JPS6114926Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a brake booster, especially a booster used in the power braking system of automobiles, which uses the brake fluid pressure generated in the master cylinder during braking as a reaction force that is transmitted to the brake pedal side. Regarding the mechanism, the purpose is to improve the durability of the pressurized deformation member that constitutes this reaction force mechanism.

Conventionally, in a brake booster, a valve mechanism is actuated by an operating rod linked to a brake pedal to change the fluid pressure differential applied to the piston, and an operating pressure is generated in the brake-side driven rod fitted with the piston. The cylinder is driven and braking hydraulic pressure is supplied to the brake cylinder.The reaction force mechanism that transmits the hydraulic reaction force generated in the master cylinder to the brake pedal side is the insertion part of the driven rod in the piston. A pressure deformable member such as rubber is interposed between the valve plunger and the valve plunger at the tip of the operating rod.

The pressure deformation member deforms along the stepped inner diameter portion of the piston into which it is fitted even with a slight hydraulic reaction force, and transmits the reaction force to the brake pedal side. It is necessary to use one that is sufficiently flexible to allow for this.

However, when a flexible pressure deformation member is used, especially when the hydraulic reaction force becomes large, the above-mentioned pressure is applied even to the small gap between the driven rod and valve plunger that constitute the reaction force mechanism and the inner wall surface of the piston. A part of the pressurized deformable member tends to bite, and in particular, the contact portion between the end face of the valve plunger and the pressurized deformable member becomes extremely brittle, resulting in a disadvantage that its durability is significantly reduced.
For this purpose, an elastic body with higher strength than the pressure deformation member is already attached to the end face of the pressure deformation member on the valve plunger side to eliminate the situation in which the valve plunger made of a rigid body such as metal directly presses the pressure deformation member. A device designed to improve durability (Japanese Utility Model Publication No. 50-138493) is known, but this device not only requires bonding work between the pressurized deformation member and the elastic body, but also the bonding of the elastic body. The pressurized deformable member is a device that is inserted into the piston, so there is a problem with the directionality of the device, which requires confirmation of its insertion direction, which makes assembly work difficult. There were problems such as the need to prepare a large number of deformable members.

Further, the valve plunger is thereby slidably fitted to the piston through an axial gap in opposition to the large-diameter pressure deformation member, so that the fitting portion of the pressure deformation member and the valve plunger A stepped portion is formed in the fitting portion of the valve plunger, and when a conventional pressurized deformable member that does not have a reinforcing elastic body is deformed, a portion of the pressurized deformable member that bulges toward the stepped portion is connected to the valve plunger and its fitting portion. It also enters the fitting gap between the valve plunger and the valve plunger, causing the above-mentioned problem of severe jamming and embrittlement of the pressure deformation member. , which exerts a dominant influence directly related to the quality of the brake feeling, and this is the jumping characteristic of the brake booster (the output generated until the reaction force is transmitted to the input side through the pressurized deformation member at the start of brake operation) For example, if a high-strength elastic body is attached to the above-mentioned pressurized deformation member, and the above-mentioned gap is increased due to the incorrect mounting direction of the pressurized deformation member, the above-mentioned jumping load of the above-mentioned jumping characteristic There was a risk that this would result in an impactful brake feeling that was significantly increased. The above-mentioned jamming and brittle deformation of the pressurized deformation member also affects the maintenance of the above-mentioned gap, making it difficult to maintain the brake feeling.
In addition, the high-strength elastic body adhered to the pressurized deformation member lacks flexibility and is difficult to deform when it moves toward the valve plunger even during normal operation, causing a hypersensitive response to the jumping characteristics, and manufacturing errors may cause brake failure. This has the drawback of increasing variations in the jumping characteristics of the booster.

The present invention has been made in order to solve the above-mentioned problems, and the above-mentioned valve plunger is slidably fitted to the above-mentioned pressure deformation member having a larger diameter through a gap, and , an annular step is formed on the end face of the valve plunger facing the pressure deformation member, an elastic body having higher strength than the pressure deformation member is integrally fitted into the step, and the elastic body allows the pressure deformation member to By configuring at least the peripheral edge of the end face of the valve plunger, there is no need for bonding work between the elastic body and the pressure deformation member, and the directionality of the pressure deformation member is eliminated, thereby improving assembly workability. At the same time, it is possible to eliminate the engagement of the contact end surface of the pressurizing deformable member facing the valve plunger, making it easier to manage the gap between the pressurizing deformable member and the valve plunger, that is, maintain the jumping characteristic, and obtain a good brake feeling. This is how it was done.

The present invention will be explained below with reference to the illustrated embodiments.
1 is a closed shell body in which a front shell body 2 and a rear shell body 3 are brought into contact with each other, and a diaphragm 4 is clamped and supported between them;
is a piston that is inserted into this shell and has the inner circumferential edge of the diaphragm 4 fixed on its back circumferential surface, and this piston and diaphragm 4 partition the inside of the shell 1 into a front chamber 6 and a rear chamber 7, and A rear cylindrical portion 8 is slidably projected from the opening of the rear shell 3 via a seal 9. A return spring 10 is stretched between the front surface of the piston and the end wall of the front chamber 6, and presses the piston 5 against the stepped portion of the rear shell 3 via the spot-like protrusion 11 of the diaphragm 4 on the back surface thereof. , 12 is a fitting hole provided at the center of the front surface of the piston 5; 13 is a driven rod having a base end fitting portion 14 slidably fitted into the fitting hole; The output is transmitted through the seal 15 in an airtight manner to a master cylinder (not shown). 16 is a negative pressure pipe opened in the end wall of the front chamber 6 and connected to a negative pressure source such as an engine intake pipe; 17 is a communication passage that penetrates the inside of the piston 5 and opens inside the cylindrical portion 8; and 18 is a piston. An internal chamber 19 communicating with the fitting hole 12 in 5
This is another communication path provided to communicate the rear chamber 7 and the rear chamber 7.

The operating rod 20 is inserted through the air cleaner 21 from the rear opening of the cylindrical portion 8, and the spherical tip 22 has a valve plunger 23 slidably fitted into the internal chamber 19 of the piston 5. The end is caulked, and the rear end is linked to a brake pedal (not shown). Reference numeral 24 denotes a valve member surrounding this operating rod and provided at the rear of the spherical portion 23, which has a configuration in which a cylindrical plate member is covered with an elastic member such as rubber, and the rear edge enlarged portion 25 is located in the middle of the cylindrical portion 8. It is fixed at the inner circumference position. Reference numeral 26 indicates a receiving portion 28 attached to the intermediate flange portion 27 of the operating rod 20 and the valve member 2.
A valve return spring provided between the enlarged portion 25 of 4, 29
30 is a valve biasing spring provided between the front edge of the receiving portion 28 and the rear step portion of the valve member 24; 30 is the fitting hole 12;
Inside the valve plunger 23 and the driven rod insertion part 1
An elastic body 31, which is a pressure deformation member such as rubber, fitted between the valve plunger 23 and the pressure deformation member 30, is provided on the outer periphery of the end surface of the valve plunger 23 on the pressure deformation member 30 side.
is crowned. The elastic body 31 is the pressurized deformation member 3
It is formed into an annular shape from an elastic material such as rubber or plastic having a strength (hardness) greater than zero, and its inner diameter is determined so that it can be fitted onto the annular stepped portion 23a of the valve plunger 23 with a tightness. The outer diameter of the valve plunger 23 is approximately the same as the diameter of the tip of the valve plunger 23. The end face of the elastic body 31 is flush with the end face of the valve plunger 23, that is, both end faces are located on the same plane. Reference numeral 32 indicates a key member that spans the intermediate reduced diameter portion of the valve plunger 23 with a free movement interval left, and reference numeral 33 indicates a bellows provided to cover the respective open ends of the cylinder portion 8 and the rear shell body 3.

Since it has the above-mentioned configuration, when this booster is not in operation, the valve return spring 2 is activated as shown in the figure.
6, the valve plunger 23 is pressed rearward together with the operating rod 20 and is in a retracted position where the front edge of the reduced diameter portion of the valve plunger 23 is brought into contact with the key member 31, and the valve member 24 is biased by the valve biasing spring 29. While pressing its leading edge against the trailing edge of the valve plunger 23,
Also, in this position, the opening edge 3 of the piston internal chamber 19
4 and the front edge of the valve member 24 are separated from each other. Therefore, negative pressure is generated in the front chamber 6, the communication passage 17,
The inner chamber 19 communicates with the rear chamber 7 via another communication passage 18 , and the piston 5 is biased by the return spring 10 into the retracted position shown, while the atmospheric pressure is supplied via the air cleaner 21 to the inner position of the valve plunger 23 . Reached here is blocked. Then, when the brake pedal is stepped on and the operating rod 20 moves forward against the valve return spring 26, the valve member 24 first comes into contact with the opening edge 34 of the internal chamber 19, cutting off communication between the communication passage 17 and the internal chamber 19. Then, the rear edge of the valve plunger 23 is separated from the front edge of the valve member 24, and air flows into the internal chamber 19.
and another communication passage 18 into the rear chamber 7, the piston 5 moves forward against the return spring 10, and the driven rod 13 actuates the master cylinder and feeds the brake hydraulic pressure to the brake cylinder. leading to.

When the pedal force is removed from the brake pedal, the above-mentioned operation is reversed, and the valve plunger 23 closes the atmosphere side, and the leading edge of the valve member 24 closes the inner chamber 1.
9, the rear chamber 7 communicates with the front chamber 6 again, the air in the rear chamber 7 is sucked out to the engine side, and the piston 5, operating rod 20, etc. return to the operating position shown.

During the above-mentioned brake operation, the hydraulic reaction force of the master cylinder causes the fitting part 14 of the driven rod 13 to
compressively deforms the pressurized deformable member 30, and this compressive deformation transmits a reaction force to the valve plunger 23, giving the brake operator a feeling of brake reaction force via the operating rod 20. By the way, the flexible pressurizing deformation member 30 has a tendency to get stuck in the delicate gap around the valve plunger 23 during this compression deformation as described above, but in the present invention, the outer periphery of the end face of the valve plunger 23 is made of elastic material. Since the body 31 is provided, local deformation of the pressure deformation member 30 as described above is prevented. That is, since the elastic body 31 is made of an elastic material having higher hardness and strength than the pressure deformation member 30, when the pressure deformation member 30 is deformed, the elastic body 31 is also compressed and deformed at the same time, and the pressure deformation member 30 The above local deformation of can be absorbed. Therefore, the pressurized deformable member 30 is prevented from becoming jammed or brittle, and since the elastic body 31 itself is harder than the pressurized deformable member 30 and is integrally provided with the valve plunger 23, local deformation is prevented. Therefore, the pressure deformation member 30 and the elastic body 31
Both can maintain their initial performance for a long time even after repeated use.

2A to 2C show various examples of shapes of the elastic body 31 provided on the end face of the valve plunger 23, and FIG. The figure shows a product that is designed to completely prevent it from coming off. On the other hand, in FIGS. 2-3B to 3-C, the elastic body 31 and the valve plunger 23 can be easily connected by providing an appropriate tightening margin to the elastic body over the entire end face of the valve plunger 23, or by using a tapered surface as shown in the figure. They can be integrated, and the same effects as above can be obtained. It goes without saying that the elastic body 31 can be provided on the valve plunger 23 by using an adhesive or by using an adhesive together.

As described above, according to the present invention, it is possible to prevent local deformation of the pressure deformation member around the valve plunger and improve durability, and the elastic body can be provided integrally with the valve plunger in advance. So,
This has the effect of improving assembly workability and reducing costs.

In the present invention, an annular step is formed on the end face of the valve plunger facing the pressurizing deformation member, and a high-strength elastic body is integrally fitted into this step, and the elastic body causes the above-mentioned valve to open. Since at least the peripheral portion of the end face of the plunger is configured, not only can accurate and reliable integral connection between the valve plunger and the elastic body be easily achieved, but also
The elastic body can sufficiently cover and protect the periphery of the end face of the valve plunger, which is easily damaged during handling, and has the advantage that the finished dimensional accuracy of the tip end of the valve plunger can be made gentle.
In particular, in the present invention, local deformation around the valve plunger can be prevented without making any changes to the pressurized deformation member itself.
It is extremely effective in that it does not impose a direction of insertion on the pressure deformable member, allows free deformation during operation and is unchanged from conventional ones, and can permanently improve durability. It can be said that it is a thing.
Moreover, in the present invention, since the elastic body is provided on the valve plunger side, it is possible to eliminate the conventional work of gluing the pressurized deformation member and the elastic body, and also to manage the gap between the valve plunger and the pressurization deformation member. This has the effect of making it possible to obtain the desired brake feeling that is well maintained and suppresses variations in the jumping characteristics.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the brake booster according to the present invention, and FIGS. 2A to 2C are cross-sectional views of essential parts showing other embodiments of the present invention. 5. Piston, 13. Driven rod, 14. Fitting part, 20. Operating rod, 23. Valve plunger.
30... Pressure deformation member, 31... Elastic body.

Claims (1)

[Scope of utility model registration request] A valve mechanism is actuated by an operating lever linked to the brake pedal to control the fluid pressure applied to the piston.
An elastic member interposed between the fitting part of the driven rod and the valve plunger at the tip of the operating rod generates operating pressure in the brake-side driven rod fitted with this piston and absorbs the brake reaction force generated in the driven rod. In the brake booster that transmits pressure to the brake pedal via a pressurizing deformable portion consisting of a body, the valve plunger is slidably slidable on the piston through a gap facing the pressurizing deformable member having a larger diameter. At the same time, an annular stepped portion is formed on the end face of the valve plunger facing the pressurized deformable member, and an elastic body having a higher strength than the pressurized deformable member is integrally fitted into the stepped portion. A reaction force mechanism for a brake booster, characterized in that at least a peripheral edge portion of the end face portion of the valve plunger is formed by a body.