JPS6154621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative pressure booster used in a hydraulic brake system of an automobile.

A hydraulic brake system for an automobile operates a master cylinder by a driver's force on a brake pedal, and supplies the generated master cylinder hydraulic pressure to the wheel cylinders of each wheel to simultaneously brake all wheels. However, there is a limit to the amount of force a driver can apply to the brake pedal, and the master cylinder hydraulic pressure corresponding to this amount of force cannot be sufficient to reliably brake a large vehicle. Therefore, a negative pressure booster (usually referred to as a master back) that vacuum boosts the brake pedal depression force and inputs the vacuum booster to the master cylinder is used in a typical hydraulic brake device.

As this type of booster, for example,
The one shown in Figure 1 published in Publication No. 91756 is known. That is, a negative pressure chamber 2 and a variable pressure chamber 3 are provided on both sides of the power piston 1, and when the valve operating rod 4 is pressed in conjunction with the depression of the brake pedal, a vacuum valve 5 that closes in response to the pressing of the valve operating rod 4 operates to supply pressure to the variable pressure chamber 3. Air valve 6 that cuts off the negative pressure supply and then opens
Atmospheric pressure is switched and introduced into the variable pressure chamber 3, and the power piston 1 is actuated by the pressure difference between the two chambers 2 and 3, and a boosted output is obtained via the push rod 7. It is known that a plunger 8 and a push rod 7 are brought into contact with each other via a reaction disk 9 made of an elastic material, so that the driver can feel the reaction force of pressing the brake pedal.

However, this one is vacuum valve 5
consists of a valve seat 10 formed on the power piston 1 and a valve body 11 that responds to the valve plunger 8. When the brake pedal is released, negative pressure is transferred from the negative pressure chamber 2 to the variable pressure chamber 3. At the time of introduction, the opening stroke of the vacuum valve 5 is the same as its closing stroke, and the master cylinder hydraulic pressure relative to the brake pedal depression force (reaction force) F is determined.
The changes in Pm are shown in Figure 2. In other words, when the brake pedal is released, the master cylinder fluid pressure (braking force) is only held at a constant value for a short time due to a mechanical delay, and there is not much change in master cylinder fluid pressure between when the brake pedal is pressed and when it is released. Ta. Therefore, this may give the driver a feeling that the braking force is insufficient when the brake pedal is released, and it is desired that a high braking force be maintained for a predetermined period of time even if the force applied to the brake pedal is reduced. Ta.

This invention was made in response to such a request, and includes a protruding swinging member that swings due to the differential pressure between the negative pressure chamber and the variable pressure chamber on either the valve seat or the valve body constituting the vacuum valve. It is an attempt to meet the above demand by making the opening stroke of the vacuum valve larger than the closing stroke, that is, by making the time during which the vacuum valve is opened longer than its closing time.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

3 and 4 show the structure of an embodiment of the negative pressure booster according to the present invention, and the case where this is used in a hydraulic brake system for an automobile will be described below. In the figure, 21 indicates a front shell, and 22 indicates a rear shell, and these shells 21 and 22 are combined to form a main body 23 of the booster of the present invention. A power piston 24 and a diaphragm 25 are housed within the main body 23, and the cylindrical protrusion 24a of the power piston 24 is slidably supported within the center opening of the rear shell 22 by a bearing/seal member 26. diaphragm 25
Its outer peripheral edge is clamped to the combined portion of the shells 21 and 22, and its inner peripheral edge is fitted to the power piston 24, thereby defining a negative pressure chamber 27 and a variable pressure chamber 28 on both sides of the power piston 24, respectively. Negative pressure chamber 27 is constantly guided with, for example, engine intake manifold negative pressure through connector 29 and maintained at a negative pressure, and variable pressure chamber 28 is supplied with negative pressure in negative pressure chamber 27 or through an air valve via a vacuum valve as described later. Deriving atmospheric pressure.

A cylindrical flexible valve body 30 is provided within the cylindrical protrusion 24a of the power piston 24, and one end of the valve body 30 is sealed within the cylindrical protrusion 24a. Note that the other end of the flexible valve body 30 has an outer peripheral surface protruding. 31
is a valve seat that comes into contact with the valve body 30 at the shoulder of the cylindrical protrusion 24a, and this valve seat 31 has a protruding swinging member 32 with an inner circumferential surface of a tip of a deformable elastic body protruding.
is attached. The other end of the valve body 30 is made to face the valve seat 31 of the cylindrical protrusion 24a, and is movable toward or away from the protruding rocking member 32 of the valve seat 31 by deformation of the valve body 30 itself. There is. The valve seat 31 and the valve body 30 constitute a vacuum valve 33 as a whole. Cylindrical protrusion 2
An air filter 34 is provided at the open end of the shell 22, and a dust boot 35 enclosing the cylindrical protrusion 24a is provided between the air filter 34 and the opening of the shell 22 to protect the bearing/seal member 26 from dust.
A valve operating rod 36 is provided to slidably pass through the air filter 34, and a valve plunger 37 is partially pushed into the spherical inner end of the rod 36 to be integrally connected. Two springs 38 and 39 act on the valve operating rod 36, one spring 38 is supported by the fixed end of the valve body 30 and serves as a return spring for the valve operating rod 36, and the other spring 39 is It is supported by the movable portion of the valve body 30 and used to urge the movable end of the valve body 30 toward the valve plunger 37.
In this way, the end face of the movable end of the valve body 30 is normally seated on the opposite end face of the valve plunger 37, and the air valve 40 constituted by these is maintained in the closed position.

The valve plunger 37 is fitted into the bottom of the cylindrical protrusion 24a so as to be slidable in the axial direction.
The axial movement of the piston 7 is limited within a predetermined range by a stop key 41 inserted in the power piston 24.

On the surface of the power piston 24 facing the negative pressure chamber 27,
Coaxially connected to the fitting hole of the valve plunger 37,
A hole having a larger diameter than this is formed, and a reaction disk 42 made of an elastic material is fitted into this hole, and an enlarged portion of a push rod 43 is fitted and fixed therein. The push rod 43 penetrates the negative pressure chamber 27 and protrudes from the shell 21 under liquid-tight sealing by the seal 44, and connects the shell 21 and the power piston 24.
A return spring 45 for the power piston 24 is compressed between.

The power piston 24 is formed with a port 46 that opens from the negative pressure chamber 27 into the cylindrical protrusion 24a near the valve seat 31, and a port 47 that extends from the fitting hole of the valve plunger 37 to the variable pressure chamber 28. ,
These ports 46 and 47 are used as load passages or atmospheric pressure passages during operation, which will be described later.

The load type booster of the present invention configured as described above has the following features:
The master cylinder 50 is attached to the vehicle body by bolts 48 implanted in the shell 22, and the master cylinder 50 is attached to the main body 23 by bolts 49 implanted in the shell 21, and the tip of the push rod 43 is abutted against the piston of the master cylinder 50. By connecting a brake pedal (not shown) to the tip of the English rod 36 through a clevis 51, it can be used in a hydraulic brake system, and functions as follows.

That is, FIG. 3 shows a non-operating state in which the brake pedal is not depressed. At this time, the valve operating rod 36 is set to the maximum protruding position by the spring 38, so that the valve plunger 37 integrated with the valve operating rod 36 is moved. While the air valve 40 constituted by the valve body 30 is kept closed, the movable end of the valve body 30 (the left end in the figure) is moved against the spring 39 to cause the valve seat 31 to protrude and swing due to the deformation of the valve body 30. A vacuum valve 33 constituted by these members is opened and spaced apart from the member 32. Therefore, the negative pressure in the negative pressure chamber 27 is guided to the variable pressure chamber 28 through the port 46, the gap between the protruding swinging member 32 of the valve seat 31 and the valve body 30 (the opening degree of the vacuum valve 33), and the port 47. Since the chambers 27 and 28 are at the same pressure, the power piston 24
is maintained at the rightmost position shown in the figure by a return spring 45.

Here, when the brake pedal is depressed, the valve operating rod 36
When pushed in the direction of arrow A against the spring 38,
The movable end of the valve body 30 and the valve plunger 37 are brought into contact with each other by the spring 39 (the air valve 40
The valve operating rod 36 moves to the left in FIG. 3 while keeping the valve operating rod 36 in the closed state. During this leftward movement, when the movable end of the valve body 30 is seated on the protruding swinging member 32 of the valve seat 31, the vacuum valve 33 composed of these is closed and the negative pressure supply to the variable pressure chamber 28 is cut off. After the vacuum valve 33 closes,
When the brake pedal is further depressed, the movable end of the valve body 30 cannot move further to the left, so the vacuum valve 33 remains closed, and the valve operating rod 36 moves further to the left to move the valve plunger 37 toward the valve body 30. In this way, the air valve 40 constituted by these is opened in the variable pressure chamber 28 from the air filter 34 to the inside of the cylindrical protrusion 24a and the gap between the valve body 30 and the valve plunger 37 (the air valve 40 (opening degree), atmospheric pressure is switched and introduced through the port 47, and this introduction of atmospheric pressure causes a negative pressure drop in the variable pressure chamber 28. As a result, the power piston 24
A pressure difference is generated on both sides of the cylinder, and the power piston 24 moves to the left against the return spring 45 due to the pressure difference, applying force to the push rod 43, which in turn operates the master cylinder 50 under vacuum boost. be able to.

When the master cylinder 50 is operated, a reaction force is generated in the piston due to the hydraulic pressure, and this reaction force is transmitted to the enlarged portion of the push rod 43, thereby compressing the reaction disk 42. The reaction disk 42 acts like a liquid, transmitting the reaction force input from the enlarged part of the push rod 43 to the power piston 24 and the valve plunger 37, allowing the driver to press the brake pedal via the valve operating rod 36. You can feel the reaction force when you step in.

Due to the left movement of the power piston 24, the power piston 24, the movable end of the valve body 30, and the valve plunger 37 are again in relative positions, and both valves 3
3 and 40 are both closed, and the driving force of the power piston 24 due to the differential pressure and the reaction force of pressing the brake pedal are balanced with the spring force of the return spring 45 and the reaction force brought about by the piston of the master cylinder 50. The power piston 24 then stops at a position corresponding to the amount of depression of the brake pedal.

When the amount of depression of the brake pedal is increased, the power piston 24 moves further to the left according to the amount of depression due to the repetition of the above-described action, and the push rod 4
3, the force pushing the master cylinder 50 can be increased, and the master cylinder 50 can be operated under successive vacuum boosts.

Next, the case where the brake pedal is released will be explained. In this case, by first releasing the brake pedal, the balance between the aforementioned driving force, spring force, and reaction force is disrupted, and the valve plunger 37 moves to the right in FIG. As a result, the valve plunger 37 comes into contact with the valve body 30 and closes the air valve 40. Next, when the valve plunger 37 moves further to the right, the movable end of the valve body 30 gradually separates from the protruding swinging member 32 of the valve seat 31. That is, while the inside of the variable pressure chamber 28 is maintained at atmospheric pressure, the negative pressure chamber 27 and the port 46 side are at negative pressure. As shown, the tip swings outward while contacting the valve body 30, and separates from the valve body 30 with a delay from the time of depression. As a result, the vacuum valve 33 is opened, and as shown in FIG. 7, the opening stroke of the vacuum valve 33 becomes large. When the negative pressure chamber 27 and the variable pressure chamber 28 are both maintained at negative pressure by closing the air valve 40 and opening the vacuum valve 33, the power piston 24 moves to the right by the return spring 45, and returns to the third position.
Return to the state shown in the figure.

In addition, in the above-mentioned embodiment, the swinging member 32 protrudes from the valve seat 31 constituting the vacuum valve 33.
the valve body 3 so as to face this protruding swinging member 32.
Although the movable end portion of 0 is provided so as to be deformable, in the present invention, the protruding swinging member 32 may be provided on either the valve seat 31 or the valve body 30. That is,
A protruding swinging member 32 made of an elastic body is provided on the valve seat 31 in FIG. 5, and is provided integrally with the valve body 30 in FIG. The operation in this case is similar to the previous embodiment.

As described above, according to the present invention, a protruding swinging member made of an elastic body is provided on either the valve seat or the valve body constituting the vacuum valve, which closes the gap between the valve seat and the valve body by means of a pressure difference. Even if the pedal is released, the braking force is maintained for a predetermined period of time, giving the driver a sense of satisfaction.

[Brief explanation of the drawing]

Figure 1 is a longitudinal side view showing a conventional negative pressure booster, Figure 2 is a diagram showing the relationship between brake pedal depression reaction force and master cylinder hydraulic pressure due to the conventional negative pressure booster, Fig. 3 is a vertical sectional side view showing one embodiment of the negative pressure booster according to the present invention, Fig. 4 is an enlarged view of section B in Fig. 3, and Figs. 5 and 6 show other embodiments of the present invention. FIG. 7 is an enlarged view similar to FIG. 4 shown in FIG. 4, and FIG. 7 is a diagram showing the relationship between the depression reaction force of the brake pedal and the master cylinder hydraulic pressure by the negative pressure booster according to the present invention. 24...Power piston, 27...Negative pressure chamber, 2
8... Pressure transformation chamber, 36... Valve operating rod, 37... Valve plunger, 30... Valve body, 31... Valve seat, 33... Vacuum valve,
40...Air valve, 43...Push rod,
42... Reaction disk, 32... Protruding rocking member.

Claims (1)

[Claims] 1 A negative pressure chamber and a pressure changing chamber are provided on both sides of the power piston, and when the valve plunger is pushed in by the valve operating rod, the pressure is changed by a vacuum valve that closes when the valve body responding to the valve plunger comes into contact with the valve seat of the power piston. While cutting off the negative pressure supply to the chamber, atmospheric pressure is switched and introduced into the variable pressure chamber by an air valve that is subsequently opened, so that an output is obtained from the power piston via a push rod, and the valve plunger and the push rod are made of an elastic material. In a negative pressure booster that obtains a reaction force by abutting against each other through a manufactured reaction disk, a valve body or a valve seat of a power piston constituting the vacuum valve is used to close the space between these valve seats and the valve body. 1. A negative pressure booster comprising a protruding swinging member made of an elastic body.