JPH0435380B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an actuator for adjusting brake fluid pressure in an anti-skid device for an automobile.

(B) Prior Art An antiskid device for an automobile is a device that prevents the rear wheels from locking during sudden braking and prevents the vehicle from spinning due to sideways skidding, and has been known for a long time.

As an actuator for regulating brake fluid pressure in such an anti-skid device, there is a brake fluid pressure regulating valve that causes brake fluid pressure and control fluid pressure to act respectively on both pressure receiving surfaces of a piston housed in the actuator body, and that the brake fluid pressure side follows the piston. In addition, a solenoid valve operated by the anti-skid controller is provided on the control fluid pressure side, and the solenoid valve is opened in response to the anti-skid signal to reduce the control fluid pressure and return the piston to the brake fluid. A basic configuration in which a pressure regulating valve is closed is known.

(c) Problem to be solved by the invention The control fluid pressure acting on one pressure receiving surface of the piston is reduced when the anti-skid signal is issued from the controller as described above, and as a result, the brake fluid pressure regulating valve is closed. However, if an anti-skid device with such a function is provided, there is a risk that the brakes will become ineffective due to a failure in the control hydraulic system. Therefore, it is necessary to provide a so-called fail-safe function so that when a failure occurs in the control hydraulic system, the anti-skid function is immediately lost and normal braking function is maintained.

An object of the present invention is to provide an actuator incorporating a fail-safe function as described above.

(d) Means for Solving the Problems In order to achieve the above object, the present invention provides a stopper on the wall surface of the control hydraulic pressure chamber so that it can move in and out, and normalizes the pressing force that urges the stopper in the projecting direction. The piston is provided with an engaging part for the stopper, and the position of the stopper is adjusted such that the piston engages the engaging part when the brake fluid pressure regulating valve is open. The structure is selected to be in a position where it can be obtained.

(e) Embodiments Examples of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the actuator body 1 includes an input port 3 and an output port 4 connected to the brake hydraulic pressure passage 2, and an input port 6 and an output port 7 connected to the anti-skid control hydraulic pressure passage 5.
are formed, and each of these ports communicates with a cylinder bore 8 provided in the main body 1.

One end of the cylinder bore 8 is closed by a plug 9, and a valve hole 10 is formed by narrowing the bore 8.
An input hydraulic pressure chamber 11 for brake hydraulic pressure is formed between the input port 4 and the plug 9, and the input port 4 is communicated with the hydraulic pressure chamber 11. A ball valve 12 provided as a brake fluid pressure regulating valve is inserted into the hydraulic pressure chamber 11, and a spring 13 that biases the ball valve 12 toward the valve hole 10 is interposed between the ball valve 12 and the plug 9. ing.

The portions of the bore 8 that communicate with the valve hole 10 are, in order from the right, a small diameter portion 14, a medium diameter portion 15, and a large diameter portion 16.
are formed through the first stage part 17 and the second stage part 18, respectively, and a piston 22 which also has a small diameter part 19, a medium diameter part 20 and a large diameter part 21 is formed so as to fit into these parts 14, 15, 16. It is slidably inserted into the bore 8.

The output port 3 is communicated with the small diameter portion 14 of the bore 8 at a position where it is not blocked by the piston 22 in the illustrated state where the piston 22 has moved forward to the right as much as possible. Small diameter part 19
The cup seal 23 fitted on the outer periphery of the valve hole 10
An output hydraulic pressure chamber 24 is formed between the two. Further, a valve rod 25 is protruded from the tip of the small diameter portion 19 of the piston 22, and comes into contact with the ball valve 12 as shown in the figure when the piston 22 is at its forward limit, thereby opening the valve hole 10.

A communication portion 26 that is thinner than the medium diameter portion 20 is formed between the medium diameter portion 20 and the large diameter portion 21 of the piston 22 . A cup seal 27 is fitted on the outer periphery of the medium diameter portion 20, and the input port 6 is communicated with a bore portion on the outer periphery of the communicating portion 26 to form an input hydraulic pressure chamber 28.

A communication hole 29 is formed in the communication portion 26,
An orifice 30 communicating with the communication hole 29 is formed at the center of the piston large diameter section 21, a valve chamber 31 protruding from the large diameter section 21 is formed around the orifice 30, and a ball valve 32 is accommodated in this. There is.

The large diameter portion 16 of the bore 8 is closed by a plug 33, and an output hydraulic pressure chamber 34 is formed between the plug 33 and the piston large diameter portion 21, and the output port 7 is communicated with this hydraulic pressure chamber 34. ing. Inside the output hydraulic pressure chamber 34 are a balance spring 35 interposed between the plug 33 and the piston large diameter portion 21, and a plug 3.
A spring 36 is inserted between the ball valve 32 and the ball valve 32.

Further, a solenoid valve 37 is interposed in the output port 7 to close the port 5 in a normal state.

Further, a stopper 38 is provided in a portion of the main body 1 in the bore medium diameter portion 15 so as to protrude and retract with respect to the input hydraulic pressure chamber 28 . The stopper 38 is fluid-tightly inserted into a small bore 39 in a direction perpendicular to the bore 8, and a spring 41 is interposed between a support plate 40 fitted in the small bore 39, thereby pushing the stopper 38 in the projecting direction. It is energizing. However, since the spring force of the spring 41 is set to be smaller than the hydraulic pressure in the input hydraulic pressure chamber 28, as long as the normal control hydraulic pressure is acting on the input hydraulic pressure chamber 28, as shown in the figure, In the immersion state, the piston 22
does not impede movement. The above-mentioned stopper 38 is provided at the position where the piston 2 is at the forward limit as shown in the figure.
2 engagement step portion 42, that is, the medium diameter portion 20 and the communication portion 26
The periphery of the small bore 39 almost coincides with the step between
It is selected so that when the stopper 38 protrudes from this state, the stopper 38 engages with the engagement step 42 with the amount of retraction of the piston 22 being substantially zero.

Note that an air vent hole 4 is provided in the first step 17 of the bore 8.
3 and a filter 44 are provided.

The actuators described above are connected as described below and constitute a part of the anti-skid device.

A master cylinder 45 is connected to the input port 4 on the brake fluid pressure side of the actuator via the brake fluid pressure passage 2, and the brake 4 of the rear wheel 46 is connected to the output port 3 via the brake fluid pressure passage 2.
7 is connected. A rotation sensor 48 is provided on the rear wheel 46, and its output signal is input to an electronic controller (computer) 49. The controller 49 processes the above signals and detects whether the rear wheels 46 are locked or not.
An anti-skid signal is output to the electromagnetic mail 37.

On the other hand, an accumulator 50 is connected to the input port 6 on the anti-skid control hydraulic pressure side via a control hydraulic pressure passage 5, and the accumulator 50 is connected to a liquid tank 52 via a pressure reducing pump 51. Further, the output port 7 is connected to the tank 52 through the solenoid valve 37 and the control hydraulic pressure passage 5.

Next, the operation of the actuator will be explained.

[During non-braking and normal braking] (Fig. 1) Since the solenoid valve 37 is closed during non-braking, the control hydraulic pressure from the accumulator 50 acts equally on the input hydraulic pressure chamber 28 and the output hydraulic chamber 34. , the piston 22 is moved to its forward limit state where its stepped portion abuts the first stepped portion 17 of the bore 8 as shown in FIG.
5 to push the ball valve 12 and open the valve hole 10.

In this case, the ball valve 32 on the control hydraulic pressure side closes the orifice 30 by the spring force of the spring 36, and the stopper 38 is retracted by the control pressure of the input hydraulic pressure chamber 28.

In the above configuration, when the brake pedal 53 is depressed and hydraulic pressure is generated from the master cylinder 45, the hydraulic pressure acts on the brake 47 through the valve hole 10, and normal braking is performed.

[Anti-skid control] (Fig. 1, Fig. 2, Fig. 3)
(Figure) When the rotational speed of the rear wheels 46 rapidly decreases due to sudden braking, and the rotation sensor 48 detects a locked state or a state close to it, the controller 4
An anti-skid signal is output from 9, and the solenoid valve 3
Open 7.

When the control hydraulic pressure in the output hydraulic pressure chamber 34 suddenly decreases due to the opening of the solenoid valve 37, the balance of the pressures acting on the piston 22 (mainly the control hydraulic pressure, the brake hydraulic pressure, and the spring force of the balance spring 35) changes. A change occurs, compressing the balance spring 35 and moving the piston 22 to the left. the result,
On the brake fluid pressure side, from the valve hole 10 to the valve stem 2
5 comes out, and the ball valve 12 closes the valve hole 10 by the spring force of the spring 13, cutting off the brake fluid pressure transmitted from the master cylinder 45 to the brake 47. Then, when the piston 22 moves further to the left, the volume of the output hydraulic pressure chamber 24 increases, so that the brake hydraulic pressure is reduced and the brake 47 is released.

In the above case, the ball valve 32 on the control hydraulic pressure side is in a state in which the orifice 30 is opened because the pressure in the input hydraulic pressure chamber 28 is higher than the pressure in the output hydraulic pressure chamber 34. (FIG. 2) When the rear wheel 46 is released from a locked or nearly locked state by releasing the brake 47, the controller 49 detects this state through the rotation sensor 48, and resets the solenoid valve 37 by canceling the brake lock signal. Then, close the output port 7 again (FIG. 3). As a result, the output hydraulic pressure chamber 3
4 increases, the balance of pressure acting on the piston 22 is disrupted, causing it to move to the right.

As the piston 22 moves, the hydraulic pressure in the output hydraulic pressure chamber 24 on the brake hydraulic pressure side increases, so the brake hydraulic pressure acting on the brake 47 is increased, and the rear wheel 46 becomes locked or close to lock again. An anti-lock signal is output as shown below, and the brake is released.

By repeating this action two or three times, skidding of the wheels is prevented.

[At the time of failure of control hydraulic pressure] (Figures 1 and 4) If a failure occurs in the control hydraulic system due to a failure of the hydraulic pump 51 in the state shown in Figure 1, the pressure in the input hydraulic pressure chamber 28 will decrease. Then, the stopper 38 protrudes by the force of the spring 41 and engages with the engagement step 42 of the piston 22. Therefore, since the piston 22 cannot move to the left, the valve hole 10 on the brake fluid pressure side is held open.

Therefore, although the anti-skid function is lost, the normal braking function is ensured, resulting in what is called a fail-safe.

In order to ensure the above function, it is most desirable that the stopper 38 engages the piston 22 when the piston 22 is fully advanced, that is, when the ball valve 12 is fully opened. If the ball valve 12 is opened by a predetermined amount, the position of the small bore 39 may be set so that the piston 22 engages with the stopper 38 at a slightly retracted position.

(G) Other Embodiments In the above embodiment, the ball valve 32 is provided in the orifice 30, and when the solenoid valve 37 is opened, a large pressure difference between the input hydraulic pressure chamber 28 and the output hydraulic pressure chamber 34 is maintained, and the piston 22 However, if the required pressure difference can be obtained only with the orifice 30, the ball valve 32 may be omitted.

(f) Effects As described above, in this invention, the stopper applies the required pressing force to the control hydraulic pressure chamber, is provided at the required position, and engages with the piston, thereby preventing failure of the control hydraulic system in the actuator. This has the effect of detecting a brake failure, quickly and safely disabling the anti-lock control function, and ensuring normal braking function.

[Brief explanation of drawings]

FIG. 1 is a sectional view, and FIGS. 2 to 4 are diagrams for explaining the order of operation. 1...actuator body, 3...input port, 4...output port, 6...input port, 7...
...Output port, 8...Bore, 10...Valve hole, 11
...Input hydraulic pressure chamber, 12...Ball valve, 19...Small diameter section, 20...Medium diameter section, 21...Large diameter section, 22...
... Piston, 24 ... Output hydraulic pressure chamber, 25 ... Valve stem, 28 ... Input hydraulic pressure chamber, 30 ... Orifice,
32... Ball valve, 34... Output hydraulic chamber, 35...
...Balance spring, 37... Solenoid valve, 38...
…stopper.

Claims (1)

[Scope of Claims] 1. Brake fluid pressure and control fluid pressure are applied to both pressure receiving surfaces of a piston housed in the actuator body, respectively, and a brake fluid pressure regulating valve that follows the piston is provided on the brake fluid pressure side, and a brake fluid pressure regulating valve that follows the piston is provided on the control fluid pressure side. An anti-skid actuator is provided with a solenoid valve driven by an anti-skid controller, and opens the solenoid valve in response to an anti-skid signal to reduce the control hydraulic pressure and return the piston. A stopper is provided in a small bore provided on the wall of the output hydraulic pressure chamber in a liquid-tight manner so as to be able to freely protrude and retract, and the pressing force that biases the stopper in the protrusion direction is set to be smaller than the control hydraulic pressure in normal conditions, and the above-mentioned pressure is applied to the piston. An anti-skid device, characterized in that an engagement step is provided for the stopper, and the stopper is positioned at a position where the piston can engage with the engagement step when the brake fluid pressure regulating valve is open. Actuator. 2. According to claim 1, the position of the stopper is selected so that the piston can engage with the engagement step when the brake fluid pressure regulating valve is opened to the maximum extent. Anti-skid actuator as described.