KR100826810B1 - Brake booster - Google Patents

Abstract

A brake booster is provided to communicate a variable pressure chamber with atmosphere, to raise pressure of the variable pressure chamber rapidly, and to increase output of the brake booster immediately by catching a sleeve at a catching device and maintaining gaps between the poppet valve and the sleeve and between the poppet valve and a sheet part. A brake booster comprises a cell, a valve device(20), a cylindrical sleeve(41), and a catching device(50). The cell has a constant pressure chamber and a variable pressure chamber. The valve device is moved by pressure difference of the constant pressure chamber and a variable pressure chamber to press an output shaft(18). The valve device has a valve body(21) and a plunger(22). The valve body has first and second paths. The plunger, installed in the valve body, has a sheet part(30) contacted with a poppet valve(23) in the valve body. The sleeve, advanced and retreated at the outer part of the plunger, opens the first and second paths selectively. The catching device, installed in the valve body, releases the restriction of the sleeve. An opening and closing spring(42), installed at the outer part of the sleeve, applies elasticity to move the sleeve to the poppet valve. The catching device has a guide member(51), first and second catching protrusions(52,54), and extended parts(53).

Description

Brake booster {BRAKE BOOSTER}

1 is a cross-sectional view showing a brake booster according to the present invention.

Figure 2 is a cross-sectional view showing a valve device of the brake booster according to the present invention, showing a state in which a normal braking operation is performed.

3 is a cross-sectional view showing a valve device of the brake booster according to the present invention, showing the initial state of emergency braking.

Figure 4 is a cross-sectional view showing a valve device of the brake power booster according to the present invention, showing a state of late emergency braking.

Figure 5 is a cross-sectional view showing a valve device of the brake booster according to the present invention, showing a brake release initial state.

Figure 6 is a cross-sectional view showing a valve device of the brake booster according to the present invention, showing a late state of braking release.

7 is a perspective view showing a sleeve and a plurality of extension configurations of the brake booster according to the present invention.

8 is a cross-sectional view showing a valve device of the brake booster according to the present invention, showing a modification of the locking device.

9 is a perspective view showing the configuration of the cutting groove and the locking spring of FIG.

10 is a cross-sectional view showing the configuration of the cutting groove and the locking spring of FIG.

Explanation of symbols on the main parts of the drawings

10: cell 11: constant pressure chamber

12: transformer chamber 13: power piston

14: diaphragm 17: input shaft

18: output shaft 19: restoring spring

20: valve device 21: valve body

22: Plunger 23: Poppet Valve

25: Reaction disc 27: First communication path

28: second communication path 30: seat portion

31: support pin 41: sleeve

42: opening and closing spring 50: locking device

51: guide member 52: first locking jaw

53: extension 54: second locking jaw

55: annular coil spring

The present invention relates to a brake power booster, and more particularly, to a brake power booster capable of rapidly raising the output of the power booster when emergency braking is performed and exerting a large output even when the brake pedal is weakly pressurized. .

In general, the brake booster generates a greater braking force when the driver presses the brake pedal to generate a force much greater than that applied to the pedal. The brake booster includes a positive pressure chamber and a transformer chamber that are mutually partitioned therein. In addition, depending on the operation of the input shaft, the pressure chamber and the transformer chamber communicate with each other so that the pressure in the pressure chamber and the transformer chamber is the same, or the communication between the pressure chamber and the transformer chamber is blocked, and the transformer chamber communicates with the atmosphere so that a pressure difference is generated between the pressure chamber and the transformer chamber. A valve device is provided. The suction pressure of the vehicle engine usually works in the constant pressure chamber.

Such a power supply device is a pressure difference between the positive pressure chamber and the transformer chamber as the positive pressure chamber and the transformer chamber are blocked when the input shaft is advanced by the pressurization of the brake pedal and the transformer chamber communicates with the atmosphere. At this time, a pressure difference occurs as the pressure in the transformer chamber increases, and this pressure difference causes a large braking force to be exerted by moving the valve shaft and the power piston that divides the constant pressure chamber and the transformer chamber to press the output shaft. When this operation is made, the pressure in the transformer chamber gradually rises to the atmospheric pressure because the transformer chamber and the atmosphere communicate with each other while the entry of the input shaft is continuously maintained.

However, such a power unit is difficult to quickly increase the pressure in the transformer chamber because the size of the inlet path of the atmosphere flowing into the transformer chamber when the input shaft is pressurized. Therefore, there is a problem that it is difficult to quickly increase the output of the power plant in the situation that emergency braking is required. Especially for the elderly, it was difficult to perform emergency braking because the force to press the input shaft through the brake pedal is weak and it is difficult to continuously press the input shaft.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a brake power boosting device that can quickly increase the output of the power boosting device when performing emergency braking.

Another object of the present invention is to maintain the communication between the transformer chamber and the atmosphere continuously unless the pressure of the input shaft is released when performing emergency braking, so that the brake can exert sufficient output even when the force to press the input shaft is weak It is to provide a power plant.

The brake power supply apparatus according to the present invention for achieving the above object is a cell having a constant pressure chamber and a transformer chamber, and the constant pressure chamber and the transformer chamber in communication with the operation of the input shaft or the transformer chamber is in communication with the atmosphere and the positive pressure And a valve device for pressurizing the output shaft while moving by a pressure difference between the chamber and the transformer chamber, wherein the valve device includes a first channel for communicating the constant pressure chamber and the transformer chamber and a second channel for communicating the transformer chamber with the atmosphere. And a plunger having a seat portion provided in the valve body to retract with the input shaft and having a seat portion contactable with the poppet valve inside the valve body, the end of which is in contact with the poppet valve as the input shaft retracts. To retract outside the plunger to selectively open the first and second flow paths apart And a locking device installed in the valve body to restrain the sleeve when the plunger is advanced by emergency braking and the sleeve and the poppet valve are separated from each other and release the restraining of the sleeve when the brake is released. It is characterized by including.

In addition, the present invention is characterized in that it further comprises an opening and closing spring installed on the outside of the sleeve to give the elasticity to move the sleeve toward the poppet valve.

In addition, the locking device is fixed in the valve body and has a cylindrical guide member having a guide hole for guiding the retreat of the plunger tip in the center, a first locking jaw projecting on the outer surface of the guide member, the guide from the sleeve And a plurality of extension parts extending toward the first catching jaw outside the member and capable of elastic deformation, and a second catching jaw formed on a free end side of the plurality of extension parts so as to be caught by the first catching jaw. .

In addition, the locking device is fixed in the valve body and has a cylindrical guide member having a guide hole for guiding the retreat of the plunger tip portion in the center, a locking jaw protruding to the outer surface of the guide member, so as to be caught on the locking jaw It characterized in that it comprises a locking spring installed in the sleeve.

In addition, the sleeve is formed with a cutting groove in the direction crossing the direction of retraction for the installation of the locking spring, the locking spring is characterized in that the 'C' type spring to enter the hooking groove.

In another aspect, the present invention is characterized in that it further comprises a sealing member installed on the plunger for maintaining the airtightness between the inner surface of the sleeve and the outer surface of the plunger.

In addition, the outer diameter of the seat portion of the plunger is characterized in that corresponding to the inner diameter of the sleeve.

In addition, the opening and closing spring is characterized in that the one end is supported on the inner surface of the valve body and the other end is supported on the flange portion provided in the sleeve.

In another aspect, the present invention further comprises a movement limiting groove formed in the sleeve and a support pin which is caught in the engaging groove formed on the outer surface of the plunger to penetrate the movement limiting groove so as to limit the axial movement of the sleeve with respect to the plunger to a predetermined range. It is characterized by including.

In another aspect, the present invention includes a first support jaw provided on the outer surface of the plunger and a second support jaw formed in the sleeve to be caught by the first support jaw so as to advance the sleeve when the plunger moves forward. It is done.

In addition, the guide member includes a fixed portion fixed to the front end of the valve body, the output shaft includes a cup-shaped coupling portion coupled to the valve body in the form of surrounding the fixed portion of the guide member, the tip of the guide member It is characterized in that it comprises a reaction disk accommodated in the cup-shaped coupling portion to be supported on the elastic deformation.

In another aspect, the present invention is characterized in that it comprises a media member removably installed in the guide member to transfer the pressing force of the plunger to the reaction disk.

In addition, the locking device is characterized in that it further comprises an annular coil spring installed on the outside of the plurality of extensions.

In another aspect, the present invention is characterized in that it further comprises a sealing member provided on the guide member for maintaining the airtight between the guide member outer surface and the valve body inner surface.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the brake booster according to the present invention divides the sealed cell 10 and the inner space of the cell 10 into a forward pressure chamber 11 and a rear transformer chamber 12 at the rear. The power piston 13 and the diaphragm 14 provided in the inside of 10 are provided. The pipe 15 provided on the front of the cell 10 is connected to an external negative pressure source (such as an intake manifold of the vehicle). Therefore, the constant pressure chamber 11 is maintained at low pressure.

A cylindrical extension tube 16 extending a predetermined length rearward is provided at the rear center portion of the cell 10, and in the extension tube 16, a positive pressure is generated according to an operation of an input shaft 17 connected to a brake pedal (not shown) of a vehicle driver's seat. The chamber 11 and the transformer chamber 12 communicate with each other, or the communication between the positive pressure chamber 11 and the transformer chamber 12 is interrupted and the transformer chamber 12 is in communication with the atmosphere, thereby transforming the pressure chamber 11 and the transformer. The valve device 20 is provided to cause a pressure difference between the chambers 12.

1 and 2, the valve device 20 is provided inside the hollow valve body 21 and the valve body 21, the plunger (opening and closing the flow path in accordance with the operation of the input shaft 17 ( 22) and poppet valves (23).

The valve body 21 is installed to penetrate the extension tube 16 at the rear of the cell 10, and the power piston 13 and the diaphragm 14 are fixed to the outer surface of the front end portion entering the cell 10. Therefore, the valve body 21 moves forward together with the power piston 13 when the power piston 13 moves forward due to the pressure difference between the positive pressure chamber 11 and the transformer chamber 12.

In front of the valve body 21 inside the cell 10 is provided an output shaft 18 which penetrates the center of the cell 10 and is connected to a master cylinder (not shown), and the rear end of the output shaft 18 is elastically deformed. Possible reaction disk 25 is coupled to the valve body 21 via. For this coupling, a cup-shaped coupling portion 24 is provided at the rear end of the output shaft 18, and the reaction disk 25 is accommodated in the cup-shaped coupling portion 24. In addition, a restoring spring 19 for providing restoring force to the valve body 21 is provided outside the output shaft 18.

The valve body 21 includes a first flow path for communicating the constant pressure chamber 11 and the transformer chamber 12, and a second flow path for communicating the transformer chamber 12 with the atmosphere. The first flow path is formed in the radial direction of the hollow portion 26 to communicate with the transformer chamber 12 and the first communication path 27 formed in the longitudinal direction on the outer side of the hollow portion 26 to communicate with the positive pressure chamber 11 The second communication path 28 is a flow path that is formed when communicating with each other through the hollow portion 26, the second flow path air inlet at the rear end of the valve body 21 in a state in which the first communication path 27 is blocked ( 29 is a flow path formed when the second communication path 28 communicates with the hollow part 26.

The poppet valve 23 and the plunger 22 installed in the hollow portion 26 of the valve body 21 selectively open these first flow passages and the second flow passages as the input shaft 17 moves forward and backward. The plunger 22 is coupled to the front end of the input shaft 17 and advances with the input shaft 17, and has a seat portion 30 that opens and closes the flow path while being in contact with or spaced apart from the front end of the poppet valve 23. Poppet valve 23 is fixed to the inner surface of the valve body 21 on the outside of the input shaft 17 is provided in the form of a corrugated pipe that can be stretched.

As shown in FIG. 5, the valve device 20 has a first communication path while the poppet valve 23 is pushed backward by the seat 30 at the rear end of the plunger 22 when the input shaft 17 is retracted. By opening (27), the positive pressure chamber (11) and the transformer chamber (12) communicate with each other, and at the same time, the introduction of outside air is blocked by the contact between the seat portion (30) and the tip of the poppet valve (23). Therefore, at this time, both the positive pressure chamber 11 and the transformer chamber 12 are in a negative pressure state, so that the valve body 21 is pushed backward by the elasticity of the restoring spring 19.

When the input shaft 17 moves forward, as shown in FIG. 2, the poppet valve 23 extends forward while the contact between the poppet valve 23 and the plunger 22 seat portion 30 is released, and the first communication is performed. The air inlet 29 at the rear end of the valve body 21 communicates with the second communication path 28 by closing the furnace 27 and spaced apart from the seat 30 and the poppet valve 23. Therefore, at this time, since the positive pressure chamber 11 is maintained at the negative pressure state and the atmosphere flows into the transformer chamber 12, the power piston 13 inside the cell 10 is caused by the pressure difference between the positive pressure chamber 11 and the transformer chamber 12. It is pushed toward this constant pressure chamber 11. When the power piston 13 is pushed toward the positive pressure chamber 11, the valve body 21 also moves forward so that the valve body 21 pushes the output shaft 18 with great force.

The support pin 31 is fitted into the second communication path 28 of the valve body 21. The support pin 31 prevents the inner end of the plunger 22 and the input shaft 17 from being coupled to the inside of the valve body 21 by being caught by the locking groove 32 of the plunger 22, and the outer end of the support pin 31. It catches on the inner surface of the cell 10 to limit the retraction of the valve body 21.

In addition, the valve device 20 may rapidly increase the output by rapidly increasing the pressure of the transformer chamber 12 when the atmosphere is smoothly introduced into the transformer chamber 12 when emergency braking is performed. For this operation, the valve device 20 is provided with a cylindrical sleeve 41 removably installed on the outside of the plunger 22 and the sleeve 41 to give elasticity to move the sleeve 41 toward the poppet valve 23. When the plunger 22 is advanced by the emergency braking and the opening / closing spring 42 installed on the outside, the sleeve 41 and the poppet valve 23 are restrained, and the sleeve 41 is restrained when the brake is released. The locking device 50 for releasing the restraint) is provided. Here, the outer diameter of the seat portion 30 of the plunger 22 is made to match the inner diameter of the sleeve 41. This causes the end of the sleeve 41 to retreat outside the seat portion 30 of the plunger 22 in contact with or spaced from the poppet valve 23 as the input shaft 17 retreats, so that the sleeve 41 is separated from the first channel. The second channel could be opened selectively.

The locking device 50 is fixed in the valve body 21 and protrudes on the outer surface of the cylindrical guide member 51, the guide member 51 having a guide hole 51a for guiding the retraction of the tip of the plunger 22 at the center thereof. A plurality of extension portions 53 and first catching jaws extending from the sleeve 41 to the first catching jaw 52 outside the guide member 51 and being elastically deformed. And a second catching jaw 54 formed on the free end side of the plurality of extension parts 53 so as to be caught by the 52. As shown in FIG. 7, the plurality of extension parts 53 are arranged at equal intervals on the outside of the guide member 51 so as to surround the outer surface of the guide member 51. In addition, the locking device 50 includes an annular coil spring 55 which is installed outside the plurality of extensions 53. The annular coil spring 55 tightens the free ends of the plurality of extension parts 53 toward the outer surface of the guide member 51 so that the second catching jaw 54 can be caught by the first catching jaw 52. Of course, since the plurality of extension parts 53 have their own elasticity, the second catching jaw 54 may be caught by the first catching jaw 25 even when the annular coil spring 55 is not present. The spring 55 tightens the extension 53 so that this locking operation can be made stable. In FIG. 7, reference numeral 53a is a spring groove for installing the annular coil spring 55.

As shown in FIG. 2, the opening / closing spring 42 is supported by a stepped portion 21a of the inner surface of the valve body 21, and the other end thereof is supported by a flange portion 43 provided on the outer surface of the sleeve 41. . The outer surface of the plunger 22 is provided with a sealing member 61 to maintain the airtightness between the inner surface of the sleeve 41 and the plunger 22. In addition, the sleeve 41 is provided with a movement limiting groove 44 to limit the axial movement of the sleeve 41 to the set range, the support pin 31 is coupled through the movement restriction groove 44 through. At this time, the support pin 31 enters the engaging groove 32 of the plunger 22 to be movable in the axial direction of the predetermined section.

In addition, the plunger 22 is provided with a first supporting jaw 62 on the outer surface so that the sleeve 41 can be advanced when the plunger 22 is advanced, and the first supporting jaw 62 is caught by the sleeve 41. A stepped second support jaw 45 is formed. The second support jaw 45 is formed at the boundary between the sleeve 41 and the plurality of extensions 53.

The guide member 51 has a fixing portion 51b fixed to the front end side of the valve body 21, and a sealing member 51c for airtightness is installed at a portion to which the fixing portion 51b is coupled. In addition, the cup-shaped coupling portion 24 of the output shaft 18 is coupled in a form surrounding the fixing portion 51b of the guide member 51. The reaction disk 25 is supported on the inner surface of the cup-shaped coupling portion 24 while the other side is supported at the tip of the guide member 51 in the state accommodated in the cup-shaped coupling portion 24. In addition, in the guide member 51, an intermediate member 57 capable of advancing and retreating a predetermined section is provided to transmit the pressing force of the plunger 22 to the center of the reaction disk 25.

The following describes the operation of the valve device of such a brake booster.

When a normal braking operation (not emergency braking) is performed, as shown in FIG. 2, the plunger 22 moves forward and the sleeve 41 moves forward by the plunger 22 as the input shaft 17 enters. End portions of the seat portion 30 and the sleeve 41 of the 22 are spaced apart from the poppet valve 23 and the poppet valve 23 blocks the first communication path 27.

Therefore, at this time, communication between the constant pressure chamber 11 and the transformer chamber 12 is blocked, and the transformer chamber 12 and the air communicate with each other, so that the pressure of the transformer chamber 12 increases. When the power piston 13 is advanced by the pressure difference between the constant pressure chamber 11 and the transformer chamber 12 according to the pressure rise of the transformer chamber 12, the valve body 21 is also advanced and presses the output shaft 18. . At this time, since the valve body 21 is advanced, the poppet valve 23 and the seat portion 30 of the plunger and the end portions of the sleeve 41 may contact each other, but the pressurization of the plunger 22 by the input shaft 17 This operation is repeated since it is maintained. Therefore, the braking operation is performed while the pressure in the transformer chamber 12 gradually rises.

On the other hand, when performing the emergency braking, as shown in Figure 3, in addition to the braking operation as described above, the plunger 22 advances rapidly and enters more deeply at the beginning of the braking operation, so that the sleeve 41 is locked (50). It is caught by the outer surface of the guide member 51 by the. That is, in this case, the second locking jaw 54 of the extension 53 extending from the sleeve 41 is caught over the first locking jaw 52 of the guide member 51. Therefore, at this time, as shown in FIG. 4, the guide member 51 advances by the advancement of the valve body 21, and the sleeve 41 also advances together by the advancement of the guide member 51. The end is spaced apart from the poppet valve 23. In this case, the first supporting jaw 62 of the plunger 22 is caught by the support pin 31, and the support pin 31 is caught in the movement limiting groove 44 of the sleeve 41. Seat portion 30 of the) also maintains a state spaced apart from the poppet valve (23). Therefore, when the emergency braking is performed, since the inflow of the air toward the transformer chamber 12 is smoothly performed, the pressure rise of the transformer chamber 12 is quickly performed. That is, the output of the power booster rises rapidly. In addition, when the emergency braking is performed, the braking operation is canceled because the space between the poppet valve 23 and the sleeve 41 and the poppet valve 23 and the seat part 30 is maintained even when the pressing force of the input shaft 17 is weak. Lasts unless

When the brake is released, as illustrated in FIG. 5, the sleeve 41 is pulled backward as the input shaft 17 and the plunger 22 are retracted, thereby releasing the engagement of the sleeve 41. At this time, the support pin 31 caught by the first support jaw 62 of the plunger 22 is pulled backward, and the support pin 31 is caught by the movement limiting groove 44 of the sleeve 41 to lift the sleeve 41. Since the second catching jaw 54 is pulled backward, the second catching jaw 54 is released from the first catching jaw 52 of the guide member 51.

When the braking is released in this manner, as shown in FIG. 5, first, the seat portion 30 of the plunger 22 contacts the poppet valve 23 and pushes the poppet valve 23 backward so that the inflow of air is blocked. At the same time, the first communication path 27 is opened and the positive pressure chamber 11 and the transformer chamber 12 communicate with each other. After that, as shown in FIG. 6, the sleeve 41 is retracted by the elasticity of the opening / closing spring 42 so that the end of the sleeve 41 comes into contact with the poppet valve 23. Therefore, at this time, the pressure in the transformer chamber 12 is lowered so that the pressures in the positive pressure chamber 11 and the transformer chamber 12 are equal, so that the valve body 21 is retracted by the elasticity of the restoring spring 19, and the valve body 21 is closed. The output shaft 18 also retreats by retreating.

8 to 10 show another embodiment of the locking device. The locking device 150 is fixed to the valve body 21 and one side of the cylindrical guide member 151 for guiding the retraction of the sleeve 41 and the plunger 22 by entering the inside of the sleeve 41, the guide member It includes an annular locking projection 152 formed to protrude to the outer surface of the 151, the locking spring 155 provided in the extension portion 153 of the sleeve 41 to be caught by the locking projection 152.

As illustrated in FIG. 9, the locking spring 155 is formed of an elastic "C" type spring, and has cutout grooves 154 formed at upper and lower portions of the extension part 153 extending from the sleeve 41, respectively. A portion thereof is installed to enter into the sleeve 41. Accordingly, the locking spring 155 may be caught by the locking step 152 formed in the guide member 151 when the sleeve 41 moves forward and backward on the outer surface of the guide member 151. The rest of the configuration is the same as the above-described example, so description thereof will be omitted.

As described in detail above, the brake powering device according to the present invention is the communication between the transformer chamber and the atmosphere because the sleeve is caught by the locking device when the emergency braking is performed, and the separation between the poppet valve and the sleeve and the poppet valve and the seat is maintained. This can be maintained continuously. Therefore, the inflow of the air to the transformer chamber is smoothly performed, so that the pressure rise of the transformer chamber is quickly performed, thereby increasing the output of the power plant.

In addition, the present invention has the effect that the output of the transformer and the atmosphere is maintained unless the braking operation is released after the emergency braking, even if the force to press the input shaft is weak.

Claims (14)

Pressurizing the output shaft while moving by the pressure difference between the positive pressure chamber and the transformer chamber, the cell having a constant pressure chamber and the transformer chamber and the positive pressure chamber and the transformer chamber in communication with the atmosphere or the transformer chamber according to the operation of the input shaft. A valve body having a first flow path for communication between the constant pressure chamber and the transformer chamber and a second flow path for communication between the transformer chamber and the atmosphere, and the valve body to retreat with the input shaft; A brake booster comprising: a plunger having a seat portion installed therein and in contact with a poppet valve inside the valve body; Cylindrical sleeves are retractably installed on the outside of the plunger so as to selectively open the first and second flow paths while their ends are in contact with or spaced apart from the poppet valve as the input shaft moves forward and backward; And a locking device installed in the valve body to restrain the sleeve when the sleeve and the poppet valve are separated from each other when moving forward and to release the sleeve when the brake is released. The method of claim 1, And an opening / closing spring installed outside the sleeve to impart elasticity to move the sleeve toward the poppet valve. The method of claim 2, The locking device is fixed in the valve body and has a cylindrical guide member having a guide hole in the center for guiding the advance and retreat of the plunger tip, a first locking jaw projecting on the outer surface of the guide member, and the guide member from the sleeve. A brake including a plurality of extension portions extending toward the first catching jaw outside and capable of elastic deformation, and a second catching jaw formed on a free end side of the plurality of extension portions so as to be caught by the first catching jaw; Power system. The method of claim 2, The locking device is fixed in the valve body and has a cylindrical guide member having a guide hole in the center for guiding the retreat of the plunger tip, a locking jaw protruding on the outer surface of the guide member, so as to be caught by the locking jaw A brake booster comprising a locking spring installed in the sleeve. The method of claim 4, wherein The sleeve is formed with a cutting groove in the direction crossing the direction of retraction for the installation of the locking spring, The locking spring is a brake booster, characterized in that the 'C' type spring is caught entering the incision groove. The method of claim 2, And a sealing member installed on the plunger to maintain the airtightness between the inner surface of the sleeve and the outer surface of the plunger. The method of claim 6, An outer diameter of the seat portion of the plunger corresponds to the inner diameter of the sleeve. The method of claim 2, The opening and closing spring of the brake booster, characterized in that the one end is supported on the inner surface of the valve body and the other end is supported on the flange portion provided in the sleeve. The method of claim 2, It further comprises a movement limiting groove formed in the sleeve and a support pin that is caught in the engaging groove formed on the outer surface of the plunger to limit the axial movement of the sleeve with respect to the plunger to the set range. Brake booster. The method of claim 2, And a first supporting jaw provided on an outer surface of the plunger so as to advance the sleeve when the plunger moves forward, and a second supporting jaw formed in the sleeve to be caught by the first supporting jaw. Device. The method of claim 3, The guide member includes a fixing part fixed to the front end of the valve body, The output shaft includes a cup-shaped coupling portion coupled to the valve body in a form surrounding the fixed portion of the guide member, And a reaction disk accommodated in the cup-shaped coupling part so as to be supported at the tip of the guide member and capable of elastic deformation. The method of claim 11, And a mediating member removably installed in the guide member to transmit the pressing force of the plunger to the reaction disk. The method of claim 3, The latching device further includes an annular coil spring installed outside the plurality of extensions. The method of claim 11, And a sealing member installed on the guide member for maintaining airtightness between the guide member outer surface and the valve body inner surface.

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