JP3168110B2 - Lock prevention device for 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 in accordance with an input, a housing having an input port, an output port and a discharge port, and an electric actuator slidably disposed in the housing. With the actuation force of the above, from the valve closing position where the input port and the output port are shut off and the output port and the discharge port are communicated, the valve between the output port and the discharge port is shut off and the input port and the output port are communicated. A spool valve including a spool valve body having a spool valve body that is operated to a position, a hydraulic valve being connected to the input port, and a hydraulic actuator connected to the output port. It relates to a prevention device.

[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 a pressure oil leak on one side of the spool valve body, and as a result, a large amount of oil leaks into the spool valve body. When this state continues for a long time, a locking 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.

In order to solve the above problem, an on-off valve is interposed in a communication passage between the input port of the spool valve and the hydraulic pressure supply source, and the on-off valve is closed when the electric actuator is not operated, so that the entire interior of the spool valve is closed. A device in which the pressure is maintained at a low level is conventionally known (see Japanese Patent Application Laid-Open No. 4-107369).

[0004]

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. When the valve is opened, even if the opening / closing valve is opened immediately, there is some time delay until the hydraulic pressure of the hydraulic supply source 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 a servo valve lock prevention device capable of preventing a lock phenomenon of a spool valve without deteriorating the responsiveness of a hydraulic actuator. And

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a discharge port and a hydraulic supply between an exhaust port of a spool valve and a hydraulic supply and a reservoir when the electric actuator is not operated. A switching valve is provided to connect the discharge port and the reservoir during operation, and is opened / closed between the output port of the spool valve and the hydraulic actuator according to the activation / deactivation of the electric actuator. A cut valve is provided.

[0007]

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

First, from the first embodiment of the present invention shown in FIG.
explain. FIG. 1 shows a vehicle braking system to which the present invention is applied.
It is an overall view. Referring to FIG.
Piston 3 of the master cylinder M via the brush rod 2
Are connected. Output port 4 of master cylinder M is electromagnetic
First inlet 6 of the switching cut valve 5₁Connected to the same valve 5
Outlet 7 is in contact with wheel brake B (hydraulic actuator).
Continued. The second inlet 6 of the valve 5_TwoIs the servo valve S
Is connected to the output port 9. Switching cut valve 5 is demagnetized
In the state, the first entrance 6₁And between the outlet 7 and excited
Then the second entrance 6 _TwoAnd between the exit 7
I have. Excited state of the switching cut valve 5, that is, the first inlet 6₁Passing
The master cylinder M
Accumulates the output hydraulic pressure of the brake pedal 1 and
Stroke actuator As to secure the stroke
Is the output port 4 of the master cylinder M and the switching cut valve
5 is connected.

A hydraulic supply P is connected to an input port 8 of the servo valve S, and a hydraulic supply P and a reservoir 1 are connected to a discharge port 10 of the valve S via an electromagnetic switching valve 15.
1 is connected.

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.

[0011] The switching valve 15 has a first port 16 _1, the third port 16 ₃ communicating with the exhaust port 10 of the second port 16 ₂ and the servo valve S which communicates with the reservoir 11 communicating with the accumulator 13 , in the demagnetized state the first and third ports 1 blocks the ₂ second port 16
6 ₁ , 16 ₃ are connected to each other.
₁ is shut off to allow communication between the second and third ports 16 ₂ and 16 ₃ .

The push rod 2 has a tread force sensor 1 for detecting the amount of tread force applied to the brake pedal 1.
An 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 the operating 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. When the control unit 18 receives a signal from the brake sensor 19 during normal times, the switching cut valve 5 and the switching valve 1
When the output signal of the failure sensor 20 for detecting a failure of the hydraulic pressure supply source P or the servo valve S is received, the signal from the brake sensor 19 is invalidated.

The servo valve S includes a spool valve 21
And a linear solenoid 22 (electric actuator) connected to the upper part of the linear solenoid. Spool valve 21
Is a housing 23, a valve cylinder 24 fitted to the housing 23, a spool valve element 25 fitted to the valve cylinder 24 so as to be able to move up and down, and a return for urging the spool valve element 25 in the ascending direction. The housing 23 has the input port 8, the output port 9 and the discharge port 10 provided with springs 26 ₁ and 26 ₂ . When the spool valve element 25 occupies the upper limit closing position, the spool valve 21 shuts off the input port 8 and opens the output port 9 to the discharge port 10, but the spool valve element 25 Then
The discharge port 10 is shut off to allow communication between the input port 8 and the output port 9, and the opening increases as the valve body 25 descends.

A reaction force device 27 for applying an upward reaction force to the spool valve body 25 in accordance with an increase in the hydraulic pressure of the output port 9 is provided below the valve cylinder 24.

The linear solenoid 22 includes a cylindrical outer yoke 28 connected to the housing 23, an end yoke 29 fixed to the upper end of the outer yoke 28, and a fixed core fixed to the lower end of the outer yoke 28. 30, a coil 31 disposed in an outer peripheral yoke 28, a movable core 32 opposed to the fixed core 30 and fitted to the end yoke 29 so as to be able to move up and down, and fixed to the movable core 32 and And an operating rod 33 projecting from both end surfaces.
3 is supported by the end yoke 29 and the fixed core 30 via a pair of upper and lower ball bearings 34 and 35 so as to be able to move up and down, and abuts on the upper end of the spool valve body 25. Thus, the linear solenoid 22 generates an electromagnetic force proportional to the amount of electricity applied to the coil 31 between the fixed core 30 and the movable core 32, and applies a downward thrust to the operating rod 33. I have.

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

If the master cylinder M is inactive, the switching cut valve 5, the switching valve 15, and the linear solenoid 22 of the servo valve S are all demagnetized. Thus, the switching cut valve 5 in the demagnetized state disconnects the wheel brake B from the output port 9 of the servo valve S and communicates with the master cylinder M, so that the oil chamber of the wheel brake B is connected to the reservoir of the master cylinder M. Be released. In addition the switching valve 15 of the demagnetized state, blocks the second port 16 ₂ communicating between the first and third ports 16 _1, 16 _3, the servo valves S demagnetization state, blocking the input port 8, Output port 9
And the discharge port 10.

Therefore, at this time, if the hydraulic pressure source P is operating normally, the hydraulic pressure directly acts on the input port 8 of the servo valve S, and the first and second ports 16 ₁ , 16 of the switching valve 15. _It acts from the discharge port 10 of the servo valve S to the output port 9 through ₂ . As a result, the entire inside of the spool valve 21 of the servo valve S is
And the pressure difference from the periphery of the spool valve element 25 is removed, so that even if this state continues for a long time, the spool valve element 25 does not experience the hydraulic lock phenomenon.

In addition, the output port 9 of the servo valve S
Is the wheel brake B by the switching cut valve 5 as described above.
, The hydraulic pressure in the servo valve S does not act on the wheel brake B.

Here, when the master cylinder M is actuated by depressing the brake pedal 1 to perform braking, the control unit 18 first receives the signal from the brake sensor 19 and switches the switching cut valve 5 and the switching valve 15. When the switching cut valve 5 is excited, the connection between the master cylinder M and the wheel brake B is cut off, the output port 9 of the servo valve S and the wheel brake B are connected, and the switching of the switching valve 15 causes the servo valve S to switch. Is disconnected from the hydraulic pressure supply source P, and is communicated with the reservoir 11.

Subsequently, when the linear solenoid 22 of the servo valve S is energized by an electric quantity corresponding to the output signal of the pedaling force sensor 17 and the operating rod 33 presses the spool valve body 25 with a thrust corresponding to the pedaling force, the lock state is established. Not the valve body 25
Promptly connects the input port 8 and the output port 9 with each other immediately. In addition, since the oil pressure of the oil pressure supply source P always fills the input port 8 and is on standby, the oil pressure is immediately output from the output port 9 and transmitted to the wheel brake B without delay, so that it is reliably operated.

During braking, when the spool valve body 25 is displaced upward to reduce the output oil pressure of the output port 9, the opening between the input port 8 and the output port 9 is reduced. Since the ports 10 are slightly communicated with each other, the hydraulic pressure is appropriately released from the output port 9 to the reservoir 11 through the discharge port 10, and the output hydraulic pressure at the output port 9 decreases.

Next, when the pedaling force is released from the brake pedal 1, the control unit 18 returns the switching cut valve 5, the switching valve 15 and the servo valve S to the initial demagnetized state.
In the servo valve S, the hydraulic pressure of the hydraulic pressure source P is filled again.

At the time of braking, if the hydraulic pressure source P or the servo valve S has failed, the control unit 18 receives the signal from the failure sensor 20 and holds the switching cut valve 5 at the original position. M output oil pressure can be directly transmitted to the wheel brake B via the switching cut valve 5,
Fail safe is ensured.

Next, a second embodiment of the present invention will be described with reference to FIG.

A free piston device 38 (hydraulic actuator) is provided between the output port 9 of the servo valve S and the wheel brake B. This device 38 has a cylinder hole 39 formed in a lateral extension 23a of the housing 23 of the servo valve S, and slidably fits into the cylinder hole 39 to form a first and second oil chamber 39 therein. _1, includes a 39 _second free piston 40 which divides into two chambers, and a spring 41 return biasing the second oil chamber 39 _{and second} free piston 40 is accommodated in the first oil chamber 39 _1. The first oil chamber 39 ₁ is connected to the output port 9 of the servo valve S via a normally-closed cut valve 42 of the electromagnetic, and the second oil chamber 39 ₂ is communicatively connected to the wheel brake B.

On the other hand, the output port 4 of the master cylinder M
Is connected to the wheel brake B via an electromagnetic type normally-open cut valve 43. The two cut valves 42 and 43 are excited by the control unit 18 when the brake sensor 19 issues a signal. Other configurations are the same as the previous embodiment,
In the figure, parts corresponding to those of the previous embodiment are denoted by the same reference numerals.

In the operation of the second embodiment, when the master cylinder M is not operated, that is, when the linear solenoid 22 is in a demagnetized state, the hydraulic pressure of the hydraulic pressure supply source P is supplied from the input port 8 and the discharge port 10 of the servo valve S to the spool valve. 21 is similar to the previous embodiment in that the pressure difference is eliminated from around the spool valve body 25. At this time, since the cut valves 42 and 43 are demagnetized, the normally closed type is used. The cut valve 42 prevents hydraulic pressure transmission from the output port 9 of the servo valve S to the free piston device 38, and the normally open cut valve 43 connects the wheel brake B to the master cylinder M.

When the master cylinder M is operated by depressing the brake pedal 1 for braking, the servo valve S and the switching valve 15 operate in the same manner as in the previous embodiment. The cut valves 42 and 43 are excited at the same time as the brake pedal 1 is depressed, and the former 42 is opened and the latter 43 is closed. Therefore, the hydraulic pressure output from the output port 9 of the servo valve S is reduced by the cut valve. 42 is transmitted to the free piston device first oil chamber 39 ₁ 38 via, to move the free piston 40 into the second hydraulic chamber 39 _2. This movement second hydraulic chamber 39 ₂ is boosted, the hydraulic pressure operates it is transmitted to the wheel brake B. At this time, the cut valve 43 in the closed state
Hydraulic transmission from the second oil chamber 39 ₂ to the master cylinder M side is prevented by the.

At the time of braking, if the hydraulic pressure 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 returns the normally open type cut valve 43 to the original position. The output hydraulic pressure of the master cylinder M can be directly transmitted to the wheel brake B via the cut valve 43.

FIG. 3 shows a third embodiment of the present invention.
The configuration is the same as that of the second embodiment except that a hydraulically responsive normally-open cut valve 44 is provided instead of the electromagnetic normally-closed cut valve 42 of the second embodiment.

The hydraulically responsive normally open type cut valve 44 is
The first oil chamber 39 of the piston device 38 ₁Valve chamber 4 connected to
5. The servo valve S formed on the bottom surface of the valve chamber 45
A valve seat 46 connected to the output port 9 and cooperating with the valve seat 46
Stem 47 that opens and closes the output port 9
A large-diameter pressure receiving piston 48 connected to the end, and the pressure receiving piston 48
Equipped with a cylinder hole 49 for slidably receiving the ston 48
You. The inside of this cylinder hole 49 is
It is partitioned into an upper hydraulic chamber 50 and a lower spring chamber 51.
The pressure chamber 50 is directly connected to the discharge port 10 of the servo valve S.
The spring chamber 51 is connected to the valve rod together with the pressure receiving piston 48.
The return spring 52 for urging the opening 47 in the opening direction is stored.
The cylinder hole 49 and the hydraulic chamber are inserted so that the valve stem 47 passes through.
In the through hole 53 provided between the holes 50, the outer peripheral surface of the valve rod 47 is formed.
The close sealing member 54 is mounted.

In FIG. 3, portions corresponding to those in the second embodiment are denoted by the same reference numerals.

When the switching valve 15 is excited when the brake pedal 1 is depressed, and the discharge port 10 of the servo valve S is opened to the reservoir 11 by this valve, the hydraulic chamber 50 of the cut valve 44 is simultaneously stored in the reservoir. Opened to 11.
Accordingly, the pressure receiving piston 48 moves upward with the resilience of the return spring 52 to pull up the valve rod 47, and the output port 9 of the servo valve S and the first oil chamber 3 of the free piston device 38.
Since between 9 ₁ to a conducting state, the free piston 40 as in the second embodiment, raised in response to the output hydraulic pressure from the output piston 9, the braking is performed.

When the brake pedal 1 is released, the switching valve 1
When the state 5 is changed to the demagnetized state, the discharge port 10 communicates with the hydraulic supply source P, so that the hydraulic pressure of the hydraulic supply source P is immediately transmitted to the hydraulic chamber 50 of the cut valve 44 that directly communicates with the discharge port 10. However, since the power is transmitted to the output port 9 while receiving the throttle resistance through the periphery of the spool valve body 25, the transmission to the output port 9 has a time delay. As a result, the pressure receiving piston 48 receives the oil pressure of the hydraulic chamber 50 on its upper surface, moves downward against the force of the return spring 52, and
Is seated on the valve seat 46 and the output port 9 is closed. Thereafter, even if the hydraulic pressure of the hydraulic pressure source P is transmitted to the output port 9 and presses the lower surface of the valve rod 47, the upper surface of the pressure receiving piston 48 has a larger pressure receiving area than the lower surface of the valve rod 47.
The closed state of the valve rod 47 is maintained by a downward pressing force obtained by multiplying the area difference by the oil pressure. Such a hydraulically responsive cut valve 44 has a simpler structure and is less expensive than an electromagnetic type cut valve 44, and does not use electric power, so that the load on the battery can be reduced.

Although the present invention has been described in connection with the case where the present invention is applied to a hydraulic braking device for an automobile, the present invention is also applicable to various hydraulic operating devices for industrial use. Further, the electric actuator in the present invention is not limited to the electric linear solenoid 22, and an electric motor or the like can be used.

[0038]

As described above, according to the present invention, between the discharge port of the spool valve and the hydraulic supply source and the reservoir, when the electric actuator is not operated, the discharge port and the hydraulic supply source communicate with each other. A switching valve is provided for communication between the discharge port and the reservoir during operation, and a cut valve is provided between the output port of the spool valve and the hydraulic actuator, which opens and closes according to the activation / deactivation of the electric actuator. When the electromagnetic actuator is not operated, the hydraulic pressure of the hydraulic supply source is filled in the closed spool valve, and the pressure difference can be removed from around the spool valve body, so that the closed state of the spool valve lasts for a long time. Even in this case, the locking phenomenon of the spool valve body can be avoided. At this time, transmission of hydraulic pressure from the output port of the spool valve to the hydraulic actuator is blocked by the cut valve, so that unnecessary operation of the hydraulic actuator can be prevented, and there is no inconvenience. Since the input port is always filled with the hydraulic pressure of the hydraulic supply source, if the spool valve is opened by the operation of the electric actuator, the hydraulic pressure can be immediately output from the output port, improving the responsiveness of the hydraulic actuator. Can be achieved.

[Brief description of the drawings]

FIG. 1 is an overall view of a main part of a hydraulic brake system for an automobile according to a first embodiment of the present invention, which is longitudinally sectioned.

FIG. 2 is an overall view of a main part of a hydraulic brake system for a vehicle according to a second embodiment of the present invention, which is longitudinally sectioned;

FIG. 3 is an overall view of a main part of a hydraulic brake system for an automobile according to a third embodiment of the present invention, which is longitudinally sectioned;

[Explanation of symbols]

 B Wheel brake (hydraulic actuator) S Servo valve 5 Cut valve 8 Input port 9 Output port 10 Drain port 11 Reservoir 15 Switching valve 21 Spool valve 22 Linear solenoid (electric actuator) 23 Housing 25 Spool valve body 38 Free piston device (Hydraulic actuator) ) 42 cut valve 44 cut valve

Claims (3)

(57) [Claims] An electric actuator for generating an actuation force according to an input, and a housing having an input port, an output port and a discharge port.
3) and slidably disposed in the housing (23), and cuts off between the input port (8) and the output port (9) by the operating force of the electric actuator (22), and the output port (9) and Operates from the valve-closed position communicating between the discharge ports (10) to the valve-opening position communicating between the input port (8) and the output port (9) by shutting off between the output port (9) and the discharge port (10). And a spool valve (21) provided with a spool valve element (25) to be used, constitutes a servo valve (S), and a hydraulic pressure source (P) is connected to the input port (8).
In addition, a hydraulic actuator (B,
38), the discharge port (10) is connected between the discharge port (10) and the hydraulic supply source (P) and the reservoir (11) when the electric actuator (22) is not operated. ) And a hydraulic supply source (P), and a switching valve (15) for communicating between a discharge port (10) and a reservoir (11) during operation thereof, and the output port (9) and a hydraulic actuator ( B, 38), there is provided a cut valve (5, 42, 44) that opens and closes according to the activation / deactivation of the electric actuator (22). Lock prevention device. 2. The device according to claim 1, wherein the cut valve (5, 42) is provided with an electric actuator (2).
A lock prevention device for a servo valve in a hydraulic operating device, which is a normally-closed electromagnetic valve that is excited at the time of operation 2). 3. The cut valve (44) according to claim 1, wherein the cut valve (44) is closed when receiving a hydraulic pressure of a hydraulic pressure supply source (P) into the discharge port (10). A lock prevention device for a servo valve in a hydraulic actuator, which is a hydraulically operated valve.