JPH08258698A - Servo unit - Google Patents

Abstract

PURPOSE: To reduce the operation start input by forming axially stretching ribs in a plurality of places in circumferential arrangement on the inside surface as the back side of the first valve seat in a valve body, and fitting the cylindrical part of the valve element slidably in the inside circumferences of the ribs. CONSTITUTION: A plurality of ribs 2A extending in the axial direction are formed on the internal circumference of a valve body 6 as the rear side of the first valve seat 6. The ribs 2A are arranged at an equal spacing in the circumferential direction, and their swell-out amounts inward in the radial direction. i.e., the heights, are made the same. The outside surface of the body part 12d of a valve element 12 is slidably fitted in the internal circumferential surfaces of the ribs 2A. A spring 11 to seat the seat parts S1, S2 of the valve element on the valve seats 6, 8 is installed in the area over the end face at the rear of the second radial direction part 12c of valve element 13 and the stepped part of the input shaft 21. This enables enlargement of the pressure receiving area on which the differential pressure generated in front of and behind the valve element 12 acts on the valve element 12.

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 improvement of its valve mechanism.

[0002]

2. Description of the Related Art Conventionally, the following devices have been known as boosters. That is, a cylindrical valve body slidably provided in the shell, an annular first valve seat formed on the inner peripheral portion of the valve body, and a slidably fitted valve body and the input shaft are connected. Valve plunger, an annular second valve seat formed on the valve plunger, a valve body provided in the valve body and seated on the first valve seat and the second valve seat, and the first valve seat. And a vacuum valve configured by a first seat portion of the valve body that contacts and separates from the vacuum valve, and a booster including an atmosphere valve configured by the second valve seat and a second seat portion of the valve body that contacts and separates from the second valve seat. Is known.
By the way, in the conventional general booster described above, when actuated, the atmospheric valve is opened and the vacuum valve is closed. At this time, the negative pressure acts on the outer portion of the first seat portion (vacuum valve) and the atmosphere acts on the inner portion. Therefore, the valve body is biased toward the front side by the pressure difference acting on the valve body. However, the urging force is not large enough to maintain the airtightness of the first seat portion.
The seat (vacuum valve) is kept airtight.

[0003]

However, in the conventional general booster described above, the first seat portion and the second seat portion of the valve body are not used.
The seat portion is formed concentrically, and the diameter of the first seat portion (vacuum valve) is set to be larger than the diameter of the second seat portion (atmosphere valve). Therefore, when the above-mentioned booster is operated, the pressure receiving area where the above-mentioned differential pressure acts on the valve body becomes small, and accordingly, the first area of the valve body is reduced.
The set load of the spring that maintains the airtightness of the seat (vacuum valve) increases. Therefore, conventionally, there has been a drawback that the operation start input of the booster becomes large.

[0004]

[Means for Solving the Problems] In view of such circumstances,
According to the present invention, in the booster described above, a cylindrical portion having rigidity is formed on the front side of the valve body, and a first radial direction portion extending inward in the radial direction is formed on the front side of the cylindrical portion, A second radial direction portion extending inward in the radial direction is formed on the rear side of the cylindrical portion, and the elastic member covering the first radial direction portion constitutes the first seat portion and covers the second radial direction portion. The elastic member forms the second seat portion, and axially extending ribs are formed at a plurality of circumferential positions on the inner peripheral surface of the valve body on the rear side of the first valve seat. The cylindrical portion of the valve body is slidably fitted to the inner peripheral portion of the rib.

[0005]

With this structure, the first seat portion and the second seat portion
Since the seat portion can be separated from the seat portion in the axial direction, it is possible to increase the pressure receiving area when the differential pressure across the valve body acts on the valve body when the booster operates. Therefore, it is possible to reduce the set load of the spring that maintains the airtightness of the first seat portion (vacuum valve) during the operation of the booster, and thus to reduce the operation start input of the booster as compared with the conventional case. You can Further, in the intermediate load state after the booster is operated, the cylindrical portion provided with both seat portions is guided by the ribs and moves relative to the valve body in the axial direction. Therefore, although the first seat portion and the second seat portion are arranged so as to be separated from each other in the axial direction, it is possible to prevent both seat portions that move in the axial direction from inclining, and thus the intermediate load. In this state, airtight leakage of the vacuum valve can be effectively prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, a generally cylindrical valve body 2 is slidably provided in a shell 1 of a brake booster, and an outer peripheral portion of the valve body 2 is provided. The power piston 3 is connected to the
The shell 1 is divided into a constant pressure chamber A and a variable pressure chamber B. A valve mechanism 5 for switching a fluid circuit between the constant pressure chamber A and the variable pressure chamber B is provided in the valve body 2, and the valve mechanism 5 has an annular first valve seat 6 formed on the inner peripheral surface of the valve body 2. 1, an annular second valve seat 8 formed at the rear end of a valve plunger 7 provided slidably on the valve body 2, and a spring 11 from the right side of FIG. The valve body 12 is seated by repulsive force. The first valve seat 6 and the valve body 12 that comes in contact with and separates from the first valve seat 6.
The first seat portion S1 forms a vacuum valve 13, and the space outside the vacuum valve 13 communicates with the constant pressure chamber A through a constant pressure passage 14 formed in the valve body 2. A negative pressure is constantly introduced into the constant pressure chamber A via a negative pressure introducing pipe (not shown). Further, the atmosphere valve 15 is constituted by the second valve seat 8 and the second seat portion S2 of the valve body 12 which comes in contact with and separates from the second valve seat 8, and the space between the atmosphere valve 15 and the vacuum valve 13 is a valve body. It is connected to the variable pressure chamber B through the variable pressure passage 16 formed in 2. The space inside the atmosphere valve 15 is a valve body 2
The atmosphere as a pressure source is communicated with the atmosphere through the atmosphere passage 17 formed in
Is provided. A tip end portion of an input shaft 21 is pivotally connected to an end portion of the valve plunger 7 on the rear side.
The end portion of 1 is connected to a brake pedal (not shown). A spring 23 set to a predetermined set load is elastically mounted between the stepped portion of the input shaft 21 and the retainer 22 having the base portion 12a of the valve body 12 fixed to the valve body 2. The input shaft 21 is biased to the rear side by the so as to be stopped at the inoperative position in the drawing. On the other hand, a reaction disc 24 is arranged on the front side of the valve plunger 7, and the reaction disc 24 is fitted to the rear end of the push rod 25. The front end of the push rod 25 is slidably projected to the outside from the front wall surface of the shell 1 and is interlocked with the piston of a master cylinder (not shown). The valve body 2 is biased to the rear side by a return spring 26, and is normally located at a non-actuated position in the drawing. In the non-operating state of the brake booster shown in FIG. 1, the vacuum valve 13 is open and the atmosphere valve 15 is closed. Further, in this state, the front side of the valve body 12 becomes negative pressure, and the valve body 1
The rear side in 2 is at atmospheric pressure. Therefore, the valve body 12 is biased toward the front side by the pressure difference between the front and rear sides of the valve body 12, but the pressure difference causes the spring 23 to be stronger than the biasing force that biases the valve body 12 toward the front side. The valve body 12 and the input shaft 21 are stopped in the non-actuated position in the figure because the repulsive force is larger. The configuration described above and the operation based on it are the same as those conventionally known.
Therefore, in the present embodiment, by improving the valve mechanism 5, the operation start input can be reduced and the airtight leakage of the vacuum valve 13 in the intermediate load state after the operation start can be prevented. That is, the valve body 12 of the present embodiment is constituted by a rigid cylindrical portion 12A provided on the front side thereof and a rubber-made substantially cylindrical elastically deforming portion 12B connected to the rear side of the cylindrical portion 12A. ing. The rear end of the elastically deformable portion 12B is the thickly formed base portion 12a, and as described above, the base portion 12a is fixed to the inner peripheral surface of the valve body 2 by the retainer 22. On the other hand, the cylindrical portion 12A has a first radial portion 12 that extends inward in the radial direction at the front end thereof.
In addition to b, the rear side end portion is also provided with a second radial portion 12c that also extends radially inward. The front end of the elastically deformable portion 12B is connected to the rear end surface of the second radial portion 12c. Both end surfaces and the inner peripheral portion of the first radial direction portion 12b are covered with an annular rubber, and the second radial direction portion 1 is also provided.
The front end surface of 2c is also covered with an annular rubber. The first sheet portion S1 is formed by the rubber covering the front side end surface of the first radial direction portion 12b, and the second sheet portion S2 is formed by the rubber covering the front side end surface of the second radial direction portion 12c. I am configuring. In this embodiment, the diameter of the first seat portion S1 and the diameter of the second seat portion S2 are set to be substantially the same. As described above, in the present embodiment, unlike the configuration of the conventional general valve mechanism 5, the seat portions S1 and S2 have substantially the same diameter and are arranged so as to be displaced in the axial direction. The first radial portion 12b provided with the first seat portion S1 is manufactured integrally with the cylindrical main body portion 12d, but the second radial portion 1
2c is manufactured separately from the main body portion 12d and then integrally connected. That is, in this embodiment, the first radial direction portion 12b and the main body portion 12d are integrally manufactured by drawing, and at the same time, the rubber that becomes the first seat portion S1 is joined to the first radial direction portion 12b. The front part of the body 12 is manufactured. On the other hand, the rubber that becomes the second seat portion S2 is joined to the front end surface of the second radial portion 12c, and the front end portion of the elastically deformable portion 12B is connected to the rear end surface of the second radial portion 12c. By joining, the rear side portion of the valve body 12 is manufactured. After the front side portion and the rear side portion that constitute the valve body 12 are manufactured in this manner, the main body portion 12
The second radial portion 12c is press-fitted from the rear side into the inner peripheral portion on the rear side of d. Then, the required portion of the outer peripheral portion on the rear side of the second radial direction portion 12d is crimped to integrally connect the main body portion 12d and the second radial direction portion 12c, whereby the manufacture of the valve body 13 is completed. Further, in this embodiment, a plurality of ribs 2A extending in the axial direction are formed on the inner peripheral portion of the valve body 6 on the rear side of the first valve seat 6. The ribs 2A are provided at positions at equal intervals in the circumferential direction, and have the same bulging amount inward in the radial direction, that is, the same height. The outer peripheral surface of the main body portion 12d of the valve body 12 is slidably fitted to the inner peripheral surfaces of the plurality of ribs 2A. Further, in the present embodiment, the spring 11 for seating the seat portions S1, S2 of the valve body 12 on the valve seats 6, 8 includes the rear end face of the second radial portion 12c of the valve body 13 and the input shaft 21. It is provided over the stepped part of. According to the present embodiment configured as described above, the diameters of both seat portions S1 and S2 are substantially the same, and they are separated from each other in the axial direction.
Therefore, in the operating state of the brake booster in which the atmospheric valve 15 is opened and the vacuum valve 13 is closed, the valve body 1
It is possible to increase the pressure receiving area where the differential pressure generated before and after 2 acts on the valve body 12. That is, the biasing force due to the differential pressure for seating the first seat portion S1 on the first valve seat 6 becomes large. Thereby, the set load of the spring 11 for keeping the airtightness of the first seat portion S1 (vacuum valve 13) can be reduced, and therefore the input of the input shaft 21 at the start of the operation of the brake booster can be reduced. You can In contrast to the present embodiment as described above, the conventional valve body 12 has the first seat portion S1.
Since the second sheet portion S2 and the second sheet portion S2 are formed concentrically,
The diameter of the first seat portion S1 is larger than the diameter of the second seat portion S2. In such a conventional valve body 12, the pressure receiving area where the differential pressure generated before and after the valve body 12 acts on the valve body 12 during operation of the brake booster becomes small, and accordingly, the spring 11 is set. It has been pointed out that the load increases, and the operation start input of the brake booster increases. Also,
In the present embodiment, in the intermediate load state after the operation of the brake booster is started, the cylindrical portion 12A provided with the seat portions S1 and S2 is guided by the plurality of ribs 2A in the axial direction with respect to the valve body 6. It will move relative. Therefore, the axial center of the valve body 12 and the axial center of the valve body 2 can always be made to coincide with each other, and therefore the first seat portion S1 seated on the first valve seat 6 can be favorably prevented from inclining. You can Therefore, it is possible to favorably prevent airtight leakage of the vacuum valve 13 in the intermediate load state. (Second Embodiment) Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the retainer 122
The inner peripheral edge of the front side of the cylindrical body 22a is extended in the axial direction to form a cylindrical portion 22a, and a step end surface 122a 'formed on the rear side of the cylindrical portion 122a and the valve body 1 facing it.
A cylindrical spring 111 is elastically mounted over the rear end surface of the second radial portion 112c of the reference numeral 12. The other structure is the same as that of the first embodiment, and the corresponding members are allotted with the member numbers added with 100.
The second embodiment having such a configuration can also obtain the same effects as the first embodiment. Although each of the above embodiments has been described with respect to a case where the present invention is applied to a single type brake booster, the present invention can also be applied to a tandem booster or a triple type booster.

[0007]

As described above, according to the present invention, it is possible to obtain an effect that the operation start input of the booster can be reduced as compared with the conventional case. Further, it is possible to effectively prevent the airtight leak of the vacuum valve in the intermediate load state.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

2 ... Valve body 3 ... Power piston 5 ... Valve mechanism 6 ... First valve seat 7 ... Valve plunger 8 ... Second valve seat 11 ... Spring 12 ... Valve element 13 ... Vacuum valve 15 ... Atmosphere valve 21 ... Input shaft S1 ... First Seat part S2 ... Second seat part A ... Constant pressure chamber B ... Transformer chamber

Claims (2)

[Claims] 1. A tubular valve body slidably provided in a shell, an annular first valve seat formed on an inner peripheral portion of the valve body, and a slidably fitted input to the valve body and input. A valve plunger to which a shaft is connected; an annular second valve seat formed on the valve plunger; a valve body provided in the valve body and seated on the first valve seat and the second valve seat; A vacuum valve constituted by one valve seat and a first seat portion of the valve body coming into contact with and separated from the valve seat, and an atmospheric valve constituted by the second valve seat and a second seat portion of the valve body coming into contact with and separated from the second seat In the booster, a rigid cylindrical portion is formed on the front side of the valve body, a first radial direction portion extending radially inward is formed on the front side of the cylindrical portion, and a rear side of the cylindrical portion is formed. Second radial direction extending inward in the radial direction Parts forming a first
An elastic member that covers the radial portion configures the first seat portion, and an elastic member that covers the second radial portion configures the second seat portion. Further, the first seat portion of the valve body is formed. Ribs extending in the axial direction are formed at a plurality of circumferential positions on the inner peripheral surface on the rear side, and the cylindrical portion of the valve element is slidably fitted to the inner peripheral portions of the plurality of ribs. Characteristic booster. 2. A spring for seating both seat portions of the valve body on the respective valve seats extends over the second radial portion and the input shaft, or a retainer which fixes the base portion of the valve body to the valve body, and the first and second retainers. The booster according to claim 1, wherein the booster is elastically mounted over two radial portions.