JPS61160654A - Hydraulic control device of automatic transmission - Google Patents

Abstract

PURPOSE:To prevent generation of a speed change shock, by providing a small sized hole in a spool of a cut back valve. CONSTITUTION:A cut back valve 12 provides in its land 52b a small sized hole 52d in a radial direction connecting an external contour part with a hole 52c, and the small sized hole 52d is used as an oil path. In this way, generation of a speed change shock can be prevented even when the cut back valve 12 is switched simultaneously with a 2-3 shift valve because the small sized hole 52d performs action simular to an orifice in one-way direction.

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 An example of a conventional cut-back valve in a hydraulic control system for an automatic transmission is the cut-back valve (pressure modifier valve) shown 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 small L or N, it drains the cutback signal pressure oil passage that communicates with the cut/header port of the regulator valve, and also controls the governor pressure. In the switching position where the pressure is large, an oil passage to which a predetermined oil pressure (for example, throttle pressure) is supplied is communicated with the cut/header signal pressure oil passage. As a result, when the governor pressure is small, the regulator/(rube) regulates a high line pressure, and on the other hand, when the governor pressure becomes large and the cut-off 1<) rev is switched, a state is reached in which the regulator/(lube) regulates a 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 switches 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.

Switching of the 2-3 shift valve from the up position to the down position (3->2 shift) and 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 due to 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 and causing 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 in order to do so, a one-way orifice should be installed in the cutback signal pressure oil path. It is necessary to provide In order to provide a one-way orifice, it is necessary to secure space for it in the hydraulic control device whose size is restricted, and there is also the problem that the cost increases.The present invention solves the above problems. The purpose is to resolve the issue.

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

(e) Operation 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 path, and the regulator valve immediately becomes in a state where it regulates the low line pressure.Next, conversely, when the cutback valve switches 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.As a result, the line pressure regulated by the regulator valve also gradually increases until it reaches a predetermined level. time is required. The predetermined time required for this increase in line pressure is set longer than the shift time required for the 3-2 shift. As a result, even if a 3->2 shift and cutback/help switching occur at the same time, the line pressure will not rise until the 3->2 shift is completed, and the 3->2 shift will be performed while the line pressure remains low. Since this is completed, the 3rd to 2nd gear 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 transmits the rotational force from the engine output shaft E via the torque converter T/C. An input shaft (■), an output shaft O1 that transmits driving force to the final drive'@-, a second planetary gear Gl, and a second planetary gear set Gz.

Front clutch F/C, rear clutch R/C, bunt flake B, low and reverse brake L&R/B,
and a one-way clutch OWC. The first planetary gear set G1 includes a sun gear S1 and an internal gear R1.
and a carrier PCI that supports the pinion gear P1 that meshes with both gears S1 and 8 gears at the same time.
Further, the planetary gear set GZ includes 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. The above power transmission mechanism operates the planetary gear set G by operating the front clutch F/C, rear clutch R/C, band brake B, and low and reverse brake L&R/B (one-way clutch 0WC) in various combinations.
1 and each element of Gz (St, s, , Rs, R2, PCl
and PCz), 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. 3 shows a hydraulic control device according to the present invention, which includes an oil pump 2, a pressure regulator valve 4. Manual valve 6.1-2 shift pal: li
'8.2-3 shift valve 10, cutback valve 1
2. Vacuum throttle valve 14, throttle backup valve 16, solenoid downshift valve 1
8. Second lock valve 20, timing valve 22
, and a governor valve 24, these valves are torque converter T/C, front clutch F/C,
It is connected to the rear clutch R/C, the servo apply chamber S/A and servo release chamber S/R1 of the band brake B, and the low and reverse brake L&R/B as shown in the figure, and each friction element is controlled by the action of these valves. A predetermined hydraulic pressure is distributed to. In the following description, the cutback valve 12, which is directly related to the present invention, will be mainly explained in detail, and detailed explanations 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 Application Laid-Open No. 132082/1982.

The cutback valve 12, which is shown enlarged in FIGS. 1(a) and (b), has a port 50
A spool hole 50 having a to 50d and a spool hole 50
1, and a spring 54 that pushes the spool 52 to the right in FIG. port 5
0a communicates with the governor pressure oil passage 56, and 50b
is in communication with the throttle pressure oil passage 58, and 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.
b is provided with a small diameter hole 82d in the radial direction that communicates the outer diameter portion with the hole 52c. Land 52a and land 52
When the spool 52 moves to the right as shown in FIG. 1(a), the land 52b is located at
and the spool 5 as shown in Figure 1(b).
2 is moved to the left, the boat 50b and the port 50c are connected by a gap in the outer periphery of the small diameter shaft portion 52e between the lands 52a and 52b.

Next, the operation of this embodiment will be explained. When the 11L speed is low and the oil pressure in the governor pressure oil passage 56 is small, the spool 52 is pushed by the spring 54 and is located at the position shown in FIG. 81(a) (high pressure side position). In this state, the port 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 does not act on the drain port 50d through the small diameter hole 52d of the spool 52 and the cutback port 62 of the regulator valve 4. The line pressure regulated by the regulator valve 4 is in a high state. From this state, the vehicle speed increases, and the governor pressure oil passage 56
When the oil pressure increases to a predetermined value, the spool 52 is switched against the force of the spring 54 to the position shown in FIG. 1(b) (low pressure side position). This will cause port 5
0b and the port 50c communicate with each other, and the throttle pressure oil passage 58
hydraulic pressure is supplied to the cutback signal pressure oil path 6O. 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 connection between the port 50b and the port 50C is the small diameter shaft portion 52e of the spool 52.
Since the oil pressure in the oil passage 58 immediately acts on the cutback port 62 of the regulator valve 4 via the cutback signal pressure oil passage 60, Change the pressure regulation state of valve 4. That is, as soon as the cutback valve 12 is switched, the line pressure becomes low. Conversely, when the oil pressure in the governor pressure oil passage 56 decreases from this state, the spool 52 returns to the state shown in FIG. 1 (&). 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. This is because the cross-sectional area of the small diameter hole 52d is small.

Due to the throttling effect, it takes a considerable amount of time for the oil pressure in the cutback signal pressure oil passage 60 to be discharged. 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 of the cutback port 62 is maintained is set to be longer than the shift time required for 3->2 shift. Therefore, 2-
Even if the 3rd shift valve lO 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 has a lower oil pressure. is maintained in a state where the pressure is regulated. Therefore, the 3rd to 2nd gear shift is performed under stable and low line pressure, and no excessive shift shock occurs. In this way, the cutback valve 12 is connected to the cutback signal pressure oil passage 60. It has a function similar to that of a one-sided orifice, in which when hydraulic pressure is supplied, the hydraulic pressure is rapidly supplied, and conversely, when the hydraulic pressure in the cutback signal pressure oil passage 60 is discharged, a throttling effect is produced and the hydraulic pressure is discharged slowly. However, there is no need to provide a special one-sided orifice for this purpose, and it is only necessary to provide a small diameter hole 52d in the spool 52, so the space required does not increase, and the price is lower than when installing a one-sided orifice. can be reduced.

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 acts on the cutback port. The present invention can also be applied to such types of devices. In this case, the hydraulic pressure may be supplied to the cutback port of the insulator valve through the small diameter hole of the spool of the cutback valve.

(G) As described in detail, 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-sided orifice, so that the cutback valve can be Even when switching at the same time as the 3rd shift valve, it is possible to prevent shift shifting and slippage from occurring.
Moreover, it is possible to obtain the effect that the required space and price do not increase due to this.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a cutback valve according to the present invention ((
(a) is when the spool is in the high pressure side position, (b) is when the spool is in the low pressure side position), Figure 2 is a skeleton diagram of the automatic transmission, and Figure 3 is a diagram showing the entire hydraulic control device. . 4..O regulator valve, 12.. cutback valve, 50. ... Spool hole, 52 ... Spool, 54 ... Fist spring, 56 Fist ... Governor pressure oil path, 5
8...Fist throttle pressure oil line, 60@+11+power back signal pressure oil line.

Claims (1)

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