JPS6232935Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention provides a brake booster, in particular a housing, a housing that can move forward and backward within the housing, and a rear wall of the housing. a power piston having a cylindrical part that slidably penetrates through the housing and protrudes outside the housing; and a diaphragm that has an inner peripheral edge fixed to the power piston within the housing and an outer peripheral edge fixed to the housing. a front chamber defined within the housing by the diaphragm, the diaphragm and the power piston, and constantly communicating with a negative pressure source; and a front chamber defined within the housing by the diaphragm and the power piston. a chamber, and the power piston is configured to cause atmospheric air to flow into the rear chamber in response to depression of the brake pedal to advance the power piston, and to cause atmospheric air in the rear chamber to flow out to the rear and front chambers in response to release of the brake pedal. and a master cylinder pressing rod that slidably penetrates the front wall of the housing and projects outside the housing, and the control valve is slidable into the power piston. The brake pedal includes a valve body disposed in the cylindrical portion and connected to the brake pedal via a rod protruding rearward from the rear end opening of the cylindrical part, and the amount of sliding of the valve body with respect to the power piston is determined by the amount of sliding of the valve body with respect to the power piston. The radial passage of the locking piece is limited by a locking piece inserted into a provided radial passage hole and having its inner end engaged with a circumferential groove on the outer periphery of the valve body. The present invention relates to an improvement in a brake booster in which the brake booster is prevented from coming off from the hole by engagement between the inner circumferential edge of the diaphragm and the outer end of the locking piece.

(Prior Art) A conventional brake booster of this type is shown in FIG. In Figure 4, 31
32 is a housing, 32 is a power piston, 33 is a diaphragm, 34 is a front chamber, 35 is a rear chamber, 36 is a control valve, 37 is a valve body, 38 is a locking member, 39 is a master cylinder pressing rod, 40 is a valve seat , 41 is a first spring, and 42 is a second spring.

Normally, in this type of brake booster, when the brake pedal is depressed, air flows into the rear chamber 35 to advance the power piston 32, and when the brake pedal is released, the air inside the rear chamber 35 is forced into the front chamber. As shown in FIG. 4, a control valve 36 for retracting the power piston 32 by allowing the flow to flow into the power piston 34 is slidably disposed within the cylindrical portion of the power piston 32 and protrudes rearward from the rear end opening of the cylindrical portion. A valve body 37 is connected to the brake pedal through a rod.
and a valve seat 40 which is disposed within the cylindrical portion and on which the rear end of the valve body 37 can be seated. The control valve 36 has a first spring 41 that urges the valve seat 40 forward so that the valve body 37 seats on the valve seat 40 and blocks communication between the rear chamber 35 and the atmosphere when the brake booster is not activated. The rod is biased rearward by a second spring 42 whose spring constant is set larger than that of the first spring 41. Therefore, the valve body 37 is urged rearward by the second spring 42 via the rod, separating the valve body 37 from the valve seat 40, allowing atmospheric air to flow into the rear chamber 35, and causing the power piston 32 to move forward. The amount of depression of the brake pedal is determined by the installation height of the brake pedal, to which the rear end of the rod is connected, relative to the passenger compartment floor, resulting in instability and the control valve easily falling out of the power piston before it is installed in the vehicle. Therefore, conventionally, a locking piece is inserted into a radial passage hole provided in the power piston, and the inner end of the locking piece is engaged with a circumferential groove on the outer periphery of the valve body, thereby preventing the valve body from touching the power piston. The retracted position was restricted and the amount of sliding of the valve body relative to the power piston was restricted.

However, in the brake booster shown in FIG.
A radial through hole 3 provided in the power piston 32 for inserting a locking member 38 that engages with the locking member 38 to limit the amount of sliding of the valve body 37 relative to the power piston 32.
2a is a diaphragm 33 in the sliding direction of the valve body.
The inner peripheral edge 3 of the diaphragm 33 at the outer end of the locking member 38 is placed at the same position as the inner peripheral edge 33a of the diaphragm 33 to prevent the locking member 38 from coming off from the radial through hole 32a.
This is done by engaging 3a.

(Problems to be Solved by the Invention) In the above-described conventional brake booster shown in FIG. Since this is done by engaging the valve body, it has the advantage of not requiring a special member to prevent it from coming off, but the radial hole is located at the same position as the inner peripheral edge of the diaphragm in the sliding direction of the valve body. Therefore, the circumferential groove of the valve body is also located at the same position as the inner peripheral edge of the diaphragm in the sliding direction of the valve body.
The distance L1 between the front end of the center of the power piston and the mounting surface of the housing is large, and as a result, the amount of protrusion L2 of the housing from the mounting surface of the housing has to be increased. As a result, there was a practical problem in that the mounting space was limited when mounting the device on a vehicle.

Therefore, the technical problem of the present invention is to make it possible to shorten the distance L1 and, accordingly, shorten the distance L2 as compared to the conventional device.

[Structure of the idea]

(Technical means for solving the problem) The technical means taken to solve the above-mentioned technical problem is to engage the inner end with the circumferential groove on the outer periphery of the valve body, so that the valve body is connected to the power piston. A radial hole is provided in the power piston in order to insert a locking piece that regulates the amount of sliding of the valve body, and the hole is provided on the rod side of the inner peripheral edge of the diaphragm in the sliding direction of the valve body, and the locking piece is removed. The end is L-shaped and has a bent claw portion that extends forward to the inner diameter side of the inner peripheral edge of the diaphragm through a notch formed on the outer periphery of the power piston. The device is prevented from slipping out of the hole by engaging the tip of the bent claw portion with the inner circumferential edge of the diaphragm.

(Function) As a result, the valve body can be positioned behind the inner circumferential edge of the diaphragm in the sliding direction, and the distance between the front end of the center of the power piston and the mounting surface of the housing can be shortened compared to before. The amount of protrusion of the housing from the mounting surface of the housing can be reduced.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings. In FIG. 1, the inside of a housing 1 is divided into a front chamber 4 and a rear chamber 5 by a power piston 2 and a diaphragm 3. The power piston 2 has a cylindrical portion 2a that slidably penetrates the rear wall 1a of the housing 1. Diaphragm 3 is
Its outer periphery is airtightly attached to the peripheral wall 1b of the housing 1, and its inner periphery is fitted into the circumferential groove 2r of the power piston 2 and airtightly attached, and between the front chamber 4 and the rear chamber 5. It is kept airtight.

The rod 7 connected and engaged with the brake pedal (not shown) is inserted from the rear end opening of the cylindrical portion 2a, and its front end engages with the valve body 6a guided along the inner circumferential wall 2i of the power piston 2. There is. When the brake pedal is depressed, the rod 7 moves forward, and the rubber valve seat 6b first comes into contact with the valve protrusion 2b provided on the power piston 2, so that the passage 2c on the power piston 2 is constantly in communication with the rear chamber 5. Then, the valve body 6a connects the passage 2d to the atmospheric chamber 2e from the valve seat 6b. The valve body 6a, the valve seat 6b, and the valve protrusion 2b form a control valve 6, and the passage 2c is always in communication with a front chamber 4, and the front chamber 4 is always connected to an engine intake manifold (not shown). It's communicating. Further, the atmospheric chamber 2e is always in communication with the atmosphere, and as is well known in the art, the valve seat 6b is urged forward by the first spring 12 and the valve body 6a is pushed forward by the rod. By being biased rearward by the second spring 13 via the valve body 6a, the valve body 6a is seated on the valve seat 6b and communication therebetween is cut off when the brake booster is not in operation. The radial through hole 2g is provided adjacent to the passage 2f, and an L-shaped locking piece 8 is fitted into the radial through hole 2g. It extends forward through the notch 2s of the groove 2r, and is prevented from coming out of the hole 2g by the inner periphery 3a of the diaphragm 3. The inner end of the locking piece 8 engages with the circumferential groove 6c of the valve body 6a. The passage 2f is bored in the inner circumferential wall 2i of the power piston 2 and communicates with the rear chamber 5. In addition, the inner circumferential wall 2i of the piston 2 is textured,
A valve body 6a slidably fitted therein is inserted into the inner circumferential wall 2.
The portion that does not come into contact with i becomes a gap or passage 2j and communicates with passage 2f. Therefore, when the brake is operated, the atmosphere comes to communicate with the rear chamber 5 through the passage 2e, passage 2d, and passage 2f.

The spring 9 is connected to a retainer 10 fixed to the front end of the power piston 2 and a front wall 1c of the housing 1.
It is stretched between. Further, a master cylinder (not shown) pressing rod 11 that slidably passes through the front wall 1c of the housing 1 is connected and engaged with the power piston 2 at its rear end. The reaction rubber member 12 applies a reaction force to the brake pedal in accordance with the forward force of the power piston 2 during brake operation.

In Figure 2, the radial through hole 2g and the passage 2
It can be seen how f is adjacent to each other.

In FIG. 3, among the convex portions of the inner circumferential wall 2i of the piston 2, those facing the passage 2f serve to guide the valve body 6a in the axial direction, and the concave portions of the inner circumferential wall 2i and the valve body 6a Passage 2 formed by
j communicates negative pressure or the atmosphere to the rear chamber 5 through a passage 2f.

The operation will be explained in the above configuration.

If the brake pedal is released, the first
As shown in the figure, a control valve 6 communicates the front chamber 4 and the rear chamber 5 to maintain the same negative pressure in both chambers. However,
The power piston 2 and the master cylinder rod 11 are held by a spring 9 in the inactive position shown. When the brake pedal is depressed, the rod 7 moves forward and releases the valve body 6b of the control valve 6.
contacts the valve protrusion 2b to cut off communication between the front chamber 4 and the rear chamber 5, and the valve body 6a contacts the first and second springs 1.
By resisting the biasing forces 2 and 13 and separating from the valve seat 6b, the rear chamber 5 is switched from negative pressure to the atmosphere. Then, the air pressure in the rear chamber 5 becomes higher than the air pressure in the front chamber 4, and a forward force is generated in the power piston 2 according to the difference in air pressure between the two chambers.The power piston 2 moves forward due to the forward force, and the rod 11 Activate the master cylinder via. Then, when the brake pedal is released again, the power piston 2 retreats due to the restoring force of the spring 9, and the valve body 6a is seated on the valve seat 6b due to the urging force of the first and second springs 12, 13, and the rear chamber 5 By cutting off communication with the atmosphere,
Next, the valve seat 6b separates from the valve protrusion 2b and the front chamber 4
and the rear chamber 5 to make both chambers have the same negative pressure. At this time, the locking piece 8 prevents the valve body 6a from retreating. In other words, the locking piece 8 regulates the position of the valve body 6a, so that the valve seat 6b comes into contact with the valve protrusion 2b, further separating the valve body 6a from the valve seat 6b and moving the valve body 6a into the rear chamber 5. The amount of depression of the brake pedal required to move the power piston 2 forward is kept constant. In addition, in this embodiment, the inner end is connected to the circumferential groove 6c on the outer periphery of the valve body 6a.
The valve body 6a for the power piston 2 is engaged with the valve body 6a.
A radial passage hole 2g provided in the power piston for inserting a locking piece 8 for regulating the amount of sliding is provided closer to the rod 7 than the inner peripheral edge 3a of the diaphragm 3 in the sliding direction of the valve body 6a. The locking piece 8 has a bent claw portion 8a whose outer end extends forward and extends through a notch 2s formed on the outer periphery of the power piston 2 to the inner diameter side of the inner peripheral edge 3a of the diaphragm 3. The locking piece 8 is L-shaped, and the locking piece 8 is prevented from coming off from the radial passage hole 2g by the engagement between the tip of the bent claw part 8a and the inner peripheral edge 3a of the diaphragm 3. There is no need for a special member to prevent the valve from coming off, and the valve body 6a can be positioned rearward from the inner circumferential edge 3a of the diaphragm 3 in its sliding direction. The distance between the housing 1 and the mounting surface can be shortened compared to the conventional case, and the amount of protrusion of the housing 1 from the mounting surface of the housing 1 can be shortened. In this embodiment, the radial through hole is located in front of the mounting surface of the housing, but if the radial through hole is located behind the mounting surface of the housing, it will be further away from the mounting surface of the housing. It is also possible to shorten the amount of protrusion of the housing.

[Effect of idea]

According to the present invention, the valve body can be arbitrarily positioned on the rod side from the inner peripheral edge of the diaphragm in the sliding direction of the power piston, and the distance between the front end of the center of the power piston and the mounting surface of the housing is This allows the housing to protrude from the mounting surface by reducing the length of the housing.
It is possible to suppress restrictions in terms of installation space when mounting on a vehicle.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the brake booster of the present invention.
2 is a partial view of the power piston as viewed from FIG. 1A, FIG. 3 is a sectional view taken along line BB of the brake booster shown in FIG. 1, and FIG. 4 is a sectional view of a conventional brake booster. 1...Housing, 2...Power piston, 2
a... Cylindrical part, 2f... Passage, 2g... Radial through hole, 2i... Power piston inner peripheral wall, 2j...
Passage, 2s...Notch, 3...Diaphragm, 3
a... Inner peripheral edge, 4... Front chamber, 5... Back chamber, 6...
...control valve, 6a...valve body, 6b...valve seat, 6c...
... Circumferential groove, 7... Rod, 8... Locking piece, 8a
...Bending claw portion, 11...Master cylinder pressing rod.

Claims (1)

[Scope of utility model registration request] a power piston that is capable of moving forward and backward within the housing and has a cylindrical portion that extends slidably through the rear wall of the housing and protrudes outside the housing; a diaphragm having a portion fixed to the power piston and a peripheral edge portion fixed to the housing; a front chamber defined within the housing by the diaphragm and the power piston and constantly communicating with a negative pressure source; A rear chamber is defined in the housing by a diaphragm and the power piston, and air is caused to flow into the rear chamber in response to depression of a brake pedal to advance the power piston and to advance the power piston in response to release of the brake pedal. The power piston is equipped with a control valve that allows the atmosphere in the rear chamber to flow out into the front chamber and retracts the power piston, and a master cylinder pressing rod that slidably penetrates the front wall of the housing and protrudes outside the housing. The control valve includes a valve body that is slidably disposed within the power piston and is connected to the brake pedal via a rod that projects rearward from a rear end opening of the cylindrical portion. The sliding amount of the valve body with respect to the power piston is determined by a locking piece that is inserted into a radial passage provided in the power piston and whose inner end engages with a circumferential groove on the outer periphery of the valve body. In a brake booster, the locking piece is prevented from coming off from the radial passage hole by engagement between the inner circumferential edge of the diaphragm and the outer end of the locking piece. , the radial passage hole is provided closer to the rod than the inner circumferential edge of the diaphragm in the sliding direction of the valve body, and the locking piece is provided with an outer end extending forward to the outer circumference of the power piston. The diaphragm has an L-shaped bent claw that extends through the formed notch to the inner diameter side of the inner peripheral edge of the diaphragm, and the bent claw prevents the locking piece from coming off from the radial through hole. A brake booster characterized in that the brake booster is operated by engagement between a tip of the section and an inner circumferential edge of the diaphragm.