JPH09159018A - Hydraulic control device of automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the blow up of an engine at the speed changing time from a third speed to a fourth speed, while realizing the reduction of the speed change shock and an oil pump loss at the speed change time from a second speed to the third speed. SOLUTION: An automatic transmission has the speed change step of a forward four speeds and is composed so that C2 , C3 clutches can be tightened at a third speed time, the C3 clutch can be maintained in a tightening state at a fourth speed time and the C2 clutch can be released and the oil room of the C3 clutch is formed between the piston of the C2 clutch and the piston of the C3 clutch. By introducing the output pressure at a 2-3 shift valve 15 to the pressure reduction port of a regulator valve, the line pressures of the third/fourth speed is adjusted lower than that of the first/second speed. A timing valve 25 for outputting an oil pressure at the speed change transitional time from the third speed to the fourth speed is installed, the output pressure of the timing valve is introduced to the pressure increase port 11h of the regulator valve 11 and the line pressure is raised temporalily at the speed change transitional time from the third speed to the fourth speed.

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 controlling a line pressure during a transition from a third speed to a fourth speed in a mechanical automatic transmission.

[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.

[0003] The forward sun gear 4a of the planetary gear mechanism 4 and the input shaft 2 is connected via a C ₁ clutch, and the rear sun gear 4b and the input shaft 2 is connected via the C ₂ clutch, the carrier 4c and the input shaft 2 are connected via the C ₃ clutch and. The carrier 4c is B ₂ brake and the carrier
4c is connected to a fixed member 6 such as a casing via a one-way clutch OWC that allows only forward rotation (engine rotation direction). 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, and the rear sun gear 4b
Is engaged with the long pinion 4d via the short pinion 4e having a short shaft length. A ring gear 4f that meshes with only the long pinion 4d is connected to the output gear 5. The output gear 5 is connected to a differential 8 via an 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. Incidentally, B ₁ is working side oil chamber of the servo piston 3, B ₁ when the hydraulic pressure is introduced to 'indicates a release side oil chamber of the servo piston 3, both the oil chamber B _1, B _1' (3
The b ₁ brake is released at the time of speed.

[0005]

[Table 1]

As described above, in the first speed, only the C ₂ clutch is engaged, in the second speed, the C ₂ clutch and the b ₁ brake are engaged, and in the third speed, the C _{1 to} C ₃ clutches are engaged and the brake b is applied. ₁ , ₁ and B ₂ are released, and at the 4th speed, the C ₃ clutch and the b ₁ brake are engaged.

[0007]

In the above automatic transmission, as shown in FIG. 2 (A), a C ₂ clutch is provided with C on the inner diameter side.
₃ When placing the clutch oil chamber of the C ₃ clutch is formed between the piston and the C ₂ clutch piston of the C ₃ clutch. In this case, as shown in FIG.
When the piston returns missing oil pressure C ₂ clutch as (B), C ₃ since the volume expansion of the hatched portion δ to the oil chamber of the clutch takes place, supply hydraulic pressure to maintain the C ₃ clutch engagement state There is a need to. However, since such is provided an orifice for the supply oil passage C ₃ clutch to relax engagement shock, hydraulic pressure of the C ₃ clutch is lowered temporarily, as in FIG.

By the way, the line pressures of the third speed and the fourth speed are set to the first speed,
An automatic transmission has been proposed in which the line pressure is adjusted to be lower than the second speed line pressure. In this case, it is possible to reduce the shift shock from the 2nd speed to the 3rd speed, and to reduce the oil pump loss by lowering the line pressure at the 3rd speed and the 4th speed where the traveling time is long, thereby improving the fuel efficiency. it can. However, if the line pressure is lowered in the 3rd and 4th speeds, there is a possibility that the engine may be blown up due to the temporary decrease in the C ₃ clutch hydraulic pressure generated during the shift from the 3rd speed to the 4th speed as described above. (See Figure 3).

Therefore, an object of the present invention is to realize a reduction in shift shock and a reduction in oil pump loss when shifting from the second speed to the third speed, and at the same time, the engine blows up during the shift from the third speed to the fourth speed. An object of the present invention is to provide a hydraulic control device for an automatic transmission that can prevent the above.

[0010]

In order to achieve the above-mentioned object, the present invention has a forward four-speed gear and has a C ₂ speed at the 3rd speed.
It concluded the clutch and C ₃ clutch, while maintaining by a fastening state C ₃ clutch at the fourth speed, and configured to release the C ₂ clutch, and the piston of the C ₂ clutch C
_In an automatic transmission in which an oil chamber of a C3 clutch is formed between a piston of a _three clutch, a pressure reducing port is provided in a regulator valve for adjusting the discharge pressure of an oil pump to a predetermined line pressure, and a second speed and a third speed are provided. By switching the output pressure of the shift valve to the pressure reducing port of the regulator valve, the line pressure of the 3rd and 4th gears is adjusted to be lower than the line pressure of the 1st and 2nd gears and from the 3rd gear to the 4th gear. It is characterized in that a timing valve for outputting hydraulic pressure is provided at the time of a gear shift transition, and the regulator valve responds to the output pressure of the timing valve to temporarily increase the line pressure during a gear shift transition from the third speed to the fourth speed. .

An automatic transmission that operates as shown in Table 1 will be described as an example. When shifting from the 2nd speed to the 3rd speed, the C ₂ clutch maintains the engaged state, and the C ₁ clutch and the C ₃ clutch operate. It is engaged and the b ₁ brake is released. At this time,
The output pressure of the 2-3 shift valve is introduced to the decompression port of the regulator valve, and the line pressure is adjusted to a low level, which reduces shift shock and reduces the line pressure at high speed ratios of 3rd and 4th speed. Since it is low, oil pump loss is also small.

When shifting from the 3rd speed to the 4th speed, the hydraulic pressure of the C ₃ clutch is maintained, but the hydraulic pressures of the C ₁ clutch and the C ₂ clutch are released. When the piston returns missing oil pressure C ₂ clutch, occur more volume expanding the oil chamber of the C ₃ clutch, hydraulic pressure of the C ₃ clutch would drop transiently. Especially 3
Since the line pressures for the 4th and 4th speeds are adjusted to be lower than the line pressures for the 1st and 2nd speeds, a temporary decrease in the C ₃ clutch hydraulic pressure may cause the engine to blow up. However, timing valve outputs the hydraulic pressure during shifting transition from the third speed to the fourth speed, the regulator valve to temporarily increase the line pressure by this output pressure, it can be suppressed transient decline of C ₃ clutch hydraulic pressure, It is possible to prevent the engine from blowing up.

[0013]

FIG. 4 shows an example of a hydraulic control device according to the present invention. The hydraulic control apparatus is applied to, for example, an automatic transmission provided with a Figure 3 clutches C ₁ shown in 1, C _2, C ₃ and two brakes b _1, B _2. In addition,
The structure of the C ₂ clutch and the C ₃ clutch is the same as that of FIG.
₂ is arranged a piston of C ₃ clutch piston inner diameter side of the clutch, an oil chamber of the C ₃ clutch between the C ₃ clutch piston and C ₂ clutch piston is formed.

The above hydraulic control system includes an oil pump 10, a regulator valve 11, a manual valve 12, a 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, 2-3 Timing valve 19, 2-4 Timing valve 20, 3-2 Timing valve 21, 4-3 Timing valve 22, Servo control valve 23, 3- 4 Select timing valve 24, 3-4 Pressure timing valve 25,
An overdrive solenoid valve 26, a modifier valve 27, a secondary regulator valve 28, a B ₁ brake accumulator 29, a C ₂ clutch accumulator 30 and the like are provided.

In the above hydraulic control device, the configuration except the regulator valve 11, 2-3 shift valve 15, 3-4 shift valve 16 and 3-4 pressure timing valve 25 is not directly related to the present invention, and therefore a detailed description will be given. Omit it.

FIG. 5 shows a hydraulic circuit of a main part of the present invention.
The regulator valve 11 is a valve that regulates the discharge pressure of the oil pump 10 to a predetermined line pressure P _L , and includes a spool 11a, a plunger 11b, and a spring 11c that biases the spool 11a to the right. The discharge pressure of the oil pump 10 is input to the input / output port 11d and guided to the right end port 11e via the oil passage 31. 11f is the lubrication port and 11g
Is the drain port. The plunger 11b moves to the right by the hydraulic pressure input to the two pressure increasing ports 11h and 11i, and pushes the spool 11a to the right. Booster port 11h
The line pressure at the time of retreat or the output pressure of the 3-4 pressure timing valve 25, which will be described later, is selectively supplied from the manual valve 12 via the three-way valve 32. The throttle pressure is supplied to the pressure boosting port 11i. These pressure boosting ports 11h, 11i
The line pressure is adjusted to a higher hydraulic pressure than usual by the hydraulic pressure input to. In addition, the pressure reducing port is located between the right end port 11e of the regulator valve 11 and the drain port 11g.
11j is provided. This decompression port 11j has 2-3
From port 15b of shift valve 15 via oil passage 33
The hydraulic pressure that rises at high speed, that is, the hydraulic pressure of the C ₃ clutch is introduced. Therefore, the line pressure for the 3rd and 4th gears is
The pressure is adjusted to be lower than the line pressure for 2nd gear.

The 2-3 shift valve 15 is a valve for ON / OFF controlling the hydraulic pressure of the C ₃ clutch according to the vehicle speed and the throttle opening, the port 15a is input line pressure P _L, the port 15b is C _It is connected with ₃ clutches. In addition, governor pressure P _G is input to port 15c, and port 15c
Throttle pressure P _T is input to d and 15e, and throttle modulator pressure P _TM is input to port 15f. Port 15g is a drain port. 1 speed, since the time of 2-speed port 15b is drained to scavenge the oil pressure of the C ₃ clutch, third speed, and supplies the line pressure to the C ₃ clutch at the fourth speed.

3-4 The shift valve 16 is also a valve for controlling ON / OFF of the hydraulic pressure of the C ₂ clutch according to the vehicle speed and the throttle opening, and the line pressure is input to the port 16a,
Port 16b is connected to the C ₂ clutch. In addition, the governor pressure P _G is input to the ports 16c _and 16d, and the port 16c
The throttle pressure P _T is input to e. Line pressure is supplied from the port 16b to the C ₂ clutch in the 1st to 3rd speeds, and drained in the 4th speed. 3-4 The shift valve 16 is provided with a port 16f that drains at the 1st to 3rd speeds and outputs the line pressure at the 4th speed.
Is connected to the working-side oil chamber B ₁ of the servo piston 3 via an oil passage 37. Therefore, the hydraulic pressure can be rapidly supplied to the operating-side oil chamber B ₁ during the shift from the 3rd speed to the 4th speed, and the engagement of the b ₁ brake can be accelerated. The above oil passage 37 and one-way valve 38 is provided for allowing only the supply of hydraulic pressure to the hydraulic oil chamber B _1, 2-speed, the oil pressure of the working oil chamber B ₁ at the third speed port 16
It prevents it from being drained through f. Ports 16g and 16h are drain ports.

3-4 Pressure timing valve 25 is from 3rd to 4th
It is a valve that outputs hydraulic pressure during a transition to a speed change, and includes a spool 25b biased to the left by a spring 25a. The hydraulic pressure of the C ₂ clutch is guided to the left end port 25c via the oil passage 34 as a signal pressure, and the output port 25d is connected to the three-way valve 32 via the oil passage 35. Input port 25e is a port of 3-4 shift valve 16 via oil passage 36
It is connected to 16f. The port 25f is a drain port.

The operation of the hydraulic circuit shown in FIG. 5 will be described. In the 1st and 2nd speeds, the hydraulic pressure of the C ₃ clutch is drained through the 2-3 shift valve 15, and the C ₂ clutch is
Since the hydraulic pressure is supplied from the 3-4 shift valve 16, the C ₂ clutch is engaged and the C ₁ clutch is released.

At the time of shifting from the 2nd speed to the 3rd speed, the 2-3 shift valve 15 is switched to the left side, and the hydraulic pressure is supplied to the C ₃ clutch, and at the same time, the regulator valve is supplied via the oil passage 33.
The hydraulic pressure is also supplied to the pressure reducing port 11j of 11. for that reason,
It is possible to regulate the line pressures of the third and fourth speeds lower than the line pressures of the first and second speeds.

When shifting from the third speed to the fourth speed, the 3-4 shift valve 16 is switched to the left side, and the C ₂ clutch pressure P _C2 is drained. That is, the C ₃ clutch maintains the engaged state and the C ₂ clutch is released. 3 When gear piston missing oil pressure C ₂ clutch during shifting to the fourth speed returns, occurs more volume expanding the oil chamber of the C ₃ clutch as shown in FIG. 2 (B), the oil pressure of the C ₃ clutch transient Will be depressed. In particular, since the line pressure is adjusted low at the 3rd and 4th speeds, a temporary drop in the C ₃ clutch hydraulic pressure may cause the engine to blow up.

However, before shifting from the 3rd speed to the 4th speed, the 3-4 pressure timing valve 25 is at the right position as shown in FIG. 5, and connects the input port 25e and the output port 25d. Therefore, at the moment when the 3-4 shift valve 16 is switched to the left side, the 3-4 pressure timing valve 25 outputs hydraulic pressure to the pressure increasing port 11h of the regulator valve 11 via the oil passage 35. Therefore, the line pressure P _L increases before the C ₂ clutch hydraulic pressure decreases, and the hydraulic pressures of the C ₂ clutch and the C ₃ clutch both temporarily increase as shown in FIG. 6. Therefore, even if the C ₃ clutch hydraulic pressure drops transiently, the amount of the drop can be made small and the engine can be prevented from rising.

When the C ₂ clutch hydraulic pressure falls below the spring load Sp, the 3-4 pressure timing valve 25 is switched to the left side by the spring 25a, and the hydraulic pressure of the pressure increasing port 11h of the regulator valve 11 is drained. Therefore, the line pressure P _L is adjusted to the original low hydraulic pressure at the 3rd and 4th speeds. In FIG. 6, t ₁ is a 3-4 shift valve 16
There indicates the time when switched to the left, t ₂ denotes the time 3-4 pressure timing valve 25 is switched to the left.

FIG. 7 shows a second embodiment of the present invention. In the first embodiment, the output pressure of the 3-4 pressure timing valve 25 is led to the pressure increasing port 11h of the regulator valve 11, but in this embodiment, the 2-3 shift valve 15 and the pressure reducing port 11j of the regulator valve 11 are connected. By providing the cut valve 40 for opening and closing the oil passage 33, the line pressure P _L is increased during the transition from the third speed to the fourth speed. 7, the same parts as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted.

The cut valve 40 has a spool 40b biased to the right by a spring 40a, and the output pressure of the 3-4 pressure timing valve 25 is introduced as a signal pressure to the right end port 40c. The input port 40d is connected to the C ₃ clutch and the output port 40e is connected to the pressure reducing port 11j. The port 40f is a drain port.

The first to third speeds are the same as in the first embodiment. In the third speed, the C ₃ clutch hydraulic pressure is guided to the pressure reducing port 11j of the regulator valve 11 via the cut valve 40, so that the line pressure P _L is regulated to a low hydraulic pressure. When the output pressure of the 3-4 pressure timing valve 25 is input to the right end port 40c of the cut valve 40 during the transition from 3rd speed to 4th speed, the spool 40b switches to the left side and the pressure reducing port 11j
Drain the hydraulic pressure of. Therefore, the line pressure P _L is 1
Higher hydraulic pressure equivalent to 2nd speed. As a result, similarly to FIG. 6, the hydraulic pressures of the C ₂ clutch and the C ₃ clutch both temporarily rise, and even if the hydraulic pressure of the C ₃ clutch drops transiently, the amount of the drop can be made small and the engine blows up. It can be prevented. When the shift to the 4th speed is completed, the output pressure of the 3-4 pressure timing valve 25 is drained, so the cut valve 40 is switched to the right side again, and C ₃
The clutch hydraulic pressure is guided to the pressure reducing port 11j to adjust the line pressure P _L to a low hydraulic pressure.

The hydraulic circuits of the above-described two embodiments are merely examples of the present invention. In response to the output pressure of the timing valve, the regulator valve temporarily holds the line pressure during the transition from the third speed to the fourth speed. If you want to raise
Any circuit can be used.

[0029]

As is apparent from the above description, according to the present invention, the output pressure of the 2-3 shift valve for switching between the 2nd speed and the 3rd speed is led to the pressure reducing port of the regulator valve. The line pressure of the 4th speed can be adjusted to be lower than the line pressure of the 1st speed and the 2nd speed, the shift shock from the 2nd speed to the 3rd speed can be reduced, and the oil pump loss at the time of traveling the 3rd speed and the 4th speed can be reduced. In addition, the regulator valve is adapted to temporarily increase the line pressure during the transition from the third speed to the fourth speed in response to the output pressure of the timing valve that outputs the hydraulic pressure during the transition from the third speed to the fourth speed. It is possible to suppress a transient drop in the hydraulic pressure of the C ₃ clutch at the time of shifting from the 3rd speed to the 4th speed and prevent the engine from rising. Further, in the past, due to the transient drop in the C ₃ clutch hydraulic pressure, the specifications of other elements (orifices, etc.) that influence the shifting performance were restricted, but in the present invention, shifting from the 3rd speed to the 4th speed is performed. Since the line pressure is increased only during the transition, there is an effect that the optimum value as the gear shifting performance can be freely set without restricting the specifications of other elements that influence the gear shifting performance.

[Brief description of the drawings]

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

FIG. 2 is an operation diagram of the C ₂ and C ₃ clutches when shifting from the third speed to the fourth speed.

FIG. 3 is a hydraulic pressure change diagram of C ₂ and C ₃ clutches when shifting from the third speed to the fourth speed.

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

FIG. 5 is a circuit diagram of a main part of a hydraulic control device according to the present invention.

FIG. 6 is a hydraulic pressure change diagram of the C ₂ and C ₃ clutches when shifting from the third speed to the fourth speed according to the present invention.

FIG. 7 is a circuit diagram of a second embodiment of the hydraulic control device according to the present invention.

[Explanation of symbols]

C ₂ C ₂ clutch C ₃ C ₃ clutch 10 Oil pump 11 Regulator valve 11h Pressure increasing port 11j Pressure reducing port 15 2-3 Shift valve 16 3-4 Shift valve 25 3-4 Pressure timing valve 40 Cut valve

Claims (3)

[Claims] It has 1. A fourth forward speed gear stage, concluded and the C ₃ clutch 1 C ₂ clutch at the time of 3-speed, while maintaining the C ₃ clutch engagement state during the fourth speed, releasing the C ₂ clutch And the piston of the C ₂ clutch and the C ₃
In the automatic transmission which is formed an oil chamber of the C ₃ clutch between the piston of the clutch, the regulator valve pressure regulating the discharge pressure of the oil pump to a predetermined line pressure provided vacuum ports, switching between the second speed and the third speed 2-3 By guiding the output pressure of the shift valve to the pressure reducing port of the regulator valve,
In addition to adjusting the line pressures of the 1st and 2nd speeds lower than the line pressures of the 1st and 2nd speeds, a timing valve that outputs hydraulic pressure during a transition from the 3rd speed to the 4th speed is provided, and responds to the output pressure of the timing valve. The regulator valve is a hydraulic control device for an automatic transmission characterized by temporarily increasing the line pressure during a transition from the third speed to the fourth speed. 2. The hydraulic control device for an automatic transmission according to claim 1, wherein the regulator valve is provided with a pressure increasing port, and the output pressure of the timing valve is led to the pressure increasing port of the regulator valve. Hydraulic control device for automatic transmission. 3. The hydraulic control device for an automatic transmission according to claim 1, further comprising a cut valve for opening and closing an oil passage connecting the 2-3 shift valve and the pressure reducing port of the regulator valve, and the output of the timing valve. A hydraulic control device for an automatic transmission, wherein the pressure is used as a signal pressure for operating a cut valve in a closing direction.