JPH0141539B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake booster, and more particularly to a brake booster in which a master cylinder is disposed on the rear side of a booster mechanism including a power piston, that is, on the brake pedal side.

As this type of brake booster, one is known in which a valve mechanism for switching a fluid circuit and a reaction disk as a reaction force transmission mechanism are disposed in a valve body of a power piston shaft. When a valve mechanism and a reaction disk are provided in the valve body of the power piston shaft, an input shaft that interlocks with the valve mechanism and an output that interlocks the power piston and the piston of the master cylinder via the reaction disk. It is necessary to arrange the end face formed on the power piston or valve body and the end face formed on the input shaft in the rear end face of the reaction disc, and the end face formed on the output shaft as the rear end face of the reaction disk. It is necessary to configure the reaction force transmission mechanism by arranging the front side end faces of the front disks to face each other.

For this reason, conventionally, a cylindrical input shaft is slidably provided on the outer periphery of the output shaft, and its tip surface is opposed to the rear end surface of the reaction disk, and on the other hand, a head is formed at the tip of the output shaft. Its rear end face faces the tip face of the reaction disk, and a protrusion protruding in the radial direction is formed on the rear end of the output shaft, and this protrusion is slidably passed through the slit formed in the cylindrical input shaft. There is one in which the piston protrudes outward and its tip is linked to the piston of the master cylinder. However, since a large boosted output is applied to the output shaft, and the radial protrusion is designed to be disadvantageous in terms of strength, sufficient wall thickness is required to ensure the strength of that part. As a result, the master cylinder has also become larger and heavier.

In view of these points, the present invention is designed to allow the piston of the master cylinder to be directly mounted on the output shaft by slidably disposing the output shaft on the outer periphery of the input shaft, thereby reducing the acting force. The weight is reduced by making the structure related to the large output shaft superior in strength.

The present invention will be described below with reference to the illustrated embodiments.
In FIG. 1, 1 is a shell consisting of a front shell 1a and a rear shell 1b.
Connect the tip of the master cylinder 2 to the shaft of the
The base of this master cylinder 2 is fixed to the vehicle body 3. A valve body 5 integrally equipped with a power piston 4 is provided inside the shell 1 so as to be able to reciprocate along the axial direction of the shell 1. The front shell 1
It is divided into a constant pressure chamber 7 on the a side and a variable pressure chamber 8 on the rear shell 1b side.

The valve body 5 is generally formed into a cylindrical shape as a whole, and its tip can protrude to the outside through an opening 9 formed in the shaft of the front shell 1a while being kept airtight by the base 10a of the sealing member 10. ing. Then, by folding the tip end 10b of the seal member 10 from the intermediate portion to the inside of the base portion 10a and connecting it to the tip portion of the valve body 5, the seal member 10 can be used as a dust cover for the sliding portion between the valve body 5 and the base portion 10a. We are using. Further, the valve body 5 is normally held in the non-operating position shown in the drawing, in which it is in contact with the housing 12 of the master cylinder 2, by means of an elastic force mounted between the valve body 5 and the front shell 1a, or by a return spring 11.

A valve mechanism 15 for switching the fluid circuit is provided inside the valve body 5, and this valve mechanism 15 is connected to an annular first valve seat 1 formed on the inner peripheral surface of the valve body 5.
6, a second valve seat 18 formed at the tip of the input shaft 17 inside the first valve seat 16, and further seated on each valve seat 16, 18 from the front side in the operating direction of the power piston 4, that is, from the left side in FIG. A valve body 19 is provided. In the illustrated non-operating state, the valve body 19 is seated on the first valve seat 16 by a spring 21 elastically loaded between the valve body 19 and a closing member 20 that closes the shaft hole of the valve body 5. The second valve seat 18 of the input shaft 17 is separated from the valve body 19 seated on the first valve seat 16 by a spring 22 that is elastically loaded between the closing member 20 and the input shaft 17.

The valve body 19 has a cylindrical seal portion 19 on its inner circumference.
a, and by connecting this cylindrical seal portion 19a to the closing member 20, the cylindrical seal portion 19
a, a plurality of axial passages 23 that form a space by the outer periphery of a, the closing member 20 and the seal portion between the valve body 19 and the first valve seat 16, and the space is formed in the closing member 20, and the closing member 20 and seal member 1
It is communicated with the atmosphere through a filter 24 provided between the tip 10b of the 0 and the tip 10b of the 0. On the other hand, the inner circumference of the cylindrical seal portion 19a, the closing member 20, and the input shaft 1
7, and the second valve seat 18 and valve body 19 of the input shaft 17
The space formed by the sealing portion of the closing member 20 includes a plurality of radial passages 2 formed in the closing member 20 so as not to communicate with the axial passage 23 of the closing member 20.
5 and a passage 26 formed in the valve body 5 to communicate with the constant pressure chamber 7. Furthermore, the valve body 19
and the seal portion between the first valve seat 16 and the valve body 19 and the second valve seat 16.
A space between the valve seat 18 and the seal portion is communicated with the variable pressure chamber 8 via an axial passage 27 formed in the valve body 5 .

The input shaft 17 consists of a first input shaft 17a and a second input shaft 17b, and the second valve seat 18 is formed at the tip of the first input shaft 17a. The first input shaft 17a is slidably passed through the shaft portion of the housing 12 of the master cylinder 2, and the second input shaft 17a is connected to the end portion of the first input shaft 17a via a connecting member 30.
The distal end spherical portion 17c of the second input shaft 17b is pivotally supported, and the distal end of the second input shaft 17b is linked to a brake pedal (not shown). An output shaft 32 for transmitting the thrust of the power piston 4 to the piston 31 of the master cylinder 2 is slidably fitted on the outer periphery of the first input shaft 17a, and in this embodiment, the output shaft 32 and the piston 31 is constructed from an integrated stepped hollow tube.

The tip of the output shaft 32 extends to the vicinity of the second valve seat 18 of the input shaft 17, and a reaction disk 34 is disposed on the back side of a nut member 33 screwed onto the tip.
The thrust force applied to the shaft can be received through the reaction disk 34 and the nut member 33. Further, a cylindrical connecting member 35 is screwed onto the outer periphery of the second valve seat 18 of the input shaft 17, and the nut member 33 and the reaction disk 34 are slidably housed within the cylindrical connecting member 35. At the same time, the base of the connecting member 35 is curved inward and positioned on the back side of the reaction disk 34, so that the reaction force from the reaction disk 34 can be transmitted to the brake pedal via the connecting member 35 and the input shaft 17. That's what I do.

The output shaft 32 is maintained liquid-tight by a pair of seal members 40 and 41 provided on the housing 12 and sleeve 13 of the master cylinder 2, and slidably passes through the shaft portion of the housing 12. In the illustrated embodiment, the master cylinder 2 is constructed as a two-system master cylinder, with the piston 31 integrated with the output shaft 32 serving as the primary piston. Then, the piston 42 on the secondary side maintains liquid tightness and connects the output shaft 32 and the sleeve 1.
The piston 42 is slidably fitted between the output shaft 32 and the output shaft 32, and normally a spring 43 elastically loaded between the pistons 31 and 42 causes the piston 42 to come into contact with a stop ring 44 provided on the output shaft 32.

The above-mentioned two-system master cylinder 2 can be constructed in the same manner as a conventionally known two-system master cylinder, except that the pistons 31 and 42 have a special structure. Omitted. In addition, in FIG. 1, 45 is the pressure chamber of one system, 46 is the pressure chamber of the other system, 4
7 is a reservoir.

In the above configuration, in the non-operating state shown in the figure, the power piston 4 and the bubble body 5 are in contact with the housing 12 of the master cylinder 2 by the return spring 11, and the input shaft 17 is urged rightward together with the output shaft 32 by the spring 22. is,
The reaction disk 34 is stopped in a slightly compressed state with respect to the valve body 5 which is stopped in contact with the housing 12. In this state, the valve body 19 is seated on the first valve seat 16 to cut off communication between the variable pressure chamber 8 and the atmosphere, and the valve body 19 and the second valve seat 18 are separated from each other to form the variable pressure chamber 8 and the constant pressure chamber. It connects 7 spaces. Therefore, the negative pressure introduced into the constant pressure chamber 7 from the negative pressure inlet (not shown) provided in the front shell 1a is transmitted through the passages 26, 25, the gap between the valve body 19 and the second valve seat 18, and the passage 27. The power piston 4 is introduced into the variable pressure chamber 8 through the power piston 4, and there is no pressure difference between the front and rear of the power piston 4.

When the brake pedal (not shown) is depressed from this state and the input shaft 17 is moved to the left, the second valve seat 18 first seats on the valve body 19 to cut off communication between the constant pressure chamber 7 and the variable pressure chamber 8. As the input shaft 17 continues to move to the left, the valve body 19 is removed from the first valve seat 16. Then, the atmosphere is introduced into the variable pressure chamber 8 through the filter 24, the passage 23, the gap between the valve body 19 and the first valve seat 16, and the passage 27, and the power piston 4
In addition, a pressure difference is generated before and after the valve body 5, and the valve body 5 is moved to the left against the return spring 11.

When the valve body 5 moves to the left, its thrust is transmitted to the primary side piston 31 of the master cylinder 2 via the reaction disk 34, nut member 33, and output shaft 32, and this piston 31 moves to the left and enters the pressure chamber 45. When brake fluid pressure is generated, the secondary piston 42 moves to the left and brake fluid pressure is generated in the pressure chamber 46. The brake fluid pressure generated in each pressure chamber 45, 46 is supplied to a wheel cylinder (not shown) to perform a braking operation, as is conventionally known. During this time, as described above, the brake reaction force is transmitted from the reaction disk 34 to the brake pedal via the connecting member 35 and the input shaft 17.

It is clear that when the depression force on the brake pedal is released from the braking state, the valve mechanism 15 switches to the state shown in the figure, and therefore returns to the non-operating state described above. At this time, since the valve body 5 is biased to the right by atmospheric pressure, the return spring 11 can be a lightweight one with weaker elasticity than conventional ones, or the return spring 11 can be 11 can be omitted, the weight of the brake booster can be reduced accordingly.

In this embodiment, since the piston 31 of the master cylinder 2 is formed integrally with the output shaft 32, there is no need for a connecting means or a sealing member between the output shaft 32 and the piston 31, and the configuration is simplified. Furthermore, even if the two are configured separately, the connection means between the output shaft 32 and the piston 31 will be much simpler and more rigid than in the conventional configuration in which the output shaft is provided inside the input shaft. , the connecting portion can be made smaller and lighter.

Next, FIG. 2 shows the main part of another embodiment of the present invention, in which the input shaft 117 and the reaction disk 134 are interlocked from the inside. In the figure, an annular groove 150 is formed in the shaft portion of the valve body 105, and an annular member 151 is slidably fitted into the annular groove 150, and the front end face of the annular member 151 and the valve body on the outer periphery of the annular member 151 are formed. 105 are both opposed to the rear end surface of the reaction disk 134. And the above valve body 1
A pair of axial grooves 152 are formed in the upper and lower positions of the annular groove 150 in the output shaft 1.
A pin 154 is formed with a pair of upper and lower slits 153 along the axial direction in 32 and press-fitted into the input shaft 117.
Both ends of the annular member 151 protrude from each slit 153 and face the rear end surface of the annular member 151.
Also, a cup-shaped member 15 is attached to the tip of the output shaft 132.
5 and store the reaction disk 134 therein, and this reaction disk 1
The front end surface of the cup-shaped member 155 and the inner wall end surface of the cup-shaped member 155 are opposed to each other. Furthermore, a second valve seat 118 is provided at the tip of the input shaft 117, which is configured separately from the input shaft 117.

The rest of the structure is substantially the same as that of the previous embodiment, and the same or corresponding parts as those of the previous embodiment are designated by the same reference numerals as in FIG. 1 plus 100. There is.

In this embodiment, the same operation as in the above embodiment is obtained, and the reaction force at that time is transmitted from the output shaft 132 to the input shaft 117 via the reaction disk 134, the annular member 151 and the pin 154.
Furthermore, in this embodiment, the input shaft 117 and the annular member 151 are interlocked by the pin 154;
Since no increased acting force is applied to the input shaft 117, the strength can be reduced compared to the conventional case in which a protrusion such as a pin is provided on the output shaft, and the input shaft 117 can be made smaller and lighter.

Note that the valve mechanism is not limited to that of the above-described embodiment, and a two-valve, two-seat type valve mechanism may be used.

As described above, according to the present invention, it is possible to simplify the connection structure between the output shaft and the piston of the master cylinder, thereby making it possible to reduce the size and weight.

[Brief explanation of drawings]

FIG. 1 is a half sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view of essential parts showing another embodiment of the invention. 1...Ciel, 2,102...Master cylinder, 4,104...Power piston, 5,105
... Valve body, 15,115 ... Valve mechanism, 1
7,117...Input shaft, 31...Piston, 3
2,132...Output shaft, 34,134...Reaction disk.

Claims (1)

[Claims] 1. A power piston slidably disposed within a shell, a valve mechanism and a reaction disk disposed within a valve body of the power piston shaft,
A master cylinder is connected to the brake pedal side of the above shell, and the master cylinder is slidably penetrated through the master cylinder and interlocked with the above valve mechanism, and this valve mechanism is operated to create a fluid pressure difference before and after the above power piston. an input shaft, and an output shaft that interlocks the power piston and the piston of the master cylinder, and an end surface provided on the valve body and an end surface provided on the input shaft are opposed to the brake pedal side end surface of the reaction disk, and , the end surface provided on the output shaft is opposed to the opposite end surface of the reaction disk, and the output shaft is slidably fitted on the outer periphery of the input shaft, and the piston of the master cylinder is provided on the output shaft. A brake booster characterized by: