JPH0634201Y2 - Booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a booster, and more particularly to a booster including a diaphragm that defines a constant pressure chamber and a variable pressure chamber inside a shell.

"Prior Art" Conventionally, brake boosters and clutch boosters are generally
A power piston slidably disposed in the shell, a valve mechanism housed in the valve body of the power piston shaft, and a constant pressure chamber and a variable pressure chamber attached to the rear surface of the power piston are provided in the shell. It is provided with a diaphragm that defines it, and an input shaft that operates the valve plunger that constitutes the above-mentioned valve mechanism to switch the flow path and supplies pressure fluid to the above-mentioned variable pressure chamber to advance the power piston.

The inner periphery of the diaphragm is a power piston,
The outer peripheral portions are respectively connected to the shell, and bulge in a U-shaped cross section from the variable pressure chamber side to the constant pressure chamber side between the power piston and the shell. When the pressure fluid is introduced into the variable pressure chamber and the power piston is advanced, the diaphragm receives the pressure of the pressure fluid and comes into contact with the inner peripheral surface of the shell sequentially as the power piston advances, while When the power piston is retracted, the diaphragm is gradually separated from the inner peripheral surface of the shell as the power piston retracts.

"Problems to be solved by the invention" However, in the conventional booster, the boosting load is constant over the stroke range of the power piston,
For example, the boosting load cannot be changed between the first half and the second half of the stroke range.

As a result, in the clutch, the depression force of the clutch pedal is usually light after the clutch is disengaged, but in the conventional clutch booster, the boost load is constant even after the clutch is disengaged. With a clutch booster with a large boosting load, the clutch pedal force was too light, which could give a strange feeling.

In view of such circumstances, the present invention provides a booster capable of changing the boosting load within the stroke range of the power piston.

[Means for Solving the Problems] That is, the present invention is directed to the forward side of the power piston in the shell within the contact / separation range of the diaphragm which is in contact with / separated from the inner peripheral surface of the shell as the power piston moves back and forth. Is formed with a small diameter and a large diameter on the retracted side.

[Operation] In the booster configured as described above, the fluid pressure acts on the pressure receiving area between the power piston and the diaphragm to obtain the thrust of the power piston, but as described above, the shell moves as the power piston moves forward and backward. If a step is formed on the shell within the contact / separation range of the diaphragm that is contacted / separated from the inner peripheral surface of the, the pressure receiving area of the diaphragm can be changed before and after the step, and the thrust of the power piston can be changed accordingly.
Therefore, the boosting load can be changed within the stroke range of the power piston.

Therefore, for example, in the case of the clutch booster described above, the inner diameter of the shell is large at the position before the clutch is disengaged, and the inner diameter of the shell is small at the position after the clutch is disengaged. Since it can be made smaller, it is possible to prevent the clutch pedal force from becoming too light.

[Embodiment] The present invention will be described below with reference to an illustrated embodiment. In FIG. 1, a power piston 2 is slidably provided in a shell 1 of a clutch booster, and a diaphragm 3 is provided on a back surface of the power piston 2. The power piston 2 and the diaphragm 3 are provided so as to partition the inside of the shell 1 into a front constant pressure chamber 4 and a rear variable pressure chamber 5. The diaphragm 3 has an inner peripheral portion sandwiched between the power piston 2 and the valve body 6, and an outer peripheral portion connected to the shell 1, and the diaphragm 3 transforms between the power piston 2 and the shell 1. From the chamber 5 side to the constant pressure chamber 4
It bulges out in a U-shaped cross section.

A valve mechanism 7 for switching a flow path is housed in the valve body 6 provided integrally with the shaft portion of the power piston 2.
The valve mechanism 7 includes a first valve seat 10 formed on the valve body 6,
A second valve seat 12 formed on the valve plunger 11 and both valve seats 10,
The valve body 14 is provided with a valve body 12 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. Then, the constant pressure chamber 4 is provided through a passage 15 formed in the valve body 6 outside the seat portion of the first valve seat 10 and the valve body 14.
Further, the inside of the constant pressure chamber 4 is communicated with a negative pressure source such as an intake manifold of the engine through a negative pressure introducing pipe 16 provided in the shell 1.

On the other hand, the intermediate portion of each seal portion between the first valve seat 10 and the valve body 14 and the second valve seat 12 and the valve body 14 communicates with the variable pressure chamber 5 through a radial passage 17 formed in the valve body 6. Further, the inside of the seat portion of the second valve seat 12 and the valve body 14 is communicated with the atmosphere through an atmosphere passage 18 formed in the cylindrical portion 6a of the valve body 6.

The valve plunger 11 constituting the valve mechanism 7 is connected to an input shaft 22 which is interlocked with a clutch pedal (not shown), and an elastic force of a spring 23 provided between the valve body 6 and the input shaft 22 and a return of the clutch pedal (not shown). It is always urged to the right by the elastic force of the spring. The tip of the valve plunger 11 is connected to the output shaft via the reaction disc 24.
The output shaft 25 penetrates through the seal member 26 to project to the outside of the shell 1 in conjunction with 25, and also interlocks with a clutch mechanism (not shown).

The power piston 2 and the valve body 6 are usually
The return spring 27 holds the non-actuated position in the drawing. In this non-actuated state, the key member 28 for preventing the valve plunger 11 from coming out of the valve body 6 is brought into contact with the inner wall surface of the shell 1. The free rightward movement of the valve plunger 11 with respect to the valve body 6 is restricted so that the switching operation of the fluid circuit by the valve mechanism 7 can be immediately obtained when the input shaft 22 and the valve plunger 11 are operated next.

Further, on the outer peripheral surface of the shell 1, the power piston 2
Conical step 1a with a small diameter on the forward side and a large diameter on the backward side
Is formed. As can be seen from the imaginary line in FIG. 1, the step portion 1a is formed within the contact / separation range of the diaphragm 3 which is contacted / separated with the inner peripheral surface of the shell 1 as the power piston 2 moves back and forth. In addition, it is formed according to the position where the clutch is brought into contact with or separated from the clutch.

In the above configuration, when the clutch pedal (not shown) is stepped on and the input shaft 22 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 6 and the constant pressure chamber are The valve body 14 is separated from the second valve seat 12 of the valve plunger 11 so that 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 resilience of the return spring 27 due to the pressure difference before and after the power piston 2 as in the conventionally known clutch booster. The clutch is disengaged.

At this time, the diaphragm 3 receives the atmospheric pressure introduced into the variable pressure chamber 5 and sequentially comes into contact with the inner peripheral surface of the shell 1 as the power piston 2 moves forward. Since the front side of the step portion 1a is smaller than the rear side of the step portion 1a, when the power piston 2 moves forward and the contact position of the diaphragm 3 with the shell inner peripheral surface exceeds the step portion 1a, the diaphragm 3 moves. The pressure receiving area becomes smaller.

Therefore, since the forward force of the power piston 2 and the output shaft 25 becomes smaller due to the forward movement of the power piston 2, the boosting load becomes smaller before the clutch is disengaged and the clutch pedal force becomes lighter after the clutch is disengaged. It is possible to prevent overshooting.

On the other hand, when the depression force of the clutch pedal is released from the clutch disengaged state, the second valve seat 12 of the valve plunger 11 is seated on the valve body 14 to cut off the communication between the variable pressure chamber 5 and the atmosphere.
Since the valve body 14 is separated from the first valve seat 10 to communicate the variable pressure chamber 5 with the constant pressure chamber 4, the power piston 2 is returned to the original non-operating position by the return spring 27.

At this time, if the power piston 2 retracts and the contact position of the diaphragm 3 with the shell inner peripheral surface is on the rear side of the stepped portion 1a, the pressure receiving area of the diaphragm 3 becomes large, so the clutch is engaged. It is possible to ensure a good clutch operation feeling without the clutch pedal force becoming too heavy afterwards.

[Advantage of Invention] As described above, according to the present invention, the boosting load can be clearly changed between the start position and the end position of the stroke of the power piston by the step portion provided in the shell. It is possible to set a suitable boosting load before and after the engagement / disengagement of the clutch, thereby obtaining an effect that a suitable operation feeling can be secured.

[Brief description of drawings]

 FIG. 1 is a sectional view showing an embodiment of the present invention. 1 ... Shell, 2 ... Power piston 3 ... Diaphragm, 4 ... Constant pressure chamber 5 ... Transformer chamber, 6 ... Valve body 7 ... Valve mechanism, 22 ... Input shaft

Claims (1)

[Scope of utility model registration request] 1. A power piston slidably disposed in a shell, a valve mechanism housed in a valve body of a shaft portion of the power piston, and a constant pressure chamber provided in the shell on the rear surface of the power piston. And a diaphragm that defines a variable pressure chamber and an input shaft that operates a valve plunger that constitutes the valve mechanism to switch a flow path and supplies pressure fluid to the variable pressure chamber to advance a power piston. In the force device, within the contact / separation range of the diaphragm contacted / separated with the inner peripheral surface of the shell as the power piston moves forward / backward, the shell has a small diameter on the forward side of the power piston and a large diameter on the backward side. A booster having a step portion.