JPH054540B2 - - 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 cutback valve for a hydraulic control device for an automatic transmission, there is, for example, a cutback valve (pressure modifier valve) disclosed in Japanese Utility Model Application No. 59-7954. 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,
An 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 to 2 shift, but the change in line pressure by the cutback valve takes place in a very short time. Therefore, during the 3rd to 2nd gear shift, the line pressure changes, causing a sudden change in the capacity of the friction element, resulting in a large shift shock. In order to prevent such problems from occurring, the line pressure should be increased after the 3rd to 2nd gear shift is completed, but to do this, a one-way orifice should be installed in the cutback signal pressure oil path. There is a need. In order to provide a one-way orifice, it is necessary to secure space for it in the hydraulic control device whose size is limited.
Another problem is that the price also increases. The present invention aims to solve the above problems.

(d) Means for solving the problems The present invention solves the above problems by using a small diameter hole provided in the spool of a cutback valve as an oil passage to achieve the same function as a one-way orifice. solve. That is, when the cutback valve according to the present invention is in the high pressure side position where the line pressure is high, the small diameter hole provided in the land of the spool forms a passage for the cutback signal hydraulic pressure, and the cutback valve is in the high pressure side position where the line pressure is high. When the spool is in the low pressure side position, a gap on the outer periphery of the small diameter shaft between the lands of the spool forms a passage for the cutback signal hydraulic pressure.

(E) Function When the cutback valve is in the high pressure side position, the cutback signal pressure oil passage is connected to, for example, a drain oil passage through the small diameter hole of the spool, and the regulator valve is in a state of regulating high line pressure. . When the cutback valve is switched to the low pressure side position from this state, throttle pressure, for example, is supplied to the cutback signal pressure oil passage through the passage on the outer periphery of the small diameter shaft portion between the lands of the spool. As a result, hydraulic pressure is rapidly supplied to the cutback signal pressure oil passage, and the regulator valve immediately enters a state in which the low line pressure is regulated. Next, when the cutback valve is switched from the low pressure side position to the high pressure side position, the cutback signal pressure oil passage is connected to the drain oil passage through the small diameter hole of the spool. The oil pressure in the cutback signal pressure oil passage gradually decreases due to the throttling effect of the small diameter hole. For this reason, the line pressure regulated by the regulator valve also gradually rises, and it takes a predetermined time for it to rise completely. The predetermined time required for this increase in line pressure is set longer than the shift time required for 3->2 shift. As a result, even if the 3rd to 2nd gear shift and the switching of the cutback valve occur simultaneously, the line pressure will not increase until the 3rd to 2nd gear shift is completed. 3→ while keeping the line pressure low
Since the second shift is completed, the third to second shift is stable and no excessive shift shock occurs.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 3 of the accompanying drawings.

FIG. 2 shows a schematic diagram of the 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 the rotational force from the engine output shaft E is transmitted via the torque converter T/C, an output shaft O to transmit the driving force to the final drive device, 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 pinion 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 ,
It is possible to change the rotational states of R ₁ , R ₂ , PC ₁ and PC ₂ , thereby changing the rotational speed of the output shaft O relative to the rotational speed of the input shaft I to obtain three forward speeds and one reverse speed. can.

FIG. 3 shows a hydraulic control device according to the present invention. This hydraulic control device includes an oil pump 2, a pressure regulator valve 4, manual valves 6 and 1.
-2 shift valve 8, 2-3 shift valve 10,
Cutback valve 12, vacuum throttle valve 14, throttle backup valve 1
6. It has a solenoid downshift valve 18, a second lock valve 20, a timing valve 22, and a governor valve 24, and these valves are used for torque conversion T/C, front clutch F/C, rear clutch R/C, and band brake B.
Servo apply chamber S/A and servo release chamber S/R, and low and reverse brake L&
It is connected to 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 directly related to the present invention will be mainly described.
will be described in detail, and a detailed description of other valves will be omitted. For the structure and operation of parts whose explanations are omitted, see, for example, Japanese Patent Application Laid-Open No. 1986-
This is similar to that disclosed in Publication No. 132062.

The cutback valve 12 is shown enlarged in FIGS. 1a and 1b. The cutback valve 12 has a spool hole 50 having ports 50a-50d, a spool 52 inserted into the spool hole 50, and a spring 54 that pushes the spool 52 to the right in FIG. Port 50a is cabana pressure oil passage 56
The port 50b communicates with the throttle pressure oil passage 58, the port 50c communicates with the cutback signal pressure oil passage 60, and the port 50d is a drain port. The cutback signal pressure oil passage 60 communicates with a cutback port 62 of the pressure regulator valve 4.
The spool 52 has lands 52a and 52b, and an axial hole 52c for receiving the spring 54 is provided inside the land 52b.
Further, the land 52b is provided with a small diameter hole 52d in the radial direction that communicates the outer diameter portion with the hole 52c. The positional relationship between the land 52a and the land 52b is such that when the spool 52 moves to the right as shown in FIG. port 50b and port 5
0c is connected to the land 52a and the land 52b by a gap on the outer periphery of the small diameter shaft portion 52e.

Next, the operation of this embodiment will be explained. When the vehicle speed is low and the oil pressure in the governor pressure oil passage 56 is low, the spool 52 is pushed by the spring 54 and is located at the position shown in FIG. 1a (high pressure side position). In this state, the port 50b is connected to the land 52.
Since the throttle pressure oil passage 58 is sandwiched between the land 52b and the land 52b, the oil pressure of the throttle pressure oil passage 58 is cut off. On the other hand, the oil pressure of the cutback signal pressure oil passage 60 is applied to the spool 52.
Since the water is discharged to the drain port 50d through the small diameter hole 52d, no hydraulic pressure acts on the cutback port 62 of the regulator valve 4. Therefore, the line pressure regulated by the regulator valve 4 is in a high state. When the vehicle speed increases from this state and the oil pressure in the governor pressure oil passage 56 rises to a predetermined value, the spool 52 is switched against the force of the spring 54 to the position shown in FIG. 1b (low pressure side position). Change. As a result, the ports 50b and 50c communicate with each other, and the throttle pressure oil passage 58
hydraulic pressure is supplied to the cutback signal pressure oil line 60. Therefore, hydraulic pressure acts on the cutback port 62 of the regulator valve 4, and the regulator valve 4 enters a state in which it regulates the low line pressure.
At this time, the port 50b and port 50c are connected through a relatively large gap between the outer periphery of the small diameter shaft portion 52e of the spool 52 and the spool hole 50, so the oil pressure in the oil passage 58 is immediately transferred to the cutback signal pressure oil passage. Regulator valve 4 through 60
It acts on the cutback port 62 to change the pressure regulation state of the regulator valve 4. That is, as soon as the cutback valve 12 is switched, the line pressure becomes low. Conversely, if the oil pressure in the governor pressure oil passage 56 decreases from this state, the spool 5
2 returns to the state shown in FIG. 1a again. As a result, the hydraulic pressure acting on the cutback port 62 of the regulator valve 4 is discharged from the cutback signal pressure oil passage 60 through the small diameter hole 52d of the spool 52 to the drain port 50d. Since the cross-sectional area of the small-diameter hole 52d is small, it takes a considerable amount of time to discharge the hydraulic pressure from the cutback signal pressure oil passage 60 due to its throttling effect. Therefore, the cutback port 62 of the regulator valve 4 is maintained in a state where hydraulic pressure is applied for a while even after the spool 52 of the cutback valve 12 is switched.
The time during which the oil pressure in the cutback port 62 is maintained is set longer than the shift time required for 3->2 shift. Therefore, the 2-3 shift valve 10
Even if the cutback valve 12 and the cutback valve 12 are switched at the same time, the oil pressure of the cutback port 62 of the regulator valve 4 is maintained until the 3rd to 2nd gear shift is completed, and the regulator valve 4 regulates the low oil pressure. held in state. Therefore, the 3rd to 2nd shift is performed under a stable and low line pressure, and no excessive shift shock occurs. In this manner, the cutback valve 12 rapidly supplies hydraulic pressure when supplying the hydraulic pressure to the cutback signal pressure oil passage 60, and conversely, when discharging the oil pressure from the cutback signal pressure oil passage 60, it produces a throttling effect and discharges the oil slowly. It has the same function as a one-way orifice. However, it is not necessary to provide a special one-way orifice for this purpose, and there is no need to provide a special one-way orifice.
Since it is only necessary to provide d, the required space does not increase, and the cost can be reduced compared to the case where a one-way orifice is provided.

Note that the regulator valve of the above embodiment is of a type in which the line pressure increases when the action of hydraulic pressure on the cutback port is released, but the line pressure increases when hydraulic pressure is applied to the cutback port. The present invention can also be applied to such types of devices. In this case, hydraulic pressure may be supplied to the cutback port of the regulator valve through a small diameter hole in the spool of the cutback valve.

(g) Effects of the Invention As explained above, according to the present invention, the spool of the cutback valve is provided with a small diameter hole to obtain the same effect as a one-way orifice, so that the cutback valve can be Even when three shift valves are switched at the same time, the occurrence of a shift shock can be prevented, and the space and cost required for this will not increase.

[Brief explanation of the drawing]

FIG. 1 shows a cutback valve according to the present invention (a is when the spool is in the high pressure side position, b is
2 is a schematic diagram of the automatic transmission, and FIG. 3 is a diagram showing the entire hydraulic control device. 4... Regulator valve, 12... Cutback valve, 50... Spool hole, 52... Spool, 54... Spring, 56... Governor pressure oil path, 58... Throttle pressure oil path, 60... Cutback signal pressure hydraulic line.

Claims (1)

[Scope of Claims] 1. In a hydraulic control device for an automatic transmission that controls the line pressure regulation state of a regulator valve by switching the supply and discharge of cutback signal hydraulic pressure to and from the regulator valve using a cutback valve. When the cutback valve is in the high pressure side position where the line pressure is high, a small diameter hole provided in the land of the spool forms a passage for the cutback signal hydraulic pressure, and when it is in the low pressure side position where the line pressure is low. 1. A hydraulic control device for an automatic transmission, characterized in that when the spool is in position, a passage for cutback signal hydraulic pressure is formed by a gap on the outer periphery of a small diameter shaft between lands of a spool.