JP2516926Y2 - Brake booster - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a brake booster, and more specifically, a key member that is interlocked with a valve plunger when the brake booster is not activated is applied to an inner wall surface of a shell. To control the valve plunger and the free retraction of the input shaft linked to it,
The present invention relates to a brake booster that reduces the loss stroke of the input shaft during the next brake operation.

"Prior Art" Conventionally, as a brake booster, a valve body slidably arranged in a shell, a valve mechanism housed in the valve body, and a valve mechanism that is interlocked with a valve plunger that constitutes the valve mechanism. An input shaft for switching and controlling the flow path of the valve and a key member that interlocks with the valve plunger, and when the brake booster is not operated, the key member is attached to the inner wall surface of the shell, normally when the shell is attached to the vehicle body. It is known that the valve plunger is brought into contact with the inner surface of the mounting portion to restrict the free retreat of the valve plunger so as to reduce the loss stroke of the input shaft during the next braking operation.

By the way, a brake booster generally includes a tubular protrusion that is formed by opening the center of the shell on the rear side in a tubular shape, and sliding the rear tubular portion of the valve body into the tubular protrusion. It is freely pierced and protruded to the outside, and a sealing member is provided in the cylindrical protruding portion to maintain airtightness between the sealing member and the cylindrical portion of the valve body.

Further, conventionally, a flange portion extending inward in the radial direction is formed on the cylindrical protruding portion of the shell, and the inner peripheral portion is cut to form the opening, and the key member is brought into contact with the inner wall surface of the flange portion. There is also known a brake booster in which the valve plunger is restrained from freely retracting and the seal member is housed and held in a housing provided outside the shell (Japanese Patent Laid-Open No. 63-63). 126163).

[Problems to be Solved by the Invention] However, in the former conventional general brake booster, the seal member is positioned on the outer periphery of the cylindrical portion of the valve body, and the cylindrical member holding the seal member on the outer periphery of the seal member. The protruding portion is located, and the contact surface of the key member is located on the outer periphery of the cylindrical protruding portion.

As a result, a space for providing the seal member is required between the abutment surface of the key member and the outer peripheral surface of the valve body, and the length of the key member is accordingly increased.
Therefore, it is necessary to increase the wall thickness in order to secure its strength, which is a factor that causes an increase in weight of the brake booster and an increase in axial length.

On the other hand, in the latter brake booster, since the inner peripheral edge of the flange portion can be brought close to the outer peripheral surface of the tubular portion of the valve body, the length of the key member can be made shorter than in the conventional case. As a result, the weight and thickness of the key member can be reduced, and the brake booster can be reduced in weight and axial length.

However, the abutting surface of the key member is a flange portion formed in the tubular protrusion and extending inward in the radial direction, and this portion is subjected to a pressure difference between the inside and outside of the shell, and is separated from the attachment portion of the shell to the vehicle body. Therefore, the shell is slightly displaced in the axial direction between the introduction state in which the pressure fluid is introduced and the non-introduction state in which the pressure fluid is not introduced.

When the contact surface of the key member is displaced in the axial direction between the introduction state and the non-introduction state of the pressure fluid, the stop position of the valve body or the push rod stopped by this is displaced in the axial direction. Even if the master cylinder was installed in the brake booster in this condition, the installation condition fluctuated in the installed condition.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention shortens the length of the key member as compared with the former general brake booster, thereby reducing the weight and thickness of the key member. The brake booster can be made lighter and its axial length can be shortened, and at the same time, like the latter brake booster, the introduction and non-introduction of pressure fluid into the shell The contact surface of the key member is prevented from being displaced in the axial direction depending on the state.

That is, according to the present invention, a shell, a cylindrical protruding portion in which a rear side central portion of the shell is cylindrically protruded and opened, and a rear cylindrical portion is slidably disposed in the shell. The valve body is slidably pierced through the cylindrical protruding portion and protruded to the outside, the valve mechanism housed in the valve body, and the flow path of the valve mechanism is switched in conjunction with the valve plunger forming the valve mechanism. A brake booster equipped with an input shaft to be controlled and a key member that interlocks with the valve plunger and restricts free retraction of the valve plunger when not operating to reduce a loss stroke of the input shaft. A stopper plate is sandwiched and fixed to the inner wall surface of the mounting portion to the vehicle body by the inner wall surface and the head of the mounting bolt, and between the inner wall surface of the mounting portion of the shell and the facing surface of the stopper plate. A minute gap is provided, the stopper plate is projected radially inward from the inner diameter of the cylindrical projection, and the key member is brought into contact with the projection to restrict the free retraction of the valve plunger. It was done.

[Operation] According to the above configuration, a part of the stopper plate is projected further inward in the radial direction than the inner diameter of the cylindrical projecting portion, and the key member is brought into contact with the projecting portion. The length of the key member can be made shorter than that of the former brake booster, thereby reducing the weight and thickness of the key member to reduce the weight of the brake booster and shorten the axial length. It becomes possible.

The stopper plate is attached to a portion that does not shift axially between the introduction state and the non-introduction state of the pressure fluid into the shell, that is, the inner wall surface of the attachment portion of the shell to the vehicle body. The pressure difference between the inside and outside of the shell does not act on this stopper plate. Therefore, the contact surface of the key member of the stopper plate does not shift in the axial direction between the introduction state and the non-introduction state of the pressure fluid into the shell, so that the master cylinder is installed in the brake booster in the non-introduction state. Even when assembled, the assembled state does not change depending on the installed state.

[Embodiment] The present invention will be described below with reference to an illustrated embodiment. In the drawings, a power piston 2 is slidably provided in a shell 1 of a brake booster, and the power piston 2
A diaphragm 3 is stretched on the back of the shell, and the power piston 2 and the diaphragm 3 divide the inside of the shell 1 into a constant pressure chamber 4 at the front and a variable pressure chamber 5 at the rear. A valve body 6 is integrally provided on the shaft portion of the power piston 2, and a valve mechanism 7 for switching the flow path in the valve body 6 is provided.
Is stored.

The valve mechanism 7 is the first valve seat 1 formed on the valve body 6.
0, second valve seat 12 formed on valve plunger 11 and double valve seat 1
The valves 0 and 12 are provided with a valve body 14 which is seated from the rear side of the power piston 2, that is, from the right side of the drawing by the elastic force of the spring 13. The outer side of the seat portion of the first valve seat 10 and the valve body 14 is communicated with the constant pressure chamber 4 through a passage 15 formed in the valve body 6, and the inside of the constant pressure chamber 4 is provided in the shell 1. A negative pressure source such as an intake manifold of the engine is connected via a pressure introducing pipe 16.

On the other hand, the intermediate portions of the respective seal portions of the first valve seat 10 and the valve body 14 and the second valve seat 12 and the valve body 14 are communicated with the variable pressure chamber 5 through the passage 17 formed in the valve body 6, and The inside of the seat portion of the second valve seat 12 and the valve element 14 is communicated with the atmosphere via a filter 18.

Further, the valve plunger 11 constituting the valve mechanism 7 is connected to an input shaft 25 which is interlocked with a brake pedal (not shown),
The tip surface of the valve plunger 11 is a reaction disc housed in a recess formed in the base of the push rod 26.
Facing 27. The push rod 26 penetrates the seal member 28 so as to protrude to the outside of the shell 1 and is interlocked with the piston of a master cylinder (not shown).

However, a stepped cylindrical projecting portion 1a extending axially toward the rear side is projectingly formed in the central portion on the rear side of the shell 1, and the cylindrical projecting portion 1a is sequentially arranged at two axial positions. Steps 1b and 1c are formed by reducing the diameter.

On the other hand, a stopper plate 33 is provided on the inner wall surface of the mounting portion 1d of the shell 1 on the vehicle body 31, that is, on the inner wall surface of the mounting portion 1d of the bolt 32 mounted on the shell 1 for mounting the shell 1 on the vehicle body 31. . This stopper plate 33 is
The ring-shaped portion 33a extending in the radial direction and the ring-shaped portion 3
A cylindrical portion 33b that extends axially rearward from 3a, and a ring-shaped protrusion 33c that extends radially inward from the end of the cylindrical portion 33b are provided.

Then, the cylindrical portion 33b of the stopper plate 33 is loosely fitted into the cylindrical protruding portion 1a on the larger diameter side of the step portion 1b with a slight gap, and the inner wall surface of the step portion 1b of the shell 1 is formed. By forming a minute gap between the stopper plate 33 and the surface facing the inner wall surface, and by sandwiching the ring-shaped portion 33a of the stopper plate 33 between the head of the bolt 32 and the shell 1 in this state, The stopper plate 33 is attached to the shell 1.

The cylindrical portion 6a formed on the rear side of the valve body 6 is
The inside of the ring-shaped protruding portion 33c of the stopper plate 33 and the inside of the cylindrical protruding portion 1a of the shell 1 are loosely fitted to be slidably projected to the outside, and normally, the valve body 6 is powered by the return spring 35. The piston 2 and the like are held in a non-operating position in the drawing. In this non-operating state, the key member 36 for preventing the valve plunger 11 from coming out of the valve body 6 is brought into contact with the protruding portion 33c of the stopper plate 33 so that the valve plunger 11 can freely move to the right of the valve body 6. The restriction is made so that the switching operation of the fluid circuit by the valve mechanism 7 can be obtained immediately when the input shaft 25 and the valve plunger 11 are subsequently operated.

Further, a bearing 37 that slidably contacts the cylindrical portion 6a of the valve body 6 and supports the cylindrical portion 1a between the protruding portion 33c of the stopper plate 33 and the step portion 1c of the cylindrical protruding portion 1a.
And a sealing member 38 that keeps airtightness inside the shell 1 by slidingly contacting the tubular portion 6a are sequentially arranged from the front side to the rear side.

In the above structure, when the brake pedal (not shown) is stepped on and the input shaft 25 and the valve plunger 11 are moved leftward, the valve body 14 is seated on the first valve seat 10 of the valve body 6 and the variable pressure chamber 5 and the constant pressure chamber. The second valve seat 12 of the valve plunger 11 is separated from the valve body 14 while the communication between the four is cut off, and the atmosphere and the variable pressure chamber 5 are communicated with each other. As a result, the atmosphere is supplied into the variable pressure chamber 5, and the power piston 2 is advanced against the repulsive force of the return spring 35 due to the pressure difference before and after the power piston 2 as in the conventionally known brake booster. , Braking is performed.

When the depression force of the brake pedal is released from the brake operating state, the second valve seat 12 of the valve plunger 11 is seated on the valve body 14 to block the communication between the variable pressure chamber 5 and the atmosphere, and
14 separates from the first valve seat 10 to connect the variable pressure chamber 5 to the constant pressure chamber 4, so that the power piston 2 operates the return spring 35.
Will return to the original non-actuated position.

When the power piston 2 retracts, the key member
When 36 abuts on the protruding portion 33c, the backward movement of the valve plunger 11 which is interlocked with this is stopped, but the backward movement of the power piston 2 and the valve body 6 continues, and the backward movement of the valve body 6 causes the first valve seat 10 of the valve body 6 to move. When the valve body 14 approaches the valve body 14 and the gap between them becomes almost zero, the valve body 6 comes into contact with the key member 36 and stops, or the valve body 6 stops.
When the valve body 6 can be further retracted without coming into contact with the key member 36, the second valve seat 12 is opened, the atmosphere is introduced into the variable pressure chamber 5, and the power piston 2 is slightly advanced to move the first valve seat 6 forward. And the power piston 2 stops with both the second valve seats closed. Therefore, when the input shaft 25 is moved forward again, the flow path of the valve mechanism 7 is immediately switched.

At this time, the protruding portion 33c of the stopper plate 33 is located radially inward of the inner diameter of the cylindrical protruding portion 1a of the shell 1.
It projects beyond the outer peripheral portions of the bearing 37 and the seal member 38 to the inside thereof, and is close to the outer peripheral surface of the tubular portion 6a of the valve body 6. Therefore, as compared with the conventional device in which the contact surface of the key member is formed further outside the outer peripheral portions of the bearing 37 and the seal member 38, the protrusion 33 is formed.
The length of the key member 36 abutting on c can be shortened,
As a result, the weight and thickness of the key member can be reduced, and the brake booster can be reduced in weight and axial length.

Further, the stopper plate 33 with which the key member 36 abuts
Is attached to the attachment portion 1d of the shell 1 to the vehicle body 31, and the protruding portion 33c of the stopper plate 33 may be affected by the pressure even if negative pressure or atmospheric pressure is introduced into the variable pressure chamber 5. Since it does not exist, the projecting portion 33c of the stopper plate 33 is not displaced in the axial direction depending on whether the negative pressure is introduced into the shell 1 or not.

Therefore, even when the master cylinder (not shown) is assembled to the brake booster, even if the push rod 26 and the piston of the master cylinder (not shown) are adjusted to the proper state and assembled without negative pressure being introduced into the shell 1. After that, when a negative pressure is introduced into the shell 1, the assembled state does not change.

[Advantage of Invention] As described above, according to the present invention, since the length of the key member can be shortened, the weight and the wall thickness of the key member can be reduced to reduce the weight and the axial direction of the brake booster. The length can be shortened, and the contact surface of the key member of the stopper plate does not shift in the axial direction between the introduction state and the non-introduction state of the pressure fluid in the shell. Even if the master cylinder is assembled to the brake booster in the state, the assembled state does not change in the introduced state, and the effect that the assembly can be facilitated is obtained.

[Brief description of drawings]

 FIG. 1 is a sectional view showing an embodiment of the present invention. 1 ... Shell, 1a ... Cylindrical protrusion 1d ... Attachment part, 6 ... Valve body 6a ... Cylindrical part, 7 ... Valve mechanism 11 ... Valve plunger, 25 ... Input shaft 26 ... Push rod, 31 ... Vehicle body 32 ... Bolt, 33 ... Stopper plate 33a ... Projection, 36 ... Key member

Claims (1)

(57) [Scope of utility model registration request] 1. A shell, a tubular projection in which a central portion of the rear side of the shell is projected in a tubular shape and opened, and a tubular portion on the rear side which is slidably disposed in the shell. The valve body is slidably pierced through the cylindrical protruding portion and protruded to the outside, the valve mechanism housed in the valve body, and the flow path of the valve mechanism is switched in conjunction with the valve plunger forming the valve mechanism. A brake booster equipped with an input shaft to be controlled and a key member that interlocks with the valve plunger and restricts free retraction of the valve plunger when not operating to reduce a loss stroke of the input shaft. A stopper plate is sandwiched and fixed to the inner wall surface of the mounting portion to the vehicle body by the inner wall surface and the head of the mounting bolt, and a minute gap is provided between the inner wall surface of the shell and the facing surface of the stopper plate, A brake characterized in that the stopper plate is projected radially inward from the inner diameter of the tubular projection, and the key member is brought into contact with the projection to restrict the free retraction of the valve plunger. Booster.