CN221162704U

CN221162704U - Brake master cylinder

Info

Publication number: CN221162704U
Application number: CN202323558508.7U
Authority: CN
Inventors: 房孝朴; 李昊军
Original assignee: Bosch Automotive Products Suzhou Co Ltd
Current assignee: Bosch Automotive Products Suzhou Co Ltd
Priority date: 2023-12-26
Filing date: 2023-12-26
Publication date: 2024-06-18
Anticipated expiration: 2033-12-26

Abstract

A brake master cylinder includes a first piston, a second piston, a first spring, a second spring, and an adapter, the rear end of the first piston having a sensor frame, an elastic buffer ring being disposed in a recess formed in a rear end face of the sensor frame or an end wall of the adapter, and being axially compressed between the rear end face of the sensor frame and the end wall of the adapter under the urging force of the first spring in a static state of the brake master cylinder. The elastic buffer ring can suppress the impact between the sensor holder and the adapter.

Description

Brake master cylinder

Technical Field

The present application relates to a master cylinder.

Background

A brake master cylinder is typically included in a vehicle brake system. The master cylinder generally includes a cylinder body, a first piston and a second piston sliding in the cylinder body, an input rod driven by a brake pedal to push the first piston, and an adapter fixed to the rear end of the cylinder body. The rear portion of the first piston is received in an adapter that is capable of defining a rearward stroke of the first piston. The first piston pushes the second piston through the first spring. After a driver presses a brake pedal to apply braking and then releases the brake pedal quickly, the first piston can move backwards quickly under the action of the first spring and return to the original position, and the sensor frame at the rear end of the first piston can strike the adapter to generate striking noise and vibration, so that bad driving feeling is given to the driver.

Disclosure of utility model

It is an object of the present application to provide an improved master cylinder that is capable of preventing noise and vibration from being generated by a sensor mount at the rear end of a first piston striking an adapter after a brake pedal is released quickly.

To this end, the present application provides, in one aspect thereof, a master cylinder comprising:

a cylinder;

a first piston having a front portion axially slidably inserted into the cylinder;

a second piston slidably disposed in the cylinder;

A first spring arranged in an axially compressed manner between the first piston and the second piston;

A second spring configured to apply a rearward axial thrust to the second piston;

An adapter secured to the rear end of the cylinder and including a cylindrical body and a radially inwardly extending end wall at the rear end of the body, the rear portion of the first piston being exposed from the rear end of the cylinder and located within the adapter;

A sensor holder fixed to a rear end of the first piston, facing an end wall of the adapter, configured to hold a magnet of the brake pedal travel sensor;

An elastic buffer ring is arranged in a pit formed on the rear end surface of the sensor frame or the end wall of the adapter, and is axially compressed between the rear end surface of the sensor frame and the end wall of the adapter under the thrust of the first spring under the static state of the brake master cylinder.

In one embodiment, the buffer ring has a cross-sectional dimension of an exposed portion exposed from the recess in a natural state in which the buffer ring is not axially compressed that is smaller than a cross-sectional dimension of an embedded portion embedded in the recess.

In one embodiment, the cross section of the exposed part of the buffer ring exposed from the pit is trapezoid, partial circular or partial elliptic in a natural state of not being compressed axially.

In one embodiment, the buffer ring has an exposed portion exposed from the recess in a natural state in which the buffer ring is not compressed axially, and the exposed portion is reduced in material amount relative to an embedded portion embedded in the recess.

In one embodiment, the side of the buffer ring facing away from the recess is corrugated or zigzag.

In one embodiment, the buffer ring is a continuous annular ring or a discrete annular ring.

In one embodiment, the buffer ring is composed of a plurality of circular arc segments which are discrete in the circumferential direction.

In one embodiment, the variation in the static thickness of the damping ring in the static state of the master cylinder is within the allowable tolerance of the brake pedal travel sensor, and the outer diameter of the damping ring is smaller than the outer diameter of the sensor holder.

In one embodiment, the buffer ring has a static thickness equal to or greater than the pit depth.

In one embodiment, the buffer ring is made of an elastomeric material.

According to the brake master cylinder disclosed by the application, the elastic buffer ring is arranged between the sensor frame at the rear end of the first piston and the end wall of the adapter, and after a driver rapidly releases the brake pedal, the buffer ring can buffer the impact of the sensor frame on the adapter when the first piston is reset backwards, so that impact noise and vibration are reduced or even eliminated, and good driving feeling can be provided for the driver.

Drawings

The foregoing and other aspects of the application will be more fully understood and appreciated from the following detailed description taken with reference to the accompanying drawings, in which:

Fig. 1 is a schematic cross-sectional view of a main portion of a master cylinder of the present application;

FIG. 2 is a partial cross-sectional view of an elastomeric buffer ring disposed on a sensor mount at the rear end of a first piston in one embodiment of the master cylinder of the present application;

FIG. 3 is a schematic illustration of the sizing of the elastomeric buffer ring in the embodiment of FIG. 2;

FIGS. 4-8 are schematic illustrations of some modifications of the elastomeric cushion ring of the embodiment of FIG. 2;

Figure 9 is a partial cross-sectional view of a resilient cushion ring disposed at an end wall of an adapter in another embodiment of a master cylinder of the present application,

Detailed Description

The present application relates generally to a master cylinder in a vehicle. An exemplary construction of the master cylinder is shown in fig. 1.

As shown in fig. 1, the master cylinder includes: a cylinder 1 in which an axially extending main hole is formed; a first piston 2, the front portion of which is axially slidably inserted into the main hole; a second piston 3 slidably disposed in the main hole at a front side of the first piston 2; a first spring 4 disposed in an axially compressed manner between the first piston 2 and the second piston 3, the first spring 4 applying a rearward axial thrust to the first piston 2 and a forward axial thrust to the second piston 3; a second spring 5 arranged to apply a rearward axial thrust to the second piston 3; an adapter 6 fixed to the rear end of the cylinder 1 and having a substantially cylindrical structure including a cylindrical main body 6a, an outward flange 6b at the front end of the main body 6a, and a radially inward extending end wall 6c at the rear end of the main body 6a, the flange 6b being fixed to the rear end of the cylinder 1, the end wall 6c defining a through hole 6d at the center, the rear portion of the first piston 2 being exposed from the rear end of the cylinder 1 and being located in the adapter 6; an input rod 7, the front portion of which is inserted into the rearward-open inner bore of the first piston 2 through the through-hole 6d and is fixed in the first piston 2 by a fixing assembly 8, the rear end (not shown) of the input rod 7 being configured to be driven by a brake pedal (not shown); a sensor holder 9 fixed to the rear end of the first piston 2, the sensor holder 9 holding a magnet carrier 10, the magnet carrier 10 being provided with a magnet (not shown), the axial position of which is sensed by a sensing device (not shown) mounted on the cylinder to detect the axial position of the input rod 7 and thereby determine the brake pedal stroke. The magnet and the sensing device constitute a brake pedal travel sensor.

The first piston 2 is made of metal, for example, aluminum, and the sensor frame 9 is made of aluminum and is press-riveted to the rear end periphery of the first piston 2. The rear end face of the sensor holder 9 is generally flush with the rear end face of the first piston 2 or slightly rearwardly beyond the rear end face of the first piston 2. The adapter 6 is typically made of plastic or aluminum. The rear end surface of the sensor holder 9 faces the inner peripheral portion of the end wall 6c of the adapter 6 in the substantially axial direction.

After the brake pedal is depressed, the brake pedal drives the input rod 7 to move forward, and the input rod 7 pushes the first piston 2 to move forward. After the driver releases the brake pedal, the first spring 4 pushes the first piston 2 backward. In order to avoid that the rear end face of the sensor holder 9 hits the end wall 6c of the adapter 6 violently when the first piston 2 moves backward, an elastic buffer ring 11 is provided between the rear end face of the sensor holder 9 and the end wall 6c of the adapter 6.

According to one embodiment of the application, as shown in fig. 1, 2, a buffer ring 11 is provided on the rear end face of the sensor holder 9, facing the end wall 6c of the adapter 6. The buffer ring 11 is made of an elastomer material such as rubber, silicone, or the like, and is fixed to the rear end surface of the sensor frame 9 by bonding, overmolding, form fitting, or the like. For this purpose, a recess for accommodating the buffer ring 11 is formed on the rear end face of the sensor holder 9, which recess faces the inner peripheral portion of the end wall 6c, into which recess the buffer ring 11 is fixed.

Referring to fig. 3, the buffer ring 11 has an outer diameter D, a thickness H0 in a natural state (when not compressed), an insertion thickness H1 (i.e., a pit depth) inserted into the pit, and a static thickness H2 after the brake master cylinder is compressed due to the action of the first spring 4 in a static state (when the brake pedal is not depressed). Each thickness is measured in the axial direction.

The outer diameter D of the buffer ring 11 should be smaller than the outer diameter of the sensor holder 9.

The outer diameter D, the free state thickness H0, and the insertion thickness H1 are designed such that the amount of change in the static thickness H2 (or the protruding height of the cushion ring obtained by subtracting the insertion thickness H1 from the static thickness H2) (the change due to factors such as the use time and the use state of the master cylinder) is within the allowable tolerance of the brake pedal stroke sensor. With this condition satisfied, the static thickness H2 is generally greater than the embedded thickness H1. According to this design, there is a certain gap between the rear end face of the sensor holder 9 and the end wall 6c of the adapter 6 in the static state of the brake master cylinder, as shown in fig. 2.

Alternatively, it may be designed such that the static thickness H2 is equal to the embedding thickness H1. According to this design, the rear end face of the sensor holder 9 is in contact with the end wall 6c of the adapter 6 at a static state of the brake master cylinder without a gap. This design makes the detection accuracy of the brake pedal stroke sensor unaffected by the cushion ring 11.

The buffer ring 11 may have a rectangular cross section as shown in fig. 2 and 3. However, mainly in order to facilitate the axial compression of the buffer ring 11, the cross section of the buffer ring 11 may be designed such that, in its natural state, the cross section of the exposed portion thereof emerging from the recess is smaller than the cross section of the embedded portion embedded in the recess, preferably gradually decreasing in size towards the end wall 6c of the adapter 6.

For example, in the modification shown in fig. 4, the cross section of the embedded portion of the buffer ring 11 embedded in the pit is rectangular, and the cross section of the exposed portion exposed from the pit is trapezoidal. In the modification shown in fig. 5, the cross section of the embedded portion of the buffer ring 11 embedded in the recess is rectangular, and the cross section of the exposed portion exposed from the recess is partially (semi) circular or partially (semi) elliptical. Other cross-sectional shapes of the buffer ring 11 having similar characteristics can be designed.

Or the side of the buffer ring 11 facing the end wall 6c of the adapter 6 may reduce the amount of material relative to the embedded portion. For example, as shown in the expanded view of the buffer ring 11 in fig. 6, the side of the buffer ring 11 facing the end wall 6c of the adapter 6 is designed to be corrugated, which facilitates the axial compression of the buffer ring 11. Alternatively, it is conceivable to design the side of the buffer ring 11 facing the end wall 6c of the adapter 6 as triangular-shaped saw-tooth, square-shaped saw-tooth, etc.

Further, the buffer ring 11 may be designed as a complete continuous ring shape. Alternatively, the buffer ring 11 may be designed as a discrete ring, i.e. the buffer ring 11 is composed of a plurality of circular segments which are discrete in the circumferential direction. For example, in the modification shown in fig. 7, the buffer ring 11 includes two circular arc segments (for example, two 90-degree circular arc segments) which are uniformly distributed in the circumferential direction and have equal arc lengths, as viewed in the axial direction. As another example, in the modification shown in fig. 8, the buffer ring 11 includes one long arc segment and a plurality of (two are shown) short arc segments which are uniformly distributed in the circumferential direction and have equal arc lengths, as viewed in the axial direction. In general terms, the buffer ring 11 may comprise short arc segments which are uniformly or non-uniformly distributed in the circumferential direction and have equal or unequal arc lengths.

According to another embodiment of the application, as shown in fig. 9, a buffer ring 11 is provided on the end wall 6c of the adapter 6, facing the rear end face of the sensor holder 9.

The buffer ring 11 in the embodiment shown in fig. 9 may have various features of the buffer ring 11 described previously.

Specifically, in the embodiment shown in fig. 9, the buffer ring 11 is made of an elastomeric material, such as rubber, silicone, or the like, and is fixed to the end wall 6c of the adapter 6 by means of bonding, overmolding, form fitting, or the like. The inner edge of the buffer ring 11 may be flush with the inner edge of the end wall 6c, as shown in fig. 9. Or the inner edge of the buffer ring 11 may be located radially outward of the inner edge of the end wall 6 c. A recess for accommodating the buffer ring 11 is formed in the end wall 6c, the recess facing the rear end face of the sensor holder 9, the buffer ring 11 being fixed into the recess.

Similarly, in the embodiment shown in fig. 9, the outer diameter of the cushion ring 11, the thickness in the free state (when not compressed), the embedded thickness in the embedded recess are designed such that the amount of change in the static thickness after the static state of the brake master cylinder (the state when the brake pedal is not depressed) is compressed by the action of the first spring 4 is within the allowable tolerance range of the brake pedal stroke sensor. The static thickness of the buffer ring 11 is typically greater than the embedded thickness so that there is a gap between the rear end face of the sensor mount 9 and the end wall 6c of the adapter 6 in the static state of the brake master cylinder, as shown in fig. 9. Alternatively, it may be designed such that the static thickness is equal to the embedded thickness. According to this design, the rear end face of the sensor holder 9 is in contact with the end wall 6c of the adapter 6 at a static state of the brake master cylinder without a gap.

Similarly, in the embodiment shown in fig. 9, the buffer ring 11 may have a rectangular cross section. Alternatively, the cross section of the buffer ring 11 may be designed such that, in its natural state, the cross section of the exposed portion exposed from the recess is smaller than the cross section of the embedded portion embedded in the recess, preferably gradually decreasing toward the rear end face of the sensor holder 9. For example, the cross section of the embedded portion of the buffer ring 11 embedded in the pit is rectangular, and the cross section of the exposed portion exposed from the pit is trapezoidal. Or the cross section of the embedded part of the buffer ring 11 embedded in the pit is rectangular, and the cross section of the exposed part exposed from the pit is semicircular or semi-elliptical.

Also in the embodiment shown in fig. 9, the side of the buffer ring 11 facing the rear end face of the sensor holder 9 can be reduced in material amount relative to the embedded portion. For example, the side of the buffer ring 11 facing the rear end face of the sensor holder 9 may be designed in a corrugated shape, a triangular zigzag shape, a square zigzag shape, or the like.

Also, in the embodiment shown in fig. 9, the buffer ring 11 may be designed as a complete continuous annular ring. Alternatively, the buffer ring 11 may be designed into a discrete ring shape, i.e. the buffer ring 11 may comprise short arc segments which are uniformly distributed or non-uniformly distributed along the circumferential direction and have equal or unequal arc lengths.

Under the principles of the present application, those skilled in the art can make various adaptive designs for the cushion ring 11 according to the specific structure and operation characteristics of the master cylinder.

According to the brake master cylinder disclosed by the application, the elastic buffer ring is arranged between the sensor frame at the rear end of the first piston and the end wall of the adapter, and after a driver releases the brake pedal quickly, the buffer ring can buffer the impact of the sensor frame on the adapter when the first piston is reset backwards under the action of the first spring, so that impact noise and vibration are reduced or even eliminated, and good driving feeling can be provided for the driver.

Although the application is described herein with reference to specific illustrative embodiments, the scope of the application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the application.

Claims

1. A master cylinder comprising:

A cylinder (1);

A first piston (2) the front of which is axially slidably inserted into the cylinder;

A second piston (3) slidably arranged in the cylinder;

A first spring (4) arranged in an axially compressed manner between the first piston and the second piston;

a second spring (5) arranged to apply a rearward axial thrust to the second piston;

An adapter (6) fixed to the rear end of the cylinder, comprising a cylindrical body (6 a) and a radially inwardly extending end wall (6 c) at the rear end of the body, the rear portion of the first piston being exposed from the rear end of the cylinder and being located within the adapter;

A sensor holder (9) fixed to the rear end of the first piston, facing the end wall of the adapter, configured to hold a magnet of the brake pedal travel sensor;

the brake master cylinder is characterized by further comprising:

And an elastic buffer ring (11) which is arranged in a pit formed on the rear end surface of the sensor frame or the end wall of the adapter and is axially compressed between the rear end surface of the sensor frame and the end wall of the adapter under the thrust of the first spring under the static state of the brake master cylinder.

2. The master cylinder of claim 1, wherein the buffer ring has a cross-sectional dimension of an exposed portion exposed from the recess that is smaller than a cross-sectional dimension of an embedded portion embedded in the recess in a natural state in which the buffer ring is not axially compressed.

3. The master cylinder of claim 1, wherein the buffer ring has a cross-section of a portion exposed from the recess in a natural state in which the buffer ring is not axially compressed, which is trapezoidal, partially circular, or partially elliptical.

4. The master cylinder of claim 1, wherein the buffer ring has an exposed portion exposed from the recess in a natural state in which the buffer ring is not axially compressed, the exposed portion being of a reduced amount of material relative to an embedded portion embedded in the recess.

5. The master cylinder of claim 4, wherein a side of the buffer ring facing away from the pit is corrugated or zigzag.

6. The brake master cylinder of any one of claims 1-5, wherein the buffer ring is a continuous annular shape or a discrete annular shape.

7. The brake master cylinder according to any one of claims 1 to 5, wherein the buffer ring is composed of a plurality of circular arc segments that are discrete in a circumferential direction.

8. The brake master cylinder according to any one of claims 1 to 5, wherein the amount of variation in the static thickness of the cushion ring in a static state of the brake master cylinder is within an allowable tolerance of a brake pedal stroke sensor, and an outer diameter of the cushion ring is smaller than an outer diameter of a sensor holder.

9. The master cylinder of claim 8, wherein the buffer ring has a static thickness equal to or greater than a pit depth.

10. The brake master cylinder of any one of claims 1-5, wherein the cushion ring is made of an elastomeric material.