIG. 2 is a skeleton diagram of an automatic transmission. 4...regulator valve, 12...cutback valve, 26...cutback timing valve, 70...cutback port.

Claims (1)

[Claims] 1. By switching the supply and discharge of hydraulic pressure to the cutback port of the regulator valve according to the vehicle speed, the line pressure regulated by the regulator valve can be adjusted at low vehicle speeds. The automatic transmission's hydraulic control system, which sometimes controls the hydraulic pressure to increase at higher vehicle speeds, detects the switching of the 3rd gear friction element and adjusts it with the regulator valve until this substantial switching occurs. 1. A hydraulic control device for an automatic transmission, comprising means for controlling line pressure to be maintained at a low state. 2 The above means is composed of a cutback valve and a cutback timing valve,
When the governor pressure corresponding to the vehicle speed is small, the cutback valve is connected to the main pressure oil passage for cutback control and the first
The cutback timing valve is switched to cut off the communication with the oil passage and to connect the main pressure oil passage for cutback control with the first oil passage when the governor pressure is high, and the cutback timing valve is discharged in the first and second speeds. Third
Switching is performed by the 3rd speed signal pressure applied at the 3rd speed.
When the speed signal pressure is not acting, the first oil passage is in the first position communicating with the second oil passage communicating with the cutback port of the regulator valve, and the position is 3.
2. The hydraulic control device for an automatic transmission according to claim 1, wherein the hydraulic pressure control device for an automatic transmission is set to a second position which communicates the cutback control source pressure oil path with the second oil path when a speed signal pressure is applied. 3. The automatic transmission according to claim 2, wherein the cutback timing valve is configured to be forcibly switched to the first position by the reverse hydraulic pressure output in the reverse range of the manual valve. Hydraulic control device.