JPH02286962A - Hydraulic controller of automatic transmission - Google Patents

Abstract

PURPOSE:To improve travelling stability by introducing governer pressure and throttle pressure in mutually opposite directions relative to a shift valve, and line pressure and the throttle pressure in the same direction only on a Neutral speed stage. CONSTITUTION:In a 2 speed state, 2-3 shift valve 16 pushes a spool 16b right wards by the urging pressure of spring 16a, throttle pressure from a throttle valve 13 to a port 16i and line pressure to ports 16e, 16h, and govener pressure from a govener valve 14 pushes if leftwards opposingly. Meantime, in a 3 speed state, since the port 16e is closed, and the line pressure of the port 16h is not applied to the spool 16b, the spool 16b is pushed rightwards by the urging pres sure of the spring 16a, the throttle pressure and kick-down pressure to a port 16t, and is pushed by the governer pressure opposingly. Consequently, only in the 2 speed state, the line pressure is applied in the same direction as that of the throttle pressure, and even if a throttle valve is fully closed, the line pressure maintains constant oil pressure to give hysteresis between 3-2 and 2-3 so that travelling stability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic control device for an automatic transmission, and particularly to a hydraulic control device for an automatic transmission having three or more forward speeds.

[Conventional technology]

Conventionally, in the case of an automatic transmission having three forward speeds or more, power is transmitted via a one-way clutch in the first gear state, and a downshift from the third gear in a low throttle opening range is transmitted through the second gear. Generally, the gear is set so that the gear is shifted to the first speed without stopping. The reason for this is that in the L speed state, power is transmitted via a one-way clutch, so the engine brake is not effective, and engine lock can be eliminated by directly downshifting from 3rd gear to L speed.

[Problem to be solved by the invention]

By the way, the problem with this type of automatic transmission is the difference in vehicle speed between the shift point during 3-way 2-shift and the shift point during 2-03 shift.
-The hysteresis between 3rd gear cannot be maintained to a large extent.

In other words, in order to directly downshift from 3rd gear to 1st gear as described above, it is necessary to shift the shift point from 3rd to 2nd gear in the low throttle opening range to the lower vehicle speed side, but for this purpose, 2= 4
The shift point during the third gear shift also shifts to the low vehicle speed side, and there is a risk that the hysteresis between the second and third gears will not be large, resulting in unstable driving. The reason for this is that the governor pressure and throttle pressure act in opposite directions on the 2-3 shift valve that switches between 2-3 speeds, so the throttle opening at low throttle openings (
This is because when the throttle pressure is low, the governor pressure (vehicle speed) necessary for upshifting is also low, making it difficult to obtain large hysteresis.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic control system for an automatic transmission that can increase hysteresis in a low throttle opening range and improve running stability.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a governor pulp that outputs governor pressure that increases according to vehicle speed, a throttle valve that outputs throttle pressure that increases according to throttle opening, and a line pressure that always maintains a constant pressure or higher. It is equipped with a regierator valve that outputs an output, and a shift pulp that supplies or outputs hydraulic pressure to a friction element and switches between n speed and n+1 speed (n≧2), and controls governor pressure and throttle to the shift valve. The line pressure is guided in the opposite direction to the throttle pressure, and the line pressure is guided in the same direction as the throttle pressure only in the n-speed gear.

[Effect]

111, the throttle pressure is O when the throttle is fully open, but since the line pressure is also used as the oil pressure supplied to the friction elements, it is maintained above a certain pressure even when the throttle is fully closed. Therefore, if the throttle pressure and line pressure are directed to the shift valve in a direction that opposes the governor pressure in low gears, the increase in throttle opening in the low throttle opening range will be greater than when only the throttle pressure is directed opposite the governor pressure. The shift point during shifting can be shifted to the higher vehicle speed side.

In other words, the hysteresis between upshift and downshift between the n speed and the n+l speed can be increased, and driving stability can be improved.

〔Example〕

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, C, two brakes b+, Bz, and a first brake b1. concluded.

It is composed of a releasing servo piston 3, a Ravignaux-type planetary gear mechanism 4, a one-way clutch OHC, and an output shaft 5.

A reverse sun gear 4a of the planetary gear mechanism 4 is connected to the input shaft 2 via a first clutch CI, and a forward sun gear 4b is connected to the input shaft 2 via an intermediate shaft 6 and a second clutch Cz. The carrier 4c is connected to a fixed member 7 such as a casing via a second brake B2 and a one-way clutch C. Note that the one-way clutch OWC only allows forward rotation of the carrier 4c (engine rotation direction). The carrier 4c supports two types of planetary gears 4d and 4e, the reverse sun gear 4a meshes with the first planetary gear 4d having a long shaft length, and the forward sun gear 4b meshes with the first planetary gear 4e through a second planetary gear 4e having a short shaft length. It meshes with 4d. A ring gear 4f meshing with the first planetary gear 4d is connected to the output shaft 5.

The power transmission mechanism includes clutches C, C, and brake b.
+, Bz, and one-way clutch leaf C in the zero-order table that realizes the gear stage as shown in the following formula, O indicates the operating state.

In the above table, B indicates the oil chamber on the engagement side of the servo piston 3, and BIo indicates the oil chamber on the disengagement side of the servo piston 3. When hydraulic pressure is led to both oil chambers B, B, ' (3rd gear (time), the pressure-receiving area of the release-side oil chamber B,1 is large, so the first brake b is always released. Also, D,
In the L gear of the 2nd range, the one-way clutch OW
Engine brake does not work because of C, and 1 in L range.
Since the second brake B8 is engaged only in gear, the engine brake can be operated.

Figure 2 shows the above clutches C, C, and brakes b+, B.
The hydraulic circuit for operating z is shown.

In the figure, an oil pump 10, a regulator valve 1
1, Manual pulp 12, Throttle valve 13, Governor valve 14.1-2 Shift valve 15.2-3 Shift pulp 16.3-2 Timing valve 17, Relief pulp I8, Achiemulator 19 for the first clutch, Second
Akie emulator for clutch 20. It is composed of a first brake accumulator 21 and the like.

In the above hydraulic circuit, the oil pressure of each oil passage is as follows. That is, PL is the line pressure, Pヮ is the line pressure when reversing,
Py is throttle pressure, Pe is kickdown pressure, Pc is governor pressure, PC+ is first clutch pressure, Pcz is second clutch pressure, P□ is first brake engagement pressure, P□・ is first
Brake release pressure, PI! is the second brake pressure.

The regulator valve 11 is a pulp for regulating the discharge pressure of the oil pump 10 to a desired line pressure PL, and the discharge pressure of the oil pump 10 is input to the central boat 11a, and is connected to a communication hole formed inside the spool llb. The spool llb moves to the left against the spring lid by the hydraulic pressure of the right end chamber 11c fed back through the spool llb, and when it reaches the position shown in the figure, the drain boat lle opens and the pressure oil flows to the suction side of the oil pump lO. be returned to. Therefore, the spool flb is balanced at this position and outputs the desired line pressure PL! - Output from IH. A plunger 1.1g is provided on the left side of the regulator valve 11, and the hydraulic pressure guided to the back pressure chamber 11h and the back pressure chamber 111 are connected to each other.
The plunger l1g pushes the spool llb to the right by the retreat hydraulic pressure P1 guided by. Therefore, as shown in Fig. 3, the line pressure PL during forward movement maintains a constant oil pressure balanced with the spring load of the spring lid even when the throttle is fully closed, and increases according to the throttle opening up to an intermediate throttle opening. When the intermediate throttle opening is exceeded, the oil pressure becomes almost constant. In this way, the line pressure PL is set to approximately correspond to the maximum engine torque at each throttle opening in order to supply appropriate oil pressure to each friction element.

The manual valve 12 is connected to the shift lever lever P,
R, N, D, 2. Spool 12 operated to each position of L
a, and has a total of 12 ports 2b to 12 surfaces whose oil paths are switched by this spool 12a. Among these, the three boats 12b to 12d on the right side are provided all around the boat, and the other boats 120 to 12- constitute independent and separate boats vertically in the figure. And Bo)
12e and 12g, boats 12f and 12+, boat 1
2. 1 and 12m are connected through external oil passages. Line pressure PL is input to the boat 12d from the regulator valve 11, and throttle pressure P.7 is input to the boat 121 from a throttle valve 13, which will be described later. Then, the spool 12a is set to P, R, N, D, 2. L(
7) By shifting to each position, oil pressure is output from each boat as shown in the following equation. In addition, in the table, the X mark indicates a drain.

The throttle valve 13 includes a plunger 13a that is pushed to the left in conjunction with the accelerator pedal, a spool 13c that is pushed to the left by the plunger 13a via a spring 13b, and a spring 13d that urges the spool 13c to the right. Equipped with: Boat 13e has line pressure P
L is manually powered, and the throttle pressure P from 13f (bow)
, is output. Since the throttle pressure P is fed back to the boat 13g through the communication hole of the spool 13c, the throttle pressure P increases almost linearly as the throttle opening increases, as shown in FIG. becomes. In addition, the throttle pressure Pa is 3h
The throttle pressure PT is also guided from the boat 13i to the boat 13i (kickdown pressure P) only when the throttle opening is opened to a certain opening or more, such as during kickdown.

) is output. In other words, kickdown pressure P,
As shown in FIG. 5, is 0 up to a certain opening degree (for example, 85%), and becomes the same pressure as the throttle pressure PT when the opening degree exceeds the certain opening degree.

The governor valve 14 is attached to the output shaft 5, and regulates the line pressure Pt output from the boat 12e of the manual valve 12 to create a governor pressure P6 approximately proportional to the rotational speed of the output shaft 5, that is, the vehicle speed (see Fig. 6). ) is occurring. The configuration of the governor valve 14 is well known, and detailed explanation thereof will be omitted.The 1-2 shift valve 15 is
- This is a valve for switching between 2nd speed, and the upper half of the figure shows 1st speed and the lower half shows 2nd speed. This valve 15
The boat 1 includes a first spool 15b urged to the right (to the far side) by a spring 15a, and a second spool 15c in contact with the right end surface of the first spool 15b.
Switching control is performed between the first brake engagement pressure P□ outputted from the boat 15d and the second brake pressure PI2 outputted from the boat 15e. Governor pressure P6 is input to the right end boat 15f, throttle pressure P is always input to the boat 15g, and boat 15h is connected to the boat 12 of the manual valve 12.
11, and kickdown pressure PK (excluding L and R ranges) is input to the boat 151 via a three-way valve 30. Also, Beau N5j.

15 is connected to the boat 12f of the manual valve 12, the boat 15L15- is connected to the boat 12 of the manual valve 12, and 15n is connected to the manual valve 12.
150 is connected to the boat 12e of the manual valve 12 via the orifice 31. The boat 15p connects a relief valve 18 and a regulator valve 11 to be described later through orifices 32 and 33.
The back pressure chamber 11h is connected to the back pressure chamber 11h. In this way, the first
Governor pressure P is applied from the right to the spool 15b and the second spool 15c, and the spring 15 is applied from the left.
By applying the spring load a, the throttle pressure Pv (at 1 speed), and the kickdown pressure Pg (at 2nd speed), the 12th speed is switched depending on the magnitude relationship of these loads.

2-3 The shift valve 16 is a valve for switching between 2nd and 3rd speeds, and is moved to the right (2nd speed side) by the spring 16a.
It has a spool 16b biased towards the boat 16.
The first clutch pressure P output from c.

(first brake release pressure Pal) is switched and controlled.

Governor pressure PG is input to the right end boat 16d, line pressure PL is input to the boat 16e, and kickdown pressure PX (L, R range) is input to the boat 16f via the boat 51 of the 1-2 shift pulp 15. Exclusion () is input.

Also, boat 16g is boat 1 with manual valve 12.
2b, and boat 16h is connected to manual valve 12.
The boat 16i is connected to the boat 12c, and a throttle pressure P is input to the boat 16i. In 2nd gear (shown in the upper half), boat 16c is drained, so the first
Crunch C3 is released, and in 3rd gear (shown in the lower half), oil pressure P,, (same as P is released.

The 3-2 timing pulp 17 controls the oil drainage characteristics of the first brake release pressure P□· during 3->2 gear shifting, in other words, the engagement characteristics of the first brake b, in accordance with the vehicle speed. This valve includes a spool 17b urged leftward by a spring 17a, and a governor pressure P is input to the left end bore 7c in a direction opposite to the spring 17a. Further, the boat 17d is connected to the release side oil chamber B1° of the servo piston 3 via the orifice 34, and the boat 17d is connected to the release side oil chamber B1° of the servo piston 3.
7e is connected to the boat 16c of the 2-3 shift valve 16 without an orifice. During 3-way 2-speed shifting at low vehicle speeds, the spool 17b is in the position shown in the upper half, so the pressure oil in the release side oil chamber B1° flows through the parallel orifices 34 and 3.
5, and as the oil pressure in the engagement side oil chamber B increases, the first brake b is quickly engaged.

On the other hand, during a 3rd and 2nd gear shift at a high vehicle speed, the spool 17b is in the position shown in the lower half, so the pressure oil in the release side oil chamber B is drained only through the orifice 35, and the first brake b1 is gradually activated. It is concluded. In this way, by delaying the engagement of the first brake b1 at high vehicle speeds and increasing the engine rotation, the shift shock during the 3-42 shift is alleviated.

The relief valve 18 is a valve that adjusts the oil pressure of the back pressure chamber tih of the regulator valve 11, and the spring 18
It has a spool 18b biased leftward by a spring 18a, and a throttle pressure Pt is introduced from a port 15p of a 1-2 shift valve 15 to a left end bow H8c in a direction facing the spring 18a. When the throttle pressure P7 input to the left end port 18c is less than the spring load of the spring 18a, the oil pressure in the back pressure chamber 11h is equal to the throttle pressure Pτ, and when the throttle pressure P exceeds the spring load of the spring 18a, relief occurs. Since the valve 18 drains, 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, line pressure P
L has a characteristic as shown in FIG.

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

First, in the 2nd speed state, the spring load of the spring 16a, the throttle pressure P input to the port 16i, and the boat 1
The line pressure PL input to 6e and 16h pushes the spool 16b to the right, and the governor pressure P, which opposes this, pushes the spool 16b to the left.

On the other hand, in the third speed state, the bow 1-16e is closed and the line pressure PL of the boat 16h does not apply a load to the spool 16b, so the spring load, throttle pressure P7, and kickdown pressure P3 input to the boat 16f are Push the spool 16b to the right to increase the governor pressure P.

is acting in opposition to this. In this way, line pressure PL acts in the same direction as throttle pressure P only in the 2nd gear state, and as shown in Figure 3, line pressure PL maintains a constant oil pressure even when the throttle is fully closed. As shown in Figure 7, a large hysteresis (+s) can be given between the downshift (3rd gear and 2nd gear) and upshift (2nd gear → 3rd gear) at the time of the shift.
In order to directly downshift to 1st gear (engine braking does not work in 1st gear in D range), the shift point of 3rd gear = 02nd gear when the throttle is fully closed is changed to 2 as shown in Figure 7.
Even when the vehicle speed is set to approximately the same as the shift point of L gear,
Since a large hysteresis HIff can be provided between 3rd gear and 2nd gear and 2nd gear and 3rd gear when the throttle is fully closed, running stability is improved.

The reason why the kickdown pressure PK is applied in the same direction as the throttle pressure P7 in the third gear is to improve the kickdown performance in a high vehicle speed range.

The same can be said of the ■-2 shift pulp 15.

In addition to being applied to the 2-3 shift valve 16 of an automatic transmission having three forward speeds as in the above embodiment, the present invention is also applicable to the 2-3 shift valve 16 of an automatic transmission having four or more forward speeds. The same applies to a 3-shift valve or a shift valve that switches between higher speed stages.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, line pressure is guided in the same direction as the throttle pressure only in the low speed gear for the shift valve that switches between the n speed and the n+1 speed (n≧2). Therefore, there is a large hysteresis between upshift and downshift in the low throttle range, and
Driving stability is improved.

Further, there is no need to provide a dedicated valve that generates a constant hydraulic pressure even when the throttle is fully closed, and the regulator valve can be used in common, resulting in the effect that the hydraulic circuit can be made into a cylinder.

[Brief explanation of the drawing]

FIG. 1 is a power transmission mechanism diagram of an automatic transmission according to the present invention;
Figure 2 is the hydraulic circuit diagram, Figure 3 is the line pressure characteristic diagram,
FIG. 4 is a characteristic diagram of throttle pressure, FIG. 5 is a characteristic diagram of kink-down pressure, FIG. 6 is a characteristic diagram of exhaust pressure, and FIG. 7 is a shift diagram. C,,C,...clutch, b,,B,...brake, 0-C...one-way clutch, 3...servo piston, 4...planetary gear mechanism, 11...regulator valve , 13...throttle valve, 14...governor valve, 16...23 shift valve, 18...
Relief valve. Patent applicant Daihatsu Motor Co., Ltd.

Claims (1)

[Scope of Claims] In an automatic transmission having three or more forward speeds, there is provided a governor valve that outputs governor pressure that increases in accordance with vehicle speed, and a throttle valve that outputs throttle pressure that increases in accordance with throttle opening. , a regulator valve that always outputs line pressure above a certain pressure, and a shift valve that supplies or discharges hydraulic pressure to a friction element and switches between n gear and n+1 gear (n≧2), On the other hand, a hydraulic control device for an automatic transmission characterized in that governor pressure and throttle pressure are guided in opposite directions, and line pressure is guided in the same direction as the throttle pressure only in n-speed.