JPS60154949A - Brake booster - Google Patents

Abstract

PURPOSE:To prevent shock noise by contacting a springboard for energizing a plunger against the inner face of housing under returning stroke of power piston thereby reducing the energizing force of spring then advancing the plunger and reducing the opening of valve. CONSTITUTION:Upon release of brake, power piston will return to retract a plunger 20 through energizing force of springboard 39. Retraction of plunger 20 is blocked through contact of the front wall face 44 of annular groove 37 in the plunger 20 against a retraction limiting board 38. Upon complete returning of power piston 5, the contact portion 39f of springboard 39 will contact against the retainer 41 of rear housing 2 to reduce the energizing force of spring 39 against the plunger 20. Consequently, the plunger 20 will advance to reduce the gap of first valve 18 from C1 to C2, thus to reduce the loss stroke of pedal. While upon contact of said portion 39f against the retainer 41, shock force is absorbed by the springboard 39 to prevent shock noise.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake booster, and more particularly, to a brake booster in which a leaf spring is disposed on a power piston, a part of which contacts a valve opening/closing plunger and urges the plunger in a cold-weather backward direction. Regarding booster.

In this type of brake booster, a power piston that suppresses a mask cylinder piston is arranged in a housing so as to be able to reciprocate, and a constant pressure chamber and a variable pressure chamber are respectively formed before and after the power piston. Inside, a first on-off valve opens and closes a communication path between the constant pressure chamber and the variable pressure chamber, and a second on-off valve opens and closes a communication path between the variable pressure chamber and the atmosphere, and the first on-off valve opens and closes the communication path between the variable pressure chamber and the atmosphere. The first and second on-off valves are slidably disposed within the power piston and are controlled to open and close by advancing and retracting a plunger connected to a brake pedal via an operating rod. In other words, in a vacuum type booster, negative pressure is constantly introduced into the constant pressure chamber, and when the brake pedal is depressed and the operating iron is moved forward, the plunger moves forward and the first on-off valve is closed. At the same time, the second on-off valve opens and atmospheric pressure is introduced into the variable pressure chamber, and this atmospheric pressure causes the power piston to move forward. In addition, when the brake pedal is released, the operating iron moves back by the return spring, the plunger retreats, the first on-off valve is released, and the second on-off valve is closed, causing pressure in the constant pressure chamber and variable pressure chamber. The difference is eliminated, and the power piston is now able to move back with the force of its return spring.

By the way, it is best to make the opening degree or gap of the first on-off valve as large as possible during the backward movement of the power piston, so that the pressure difference between the constant pressure chamber and the variable pressure chamber is quickly eliminated, and the power is increased. Quick return movement of the piston is possible. On the other hand, when the power piston completes its backward movement, the above-mentioned gap becomes a loss stroke of the operating rond, so it is best to keep it as small as possible.

A brake booster that satisfies both of these conflicting demands has already been proposed in Japanese Patent Publication No. 45379/1983. In this booster, the retraction limit of the plunger relative to the power piston is inserted into a radial hole formed in the power piston, and the inner end is engaged with an annular groove formed on the outer circumferential surface of the plunger. The radial hole is formed so that the retreat regulating plate can move back and forth within a predetermined range with respect to the power piston, and the retreat regulating plate has the ability to move forward and backward of the power piston.
A contact portion is formed that separates from and comes into contact with the inner surface of the rear wall of the housing due to the backward movement to restrict the front-rear position of the retreat restriction plate within the radial hole.

However, in such a booster, the retreat restriction plate that regulates the retreat limit of the plunger is movable by a predetermined amount in the front and back direction within the radial hole, so that when the plunger retreats due to the force of the return spring, the The regulating plate rattles within the radial hole. Because of this rattling, the retreat regulating plate and the plunger come into contact with each other in a distorted state, and as a result, part of the force of the return spring becomes a radial force that reflexively acts on the plunger, causing the axis of the plunger to This may cause uneven wear on the outer circumferential surface of the plunger, which may shorten the life of the brake booster.

In addition, the speed of the power piston's backward movement is determined by the opening degree of the first on-off valve, that is, the retraction limit of the plunger. It must be kept constant. For this reason, in conventional boosters, the thickness or rigidity of the retreat regulating plate is made large enough to withstand the force of the return spring of the plunger. However, when such a highly rigid backward restriction plate is used, impact noise is likely to be generated when the abutting portion of the backward restriction plate comes into contact with the inner surface of the rear wall of the housing, and The plate increases weight and cost.

The present invention was developed in view of the above circumstances, and its purpose is to reduce the loss and stroke of the operation iron, and furthermore, when the plunger retreats, no lateral load acts on the plunger. It is an object of the present invention to provide a brake booster capable of preventing the generation of impact noise when a power piston moves back. A constant pressure chamber and a variable pressure chamber are formed before and after the power piston, and inside the power piston, a first on-off valve opens and closes a communication path between the constant pressure chamber and the variable pressure chamber, and a first on-off valve that opens and closes a communication path between the constant pressure chamber and the variable pressure chamber, and a and second on-off valves for opening and closing communication passages with the power piston, and the first and second on-off valves are slidably disposed within the power piston and connected to the brake pedal via an operating rod. In a brake booster whose opening and closing are controlled by advancing and retracting connected plungers, an insertion hole extending radially outward from a housing hole of the plunger is formed in the power piston, and the insertion hole is connected to the insertion hole. a leaf spring, a portion of which engages with the plunger and constantly biases the plunger in the backward direction;
is inserted, and at the same time, forming a contact part on another part of the leaf spring that comes into contact with the inner surface of the rear wall of the housing during the return movement of the power piston to reduce the biasing force of the leaf spring,
When the retraction limit of the plunger is restricted by the retraction restriction plate and the power piston moves backward, the abutting portion of the leaf spring is brought into contact with the inner surface of the rear wall of the housing, and the 1114, the brake booster is configured to reduce the force, thereby moving the plunger forward relative to the power piston, thereby reducing the opening degree of the first on-off valve. .

An embodiment in which the present invention is applied to a vacuum type brake booster will be described below with reference to the drawings.

Figure 1 shows a longitudinal section of the brake booster. In the figure, 1 is a front housing, 2 is a rear housing, and these housings 1 and 2 are fitted together to form a sealed type. A housing 3 is formed. The diaphragm 4 has its outer peripheral thick part 4a connected to both the housings 1 and 2.
is fixed between the fitting surfaces of the housings 1 and 2, thereby sealing the fitting surfaces of the housings l and 2. Further, the inner peripheral thick portion 4b of the diaphragm 4 is hermetically fitted into the outer peripheral groove 6 of the power piston 5. Inside the housing 3 is a constant pressure chamber 7 formed by a diaphragm 4 and a power piston 5.
It is divided into two chambers, front and rear of the transformation chamber 8. Note that the power piston 5 is always moved in the backward direction by the return spring 15.
(to the right in the figure), and the return movement of the power piston 5 is prevented by the stopper portion 4c of the diaphragm 4 coming into contact with the inner surface of the rear housing 2.

The power piston 5 integrally has a cylindrical valve body 9 on its rear side, and this valve body 9 slidably passes through the rear housing 2. Also, power piston 5
A bushing rod 11 attached to one end of the bushing rod 11 slidably passes through the front housing link 1. The sliding surfaces of the valve body 9 and bushing rod J1 are sealed by seals IA and 14, respectively.

Inside the valve body 9, there are a first on-off valve 18 that opens and closes a communication path between the constant pressure chamber 7 and the variable pressure chamber 8, and a second on-off valve 19 that opens and closes a communication path between the variable pressure chamber 8 and the atmosphere. Each is built-in. These two on-off valves 18 and 19 are
Opening and closing are controlled by the forward and backward movement of a plunger 20 that is slidably disposed inside the power piston 5. Note that this plunger 20 has a reaction plate 1 made of rubber.
6 and transmission plate 17. It is connected to Pushi 10 and Sodo 11 with the two in between.

Specifically, the tip of the operating rod 21 connected to a brake pedal (not shown) connects to the plunger 2 via a ball joint 22.
Connected to 0. An annular seat is formed at the rear end of the plunger 20, and an annular rubber poppet valve 24 is disposed behind the seat. The poppet valve 24 and the seat portion of the plunger 20 constitute a second on-off valve 19. On the other hand, an annular seat portion is formed on the inner peripheral wall of the valve body 9 in front of the poppet valve 24, and the first on-off valve 18 is constituted by this seat portion and the poppet valve 24. The poppet valve 24 is always urged forward by a compression spring 25, and this force (=1) always closes the second on-off valve 19 (when the power piston 5 completes its return movement), and the first The on-off valve 18 is opened with a predetermined gap maintained.

The outer peripheral space 28 of the poppet valve 24 is communicated with the constant pressure chamber 7 via a communication passage 29 formed within the power piston 5. Further, the outer circumferential space 30 of the plunger 20 is communicated with the variable pressure chamber 8 via a communication passage 31 similarly formed within the power piston 5. Therefore, when the first on-off valve 18 opens, the constant pressure chamber 7 and the variable pressure chamber 8 communicate with each other through the communication passage 29.31, and when the second on-off valve 19 opens, the communication passage 31 and the passage in the valve body 9 communicate with each other. 32 allows the variable pressure chamber 8 and the atmosphere to communicate with each other. Note that an air filter 33 is disposed within the passage 32.

An annular groove 37 is formed in the outer circumferential surface of the plunger 20, and the upper end portion of a retreat regulating plate 38 is engaged with the annular groove 37 with a predetermined gap maintained in the front-rear direction. This retreat restriction plate 38 is fixedly inserted into an insertion hole 36 formed in the half-i direction of the power piston 5, and is configured to restrict the retreat limit of the plunger 20 when the power piston 5 moves backward. It has become. On the other hand, a leaf spring 39 clearly shown in FIG. 2 is inserted into the communication path 31. This leaf spring 39 is formed by bending a single metal plate punched out using a press, and has a pair of left and right spring parts 39a formed at its upper end. This pair of spring parts 39a should
A pair of L-shaped retaining parts 39b extending forward are formed at the distal ends of the retaining parts 39b. The pair of engaging portions 39b are inserted into the left and right sides of an annular groove 40 formed on the outer periphery of the ball joint portion of the plunger 20, as shown in FIGS. It is always energized in the backward direction.

Further, a pair of left and right locking portions 39c bent into a U-shape is formed in the middle portion of the leaf spring 39.
is fixedly inserted into the communication path 31. In addition, the center of the intermediate part of the leaf spring 39 is folded downward to form a folded part 39c.
After forming the
A letter-shaped contact portion 39f is formed. This contact portion 39f
When the power piston 5 moves (k), it comes into contact with the retainer 41 of the seal 13, thereby causing the pair of spring portions 39a to move 1 (1 (
The force is decreasing.

The brake booster is constructed as described above, and the constant pressure chamber 7 is connected to the intake port of the engine (not shown) through the gold pipe 42 and tube 43 as shown in FIG. Negative pressure is introduced.

On the other hand, when the brake booster is not operating, the force of 1 (11) of the leaf spring 39 acts on the poppet valve 24, and the first opening/closing valve 18 resists the compression spring 25 as shown in FIG. At this time, the negative pressure in the constant pressure chamber 7 is also introduced into the variable pressure chamber 8 through the communication passages 29 and 31, and both chambers 7°8
Since there is no pressure difference, the power piston 5 moves back to the right as shown in FIG. 1 by the force of the return spring 15.

Next, when the brake pedal is depressed and the operating rod 21 is moved forward in the left direction in FIG. 1 against the leaf spring 39, the plunger 20 is moved forward in the left direction in FIG. is closed by the biasing force of the compression spring 25, and
The plunger 20 and the poppet valve 24 are separated, and the second on-off valve 19 is opened. Therefore, the outside air that has passed through the air filter 33 passes through the passage 32 and the communication passage 31 to the variable pressure chamber 8.
The power piston 5 moves forward against the return spring 15 due to the pressure difference between the constant pressure chamber 7 and the variable pressure chamber 8.

At this time, a part of the reaction force of the psoschrond 11 is transmitted to the operating rod 21 via the reaction plate 16 and the transmission plate 17, so that the reaction force proportional to the braking force is sensed by the driver as the brake pedal depression force. .

Next, when the brake pedal is released, the plunger 20 is moved backward by the biasing force of the leaf spring 39 as shown in FIG. For this reason, the seat portion of the plunger 20 is pressed against the poppet valve 24, and the second on-off valve 19 is closed again, and the first on-off valve 18 is opened, and the air in the variable pressure chamber 8 is transferred to the communication path 3L 29 and the constant pressure. It is sucked out through the chamber 7 to the intake port of the engine. As a result, the pressure difference between the two chambers 7.degree. 8 is reduced, and the power piston 5 is moved back by the return spring 15.

At this time, the speed of the return movement of the power piston 5 is proportional to the rate of decrease in the pressure difference between the two chambers 7 and 8, assuming that the centrifugal force of the return spring 15 is constant. The larger the gap C1 is, the faster the power piston 5 moves back. This gap C3 is determined by the retracted position of the plunger 20, but in the booster according to the present invention, the retracted position of the plunger 20 is restricted by the retracting restriction plate 38, so that no excessive force is applied to the plunger 20. It does not work, and the device is extremely durable.

When the plunger 20 retreats due to the biasing force of the leaf spring 39, the front wall surface 44 of the annular groove 37 engages with the retreat regulating plate 3.
8 and prevents the plunger 20 from retreating. However, since the retreat restriction plate 38 is fixedly inserted into the insertion hole 36 of the power screw I/N 5, it does not wobble at all even if the plunger 20 comes into contact with it. Never. Therefore, unlike conventional boosters, no excessive force is applied in the radial direction to the plunger 20.

Next, when the power piston 5 moves back completely, the contact portion 39f of the leaf spring 39 comes into contact with the retainer 41 attached to the rear housing 2, as shown in FIG. Reduce the auxiliary forces in the retreat direction. As a result, the plunger 20 moves forward slightly due to the atmospheric pressure acting on its ball joint, and the gap of the first on-off valve 18 decreases from <C+ to C2 as shown in FIG. 4. Therefore, when the operating rod 21 is moved forward again from the state shown in FIG.
can be closed and the second on-off valve 19 can be opened, and the loss and stroke of the operating rod 21 can be extremely small. Note that the contact portion 39f of the leaf spring 39 is connected to the retainer 4.
1, the folded portion 39e elastically deforms slightly forward as shown in FIG. 4 and absorbs the impact force at the time of contact, so there is no risk of impact noise occurring when the power piston 5 moves back. Not at all.

Note that when the power piston 5 fully moves back, the stopper portion 4c of the diaphragm 4 comes into contact with the inner surface of the rear housing 2 and supports the power piston 5, as shown in FIG. This prevents the leaf spring 3 from exerting an excessive force on the spring 39.
By increasing the elasticity of 9, it is possible to effectively prevent the above-mentioned impact noise from occurring. Furthermore, since the return position of the power piston 5 is regulated by the stopper portion 4c of the diaphragm 4, the gap C2 of the first on-off valve 18 shown in FIG. can be kept to a minimum.

The first embodiment of the present invention has been described above, and next, the second embodiment of the present invention will be described based on FIGS. 5 and 6. This second embodiment is similar to the leaf spring 39 in the first embodiment.
The difference is that another leaf spring 47 is used instead of. Specifically, as shown in FIG. 6, the lower end of the leaf spring 47 is bent into a U-shape to form a locking portion 47c.
7c is fixedly inserted into the communication path 31 of the power piston 5. The intermediate portion of the leaf spring 47 is formed with a pair of left and right spring portions 47a that are slightly bent toward the rear, and an engaging portion 47b that protrudes toward the front.
7a and the engaging portion 47b are inserted into the annular groove 40 of the plunger 20, and the plunger 20 is then urged in the backward direction by the pair of spring portions 47a. Further, a pair of left and right abutting portions 47f extending further upward is formed at the upper ends of the pair of spring portions 47a, and the pair of abutting portions 47f connect to the communication passages 47f that are separately formed in the power piston 5.
8 so that it can move back and forth. When the power piston 5 fully moves back, the pair of abutting portions 47
As shown in FIG. 5, the point f comes into contact with the inner surface of the rear housing 2 to reduce the biasing force of the pair of spring portions 47a against the plunger 20 in the backward direction.

More. In the brake booster constructed as in J-, the shape of the leaf spring 47 is different from that of the first embodiment, but the operating state etc. are completely the same as in the first embodiment, so a description thereof will be omitted.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. For example, in the above embodiment, the leaf spring 39 or 47 is provided in the communication path 31.
was inserted and its spring portion 39a or 47a was engaged with the plunger 20. However, an insertion hole (not shown) is separately formed in the power screw I/N 5, and the leaf spring 39 or 47 is inserted through this insertion hole. Good too. Also leaf spring 39.4
The shape of 7 is not limited to the shape shown in the above embodiment, and various shapes can be adopted. Furthermore, the present invention is applicable not only to vacuum type boosters but also to positive pressure type boosters.

As described above, when the power piston moves back, the present invention
The contact portion of the leaf spring that urges the plunger in the backward direction is brought into contact with the inner surface of the rear wall of the housing to reduce the urging force of the leaf spring, thereby causing the plunger to move relative to the power piston. Since the opening of the first on-off valve is reduced by moving the plunger forward, the retracting position of the plunger can be surely regulated by the retracting regulating plate without causing any twisting between the plunger and the retracting regulating plate. This eliminates the need for excessive force in the radial direction to act on the plunger, which is the case with conventional boosters. Therefore, when the plunger retreats, its axis does not change (tri Since it is possible to reduce the opening degree of the first on-off valve by reducing the biasing force, it is possible to reduce the loss and stroke of the operation iron, and also to reduce the opening degree of the first on-off valve during the return movement of the power piston. The opening degree of the on-off valve can be made relatively large, and rapid return movement of the power piston can be realized.

Furthermore, even if the contact portion of the leaf spring contacts the inner surface of the rear wall of the housing, the impact force at this time is absorbed by the elastic force of the handling spring, so there is no risk of impact noise being generated.

Furthermore, since the above-mentioned leaf spring also serves as a return spring for the plunger, the return spring for the plunger, which was removed from the operating rod in conventional boosters, is no longer required, and the structure of the brake booster can be improved. Simplification or cost reduction and shortening of the axial length of the device can be achieved.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view of a brake booster, FIG. 2 is a perspective view of a leaf spring, and FIG. 3 is a perspective view of a leaf spring. FIG. 4 is a vertical cross-sectional view of the plunger and its surroundings during the rhythmic movement of the power piston, and is a vertical cross-sectional view similar to FIG. 3 when the power piston completes its backward movement. 5 and 6 show a second embodiment of the present invention, in which FIG. 5 is a longitudinal sectional view of a brake booster, and FIG. 6 is a perspective view of a leaf spring. 1...Freon 1-housing, 2...Rear housing, 3...Housing, 4...Diaphragm, 5
... Power piston, 7... Constant pressure chamber, 8... Variable pressure chamber, 11... Bush rod, 18... First on-off valve, 19... Second on-off valve, 20... Plunger, 21... Operating rod, 29, 31... Communication passage, 32... Passage, 33... Air filter, 3
6...insertion hole, 37, 40...annular groove, 38...
・Backward restriction plate, 39, 47...plate spring, 39a,
47r+...Spring part, 39b, 47b...Engaging part, 39f, 41f...Abutting part, 44...Front wall surface of the annular groove 37. 2nd @ 3rd prisoner Figure 6 Figure 4 Procedural amendment (Own ship Applicable date of April 1980 Kazuo Wakasugi, Commissioner of the Patent Office 1, Indication of the case 1989 Patent Application No. 9740 2, Title of the invention Brake booster 3, relationship with the case of the person making the amendment Patent applicant name Jidosha Kiki Co., Ltd. 4, agent 〒107 Contents of amendment (1) Page 10 of the specification, line 13 “Sare ni j 1 - Further (2) On page 16, line 4, ``Rurukara'' is corrected to ``Arukara''.

Claims (1)

[Claims] A power piston that presses the mask cylinder piston is arranged in a housing so as to be able to reciprocate, and a constant pressure chamber and a variable pressure chamber are respectively formed in front and behind the power piston, and the constant pressure chamber and variable pressure chamber are formed inside the power piston. A first on-off valve that opens and closes a communication path between the variable pressure chamber and the atmosphere, and a second on-off valve that opens and closes a communication path between the variable pressure chamber and the atmosphere are respectively provided,
The first and second on-off valves are slidably disposed within the power piston and are controlled to open and close by advancing and retracting a plunger connected to the brake pedal through one operation. , an insertion hole extending radially outward from the accommodation hole of the plunger is formed in the power piston, and a portion of the insertion hole engages with the plunger to move the plunger in a backward direction during suspension. In addition to inserting a leaf spring that energizes the leaf spring, another part of the leaf spring is provided with an abutting part that comes into contact with the inner surface of the rear wall of the housing when the power piston moves back and reduces the energizing force of the leaf spring. When the power piston moves back,
``2. The contact portion of the handling spring is brought into contact with the inner surface of the rear wall of the housing to reduce the biasing force of the leaf spring, thereby moving the ``2. plunger forward relative to the power piston.'' A brake booster characterized in that the brake booster is configured to reduce the opening degree of the first on-off valve.