KR20020007614A - Brake booster - Google Patents

Abstract

PURPOSE: A brake booster of a vehicle is provided to check a brake pedal at jump-in step increasing output suddenly, and to improve performance of the brake booster by transmitting reaction force to the brake pedal before eliminating clearance by a reaction disk with forming a wedged end of a plunger near the reaction disk. CONSTITUTION: A brake booster for a vehicle is composed of a diaphragm(31) dividing a case; a cylindrical valve(60) having a hollow installed in the diaphragm; a plunger(70) moving back and forth in the hollow of the valve; an input shaft(40) connected to the rear end of the plunger; a reaction disk(51); and an output shaft(50) installed in the end of the plunger. The wedged end of the plunger is formed near the reaction disk. The output is transmitted through the output shaft to a master cylinder assembly with pushing front and rear diaphragms, front and rear power pistons and the valve body for the output shaft. The reaction disk is contacted to the wedged end of the plunger in increasing output drastically at constant input. Sudden braking or wrong operation is reduced with checking the brake by transmitting reaction force to the brake pedal. Braking pressure from the brake pedal is transmitted to the output shaft with contacting the input shaft to the output shaft in putting on the brake.

Description

Automotive brake booster

The present invention relates to a vehicle brake booster, and more particularly, to a vehicle brake booster with improved flanger front end surface.

In general, a brake booster for a vehicle (BRAKE BOOSTER) is a device that generates a large braking force with a small force by using a pressure difference between the vacuum and the atmosphere, the master cylinder assembly is coupled to the front plate to form a braking hydraulic pressure through the amplified force .

As shown in FIG. 1, a conventional brake booster for a vehicle includes a casing 1 in which the front plate 1a and the rear plate 1b are hermetically coupled to each other, and the inside of the casing 1 with the front chambers 2a and 2b. The center plate 1c partitioned into 2C of rear chambers is provided.

The center plate 1c is provided so that the valve body 6 slides freely through the center of the center plate 1c and moves to the front chambers 2a, 2b and the rear chambers 2c, 2d. It is provided to control.

In addition, the input shaft 4 is provided to operate the valve body 6 according to the operation of the brake pedal (not shown), and the output shaft 5 receiving the force applied on the same axis as the input shaft 4 has the valve body. It is provided via the reaction disk 5a of elastic material (rubber) located in the center part of (6).

On the other hand, the front chambers 2a and 2b are formed in the space between the front plate 1a and the center plate 1c, which are again formed by the front diaphragm 3a and the front power piston 3b. It is divided into 2a and the front transformer chamber 2b, and the return spring 8 which restores the valve main body 6 is provided in the front positive pressure chamber 2a.

In addition, the rear chambers 2C and 2d are formed in the space between the center plate 1c and the rear plate 1b, which are also vacuumed by the rear diaphragm 3c and the rear power piston 3d. It is divided into the positive pressure chamber 2c and the rear transformer chamber 2d in which the pressure changes.

The valve body 6 has a cylindrical shape having a plurality of outer peripheries, one end of which has a front diaphragm 3a, a front power piston 3b, a center plate 1c, a rear diaphragm 3c and a rear power. It is fitted to the center of the piston (3d) is coupled, the other end is provided with an air suction portion (6c) hollow inside and communicates with the outside air through the center of the rear plate (1b).

In addition, in the valve main body 6, a transformer passage 6a for communicating the constant pressure chambers 2a, 2c and the transformer chambers 2b, 2d, and the transformer chamber 2b, 2d with the outside air ( 6b),

In addition, the valve body 6 is provided with a plunger 7 sliding in the axial direction in association with the end of the input shaft 4, and an input shaft 4 inside the valve body 6, that is, inside the air suction part 6c. The poppet valve 6d of elastic material is installed to substantially control the air inflow by the operation of.

The poppet valve 6d has a rear end fixed to the inner circumference of the air intake part 6c so as to function as a vacuum valve and an air valve, and the front end is configured as a free end.

Next, the operation of the conventional vehicle brake booster configured as described above will be described.

First, when the driver does not press the brake pedal, each of the positive pressure chambers 2a and 2c and the transformer chambers 2b and 2d is maintained in a vacuum state by a negative pressure source (not shown). When the driver presses the brake pedal a little in this state, the input shaft 4 moves forward and the valve body 6 moves slightly toward the reaction disk 5a together with the plunger 7.

Accordingly, the transformer passage 6b communicates with the outside air, and the external air flows into the transformer chambers 2b and 2d through the transformer passage 6b. The external air is instantaneously introduced by the differential pressure, so that the diaphragms 3a, 3c, the power pistons 3b, 3d, and the valve body 6 are pushed toward the positive pressure chamber 2a, 2c, and amplified more than the input. The output is transmitted to the master cylinder assembly (not shown) through the reaction disk 5a and the output shaft 5 to generate braking hydraulic pressure.

At this time, the clearance G1 between the reaction disk 5a and the front end face of the plunger 7 is maintained, and the output at this time is suddenly increased without increasing the input force.

This jump-in effect is called a jump-in effect, in which the reaction disc 5a is deformed by stepping deeply on the brake pedal, whereby the reaction disc 5a fills the clearance G1 with the plunger 7 tip. Until it continues. Therefore, the clearance G1 space between the reaction disk 5a and the tip of the plunger 7 is called a jump-in space.

The above jump-in effect is an important characteristic of the brake booster, which is very important when designing a brake booster having a high power ratio, and in order to have a high power ratio, it is preferable to design a jump-in space in a wide range.

However, reaction force from the output shaft is not transmitted to the brake pedal while the reaction disk is in the jump-in step. Therefore, the reaction force does not occur in the driver's position, which is not known as the jump-in section, so even when the user presses the brake pedal, the brake is completely turned off, and information on whether the brake is applied cannot be obtained. Therefore, there is a possibility that the brakes will not work properly and will cause a sudden braking by stepping deeper on the brake pedal.

Therefore, when designing the brake booster, the designer should design such that it does not feel completely shut off, so there is a limit to increase the jump-in space, and accordingly, there is a limit to increase the power ratio of the brake booster.

The present invention is to solve this problem, the object of the present invention is to improve the tip surface of the flanger toward the reaction disk side to increase the jump-in space so that the driver does not feel the brake pedal does not work By increasing the jump-in space, it is possible to manufacture a brake booster with a high power ratio.

1 is a cross-sectional view of a conventional vehicle brake booster.

2 is a cross-sectional view of a vehicle brake booster according to the present invention.

3 is a force characteristic graph of the brake booster according to the present invention.

Figures 4a, 4b, 4c shows the operating state in the jump-in step of the brake booster according to the present invention.

Explanation of symbols on the main parts of the drawings

10: casing, 40: input shaft,

50: output shaft, 51: reaction disc,

60: valve body, 64: poppet valve,

66: cylinder portion, 67: recess portion,

70: plunger.

In order to achieve the above object, a vehicle brake booster according to the present invention includes a diaphragm for dividing a case into a constant pressure chamber and a transformer chamber; A cylindrical valve installed in the diaphragm and having a hollow provided therein to communicate with the atmosphere; A plunger installed in the hollow portion of the valve so as to move forward and backward; An input shaft connected to a rear end of the plunger; An output shaft provided at a distal end of the plunger with a reaction disk interposed therebetween,

The plunger front end surface of the reaction disk side is provided in a wedge shape.

Hereinafter, with reference to the accompanying drawings a preferred embodiment according to the present invention will be described in detail.

As shown in FIG. 2, the brake booster for a vehicle according to the present invention may include a casing 10 in which the front plate 11 and the rear plate 12 are hermetically coupled to each other, and the interior of the casing 10 with a front seal 21 and 22. ) And a center plate 13 partitioned into rear chambers 23 and 24.

The center plate 13 is provided with a valve body 60 so as to slide freely through the center of the center plate 13 to allow air to flow into the front chambers 21 and 22 and the rear chambers 23 and 24. It is provided to control.

In addition, the input shaft 40 is provided to operate the valve body 60 according to the operation of the brake pedal (not shown), the output shaft 50 receives the force applied on the same axis as the input shaft 40 is the valve body It is provided through the reaction disk 51 of an elastic material (rubber) located in the center of the (60).

On the other hand, the front chambers 21 and 22 are formed in the space between the front plate 11 and the center plate 13, which are again formed by the front diaphragm 31 and the front power piston 32. It is divided into 21 and the front transformer chamber 22.

The front positive pressure chamber 21 is provided with a return spring 14 for restoring the valve body 60, and the front plate 11 wall is provided for communicating with the vacuum pump so that the front positive pressure chamber 21 is always kept in a vacuum state. The vacuum connection tube 15 is mounted.

Further, the rear chambers 23 and 24 are formed in the space between the center plate 13 and the rear plate 12, which are also vacuumed by the rear diaphragm 33 and the rear power piston 34. It is divided into the positive pressure chamber 23 and the rear transformer chamber 24 in which pressure changes.

The valve body 60 is provided in a cylindrical shape having a plurality of outer peripheries, one end of which has a front diaphragm 31, a front power piston 32, a center plate 13, a rear diaphragm 33, and a rear power. It is fitted in the center of the piston (34), the other end is provided with an air suction portion (63) hollow inside and communicates with the outside air through the center of the rear plate (12).

In addition, the valve main body 60 has a constant pressure passage 61 for communicating the constant pressure chambers 21, 23 and the transformer chambers 22, 24, and a transformer passage for communicating the outside air with the transformer chambers 22, 24. 62) and a cylinder portion 66 is formed in the central portion in the axial direction.

The cylinder portion 66 is provided with a plunger 70 which slides in the axial direction in association with the end of the input shaft 40, and operates the input shaft 40 inside the valve body 60, that is, the inner circumference of the air suction portion 63. By the poppet valve 64 of the elastic material which substantially controls the air inlet is installed.

The poppet valve 64 has a rear end fixed to the inner circumference of the air suction unit 63 and has a free end. In addition, the first valve seat portion 65 is provided on the inner circumference of the valve body 60 to perform the vacuum valve function in combination with the poppet valve 64, so that the tip of the poppet valve 64 has the first valve seat portion 65. When seated in the static pressure passage 61 is closed. In addition, a second valve seat 71 is provided at the rear end of the plunger 70 so as to perform an air valve function in combination with the poppet valve 64, so that the tip of the poppet valve 64 is second valve seat 71. When seated in the outside air is blocked to flow into the transformer chamber (22, 24).

Further, according to the present invention, the front end surface of the plunger 70 on the reaction disk 51 side is formed in a wedge shape so that reaction force can be transmitted to the brake pedal (not shown) even in the jump-in section.

Next, the operation and effect of the brake booster for a vehicle according to the present invention configured as described above will be described with reference to FIGS. 2, 3 and 4A, 4B, and 4C.

In a vehicle equipped with a vehicle brake booster according to the present invention, when the driver slightly presses a brake pedal (not shown) and the input shaft 40 moves forward in the direction of the arrow Y, the plunger 70 is slightly pushed toward the reaction disc 51. As a result, the second valve seat 71 is separated from the tip of the poppet valve 64 so that the communication between the positive pressure chambers 21 and 23 and the transformer chambers 22 and 24 is interrupted, and the external air is moved by an air pressure difference. Direction, that is, through the air suction part 63 and the transformer passage 62, it flows into each transformer chamber 22 and 24 in a vacuum state.

The front diaphragm 31 and the front power piston 32 and the rear diaphragm 33 and the rear power piston 34 which are actuated accordingly are pushed to the output shaft 50 together with the valve body 60, so that the output is output shaft. It is transmitted to the master cylinder assembly (not shown) through 50 to generate a braking pressure. At this time, the output increases dramatically even though the input through the input shaft 40 is substantially the same.

This phenomenon is commonly referred to as a jump-in (JUMP IN) effect. Initially, as shown in FIG. 4A, a clearance G2 between the end of the plunger 70 and the reaction disk 51 according to the present invention exists. It shows the same power characteristic (Section A) as before.

However, according to the present invention, since the reaction disc side end face of the plunger 70 is provided in a wedge shape, the reaction disc 51 is a wedge-type plunger 70 as shown in FIG. 4B during the jump-in. The end of section A is terminated early and proceeds to section A '.

In section A ', the output shaft 50 and the input shaft 40 are partially connected through the reaction disk 51 and the plunger 70, so that reaction force is transmitted to some input shaft 40 and transmitted to the brake pedal (not shown). . Therefore, the reaction force transmitted to the brake pedal (not shown) allows the driver to check the operating state of the brake, thereby reducing the possibility of malfunction such as sudden braking.

When the brake pedal (not shown) is further deepened in the section A ', as shown in FIG. 4C, when the jump-in space is completely filled by the reaction disk 51, the boost effect by the brake booster disappears. Since the input shaft 40 and the output shaft 50 come into contact with each other through the reaction disc 51 and the plunger 70, the driver presses a brake pedal (not shown) to the section B where the force is transmitted to the output shaft 50 as it is. The jump-in step ends.

As described in detail above, the vehicle brake booster according to the present invention is provided with a reaction disc side end surface of the plunger in a wedge shape so that reaction force is transmitted to the brake pedal before the reaction disc completely fills the jump-in space. The driver can check the state of the brake pedal even in the jump-in phase, and accordingly, it is possible to manufacture a brake booster having a high power ratio.

Claims (1)

A diaphragm dividing the case into a constant pressure chamber and a transformer chamber; A cylindrical valve installed in the diaphragm and having a hollow provided therein to communicate with the atmosphere; A plunger installed in the hollow portion of the valve so as to move forward and backward; An input shaft connected to a rear end of the plunger; In a vehicle brake booster having an output shaft provided with a reaction disk interposed between the front end of the plunger, The front end surface of the plunger on the side of the reaction disk is provided with a wedge-shaped vehicle brake booster.