JP2646864B2 - Hydraulic control device for automatic transmission - Google Patents

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.

[0002]

2. Description of the Related Art A conventional hydraulic control apparatus for an automatic transmission is disclosed, for example, in Japanese Patent Application Laid-Open No. 63-251652. The hydraulic control device for an automatic transmission shown therein has a low clutch, a high clutch, a 1-2 accumulator, a 2-3 accumulator, a back pressure adjusting valve, and a shift valve. The second speed is established when the low clutch is engaged and the high clutch is released, and the third speed is established when the low clutch is released and the high clutch is engaged. The shift valve supplies the oil pressure to the low clutch oil chamber and discharges the oil pressure of the high clutch oil chamber in the second speed state, and discharges the oil pressure of the low clutch oil chamber and supplies the oil pressure to the high clutch oil chamber To the third speed state. The 1-2 accumulator has a working pressure chamber formed on one surface side of the piston, and a back pressure chamber formed on the other surface side of the piston. The working pressure chamber communicates with the low clutch oil chamber. The 2-3 accumulator has a working pressure chamber formed on one surface side of the piston, and a back pressure chamber formed on the other surface side of the piston. The working pressure chamber communicates with the high clutch oil chamber. The back pressure adjusting valve can adjust a predetermined oil pressure by a solenoid according to the type of shift. The hydraulic pressure adjusted by the back pressure adjusting valve is supplied to the back pressure chambers of the 1-2 accumulator and the 2-3 accumulator. At the time of gear shifting, the back pressure adjusting valve adjusts a predetermined oil pressure and causes the adjusted oil pressure to act on the back pressure chambers of the 1-2 accumulator and the 2-3 accumulator. Thus, the hydraulic pressure at the time of shifting is adjusted to be appropriate.

[0003]

However, in the conventional hydraulic control apparatus for an automatic transmission as described above, the back pressure of two or more accumulators is adjusted by one back pressure adjusting valve. The following problems occur.
That is, when simultaneously switching the low clutch from the engaged state to the released state and simultaneously switching the high clutch from the released state to the engaged state, the back pressure regulating valve applies a relatively high back pressure to the high clutch so that the high clutch is engaged at an appropriate speed. -3 to the back pressure chamber of the accumulator. The same back pressure regulated by the back pressure regulating valve also acts on the back pressure chamber of the 1-2 accumulator. Therefore, the hydraulic pressure in the oil chamber of the low clutch is kept relatively high during the stroke of the piston of the 1-2 accumulator. As a result, the high clutch is engaged in a state where the torque capacity of the low clutch is relatively large, and the shift shock increases. An object of the present invention is to solve such a problem.

[0004]

The present invention solves the above-mentioned problems by draining the back pressure of an accumulator which communicates with the oil chamber of the frictional engagement element on the releasing side. Chi words, the present invention includes a first friction engagement element, the second frictional engagement element, first accumulator, second accumulator,
A back pressure adjusting valve and a shift valve, and when the first frictional engagement element is engaged and the second frictional engagement element is released, the speed becomes the mth speed, and the first frictional engagement element is released and When the two-friction engagement element is engaged, the gear shifts to the n-th speed, and the shift valve supplies the oil pressure to the oil chamber of the first friction engagement element and discharges the oil pressure of the oil chamber of the second friction engagement element. , Discharging the oil pressure of the oil chamber of the first frictional engagement element and supplying the oil pressure to the oil chamber of the second frictional engagement element
The first accumulator has a working pressure chamber formed on one surface side of the piston, and a back pressure chamber formed on the other surface side of the piston. The pressure chamber communicates with the oil chamber of the first frictional engagement element, and the second accumulator has a working pressure chamber formed on one side of the piston and a back pressure chamber formed on the other side of the piston. and which, working pressure chamber is in communication with the oil chamber of the second friction engagement element, the back pressure regulating valve in the hydraulic control device for an automatic transmission which is capable of adjusting a hydraulic pressure according to the type of gear shift, shift A back pressure switching valve is provided which can switch between an m-th speed position and an n-th speed in conjunction with the valve. The back pressure switching valve is provided in the back pressure chamber of the first accumulator at the m-th speed position. The hydraulic pressure regulated by the pressure regulating valve is supplied and the back pressure chamber of the second accumulator is drained. In the n-th speed position is configured to supply the hydraulic pressure adjusted by the back pressure regulating valve to the back pressure chamber of the second accumulator causes the draining back pressure chamber of the first accumulator. Further, the present invention has been described above.
In a hydraulic control device for an automatic transmission,
Back pressure switchable between m-th position and n-th speed
Valve is provided, and the back pressure switching valve is in the first position in the m-th speed position.
The accumulator is adjusted by the back pressure adjusting valve in the back pressure chamber
And the back pressure chamber of the second accumulator
Supply hydraulic pressure other than the hydraulic pressure regulated by the back pressure regulating valve
In the n-th speed position, the back pressure is applied to the back pressure chamber of the first accumulator.
When hydraulic pressure other than the hydraulic pressure regulated by the regulating valve is supplied
Both are set in the back pressure chamber of the second accumulator by the back pressure adjustment valve.
It is configured to supply the adjusted hydraulic pressure.

[0005]

When the shift from the m-th speed to the n-th speed is commanded, the shift valve is switched from the m-th speed position to the n-th speed position, and at the same time, the back pressure switching valve is also shifted from the m-th speed position to the n-th speed position. Switch to the high speed position. When the shift valve switches from the m-th speed position to the n-th speed position, the discharge of the oil pressure of the oil chamber of the first frictional engagement element is started, and the supply of the oil pressure to the oil chamber of the second frictional engagement element is started. Is done. When the back pressure switching valve switches from the m-th speed position to the n-th speed position, the hydraulic pressure in the back pressure chamber of the first accumulator is drained. Therefore, during the stroke of the piston of the first accumulator, the first friction engagement element The oil pressure in the oil chamber is maintained at a low oil pressure corresponding to the force of the spring of the first accumulator. On the other hand, the hydraulic pressure adjusted by the back pressure adjusting valve acts on the back pressure chamber of the second accumulator, and the oil pressure of the oil chamber of the second friction fastening element is maintained at a relatively high value during the stroke of the piston of the second accumulator. You. As described above, the oil pressure of the oil chamber of the first frictional engagement element is relatively low while the oil pressure of the oil chamber of the second frictional engagement element is relatively high during gear shifting, so that shift shock is reduced. When a relatively low predetermined oil pressure is applied to the back pressure chamber of the first accumulator, the oil pressure of the oil chamber of the first frictional engagement element is similarly kept low, and substantially the same operation can be obtained. it can.

[0006]

FIG. 1 shows an embodiment of the present invention. Shift valve 10
(This also serves as a back pressure switching valve as described later.) Has a spool 12 and a spring 14, and the spool 12 switches according to the hydraulic pressure acting on the port 16. The port 16 has a shift solenoid 1
The hydraulic pressure from 8 acts. At the position (m-th speed position) of the spool 12 shown in FIG. 1, the oil passage 20 and the oil passage 22 communicate with each other, and the oil passage 24 and the oil passage 26 communicate with each other. On the other hand, the oil passage 28 and the oil passage 30 are in a drain state. Spool 1
2 is switched from the state shown in FIG. 1 at the n-th speed position (n = m + 1 speed in this embodiment).
6 is drained, while oil passage 28 is connected to oil passage 20 and oil passage 30 is connected to oil passage 24. The oil passage 20 is an oil passage to which line pressure is supplied. The oil passage 24 is an oil passage to which the oil pressure from the back pressure adjusting valve 32 is supplied. The back pressure adjusting valve 32 has a solenoid whose duty ratio is controlled. The back pressure adjusting valve 32 can adjust a predetermined oil pressure during gear shifting according to a signal given from a control unit (not shown) and output the adjusted oil pressure to the oil passage 24. The oil passage 22 communicates with a first oil chamber 34 of the first frictional engagement element, and the oil passage 28 communicates with a second oil chamber 36 of the second frictional engagement element.

The oil passage 26 communicates with a back pressure chamber 40 of a first accumulator 38. The first accumulator 38 has a piston 42 and a spring 44. An operating pressure chamber 46 formed on the surface of the first accumulator 38 opposite to the back pressure chamber 40 is connected to the oil passage 22. The oil passage 30 communicates with the back pressure chamber 50 of the second accumulator 48.
The second accumulator 48 has a piston 52 and a spring 54. An operating pressure chamber 56 formed on a surface of the second accumulator 48 opposite to the back pressure chamber 50 with respect to the piston 52 communicates with the oil passage 28.

Next, the operation of this embodiment will be described. At the m-th speed, the shift solenoid 18 does not output the hydraulic pressure and the hydraulic pressure does not act on the port 16, so that the spool 12 of the shift valve 10 is at the position shown in FIG. Therefore, the oil passage 20 and the oil passage 22 communicate with each other, and hydraulic pressure is supplied to the first oil chamber 34. On the other hand, no oil pressure acts on the second oil chamber 36 because the oil passage 28 is drained. As a result, the m-th speed is realized. From this state the n-th
When a shift to a high speed is instructed, the shift solenoid 18 outputs a hydraulic pressure, which acts on the port 16, and the spool 12 of the shift valve 10 switches from the state shown in FIG.
As a result, the oil passage 22 is drained, and the line pressure of the oil passage 20 starts to be supplied to the oil passage 28. The oil passage 26 is drained, while the oil passage 30 is connected to the oil passage 2.
4 supplies the hydraulic pressure adjusted by the back pressure adjusting valve 32. Since the oil passage 26 is drained, no hydraulic pressure acts on the back pressure chamber 40 of the first accumulator 38 and the piston 42
1 moves upward in FIG. 1 only by the force of the spring 44 and discharges the oil in the working pressure chamber 46 to the oil passage 22.
Therefore, during the stroke of the piston 42, the first oil chamber 3
The oil pressure of No. 4 will be maintained at a relatively low oil pressure determined by the spring 44. FIG. 2 shows the change in the hydraulic pressure at this time. On the other hand, the back pressure chamber 5 of the second accumulator 48
The hydraulic pressure adjusted by the back pressure adjusting valve 32 acts on 0. Therefore, the hydraulic pressure in the working pressure chamber 56 is
4 so as to balance with the force of the hydraulic pressure acting on the back pressure chamber 50 in addition to the force of No. 4. Thus, during the stroke of the piston 52, the hydraulic pressure of the second oil chamber 36 is maintained at a relatively high state. FIG. 2 shows a change in the hydraulic pressure at this time. As a result, the oil pressure of the second oil chamber 36 is maintained at a relatively high state during the shift, while the oil pressure of the first oil chamber 34 is maintained at a relatively low state. As a result, the degree to which the first oil chamber 34 and the second oil chamber 36 are dragged while bearing torque is reduced, and shift shock is reduced. When the hydraulic pressure adjusted by the back pressure adjusting valve 32 is applied to the back pressure chamber 40 as in the related art, the hydraulic pressure of the first oil chamber 34 becomes high as shown by a broken line in FIG. Shift shock increases.

Incidentally, the spool 12 of the shift valve 10 is
A similar effect can be obtained when switching from the high speed position to the mth speed position. In this embodiment, the oil passage 26 and the oil passage 30
A valve function (back pressure switching valve) for switching the connection state of the oil passage 24 to the shift valve 10 is integrally formed with the shift valve 10.
That is, a dedicated back pressure switching valve may be provided, and the back pressure switching valve may be configured to switch in conjunction with the shift valve 10. Also, the drain port 60 of the shift valve 10
And 62 may be supplied with a relatively low oil pressure regulated by, for example, a constant pressure regulating valve. In this case, the relatively low oil pressure acts on the back pressure chamber 40 of the first accumulator 38, and the oil pressure of the first oil chamber 34 during shifting is higher than that of the above-described embodiment by a constant pressure. Basically, a similar effect can be obtained.

[0010]

As described above, according to the present invention, the back pressure chamber of the accumulator from which the hydraulic pressure is discharged during shifting is drained or a relatively low hydraulic pressure is applied. In addition, it is possible to reduce a shift shock by reducing the capacity of the friction engagement element during shifting.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a change in hydraulic pressure.

[Explanation of symbols]

 Reference Signs List 10 shift valve 32 back pressure adjusting valve 34 first oil chamber 36 second oil chamber 38 first accumulator 40 back pressure chamber 46 working pressure chamber 48 second accumulator 50 back pressure chamber 56 working pressure chamber

Claims (2)

(57) [Claims] A first friction fastening element, a second friction fastening element,
A first accumulator, a second accumulator, a back pressure adjusting valve, and a shift valve. When the first frictional engagement element is engaged and the second frictional engagement element is released, the speed becomes the m-th speed and the first friction When the engagement element is released and the second friction engagement element is engaged, the gear shifts to the n-th speed. The shift valve supplies the oil pressure to the oil chamber of the first friction engagement element and the oil pressure of the oil chamber of the second friction engagement element Can be switched between an mth speed position for discharging the oil pressure and an nth speed position for discharging the oil pressure of the oil chamber of the first frictional engagement element and supplying the oil pressure to the oil chamber of the second frictional engagement element, The first accumulator has a working pressure chamber formed on one surface side of the piston and a back pressure chamber formed on the other surface side of the piston, and the working pressure chamber is provided with an oil chamber of the first frictional engagement element. The second accumulator is a piston And a back pressure chamber formed on the other side of the piston, and the working pressure chamber communicates with the oil chamber of the second frictional fastening element. A pressure control valve is a hydraulic pressure control device for an automatic transmission that is capable of adjusting the oil pressure according to the type of speed change. In this hydraulic pressure control device, a back pressure switchable between an mth position and an nth speed in conjunction with a shift valve A valve is provided, and the back pressure switching valve supplies the hydraulic pressure adjusted by the back pressure adjusting valve to the back pressure chamber of the first accumulator and drains the back pressure chamber of the second accumulator at the m-th speed position, In the n-speed position, the first
Drain the back pressure chamber of the accumulator and
A hydraulic control device for an automatic transmission, characterized in that the hydraulic pressure adjusted by a back pressure adjusting valve is supplied to a back pressure chamber of an accumulator. 2. A first friction fastening element, a second friction fastening element,
A first accumulator, a second accumulator, a back pressure adjusting valve, and a shift valve. When the first frictional engagement element is engaged and the second frictional engagement element is released, the speed becomes the m-th speed and the first friction When the engagement element is released and the second friction engagement element is engaged, the gear shifts to the n-th speed. The shift valve supplies the oil pressure to the oil chamber of the first friction engagement element and the oil pressure of the oil chamber of the second friction engagement element Can be switched between an mth speed position for discharging the oil pressure and an nth speed position for discharging the oil pressure of the oil chamber of the first frictional engagement element and supplying the oil pressure to the oil chamber of the second frictional engagement element, The first accumulator has a working pressure chamber formed on one surface side of the piston and a back pressure chamber formed on the other surface side of the piston, and the working pressure chamber is provided with an oil chamber of the first frictional engagement element. The second accumulator is a piston And a back pressure chamber formed on the other side of the piston, and the working pressure chamber communicates with the oil chamber of the second frictional fastening element. A pressure control valve is a hydraulic pressure control device for an automatic transmission that is capable of adjusting the oil pressure according to the type of speed change. In this hydraulic pressure control device, a back pressure switchable between an mth position and an nth speed in conjunction with a shift valve The back pressure switching valve supplies the hydraulic pressure adjusted by the back pressure adjusting valve to the back pressure chamber of the first accumulator at the m-th speed position and supplies the back pressure adjusting valve to the back pressure chamber of the second accumulator. A hydraulic pressure other than the hydraulic pressure adjusted by the back pressure adjusting valve is supplied to the back pressure chamber of the first accumulator at the n-th speed position, and a hydraulic pressure other than the hydraulic pressure regulated by the back pressure adjusting valve is supplied to the back pressure chamber of the second accumulator. To the hydraulic pressure adjusted by the back pressure adjustment valve. Hydraulic control apparatus for an automatic transmission, characterized in that it is.