JP6097083B2 - Negative pressure booster - Google Patents

Description

  The present invention relates to a negative pressure booster used for boosting operation of a brake master cylinder of an automobile, and more particularly, to a booster shell and a front negative pressure chamber connected to a negative pressure source and a rear working chamber. A partitioning diaphragm is stretched, and a booster piston that operates a master cylinder attached to the booster shell by receiving a forward thrust of the diaphragm due to a pressure difference between the negative pressure chamber and the working chamber on a front surface of the diaphragm It is related with improvement of the negative pressure booster which piled up.

  Such a negative pressure booster is already known as disclosed in Patent Document 1.

Japanese Patent No. 4469316

  In such a negative pressure booster, when the forward thrust of the diaphragm due to the differential pressure between the negative pressure chamber and the working chamber is transmitted to the booster piston, the outer peripheral edge of the booster piston may bite into the diaphragm and damage the diaphragm. Therefore, conventionally, in order to prevent such damage to the diaphragm, the outer peripheral edge of the booster piston is formed in a bead shape having a cross-section arc, and the contact area between the outer peripheral edge and the diaphragm is widened, and the outer peripheral edge Does not cut into the diaphragm.

  However, in order to form the outer peripheral edge of the booster piston in a bead shape, a special bending process is required after punching the booster piston from the steel plate, which increases the manufacturing process of the booster piston and reduces costs. Hinder.

The present invention has been made in view of the mentioned circumstances, the outer periphery of the booster piston, even edge drop Ri Setsu have no bend, diaphragm, and so as not to be damaged by the cut off edge, Accordingly, an object of the present invention is to provide the negative pressure booster which can reduce the manufacturing process of the booster and can contribute to the cost reduction.

In order to achieve the above object, the present invention provides a booster shell with a diaphragm that divides the inside into a front negative pressure chamber and a rear working chamber connected to a negative pressure source. In the negative pressure booster in which a booster piston for operating a master cylinder attached to the booster shell is overlapped by receiving a forward thrust of the diaphragm due to a differential pressure between the negative pressure chamber and the working chamber, the booster the outer periphery of the piston, while forming an edge drop Ri Setsu have no bend, of the diaphragm, a flexure extending forward of the booster piston, the connecting portion between the piston pressing portion to be overlaid on the back of the booster piston, An annular thick part having a wall thickness larger than that of the bending part and the piston pressing part is formed, and an annular groove for embedding the outer peripheral edge of the booster piston is formed in the thick part. And wherein the digit.

According to a feature of the present invention, the outer peripheral edge of the booster piston, that has an edge drop Ri Setsu have no bend, it is possible to reduce the cost by reducing the manufacturing steps of the booster piston.

  In addition, an annular thick part having a wall thickness larger than that of the bending part and the piston pressing part is formed at the connection part between the bending part of the diaphragm and the piston pressing part, and the outer peripheral edge of the booster piston is held in this thick part. An annular groove is provided, so that when the diaphragm forward thrust due to the differential pressure between the negative pressure chamber and the working chamber is transmitted to the booster piston, it is highly elastic even if the outer peripheral edge of the booster piston bites into the thick part of the diaphragm The thick part will not be damaged.

  Furthermore, since the annular groove of the diaphragm embraces the outer peripheral edge of the booster piston, the booster piston and the diaphragm are always integrally connected to each other, so that not only the force transmission between the booster piston and the diaphragm is ensured. Even when the flexure portion of the diaphragm vibrates due to a sudden change in pressure between the negative pressure chamber and the working chamber, no deviation occurs between the booster piston and the diaphragm, and the durability of the diaphragm can be improved.

The longitudinal cross-sectional view of the negative pressure booster which concerns on embodiment of this invention. FIG. 2 is an enlarged view of part 2 of FIG. 1.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, in FIG. 1, the booster shell 1 of the negative pressure booster B is composed of a front shell half 1a and a rear shell half 1b that are each formed in a bowl shape and are connected to each other at opposite ends. The front shell half 1a and the rear shell half 1b are made of a steel plate, and they are coupled via a pair of steel tie rods 6 (only one of which is shown in FIG. 1). . The pair of tie rods 6 are arranged so as to sandwich the central axis of the booster shell 1, and by using these tie rods 6, a cylinder body of a brake master cylinder M for an automobile is formed on the front end surface of the front shell half 1a. Ma is fastened, and using these tie rods 6, the rear shell half 1b is fastened to the front surface of the vehicle body F of the automobile.

  The inside of the booster shell 1 is partitioned into a negative pressure chamber 2 on the front side and a working chamber 3 on the rear side by a diaphragm 5 sandwiched between the two shell halves 1a and 1b. A booster piston 4 capable of reciprocating back and forth within the booster shell 1 is disposed in an overlapping manner. The diaphragm 5 is integrally formed with a cylindrical slide seal 8 that passes through an intermediate portion of the booster piston 4 in an airtight manner and can slide on the tie rod 6.

  A resin valve cylinder 10 is integrally coupled to the central portions of the booster piston 4 and the diaphragm 5. The valve cylinder 10 is slidably supported via a bearing bush 9 on a bearing cylinder 12 protruding rearward from the center of the rear shell half 1b.

  The negative pressure chamber 2 is connected to a negative pressure source V (for example, inside the intake manifold of the internal combustion engine) via a negative pressure introduction pipe 14 and a check valve 19.

  At the rear end portion of the valve cylinder 10, an air introduction port 7 for introducing air into the valve cylinder 10 is provided. Further, in the valve cylinder 10, an input rod 20 connected to the brake pedal P, and a control valve for switching the working chamber 3 to the negative pressure chamber 2 and the atmosphere introduction port 7 in accordance with the longitudinal movement of the input rod 20. 11 is disposed. That is, the control valve 11 shuts off the working chamber 3 from the atmosphere introduction port 7 and communicates with the negative pressure chamber 2 when the input rod 20 moves backward, and connects the working chamber 3 and the negative pressure chamber when the input rod 20 moves forward. 2 and a known structure that can communicate with the air inlet 7. Between the input rod 20 and the valve cylinder 10, an input return spring 13 that biases the input rod 20 in the backward direction is contracted.

  The control valve 11 includes a valve piston 18 slidably fitted to the valve cylinder 10 and connected to the front end portion of the input rod 20. A reaction force piston 17 is formed at the front end of the valve piston 18. The

  A key member 23 is attached to the valve cylinder 10 so as to abut the front end portion of the bearing cylinder 12 and define the backward limit of the valve cylinder 10 and the input rod 20.

  The valve cylinder 10 is provided with an operating piston 15 that protrudes forward and a small-diameter cylinder hole 16 that penetrates the center of the operating piston 15, and the reaction-force piston 17 is slidable in the small-diameter cylinder hole 16. To be fitted. A cup body 21 is slidably fitted on the outer periphery of the working piston 15, and the cup body 21 is filled with a flat elastic piston 22 that faces the working piston 15 and the reaction force piston 17.

  An output rod 25 is connected to the front surface of the cup body 21. Therefore, the output rod 25 is slidably supported by the valve cylinder 10 via the cup body 21. This output rod 25 is connected to the rear end portion of the master piston Mb of the master cylinder M passing through the center portion of the front shell half 1a.

  In the above, the operation piston 15, the reaction force piston 17, the elastic piston 22, and the cup body 21 constitute a reaction force mechanism 24 that feeds back a part of the output of the output rod 25 to the input rod 20.

  Between the front wall of the booster shell 1 and the front end surface of the valve cylinder 10, a booster return spring 27 that urges the valve cylinder 10 in the backward direction is contracted.

As shown in FIG. 2, the outer peripheral edge 4a of the booster piston 4, the orゝwhen punched by press working the booster piston 4 from steel material, is an edge drop Ri Setsu have no bends. On the other hand, the diaphragm 5 includes a bent portion 5a extending forward from the outer peripheral end portion clamped by the front and rear shell halves 1a and 1b and then turning back to reach the outer peripheral portion of the booster piston 4. The piston pressing portion 5b is provided integrally with the portion 5a and overlaps the back surface of the booster piston 4. The connecting portion between the bending portion 5a and the piston pressing portion 5b has a thickness of the bending portion 5a and the connecting portion of the piston pressing portion 5b. An annular thick part 5c larger than the piston pressing part is formed, and an annular groove 28 for embedding the outer peripheral edge 4a of the booster piston 4 is formed in the thick part 5c.

  Next, the operation of this embodiment will be described.

  In the idle state of the negative pressure booster B, that is, in the released state of the input rod 20, the key member 23 attached to the valve cylinder 10 contacts the front end of the bearing cylinder 12, and the rear end face of the reaction force piston 17 is against this key member 23. The input rod 20 is in contact with the input return spring 13 and is held at the retreat limit. At this time, the control valve 11 blocks between the working chamber 3 and the air introduction port 7 and communicates between the working chamber 3 and the negative pressure chamber 2. Accordingly, the negative pressure in the negative pressure chamber 2 is transmitted to the working chamber 3 and the two chambers 2 and 3 have the same pressure. Therefore, the booster piston 4 and the valve cylinder 10 are held in the retracted position by the biasing force of the booster return spring 27. The

  When the input rod 20 is moved forward together with the valve piston 18 against the set load of the input return spring 13 by depressing the brake pedal P to brake the vehicle, the control valve 11 is moved to the working chamber 3 and the negative pressure chamber 2. Is communicated between the working chamber 3 and the air inlet 7. As a result, the atmosphere is introduced into the working chamber 3 from the atmosphere introduction port 7, and the working chamber 3 is set to a pressure higher than that of the negative pressure chamber 2, so that the diaphragm 5 obtains a forward thrust based on the pressure difference between the booster piston 4 and The valve cylinder 10, the working piston 15, the elastic piston 22, the cup body 21, the output rod 25, and the like are moved forward against the force of the booster return spring 27, so that the output rod 25 drives the master piston Mb forward, and the vehicle The brake can be activated.

  When the output rod 25 is actuated, the reaction force compresses the elastic piston 22, and a part thereof bulges into the small diameter cylinder hole 16 and abuts against the reaction force piston 17. According to this contact, a part of the reaction force of the output rod 25 is fed back to the input rod 20 via the elastic piston 22, so that the operator can feel the magnitude of the output of the output rod 25. be able to. The output of the output rod 25 increases with a boost ratio determined by the ratio of the pressure receiving areas of the working piston 15 and the reaction force piston 17 that are in contact with the elastic piston 22.

  After reaching the boost limit point at which the pressure difference between the negative pressure chamber 2 and the working chamber 3 reaches the maximum, the output of the output rod 25 is the maximum thrust generated by the booster piston 4 due to the pressure difference and the input to the input rod 20. This is the sum of the operation input.

  When the pedaling force is released from the brake pedal P to release the brake operating state of the vehicle, the input rod 20 and the valve piston 18 are first moved backward by the force of the input return spring 13. Accordingly, the control valve 11 blocks the working chamber 3 from the atmosphere introduction port 7 and communicates with the negative pressure chamber 2, so that introduction of the atmosphere into the working chamber 3 is prevented, while the air in the working chamber 3 is blocked. Is sucked into the negative pressure limit V through the negative pressure chamber 2 and the pressure difference between them is eliminated. Therefore, the booster piston 4 is also retracted by the elastic force of the booster return spring 27 and the operation of the master cylinder M is released. . Then, the key member 23 attached to the valve cylinder 10 contacts the front end of the bearing cylinder 12 as described above, so that the booster piston 4 and the input rod 20 return to the resting state again.

  By the way, when the forward thrust of the diaphragm 5 due to the differential pressure between the negative pressure chamber 2 and the working chamber 3 is transmitted to the booster piston 4, the outer peripheral edge 4 a of the booster piston 4 is the bent portion 5 a of the diaphragm 5 and the piston. Although it will bite into the thick part 5c formed in the connection part of the press part 5b, the thick part 5c rich in elasticity is not damaged by the said outer periphery 4a.

  Further, since the annular groove 28 of the thick part 5c of the diaphragm 5 embraces the outer peripheral edge of the booster piston 4, the booster piston 4 and the diaphragm 5 are always integrally connected to each other, and between the booster piston 4 and the diaphragm 5 Not only is the force transmitted reliably, but even when the bending portion 5a of the diaphragm 5 vibrates due to a sudden change in pressure between the negative pressure chamber 2 and the working chamber 3, a deviation occurs between the booster piston 4 and the diaphragm 5. Therefore, the durability of the diaphragm 5 can be improved.

The outer peripheral edge 4a of the booster piston 4, by being an edge drop Ri Setsu have no bend, it is not necessary to apply a special bending the outer peripheral portion of the booster piston 4, to reduce the manufacturing steps of the booster piston 4 The cost can be reduced.

  The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention. For example, the front and rear shell halves 1a and 1b are caulked and joined to each other without using the tie rod 6, and the rear shell half 1b is fixed to the vehicle body F with dedicated bolts. A master cylinder M can also be attached to the body 1a.

B ... Negative pressure booster M ... Master cylinder 1 ... Booster shell 2 ... Negative pressure chamber 3 ... Working chamber 4 ... Booster piston 4a ... Booster piston Outer peripheral edge 5 ··· diaphragm 5a · flexure portion 5b · piston pressing portion 5c · thick portion 28 · · · annular groove

Claims (1)

The booster shell (1) is provided with a diaphragm (5) which is divided into a front negative pressure chamber (2) and a rear working chamber (3) connected to the negative pressure source (V). A master cylinder attached to the booster shell (1) receives the forward thrust of the diaphragm (5) due to the differential pressure between the negative pressure chamber (2) and the working chamber (3) on the front surface of (5) In the negative pressure booster in which the booster piston (4) for operating (M) is arranged in an overlapping manner,
Wherein the outer peripheral edge of the booster piston (4) (4a), while forming an edge drop Ri Setsu have no bend, the diaphragm (5) of the booster piston (4) bending portion extending forwardly of (5a), An annular thick part (5c) whose thickness is larger than that of the bending part (5a) and the piston pressing part (5b) at the connection part with the piston pressing part (5b) superimposed on the back surface of the booster piston (4). The negative pressure booster is characterized in that an annular groove (28) for embedding the outer peripheral edge (4a) of the booster piston (4) is provided in the thick part (5c).

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