KR101315778B1 - Brake booster for vehicle - Google Patents

Abstract

The present invention relates to a vehicle brake booster capable of changing the area in contact with the reaction disk to prevent the dispersion of jump-in values.
The vehicle brake booster according to the present invention is a vehicle brake booster that generates a large braking force with a small force by using a pressure difference between vacuum and atmosphere, and is installed in a cylinder formed inside the valve body so that the rear end portion can be brake pedaled. By contacting the plunger installed on the input shaft moving forward and backward in the axial direction and maintaining a predetermined clearance with the reaction disk provided at the tip end of the output shaft, thereby adjusting the area in contact with the reaction disk to increase the power ratio and jump-in. An adjustment member for facilitating adjustment of the generation timing, the adjustment member comprising: a reaction rod having a predetermined length and moving forward and backward with the plunger; A bush having a center penetrated so that the front end of the reaction rod is inserted; A first spring retainer supporting the reaction rod and the bush and slidably disposed outside the reaction rod; A second spring retainer fixed to the rear of the reaction rod; And a control spring interposed between the first and second spring retainers.

Description

Brake booster for vehicle

The present invention relates to a vehicle brake booster, and more particularly to a vehicle brake booster that can change the area in contact with the reaction disk to prevent the dispersion of jump-in value.

In general, 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. 1 and 2 show such a conventional vehicle brake booster.

1 and 2, the vehicle brake booster includes a casing 1 in which the front cell 1a and the rear cell 1b are hermetically coupled to each other, and the inside of the casing 1 includes a positive pressure chamber 2a and a transformer chamber. 2b) the diaphragm (3a) and the power piston (3b), one end is combined with the diaphragm (3a) and power piston (3b) and the other end penetrates the rear cell (1b) to control the air inlet ( 6), an input shaft 4 interlocked by a brake pedal (not shown), and an output shaft 7 that receives a force of displacement according to its operation. At this time, a master cylinder assembly (not shown) is coupled to the front cell 1a so that braking hydraulic pressure is formed through the amplified force.

The valve body 6 slides integrally with the diaphragm 3a and the power piston 3b. To this end, the diaphragm 3a and the power piston 3b are coupled to one end of the valve body 6, and the other end thereof. The air suction part 6a which penetrates the center part of the rear cell 1b and communicates with the atmosphere is provided.

In addition, the valve body 6 is provided with a positive pressure passage 6b for communicating the positive pressure chamber 2a and the transformer chamber 2b, and a transformer passage 6c for communicating the atmosphere and the transformer chamber 2b. (4) The plunger 5 which is coupled to the end and slides in the axial direction and the poppet valve 6d which controls the inflow of air in accordance with the operation of the input shaft 4 are arranged. And the rear end of the output shaft 7 is fitted with a disk-shaped reaction disk (7a) for doubling the force acting due to the cross-sectional area to transfer to the output shaft (7). The reaction disk 7a is made of an elastic material and is in contact with the center of the front end face of one end of the valve body 6.

The rear end of the poppet valve 6d is firmly fixed to the air intake part 6a of the valve body 6 through the fixing member 6e, and the tip thereof is transformed into the positive pressure passage 6b by the operation of the input shaft 4. The passage 6c is selectively opened and closed. The first valve seat 6f is provided on the inner circumference of the valve body 6 corresponding to the front end of the poppet valve 6d, and performs a vacuum valve function by the mutual combination thereof. In addition, the second valve seat 5a is formed at the rear end of the plunger 5 to perform the air valve function in combination with the front end of the poppet valve 6d, thereby controlling the inflow of external air. That is, when the tip of the poppet valve 6d is seated on the first valve seat 6f, the positive pressure passage 6b is closed, and when the seat of the poppet valve 6d is seated on the second valve seat 5a, the transformer passage 6c is closed and the transformer chamber 2b is closed. ) Is blocking the inflow of air.

In addition, first and second springs 6g and 6h are provided in the air suction portion 6a of the valve body 6. The double first spring 6g supports between the fixing member 6e and the input shaft 4 to return the input shaft 4 to the rear side when the brake is released, and the second spring 6h moves the poppet valve 6d to the first position. And elastically support the second valve seats 6f and 5a.

On the other hand, the cylinder 6i is formed in the direction of the central axis of the valve body 6, and the cylinder 6i is provided with an adjusting member 8 for adjusting the power ratio. The front end of the adjusting member 8 and the reaction disk 7a are arranged so that a predetermined clearance G1 is normally maintained.

The adjustment member 8 reacts through a spring retainer 8a fixed to the tip of the plunger 5, a reaction plunger 8b facing the spring retainer 8a and spaced apart at regular intervals, and through the spring retainer 8a. A pin 8c inserted into the plunger 8b and a control spring 8d interposed between the spring retainer 8a and the reaction plunger 8b. At this time, a predetermined clearance G1 is formed between the tip of the reaction plunger 8b and the reaction disk 7a. The operation of the adjustment member 8 will be described again below.

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

First, when the driver does not step on the brake pedal (not shown), the positive pressure chamber 2a and the transformer chamber 2b are kept in a vacuum state at the 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 main body 6 is slightly moved toward the reaction disk 7a together with the plunger 5.

As a result, the transformer passage 6c communicates with the atmosphere, so that external air flows into each transformer chamber 2b through the transformer passage 6c. The flowed air is instantaneously introduced by the differential pressure, so that the diaphragm 3a, the power piston 3b, and the valve body 6 are pushed toward the positive pressure chamber 2a, and the output amplified from the input is reacted with the reaction disk 7a and the output shaft. It is delivered to the master cylinder assembly (not shown) through (7) to generate the braking hydraulic pressure.

Until this time, the clearance G1 between the reaction disc 7a and the front end face of the reaction plunger 8b of the adjusting member 8 is maintained, and the output is suddenly increased without an increase in the input force. -in) called effect. The jump-in effect is generated until the brake pedal is gradually pressed down so that the reaction disk 7a is deformed and the clearance G1 with the tip of the reaction plunger 8b, i.e., fills the empty space. Therefore, the clearance G1 between the reaction disk 7a and the tip of the plunger 8b is called a jump-in space. This jump-in effect is an important feature of the brake booster and is essential for immediate braking action when the brake pedal is activated.

Subsequently, when the brake pedal is pressed more deeply, the control spring 8d interposed between the reaction plunger 8b and the spring retainer 8a is compressed, and the reaction plunger 8b is brought to the reaction disc 7a side by the elastic force. Pushed At this time, the reaction disk 7a acts simultaneously with the force transmitted from the reaction plunger 8b and the force transmitted from the valve body 6, and the ratio of the force directly applied by the driver and the force formed by the pressure difference is the reaction disk. It is determined by the area ratio of the tip contact surface of the valve body 6 which contacts 7a and directly exerts a pressure, and the tip end surface of the reaction plunger 8b.

On the other hand, when the reaction plunger 8b comes into contact with the reaction disk 7a, that is, when the empty space constituting the clearance G1 is filled, the reaction force of the output shaft 7 passes through the reaction disk 7a and the adjusting member 8. It is transmitted to the input shaft 4.

However, the conventional brake booster has a structure using an additional jump-in by the control spring 8d when the second boost ratio is generated after the primary boost ratio is generated, that is, the input applied through the brake pedal and the output obtained by the pressure difference. As described above, the ratio of is determined by the ratio of the tip area of the reaction plunger 8d directly in contact with the reaction disk 7a and the contact area ratio of the valve body 6. In the conventional booster, the area of the component that determines the power ratio is set. As the load and ratio of the control spring (8d) are used, the dispersion is greatly generated, and the control spring (8d) must be designed in a limited space so that there is a limit to have a secondary power ratio compared to the primary power ratio. There is a problem. Thus, there is a problem that the unit cost of the product is increased by adding a processing process or a management process to reduce the dispersion.

The present invention has been made to solve the above problems, and an object thereof is to provide a brake booster for a vehicle that can easily adjust the power ratio by changing the area in contact with the reaction disk and divided into two.

In order to achieve the above object, the vehicle brake booster of the present invention is a vehicle brake booster that generates a large braking force with a small force by using a pressure difference between the vacuum and the atmosphere, and is capable of moving forward and backward in a cylinder formed inside the valve body. The rear end portion is in contact with the plunger installed on the input shaft which moves forward and backward in the axial direction by the brake pedal, and the front end portion maintains a predetermined clearance with the reaction disk installed on the output shaft. A control member for facilitating adjustment of a jump-in generation time, the control member comprising: a reaction rod having a predetermined length and moving forward and backward with the plunger; A bush having a center penetrated so that the front end of the reaction rod is inserted; A first spring retainer supporting the reaction rod and the bush and slidably disposed outside the reaction rod; A second spring retainer fixed to the rear of the reaction rod; And a control spring interposed between the first and second spring retainers.

Preferably, the front end surface of the bush is installed to maintain the same surface as the front end surface of the reaction rod during initial brake operation.

Preferably, the front end of the valve body in contact with the reaction disk is provided with an annular portion extending radially larger than the diameter of the cylinder, the diameter of the bush is made to correspond to the diameter of the annular portion bushing is fitted into the annular portion do.

Preferably, the outer circumferential surface of the reaction rod is formed with a first step portion having a reduced diameter, and the through-hole penetrating the center of the bush is formed with a second stepped portion extending in the radial direction, when the reaction rod is coupled to the bush. The stepped surfaces of the first stepped portion and the second stepped portion are made to maintain the same surface with each other.

Preferably, the first spring retainer is installed to be in contact with the step surface of the first step portion and the second step portion.

According to the brake booster for a vehicle according to the present invention, when the driver presses the brake pedal more than a predetermined level by adjusting the area of the bush and the reaction rod in contact with the reaction disc, the bush is returned from the reaction rod by the reaction force to react with the reaction rod. By pressing the reaction disk, a larger power ratio (secondary jump-in effect) is formed than in the initial power range. That is, the power ratio can be easily adjusted according to the change of the area of the bush and the reaction rod, as well as the dispersion due to the jump-in space, and the freedom of design can be improved.

In addition, the timing of the second power generation ratio can be adjusted only by the load management of the control spring, thereby reducing the cost of the product.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described in detail with reference to the following drawings, which illustrate preferred embodiments of the present invention, and thus the technical idea of the present invention should not be construed as being limited thereto.
1 is a cross-sectional view showing a conventional vehicle brake booster.
2 is a partially enlarged view of FIG. 1;
3 is a cross-sectional view showing a vehicle brake booster according to a preferred embodiment of the present invention.
4 is a partially enlarged view of FIG. 3.
5 and 6 are views showing the operating state of the vehicle brake booster according to a preferred embodiment of the present invention.
7 is a graph showing the power-up characteristic of the brake booster for a vehicle according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

3 is a cross-sectional view illustrating a brake booster for a vehicle according to an exemplary embodiment of the present invention.

Referring to the drawings, the brake booster for a vehicle according to the present embodiment includes a casing 10 in which the front shell 11 and the rear shell 12 are hermetically coupled, and the inside of the casing 10 with the positive pressure chamber 20 at the front and the rear with the casing 10. The diaphragm 41 and the power piston 42 which are divided into the transformer chamber 30 of the pump, and the central portion of the diaphragm 41 and the power piston 42 to slide freely to move, the pressure chamber 20 and the transformer The valve body 50 for controlling the air inflow into the chamber 30, the input shaft 60 for operating the valve body 50 by the operation of the brake pedal (not shown), and to receive the doubled force by the differential pressure An output shaft 80 disposed coaxially with the input shaft 60 and provided with a reaction disk 81 is provided.

In addition, a return spring 13 for restoring the valve body 50 is installed in the constant pressure chamber 20, and a vacuum for communicating with a vacuum source so that the constant pressure chamber 20 is always maintained in a vacuum state on the wall of the front cell 11. The connecting pipe 14 is mounted.

The valve body 50 has a multi-stage stepped cylindrical shape, one end of which is fitted to the center of the diaphragm 41 and the power piston 42 is coupled. The other end of the valve body 50 passes through the center of the rear shell 12 to form an air suction unit 51 communicating with the external atmosphere. The input shaft 60 is located at the center of the air intake unit 51.

In addition, the valve body 50 has a positive pressure passage 52 provided to communicate the constant pressure chamber 20 and the transformer chamber 30, and a transformer passage 53 provided to communicate the transformer chamber 30 with the atmosphere. One end of the cylinder 54 is provided in the axial direction. The cylinder 54 is provided with a plunger 70 in such a manner as to be retractable so as to slide in the axial direction in association with the tip of the input shaft 60, and the input shaft 60 is formed inside the valve body 50, that is, inside the air suction unit 51. The poppet valve 55 is formed of an elastic material to substantially control the air inflow by the operation of.

The positive pressure passage 52 communicates the positive pressure chamber 20 and the transformer chamber 30 in an open state, and the pressure passage 53 opens the air suction part 51 and the transformer chamber 30 in an open state. To communicate with. In addition, the plunger 70 is moved forward by the input shaft 60 when braking, and the input shaft 60 which has been moved forward returns to the rear side through the elastic restoring force of the first spring 56 when the brake is released. The first spring 56 is formed in a truncated cone shape, and the rear end of the first spring 56 is supported around the outer surface of the input shaft 60 on which the step is formed, and the front end is supported by the fixing member 58 that fixes the poppet valve 55.

The poppet valve 55 is provided in a ring shape through an elastic material so as to be able to move forward and backward along the longitudinal direction of the input shaft 60. The poppet valve 55 has a rear end firmly fixed to the inner circumference of the air suction unit 51 of the valve body 50 through the fixing member 58, and the front end of the poppet valve 55 is operated along the operation of the input shaft 60. And the transformer passage 53 is selectively opened and closed.

In order to perform a vacuum valve function in combination with the poppet valve 55, a first valve seat 59 is provided on the inner circumference of the valve body 50 so that the tip of the poppet valve 55 is seated on the first valve seat 59. The positive pressure passage 52 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 55, so that the tip of the poppet valve 55 is connected to the second valve seat 71. When seated, the outside air is blocked from flowing into the transformer chamber 30. At this time, the poppet valve 55 is elastically supported toward the first and second valve seats 59 and 71 through the second spring 57 installed at the rear.

On the other hand, the vehicle brake booster according to the present embodiment is provided with a control member 100 is configured to change the area in contact with the reaction disk 81 and the reaction disk 81 and the predetermined clearance (G2) is normally.

The adjustment member 100 serves to facilitate the adjustment of the power ratio and the jump-in generation time by adjusting the area in contact with the reaction disk 81, the detailed structure thereof Figure 3 Referring to the following.

According to the invention, the adjusting member 100 is provided between the reaction disk 81 and the plunger 70 is disposed in the cylinder 54 of the valve body 50. More specifically, the adjustment member 100 has a predetermined length and the reaction rod 110 to move forward and backward with the plunger 70, the bush 120 through the center so that the front end of the reaction rod 110 is inserted, A first spring retainer 131 which supports the reaction rod 110 and the bush 120 and is slidably provided on the outside of the reaction rod 110, and a second spring retainer 132 fixed to the rear of the reaction rod 110. And a control spring 140 interposed between the first and second spring retainers 131 and 132.

In this case, an annular portion 54a extended radially larger than the diameter of the cylinder 54 may be formed at the front end of the valve body 50 in contact with the reaction disk 81. Accordingly, the diameter of the bush 120 is made to correspond to the diameter of the annular portion (54a) is coupled to the bush 120 is fitted to the annular portion (54a). The formation of the annular portion 54a and the diameter of the annular portion 54a are for adjusting the power ratio by changing the diameter A2 of the bush 120. Similarly, the power ratio can be adjusted by changing the diameter A3 of the reaction rod 110 inserted through the bush 120.

In order to set the jump-in value within a specific range, the bush 120 has a diameter A2 smaller than the diameter A1 of the reaction disk 81 and larger than the diameter A3 of the reaction rod 110, and the brake booster In the initial state of the so that the front end surface of the bush 120 is located on the same line as the front end surface of the reaction rod 110. Then, the disc-shaped reaction disk 81 having a predetermined thickness is seated on the rear end of the output shaft 80 such that the rear surface is in surface contact with one end surface of the valve body 50. That is, a predetermined clearance G2 is maintained between the center of the rear surface of the reaction disk 81 and the tip of the adjusting member 100.

On the other hand, the first spring retainer 131 is interposed between the reaction rod 110 and the bush 120 to provide an elastic force of the control spring 140, it is provided to be able to slide outside the reaction rod 110. . Accordingly, the first stepped portion 111 having a reduced diameter is formed on the outer circumferential surface of the reaction rod 110, and the second stepped portion 121 extending in the radial direction is formed in the through hole passing through the center of the bush 120. Is formed. That is, when the reaction rod 110 is coupled to the bush 120, the stepped surfaces of the first stepped part 111 and the second stepped part 121 maintain the same plane. That is, as shown, the first spring retainer 131 is installed to contact the step surface of the first step portion 111 and the second step portion 121.

Such a structure is to change the area in contact with the reaction disk 81 by adjusting the operation of the reaction rod 110 and the bush 120 when forming the power ratio. The operation of the adjustment member 100 will be described in detail in the operation description of the vehicle brake booster below.

Next, an operation state of the vehicle brake booster according to the present invention will be described with reference to FIGS. 5 to 7.

First, as shown in FIG. 5, when the driver steps on the brake pedal slightly (not shown) in the vehicle equipped with the vehicle brake booster according to the present invention, the input shaft 60 moves in the direction of the arrow Y, the plunger 70 and As the adjusting member 100 is slightly pushed toward the reaction disk 81 side, the second valve seat 71 is separated from the tip of the poppet valve 55 so that the communication between the positive pressure chamber 20 and the transformer chamber 30 is blocked and at the same time, The air flows into each of the vacuum chambers 30 in the vacuum state through the direction of the arrow, that is, through the air suction unit 51 and the transformer passage 53.

Thus, as the operable diaphragm 41 and the power piston 42 are pushed together with the valve body 50 toward the output shaft 80, the output is transmitted to the master cylinder assembly (not shown) through the output shaft 80 to provide a braking pressure. Generate. At this time, the output increases dramatically even though the input through the input shaft 60 is substantially the same.

This phenomenon is commonly referred to as a jump-in (JUMP IN) effect (BR0 section in FIG. 7), and the rear of the reaction disk 81 and the adjusting member 100, that is, the line of the bush 120 and the reaction rod 110 The clearance G2 with the cross section still exists, so that the reaction force of the reaction disk 81 is not transmitted to the input shaft 60 side.

Further, when the brake pedal is further pressed, the output and reaction force of the reaction disk 81 gradually increase, whereby the rear surface of the reaction disk 81 and the front end surface of the adjustment member 100 come into contact with each other, and the reaction disk 81 A portion of the reaction force is transmitted to the input shaft 60 through the adjusting member 100 and the plunger 70.

At this time, the reaction force 81 and the force transmitted from the center of the valve body 50 acts on the reaction disk 81 at the same time. Therefore, the ratio of the force applied by the driver and the force amplified by the pressure difference is represented by the ratio of the area of the tip of the adjusting member 100 to the area of the central portion of one end of the valve body 50 that contacts and applies the pressure to the reaction disk 81. Can be. That is, the initial booster power ratio is the BR1 section in FIG. 7, and the booster power ratio of this section is the diameter of the reaction disk 81 to A1 and the adjustment member 100, that is, the bush 120 (or the diameter of the annular portion). When the diameter is A2, it is expressed as follows.

BR1 = A1 / A2

Subsequently, as shown in FIG. 6, when the brake pedal is pressed deeper and the force of the input shaft 60 exceeds a predetermined value, the pressure difference between the positive pressure chamber 20 and the transformer chamber 30 becomes larger, and the reaction disc is further increased. As the pressure acting on the 81 increases, the clearance G2, that is, the jump-in space is filled by the elastic deformation of the reaction disk 81 and the pressing of the adjustment member 100. In this case, the bush 120 and the reaction rod 110 supported by the first spring retainer 131 during the operation of the initial adjustment member 100 are moved together with the elastic force of the control spring 140 to move the input shaft 60. When the force exceeds a predetermined value, i.e., when the output load is greater than the load of the control spring 140, the bush 120 compresses the control spring 140 and is returned from the reaction rod 110 by the reaction force. That is, only the reaction rod 110 is configured to press the reaction disk 81 together with the input shaft 60 and the plunger 70.

Accordingly, a second jump-in effect occurs in which the power ratio increases sharply rather than the initial stage (BR2 section in FIG. 7), and the BR2 section has a rear surface of the reaction disk 81 as the input force increases. It is in close contact with the leading edge of the and continues until the jump-in space is completely filled. As such, when the force of the input shaft 60 exceeds a predetermined value, the booster power ratio is the BR2 section in FIG. 7, and the booster power ratio of this section is expressed as follows.

BR2 = A1 / A3

On the other hand, when the brake pedal is pressed deeper and the input reaches the point P (see FIG. 7), the reaction force of the reaction disk 81 no longer affects, and instead, the adjustment member 100 and the reaction disk 81 are fitted. Reach and exert any effect. Therefore, in this case, the driving force effect by the driver's stepping on the brake pedal is lost, and the driving force is formed by the driver's stepping on the brake pedal as it is, which is the BR3 section.

When the driver releases the brake pedal, the adjusting member 100, the plunger 70, and the input shaft 60 are restored by the return spring 13 installed in the positive pressure chamber 20, and at the same time, the poppet valve 55. Is pushed by the second valve seat 71 is separated from the first valve seat 59, and serves as an air valve to prevent the inflow of air.

In addition, as the poppet valve 55 is separated from the first valve seat 59, the positive pressure passage 52 communicates with each other, so that the air in the transformer chamber 30 is discharged into the vacuum constant pressure chamber 20, and the positive pressure continues. The chamber 20 is vacuumed by the negative pressure source, and becomes the initial state of the brake booster.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

10 casing 20 static pressure chamber
30: transformer chamber 41: diaphragm
42: power piston 50: valve body
54 cylinder 54a annular part
60: input shaft 70: plunger
80: output shaft 81: reaction disc
100: adjusting member 110; Reaction Load
120: bush 131: first spring retainer
132: second spring retainer 140: control spring

Claims (5)

In a brake booster for a vehicle that generates a large braking force with a small force by using a pressure difference between the vacuum and the atmosphere,
The reaction disc is formed in the cylinder formed inside the valve body so as to be capable of moving forward and backward, and the rear end is in contact with the plunger installed at the input shaft axially moving forward and backward by the brake pedal, and the front end is maintained with the reaction disk provided at the output shaft and a predetermined clearance. It is provided with a control member for adjusting the area in contact with the and facilitates the adjustment of the power ratio and the jump-in (time of occurrence),
Wherein the adjustment member comprises:
A reaction rod having a predetermined length and moving back and forth with the plunger;
A bush having a center penetrated so that the front end of the reaction rod is inserted;
A first spring retainer supporting the reaction rod and the bush and slidably disposed outside the reaction rod;
A second spring retainer fixed to the rear of the reaction rod; And
And a control spring interposed between the first and second spring retainers.
The outer circumferential surface of the reaction rod is formed with a first stepped portion having a reduced diameter, and a through-hole penetrating the center of the bush is formed with a second stepped portion extending in the radial direction, when the reaction rod is coupled to the bush. The brake booster for a vehicle, characterized in that the stepped surface and the stepped surface of the second stepped portion to maintain the same surface with each other. The method of claim 1,
And the front end surface of the bush is installed to maintain the same surface as the front end surface of the reaction rod during initial brake operation. The method of claim 1,
An end portion of the valve body in contact with the reaction disk is provided with an annular portion extending radially larger than the diameter of the cylinder, and the diameter of the bush is made to correspond to the diameter of the annular portion, the bush is fitted to the annular portion is coupled to Brake booster for cars. delete The method of claim 1,
And the first spring retainer is in contact with a step surface of the first step portion and the second step portion.

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