JPH08135779A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE: To provide an automatic transmission hydraulic control device capable of reducing torque occurring on an intermediate shaft during a shift from the n-1 gear to the n-gear and further capable of preventing a vehicle start due to the occurrence of racing immediately after a shift gear change from the drive range to the neutral range. CONSTITUTION: This automatic transmission has a clutch C2 with the number of speeds for 'n' shift gears (n: positive integer) and an engagement state between the first and the n-1 gears as well as a disengaged state at the n-gear. In addition, the transmission has a shift valve 16 selected between the n-1 gear and the n-gear for supplying and discharging pressure oil to and from the clutch C2 . Also, a one-way orifice 44 for allowing the supply of pressure oil to the clutch C2 and limiting the discharge thereof is connected to an oil passage connecting the valve 16 to the clutch C2 . In addition, a bypass oil passage 46 detouring the one-way orifice 44 is fitted with a timing valve 24 for closing the oil passage with a shift lever selected at the drive range, and keeping the passage communicated with the lever selected at the neutral range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for an automatic transmission, and more particularly to an n-th speed (n is a positive integer) speed change stage.
The present invention relates to a hydraulic control device for an automatic transmission that has an engagement element that is engaged during n-1 speed and that is released during n speed.

[0002]

2. Description of the Related Art Conventionally, as an automatic transmission having four forward speeds, for example, one disclosed in Japanese Patent Application Laid-Open No. 4-131566 is known. This automatic transmission includes a torque converter 1 and a torque converter 1 as shown in FIG.
Input shaft 2 through which engine power is transmitted, three clutches C ₁ , C ₂ , C ₃ and two brakes b ₁ , B
₂ and servo piston 3 for engaging and releasing the b ₁ brake
1, a Ravigneaux type planetary gear mechanism 4, a one-way clutch OWC, an output gear 5, an output shaft 7, and a differential device 8.

The 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 are connected. 2 is connected via a C ₃ clutch and an intermediate shaft 9. The carrier 4c is connected to a fixed member 6 such as a casing via a B ₂ brake and a one-way clutch OWC which 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 axial length,
The rear sun gear 4b meshes with the long pinion 4d via the short pinion 4e having a short axial length. Long pinion
The ring gear 4f, which meshes only with 4d, is connected 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 a clutch C ₁ ,
By operating C ₂ , C ₃ , brakes b ₁ , B ₂ and one-way clutch OWC, as shown in Table 1, four forward steps and one reverse step
It realizes the first gear. 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.

[0005]

[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. The brakes b ₁ and B ₂ are released and 4
At high speed, the C ₃ clutch and the b ₁ brake are engaged.

In the above automatic transmission, the C ₂ clutch is 1
It is continuously engaged from the third speed to the third speed and released at the fourth speed. In particular, third speed when shifting to the fourth speed, C ₁ is the clutch also is opened similarly to the C ₂ clutch, C ₁ release of the clutch is C ₂
If it is delayed from the release of the clutch, a large torque is applied to the intermediate shaft 9, so that the durability of the intermediate shaft 9 deteriorates. Therefore, it is desirable that the hydraulic pressure of the C ₂ clutch fall more gently than that of the C ₁ clutch.

[0008]

Therefore, as shown in FIG. 2, the one-way valve CV which allows only the supply of the hydraulic pressure to the C ₂ clutch is allowed in the oil passage connecting the 3-4 shift valve SV and the C ₂ clutch. It is conceivable to provide a one-way orifice consisting of the above and the orifice O. In this case, the line pressure P _L from the shift valve SV is guided to the C ₂ clutch via the one-way valve CV at the 1st to 3rd speeds, so that the C ₂ clutch pressure rises quickly. On the other hand, when switching from the third speed to the fourth speed, the shift valve SV is switched, so that the hydraulic pressure of the C ₂ clutch is drained through the orifice O. That is, since the C ₂ clutch pressure falls gently, it is possible to prevent a large torque from being generated in the intermediate shaft 9.

However, in the case of the above oil passage structure,
Even when shifting from the D range to the N range, the C ₂ clutch pressure gradually decreases only through the orifice O as in the case of switching from the 3rd speed to the 4th speed. Therefore, the racing state immediately after shifting to the N range. If so, the vehicle may move forward. Therefore, an object of the present invention is to change from n-1 speed to n
An object of the present invention is to provide a hydraulic control device for an automatic transmission, which can reduce the torque generated in the intermediate shaft when shifting to a high speed and can prevent the vehicle from moving forward due to racing immediately after shifting from the D range to the N range.

[0010]

In order to achieve the above object, the present invention has an n-th gear (n is a positive integer of 3 or more) and is engaged between the first gear and the (n-1) th gear. In an automatic transmission having an engagement element that is released at the n-th speed, a shift valve that switches between the n-1 speed and the n-speed and supplies and discharges hydraulic pressure to and from the engagement element; A one-way orifice that is provided in an oil passage connecting between the engagement element and the engagement element, allows oil to be supplied to the engagement element, and limits drainage of oil from the engagement element, the shift valve, and the engagement. A bypass oil passage provided so as to bypass the one-way orifice between the element and the element, and a timing valve provided in the bypass oil passage for closing the bypass oil passage during the D range and communicating with the N range. It is equipped with.

[0011]

When the N range is shifted to the D range, the hydraulic pressure is immediately introduced to the engaging element through the shift valve and the one-way orifice. Also, while driving in the D range, n-
When switching from the 1st speed to the nth speed, since the timing valve is closed, the hydraulic pressure of the engagement element gradually decreases via the one-way orifice and the shift valve. Therefore, the torque generated in the intermediate shaft can be reduced. Further, when the D range is shifted to the N range, the timing valve is switched to the N range side, and the C ₂ clutch and the shift valve are communicated with each other via the bypass passage. Therefore, C ₂
Clutch pressure is quickly drained through the timing valve and shift valve, and the C ₂ clutch is immediately released. Therefore, it is possible to prevent the vehicle from starting due to racing.

[0012]

FIG. 3 shows an example of a hydraulic control device according to the present invention. The hydraulic control apparatus is applied to an automatic transmission having a 1 in the same manner as the three clutches C _1, C _2, C ₃ and the two brakes b _1, B _2. Note that FIG. 3 differs from FIG. 1 in that the torque converter includes a lockup clutch LUC. The above hydraulic control device is roughly composed of an oil pump 10, a regulator valve 11, a manual valve 12, a throttle valve 13, a 1-2 shift valve 14, a 2-3 shift valve 15, a 3-4 shift valve 16, a governor valve 17, a throttle modulator. Valve 18, 4-2 Timing valve 19,
2-4 Timing valve 20, 3-2 Timing valve 21, 4-
3 Timing valve 22, 2-3 Timing valve 23, 3-4
Timing valve 24, servo control valve 25, lockup pressure control valve 26, lockup relay valve 27, lockup timing valve 2
8, lockup signal valve 29, b ₁ brake accumulator 30, C ₂ clutch accumulator 31, C
It consists of an accumulator 32 for _one clutch.
In the above hydraulic control device, the configuration other than the oil supply system for the C ₂ clutch is not directly related to the present invention, and therefore detailed description thereof is omitted here.

FIG. 4 is a circuit diagram of an oil passage system for the C ₂ clutch. In FIG. 4, the manual valve 12 selectively outputs the line pressure P _L from the output port 12b by manually operating the spool 12a at positions 2, 3, D, N, R and P. Regulator valve on input port 12c
The line pressure P _L is input from the 11. For example, when the spool 12a is operated to the D range position, the line pressure P _L is output from the output port 12b, and when the spool 12a is operated to the N range position, the output port 12b is drained.

[0014] 3-4 shift valve 16 is a valve for ON / OFF control of the C ₂ clutch pressure in accordance with the vehicle speed and throttle opening, to supply the line pressure P _L to the C ₂ clutch at the time of 1-speed to 3-speed Drain the C ₂ clutch at the 4th speed. This shift valve 16 includes a spool 16a and a plunger 16
b and are respectively urged to the right by springs 16c and 16d. The input port 16e is connected to the manual valve 12 via the oil passage 40. The oil passage 40 allows only oil drainage from the input port 16e to the manual valve 12 while the valve 41 and the orifice 42 are in parallel. It is provided in. Port 16f is a drain port, port
16g is an output port, and this output port 16g is an oil passage 43
It is connected to the C ₂ clutch via. This is in the oil passage 43, one-way orifice 44 limits the discharge oil from the allowable vital C ₂ clutch oil supply to C ₂ clutch is provided. The one-way orifice 44 is composed of a one-way valve 44a and an orifice 44b connected in parallel with each other. The left end port 16h of the shift valve 16 receives the throttle pressure P _T from the throttle valve 13 and the right end port 16i receives the governor pressure P _G from the governor valve 17.

3-4 Timing valve 24 is from D range to N
This timing valve is a valve for quickly draining the C ₂ clutch pressure when switching to the range.
24 is provided in a bypass oil passage 46 which is connected between the shift valve 16 and the C ₂ clutch and which bypasses the one-way orifice 44. Timing valve
24 is a spool biased to the left by a spring 24b
24a is provided, the line pressure P _L is introduced from the manual valve 12 to the signal port 24c on the left end side of the manual valve 12 during the D range, and the port 24d is connected to the C ₂ clutch. The port 24e is connected to the output port 16g of the shift valve 16 via the bypass oil passage 46. In addition, the signal port 24f containing the spring 24b has a governor valve 17
The governor pressure P _G is input from.

The operation of the hydraulic circuit shown in FIG. 4 will be described. At 1st to 3rd speed, spool of shift valve 16
16a is located on the right side, since the line pressure P _L is supplied via the shift valve 16 to the C ₂ clutch, C ₂ clutch is engaged. Further, since the spool 24a of the timing valve 24 is located on the right side, the port 24e and the port 24d are closed.

When shifting from the third speed to the fourth speed, the shift valve
The 16 spool 16a switches to the left, so the output port
16g communicates with drain port 16f. Therefore, C
The _second clutch oil pressure is gradually drained via only the orifice 44b, so the it is not released before the C ₁ clutch, can reduce the torque generated in the intermediate shaft 9.

On the other hand, when shifting from the 4th speed to the 3rd speed, the spool 16a of the shift valve 16 is switched to the right side, so that the input port 16e and the output port 16g communicate with each other. for that reason,
The line pressure P _L is immediately supplied to the C ₂ clutch via the one-way valve 44a, and the C ₂ clutch is quickly engaged.

When the D range is switched to the N range, the output port 12b of the manual valve 12 is drained. Since the spool 16a of the shift valve 16 is located on the right side, the hydraulic pressure of the C ₂ clutch tries to gently drain through the orifice 44b, the shift valve 16 and the manual valve 12. However, the timing valve 24
Since the hydraulic pressure of the port 24c is released, the spool 24a is switched to the left by the spring 24b, and the port 24e and the port 24d communicate with each other. Therefore, the hydraulic pressure of the C ₂ clutch is rapidly drained via the bypass oil passage 46, the shift valve 16 and the manual valve 12. Therefore, C
_{The two} clutches are released quickly, preventing the vehicle starting phenomenon during racing.

When the N range is switched to the D range, the line pressure P _L changes from the shift valve 16 to the one valve of the oil passage 43.
It is promptly supplied to the C ₂ clutch via 44a. Therefore, there is no delay in engagement of the C ₂ clutch.

In the above-mentioned embodiment, the automatic transmission having the forward four speeds is described, but the present invention can be applied to the automatic transmission having other speeds. Further, the engagement element of the present invention is not limited to the C ₂ clutch. Also,
The one-way orifice 44 is a one-way valve 44a as in the embodiment.
And the orifice 44b are not limited to being connected in parallel.

[0022]

As is apparent from the above description, according to the present invention, oil can be supplied to the engaging element in the oil passage connecting the shift valve and the engaging element, and the oil can be supplied from the engaging element. Since a one-way orifice that limits the oil drainage of
During the shift transition from the high speed to the n-th speed, the hydraulic pressure of the engagement element gradually decreases through the orifice, and the torque generated in the intermediate shaft can be reduced. Further, a bypass oil passage that bypasses the one-way orifice is provided between the shift valve and the engagement element, and a timing valve that closes the oil passage at the D range and communicates at the N range is provided in the bypass oil passage. , When shifting from the D range to the N range, the timing valve is switched to the N range side, and the C ₂ clutch and the shift valve are communicated with each other via the bypass passage.
Therefore, the C ₂ clutch pressure is quickly drained via the bypass oil passage, and the C ₂ clutch is immediately released.
Therefore, it is possible to prevent the vehicle from starting at the time of racing.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a general four-speed forward automatic transmission.

FIG. 2 is a circuit diagram of a supply oil passage system to a C ₂ clutch which is a premise of the present invention.

FIG. 3 is an overall circuit diagram of an example of a hydraulic control device for an automatic transmission according to the present invention.

FIG. 4 is a circuit diagram of a supply oil passage system to a C ₂ clutch in the hydraulic control device of FIG.

[Explanation of symbols]

C ₂ 1st clutch 16 3-4 Shift valve 24 3-4 Timing valve 43 Oil passage 44 One way orifice 44a One-way valve 44b Orifice 46 Bypass oil passage

Claims (1)

[Claims] 1. An automatic transmission having an n-th gear (n is a positive integer of 3 or more), an engagement element that is engaged between the 1st gear and the (n-1) th gear, and is released at the nth gear. A shift valve that switches between n-1 speed and n speed and supplies and discharges hydraulic pressure to and from the engagement element, and an oil passage that connects the shift valve and the engagement element. A one-way orifice for allowing oil supply to the engagement element and limiting oil discharge from the engagement element; and a one-way orifice provided between the shift valve and the engagement element so as to bypass the one-way orifice. And a timing valve which is provided in the bypass oil passage and is closed in the D range and communicates with the N range. .