JPS61286656A - Oil pressure control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent a speed-change-shock at the time of 3 2 speed change by providing a one-way orifice to an oil passage, which is connected to a governor-pressure-acting-port of a cutback valve. CONSTITUTION:A one-way orifice 70 is provided to an entrance of a port 50a of a cutback valve 12, which is connected to a governor pressure oil passage 56. A one-way orifice 70 produces a throttling effect when the oil from the port 50a flows out to the oil passage (56) side. In addition, when the car speed drops, a spool 52 of the cutback valve 12 is switched from the upper half position to the lower half position. At this time, however, the switching of the spool 52 is delayed by a predetermined time because of the throttling effect by the one-way orifice 70. At this time, since the time required for switching the spool 52 is set in advance so that it is longer the time required for a 3 2 speed change, the 3 2 speed change is carried out under a stable low line pressure, thereby eliminating an excessive speed-change-shock.

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 of a hydraulic control device for an automatic transmission, there is, for example, a cutback valve (pressure modifier valve) disclosed in Japanese Utility Model Application Publication No. 59-7954. has a spool that switches 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, and when the governor pressure is high, it drains the cutback signal pressure oil passage that communicates with the cutback port of the regulator valve. At the switching position, 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 car/dock valve changes during a downshift and the line pressure increases, causing a large shift shock. There is a problem that this may occur. That is, under certain operating conditions.

The switching of the 2-3 shift valve from the up position to the down position (3->2 shift) 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 cut-back 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 rapidly increases, causing a large shift shock.The present invention aims to solve the above-mentioned problems.

(d) Means for Solving the Problems The present invention attempts to solve the above problems by providing a one-sided orifice close to the governor pressure boat of the cutback valve. That is, in the hydraulic control device for an automatic transmission according to the present invention, a one-sided orifice is provided in the oil passage that supplies governor pressure to the governor pressure action boat of the cutback valve. It is oriented to create a throttling effect when oil flows from the pressure boat side.

(e) When the spool of the action cutback valve is switched from the low pressure side position to the high pressure side position, the spool moves in a direction to drain oil from the governor pressure action boat. As a result, the oil in the governor pressure boat is discharged, but since a one-sided orifice is provided in the middle, the spool moves slowly due to its throttling effect. Therefore, 2
Even if conditions are such that the switching of the -3 shift valve in the 3-2 direction and the switching of the cutback valve start at almost the same time, the switching of the cutback valve will be similar to that of the 2-3 shift valve. It can be sent for a predetermined amount of time rather than switching. Therefore, the line pressure increases after the 3rd to 2nd shift is completed. With the line pressure still low like this, 3→2
Since the shift is completed, the 3rd to 2nd shift is stable and no excessive shift shock occurs. Furthermore, when the cutback valve spool is switched from the high pressure side position to the low pressure side position, the governor pressure is applied. Oil flows into the boat, but in this case, the one-sided orifice does not have a throttling effect, so it switches at the normal timing, and no harm is caused by the one-sided orifice.

(F) Embodiments Below, an embodiment of the present invention will be described with reference to FIGS. 1 to 4 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 transmits the rotational force from the engine output shaft E via the torque converter T/C. Input shaft I, output shaft 0 that transmits driving force to the final drive device, first planetary gear set G1, second planetary gear set CZ, front clutch F/C, rear clutch R/
C, bunt flake B, low and reverse brake L
&R/B, and one-way clutch OWC. The first planetary gear set G1 is composed of a sun gear SI, an internal gear R, and a carrier PC that supports a binion gear P1 that meshes with both gears S1 and R1 at the same time. , an internal gear R2, and a carrier PC2 that supports a binion gear P2 that meshes with both gears S2 and R2 at the same time. Each component is connected as shown. The above power transmission mechanism is a front clutch F/C
, rear clutch R/C, band brake B and low and reverse brake L&R/B (one-way clutch 0
WC) in various combinations, each element (S+, Sz, R1, R
Z, 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 three forward speeds and one reverse speed.

FIG. 1 shows a hydraulic control device according to the present invention, which includes an oil pump 2. Pressure regulator valve 4, manual valve 6.1-2 shift valve 8.
2-3 Shift valve lO, cutback valve 12. Vacuum throttle valve 14, throttle backup valve 16, solenoid downshift valve 18, second lock valve 20. The timing valve 22 and governor valve 24 are controlled, and these valves are connected to the servo apply chamber S of the torque converter T/C, front clutch F/C, rear clutch R/C, and band brake B.
/A, servo release IS/R1, 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 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 the parts whose explanations are omitted are the same as those disclosed in, for example, Japanese Patent Laid-Open No. 132062/1983.

The cutback valve 12 shown in FIG.
It has a spool hole 5o having a diameter of 50d, a spool 52 inserted into the spool hole 50, and a spring 54 that pushes the spool 52 to the right in FIG. boat 50
a communicates with the governor pressure oil passage 56, and BO) 50b communicates with the throttle pressure oil passage 58, BO) 50c.
is in communication with the cutback signal pressure oil passage 60, and the boat 50d is a drain boat. The cutback signal pressure oil passage 60 communicates with a cutback boat 62 of the pressure regulator valve 4. The spool 52 includes a land 52a and a land 52b having a slightly smaller diameter.
have. The positional relationship between the land 52a and the land 52b is as shown in the upper half of FIG. As shown in the lower half of Figure 1, when the spool 52 is moved to the right, the communication between the boats 50b and 50c is through the land 52.
b and the boat 50c is blocked by the boat 50.
The positional relationship is such that it communicates with d. As mentioned above
50a communicates with the governor pressure oil passage 56,
A one-way orifice 70 is provided at the entrance of this boat 50a. The one-way orifice 70 is, for example, of the type in which a small hole 72 is provided in a leaf spring 71, and when the oil in the bow 50a flows out to the oil path 56 side, a throttling effect is generated, and conversely, the oil in the bow 50a is It is arranged in an orientation that does not have a throttling effect when flowing in.

Next, the operation of this embodiment will be explained. When the vehicle speed is low and the governor pressure in the oil passage 56 is low, the spool 52 is pushed by the spring 54 and is located at the position shown in the lower half of FIG. 1 (high pressure side position). In this state, the bow 50b is sandwiched between the lands 52a and 52b, so the oil pressure in 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
Since the oil is discharged to 0d, no hydraulic pressure acts on the cutback boat 62 of the pressure regulator valve 4. Therefore, the line pressure regulated by the pressure regulator valve 4 is in a high state.

From this state, when the vehicle speed increases and the governor pressure in the oil passage 56 rises to a predetermined value, the spool 52 moves toward the upper half in FIG. 1 against the force of the spring 54 and the throttle pressure acting on the boat 50b. Switches to the position shown (low pressure side position). As a result, the boat 50b and the boat 50c communicate with each other, and the oil pressure in the throttle pressure oil path 58 is supplied to the cutback signal pressure oil path 60, so oil pressure acts on the cutback boat 62 of the pressure regulator valve 4.
The pressure regulator valve 4 is in a state of regulating low line pressure. Cutback valve 1 as above
When the spool 52 of No. 2 is switched from the state shown in the lower half of FIG. 1 to the state shown in the upper half of FIG. 1, oil flows into the boat 50a, which is a governor pressure boat. In this case, the leaf spring 71 of the one-way orifice 70 is elastically deformed to open the passage and has no throttling effect, so the spool 52 can be switched at the normal speed.

Next, when the vehicle speed decreases from this state, the spool 52 of the cutback valve 12 switches again from the position shown in the upper half of FIG. 1 to the position shown in the lower half. It is delayed by a predetermined time as follows. That is, when the spool 52 moves as described above, oil is discharged from the boat 50a into the oil path 56. This flow of oil is resisted by the throttling effect of the one-way orifice 70 (ie, the oil flows through the eyelet 72), so it takes some time for the spool 52 to move. The time required to switch the spool 52 is 3→
This is set to be longer than the shift time required for second shift. Therefore, even if the conditions are such that the 2-3 shift valve 10 and the car/drive pack valve 12 start switching at the same time, there is no oil pressure in the cutback boat 62 of the pressure regulator valve 4 until the 3-2 shift is completed. The operating state is maintained, and the pressure regulator valve 4 is maintained in a state of regulating low oil pressure. For this reason,
Shifting from 3 to 2 is performed under stable, low line pressure, and no excessive shift shock occurs.

Note that the leaf spring 71 of the one-way orifice 70 can be provided as shown in FIG. 3, for example. That is, when the spool hole 52 of the cutback valve 12 is covered by the side plate 80 and the governor pressure oil passage 56 is provided in the side plate 80, the leaf spring 71 is attached to the side plate 80 as shown in FIG. By attaching it in this manner, a one-way orifice 70 can be configured.

Additionally, the one-way orifice 70 can be configured as shown in FIG. That is, a separate plate 92 is sandwiched between the valve body 90 and the side plate 80, a passage hole 94 is provided therein, and a leaf spring 71 is attached to the one-way orifice 70.
Configure.

(G) As described in detail, according to the present invention, a one-way orifice is provided in the oil passage communicating with the governor pressure acting port of the car/dock pack valve, so that the cutback valve can
Even if switching is started at the same time as the 3rd shift valve, the line pressure is increased after the 3rd to 2nd shift is completed, and it is possible to prevent an excessive shift shift from occurring.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a hydraulic circuit including a hydraulic control device for an automatic transmission according to the present invention, FIG. 2 is a schematic diagram of the automatic transmission, and FIG.
The figure shows one example of a one-way orifice, and FIG. 4 shows another example of a one-way orifice. 4...Regulator valve, 12-Φ cutback valve, 52...Spool, 54...Spring,
56... Governor pressure oil passage, 60... Cutback signal pressure oil passage, 70... One-way orifice.

Claims (1)

[Claims] The line pressure regulation state of the regulator valve is controlled by switching the supply and discharge of cutback signal hydraulic pressure to and from the regulator valve using the cutback valve, and the spool of the cutback valve is provided with at least a governor corresponding to the vehicle speed. In a hydraulic control device for an automatic transmission configured to apply pressure-based force, a one-way orifice is provided in the oil passage that supplies governor pressure to the governor pressure application port of the cutback valve. A hydraulic control device for an automatic transmission, characterized in that the cutback valve is oriented to generate a throttling effect when oil flows from the governor pressure acting port side.