JP3131893B2 - Device for unlocking servo valve in hydraulic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric actuator for generating an operating force corresponding to an operating force of a master cylinder, a valve box having an input port, an output port and a discharge port, and a slidable valve. The input port and the output port are cut off between the output port and the discharge port from the valve closing position where the input port and the output port are disconnected and the output port and the discharge port are communicated by the operating force of the electric actuator. And a spool valve having a valve body that slides to a valve opening position that communicates between them, and a servo valve, wherein a hydraulic supply source is connected to the input port, and a hydraulic actuator is connected to the output port. And a lock release device for a servo valve.

[0002]

2. Description of the Related Art In a hydraulic braking system for an automobile, if the hydraulic pressure of a hydraulic supply source is set as high as possible, even a relatively compact wheel brake having an oil chamber can exert a large braking force. The brake can be made more compact. However, when the oil pressure of the oil pressure supply source becomes higher than a certain value, the spool phenomenon of the servo valve tends to cause a locking phenomenon in a closed state. That is, in the closed state of the spool valve, a large pressure difference between the high-pressure input port and the low-pressure discharge port causes pressure oil to leak on one side of the spool valve body, and as a result, a large amount of pressure oil leaks into the spool valve body. When this state continues for a long time, a hydraulic lock phenomenon may occur. According to such a locking phenomenon, there arises a disadvantage that the spool valve does not open when the solenoid is energized, or the opening of the spool valve is significantly delayed.

[0003]

In order to solve the above-mentioned problem, an on-off valve is interposed in a communication passage between the input port of the spool valve and the hydraulic supply source, and the on-off valve is closed when the electric actuator is not operated. There has been known a spool valve in which the entire inside thereof is maintained at a low pressure (Japanese Patent Laid-Open No. 4-1 / 1991).
No. 07369).

However, in the above-mentioned conventional apparatus, when the electric actuator is not operated, that is, when the spool valve is closed, the pressure is maintained at a low pressure up to the input port. Even if the valve is opened immediately, there is some time delay before the oil pressure of the oil pressure supply fills the input port, which causes a decrease in the responsiveness of the hydraulic actuator.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an unlocking device for a servo valve which can release a locking phenomenon of a spool valve without deteriorating the responsiveness of a hydraulic actuator. And

[0006]

In order to achieve the above-mentioned object, the present invention is formed on a valve box of a spool valve,
A hydraulic oil chamber capable of displacing the valve body in the valve opening direction, an output chamber communicating with the hydraulic oil chamber, and an input chamber communicating with the output port of the master cylinder, with both end faces of the piston facing each other,
A pressure increasing means for biasing the piston toward the retreat limit of the input chamber side, and the output chamber communicates with the reservoir when the piston is located at the retreat limit. When the vehicle moves forward, there is provided a valve means for interrupting the communication of the output chamber with the reservoir at an early stage of the forward movement, and then reconnecting the output chamber to the reservoir when the vehicle travels a predetermined stroke or more.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention shown in FIG. 1 will be described. The piston 3 of the master cylinder M is connected to the brake pedal 1 via a push rod 2. The output port 4 of the master cylinder M is connected to the first inlet 6 of the electromagnetic switching valve 5.
Connected _1, the outlet 7 of Doben 5 is connected to the wheel brake B (hydraulic actuator). The second inlet 6 ₂ Doben 5 is connected to the output port 9 of the servo valve S. Switching valve 5 is in a demagnetized state is adapted to communicate between the first inlet ₆₁ and communicates between the outlet 7 and is energized second inlet 6 ₂ and the outlet 7. Excitation state of the switching valve 5, i.e. when during the first inlet 6 ₁ and an outlet 7 is in the cutoff state, the stroke accumulators As for securing the depression stroke of the brake pedal 1 by accumulating the output hydraulic pressure of the master cylinder M is It is connected to an oil passage between master cylinder M and switching valve 5.

A hydraulic pressure source P is connected to the input port 8 of the servo valve S, and a reservoir 11 is connected to a discharge port 10 of the valve S.

A hydraulic supply source P includes a hydraulic pump 12 for pumping hydraulic oil from a reservoir 11, an accumulator 13 connected to the discharge side of the hydraulic pump 12, and a hydraulic pump 1
2 for controlling the operation of the pressure switch 2.

The push rod 2 has a tread force sensor 1 for detecting the amount of tread force applied to the brake pedal 1.
The output signal of the pedaling force sensor 17 is input to a control unit 18. The control unit 18 converts the input signal into an electric quantity and applies it to the servo valve S.

A brake sensor 19 for detecting an operation state of the brake pedal 1 is provided opposite to the brake pedal 1, and an output signal of the brake sensor 19 is input to a control unit 18. The control unit 18 normally excites the switching valve 5 upon receiving a signal from the brake sensor 19, but upon receiving an output signal from the failure sensor 20 for detecting a failure of the hydraulic supply P or the servo valve S, brakes. The signal from the sensor 19 is invalidated.

The servo valve S has a linear solenoid 21
And a spool valve 22 continuously provided thereunder. The linear solenoid 21 is connected to the control unit 18.
Of the spool valve 22 according to the amount of electricity applied from the
3 is provided with an output rod 24 that exerts a downward electromagnetic thrust.

The spool valve 22 is provided with a valve box 25 having the input / output ports 8, 9 and the discharge port 10, and the valve body 2 fitted in a valve hole 25a of the valve box 25 so as to be able to move up and down.
3 and a valve spring 26 for urging the valve body 23 in the ascending direction. When the valve body 23 occupies the closing position at the ascending limit, the input port 8 is shut off and the output port 9 is discharged. The valve is opened to the port 10, but when the valve element 23 is lowered, the discharge port 10 is shut off and the port is opened to communicate between the output ports 8 and 9, and as the valve element 23 descends, the communication opening increases. ing.

A reaction chamber 27 is formed in the valve hole 25a and faces the lower end face of the valve element 23. The reaction chamber 27 communicates with the output port 9. Therefore, in the reaction force chamber 27, an upward reaction force due to the oil pressure is generated in the valve body 23 in response to the increase in the oil pressure of the output port 9.

The valve box 25 is provided with an unlocking device 28 for the valve element 23 as follows.

That is, the device 28 includes the linear solenoid 2
1 and a valve body 23, a hydraulic oil chamber 29 defined in a valve hole 25a.
A pressure increasing means 30 for increasing the pressure of the hydraulic oil chamber 29 by the output oil pressure of the master cylinder M; and a valve means 31 for limiting the pressure increasing action of the pressure increasing means 30 to a certain degree.

The pressure raising means 30 has a cylinder hole 32 provided in the valve box 25 adjacent to the valve hole 25a, and is slidably fitted in the cylinder hole 32 so that the input chamber 33 and the output chamber 33 The piston 35 is divided into a chamber 34 and a return spring 36 contracted to the output chamber 34 to urge the piston 35 toward the input chamber 33. The retraction stopper 37 that regulates
Further, the output chamber 34 is provided with a forward stopper 38 for regulating the forward limit of the piston 35. And input room 3
The output chamber 3 is connected to the output port 4 of the master cylinder M so as to communicate with the output port 3, and the output chamber 34 communicates with the hydraulic oil chamber 29 through the through hole 39.

The valve means 31 is provided at a cylindrical valve portion 35a formed at the front end of the piston 35 so as to face the output chamber 34 at the front surface, and at an intermediate portion of the piston 35 adjacent to the rear portion of the valve portion 35a. An annular groove 35b that always communicates with the output chamber 34, and a relief port 40 that opens on the inner surface of the cylinder hole 32 so as to be opened and closed by the valve portion 35a, and the relief port 40 communicates with the reservoir 11. Connected. Thus, the valve portion 35a opens the relief port 40 when the piston 25 is located at the retreat limit, but closes the port 40 at the initial stage of the advance of the piston 35, and after closing the port 40, the piston 35 If the port 4 is advanced by a predetermined stroke equal to the axial width of the valve portion 35a, the port 4
0 is communicated with the annular groove 25b so as to open again. The predetermined stroke of the piston 35 is set to an amount by which the valve body 23 is slightly displaced to near the valve opening start point due to the pressure increase of the hydraulic oil chamber 29 caused by the piston 35 moving forward.

Next, the operation of the first embodiment will be described.

If the master cylinder M is inactive, the switching valve 5 and the servo valve S are all demagnetized. Since the demagnetized switching valve 5 disconnects the wheel brake B from the output port 9 of the servo valve S and communicates with the master cylinder M, the oil chamber of the wheel brake B stores the reservoir of the master cylinder M. Open to the public. Further, in the servo valve S, the valve spring 26 pushes the valve element 23 up to the ascending limit and shuts off the input port 8. Press one side. If such a state continues for a long time, a phenomenon of hydraulic lock of the valve body 23 may occur.

On the other hand, in the lock release device 28, since the master cylinder M does not generate the output hydraulic pressure, the piston 35 is held at the retreat limit by the urging force of the return spring 36 (the state shown in FIG. 1). The hydraulic oil chamber 29 of the spool valve 22 communicates with the reservoir 11 via the output chamber 34 and the relief port 40.

Here, when the master cylinder M is operated by depressing the brake pedal 1 in order to perform braking, the output oil pressure is transmitted to the input chamber 33 of the unlocking device 28, and the piston 35 is advanced by the oil pressure. . Then, since the valve portion 25a of the piston 25 immediately closes the relief port 40, the hydraulic pressure generated in the output chamber 34 due to the subsequent advance of the piston 35 is transmitted to the hydraulic oil chamber 29 through the through hole 39, and the oil chamber 29 is The pressure is increased, and the valve body 23 is forcibly displaced downward. Therefore, even if the valve element 23 is in the hydraulic lock state at its upper limit, the hydraulic lock state is released by the forcible displacement as described above.

As shown in FIG. 2, when the valve body 23 descends to the vicinity of the valve opening start point, the piston 35
b is communicated to the relief port 40, and the communication state is maintained while the piston 35 reaches the forward limit, so that during the operation of the master cylinder M, the output chamber 34 and the hydraulic oil chamber 2
The hydraulic pressure of No. 9 is released to the reservoir 11 via the annular groove 35b and the relief port 40.

On the other hand, the control unit 18 receives a signal from the brake sensor 19 to excite the switching valve 5, and shuts off between the master cylinder M and the wheel brake B by switching the valve. 9 and the wheel brake B. Subsequently, the linear solenoid 2 of the servo valve S is supplied with an electric quantity according to the output signal of the pedaling force sensor 17.
When the output rod 24 pushes the valve body 23 downward with a thrust corresponding to the pedal depression force, the valve body 23 that has already been released from the locked state as described above is connected between the input port 8 and the output port 9. Can be immediately moved to the valve-opening position where the valve communicates. In addition, since the hydraulic pressure of the hydraulic pressure source P always fills the input port 8 and stands by, the hydraulic pressure is immediately output from the output port 9 when the valve body 23 is opened,
It is transmitted to the wheel brake B without delay, and it is operated reliably.

Next, when the pedaling force is released from the brake pedal 1, the output oil pressure of the master cylinder M decreases, and the piston 35 of the unlocking device 28 immediately returns to the retreat limit by the resilience of the return spring 36, thereby releasing the relief port. Since the valve 40 is opened again, the return operation of the spool valve 22 to the upper limit is not prevented.

At the time of braking, if the hydraulic supply source P or the servo valve S is out of order, the control unit 18 receives the signal from the fault sensor 20 and holds the switching valve 5 at the original position. Can be directly transmitted to the wheel brake B via the switching valve 5, and fail-safe is ensured.

FIG. 3 shows a second embodiment of the present invention.
The configuration is the same as that of the previous embodiment except that the relief port 40 communicates with the discharge port 10. In the figure, the same reference numerals are given to the corresponding parts in the previous embodiment.

According to this embodiment, the connecting portions of the flow passage connected to the reservoir 11 to the relief port 40 and the discharge port 10 can be integrated at one place.

In each of the above embodiments, various design changes can be made without departing from the gist of the present invention. For example, a motor can be used instead of the linear solenoid 21. Also, the input / output chambers 33 and 34 and the piston 35
Can be separated from the servo valve S, and the output chamber 34 and the hydraulic oil chamber 29 can be communicated by a pipe.

[0031]

As described above, according to the present invention, the hydraulic oil chamber formed in the valve casing of the spool valve and capable of displacing the valve body in the valve opening direction at the time of pressure increase, and the output communicating with the hydraulic oil chamber. Boosting means comprising a piston and both ends facing the input chamber communicating with the chamber and the output port of the master cylinder, and biasing the piston toward the retreat limit of the input chamber, and the piston is located at the retreat limit. When the output chamber communicates with the reservoir,
When the piston moves forward due to the pressure increase of the input chamber due to the output hydraulic pressure of the master cylinder, the communication with the reservoir of the output chamber is cut off at the initial stage of the advance, and then, when the piston advances more than a predetermined stroke, the output chamber communicates with the reservoir again. With this arrangement, it is possible to forcibly displace the valve body of the spool valve by the output hydraulic pressure and release the hydraulic lock in the early stage of the operation of the master cylinder. Can be done. Moreover, since the input port is always filled with the hydraulic pressure of the hydraulic supply source, when the valve is opened, the hydraulic pressure can be immediately output from the output port to operate the hydraulic actuator without delay.

[Brief description of the drawings]

FIG. 1 is an overall view of a hydraulic brake system for a vehicle according to a first embodiment of the present invention, in which a servo valve is longitudinally cut.

FIG. 2 is an operation explanatory view of FIG. 1;

FIG. 3 is an overall view similar to FIG. 1, showing a second embodiment of the present invention;

[Explanation of symbols]

 B Wheel brake (hydraulic actuator) L Predetermined stroke M Master cylinder S Servo valve P Hydraulic supply 8 Input port 9 Output port 10 Drain port 11 Reservoir 21 Linear solenoid (electric actuator) 22 Spool valve 23 Valve body 25 Valve box 28 Lock release Apparatus 29 Hydraulic oil chamber 30 Boost means 31 Valve means 35 Piston 40 Release port

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T 15/36 B60T 13/12-13/20 F16K 31/06 305

Claims (1)

(57) [Claims] An electric actuator (21) for generating an operating force according to an operating force of a master cylinder (M), an input port (8), an output port (9), and a discharge port (1).
0), and the valve box (25) is slidably disposed on the valve box (25), and cuts off between the input port (8) and the output port (9) by the operating force of the electric actuator (21). Then, from the valve-closing position communicating between the output port (9) and the discharge port (10), the connection between the output port (9) and the discharge port (10) is cut off to connect the input port (8) and the output port (9). (2) that slides to the valve opening position
3) constitute a servo valve (S) with a spool valve (22) having a hydraulic supply (P) at the input port (8) and a hydraulic actuator (B) at the output port (9). A hydraulic oil chamber (29) formed in a valve box (25) of a spool valve (22) and capable of displacing a valve body (23) in a valve opening direction when the pressure is increased. Output chamber (34) communicating with oil chamber (29) and output port (4) of master cylinder (M)
Boosting means (30) having both ends of the piston (35) facing the input chamber (33) communicating with the piston and biasing the piston (35) toward the retreat limit of the input chamber (33).
When the piston (35) is located at the retreat limit, the output chamber (34) communicates with the reservoir (11), but the piston (35) is raised by the pressure increase of the input chamber (33) by the output oil pressure of the master cylinder (M). When the vehicle moves forward, the communication between the output chamber (34) and the reservoir (11) is cut off at the beginning of the forward movement, and when the vehicle moves forward by a predetermined stroke (L) or more, the output chamber (3) moves forward.
Valve means (3) for reconnecting the reservoir (4) to the reservoir (11).
(1) An unlocking device for a servo valve in a hydraulic operating device, comprising: