JP3736699B2 - Booster - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a booster used for a brake of an automobile, and more specifically, when the depression force (input) of a brake pedal becomes a predetermined value or more.So that a large output is obtained. InThe present invention relates to a configured booster.
[0002]
[Prior art]
Conventionally, a booster having the following configuration is known.
That is, a substantially cylindrical valve body that is slidably provided in the shell, a valve plunger that is slidably fitted to the valve body and interlocked with the input shaft, and a base portion that is located on the rear side includes the valve body. A booster including an output shaft slidably attached to the base plate and a reaction disk provided between the base of the output shaft and the front end surface of the valve plunger is known (for example, Japanese Patent Laid-Open No. Hei 8- 85442).
In the above-described conventional device, the servo ratio is increased in a state where the input is larger than in a state where the input is small after the operation of the booster is started, so that a good brake feeling is achieved in a state where the input is small. At the same time, sufficient output can be obtained even when a large braking force such as emergency braking is required.
[0003]
[Problems to be solved by the invention]
By the way, the booster disclosed in the above publication is configured such that the servo ratio is large when the input is large. However, in order to obtain an output in the operating region where the servo ratio is large, the input is naturally large. There is a need to. For this reason, for example, when a large braking force such as an emergency brake is required, if the driver is a weak woman or the like, the pedaling force (input) of the brake pedal is small, so the output of the booster that is necessary as an emergency brake May not be obtained.
[0004]
[Means for Solving the Problems]
  In view of the circumstances described above, in the invention of claim 1, a substantially cylindrical valve body slidably provided in the shell, and a valve plunger slidably fitted to the valve body and interlocked with the input shaft, A booster comprising: an output shaft having a base portion located on the rear side slidably attached to the valve body; and a reaction disk provided between the base portion of the output shaft and a front end surface of the valve plunger. In
While forming a gap between the rear side end face of the output shaft and the valve body,When the input of the input shaft exceeds a predetermined value,Above output shaftRear end face ofAnd the above valve body abut,Increased reaction force transmitted to the input shaftIt is configured not to do so.
  Claims5In the invention ofA generally cylindrical valve body slidably provided in the shell, a valve plunger that is slidably fitted to the valve body and interlocked with the input shaft, and a base located on the rear side are slid onto the valve body. In a booster comprising an output shaft movably attached and a reaction disk provided between the base of the output shaft and the front end face of the valve plunger,
A gap is formed between the rear end face of the output shaft and the valve body, and a contact member that contacts the reaction disk is slidably provided on the output shaft, and the contact member and the output shaft When the input of the input shaft reaches a predetermined value or more, the contact member is moved against the spring by the reaction disk, and the rear end surface of the output shaft and the valve Configured so that the reaction force transmitted to the input shaft does not increase due to contact with the bodyIs.
[0005]
[Action]
  According to the configuration of the first aspect, in a state in which the depression force (input) of the brake pedal is small after the operation of the booster is started, the output reaction force acting on the output shaft is in contact with the reaction disk at the base portion, Further, since the reaction disc is transmitted to the valve plunger, an output with a predetermined servo ratio can be obtained as in the conventional general booster.
  On the other hand, when the depression force (input) of the brake pedal is equal to or higher than the predetermined value after the operation of the booster is started,The rear end face of the output shaft and the valve body come into contact with each other so that the reaction force transmitted to the input shaft does not increase.. In other words, the reaction force is not transmitted to the driver via the brake pedal, so that when the input (braking force of the brake pedal) exceeds the predetermined value, the booster immediately becomes the full load point and a large output can be obtained.
  Therefore, when a large braking force is required as in an emergency brake, a large output can be reliably obtained even if the driver is a weak woman.
  Therefore, the safety at the time of brake operation can be improved as compared with the prior art.
  In addition, the above claims5With this configuration, in the state where the depression force (input) of the brake pedal is small after the operation of the booster is started, the output reaction force acting on the output shaft is in contact with the reaction disk at the base, and further the reaction disk Therefore, an output with a predetermined servo ratio can be obtained in the same manner as a general booster.
  On the other hand, when the depression force (input) of the brake pedal becomes equal to or higher than the predetermined value after the operation of the booster is started, the contact member is moved against the spring by the reaction disk.Furthermore, the rear end surface of the output shaft and the valve body come into contact with each other, so that the reaction force transmitted to the input shaft does not increase. In other words, the reaction force is not transmitted to the driver via the brake pedal, so that when the input (braking force of the brake pedal) exceeds the predetermined value, the booster immediately becomes the full load point and a large output can be obtained.
Further, at this time, the pedaling force required for the rear end face of the output shaft and the valve body to contact each other can be easily changed by a spring mounted between the contact member and the output shaft.
  Therefore, when a large braking force is required as in an emergency brake, a large output can be reliably obtained even if the driver is a weak woman.
  Therefore, the safety at the time of brake operation can be improved as compared with the prior art.
[0006]
【Example】
(First embodiment)
The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, the inside of a sealed container composed of a front shell 1 and a rear shell 2 is divided into a front chamber 4 and a rear chamber 5 by a center plate 3 provided at the center thereof. is doing.
A valve body 6 formed in a substantially cylindrical shape is slidably passed through the shaft portions of the center plate 3 and the rear shell 2 while maintaining airtightness by seal members 7 and 8.
A front power piston 11 and a rear power piston 12 housed in the front chamber 4 and the rear chamber 5 are connected to the valve body 6, respectively, and a front diaphragm 13 and a rear diaphragm 14 are connected to the rear surfaces of the power pistons 11 and 12. Are stretched. Thus, a constant pressure chamber A and a variable pressure chamber B are formed before and after the front diaphragm 13, and a constant pressure chamber C and a variable pressure chamber D are formed before and after the rear diaphragm 14.
A valve mechanism 15 for switching the flow path between the two constant pressure chambers A and C, the two variable pressure chambers B and D, and the atmosphere is provided in the valve body 6. The valve mechanism 15 includes an annular vacuum valve seat 16 formed on the inner peripheral surface of the valve body 6 and an annular vacuum valve formed on the right end of a valve plunger 17 slidably provided on the valve body 6 inside the vacuum valve seat 16. And a valve body 22 seated on both the valve seats 16 and 18 from the rear side by the elastic force of the spring 21.
A vacuum valve 23 is configured by the vacuum valve seat 16 and the seat portion of the valve body 22 contacting and separating from the vacuum valve seat 16, and a space outside the vacuum valve 23 includes a first constant pressure passage 24 formed in the valve body 6, The constant pressure chambers A and C are communicated with each other via a second constant pressure passage 25 formed outside the first constant pressure passage 24. The constant pressure chamber A communicates with an intake manifold of an engine (not shown) through a negative pressure introduction pipe 26.
On the other hand, the atmospheric valve 27 is constituted by the atmospheric valve seat 18 and the seat portion of the valve body 22 that is in contact with and separated from the atmospheric valve seat. The space between the atmospheric valve 27 and the vacuum valve 23 is a radius formed in the valve body 6. The variable pressure chamber D is communicated with the variable pressure chamber D via the first variable pressure passage 28 in the direction, and the variable pressure chamber D is further communicated with the variable pressure chamber B via the second variable pressure passage 31 formed in the axial direction of the valve body 6. Further, the space inside the atmospheric valve 27 communicates with the atmosphere via the atmospheric passage 32, and a filter 33 is provided in the atmospheric passage 32.
An input shaft 34 is pivotally connected to the rear end portion of the valve plunger 17, and a terminal portion of the input shaft 34 is connected to a brake pedal (not shown). On the other hand, a rubber reaction disk 35 is disposed on the front side of the valve plunger 17, and this reaction disk 35 is housed in a recess 36 a formed in a base portion 36 A of the output shaft 36. Note that a key member 37 is engaged with the valve plunger 17, thereby preventing the valve plunger 17 from falling off the valve body 6.
An annular protrusion 6A that protrudes toward the front side is provided on the inner peripheral part of the valve body 6, and the concave part 36a of the output shaft 36 is slidably fitted on the outer peripheral part. The reaction disk 35 in the recess 36a is interposed between the bottom of the recess 36a and the end surface of the annular protrusion 6A.
A front side end portion of the output shaft 36 protrudes outward from the shaft portion of the front shell 1 and is interlocked with a piston of a master cylinder (not shown).
Further, a return spring 38 is mounted between the valve body 6 and the front shell 1, so that the non-operating valve body 6 and the like are in the illustrated non-operating position where the key member 37 contacts the wall surface of the rear shell 2. It has stopped. In this inoperative state, the vacuum valve 23 is opened, while the atmospheric valve 27 is closed. Therefore, the constant pressure chambers A and C communicate with the variable pressure chambers B and D, and negative pressure is introduced into each of the chambers.
[0007]
The above configuration is not different from that of a conventionally known brake booster.
Thus, in this embodiment, when the brake pedal depressing force (input) becomes a predetermined value or more after the brake booster is operated, the full load point is quickly improved.
That is, as shown in FIG. 2 in an enlarged manner, an annular disc spring 41 is fitted on the annular projection 6A on the rear side of the rear end 36b of the output shaft 36. The disc spring 41 is brought into contact with the end surface of the end portion 36b of the output shaft 36 from the rear side. When the brake booster shown in FIGS. 1 and 2 is in an inoperative state, the rear end of the disc spring 41 in the natural state, and the stepped end surface 6B of the valve body 6 as a stopper portion opposed thereto are provided. In the meantime, the gap δ is maintained.
With such a configuration, after the brake booster is operated, when the depression force (input) of the brake pedal exceeds a predetermined value, the gap δ is eliminated, and the disc spring 41 and the stepped end surface 6B are Then, the disc spring 41 sandwiched between the rear end 36b of the output shaft 36 and the stepped end surface 6B of the valve body 6 comes to be compressed to a minimum, and after that time, The reaction force of the output acting on the output shaft 36 is not transmitted to the valve plunger 17 (state shown in FIG. 3).
In the present embodiment, a space formed by the annular groove 6b is formed on the end surface 6a of the annular protrusion 6A that is in contact with the rear end surface of the reaction disk 35. By providing the annular groove 6b, a part of the reaction disk 35 that is elastically deformed as the brake booster is operated is filled in the annular groove 6b (FIG. 3). State). Thus, the relative displacement amount when the base portion 36A of the output shaft 36 slides on the outer peripheral portion of the annular protrusion 6A toward the stepped end surface 6B is made as large as possible.
[0008]
(Description of operation)
In the above configuration, when the brake pedal (not shown) is depressed from the non-actuated state of the brake booster shown in FIGS. 1 to 2 and the input shaft 34 and the valve plunger 17 linked thereto are advanced, the vacuum valve 23 is moved. While being closed, the atmospheric valve 27 is opened. As a result, the atmosphere is introduced into each of the variable pressure chambers B and D, and the valve body 6 and the output shaft 36 and the like are generated by the differential pressure between the negative pressure in the constant pressure chambers A and C and the atmospheric pressure in the variable pressure chambers B and D. Is moved forward. That is, the brake booster is activated.
When the brake booster is operated in this way, the reaction disc 35 is compressed in the axial direction by the reaction force of the output acting on the output shaft 36, so that the shaft portion on the rear side faces the rear side. It bulges out and comes into contact with the front end surface 17a of the valve plunger 17. In the initial stage of the operation of the brake booster, since the depression force (input) of the brake pedal is small, the reaction disk 35 is not filled in the annular groove 6b, and the shaft of the output shaft 36 with respect to the annular protrusion 6A Since the relative movement amount in the direction is also small, the rear end portion of the disc spring 41 is separated from the stepped end surface 6B as the stopper portion.
Therefore, at the time of jumping indicated by P in FIG. 4, that is, after the above-described reaction disk 35 contacts the front end surface 17 a of the valve plunger 17, the sectional area of the valve plunger 17 and the reaction disk 35 contact. Valve body6The output is increased by a predetermined servo ratio determined by the cross-sectional area of the annular projection 6A.
A part of the elastically deformed reaction disk 35 is filled in the annular groove 6b as the pedal effort (input) of the brake pedal increases after the operation of the brake booster described above starts (see FIG. 3). . Further, after that, when the depression force (input) of the brake pedal becomes larger than a predetermined value, the rear end of the disc spring 41 is accompanied by the relative movement of the output shaft 36 toward the axial rear side with respect to the annular protrusion 6A. The portion comes into contact with the stepped end surface 6B of the valve body 6 as a stopper portion (see FIG. 3). This time is the time indicated by Q in FIG. 4, and the reaction force of the output acting on the output shaft 36 from this time is transmitted to the valve body 6 via the disc spring 41. Then, the reaction force transmitted to the valve plunger 17 is reduced by that amount. Therefore, compared to the servo ratio between P and Q, a large servo ratio indicated by a solid line is indicated after the point indicated by Q. Increases the output.
Thus, while the disc spring 41 is compressed to the minimum by the end portion 36b of the output shaft 36 and the step end surface 6B, the output increases with this large servo ratio, but the disc spring 41 is compressed to the minimum. Then, since the disc spring 41 and the base portion 36aA of the output shaft 36 function as a substantially integral body, all the reaction force of the output acting on the output shaft 36 is applied to the step end surface 6B (valve body 6). It will be transmitted and will not be transmitted to the valve plunger 17 (FIG. 3). That is, as shown in FIG. After this total load point R, the output and the input increase at a ratio of 1: 1 as is well known in the art.
Since the time required until the disc spring 41 is compressed to the minimum after the end on the rear side of the disc spring 41 contacts the stepped end surface 6B is extremely short, the end on the rear side of the disc spring 41 When it comes into contact with the stepped end surface 6B, the full load point R is quickly reached.
As described above, in this embodiment, when the depression force (input) of the brake pedal exceeds a predetermined value, the reaction force of the output acting on the output shaft 36 is not transmitted to the driver, so that the full load point R is quickly reached. It is configured. Therefore, for example, in the case of an emergency brake or the like that requires a large braking force, the driver is a weak woman or the like, and a large output can be reliably obtained with a small input. Therefore, the safety at the time of brake operation can be improved as compared with the prior art.
Further, according to the above-described configuration, the reaction disk 35 is compressed by the base portion 36A of the output shaft 36 and the annular protrusion 6A of the valve body 6 and the time during which the reaction disk 35 is compressed is less than that of the conventional one. A relatively inexpensive rubber can be used as the material of the disk 35. Therefore, the cost of the reaction disk 35 can be reduced, and as a result, the cost of the brake booster can be reduced.
Furthermore, when the brake booster is operated in the initial region after the start of the operation of the brake booster from P to Q in FIG. Since the output increases at the same servo ratio as the booster, the driver's brake feeling is not deteriorated in the low and medium speed ranges.
[0009]
(Second embodiment)
Next, FIG. 5 shows a second embodiment of the present invention. In the second embodiment, the outer peripheral portion of the front side end portion of the annular protrusion 6A of the valve body 6 is reduced in diameter, whereby the stepped end surface 6B as a stopper portion is provided at the rear end portion of the reduced diameter portion. Is forming. On the other hand, the inner peripheral surface of the rear side end portion of the recess 36a of the output shaft 36 is expanded to form a stepped end surface 36c facing the stepped end surface 6B. In a non-actuated state shown in the figure, the disc spring 41 is brought into contact with the stepped end surface 36c, and a gap is formed between the rear end of the disc spring 41 and the stepped end surface 6B as a stopper portion opposed thereto. Is maintained. With this configuration, the front inner peripheral surface adjacent to the stepped end surface 36c of the recess 36a is fitted to the small diameter portion of the front end of the annular protrusion 6A, and the recess 36a The inner peripheral surface on the rear side of the stepped end surface 36c is fitted to the outer peripheral portion of the original annular protrusion 6A.
Other configurations are the same as those in the first embodiment. Even in the second embodiment, it is possible to obtain the same operations and effects as the first embodiment described above.
[0010]
(Third embodiment)
Next, FIG. 6 shows a third embodiment of the present invention. In this third embodiment, the base of the output shaft 3636A flange portion 36c extending radially outward is formed on the outer peripheral portion of the front side end portion in A, and a disc spring 41 is brought into contact with the rear end surface 36c 'of the flange portion 36c from the rear side. In the third embodiment, the annular protrusion36A stepped end surface 6B formed at the front side of the position A and facing the disc spring 41 is used as a stopper portion. In the non-actuated state, a gap is maintained between the stepped end surface 6B serving as the stopper and the disc spring 41. In the third embodiment, no annular groove is provided on the end face of the annular protrusion 6a. Other configurations are the same as those in the first embodiment. Even in the third embodiment, the same operations and effects as those of the first embodiment described above can be obtained.
[0011]
(Fourth embodiment)
In the above-described three embodiments, the disc spring 41 is brought into contact with the end surface formed on the base portion 36A of the output shaft 36 from the rear side, and the disc spring 41 and the stepped end surface as a stopper portion facing the disc spring 41 in the non-operating state. Although the gap δ is maintained with respect to 6B, a configuration in which the disc spring 41 in each of the above embodiments is omitted as a fourth embodiment of the present invention may be used (the drawing is omitted). In this case, an end surface (36c, 36c ′, an end surface of the rear end portion 36b) formed on the base portion 36A of the output shaft 36 in a state of being opposed to each other, and a stepped end surface on the valve body 6 side facing it. A stopper portion is formed by 6B. In this case, when the pedal effort (input) of the brake pedal becomes equal to or greater than a predetermined value after the operation of the brake booster device is started, end surfaces (36c, 36c ′ on the base portion 36A side of the output shaft 36, end portions 36b on the rear side). The end surface of the valve body 6 comes into contact with the stepped end surface 6B on the valve body 6 side, and at this point (at the time indicated by Q in FIG. 4), all the reaction force of the output acting on the output shaft 36 is the stepped end surface 6B (valve body). 6) and no longer transmitted to the valve plunger 17. Therefore, in this case, as indicated by a broken line in FIG. Even in the fourth embodiment, it is possible to obtain the same operations and effects as the above-described embodiments.
In the first and second embodiments described above, the end face 6a of the annular protrusion 6A of the valve body 6 is formed with an annular groove 6b, whereby the relative movement amount in the axial direction between the output shaft 36 and the annular protrusion 6A. However, the annular groove 6b may be omitted.
[0012]
(5th Example)
Next, FIG. 7 shows a fifth embodiment of the present invention. In the fifth embodiment, the disc spring 41 and the annular groove 6a of the annular protrusion 6A in the first embodiment shown in FIG. 2 are omitted, while the base portion 36A of the output shaft 36 is improved.
That is, in the fifth embodiment, a stepped recess 36c is formed in the base portion 36A of the output shaft 36, which is continuous from the bottom 36a 'of the recess 36a in which the reaction disk 35 is accommodated. The stepped recess 36c has a small diameter on the rear side and a large diameter on the front side. A cylindrical contact member 45 that is short in the axial direction is slidably fitted in the stepped recess 36c, and the front end surface of the contact member 45 and a stepped step opposite thereto are provided. A spring 46 set at a predetermined set load is mounted over the bottom of the recess 36c. In the non-actuated state, the abutting member 45 is stopped at the most rear side position of the stepped recess 36 c by the elastic force of the spring 46. At this time, the rear end face of the abutting member 45 and the bottom of the recess 36 a are located on the same plane, and these places are in contact with the end face of the reaction disk 35. Further, a gap δ is maintained between the end face of the rear end portion 36b of the output shaft 36 and the stepped end face 6B. Other configurations are the same as those of the first embodiment shown in FIG. In the fifth embodiment, the end surface 36b on the rear side of the output shaft 36 and the end surface 6B of the step portion respectively constitute a stopper portion.
In the fifth embodiment configured as described above, when the brake pedal is depressed and the brake booster is operated, the reaction disk 35 is compressed in the axial direction by the output shaft 36 and the end surface of the annular protrusion 6A. The shaft portion bulges to the rear side and contacts the front end surface 17a of the valve plunger 17. At the time of this jumping (time indicated by P in FIG. 4), the spring 46 is not compressed, and the end surface of the rear end portion 36b of the output shaft 36 is separated from the stepped end surface 6B. When the input of the brake pedal becomes equal to or greater than a predetermined value after this jumping, the shaft portion on the front side of the elastically deformed reaction disk 35 bulges to the front side, and abuts against the elastic force of the spring 46. 45 is moved to the front side in the stepped recess 36c.(Time point Q in FIG. 4). After the base portion 36A of the output shaft 36 approaches the stepped end surface 6B, the end surface of the rear side end portion 36b contacts the stepped end surface 6B. So thisAfterThe reaction force acting on the output shaft 36 is all transmitted to the step end surface 6B and is not transmitted to the valve plunger 17 at all. Therefore, as soon as the stepped end surface 6B and the rear end 36b of the output shaft 36 abut,Full load point.
Therefore, the same effects as those of the above-described embodiments can be obtained by the configuration of the fifth embodiment.
[0013]
(Sixth embodiment)
Next, FIG. 8 shows a sixth embodiment of the present invention. In the sixth embodiment, the configuration of the base portion 36A of the output shaft 36 in the fifth embodiment is different.
That is, in the sixth embodiment, a concave portion 36c having the same inner diameter as that of the concave portion 36a and continuous from the concave portion 36a is formed at the bottom of the concave portion 36a of the output shaft 36, and the continuous concave portions 36a and 36c are formed therein.As a contact memberA cup-shaped sleeve 51 is slidably fitted. A spring 46 set to a predetermined set load is mounted over the bottom 51a of the sleeve 51 and the bottom 36d of the recess 36c facing the sleeve 51. As a result, the sleeve 51 is always biased toward the rear side in the recesses 36a and 36c. A snap ring 52 is attached at a position near the rear end of the recess 36 a of the output shaft 36, and the rear end of the sleeve 51 is brought into contact with the snap ring 52. This restricts the position of the rear end of the sleeve 51 in the recesses 36a and 36c.
In this embodiment, the reaction disk 35 is accommodated in the sleeve 51, and the inner peripheral portion on the rear side of the sleeve 51 and the inner peripheral portion of the snap ring 52 in this state are connected to the annular protrusion 6A of the valve body 6. A reaction disc 35 is interposed between the bottom of the sleeve 51 and the end face 6a of the annular protrusion 6A. Since the sleeve 51 is fitted to the annular projection 6A, the recess 36a of the output shaft 36 is also fitted to the sleeve 51 so that the sleeve 51 can be moved to the annular projection 6A. A gap is maintained between the end surface of the rear side end portion 36b and the stepped end surface 6B opposed thereto.
Other configurations are the same as those of the fifth embodiment. Also in the sixth embodiment, when the brake pedal depressing force (input) exceeds a predetermined value after the operation of the brake booster is started, the spring 46 is compressed and the base portion 36A of the output shaft 36 is directed toward the stepped end surface 6B. By being moved, the end face of the rear end 36b of the output shaft 36 comes into contact with the stepped end face 6B. All of the reaction force of the output acting on the output shaft 36 from this time (Q in FIG. 4) is transmitted to the step end surface 6B (valve body 6) and is not transmitted to the valve plunger 17. Therefore, at this time, the full load point is reached immediately (time R ′ in FIG. 4). Therefore, also in the sixth embodiment, it is possible to obtain the same effect as that of the fifth embodiment described above.
Moreover, in the fifth and sixth embodiments, the time when the end surface 36b on the rear side of the output shaft 36 abuts against the stepped end surface 6B (time point Q in FIG. 4) It can be easily changed by changing the set load.
[0014]
In each of the above-described embodiments, the case where the present invention is applied to a tandem type brake booster has been described. However, a single type brake booster or three sets of constant pressure chambers and variable pressure chambers are provided in the shell 1. The present invention can also be applied to a triple type booster.
[0015]
【The invention's effect】
As described above, according to the present invention, when a large braking force is required as in an emergency brake, an effect that a driver is a weak woman and can surely obtain a large output can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is an enlarged view of a main part of FIG.
3 is a cross-sectional view showing a state after the operation of each member shown in FIG. 2;
FIG. 4 is a diagram showing a relationship between input and output of the brake booster shown in FIG. 1;
FIG. 5 is a sectional view showing a second embodiment of the present invention.
FIG. 6 is a sectional view showing a third embodiment of the present invention.
FIG. 7 is a sectional view showing a fifth embodiment of the present invention.
FIG. 8 is a sectional view showing a sixth embodiment of the present invention.
[Explanation of symbols]
1 ... Front shell 2 ... Rear shell
6 ... Valve body 6B ... Step part end face (stopper part)
17 ... Valve plunger 35 ... Reaction disc
36 ... Output shaft 36b ... End (stopper)

Claims (8)

A generally cylindrical valve body slidably provided in the shell, a valve plunger that is slidably fitted to the valve body and interlocked with the input shaft, and a base located on the rear side are slid onto the valve body. In a booster comprising an output shaft movably attached and a reaction disk provided between the base of the output shaft and the front end face of the valve plunger,
And forming a gap between the rear end face and the valve body of the output shaft, the input of the input shaft is equal to or greater than a predetermined value, the rear end face of the output shaft and the said valve body is in contact with the input A booster characterized in that the reaction force transmitted to the shaft does not increase .   An annular protrusion that protrudes toward the front side is formed on the inner peripheral portion of the valve body, and a recess is formed at the base of the output shaft, and the reaction disk is accommodated in the recess, and The booster according to claim 1, wherein the recess is movably fitted to the annular protrusion of the valve body. The rear end face of the output shaft from its rear side Yes abut against a spring, that the input of the input shaft becomes a predetermined value or more Barububode I with respect to the spring is configured to abut The booster according to claim 1 or 2, characterized by the above. The reaction disk is interposed between the valve body and the output shaft,
The booster according to any one of claims 1 to 3, wherein an annular groove in which a part of the reaction disk is filled is formed on an end surface of the valve body with which the reaction disk contacts. A generally cylindrical valve body slidably provided in the shell, a valve plunger that is slidably fitted to the valve body and interlocked with the input shaft, and a base located on the rear side are slid onto the valve body. In a booster comprising an output shaft movably attached, and a reaction disk provided between the base of the output shaft and the front end face of the valve plunger,
  A gap is formed between the rear end face of the output shaft and the valve body, and a contact member that contacts the reaction disk is slidably provided on the output shaft. The contact member and the output shaft When the input of the input shaft exceeds a predetermined value, the contact member is moved against the spring by a reaction disk, and the rear end face of the output shaft and the valve A booster characterized in that the reaction force transmitted to the input shaft does not increase due to contact with the body. 6. The booster according to claim 5, wherein a concave portion is formed in a base portion of the output shaft, and the contact member, the spring, and the reaction disk are accommodated in the concave portion. An annular protrusion is formed on the valve body so as to protrude toward the front side, and a stepped recess whose rear side is reduced in diameter continuously from the recess is formed at the bottom of the recess formed at the base of the output shaft. The contact member is slidably fitted in the stepped recess, and the reaction disk contacts the rear side of the contact member. The booster according to claim 6, wherein the spring is elastically mounted between the bottom portion and the annular protrusion is slidably fitted in the concave portion of the base portion. An annular protrusion is formed on the valve body so as to protrude toward the front side, and the contact member is formed in a bottomed cylindrical shape, and the contact member is slid into a recess formed in a base portion of the output shaft. The reaction disk is housed in the recess of the contact member, and the spring is elastically mounted between the bottom of the contact member and the recess bottom of the output shaft facing the contact member. The booster according to claim 6 , wherein the annular protrusion is slidably fitted in the recess of the contact member.

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