JP3069992B2 - Servo valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing having an electric actuator for generating a thrust in response to an input, an input port connected to a hydraulic supply source, and an output port connected to a hydraulic actuator, and a slidable housing. A spool valve provided with a spool valve body that is actuated by a thrust of an electric actuator from a valve closing position that shuts off between the input port and the output port to a valve opening position that communicates between the input port and the output port, The spool valve element is provided with a stopper member that abuts the stopper portion of the housing to restrict the valve closing position of the spool valve element, and urges the spool valve element in the valve closing direction by receiving the hydraulic pressure of the output port. The present invention relates to a servo valve provided with a series of reaction force pins.

[0002]

2. Description of the Related Art Such a servo valve is disclosed in, for example,
It is already known, as disclosed in JP-A-107369.

[0003]

In such a servo valve, the sliding resistance of the spool valve element has the largest initial dynamic resistance from the valve closing end point due to hydraulic lock or static friction, and sharply decreases when sliding starts. It's something small. For this reason, in the prior art, once the spool valve element starts moving from the valve closing end point by the operation of the electric actuator, the spool valve element slides excessively in the valve opening direction due to a sudden decrease in sliding resistance. A jumping phenomenon occurs in which the hydraulic pressure rises abruptly at the beginning of the output from the output port, as indicated by the p portion of line a shown in FIG.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses excessive sliding of a spool valve body even when the electric actuator is operated due to a sudden decrease in sliding resistance, thereby preventing a jumping phenomenon of output hydraulic pressure. It is an object of the present invention to provide the servo valve.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a valve closing stroke between a spool valve element and a stopper member which is smaller than a valve closing stroke from a valve closing end point to a valve opening start point of the spool valve element. While the axial play is provided, the stopper member is urged in the contact direction with the stopper portion with a large set load of the first return spring, and the spool valve body is biased with a small set load of the second return spring in the valve closing direction. The first feature is that the urging is performed with.

According to the present invention, in addition to the above features, the set load of the first return spring is slightly larger than the thrust of the electric actuator which can slide the spool valve body against the initial movement resistance at the end point of closing the valve. The setting is a second feature.

Further, in the present invention, in addition to the first or second feature, a third feature is that the set load of the second return spring is applied to the spool valve via a reaction force pin.

[0008]

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

First, the first embodiment of the present invention shown in FIG. 1 will be described. FIG. 1 is an overall view of a vehicle braking device to which the present invention is applied. In FIG. 1, a piston 3 of a master cylinder M is connected to a brake pedal 1 via a push rod 2.
Are connected. Output port 4 of the master cylinder M is connected to the first inlet ₆₁ of the electromagnetic switching valve 5, 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. In the demagnetized state, the electromagnetic switching valve 5
Communicating between inlet ₆₁ and outlet 7, and when it is excited between the second inlet 6 ₂ and the outlet 7 so as to communicate. Excited state of the solenoid 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 by accumulating the output hydraulic pressure of the master cylinder M to ensure a depression stroke of the brake pedal 1 Is connected between the output port 4 of the master cylinder M and the electromagnetic switching valve 5.

A hydraulic pressure source P is connected to the input port 8 of the servo valve S. The 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 pressure switch 14 for controlling the operation of the hydraulic pump 12. Then, the discharge port 10 of the servo valve S is opened to the reservoir 11.

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 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. When the control unit 18 receives a signal from the brake sensor 19 during normal times, the control unit 18 excites the electromagnetic switching valve 5. However, when the control unit 18 receives an output signal from the failure sensor 20 that detects a failure in the hydraulic supply source P and the servo valve S, Brake sensor 1
9 is invalidated.

The servo valve S is composed of a spool valve 21 and a linear solenoid 22 (electric actuator) connected to the spool valve 21. The spool valve 21 includes a housing 23, a valve cylinder 24 fitted to the housing 23, and a spool valve 25 fitted to the valve cylinder 24 so as to be able to move up and down. , An output port 9 and a discharge port 10 are provided.

The linear solenoid 22 includes a cylindrical outer yoke 28 connected to the housing 23, an end yoke 29 fixed to an upper end of the outer yoke 28,
A fixed core 30 fixed to the lower end of the outer yoke 28, a coil 31 disposed in the outer yoke 28,
The movable rod 32 is fitted to the end yoke 29 so as to be able to move up and down, and an operating rod 33 fixed to the movable core 32 and protruding from both upper and lower end surfaces thereof. It 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, this linear solenoid 22 is
, An electromagnetic force proportional to the electric current is generated between the fixed core 30 and the movable core 32,
To provide a downward thrust.

As shown in FIG. 2, in the spool valve 21, a guide member 38 slidably supports a small-diameter reaction force pin 37 abutting on the lower end of the spool valve body 25 at the lower end of the valve cylinder 24. Is fitted, and a spring chamber 39 in which the lower end of the spool valve body 25 faces is defined between the guide member 38 and the valve cylinder 24. An annular locking groove 40 is formed on the outer periphery of the lower end portion of the spool valve body 25, and an annular stopper member 42 that can abut on the upper end wall of the spring chamber 39, that is, the stopper portion 41, is provided in the locking groove 40 in a predetermined axial direction. It is attached with play g. Then, a first return spring 43 for urging the stopper member 42 toward the stopper portion 41 is accommodated in the spring chamber 39. The spring chamber 39 is provided in the passage 4 with the orifice of the spool valve body 25.
7 is connected to the discharge port 10.

The stopper member 42 is connected to the stopper 4
When the spool valve body 25 contacts the lower surface of the stopper member 42 in the locking groove 40, the ascending limit, that is, the valve closing end point is regulated. The spool valve element 25 maintains the valve-closed state while descending a predetermined valve-closing stroke L from the valve-closing end point, shuts off between the input port 8 and the output port 9 and outputs the output port 9 and the discharge port 1.
0, and after the above-mentioned valve-closing stroke L, the valve is in an open state, shutting off between the output port 9 and the discharge port 10 and communicating between the input port 8 and the output port 9. The communication opening between the input and output ports 8 and 9 is increased in accordance with the further lowering.

Here, the axial play g between the spool valve element 25 and the stopper member 42 is smaller than the valve closing stroke L of the spool valve element 25, that is, g <L.

The guide member 38 is provided with a reaction chamber 45 in which the lower end of the reaction pin 37 faces, and the reaction chamber 45 communicates with the output port 9. A retainer 46 is attached to the lower end of the reaction force pin 37, and a second return spring 44 that biases the reaction force pin 37 toward the spool valve body 25 via the retainer 46 is housed in the reaction force chamber 45.

Here, the set load of the first return spring 43 is set to be slightly larger than the thrust of the linear solenoid 22 which can slide the spool valve body 25 stopped at the valve closing end point against its initial dynamic resistance. And the second return spring 4
The set load of No. 4 is set much smaller than that of the first return spring 43.

Next, the operation of this embodiment will be described.

If the master cylinder M is not operating, the wheel brake B is connected to the oil chamber of the master cylinder M by the electromagnetic switching valve 5, so that the oil chamber of the wheel brake B is opened to the reservoir of the master cylinder M. Have been.

On the other hand, in the servo valve S, since the linear solenoid 22 is demagnetized, the spool valve element 25 of the spool valve 21 is held at the valve closing end with a weak set load of the second return spring 44, as described above. Between the input and output ports 8 and 9, the output port 9 and the discharge port 1
Communication is made between 0.

Here, when the master cylinder M is operated by depressing the brake pedal 1 to perform braking, the control unit 18 first receives the signal from the brake sensor 19, switches the electromagnetic switching valve 5, and switches the master cylinder M. M and the wheel brake B are cut off, and the output port 9 of the servo valve S and the wheel brake B are connected. Subsequently, since the control unit 18 excites the linear solenoid 22 of the servo valve S with an electric quantity according to the signal from the pedaling force sensor 17, the operating rod 33 causes the spool valve body 25 of the spool valve 21 to have a thrust corresponding to the pedaling force. Press down.

By the way, as described above, the spool valve 25
Is relatively large, but since the set load of the second return spring 44 that urges the valve body 25 to the valve closing end point is extremely small, the resistance due to the set load is small.

When the thrust generated by the linear solenoid 22 exceeds the initial motion resistance of the spool valve element 25 and the spool valve element 25 starts to descend, the descending speed increases due to a sudden decrease in the sliding resistance. By setting g <L, the spool valve body 25 comes into contact with the stopper member 42 immediately before reaching the valve opening start point, and the descending force of the spool valve body 25 causes the first load having a large set load.
Absorbed by the return spring 43, excessive lowering is suppressed. In this way, the jumping of the output hydraulic pressure due to the rapid opening of the spool valve element 25 is avoided.

Thereafter, the spool valve element 25 compresses the first return spring 43 in response to the increase of the thrust of the linear solenoid 22 and gently descends to open the valve, and shuts off between the output port 9 and the discharge port 10. At the same time, since the communication between the input port 8 and the output port 9 is established, as shown by the line b in FIG.
The hydraulic pressure of the hydraulic pressure source P is output from the output port 9 according to the opening between the input and output ports 8 and 9 and transmitted to the wheel brake B to operate it. At the same time, the output oil pressure of the output port 9 is also transmitted to the reaction force chamber 45 to give an upward thrust to the reaction force pin 37 and act on the spool valve body 25. The downward thrust, the upward thrust of the reaction force pin 37 and the double return spring 4
3, 44 are displaced so as to be balanced with the sum of the upward repulsive forces, whereby the oil pressure at the output port 9, ie, the braking force by the wheel brake B, corresponds to the thrust of the linear solenoid 22, ie, the pedaling force on the brake pedal 1. It will be.

Next, when the pedaling force is released from the brake pedal 1, the control unit 18 returns the electromagnetic switching valve 5 to the original position and returns the servo valve S to the initial closed state.
Since the output port 9 is opened to the reservoir 11 via the discharge port 10, the wheel brake B is in a non-operating state.

When the hydraulic pressure source P and the servo valve S are out of order, the control unit 18 can operate the fault sensor 2 even during braking.
Since the electromagnetic switching valve 5 is kept at the original position in response to the signal from 0, the output hydraulic pressure of the master cylinder M can be directly transmitted to the wheel brake B via the electromagnetic switching valve 5. Therefore, fail safe is ensured.

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 according to the present invention is not limited to the linear solenoid, but may be an electric motor or the like.

[0030]

As described above, according to the first aspect of the present invention, the shaft between the spool valve body and the stopper member, which is smaller than the valve closing stroke from the closing end point of the spool valve body to the valve opening start point. While providing directional play, the stopper member is urged in the contact direction with the stopper portion with a large set load of the first return spring, and the spool valve body is biased with a small set load of the second return spring in the valve closing direction. When the spool valve body starts sliding due to the operation of the electric actuator, the spool valve body is received by the first return spring having a large set load immediately before the valve is opened, and the spool valve is suddenly reduced due to a sudden decrease in sliding resistance. Excessive sliding of the valve body can be suppressed, and a jumping phenomenon of the output hydraulic pressure can be prevented.

According to the second feature of the present invention, the set load of the first return spring is made slightly smaller than the thrust of the electric actuator which can slide against the initial movement resistance at the end point of closing the spool valve body. Because the spool valve is set to a large value, after suppressing excessive sliding of the spool valve, the spool valve can be immediately actuated by the continuously increasing thrust of the electric actuator, so that a hydraulic pressure corresponding to the thrust is output from the output port without delay. can do.

Further, according to a third feature of the present invention, the second
Since the set load of the return spring is applied to the spool valve body via the reaction force pin, the reaction force pin is held at the contact position with the spool valve body by the force of the second return spring, and the reaction force by the output hydraulic pressure is maintained. Can always be accurately given to the spool valve element.

[Brief description of the drawings]

FIG. 1 is an overall view of a vehicle braking device according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of a spool valve portion of the servo valve in FIG.

FIG. 3 is a graph of electric quantity-output hydraulic characteristics of a servo valve, in which a line a shows a conventional one and a line b shows one according to the present invention.

[Explanation of symbols]

 g Axial play B Wheel brake (hydraulic actuator) L Valve closing stroke P Hydraulic supply S Servo valve 8 Input port 9 Output port 10 Drain port 21 Spool valve 22 Linear solenoid (electric actuator) 23 Housing 25 Spool valve body 37 Reaction force Pin 41 Stopper part 42 Stopper member 43 First return spring 44 Second return spring

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16K 31/00-31/11 F16K 3/00-3/36

Claims (3)

(57) [Claims] A housing having an electric actuator (22) for generating a thrust according to an input, an input port (8) connected to a hydraulic supply source (P), and an output port (9) connected to a hydraulic actuator (B). (23), and slidably disposed in the housing (23). The thrust of the electric actuator (22) cuts off the input port (8) and the output port (9) from the valve closing position to the input port ( 8) and a spool valve (21) having a spool valve element (25) that is operated to an open position communicating with the output port (9). The spool valve element (25) is provided with a housing (23). ), A stopper member (42) for abutting against the stopper portion (41) to regulate the valve closing position of the spool valve element (25) is provided, and the spool valve element receives the hydraulic pressure of the output port (9). In a servo valve provided with a reaction force pin (37) for urging the valve (25) in the valve closing direction, a servo valve is provided between the spool valve body (25) and the stopper member (42).
An axial play (g) smaller than the valve closing stroke (L) from the valve closing end point to the valve opening start point of the spool valve body (25) is provided, and the stopper member (42) is connected to the stopper portion (4).
The first return spring (43) is urged in the contact direction with 1) with a large set load, and the spool valve body (25) is pressed in the valve closing direction with a small set load of the second return spring (44). A servo valve characterized by being energized. 2. An electric actuator (1) according to claim 1, wherein the set load of the first return spring (43) can slide the spool valve body (25) against initial movement resistance at the closing end point. 22) A servo valve characterized in that the thrust is set slightly larger than the thrust described in 22). 3. The device according to claim 1, wherein the set load of the second return spring (44) is changed by a reaction force pin (37).
A servo valve characterized by acting on a spool valve body (25) via a valve.