JPH1059164A - Booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve actuation responsiveness of a brake booster at the time of quick braking. SOLUTION: A small circular groove 8b is formed at a specified position in an axial direction in an outer circumferential part of a valve plunger 8, and a circular elastic member 27 is installed there. When a brake pedal is quickly stepped, the elastic member 27 provided on the valve plunger 8 is engaged in an inner circumferential part of a valve body 2. By slide resistance of the elastic member 27, the valve plunger 8 being pushed to the rear side to return to the valve body 2 is temporarily prohibited. Opening of a breather valve positioned on the rear side of the valve plunger 8 can thus be maintained large. Open air can therefore be introduced into a pressure change chamber B speedily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a booster used for a brake of an automobile or the like, and more particularly, to a booster having a good operation response at the time of sudden braking.

[0002]

2. Description of the Related Art Conventionally, the following brake booster is known. That is, a substantially cylindrical valve body slidably provided in a shell, a power piston provided on an outer peripheral portion of the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston. And a valve mechanism for controlling the opening and closing of a flow path between the constant pressure chamber, the variable pressure chamber, and the atmosphere, the valve mechanism comprising: a vacuum valve seat formed on an inner peripheral portion of a valve body; A valve plunger slidably fitted to the body and interlocking with the input shaft; an air valve seat formed on the valve plunger located inside the vacuum valve seat; and an air valve seat formed on the valve plunger; Brake boosters having a valve seat that sits on a valve seat are known. In such a conventional brake booster, in the non-operating state, the valve body is seated on the atmospheric valve seat and is separated from the vacuum valve seat, whereby the constant pressure chamber and the variable pressure chamber communicate with each other, Negative pressure is introduced into both chambers. Then, when the brake pedal is depressed from this inoperative state, the input shaft and the valve plunger interlocked with it are advanced, and the valve body is seated on the vacuum valve seat and is separated from the atmospheric valve seat. Thus, the communication between the constant pressure chamber and the variable pressure chamber is prevented, and the atmosphere is introduced into the variable pressure chamber. Therefore, the valve body and the like are advanced by the differential pressure between the negative pressure in the constant pressure chamber and the atmosphere in the variable pressure chamber, and an output of a predetermined servo ratio is obtained from the output shaft.

[0003]

The following disadvantages have been pointed out in the conventional brake booster described above. That is, at the time of sudden braking when the brake pedal is suddenly depressed, the valve plunger interlocked with the brake pedal is also rapidly advanced. In this case, while the valve element is separated from the atmospheric valve seat as described above, the air is introduced into the variable pressure chamber while sitting on the vacuum valve seat,
The reaction force of the output acting on the output shaft increases, and the reaction force is transmitted to the valve plunger via the reaction disk.
Therefore, the valve plunger is pushed back toward the rear side relative to the valve body. As described above, when the valve plunger is pushed back, the atmospheric valve seat provided on the valve plunger is pushed back toward the valve body, and the amount of separation between the atmospheric valve seat and the valve body decreases, and The amount of air introduced into the system is reduced. Therefore, in the conventional brake booster, it has been pointed out that the operation responsiveness at the time of sudden braking is poor.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a substantially cylindrical valve body slidably provided in a shell, a power piston provided on an outer peripheral portion of the valve body, and A constant pressure chamber and a variable pressure chamber formed before and after the power piston; and a valve mechanism provided in the valve body for controlling opening and closing of a flow path between the constant pressure chamber, the variable pressure chamber, and the atmosphere. A vacuum valve seat formed on the inner periphery of the valve body, a valve plunger slidably fitted to the valve body and interlocking with the input shaft, and a valve valve located inside the vacuum valve seat, In a booster provided with an atmospheric valve seat formed on a plunger and a valve body which is urged by a spring and seats on both valve seats, an elastic member is attached to a predetermined position in an outer peripheral portion of the valve plunger in an axial direction. , Valve plunger suddenly When the result in advance is to the elastic member is configured to be fitted to an inner periphery of the valve body.

[0005]

According to this configuration, when the brake pedal is rapidly depressed from the inoperative state of the booster, the valve plunger is also rapidly advanced, and in this case, the elastic member provided on the valve plunger is moved forward. Fitted on the inner periphery of the valve body. In addition, the valve element is seated on the vacuum valve seat with the advance of the valve plunger, while being separated from the atmospheric valve seat, and the atmosphere is introduced into the variable pressure chamber. That is, the booster is operated. As described above, when the booster is operated, a reaction disk provided between the output shaft and the valve plunger causes the reaction force of the output acting on the output shaft to act on the valve plunger, thereby causing the valve plunger to move rearward. Acts to push back to the side. However, at this time, since the elastic member is fitted to the inner peripheral portion of the valve body, the sliding resistance of the elastic member temporarily prevents the valve plunger from being pushed back to the rear side with respect to the valve body. You. As a result, the atmosphere valve seat provided on the valve plunger is prevented from being pushed back toward the valve body, so that a large amount of separation between these members can be maintained. Can be introduced. Therefore, operation responsiveness at the time of sudden braking can be improved as compared with the above-described conventional case. Incidentally, when the brake pedal is normally depressed slowly, the elastic member is not fitted to the inner peripheral portion of the valve body. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a substantially cylindrical valve body 2 is slidably fitted in a shell 1 of a brake booster.
A power piston 3 is connected to an outer peripheral portion of the valve body 2.
Is stretched out. The shell 1 is formed by the diaphragm 4.
The interior is partitioned into a constant pressure chamber A on the front side and a variable pressure chamber B on the rear side. In the valve body 2, there is provided a valve mechanism 5 for controlling opening and closing of a fluid circuit between the constant pressure chamber A, the variable pressure chamber B and the atmosphere. The valve mechanism 5 has an annular vacuum valve seat 6 provided on the inner peripheral portion of the valve body 2, a front outer peripheral portion slidably fitted to the inner peripheral portion of the valve body 2, and a rear end. Plunger 8 whose portion is connected to an input shaft 7, and an annular atmospheric valve seat 1 formed at the rear end of the valve plunger 8.
1 and a substantially cylindrical valve body 13 seated on both valve seats 6 and 11 from the rear side by the resilience of a spring 12. A vacuum valve 14 is constituted by the vacuum valve seat 6 and a seat portion of a valve body 13 which comes into contact with / separates from the vacuum valve seat 6. An outer peripheral side of the vacuum valve 14 is an axial constant pressure passage 15 formed in the valve body 2 in the axial direction.
Thus, the pressure chamber A is always in communication with the pressure chamber A. A negative pressure is always introduced into the constant pressure chamber A via a negative pressure introducing pipe 16. An atmosphere valve 17 is constituted by the atmosphere valve seat 11 and a seat portion of the valve body 13 which comes into contact with / separates from the atmosphere valve seat 11, and an intermediate portion between the atmosphere valve 17 and the vacuum valve 14 is a radial hole 2A of the valve body 2. And is always in communication with the variable pressure chamber B via a variable pressure passage 18 composed of Further, the inner peripheral side of the atmospheric valve 17 is an atmospheric passage 21 formed by the internal space of the valve body 2.
Is always in communication with the atmosphere via The atmosphere passage 21
A filter 22 is provided therein. Above valve plunger 8
An annular groove 8a is formed at the axial center of the valve plunger 8 by engaging the key member 23 inserted through the radial hole 2A of the valve body 2 with the annular groove 8a of the valve plunger 8. Is prevented from dropping from the valve body 2. On the inner periphery of the valve body 2,
An annular projection 2B protruding toward the front side is formed, and a concave portion 24a formed at the base of the output shaft 24 is slidably fitted around the outer periphery of the annular projection 2B. Also,
A disk-shaped reaction disk 25 is housed in the concave portion 24a of the output shaft 24, and the reaction disk 25 is interposed between the end surface of the annular projection 2B and the bottom of the concave portion 24a. Further, the valve body 2 and the shell 1
The return spring 26 is elastically mounted on the front wall surface of the shell 1. Therefore, the valve body 2 and the like in a non-operating state are stopped at a non-operating position where the key member 23 is in contact with the rear wall surface of the shell 1. doing. In this non-operating state, the vacuum valve 14 is open while the atmospheric valve 17 is closed. Therefore, the constant pressure chamber A and the variable pressure chamber B communicate with each other, and a negative pressure is introduced into both chambers A and B.
In this non-operating state, the front end face of the valve plunger 8 and the reaction disk 25 facing the end face are opposed to each other.
And a slight gap is maintained between them. The above configuration and the operation based thereon are basically the same as those of the conventionally known brake booster. As shown in FIG. 2 in an enlarged manner, the valve body 2 according to the present embodiment is configured such that the inner peripheral portion on the front side adjacent to the radial hole 2A is slightly larger in diameter than the outer diameter of the valve plunger 8. This is the enlarged diameter portion 2C. The outer peripheral portion of the valve plunger 8 on the front side is slidably fitted to the inner peripheral portion of the valve body 2 on the front side with respect to the enlarged diameter portion 2C. An annular space is maintained between 2C and the outer peripheral portion of the valve plunger 8 on the inner side. An annular groove 8b having a small depth is formed in the outer peripheral portion of the valve plunger 8 on the inner side of the enlarged diameter portion 2C, and an annular elastic member 27 made of rubber is mounted in the annular groove 8b. doing. The outer peripheral portion of the elastic member 27 attached to the annular groove 8b projects slightly outward from the outer peripheral surface of the valve plunger 8 located before and after the annular groove 8b. The annular groove 8b of the valve plunger 8 has its both end surfaces inclined obliquely so that the outer peripheral side is located closer to the front side than the inner peripheral side. A gap having a substantially triangular cross section is maintained between the elastic member 27 and the elastic member 27. (Explanation of operation) In this embodiment configured as described above,
During normal braking in which the brake pedal is gently depressed and the brake booster is operated, as shown in FIG. 2, the elastic member 27 provided on the valve plunger 8
The valve body 2 moves axially relative to the valve body 2 within a range inside the enlarged diameter portion 2C. Therefore, during normal braking in which the brake pedal is gently depressed, the brake pedal operates in the same manner as a conventionally known brake booster. That is, when the brake pedal is gently depressed from the inoperative state of the brake booster shown in FIG. 1, the input shaft 7 and the valve plunger 8 also gently advance. Therefore, the valve body 13 is seated on the vacuum valve seat 6 and the vacuum valve 14 is closed, while the valve body 13 is separated from the atmospheric valve seat 11 and the atmospheric valve 17 is opened. The atmosphere is introduced into the variable pressure chamber B through an open air valve 17 and a variable pressure passage 18. Thereby, the valve body 2 and the power piston 4 are advanced by the differential pressure between the negative pressure in the constant pressure chamber A and the atmospheric pressure in the variable pressure chamber B, and an output of a predetermined servo ratio is obtained from the output shaft 24. Can be. Further, when the brake booster is operated in this manner, the reaction disk 25 is compressed in the axial direction by the output shaft 24 and the annular projection 2B of the valve body 2, so that the shaft of the reaction disk 25 is moved to the rear side. And comes into contact with the front end face of the valve plunger 8 which has been separated. The output reaction force acting on the output shaft 24 from the time of this jumping is the valve plunger 8.
And transmitted to the driver via the input shaft 7. When the brake pedal is rapidly depressed from the non-operation state shown in FIG. 1 in the case of the normal braking described above, the input shaft 7 and the valve plunger 8 linked to the brake pedal are compared with those in the normal braking. The amount of advance relative to the valve body 2 increases. For this purpose, as shown in FIG. 3, an elastic member 27 provided on the valve plunger 8 is fitted to the inner peripheral portion of the valve body 2 on the front side adjacent to the enlarged diameter portion 2C. Thus, the elastic member 2
When the valve member 7 is fitted to the inner peripheral portion of the valve body 2, the sliding resistance of the elastic member 27 temporarily prevents the valve plunger 8 from being pushed back toward the rear side. Therefore, the opening degree of the atmosphere valve 17, that is, the distance between the atmosphere valve seat 11 and the valve body 13 is maintained in a large state,
Atmosphere is quickly introduced into the transformation chamber B through the greatly opened atmosphere valve 17. As a result, the output of the brake booster increases quickly, and the required braking force can be secured. As described above, in this embodiment, the operation responsiveness of the brake booster at the time of sudden braking can be made better than before. When the brake booster is actuated as described above from the time when the brake pedal is suddenly depressed as shown in FIG. 8 is pushed back to the rear side with respect to the valve body 2, so that the elastic member 27 is separated from the inner peripheral portion of the valve body 2 and positioned inside the enlarged diameter portion 2C. In the above-described embodiment, the case where the present invention is applied to a single-type brake booster has been described. The present invention can also be applied to the above-described brake booster. The present invention can also be applied to a clutch booster.

[0007]

As described above, according to the present invention, it is possible to obtain an effect that the operation responsiveness at the time of sudden braking can be improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an operation state of a main part shown in FIG. 1 in a normal state;

FIG. 3 is a sectional view showing an operation state of the main part shown in FIG. 1 at the time of sudden braking.

[Explanation of symbols]

 2 ... Valve body 3 ... Power piston 5 ... Valve mechanism 6 ... Vacuum valve seat 8 ... Valve plunger 11 ... Vacuum valve seat 13 ... Valve 27 ... Elastic member A ... Constant pressure chamber B ... Transformation chamber

Claims (3)

[Claims] 1. A substantially cylindrical valve body slidably provided in a shell, a power piston provided on an outer peripheral portion of the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston. A valve mechanism provided in the valve body for controlling opening and closing of a flow path between the constant-pressure chamber, the variable-pressure chamber, and the atmosphere, wherein the valve mechanism is a vacuum valve seat formed on an inner peripheral portion of the valve body. A valve plunger slidably fitted to the valve body and interlocking with the input shaft; an air valve seat located on the inner side of the vacuum valve seat and formed on the valve plunger; and a spring biased. A booster provided with a valve element seated on both valve seats, wherein an elastic member is attached at a predetermined position in the outer peripheral portion of the valve plunger in the axial direction, and when the valve plunger is rapidly advanced, The elastic member is the valve body Booster, characterized by being configured as fitted to an inner peripheral portion. 2. The valve plunger according to claim 1, wherein an outer peripheral portion on a front side of the valve plunger is slidably fitted to an inner peripheral portion of the valve body and a rear side of the outer peripheral portion of the valve plunger on the front side. The inner peripheral portion is an enlarged portion that is larger than the outer diameter of the valve plunger located on the inner side thereof, and a gap is maintained between the enlarged portion and the outer peripheral portion of the valve plunger, 2. The booster according to claim 1, wherein the elastic member is provided on an outer peripheral portion of a valve plunger located inside the enlarged diameter portion. 3. 3. The booster according to claim 1, wherein the elastic member is made of an annular rubber, and is mounted in an annular groove formed in an outer peripheral portion of the valve plunger. .