JPH0578706B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a band brake engagement control device used as a shift element of an automatic transmission for an automobile.

(Prior Art) Conventionally, as a band brake engagement control device, for example, Japanese Patent Application Laid-open No. 13852/1983 and Japanese Patent Application Laid-open No. 62-13852
A device as described in Japanese Patent No.-63252 is known.

JP-A-62-13852 discloses that the kick-down brake is gradually released by reducing the hydraulic pressure in the servo apply pressure chamber of the servo piston at a predetermined rate of change using an electronic control device. Disclosed.

JP-A-62-63252 discloses a general band brake device.

(Problems to be solved by the invention) However, none of the conventional devices (in addition,
Even though the conventional device of No. 62-13852 is an invention related to brake release, when the brake is engaged, the brake release pressure may be released too quickly and a coupling shock may occur, or conversely, the brake release pressure may be released too late and the band may not be engaged. There was a concern that it would take a long time and cause problems such as significantly impairing the band fastening feeling.

That is, the basis for shifting gears is to apply an appropriate fastening force in a short period of time to reduce shock and to perform comfortable shifting. On the other hand, Clutch. Brakes require a certain amount of clearance to ensure safety when released and to reduce slipping resistance. Therefore, when tightening, the piston stroke to close this gap is a waste of time, and if it is long, it will not be possible to perform a comfortable shift, and it will also be a hindrance to accurate control.

Therefore, in order to reduce this effect, if the cross-sectional area of the flow path of the servo apply pressure circuit is increased and the servo apply pressure circuit is fastened, a large impact hydraulic pressure will be instantaneously generated on the overshoot side at the end of the piston stroke, resulting in a fastening shock.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this purpose, the present invention provides the following solving means. And so.

That is, as shown in the conceptual diagram of the claim in FIG. 1, there is a pressure receiving part d to which operating pressure is supplied from the servo apply pressure circuit c in order to generate a fastening force for the brake band b, and a pressure receiving part d to release the brake band b. The servo piston a includes a pressure receiving portion f to which release pressure is supplied from a servo release pressure circuit e, and the servo release pressure circuit e is a first circuit having a constant small opening area g at least in the withdrawal direction. h, and a second circuit j in parallel with the first circuit h.
and a switching valve i that can be opened and closed by an external signal in the second circuit j. Valve opening/closing control means k which opens and closes the switching valve i only for a predetermined period of time from when the servo piston a starts its stroke and from immediately before the end of the stroke until the end of the stroke when the band brake is engaged during a gear shift supplying the servo piston a. It is characterized by having

(Function) When the band brake is engaged during gear shifting,
The servo piston a starts to stroke due to the supply of operating pressure from the servo apply pressure circuit c.
Until just before the end of the stroke, the switching valve i is kept open by a command from the valve opening/closing control means k, so that the oil discharge on the servo release side accompanying the stroke of the servo piston a is controlled by the servo release pressure circuit e. Of the first circuit h and second circuit j, the flow is carried out in a short time after passing through the second circuit j, which has a larger flow path cross-sectional area.

Then, when the servo piston a reaches just before the end of its stroke, the switching valve i is changed from open to closed only for a predetermined period of time until the end of the stroke by a command from the valve opening/closing control means k, so that the servo release side The oil is discharged through a first circuit h having a constant small opening area g at least in the withdrawal direction.

By regulating the escape flow rate by this small opening area g, a brake is applied to the stroke of the servo piston a, and residual pressure is generated in the servo release pressure chamber, which has a cushioning effect, and in the servo apply pressure chamber. Hydraulic pressure from the servo release pressure chamber acts in a direction that cancels out the instantaneous overshoot that occurs when the piston ends, thereby alleviating the shock when the brake band b is fastened.

Therefore, by simple control, a comfortable shift can be achieved in which the band is tightened in a short time while preventing the band tightening shock.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

First, the configuration will be explained.

The band brake engagement control device A of the embodiment is as follows:
As shown in Fig. 2, this is applied to a band brake 1 which is a shift element (clamping element) of an automatic converter that is released in 1st gear and engaged in 2nd gear. 1←→2 shift valve 4 to generate the tightening force of the brake band 3
a pressure receiving part 2a where operating pressure from the line pressure P _L is supplied from the servo apply pressure circuit 5 to the servo apply chamber 6 via the servo apply pressure circuit 5; Line pressure P _L from 8 to servo release pressure chamber 9
and a pressure receiving portion 2b to which release pressure is supplied.

Incidentally, the band brake 1 includes a rotating drum 10.
A transmission element that stops the rotating drum 10 relative to the case 11 by fastening the brake band 3 wound above.The fixed end of the brake band 3 is supported by the anchor end pin 12, and the movable end is supported by the servo piston 2. The piston stem 13 is supported by a piston stem 13 fixed to the piston stem 13, and is fastened when the piston stem 13 strokes upward in the drawing. Further, the servo piston 2 has a return spring 14 provided within the piston cylinder and biased in the releasing direction.

The servo release pressure circuit 8 includes a first circuit 8 having an orifice 15 (certain small opening area).
1 (first circuit) and a second circuit 8 having a timing valve 16 (switching valve) that can be opened and closed by an external signal.
2 (second circuit) and a third circuit 83 having a one-way valve 17 that allows flow only from the bottom to the top in the drawing.

The timing valve 16 is provided with a spring 16a at one end, and a pilot pressure oil chamber 1 at the other end.
6b is provided with a spool 16c, and when the pilot pressure P _P is not supplied,
Due to the biasing force of the spring 16a, it is in the solid line position in the drawing, blocking ports 82a and 82b, and when pilot pressure P _P is supplied, it moves to the dotted line position in the drawing, allowing both ports 82a and 82b to communicate with each other.

Note that a clutch pressure circuit 19 is branched from the servo release pressure circuit 8 to a direct coupling clutch 18 as another speed change element.

The timing valve 16 includes a valve that opens and closes the timing valve 16 only for a predetermined period of time from when the servo piston 2 starts its stroke and immediately before the end of the stroke when the band is engaged when shifting from 1st speed to 2nd speed. It has a solenoid valve 20 as an opening/closing control means.

This solenoid valve 20 determines predetermined opening and closing conditions in a speed change control circuit 21 using an electronic control circuit, and operates based on a command based on this determination. When the solenoid valve 20 is closed, the timing valve 16 is opened. , when the solenoid valve 20 is open, the timing valve 16 is closed.

Next, the effect will be explained.

First, when shifting from 1st gear to 2nd gear, the shift control circuit 2
The flow of the engagement control operation of the band brake 1 performed in step 1 will be explained with reference to the flowchart shown in FIG.

When the information that it is time to shift from 1 to 2 is provided in step 100, a valve closing command is issued from the shift control circuit 21 to the solenoid valve 20 in step 101, and the solenoid valve 20 is closed.

Then, in step 102, the servo piston 2
It is determined whether a predetermined condition indicating that the stroke has started and the stroke is about to end is satisfied.

Note that the predetermined conditions refer to conditions listed below.

-a A predetermined period of time has elapsed since the 1→2 shift command.

Here, the predetermined time period includes a plurality of time periods set using parameters such as accelerator opening degree and temperature.

-b When the stroke of servo piston 2 reaches a predetermined value.

-c When the oil pressure of the servo apply pressure circuit 5 reaches a predetermined value.

Therefore, from the 1→2 speed change command, the servo piston 2
Until just before the end of the stroke, the solenoid valve 20
remains closed, and the timing valve 16 closes both ports 8.
2a and 82b are maintained in an open state in communication.

If the predetermined conditions are satisfied in step 102, the process proceeds to step 103, where the speed change control circuit 21 issues an open command to the solenoid valve 20, and the solenoid valve 20 opens.

Then, in step 104, the servo piston 2
It is determined whether or not a predetermined condition indicating that the stroke has reached the end from just before the end of the stroke is satisfied.

Note that the predetermined conditions refer to conditions listed below.

-a A predetermined period of time has elapsed since the solenoid valve 20 was opened.

Here, the predetermined time includes a plurality of times set using parameters such as accelerator opening and oil temperature.

-b A predetermined elapsed time after the stroke of the servo piston 2 exceeds a predetermined value.

-c A predetermined elapsed time after the oil pressure of the servo apply pressure circuit 5 exceeds a predetermined value.

Therefore, from just before the end of the stroke of the servo piston 2 until the end of the stroke, the solenoid valve 20
remains open, and the timing valve 16 opens both ports 8
2a and 82b maintain the closed state.

When the predetermined conditions are satisfied in step 104, the process proceeds to step 105, where the shift control circuit 21 issues a valve closing command to the solenoid valve 20, and the solenoid valve 20 is closed.

Next, the operation at 1st speed and when shifting from 1st to 2nd speed will be explained.

(B) At 1st speed When in 1st speed such as D range, port 4a of 1←→2 shift valve 4 is also connected to port 7 of 2←→3 shift valve 7.
a also communicates with drain ports 4b and 7b,
Servo release pressure chamber 9 also goes to servo apply pressure chamber 6
Furthermore, the line pressure P _L is also applied to the direct coupling clutch 18.
There is no supply of.

Therefore, the servo piston 2 is biased by the return spring 14, and the band brake 1 , which remains in the lower position in the figure, is released. Further, the direct coupling clutch 18 is also released.

(b) When shifting from 1st gear to 2nd gear When automatically shifting from 1st gear to 2nd gear in D range etc. depending on vehicle speed conditions, accelerator opening conditions, etc., the 1←→2 shift valve 4 is shifted by a command from the shift control circuit 21. The spool is moved so that port 4a communicates from drain port 4b to line pressure port 4c,
Supply of hydraulic oil at line pressure P _L to the servo apply pressure chamber 6 is started.

On the other hand, from the speed change control circuit 21, the step
As shown at 101, a command to close the solenoid valve 20 is output.

Therefore, by supplying line pressure to the servo apply pressure chamber 6, the servo piston 2 starts to stroke upward in the drawing, and along with this stroke, the hydraulic oil at the drain pressure filled in the servo release pressure chamber 9 is discharged. , both ports 82 of the servo release pressure oil passage 8
a, 82b (second circuit 82), the port 7a of the 2←→3 shift valve 7, and the drain port 7b, and is discharged in a short time.

Then, when the servo piston 2 reaches the end of its stroke, a command to open the solenoid valve 20 is output from the speed change control circuit 21, and the hydraulic fluid in the servo release pressure chamber 9 passes through the orifice 15 by shutting off the timing valve 16. Then, it is discharged from the first circuit 81.

By regulating the flow rate through the orifice 15, a brake is applied to the servo piston 2, residual pressure is generated in the servo release pressure chamber 9, which has a cushioning effect, and the piston stroke generated in the servo apply pressure chamber 6 ends. Hydraulic pressure from the servo release pressure chamber 9 acts in a direction that cancels out the momentary overshoot at the time, thereby alleviating the shock at the time of band fastening.

When the servo piston 2 reaches the stroke end region, the solenoid valve 20 is activated again in order to secure the torque transmission capacity and realize a non-slip band fastening state.
is closed.

Incidentally, the time change characteristics of the servo apply pressure P _A in the servo apply pressure chamber 6 and the time change characteristics of the servo release residual pressure P _R in the servo release pressure chamber 9 when the band is fastened are as shown in Fig. 4. It can be seen that a residual pressure P _R is generated in the servo release pressure chamber 9 so as to cancel out the instantaneous overshoot of the servo apply pressure P _A at the end of the piston stroke.

As explained above, in the band brake engagement control device A of the embodiment, when the brake is engaged, instead of complex hydraulic control on the servo apply pressure side, which is the engagement force of the band brake 3, the servo release pressure side is used. With simple ON/OFF control, the band can be fastened in a short time while preventing a fastening shock, thereby achieving comfortable gear shifting.

Although the embodiments have been described above based on the drawings, the specific configuration is not limited to these embodiments, and even changes in design within the scope of the gist of the present invention are included in the present invention. .

For example, in the embodiment, a timing valve with a solenoid valve at a remote location is shown as a switching valve, but
A solenoid valve or the like that is opened and closed directly by electromagnetic force may also be used.

(Effects of the Invention) As described above, in the band brake engagement control device of the present invention, the servo release pressure circuit includes a first circuit having a constant small opening area at least in the release direction; A second circuit is provided in parallel with the first circuit and has a switching valve that can be opened and closed by an external signal. Since the structure includes a valve opening/closing control means that opens and closes the switching valve only for a predetermined period of time from just before the end of the stroke to the end of the stroke, the tightening force of the brake band is reduced when the brake is engaged. Instead of complex hydraulic control on the servo apply pressure side, simple ON-OFF control on the servo release side allows for fast engagement while preventing engagement shocks, which allows for comfortable gear shifting. The effect is that it can be achieved.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of a claim showing a band brake engagement control device of the present invention, Fig. 2 is an overall diagram showing a band brake engagement control device of an embodiment, and Fig. 3 is a shift control circuit of an embodiment of the engagement control device. 1 → 2
FIG. 4 is a flowchart showing the flow of control operations during gear shifting, and FIG. 4 is a time chart of servo apply pressure and servo release residual pressure during band engagement of the embodiment engagement control device. a... Servo piston, b... Brake band, c... Servo apply pressure circuit, e... Servo release pressure circuit, f... Pressure receiving portion, g... Small opening area portion, h... First circuit, i...Switching valve, j...
...Second circuit, k...Valve opening/closing control means.

Claims (1)

[Scope of Claims] 1. A pressure receiving part d to which operating pressure is supplied from the servo apply pressure circuit c to generate a fastening force for the brake band b, and a pressure receiving part d to which operating pressure is supplied from the servo release pressure circuit e to release the front brake band b. The servo release pressure circuit e has a pressure receiving part f to which pressure is supplied, and a servo piston a consisting of: a first circuit h having a constant small opening area g at least in the withdrawal direction; A band brake engagement control device comprising: a second circuit j parallel to the circuit h; and the second circuit j includes a switching valve i that can be opened and closed by an external signal. When the band brake is engaged during gear shifting to supply operating pressure to the servo apply pressure circuit c, the switching valve i is activated only for a predetermined period of time from when the servo piston a starts its stroke and from immediately before the end of the stroke until the end of the stroke. A band brake engagement control device characterized by having a valve opening/closing control means k for switching from opening to closing.