JP2013129374A - Negative pressure booster and brake booster using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more simplify an assembling operation of an actuation assist mechanism and a dimension management of the actuation assist mechanism while performing a plurality of pieces of actuation assist actuation upon emergency actuation.SOLUTION: Upon non-actuation, first and fourth parts 33a, 34a of position to be regulated of a vacuum valve seat member 29 are brought into contact with first and second straight line-shaped position regulating parts 31b, 31c to regulate the vacuum valve seat member 29 at the non-actuation position. Meanwhile, upon first emergency brake actuation, second and fifth parts 33b, 34b of position to be regulated are brought into contact with the first and second straight line-shaped position regulating parts 31b, 31c which are expanded and opened to regulate the vacuum valve seat member 29 at a first emergency brake actuation position. Further, upon second emergency brake actuation, third and sixth parts 33c, 34c of position to be regulated are brought into contact with the first and second straight line-shaped position regulating parts 31b, 31c which are further expanded and opened to regulate the vacuum valve seat member 29 at a second emergency brake actuation position.

Description

  The present invention provides a negative pressure capable of obtaining a larger output (braking force) than in normal operation with the same input (brake operating force) as in normal operation (during normal brake operation) during operation assist (during emergency brake operation). The present invention relates to a technical field of a booster and a brake booster using the same. In the claims and the description of the claims, “front” refers to the direction in which the input shaft advances (that is, the operating direction) by input, and “rear” refers to the direction in which the input shaft returns due to the disappearance of input.

  2. Description of the Related Art Conventionally, in a brake system for an automobile such as a passenger car, a negative pressure booster using negative pressure is used as a brake booster. In such a conventional general negative pressure booster, when the input shaft moves forward during normal brake operation due to normal depression of the brake pedal, the valve plunger connected to the input shaft also moves forward to the valve body. The valve body of the arranged control valve is seated on the vacuum valve seat formed on the valve body and the vacuum valve is closed, and the atmospheric valve seat formed on the valve plunger is separated from the valve body of the control valve. The atmospheric valve is opened, and the variable pressure chamber in which negative pressure is introduced when not operating is shut off from the constant pressure chamber in which negative pressure is constantly introduced and communicated with the atmosphere. Then, the air is introduced into the variable pressure chamber through the open atmospheric valve, and a differential pressure is generated between the variable pressure chamber and the constant pressure chamber, so that the power piston moves forward. A booster boosts the input of the input shaft (that is, pedaling force) by a predetermined servo ratio and outputs the boosted signal. Due to the output of the negative pressure booster, the piston of the master cylinder moves forward, the master cylinder generates a master cylinder pressure, and the wheel cylinder is operated by this master cylinder pressure, and the normal brake is operated.

  At this time, generally, as shown by the solid line in FIG. 8, during normal braking operation, the negative pressure booster does not transmit the reaction force from the output shaft to the input shaft when the input is small, and the input is somewhat large and counteracts. When the reaction force is transmitted to the input shaft by the force mechanism, it has an input / output characteristic having a so-called jumping (Js) characteristic that substantially generates a predetermined output.

  By the way, in a brake system, it may be necessary to generate a large desired braking force more quickly and quickly than when a normal brake is actuated at the time of emergency braking. Therefore, as a negative pressure booster used in the brake system, a BA mechanism for performing a brake assist operation (hereinafter also referred to as BA) that quickly generates a large brake force with a small pedal depression force, that is, an operation assist mechanism is provided. A negative pressure booster has been proposed (see, for example, Patent Document 1).

  In the negative pressure booster disclosed in Patent Document 1, a tubular member having a vacuum valve seat and constituting a BA operating mechanism is provided on the valve body so as to be slidable relative to the valve body, and the tubular member is always provided by a spring. The atmospheric valve is biased in the opening direction, and the tubular member is normally held at the non-operating position by the U-shaped holding means. Then, when the brake pedal is depressed at a pedal depression speed faster than the normal pedal depression speed during emergency braking, the valve plunger moves forward at a speed faster than normal. Then, the holding of the cylindrical member by the holding means is released by the advancement of the valve plunger at this high speed, so that the atmospheric valve is made larger than usual by moving the cylindrical member in the direction in which the atmospheric valve opens with a spring. Open the valve. As a result, the jumping amount of the negative pressure booster increases from the normal time, and the output increases rapidly. Thus, the BA operation at the time of emergency braking is performed.

  However, in the negative pressure booster described in Patent Document 1, since the cylindrical member for performing the BA operation is composed of two members, not only the configuration of the BA mechanism is complicated, but also the number of parts is large. It has become. In addition, the negative pressure booster described in Patent Document 1 can perform only one BA operation during an emergency brake operation. For this reason, it is difficult to perform the BA operation in detail according to the emergency brake situation.

  Therefore, by performing two BA operations at the time of emergency brake operation so that the BA operation can be performed according to the situation of the emergency brake, the cylindrical member that performs the BA operation is configured as a single member, A negative pressure booster has been proposed in which the structure of the mechanism is simplified and the number of parts is reduced (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 2010-23779. Japanese Patent No. 4519650.

  However, in the BA mechanism in the negative pressure booster disclosed in Patent Document 2, the clip-shaped holding means for holding the cylindrical member of the BA mechanism in the non-operating position has a complicated shape. For this reason, there is a problem that the assembling work of the holding means is troublesome and the number of assembling steps is increased, and the size management of the BA mechanism such as the cylindrical member and the holding means becomes troublesome.

  The present invention has been made in view of such circumstances, and an object of the present invention is to perform assembling work of an operation assist mechanism and dimensions of the operation assist mechanism while enabling a plurality of operation assist operations to be performed in an emergency operation. It is an object of the present invention to provide a negative pressure booster and a brake booster using the negative pressure booster that can be managed more easily.

  In order to solve the above-described problems, a negative pressure booster according to the present invention is provided with a valve body disposed in a housing so as to be movable forward and backward, and disposed so as to be relatively movable with respect to the valve body. The valve plunger that moves by the input of the valve, closes the vacuum valve and opens the atmospheric valve to introduce the atmosphere into the housing, and generates the output according to the input in the atmosphere formed in the housing, and the operation assist mechanism operates. In the negative pressure booster that makes the output larger than the output during normal operation when the operation assist mechanism does not operate, the operation assist mechanism is provided movably on the valve body, and the atmospheric valve is moved when the operation assist mechanism is not operated. The jumping amount that does not move with respect to the valve body and starts to generate an output with respect to the input during operation is greater than the jumping amount during normal operation. A vacuum valve seat member for operating the atmospheric valve, a vacuum valve seat member biasing means for constantly biasing the vacuum valve seat member toward the atmospheric valve, and the vacuum valve seat member provided on the valve body A U-shaped vacuum valve seat member position restricting member that restricts the position of the valve body in the axial direction and can be expanded elastically, and the vacuum valve seat member position restricting member provided on the vacuum valve seat member A vacuum valve seat member position regulating member that regulates the position of the valve body in the axial direction of the valve body by abutting on the valve, and the input shaft provided at the valve plunger is faster than that during normal operation. A position restricting member expansion control unit that opens the vacuum valve seat member position restricting member to actuate the vacuum valve seat member when operated at an operating speed, and the vacuum valve seat member position restricting member comprises: Regulation of the position of the vacuum valve seat member It is characterized by having at least a plurality of the position regulating portion for regulating a plurality of different positions axially of the valve body of the vacuum valve seat member by abutting the timber, respectively.

Further, the negative pressure booster of the present invention is characterized in that the vacuum valve seat member position restricting member has a predetermined number of steps for setting the plurality of position restricting portions.
Furthermore, the negative pressure booster of the present invention is characterized in that the vacuum valve seat member position restricting member has a plurality of position restricting surfaces that can selectively contact the plurality of position restricting portions.
Furthermore, the negative pressure booster of the present invention is characterized in that the vacuum valve seat member position restricting member has a predetermined number of steps for setting the plurality of position restricting surfaces.

  On the other hand, the brake booster of the present invention is a brake booster that outputs a braking force obtained by boosting the brake operating force with the negative pressure booster, wherein the negative pressure booster is the negative pressure booster of the present invention described above. One of the force devices is characterized in that the operation assist mechanism is a brake assist mechanism that operates when an emergency brake is operated and outputs a larger brake force with the same brake operation force than when a normal brake is operated.

  According to the negative pressure booster and the brake booster according to the present invention configured as described above, the vacuum valve seat member of the operation assist mechanism that performs the assist operation by operating the atmospheric valve is movable in the valve body. Provided. The vacuum valve seat member is provided with a vacuum valve seat member position restricting member. In addition, a U-shaped, elastically expandable and vacuum valve seat member position regulating member that regulates the position of the vacuum valve seat member (the position in the axial direction of the valve body) is provided in the valve body and in the axial direction of the valve body. Provided immovable. The vacuum valve seat member position restricting member includes a plurality of position restricting portions that respectively restrict a plurality of different positions in the axial direction of the valve body of the vacuum valve seat member by contacting the vacuum valve seat member position restricting member. Have. Thus, a plurality of different positions in the axial direction of the valve body of the vacuum valve seat member are set by the plurality of position restricting portions, so that a plurality of assist operations can be performed during a plurality of emergency operations. Therefore, the vacuum valve seat member position regulating member for regulating the position of the vacuum valve seat member is formed into a simple U-shape, and the assist operation is performed by performing a plurality of assist operations at the time of a plurality of emergency operations. It becomes possible to carry out according to the situation of operation.

  In addition, since the vacuum valve seat member position restricting member can be formed in a simple U-shape, the assembly work of the vacuum valve seat member position restricting member can be simplified and the number of assembly steps can be reduced. Dimensional management of assist mechanisms such as valve seat member position regulating members can be made easier.

It is sectional drawing which shows an example of embodiment of the negative pressure booster which concerns on this invention in a non-operation state. It is a partial expanded sectional view which expands and shows the part of the vacuum valve and atmospheric valve in FIG. (A) is a front view of a vacuum valve seat member, (B) is a fragmentary sectional view which follows the IIIB-IIIB line in (A). It is a perspective view of a vacuum valve seat member position control member. It is a perspective view of a position control member retainer. It is a figure which shows the brake system by which the negative pressure booster was used as a brake booster. (A) is a partial cross-sectional view showing when the negative pressure booster of the example shown in FIG. 1 is not operating, (B) is a partial cross-sectional view showing when the first emergency brake is operating of the negative pressure booster, (C) These are the fragmentary sectional views which show the time of the 2nd emergency brake action of a negative pressure booster. It is a figure which shows the input-output characteristic of a negative pressure booster. FIG. 3 is a partially enlarged cross-sectional view similar to FIG. 2, showing an enlarged view of a vacuum valve and an atmospheric valve when the first emergency brake is activated. FIG. 3 is a partially enlarged cross-sectional view similar to FIG. 2, showing an enlarged view of a vacuum valve and an atmospheric valve during a second emergency brake operation. It is a front view similar to FIG. 3 (A) which shows the vacuum valve seat member of the other example of embodiment of the negative pressure booster of this invention. (A) is the perspective view similar to FIG. 4 which shows the vacuum valve seat member position control member of the example shown in FIG. 11, (B) is sectional drawing which follows the XIIB-XIIB line in (A). (A) is a partial cross-sectional view showing when the negative pressure booster of the example shown in FIG. 11 is not in operation, (B) is a partial cross-sectional view showing when the first emergency brake is operating in the negative pressure booster, (C) These are the fragmentary sectional views which show the time of the 2nd emergency brake action of a negative pressure booster.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of an embodiment of a negative pressure booster according to the present invention in a non-operating state, and FIG. 2 is a partially enlarged cross-sectional view showing enlarged portions of a vacuum valve and an atmospheric valve in FIG. is there. In the following description, “front” and “rear” indicate “left” and “right” in each figure, respectively.

  First, in the negative pressure booster of this example, the same components as the conventional negative pressure booster described in Patent Document 1 and the configuration of the negative pressure booster described in Patent Document 1 are different. Components that are not directly related will be briefly described. 1 and 2, reference numeral 1 is a negative pressure booster, 2 is a front shell, 3 is a rear shell, 4 is a valve body disposed in a housing constituted by the front shell 2 and the rear shell 3 so as to freely advance and retract, 5 is a power piston comprising a power piston member 6 attached to the valve body 4 and a diaphragm 7 which is airtightly provided between the valve body 4 and both shells 2, 3, and 8 is used to power the space in both shells 2, 3. One of the two chambers defined by the piston 5 is a constant pressure chamber into which negative pressure is normally introduced, and 9 is the other of the two chambers described above, and the atmospheric pressure during operation of the negative pressure booster 1 is introduced. A variable pressure chamber 10 is a valve plunger, 11 is connected to a brake pedal (not shown), and an input shaft for controlling the operation of the valve plunger 10, 12 is movably provided on the valve body 4, and a circle A valve body having an annular atmospheric valve portion 12a and annular first and second vacuum valve portions 12b, 12c, 13 an annular first vacuum valve seat provided in the valve body 4, and 14 a valve plunger An annular atmospheric valve seat formed in 10, 15 is a first vacuum valve constituted by a first vacuum valve portion 12 b and a first vacuum valve seat 13, and 16 is constituted by an atmospheric valve portion 12 a and an atmospheric valve seat 14. The atmospheric valve 17 includes a vacuum valve 15 and an atmospheric valve 16 arranged in series with each other. The control valve 18 selectively switches the variable pressure chamber 9 to the constant pressure chamber 8 and the atmospheric air. The first valve control spring 19 is always urged in the direction in which the first vacuum valve portion 12b is seated on the first vacuum valve seat 13, and 19 is attached between the rear shell 3 and the input shaft 11 and has an air inlet 19a. The boot 20 is provided in the valve body 4 An air introduction passage 21 for introducing air, a vacuum passage 21 provided in the valve body 4 for communicating the variable pressure chamber 9 and the constant pressure chamber 8, and 22 being inserted into a key hole 4 a formed in the valve body 4. 4 is a key member that regulates the relative movement of the valve plunger 10 with respect to 4 to a predetermined amount that is defined by the axial width of the key hole 4a, and that defines each retreat limit of the valve body 4 and the valve plunger 10. A member, 24 is a reaction disk, 25 is an output shaft, 26 is a return spring, and 27 is a negative pressure inlet for introducing negative pressure from a negative pressure source (not shown) into the constant pressure chamber 8.

  In addition, when the negative pressure booster 1 is not operated, a predetermined first in the axial direction is formed between the front end face of the spacing member 23 and the rear end face of the reaction disk 24 facing the front end face of the spacing member 23. A gap C1 is set. A predetermined second gap C2 in the axial direction is set between the rear end surface of the spacing member 23 and the valve body 4.

  Although not shown, the rear end of the master cylinder enters the constant pressure chamber 8 through the front shell 2 and the piston of the master cylinder is connected to the output shaft 25, as in a conventional general negative pressure booster. It is to be activated. In that case, the portion of the master cylinder that slidably penetrates the front shell 2 is sealed by an appropriate sealing means (not shown), and the constant pressure chamber 8 is shut off from the atmosphere in an airtight manner. Further, as in the prior art, the valve body 4 penetrates the rear shell 3 so as to be movable, and the variable pressure chamber 9 is hermetically shut off from the atmosphere by a seal member 28 in this penetration portion.

Next, the structure of the characteristic part of the negative pressure booster 1 of this example is demonstrated.
As shown in FIG. 2, in the negative pressure booster 1 of this example, a vacuum valve seat member 29, which is a cylindrical member, can be slid in an airtight manner by a seal member 30 in the axial inner hole 4 b of the valve body 4. It is mated. A vacuum valve seat member position restricting member 31 is provided in the valve body 4 at a position ahead of the key member 22.

3A is a front view of the vacuum valve seat member, and FIG. 3B is a partial cross-sectional view taken along line IIIB-IIIB in FIG.
The vacuum valve seat member 29 is formed in a cylindrical shape. As shown in FIGS. 3 (A) and 3 (B), a second vacuum valve seat 32 is provided at the rear end of the vacuum valve seat member 29 so as to be located on the inner peripheral side from the first vacuum valve seat 13. It has been. Since the vacuum valve seat member 29 can slide relative to the valve body 4, the second vacuum valve seat 32 can also move relative to the valve body 4. Further, the vacuum valve seat member 29 is provided with a pair of first and second key member through holes 29a and 29b through which the key member 22 passes along the circumferential direction. Further, the vacuum valve seat member 29 has a pair of first and second position restricting member through holes 29c and 29d through which the vacuum valve seat member position restricting member 31 penetrates in the circumferential direction and the first and key member through holes, respectively. 29a and 29b are provided in front of the position.

  Further, the vacuum valve seat member 29 includes first and second vacuum valve seat member position restriction members 33 whose positions are controlled in the axial direction (left and right direction) of the valve body 4 by the vacuum valve seat member position restriction member 31. 34 are provided corresponding to the first and second position restricting member through holes 29c and 29d, respectively. The first vacuum valve seat member position restriction member 33 has three first to third position restriction portions 33a, 33b, and 33c. In that case, the first position-regulated portion 33a is located farthest (in the direction of the control valve 17), and the second position-regulated portion 33b is in front of the first position-regulated portion 33a (in the direction opposite to the control valve 17). Further, the third position restricting portion 33c is located in front of (the same as) the second position restricting portion 33b, that is, the foremost position. Therefore, the first vacuum valve seat member position restricting member 33 is formed in a stepped shape having two steps. On the other hand, the second vacuum valve seat member position restriction member 34 has three fourth to sixth position restriction portions 34a, 34b, 34c. In that case, the fourth position-restricted portion 34a is located farthest (in the direction of the control valve 17), and the fifth position-restricted portion 34b is forward of the fourth position-restricted portion 34a (in the direction opposite to the control valve 17). Further, the sixth position restricting portion 34c is located in front of (the same as) the fifth position restricting portion 34b, that is, most forward. Therefore, the second vacuum valve seat member position restricting member 34 is also formed in a stepped shape having two steps.

  These first and second vacuum valve seat member position restricting members 33 and 34 are provided symmetrically with the same size with respect to a straight line along the axial direction of the valve body 4. In that case, the positions of the first and fourth position restricting portions 33a, 34a in the axial direction of the valve body 4 are set to the same position, and the second and fifth position restricting portions 33b, 34b are set to the shaft of the valve body 4. The position with respect to the direction is set to the same position, and the positions of the third and sixth position restriction portions 33c, 34c with respect to the axial direction of the valve body 4 are set to the same position. As shown in FIGS. 1 and 2, the vacuum valve seat member 29 is always biased toward the control valve 17 by a vacuum valve seat member biasing spring 35 (corresponding to the vacuum valve seat member biasing means of the present invention). Has been.

FIG. 4 is a perspective view of the vacuum valve seat member position regulating member.
As shown in FIG. 4, the vacuum valve seat member position restriction member 31 is provided in the valve body 4 at a position ahead of the key member 22. The vacuum valve seat member position restricting member 31 is a bar-shaped elastic member having a rectangular cross section made of, for example, Pom material, Peak resin, or metal, and is formed as a U-shaped clip as a whole. The vacuum valve seat member position restricting member 31 includes a curved portion 31a through which the valve plunger 10 passes and a pair of first and second linear position restricting portions that respectively penetrate the first and second position restricting member through holes 29c and 29d. 31b, 31c. The first and second linear position restricting portions 31b, 31c have first and second engaging grooves 31d, 31e provided at their tip portions, respectively.

  The vacuum valve seat member position restricting member 31 is provided so as not to move relative to the valve body 4 in the axial direction (left-right direction) of the valve body 4, and the first and second linear position restricting portions 31b, 31c is provided so as to be relatively movable in a direction away from and approaching each other (a direction orthogonal to the axial direction of the valve body 4). In this case, in a state where the vacuum valve seat member position restricting member 31 is assembled to the valve body 4, the first and second linear position restricting portions 31b and 31c are elastically slightly expanded from the free state (that is, separated from each other). ). Therefore, when the vacuum valve seat member position restricting member 31 is assembled to the valve body 4, the first and second linear position restricting portions 31b and 31c are urged by the elasticity so as to approach each other.

  Further, the vacuum valve seat member position restricting member 31 is further urged so that the first and second linear position restricting portions 31b and 31c are brought closer to each other by the position restricting member retainer 36 in the assembled state to the valve body 4. Has been. As shown in FIG. 5, the position restricting member retainer 36 includes a C-shaped elastic rod 36a, a pair of first and second support members 36b and 36c provided at both ends of the elastic rod 36a, and the first of them. A pair of first and second engaging pins 36d, 36e projecting from the first and second support members 36b, 36c, respectively. Then, in a state where the vacuum valve seat member position restricting member 31 is assembled to the valve body 4, the first and second engagement pins 36 d and 36 e are respectively connected to the first and second engagement pins 36 d and 36 e as indicated by a two-dot chain line in FIG. 2 Engage in the engaging grooves 31d and 31e. In that case, the position restricting member retainer 36 is elastically slightly expanded from the free state (that is, the first and second engaging pins 36d and 36e are separated from each other) and assembled to the vacuum valve seat member position restricting member 31.

  The expansion control of the first and second linear position restriction portions 31 b and 31 c of the vacuum valve seat member position restriction member 31 is performed by a position restriction member expansion control portion 37 provided on the valve plunger 10. The position restricting member expansion control unit 37 is formed in a truncated truncated cone shape having a small diameter on the front side and a large diameter on the rear side. Then, after the valve plunger 10 moves forward during operation of the negative pressure booster 1 and the conical outer peripheral surface of the position restricting member expansion control part 37 comes into contact with the first and second linear position restricting parts 31b and 31c. As the valve plunger 10 advances, the conical outer peripheral surface of the position restricting member expansion control unit 37 gradually expands the first and second linear position restricting portions 31b and 31c.

  The front surfaces of the first and second linear position restricting portions 31b and 31c are first and second position restricting surfaces 31f.31g, respectively. One first position regulating surface 31f can be selectively brought into contact with the first to third position regulated portions 33a, 33b, 33c. The other second position restricting surface 31g can be selectively brought into contact with the fourth to sixth position restricted portions 34a, 34b, 34c.

  The vacuum valve seat member 29, the vacuum valve seat member position restricting member 31, the second vacuum valve seat 32, the first and second vacuum valve seat member position restricting members 33, 34, the vacuum valve seat member biasing spring 35, The position restricting member expansion control unit 37 constitutes a brake assist mechanism (BA mechanism; corresponding to the operation assist mechanism of the present invention).

  The negative pressure booster 1 of this example configured in this way is used as a brake booster in the brake system 38 as shown in FIG. 6, for example. The brake system 38 in the example shown in FIG. 6 is a two-system brake system, which includes a brake pedal 39, a negative pressure booster 1 as a brake booster, a tandem master cylinder 40, a reservoir tank 41, a brake cylinder such as a wheel cylinder. 42, 43, 44, 45 are provided.

Next, each operation of the negative pressure booster 1 and the brake system 38 configured in this way will be described.
(When negative pressure booster 1 is not operating)
A normal negative pressure is introduced into the constant pressure chamber 8 of the negative pressure booster 1 through the negative pressure inlet 27. Moreover, in the non-operation state of the negative pressure booster 1 shown in FIGS. 1 and 2, the key member 22 is in contact with the rear shell 3 and is in a backward limit. Accordingly, the valve member 4 and the valve plunger 10 are set to the backward limit by the key member 22, and the power piston 5, the input shaft 11 and the output shaft 25 are also set to the backward limit. In this state, the first vacuum valve portion 12b is seated on the first vacuum valve seat 13, and the atmospheric valve 12 is lightly seated on the atmospheric valve seat 14 or slightly separated from the atmospheric valve seat 14 ( In the illustrated example, the atmospheric valve 12 is seated on the atmospheric valve seat 14).

  Further, as shown in FIGS. 1 and 2, since the valve plunger 10 is in the illustrated non-operating position when the negative pressure booster 1 is not operated, the conical outer peripheral surface of the position restricting member expansion control unit 37 is the first one. The first and second linear position restricting portions 31b and 31c are separated from each other. Therefore, as shown in FIGS. 2 and 7A, the first and second linear position restricting portions 31b and 31c of the vacuum valve seat member position restricting member 31 are not expanded by the position restricting member expansion control portion 37. The initial position is set. The vacuum valve seat member 29 is biased toward the control valve 17 by the spring force of the vacuum valve seat member biasing spring 35, so that the vacuum valve seat member 29 has its first and fourth position restricting portions 33a. , 34a are held at positions in contact with the first and second position restricting surfaces 31f, 31g of the first and second linear position restricting portions 31b, 31c of the vacuum valve seat member position restricting member 31. At this position of the vacuum valve seat member 29, the second vacuum valve portion 12 c is not seated on the second vacuum valve seat 32 of the vacuum valve seat member 29.

  Therefore, when the negative pressure booster 1 is in an inoperative state, the control valve 17 communicates the variable pressure chamber 9 with the constant pressure chamber 8 and blocks it from the atmosphere. Therefore, a negative pressure is also introduced into the variable pressure chamber 9 so that no substantial differential pressure is generated between the constant pressure chamber 8 and the variable pressure chamber 9, and the power piston 5 and the output shaft 25 are both shown in FIGS. The non-operating position shown in FIG. That is, the negative pressure booster 1 does not generate an output, and each brake cylinder 42, 43, 44, 45 does not brake the corresponding wheels 46, 47, 48, 49.

  Further, the above-described first gap C1 is set between the spacing member 23 and the reaction disk 24. Further, the above-described second gap C <b> 2 is set between the spacing member 23 and the valve body 4. Further, the valve plunger 10 and the spacing member 23 are lightly connected.

(At the time of normal brake operation of the negative pressure booster 1)
When the brake pedal is stepped on at the stepping speed at the time of normal brake operation in order to perform normal braking, the input shaft 11 moves forward and the valve plunger 10 moves forward as in the conventional general negative pressure booster. As the valve plunger 10 advances, the first vacuum valve portion 12b of the valve body 12 is seated on the first vacuum valve seat 13, the vacuum valve 15 is closed, and the atmospheric valve seat 14 is separated from the atmospheric valve portion 12a of the valve body 12. Then, the atmospheric valve 16 is opened. That is, the variable pressure chamber 9 is disconnected from the constant pressure chamber 8 and communicated with the atmosphere. Therefore, atmospheric pressure air is introduced into the variable pressure chamber 9 through the atmosphere introduction port 19a, the atmosphere introduction passage 20, the open atmosphere valve 16, and the key hole 4a. As a result, a differential pressure is generated between the variable pressure chamber 9 and the constant pressure chamber 8, the power piston 5 moves forward, and the output shaft 25 moves forward via the valve body 4, and two pistons (not shown) of the tandem master cylinder 40 are shown. (Generally referred to as primary and secondary pistons) advances. At this time, members supported by the valve body 4 such as the valve body 12 and the vacuum valve seat member 29 move together with the valve body 4.

  Further, although the spacing member 23 is also moved forward by the advancement of the valve plunger 10, the spacing member 23 is not yet brought into contact with the reaction disk 24 by the gap C. Accordingly, since the reaction force is not transmitted from the reaction disk 24 to the spacing member 23 from the output shaft 25, this reaction force is not transmitted to the brake pedal via the valve plunger 10 and the input shaft 11. When the input shaft 11 further advances, the power piston 5 further advances, and the two pistons of the tandem master cylinder 40 further advance via the valve body 4 and the output shaft 25.

  When the loss stroke of the brake system after the tandem master cylinder 40 disappears, the negative pressure booster 1 substantially generates an output, and the tandem master cylinder 40 generates a master cylinder pressure (brake hydraulic pressure) with this output. The brake cylinders 42, 43, 44, 45 generate a braking force with this master cylinder pressure.

  At this time, the reaction disk 24 bulges back by a reaction force applied from the tandem master cylinder 40 to the output shaft 25, the gap C disappears, and the reaction disk 24 contacts the spacing member 23. As a result, the reaction force from the output shaft 25 is transmitted from the reaction disk 24 to the spacing member 23, and further transmitted to the brake pedal 39 via the valve plunger 10 and the input shaft 11 to be sensed by the driver. .

  Since the depressing speed of the brake pedal 39 during normal brake operation is not so high, the position restricting member expansion control portion 37 of the valve plunger 10 is controlled by the first and second straight lines of the vacuum valve seat member position restricting member 31. It is assumed that the first and second linear position restricting portions 31b and 31c are expanded by contacting the first and second linear position restricting portions 31b and 31c. In addition, as shown in FIG. 7A, the first and second linear position restricting portions 31b and 31c are kept in contact with the first and fourth position restricted portions 33a and 34a of the vacuum valve seat member 29. Is done. Therefore, the vacuum valve seat member 29 is held in the inoperative position shown in FIGS. 1 and 2, and the BA operation is not performed. That is, as indicated by a solid line in FIG. 8, the negative pressure booster 1 exhibits a jumping characteristic having a jumping amount Js during normal braking operation.

  The negative pressure booster 1 enters an intermediate load state after exhibiting the jumping characteristics. In this intermediate load state, when the output of the negative pressure booster 1 becomes a magnitude obtained by boosting the input of the input shaft 11 by the pedal depression force with a predetermined servo ratio SR, the atmospheric valve portion 12a is seated on the atmospheric valve seat 14. Thus, the atmospheric valve 16 is also closed to be in a balanced state (the vacuum valve 15 is already closed with the first vacuum valve portion 12b seated on the first vacuum valve seat 13). Thus, as indicated by the solid line in FIG. 8, the normal brake is operated with a braking force based on the output of the negative pressure booster 1 that has boosted the pedal depression force during the normal brake operation by the servo ratio SR.

  When the brake pedal 39 is released in order to release the normal brake from the state where both the atmospheric valve 16 and the vacuum valve 15 of the negative pressure booster 1 are closed during normal brake operation, the input shaft 11 and the valve plunger 10 is retracted together, but the valve body 4 and the vacuum valve seat member 29 are not retracted immediately because air (atmosphere) is introduced into the variable pressure chamber 9. As a result, the atmospheric valve seat 14 of the valve plunger 10 presses the atmospheric valve portion 12a of the valve body 12 backward, so that the first vacuum valve portion 12b is separated from the first vacuum valve seat 13 and the vacuum valve 15 is open. Then, the variable pressure chamber 9 communicates with the constant pressure chamber 8 via the open vacuum valve 15 and the vacuum passage 21, so that the air introduced into the variable pressure chamber 9 is opened by the open vacuum valve 15, the vacuum passage 21, the constant pressure chamber 8, and It is discharged to the vacuum source through the negative pressure inlet 27.

  As a result, the pressure in the variable pressure chamber 9 is reduced and the differential pressure between the variable pressure chamber 9 and the constant pressure chamber 8 is reduced, so that the power piston 5, the valve body 4 and the output shaft 25 are retracted by the spring force of the return spring 26. . At this time, as the valve body 4 is retracted, the vacuum valve seat member 29 and the vacuum valve seat member position restricting member 31 are also retracted integrally with the valve body 4. As the valve body 4 is retracted, the two pistons of the tandem master cylinder 40 and the output shaft 25 are also retracted by the spring force of the return spring (not shown) of the piston of the tandem master cylinder 40, and the normal brake is started to be released.

When the key member 22 comes into contact with the rear shell 3 as shown in FIGS. 1 and 2, the key member 22 stops and does not retract further. However, the valve body 4, the valve plunger 10, and the input shaft 11 are further retracted. Then, the valve plunger 10 abuts on the key member 22 and does not retreat further, and the front end of the key hole 4a of the valve body 4 abuts on the key member 22 so that the valve body 4 does not retreat further. Thus, the negative pressure booster 1 is in the initial inoperative state shown in FIGS. 1 and 2. Therefore, the master cylinder is deactivated and the master cylinder pressure disappears, and the wheel cylinder is deactivated and the braking force disappears, so that the normal brake is released.
During the normal braking operation, the second gap C2 is set, and the spacing member 23 and the valve plunger 10 are kept in a lightly connected state.

(When the first emergency brake of the negative pressure booster is activated)
When the brake pedal 39 is depressed at a first sudden depressing speed that is faster than the depressing speed at the time of normal brake operation and the first emergency brake operation is performed, the vacuum valve 15 is closed and the atmospheric valve is operated as in the case of the normal brake operation. 16 opens. As a result, the atmosphere is introduced into the variable pressure chamber 9 that is blocked from the constant pressure chamber 8. On the other hand, when the first emergency brake operation is performed, the brake pedal 39 is depressed at a relatively fast first sudden depression speed, so that the forward movement of the input shaft 11 and the valve plunger 10 with respect to the valve body 4 becomes large.

  Then, the conical outer peripheral surface of the position restricting member expansion control portion 37 of the valve plunger 10 comes into contact with the first and second linear position restricting portions 31b and 31c, and then the position restricting as the valve plunger 10 advances. The conical outer peripheral surface of the member expansion control unit 37 greatly expands the first and second linear position restriction units 31b and 31c. When the first and second linear position restricting portions 31b and 31c are greatly expanded to disengage from the first and fourth position restricted portions 33a and 34a of the vacuum valve seat member 29, the vacuum valve seat member 29 becomes a vacuum valve. The urging force of the seat member urging spring 35 moves relative to the valve body 4 rearward (that is, toward the control valve 17). Then, the second vacuum valve seat 32 at the rear end of the vacuum valve seat member 29 comes into contact with the second vacuum valve portion 12c and presses the second vacuum valve portion 12c rearward. As a result, the vacuum valve seat member 29 moves rearward and presses and moves the valve body 12 rearward, so that the atmospheric valve portion 12a of the atmospheric valve 16 moves rearward and separates from the atmospheric valve seat 14. Therefore, more air is introduced into the variable pressure chamber 9 than during normal brake operation. As shown in FIGS. 7B and 9, the first and second position restriction surfaces 31 f and 31 g of the first and second linear position restriction portions 31 b and 31 c are the second and fifth positions of the vacuum valve seat member 29. When contacting the position restricting portions 33b and 34b, the relative backward movement of the vacuum valve seat member 29 with respect to the valve body 4 is stopped, and the position of the vacuum valve seat member 29 is restricted. Thereafter, the second vacuum valve portion 12 c of the valve body 12 and the second vacuum valve seat 32 of the vacuum valve seat member 29 function as the vacuum valve 15.

  As described above, the first sudden depression speed of the brake pedal 39 when the first emergency brake is operated is such that the outer circumferential surface of the conical outer surface of the position restricting member expansion control unit 37 has the first and second linear position restricting portions 31b and 31c. The stepping speed is such that the vacuum valve seat member 29 is disengaged from the first and fourth position-restricted portions 33a, 34a but not from the second and fifth position-restricted portions 33b, 34b.

  When the reaction disk 24 bulges by the reaction force from the output shaft 25 and contacts the spacing member 23, the output of the negative pressure booster 1 becomes larger than that during normal braking operation. Therefore, as shown by a two-dot chain line in FIG. 8, the jumping amount Je1 of the jumping characteristic at the time of the first emergency brake operation becomes larger than the jumping amount Js at the time of the normal brake operation (Je1> Js). As a result, when the first emergency brake is activated, a larger braking force than that during normal braking is generated with a small pedal effort.

  Similar to the above-described normal brake operation, in the intermediate load state, the balance is achieved in the intermediate load in which both the vacuum valve 15 and the atmospheric valve 16 are closed. Thus, as indicated by the two-dot chain line in FIG. 8, the negative pressure booster 1 generates an output that boosts the pedal depression force during the first emergency brake operation with the servo ratio SR and increases with the large jumping amount Je1. The first emergency brake is activated by the braking force generated by this large output. Further, since the balance position where both the atmospheric valve 16 and the vacuum valve 15 are closed moves backward, the stroke of the input shaft 11 is shortened accordingly, and as a result, the pedal stroke is shortened. In this way, a large braking force is generated with a small pedal effort and a small pedal stroke. Thus, the first BA operation is performed during the first emergency brake operation.

When the brake pedal 39 is released to release the first emergency brake operation, the key member 22 comes into contact with the rear shell 3 and stops when the first emergency brake operation is released in the same manner as in the normal brake operation described above. However, the valve body 4, the valve plunger 10, and the input shaft 11 are further retracted. At this time, since the front ends of the first and second key member through holes 29a and 29b of the vacuum valve seat member 29 abut against the key member 22, the relative movement of the vacuum valve seat member 29 with respect to the valve body 4 is stopped. Further, the valve plunger 10 abuts against the key member 22 and does not retract further. At this time, since the valve body 4 is further retracted, the vacuum valve seat member position restricting member 31 is also retracted. As a result, the first and second linear position restricting portions 31b and 31c are separated from the second and fifth position restricted portions 33b and 34b and are located behind the first and fourth position restricted portions 33a and 34a. . Then, the first and second linear position restricting portions 31b and 31c are contracted and closed in a direction approaching each other by the elastic restoring force of the first vacuum valve seat member position restricting member 31 and the elastic restoring force of the position restricting member retainer 36. Then, the front end of the key hole 4a of the valve body 4 comes into contact with the key member 22, and the valve body 4 does not retract further. At this time, the first and second linear position restricting portions 31b and 31c are in the initial positions shown in FIG. 2 and FIG. 7 (A) in contact with the first and fourth position restricted portions 33a and 34a. Thus, the negative pressure booster 1 is in the initial inoperative state shown in FIGS. 1 and 2.
During the first emergency brake operation, the second gap C2 is set as in the case of the normal brake operation, and the distance member 23 and the valve plunger 10 are kept in a lightly connected state.

(When the second emergency brake of the negative pressure booster is activated)
When the brake pedal 39 is depressed at a second sudden depression speed that is faster than the first sudden depression speed and the second emergency brake operation is performed, the vacuum valve 15 is closed and the atmospheric valve 16 is closed as in the case of the normal brake operation. Opens. As a result, the atmosphere is introduced into the variable pressure chamber 9 that is blocked from the constant pressure chamber 8. On the other hand, when the second emergency brake operation is performed, the brake pedal 39 is depressed at a second sudden depression speed that is faster than the first sudden depression speed described above, so that the forward movement of the input shaft 11 and the valve plunger 10 with respect to the valve body 4 is the first. Even larger than when the emergency brake is activated.

  Then, the conical outer peripheral surface of the position restricting member expansion control portion 37 of the valve plunger 10 expands the first and second linear position restricting portions 31b and 31c to a greater extent than when the first emergency brake is activated. The first and second linear position restricting portions 31b and 31c are expanded more than when the first emergency brake is operated, so that the first and fourth position restricted portions 33a and 34a of the vacuum valve seat member 29 and the second and second 5. The vacuum valve seat member 29 moves away relative to the valve body 4 by the urging force of the vacuum valve seat member urging spring 35 more than the position of the first emergency brake operation. . As a result, the vacuum valve seat member 29 moves the valve body 12 more backward than when the first emergency brake is activated, so that the atmospheric valve portion 12a of the atmospheric valve 16 is separated from the atmospheric valve seat 14 more than when the first emergency brake is activated. Sit down. Therefore, more air is introduced into the variable pressure chamber 9 than when the first emergency brake is activated. As shown in FIGS. 7C and 10, the first and second position restriction surfaces 31 f and 31 g of the first and second linear position restriction portions 31 b and 31 c are the third and second positions of the vacuum valve seat member 29. When the 6-position restriction portions 33c and 34c come into contact with each other, the relative backward movement of the vacuum valve seat member 29 with respect to the valve body 4 is stopped, and the position of the vacuum valve seat member 29 is restricted. Thereafter, even when the second emergency brake is operated, the second vacuum valve portion 12c of the valve body 12 and the second vacuum valve seat 32 of the vacuum valve seat member 29 function as the vacuum valve 15 as in the case of the first emergency brake operation.

  When the reaction disk 24 bulges by the reaction force from the output shaft 25 and contacts the spacing member 23, the output of the negative pressure booster 1 becomes larger than that during the first emergency brake operation. Therefore, as shown by a dotted line in FIG. 8, the jumping amount Je2 of the jumping characteristic at the time of the second emergency brake operation becomes larger than the jumping amount Je1 at the time of the first emergency brake operation (Je2> Je1> Js). As a result, when the second emergency brake is activated, a larger brake force is generated with a smaller pedal depression force than when the first emergency brake is activated.

  At the time of the second emergency brake operation, a large amount of air is introduced into the transformer chamber 9 at a stretch. Therefore, when the jumping characteristic at the time of the second emergency brake operation is exhibited, the inside of the transformer chamber 9 is at atmospheric pressure. Therefore, at the time of the second emergency brake operation, the negative pressure booster 1 is in a full load state after jumping as shown by a dotted line in FIG. 8, and servo control of input / output after jumping is not performed. Further, since the pressure in the variable pressure chamber 9 immediately becomes atmospheric pressure, the output of the power piston 5 becomes extremely large. Therefore, the second gap C2 disappears as shown in FIG. Press forward in the direction. For this reason, the spacing member 23 is separated from the valve plunger 10, and a predetermined third gap C <b> 3 is generated between the spacing member 23 and the valve plunger 10. The other operations of the negative pressure booster 1 when the second emergency brake is activated are the same as the operations when the first emergency brake is activated. Thus, in the negative pressure booster 1 of this example, the vacuum valve seat member 29 is regulated at a plurality of different positions in the axial direction of the valve body 4 by the vacuum valve seat member position regulating member 31.

  Thus, according to the negative pressure booster 1 of this example applied to the brake booster used in the brake system 38, the vacuum valve seat member 29 is formed in a U shape from an elastic material and performs BA operation. A vacuum valve seat member position restricting member 31 that restricts the position (the axial position of the valve body 4) is provided in the valve body 4 so as not to move in the axial direction of the valve body 4. Further, the first and second vacuum valve seat member position regulating members 31 are connected to the vacuum valve seat member 29 having the second vacuum valve seat 32 on which the second vacuum valve portion 12c of the valve body 12 can be seated and performing the BA operation. The first and second vacuum valve seat member position restricting members 33 and 34 that restrict the position of the vacuum valve seat member 29 (the axial position of the valve body 4) by contacting the linear position restricting portions 31b and 31c are provided. Provided. These first and second vacuum valve seat member position restricting members 33 and 34 have three first to third positions to be brought into contact with the first and second linear position restricting portions 31b and 31c, respectively. Restricting portions 33a, 33b, 33c and three fourth to sixth position-restricting portions 34a, 34b, 34c are provided. Accordingly, the vacuum valve seat member position restricting member 31 for restricting the position of the vacuum valve seat member 29 is formed in a simple U-shape, and two BA operations are performed at the time of two emergency brake operations. The operation can be performed according to the emergency brake situation.

  Further, since the vacuum valve seat member position restricting member 31 can be formed in a simple U-shape, the assembling work of the vacuum valve seat member position restricting member 31 can be simplified and the assembly man-hour can be reduced, and the vacuum valve seat member The size management of the BA mechanisms such as 29 and the vacuum valve seat member position restricting member 31 can be simplified.

FIG. 11 is a front view similar to FIG. 3 (A) showing a vacuum valve seat member of another example of the embodiment of the negative pressure booster of the present invention, and FIG. 12 (A) is a vacuum valve seat of this example. The perspective view similar to FIG. 4 which shows a member position control member, FIG.12 (B) is sectional drawing which follows the XIIB-XIIB line | wire in FIG. 12 (A).
As shown in FIG. 11, in the vacuum valve seat member 29 of the negative pressure booster 1 of this example, the first and second vacuum valve seat member position restricting members 33 and 34 each have a stepped shape having one step. Is formed. That is, the first vacuum valve seat member position restricting member 33 includes a first position restricting portion 33a and a second position restricting portion 33b, and the second vacuum valve seat member position restricting member 34 is configured to be a fourth covered portion. It has the position control part 34a and the 5th to-be-positioned control part 34b.

  Also, as shown in FIGS. 12A and 12B, the first linear position restricting portion 31b of the vacuum valve seat member position restricting member 31 has two first and third position restricting surfaces 31f and 31h. Have. In that case, the third position restricting surface 31h is provided at the rear position in the axial direction of the valve body 4 from the position of the first position restricting surface 31f, and the first linear position restricting portion 31b has a step restricting surface with a step. Yes. Further, the second linear position restricting portion 31c of the vacuum valve seat member position restricting member 31 also has two second and fourth position restricting surfaces 31g and 31i. In that case, the fourth position restricting surface 31i is provided at a rear position in the axial direction of the valve body 4 from the position of the second position restricting surface 31g, and the second linear position restricting portion 31c has a step restricting surface with a step. Yes.

  Other configurations of the negative pressure booster 1 of this example are the same as the configurations of the negative pressure booster 1 of the above-described example. And the negative pressure booster 1 of this example is used as a brake booster of the brake system 38 shown in FIG. 6 similarly to the above-mentioned example.

  In the negative pressure booster 1 of this example configured as described above, the first vacuum valve seat member position restricting member 33 of the first vacuum valve seat member position restricting member 33 is not operated as shown in FIG. The first position restricting portion 33a contacts the first position restricting surface 31f of the first linear position restricting portion 31b, and the fourth position restricting portion 34a of the second vacuum valve seat member position restricting member 34 is the second straight line. Abuts against the second position restricting surface 31g of the shape position restricting portion 31c. Thereby, the vacuum valve seat member 29 is held at a non-operating position similar to the non-operating position of the example shown in FIG. Accordingly, the vacuum valve seat member 29 does not move during the normal brake operation as in the above example, and the negative pressure booster 1 does not perform the BA operation.

  Further, when the first emergency brake is operated, the first and second linear position restricting portions 31b and 31c are expanded as in the above example, and the first vacuum valve seat as shown in FIG. 13B. The first position restricting portion 33a of the member position restricting member 33 abuts on the third position restricting surface 31h of the first linear position restricting portion 31b, and the fourth cover of the second vacuum valve seat member position restricting member 34. The position restricting portion 34a comes into contact with the fourth position restricting surface 31i of the second linear position restricting portion 31c. That is, the vacuum valve seat member 29 moves by a predetermined amount toward the control valve 17 with respect to the valve body 4 when the first emergency brake is operated, as in the above example. Thereby, the vacuum valve seat member 29 is held at the first operating position similar to the first operating position of the example shown in FIG. 9 described above. Accordingly, the negative pressure booster 1 performs the first BA operation similar to the above-described example when the first emergency brake is operated.

Further, when the second emergency brake is operated, the first and second linear position restricting portions 31b and 31c are further expanded more than when the first emergency brake is operated, as in the above example, and FIG. As shown in FIG. 2, the second position restricting portion 33b of the first vacuum valve seat member position restricting member 33 abuts on the first position restricting surface 31f of the first linear position restricting portion 31b, and the second vacuum valve seat member. The second position restricting portion 34b of the position restricting member 34 contacts the second position restricting surface 31g of the second linear position restricting portion 31c. That is, the vacuum valve seat member 29 moves further toward the control valve 17 with respect to the valve body 4 when the second emergency brake is operated than when the first emergency brake is operated, as in the above example. Thereby, the vacuum valve seat member 29 is held at the second operating position similar to the second operating position of the example shown in FIG. Therefore, the negative pressure booster 1 performs the second BA operation similar to the above-described example when the second emergency brake is operated.
The other operations of the negative pressure booster 1 of this example are the same as the operations of the negative pressure booster 1 of the above example.

According to the negative pressure booster 1 of this example, the first and third position restricting surfaces 31f.31h are respectively provided on the first and second linear position restricting portions 31b and 31c of the vacuum valve seat member position restricting member 31. And second and fourth position restricting surfaces 31g.31i are provided. The first and second vacuum valve seat member position restriction members 33 and 34 include two first and second position restriction portions 33a and 33b and two fourth and fifth position restriction portions, respectively. 34a and 34b are provided. The combination of contact between the first and third position restricting surfaces 31f.31h and the first and second position restricted portions 33a and 33b, and the second and fourth position restricting surfaces 31g.31i and the fourth and fourth positions. By the combination of contact with the five position restricting portions 34a and 34b, three BA operations can be performed at the time of three emergency brakes as in the above-described example. The first and second linear position restriction portions 31b and 31c are provided with two first and third position restriction surfaces 31f.31h and second and fourth position restriction surfaces 31g.31i, respectively. Thus, the number of position restricting portions of the first and second vacuum valve seat member position restricting members 33 and 34 provided in the vacuum valve seat member 29 can be reduced from the above example. As a result, the configuration of the vacuum valve seat member 29 and the first and second vacuum valve seat member position restricting members 33 and 34 can be simplified.
Other functions and effects of the negative pressure booster 1 in this example are the same as those in the above example.

  The present invention is not limited to the above-described embodiments, and various design changes can be made based on the present invention described in the claims. For example, in the negative pressure booster 1 of each of the above-described examples, both the first and second BA operations in the first and second emergency brake operations are performed. It is also possible to perform three or more BA operations such as a third BA operation indicated by a one-dot chain line.

In each of the above-described examples, the present invention is applied to a single negative pressure booster having one power piston 5, but the present invention is a tandem negative pressure booster having a plurality of power pistons 5. It can also be applied to a device.
Furthermore, in the above-described example, the negative pressure booster of the present invention is applied to the brake system, but it can be applied to other systems and devices using the negative pressure booster.

  The negative pressure booster (brake booster) according to the present invention obtains a larger output (brake force) than during normal operation with the same input (brake operating force) as during normal operation during operation assist (emergency brake operation). Therefore, it can be suitably used for a negative pressure booster (brake booster).

DESCRIPTION OF SYMBOLS 1 ... Negative pressure booster, 2 ... Front shell, 3 ... Rear shell, 4 ... Valve body, 5 ... Power piston, 8 ... Constant pressure chamber, 9 ... Variable pressure chamber, 10 ... Valve plunger, 11 ... Input shaft, 12 ... Valve body, 12a ... atmospheric valve portion, 12b ... first vacuum valve portion, 12c ... second vacuum valve portion, 13 ... first vacuum valve seat, 14 ... atmospheric valve seat, 15 ... vacuum valve, 16 ... atmospheric valve, 17 ... Control valve, 22 ... Key member, 23 ... Spacing member, 24 ... Reaction disk, 25 ... Output shaft, 29 ... Vacuum valve seat member, 31 ... Vacuum valve seat member position restricting member, 31b ... First linear position restricting portion , 31c: second linear position restricting portion, 31f: first position restricting surface, 31g ... second position restricting surface, 31h ... third position restricting surface, 31i ... fourth position restricting surface, 32 ... second vacuum valve seat 33 ... first vacuum valve seat member position restriction member, 33a ... first position Control part, 33b ... 2nd position restriction part, 33c ... 3rd position restriction part, 34 ... 2nd vacuum valve seat member position restriction member, 34a ... 4th position restriction part, 34b ... 5th position restriction 34c ... sixth position restricting part, 35 ... vacuum valve seat member biasing spring, 37 ... position restricting member expansion control part, 38 ... brake system, 39 ... brake pedal, 40 ... tandem master cylinder, 42, 43 , 44,45 ... Brake cylinder

Claims (5)

A valve body arranged to be movable back and forth with respect to the inside of the housing, and arranged so as to be relatively movable with respect to the valve body, moved by an input from the input shaft to close the vacuum valve and open the atmospheric valve into the housing. A valve plunger for introducing air and an air generated in the housing generate an output in response to the input, and the operation assist mechanism operates to increase the output from the normal operation when the operation assist mechanism does not operate. In the negative pressure booster,
The operation assist mechanism is movably provided on the valve body, and does not move the atmospheric valve relative to the valve body when not activated, and has a jumping amount that moves when activated and starts generating an output with respect to the input. A vacuum valve seat member for operating the atmospheric valve so as to increase from a jumping amount during normal operation, a vacuum valve seat member urging means for constantly urging the vacuum valve seat member toward the atmospheric valve, and the valve body A U-shaped vacuum valve seat member position regulating member which is provided on the vacuum valve seat member to regulate the position of the valve body in the axial direction of the valve body and which can be elastically expanded, and the vacuum valve seat member. A vacuum valve seat member position restricting member in which an axial position of the valve body of the vacuum valve seat member is regulated by contacting the vacuum valve seat member position restricting member, and the valve plan A position restricting member expansion control unit that opens the vacuum valve seat member position restricting member and activates the vacuum valve seat member when the input shaft is operated at a higher operating speed than normal operation. With
The vacuum valve seat member position restriction member is a plurality of position restriction members that respectively regulate a plurality of different positions of the valve body in the axial direction of the valve body by contacting the vacuum valve seat member position restriction member. A negative pressure booster comprising at least a portion.   2. The negative pressure booster according to claim 1, wherein the vacuum valve seat member position restricting member has a predetermined number of steps for setting the plurality of position restricting portions.   The negative pressure booster according to claim 1, wherein the vacuum valve seat member position restricting member has a plurality of position restricting surfaces that can selectively contact the plurality of position restricting portions. .   4. The negative pressure booster according to claim 3, wherein the vacuum valve seat member position restricting member has a predetermined number of steps for setting the plurality of position restricting surfaces. In the brake booster that outputs the braking force obtained by boosting the brake operating force with the negative pressure booster,
The negative pressure booster is the negative pressure booster according to any one of claims 1 to 4,
The brake booster, wherein the operation assist mechanism is a brake assist mechanism that operates when an emergency brake is operated and outputs a larger brake force with the same brake operation force than when a normal brake is operated.

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