JPH08210484A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE: To reduce a shift shock by connecting a drain oil path of discharging line pressure oil into a line pressure supply oil path, and providing in series a drain valve, opened only when fully closed a throttle opening, and a switch valve, closed when increased a governor pressure to a prescribed value or more, in the drain oil path. CONSTITUTION: In the halfway of a supply oil path 30 of line pressure PL between a regulator valve and a manual valve, drain oil path 31 is connected to connect its another end part to a discharge oil port 32 set to a prescribed internal diameter for throttling a discharge oil amount passing through. In the halfway of this drain oil path 31, a switch valve 33 and a drain valve 40 are connected in series. In the switch valve 33, by moving a spool 36 against a spring 37 by a governor pressure PG input to port 38, a part between input/ output ports 34, 35 is closed. In the drain valve 40, oridinarily a ball-shaped valve of opening/closing the discharge oil port 32 is closed by a spring 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for an automatic transmission, and more particularly to a device for mitigating a shock when a manual valve is switched from an N position to a D position or an R position in a hydraulic automatic transmission. Is.

[0002]

2. Description of the Related Art Generally, in a hydraulic automatic transmission, a regulator valve for adjusting the discharge pressure of an oil pump to a predetermined line pressure and a P-R, N-N, D-position or the like are switched in conjunction with a shift lever. Manual valve for switching the line pressure supply oil passage, governor valve for adjusting line pressure to governor pressure according to vehicle speed, throttle valve for adjusting line pressure to throttle pressure according to throttle opening, and line pressure for friction element A plurality of shift valves, etc., for supplying the electric power are provided. The shift valve is switched according to the magnitude relationship between the governor pressure and the throttle pressure to switch the shift speed.

[0003]

By the way, the line pressure regulated by the regulator valve is set so as to increase in accordance with the throttle opening so as to have a characteristic similar to the engine torque characteristic as shown in FIG. ing. In particular, the line pressure when the throttle is fully closed (0%) is used to secure the clutch transmission torque corresponding to the engine brake torque, and when the throttle pedal is fully closed and when the accelerator pedal is slightly stepped, variations in throttle adjustment occur. Therefore, there is a circumstance in which the pressure cannot be reduced below a certain constant pressure P ₀ because it cannot be distinguished. As a result, when the manual valve is switched from the neutral position (P, N) to the traveling position (D, R, etc.), the clutch is strongly engaged due to the line pressure P ₀ ,
There is a problem that a shock occurs when switching.

In order to solve such a problem, for example, in Japanese Patent Laid-Open No. 366065/1992, in a hydraulic circuit for controlling engagement / disengagement of a reverse clutch and a reverse brake, an accumulator and a shift are provided in a hydraulic circuit of one friction element. By arranging with the valve, both friction elements are prevented from being fastened together quickly, and when the both friction elements are released, the oil discharge from the friction elements is delayed and the manual valve is moved between the N position and the R position. There is one that reduces the shock when switching. However, adding an accumulator to reduce shocks has the drawbacks of increasing the size of the hydraulic circuit and increasing the cost. Moreover, in the above hydraulic circuit, the manual valve is N
Shock cannot be prevented when switching from the D position to the D position.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic control device for an automatic transmission that reduces shock when the manual valve is switched from the neutral position to the traveling position.

[0006]

In order to achieve the above object, the present invention provides a regulator valve for adjusting the discharge pressure of an oil pump to a predetermined line pressure and P, R, N, D, etc. by manual operation. Switch to the position to switch the line pressure supply oil passage, a governor valve to adjust the line pressure to a governor pressure according to the vehicle speed, a throttle valve to adjust the line pressure to a throttle pressure according to the throttle opening, and a governor. In an automatic transmission provided with a plurality of shift valves that selectively supply a line pressure to a friction element to switch a gear position by a relative relationship between the pressure and the throttle pressure, the line pressure is supplied to the line pressure in the oil passage. Connect the drain oil passage to drain oil, and in the drain oil passage,
The drain oil passage is always closed and a drain valve that is opened only when the throttle opening is fully closed, and a switch valve that is always opened and that is closed when the governor pressure exceeds a predetermined value are provided in series.

[0007]

When the manual valve is switched from the neutral position to the traveling position, the line pressure is supplied from the manual valve to the starting friction element via the shift valve. At this time, if the throttle opening is fully closed, the drain valve is open, and if the vehicle is stopped, the switch valve is also open, so the line pressure is drained through the drain oil passage and the line pressure is Is reduced. As a result, a low line pressure is supplied to the friction element, and the shock at the time of switching is reduced. On the other hand, when the throttle opening is fully closed during running,
The drain valve is open, but the switch valve is closed, so line pressure is not drained from the drain oil passage. Therefore, the line pressure does not decrease, the friction element can hold a predetermined transmission torque, and the engine brake can be effectively operated.

When the drain valve and the switch valve are both opened, it is desirable to provide a throttle in the drain oil passage for limiting the amount of drained oil in order to control the drop margin of the line pressure.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a fourth forward speed / reverse direction 1 to which the present invention is applied.
1 shows a power transmission mechanism of an automatic transmission having a high speed gear stage.
This automatic transmission includes a torque converter 1 and an input shaft 2 to which engine power is transmitted via the torque converter 1.
, Three clutches C ₁ , C ₂ , C ₃ , two brakes b ₁ , B ₂ , a servo piston 3 for engaging and releasing the b ₁ brake, a Ravigneaux type planetary gear mechanism 4, and a one-way clutch. The OWC, the output gear 5, the output shaft 7, and the differential device 8 are provided.

Forward sun gear 4a of the planetary gear mechanism 4
And the input shaft 2 are connected via a C ₁ clutch,
The rear sun gear 4b and the input shaft 2 are connected via a C ₂ clutch, and the carrier 4c and the input shaft 2 are connected via a C ₃ clutch. The carrier 4c is connected to a fixed member 6 such as a casing through a B ₂ brake and a one-way clutch OWC that allows only the normal rotation (engine rotation direction) of the carrier 4c. The carrier 4c supports two types of planetary gears 4d and 4e, the forward sun gear 4a meshes with a long pinion 4d having a long shaft length, and the rear sun gear 4b meshes with a long pinion 4d via a short pinion 4e having a short shaft length. There is.
The ring gear 4f, which meshes only with the long pinion 4d, is coupled to the output gear 5. The output gear 5 is connected to the differential device 8 via the output shaft 7.

The power transmission mechanism includes clutches C ₁ ,
By operating C ₂ , C ₃ , brakes b ₁ , B ₂ and one-way clutch OWC, four forward gears and one reverse gear are realized as shown in Table 1. In the following table, ○ indicates the operating state. In addition, B ₁ is an operating side oil chamber of the servo piston 3, and B ₁ ′ is a releasing side oil chamber of the servo piston 3, and when hydraulic pressure is introduced into both oil chambers B ₁ and B ₁ ′ (3 The b ₁ brake is released at the time of speed.

[0012]

[Table 1]

As described above, only the C ₂ clutch is engaged in the first speed, the C ₂ clutch and the b ₁ brake are engaged in the _second speed, and all the clutches C _{1 to} C ₃ are engaged in the third speed. b _1, B ₂ brake is released, 4
At high speed, the C ₃ clutch and the b ₁ brake are engaged.
When the vehicle is moving backward (R range), the C ₁ clutch and the B ₂ brake are engaged.

The clutches C ₁ , C ₂ , C ₃ and the brakes b ₁ , B ₂ are operated by the hydraulic control device shown in FIG. The hydraulic control device is generally an oil pump 1.
0, regulator valve 11, manual valve 12,
Throttle valve 13, 1-2 shift valve 14, 2-3 shift valve 15, 3-4 shift valve 16, governor valve 17, throttle modulator valve 18, 4-2 timing valve 19, 2-4 timing valve 20, 3-2 The timing valve 21, 4-3 timing valve 22, servo control valve 23, b ₁ brake accumulator 24, C ₂ clutch accumulator 25, C ₁ clutch accumulator 26 and the like.

As is well known, the regulator valve 11 regulates the discharge pressure of the oil pump 10 to a predetermined line pressure P _L , and the manual valve 12 is manually operated to control the P, R, N, D, 3, 2. Switch to each position and switch the supply oil passage for the line pressure P _L. Further, the throttle valve 13 regulates the line pressure to a throttle pressure according to the throttle opening, and the governor valve 17 regulates the line pressure P _L to the governor pressure P _G according to the vehicle speed. The 1-2 shift valve 14, the 2-3 shift valve 15 and the 3-4 shift valve 16 are valves for ON / OFF controlling the hydraulic pressure to each friction element according to the vehicle speed and the throttle opening. Since the hydraulic control device is conventionally known, detailed description thereof will be omitted.

FIG. 4 is a hydraulic circuit diagram for line pressure control, which is a main part of the present invention. Supply oil line 3 for line pressure P _L
A drain oil passage 31 is connected in the middle of 0, and an end portion of the drain oil passage 31 communicates with an oil discharge port 32. In this embodiment (see FIG. 3), the drain oil passage 31 is connected to the oil passage 30 between the regulator valve 11 and the manual valve 12. However, the regulator valve 11 and the starting clutch C ₂ at the time of forward movement and the start clutch at the time of backward movement are connected. Any oil passage may be connected as long as it is in an oil passage connecting the clutches C ₁ and B ₂ .

A switch valve 33 and a drain valve 40 are connected in series in the middle of the drain oil passage 31. Switch valve 33 has an input port 34 of the line pressure P _L is input, and an output port 35 for outputting the line pressure P _L, a spool 36 for opening and closing these ports,
It has a spring 37 for urging the spool 36 in the direction in which the ports 34 and 35 communicate with each other, and a port 38 to which the governor pressure P _G is input so as to urge the spool 36 in the direction opposite to the spring 37. Governor pressure P _G when stopped
Is almost zero, the switch valve 33 opens the drain oil passage 31 by the spring 37. When the vehicle speed becomes equal to or higher than a predetermined vehicle speed (for example, 5 km / h), the switch valve 33 closes the drain oil passage 31 by the governor pressure P _G as shown by the chain double-dashed line.

The drain valve 40 has a ball-shaped valve body 41 that opens and closes the oil drain port 32 and a spring 42 that biases the valve body 41 in the valve closing direction. The inner diameter is set to a predetermined value in order to reduce the amount of oil drained. As shown in FIG. 5, the throttle cam 43 is provided outside the oil drain port 32.
When the throttle opening is fully closed, the projection 44a of the actuating member 44 (see FIG. 6) provided on the side of the throttle cam 43 opens the valve element 41 through the oil drain 32. It is possible. The operating member 44 is the drain port 32.
The fully closed position of the throttle cam 43 is defined by contacting the outer surface of the throttle cam 43. The operating member 44 is the drain port 32.
A communication groove 44b is formed in the operating member 44 from the outer peripheral portion to the protrusion 44a so as not to close the oil drain port 32 when it comes into contact with the outer surface of the operating member 44.

Next, the operation of the hydraulic control device having the above structure will be described. First, when the vehicle and the throttle opening in a stopped state is in the fully closed state, switching the manual valve 12 from the N position to the D position, the line pressure P _L is the manual valve 1
2. It is supplied to the C ₂ clutch via the shift valve 14. At the same time, the drain valve 40 moves the operating member 44.
Since the switch valve 33 is also opened (shown by the chain double-dashed line in FIG. 4), the line pressure P _L passes through the drain oil passage 31 and is discharged from the oil discharge port 32. Since the amount of oil discharged from the oil discharge port 32 is restricted, the line pressure P _L does not drop extremely, and is controlled to a predetermined oil pressure P ₁ as shown by the broken line in FIG. Thus, by lowering the line pressure P _L, the hydraulic pressure supplied to C ₂ clutch is also lowered, engagement shock of C ₂ clutch is relaxed. Further, when the manual valve 12 is switched from the P or N position to the R position, the line pressure becomes C ₁ clutch and B ₂
Although it is supplied to the brake, in this case also, since the drain valve 40 and the switch valve 33 are opened, a part of the line pressure P _L is discharged from the oil discharge port 32. Therefore, the engagement shock between the C ₁ clutch and the B ₂ brake is alleviated. On the other hand, when the throttle opening is fully closed during traveling, the drain valve 40 is opened, but the switch valve 33 is closed by the governor pressure P _G , so that the predetermined line pressure P ₀ is maintained. Therefore, each friction element can hold a predetermined transmission torque, and the engine brake can be effectively operated.

In the above embodiment, the actuating member 44 is integrally provided on the throttle cam 43, and the drain valve 40 is opened by this actuating member. However, the present invention is not limited to this. For example, the throttle valve 13 also serves as the drain valve. It is possible to That is, the throttle valve 1
Ports communicating with the drain oil passage may be formed in a part of 3, and these ports may be opened by the throttle valve 13 when the throttle is fully closed. In this case, since the throttle cam itself also serves as the operating member, the operating member can be omitted.

In the above-mentioned embodiment, the automatic transmission having the forward four-speed shift stage has been described. However, the present invention can be applied to a hydraulic automatic transmission having other shift stages. is there.

[0022]

As is apparent from the above description, according to the present invention, the line pressure is reduced only when the vehicle is stopped and the throttle opening is fully closed. Therefore, the manual valve is moved from the neutral position to the traveling position. When switched to, a low hydraulic pressure is introduced to the friction element for starting, and the switching shock can be alleviated. In addition, since the drain oil passage is closed by the switch valve even when the throttle opening is fully closed during traveling, the line pressure does not decrease and the clutch transmission torque corresponding to the engine braking torque can be secured.

[Brief description of drawings]

FIG. 1 is a diagram showing a line pressure characteristic of an automatic transmission.

FIG. 2 is a schematic mechanical diagram of a forward four-speed automatic transmission.

FIG. 3 is a hydraulic circuit diagram of the automatic transmission of FIG.

FIG. 4 is a circuit diagram of a main part of a hydraulic control device according to the present invention.

FIG. 5 is a diagram showing an operating mechanism of a drain valve.

FIG. 6 is a perspective view of a throttle cam.

[Explanation of symbols]

 10 Oil Pump 11 Regulator Valve 12 Manual Valve 13 Throttle Valve 14, 15, 16 Shift Valve 17 Governor Valve 33 Switch Valve 40 Drain Valve

Claims (1)

[Claims] 1. A regulator valve for adjusting the discharge pressure of an oil pump to a predetermined line pressure, and P,
A manual valve that switches to each position such as R, N, D to switch the line pressure supply oil passage, a governor valve that regulates the line pressure to a governor pressure that corresponds to the vehicle speed, and a throttle pressure that adjusts the line pressure to the throttle opening. In an automatic transmission equipped with a throttle valve which regulates pressure to a plurality of shift valves and a plurality of shift valves which selectively supply a line pressure to a friction element to switch a gear position by a relative relationship between the governor pressure and the throttle pressure, Connect a drain oil passage that drains the line pressure to the supply oil passage of, and always close the drain oil passage in the drain oil passage and the drain valve that opens only when the throttle opening is fully closed, and the drain oil passage. A hydraulic control device for an automatic transmission, which is provided with a switch valve that is always open and that is closed when the governor pressure exceeds a predetermined value.