JP2886178B2 - Hydraulic control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic control device for an automatic transmission, and more particularly to a hydraulic control device for an automatic transmission having three or more forward speeds.

[Conventional technology]

2. Description of the Related Art Conventionally, in the case of an automatic transmission having three or more forward speeds, power is transmitted via a one-way clutch in a first speed state, and a downshift from a third speed in a low throttle opening range passes through a second speed. In general, the gear is set so as to be shifted to the first speed. The reason is that, in the first speed state, power is transmitted via the one-way clutch, so that the engine brake is not effective and the emblem shock can be eliminated even if the gear is directly downshifted from the third speed to the first speed.

[Problems to be solved by the invention]

The problem with this type of automatic transmission is that the vehicle speed difference between the shift point at 32 shifts and the shift point at 23 shifts,
That is, the hysteresis between the third speed and the third speed cannot be made large.
That is, in order to directly downshift to the third speed and the first speed as described above, it is necessary to shift the shift point at the time of the 32nd shift in the low throttle opening range to the low vehicle speed side.
The shift point at the time of shifting also shifts to the low vehicle speed side, and a large hysteresis between the second and third speeds cannot be obtained, and there is a possibility that running may be unstable. The reason is that the governor pressure and the throttle pressure only act in opposing directions on the 2-3 shift valve that switches between the 2-3 speeds. Therefore, when the throttle opening is low (low throttle pressure), This is because the governor pressure (vehicle speed) required for upshifting is also low, and it is difficult to obtain large hysteresis.

Accordingly, it is an object of the present invention to provide a hydraulic control device for an automatic transmission that can increase hysteresis in a low throttle opening range and improve running stability.

[Means for solving the problem]

To achieve the above object, the present invention provides a governor valve that outputs a governor pressure that increases according to a vehicle speed and a throttle pressure that increases according to a throttle opening in an automatic transmission having three or more forward speeds. A throttle valve that outputs a kickdown pressure equivalent to the throttle pressure at a certain throttle opening or more, a regulator valve that regulates the discharge pressure of an oil pump to a predetermined line pressure, and supplies or discharges hydraulic pressure to a friction element, and Speed stage and n + 1 speed stage (n ≧
2) a shift valve that switches a port to a friction element, a spring that biases the spool in one direction, and a governor pressure that is input in a direction opposite to the spring load. Port and
A port where the throttle pressure is input in the same direction as the spring load, a port where the line pressure is input in the same direction as the spring load, and a port where the kickdown pressure is input in the same direction as the spring load are provided. The spool is n
In the speed state, the port to which the line pressure is input is opened to close the port to which the kick down pressure is input. In the n + 1 speed state, the port to which the line pressure is input is closed and the port to which the kick down pressure is input is opened. It is characterized by the following.

[Action]

That is, the throttle pressure is 0 when the throttle is fully closed, but the line pressure is also used as the oil pressure supplied to the friction element, so that the line pressure is maintained at a certain pressure or more even when the throttle is fully closed. Therefore, when the throttle pressure, the line pressure, and the spring load are applied to the shift valve in a direction opposite to the governor pressure at a low speed, compared to a throttle valve in which the throttle pressure and the spring load are opposed to the governor pressure. The shift point at the time of an upshift in the low throttle opening range can be shifted to the high vehicle speed side. That is, n speeds and n
A large hysteresis between the upshift and the downshift between the + 1st speed can be obtained, and the running stability can be improved.

Also, at the time of kick down, the throttle pressure, kick down pressure and spring load are applied in the direction opposite to the governor pressure at the high speed stage, so that the hysteresis can be reduced, and the kick down can be performed even at relatively high speeds. It can be suitably performed. Embodiment FIG. 1 shows a schematic configuration of an automatic transmission having three forward speeds and one reverse speed, which is an example of the present invention.

The power transmission mechanism of this automatic transmission includes an input shaft 2 driven by an engine via a torque converter 1, two clutches C ₁ and C ₂ , two brakes b ₁ and B ₂ , fastening brake b _1, a servo piston 3 to be released, a Ravigneaux type planetary gear mechanism 4, and the one-way clutch OWC,
And an output shaft 5.

The reverse sun gear 4a of the planetary gear mechanism 4 is a first clutch.
Through the C ₁ is coupled to the input shaft 2, a forward sun gear 4b is coupled to the input shaft 2 via the intermediate shaft 6 and the second clutch C _2. Carrier 4c is connected to the fixed member 7 such as a casing through a second brake B ₂ and the one-way clutch OWC. In addition, one-way clutch OW
C allows only the forward rotation (engine rotation direction) of the carrier 4c. The carrier 4c has two types of planetary gears 4.
d, 4e, the reverse sun gear 4a meshes with the first planetary gear 4d having a long shaft, and the forward sun gear
4b meshes with the first planetary gear 4d via the second planetary gear 4e having a short shaft length. 1st planetary gear 4d
The ring gear 4f that meshes with only the output shaft 5 is connected to the output shaft 5.

The power transmission mechanism includes clutches C ₁ and C ₂ , brakes b ₁ ,
By the operation of the B ₂ and the one-way clutch OWC, it realizes a gear position as in the following table. In the following table, ○ indicates the operating state.

In the above table, B ₁ is the engagement side hydraulic pressure of the servo piston 3,
B ₁ ′ indicates a release-side oil chamber of the servo piston 3. When hydraulic pressure is guided to both oil chambers B ₁ and B ₁ ′ (at the third speed), the release-side oil chamber B ₁ ′ is opened. because a large pressure receiving area, the first brake b ₁ is always released. Also, in the first gear of the D and 2 ranges, the engine brake does not operate due to the one-way clutch OWC, and the second brake is applied only in the first gear of the L range.
Since B ₂ is fastened, it is possible to operate the engine brake.

FIG. 2 shows a hydraulic circuit for operating the clutches C ₁ and C ₂ and the brakes b ₁ and B ₂ . In the figure, an oil pump 10, a regulator valve 11, a manual valve 1
2. Throttle valve 13, governor valve 14, 1-2 shift valve 15, 2-3 shift valve 16, 3-2 timing valve 17, relief valve 18, accumulator 19 for first clutch, accumulator 20 for second clutch, first It is composed of a brake accumulator 21 and the like.

In the above hydraulic circuit, the hydraulic pressure of each oil passage is as follows. That is, P _L is the line pressure, P _R is the retraction line pressure, P _T
Throttle pressure, P _K is a kick-down pressure, P _G is the governor pressure,
P _C1 is a first clutch pressure, P _C2 is a second clutch pressure, P _B1 is a first brake engagement pressure, P _B1 ′ is a first brake release pressure, and P _B2 is a second brake pressure.

Regulator valve 11 is a valve for pressure regulating the discharge pressure of the oil pump 10 to a desired line pressure P _L, the discharge pressure of the oil pump 10 is input to the center of the port 11a, a communication hole formed in the interior of the spool 11b The spool 11b moves to the left against the spring 11d by the oil pressure of the right end chamber 11c fed back via the valve, and when reaching the position shown in the figure, the drain port 11e is opened and the pressure oil is released from the oil pump 10c.
Is returned to the suction side. Therefore, the spool 11b is balanced at this position, and outputs the desired line pressure P _L to the output port 11.
Output from f. Plunger 11g is provided on the left portion of the regulator valve 11, plunger 11g by retracting hydraulic P _R led to the hydraulics and the back pressure chamber 11i is guided to the back pressure chamber 11h
Pushes the spool 11b to the right. Therefore, as shown in FIG. 3, the line pressure P _L at the time of forward movement maintains a constant oil pressure in proportion to the spring load of the spring 11d even when the throttle is fully closed, and increases up to the intermediate throttle opening in accordance with the throttle opening. When the throttle opening exceeds the intermediate throttle opening, the hydraulic pressure becomes substantially constant. Thus, the line pressure P _L for supplying a proper hydraulic pressure to each friction element, is set to be substantially approximate to the maximum engine torque at each throttle opening.

The manual valve 12 works in conjunction with the shift lever to
It has a spool 12a operated at each of N, D, 2, and L positions, and has a total of twelve ports 12b to 12m in which an oil path is switched by the spool 12a. Of these, the three ports 12b to 12d on the right are provided on the entire circumference,
e to 12m constitute individual ports which are independent in the upper and lower parts in the figure. And ports 12e and 12g, ports 12f and 12i, port
Each of 12j and 12m communicates with an external oil passage. port
12d the line pressure P _L from regulator valve 11 is input to, and is input throttle pressure P _T from the throttle valve 13 to be described later to the port 12l. And the spool 12a
Is shifted to each of the positions P, R, N, D, 2, and L, and the hydraulic pressure is output from each port as shown in the following table. In the table,
Crosses indicate drains.

As shown in FIG. 8, the throttle valve 13 includes a plunger 13a which is pushed leftward in conjunction with an accelerator pedal,
A spool 13c is pushed leftward by a plunger 13a via a spring 13b, and a spring 13d biases the spool 13c rightward. Line pressure P _{L at} port 13e
Is input, and the throttle pressure _PT is output from the port 13f. Since the throttle pressure _PT is fed back to the port 13g through the communication hole of the spool 13c, as shown in FIG. 4, the throttle pressure _PT increases almost linearly as the throttle opening increases. Becomes Note that the throttle pressure _PT is also guided from the port 13h to the port 13i, and only when the throttle opening is opened to a certain degree or more, such as during a kick down, the throttle pressure is transmitted from the port 13i to the port 13j via the port 13j. P _T and outputs a (this is referred to as kick-down pressure P _K). That is, the kick-down pressure P _K up to a certain degree as 5 (e.g. 85%) 0
, And the the throttle pressure P _T and Do圧becomes a more constant degree.

The governor valve 14 is attached to the output shaft 5 and has a line pressure P output from the port 12e of the manual valve 12.
_L is regulated to generate a governor pressure P _G (see FIG. 6) substantially proportional to the rotation speed of the output shaft 5, that is, the vehicle speed. In addition,
The configuration of the governor valve 14 is known, and a detailed description thereof will be omitted.

The 1-2 shift valve 15 is a valve for switching between the first and second speeds. In the figure, the upper half shows the first speed stage and the lower half shows the second speed stage. The valve 15 includes a first spool 15b urged rightward (first speed side) by a spring 15a, and a second spool 15c contacting a right end surface of the first spool 15b. Output first brake engagement pressure P _B1
And the second brake pressure P _B2 output from the port 15e. Governor pressure P _G is input to the right end port 15f, the port 15g is input always throttle pressure P _T,
Port 15h is connected to the port 12m of the manual valve 12, the port 15i kickdown pressure P _K via the three-way valve 30 to
(Excluding the L and R ranges) is input. Also port 1
5j and 15k are connected to port 12f of manual valve 12,
Ports 15l and 15m are connected to port 12k of manual valve 12, 15n is connected to port 12b of manual valve 12, and 15o is an orifice with port 12e of manual valve 12.
Connected via 31. Port 15p has orifice 32,
It is connected to a relief valve 18 and a back pressure chamber 11h of the regulator valve 11 described later via 33. in this way,
Relative to the first spool 15b and the second spool 15c, by the action of the governor pressure P _G from the right side, (the first speed) spring load and the throttle pressure P _T of the spring 15a from the left and kickdown pressure P _K
(At the second speed), the 1-2 speed is switched according to the magnitude relation of these loads.

The 2-3 shift valve 16 is a valve for switching the 2-3 speed, and has a spool 16b urged to the right (second speed side) by a spring 16a as shown in FIG. The first clutch pressure P _C1 (first
The brake release pressure P _B1 ′) is switched and controlled. The right port 16d is inputted governor pressure P _G, the port 16e is input line pressure P _L, the port 16f 1-2 shift valve 15
Port 15i via the kickdown pressure P _K (L, except for R-range) is input. The port 16g is connected to the port 12b of the manual valve 12, the port 16h is connected to the port 12c of the manual valve 12, and the port 16i receives the throttle pressure _PT . Since the time of the second speed (indicated by the upper half) is a drain port 16c, first clutch C ₁ is disengaged, the third speed when the hydraulic pressure P _C1 from the port 16c is (shown in the lower half) (P _B1 ' Will be output)
The first clutch C ₁ is engaged, the first brake b ₁ is released.

3-2 timing valve 17 is controlled 32 oil discharge characteristics of the first brake release pressure P _B1 'during transmission, in accordance with the first engagement characteristic of the brake b ₁ to the vehicle speed in other words. This valve comprises a spool 17b which is biased leftward by a spring 17a, the governor pressure P _G is inputted in a direction opposite to the spring 17a at the left port 17c. Also port
17d is connected to the release-side oil chamber B ₁ of the servo piston 3 'through the orifice 34, the port 17e is connected to the port 16c of the 2-3 shift valve 16 without passing through the orifice. At the time of 32 shifts at a low vehicle speed, since the spool 17b is at the position shown in the upper half, the pressure oil in the release side oil chamber B ₁ ′ is drained through the parallel orifices 34 and 35, and the engagement side oil chamber B ₁ first brake b ₁ in accordance with the hydraulic pressure rise of are fastened quickly. On the other hand, at the time of 32 shifts at high vehicle speed, the spool
Because 17b is in the position shown in the lower half, the pressure oil of the release-side oil chamber B ₁ 'is drained only through the orifice 35, the first brake b ₁ is gently fastened. Thus delaying the first engagement of the brake b ₁ at a high speed, by increasing the engine rotation, and relieve 32 during shifting of the shift shock.

The relief valve 18 is the back pressure chamber 11 of the regulator valve 11
h is a valve that adjusts the hydraulic pressure, and has a spool 18b urged leftward by a spring 18a. A left end port 18c is provided in the direction opposite to the spring 18a from the port 15p of the 1-2 shift valve 15. The throttle pressure _PT is derived. When the throttle pressure _PT input to the left end port 18c is equal to or less than the spring load of the spring 18a, the oil pressure in the back pressure chamber 11h is equal to the throttle pressure _PT, and when the throttle pressure _PT exceeds the spring load of the spring 18a. Since the relief valve 18 is drained, the oil pressure in the back pressure chamber 11h is limited to a constant oil pressure corresponding to the spring load of the spring 18a. Therefore, the line pressure P _L is a characteristic such as Figure 3.

Here, the 2-3 shift valve 16 which is a main part of the present invention is described.
The operation of will be described.

The first second-speed state, press the throttle pressure P _T and the port 16e is input to the spring load and the port 16i of the spring 16a, and the line pressure P _L is input to 16h is a spool 16b to the right, the governor pressure P _G is The spool 16b is pushed to the left to face this. On the other hand, the port 16e is closed in the third speed state, and since the line pressure P _L of the port 16h does not give a load to the spool 16b, and the kick-down pressure P _K to be input to the spring load and the throttle pressure P _T and the port 16f in press spool 16b to the right, acting as governor pressure P _G is facing the. Thus the line pressure P _L acts on the throttle pressure P _T in the same direction only at the second speed state, and since the line pressure P _L is holding a constant pressure in the throttle fully closed as in the third diagram, the throttle Downshift when fully closed (3rd gear 2
Large hysteresis H _IS as FIG. 7 between the fast) and upshift (second speed third speed) can provide. Therefore, in order to downshift directly to 3rd gear and 1st gear (the engine brake does not work at 1st gear in the D range),
As shown in FIG. 7, even when the shift point of the third speed and the second speed when the throttle is fully closed is set to be substantially the same as the shift point of the second speed and the first speed, the third speed, the second speed and the second speed and the third speed when the throttle is fully closed. large for hysteresis H _iS can be provided, running stability is improved between.

Incidentally, allowed to act kickdown pressure P _K to the throttle pressure P _T in the same direction during the third speed, it is to improve the kick-down performance in high vehicle speed range. The same is true for 1-2
The same can be said for the shift valve 15.

The present invention is applied not only to the 2-3 shift valve 16 of the automatic transmission having the third forward speed as in the above-described embodiment, but also to the 2-shift valve of the automatic transmission having the fourth forward speed or more. The present invention is similarly applicable to a three-shift valve or a shift valve that switches between higher speed stages.

〔The invention's effect〕

As apparent from the above description, according to the present invention, the line pressure is changed in the same direction as the throttle pressure and the spring load in the low speed stage, while the shift valve switches between the nth speed stage and the n + 1 speed stage (n ≧ 2). As a result, a large hysteresis between the upshift and the downshift in the low throttle opening range is obtained, and the running stability is improved.

Further, at the time of kick down from the high speed stage, the kick down pressure is guided in the same direction as the throttle pressure and the spring load, so that the kick down can be performed even at the time of high speed running, and good running performance can be obtained.

Furthermore, there is no need to provide a dedicated valve for generating hysteresis hydraulic pressure, and the valve can be shared by the regulator valve and the throttle valve, so that the hydraulic circuit can be simplified.

[Brief description of the drawings]

FIG. 1 is a power transmission mechanism diagram of an automatic transmission according to the present invention,
FIG. 2 is a hydraulic circuit diagram, FIG. 3 is a characteristic diagram of line pressure,
4 is a characteristic diagram of the throttle pressure, FIG. 5 is a characteristic diagram of the kick down pressure, FIG. 6 is a characteristic diagram of the governor pressure, FIG. 7 is a shift diagram, FIG. 8 is a structural diagram of the throttle valve, and FIG. 9 is 2
FIG. 3 is a structural diagram of a −3 shift valve. C ₁ , C ₂ … clutch, b ₁ , B ₂ … brake, OWC… one-way clutch, 3… servo piston, 4… planetary gear mechanism,
11… Regulator valve, 13… Throttle valve, 14…
Governor valve, 16 ... 2-3 shift valve, 18 ... relief valve.

Claims (1)

(57) [Claims] An automatic transmission having three or more forward speeds includes a governor valve that outputs a governor pressure that increases in accordance with a vehicle speed, and a governor valve that increases in accordance with a throttle opening and a throttle pressure that increases in accordance with a throttle opening. A throttle valve that outputs a kickdown pressure equivalent to the throttle pressure, a regulator valve that regulates the discharge pressure of the oil pump to a predetermined line pressure, and supplies or discharges a hydraulic pressure to a friction element, and the nth speed and n
A shift valve for switching between a first speed stage (n ≧ 2), a spool for switching a port to a friction element, a spring for urging the spool in one direction, and a governor pressure that is equal to a spring load. A port input in the opposite direction, a port input throttle pressure in the same direction as the spring load, a port input line pressure in the same direction as the spring load, and a kick down pressure input in the same direction as the spring load In the n-th speed state, the spool opens a port for inputting line pressure and closes a port for inputting kickdown pressure, and in the n + 1 speed state, a port for inputting line pressure. A hydraulic control device for an automatic transmission, characterized by closing a port and opening a port for inputting a kickdown pressure.