JP2002250366A - Master cylinder for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent transmission of hydraulic pulsation caused by engine vibration and the like from a master cylinder to other members. SOLUTION: Elastic members 25 and 29 are arranged in a space between a pressure chamber 8 within a housing 10 and a reservoir port 12. A first sealing member 20 and support rings 21 and 28 are made free vibration states according to a hydraulic fluctuation of the pressure chamber 8 against elastic forces of the elastic members 25 and 29.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a master cylinder used for a clutch or a brake system of a vehicle.

[0002]

2. Description of the Related Art A master cylinder is used to convert the depressing force applied to a pedal provided on a vehicle into a fluid pressure, and to use the fluid pressure for brake and clutch operations. The master cylinder has a configuration in which a piston is slidably disposed in a central bore of a housing having an output port and a reservoir port, and the piston is operated by a push rod reciprocated by a brake pedal or a clutch pedal. Pushing the piston into the central bore increases the fluid pressure (generally oil pressure) in the pressure chamber in the central bore. This increased oil pressure is used for brake and clutch operations.

When this type of master cylinder is used in, for example, a clutch system, a piston is slid by a push rod connected to a clutch pedal, and oil as a pressure medium is fed to a release cylinder by pressure.
It is possible to operate the connection and disconnection of the clutch. But,
In the release cylinder attached to the transmission directly connected to the vehicle engine, a slight stroke vibration occurs due to the engine vibration, which propagates to the master cylinder as hydraulic pulsation, and is transmitted to the clutch pedal via the piston and the push rod. Unpleasant vibrations may cause discomfort to the feet of the occupant, and may further resonate in the cabin and cause unpleasant noise. For this reason, a mechanism for reducing abnormal noise and vibration due to such hydraulic pulsation is essential.

In order to solve this problem, Japanese Utility Model Application Laid-Open No. 53-745 has been proposed.
No. 46, Japanese Utility Model Application Laid-Open No. 62-147793, and Japanese Utility Model Application Laid-open No. 61-131591 propose a hydraulic pulsation absorbing device set in a pipe connecting a master cylinder and a release cylinder. Each of them has an elastic member such as a diaphragm or a rubber cushion inside, and reduces the pulsation by changing the volume occupied by the pressure medium in accordance with the hydraulic pulsation, attenuating abnormal noise and vibration, as described above. Trying to solve the problem. However, these hydraulic pulsation absorbers have elastic members, pressure receiving members,
Requires a special housing to store sealing members, etc.
There is a problem that the cost becomes high as a system.

[0005] Apart from this, German Patent Publication DE 19
Japanese Patent No. 516391A1 proposes a structure in which a vibration absorbing device made of an elastic member is provided at a joint between a piston and a push rod of a master cylinder. However, in the vehicle specification where the pressure receiving size of the master cylinder must be set to a small diameter in order to reduce the pedaling force, the inside of the piston has a very small diameter and the spring constant of the elastic member housed inside must be set low. However, there is a problem that the loss stroke becomes large because of the absence. In addition, since the clutch pedal moves in an arc and it is necessary to allow the swing angle at the contact portion between the piston and the rod, this structure may cause uneven contact with the elastic member and the original characteristics may not be obtained. There is.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art.

[0007]

Means for Solving the Problems The present invention basically comprises:
Means is provided for disposing an elastic member between a pair of seal members in a space connecting the pressure chamber in the housing and the reservoir port and slidingly contacting the outer peripheral surface of the piston. The adoption of this means absorbs the change in volume of the pressure chamber by sliding of the seal member and elastic deformation of the elastic member, thereby preventing generation of pulsation of fluid pressure and transmission to the occupant.

According to the present invention, there is provided a housing having an output port, a reservoir port, and a central bore, and a piston for receiving a pedal depressing force so as to be slidable in the axial direction in the central bore and forming a pressure chamber in the central bore. A first seal member disposed in a space between the pressure chamber and the reservoir port and slidably contacting the outer peripheral surface of the piston; and a first seal member disposed in a space between the reservoir port and the opening side of the central bore and sliding on the outer peripheral surface of the piston. A master cylinder for a vehicle, comprising: a second seal member in contact with the support member, a support ring disposed between the two seal members and supporting the first seal member, and a guide sleeve fixed to the housing and surrounding the piston. An elastic member is disposed between the support ring and the housing, and the elastic member is connected to the first seal member and the support ring in response to pressure pulsation of the pressure chamber. Elastically deformed so as to permit axial sliding, the vehicle master cylinder, characterized in that to vary the volume of the pressure chamber is provided.

According to the present invention, a pulsation absorbing effect due to a change in the volume of the oil chamber can be obtained only by adding an elastic member and a holding member inside the master cylinder. Cost. Also,
An elastic member can be provided on the outer peripheral surface of the piston, so the storage space can be secured without depending on the cylinder size, so that the characteristics of the elastic member can be set freely and the contact structure between the piston and the rod is spherical as in the past. , The swing angle of the rod accompanying the arc movement of the pedal can be allowed. Furthermore, since the elastic member is provided inside the master cylinder, there is no increase in the loss stroke due to buckling at the time of compressing the elastic member as seen in the case where the elastic member is provided in the pedal connecting portion, and the reduction in transmission efficiency is largely suppressed. be able to.

[0010] Preferably, the first seal member and the support ring are slidable in the axial direction by the pressure of the pressure chamber,
The elastic member is brought into contact with a support ring as a movable member and a holding member as a fixed member. With this configuration, the elastic member is elastically deformed following the pressure fluctuation of the pressure chamber, and the volume of the pressure chamber can be easily changed repeatedly.

The elastic member is made of a disc spring or a synthetic rubber cylinder. This elastic member can secure a necessary amount of deformation and can reduce the storage space.

[0012] Preferably, the holding member is provided in the large diameter portion of the central bore of the housing and fixed to the housing, and has a plurality of spaced windows which are radially opened, and the claw portion of the guide sleeve is connected to the window. It is locked. This simplifies the mounting of the guide sleeve.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a master cylinder 1 is disposed between a clutch (or brake) pedal 2 and a clutch release cylinder (or brake cylinder) 3. The master cylinder 1 has a housing 10 having a central bore 6 having a large diameter portion 4 and a small diameter portion 5, and a pressure chamber 8 is formed in the central bore 6 by a piston 7 inserted into the central bore 6. The pressure chamber 8 can freely communicate with the output port 9 and the reservoir port 12, and when the pedal 2 is depressed, the piston 7 slides to the left via the push rod 11 to increase the oil pressure in the pressure chamber. The pressurized oil is transmitted to the clutch release cylinder 3 to enable the clutch release.

A cylindrical holding member 13 is fixed to the large diameter portion 4 of the central bore 6. The holding member 13 is a stationary member on the housing 10 side. The guide sleeve 14 which surrounds the piston 7 has a flange portion 15 and a plurality of claw portions 16 at its tip. The guide sleeve 14 is supported by the holding member 13 by engaging the claw 16 with the window 17 of the holding member 13.

The inner wall surface of the pressure chamber 8 of the central bore 6 has four tapered cut surfaces 18 in the illustrated example, and the cuts are made larger at the reservoir port 12 side. This is effective for securing an oil passage between the reservoir port 12 and the pressure chamber 8. A counterbore is formed at the tip of the piston 7 and a small-diameter hole 19 is formed.

A first seal member 20 slidably contacting the outer peripheral surface of the piston 7, facing the step portion of the small diameter portion 5 and facing the cut surface 18 is provided. First to prevent the escape of the pressure in the pressure chamber 8
The support ring 21 is attached to the back of the seal member 20. As shown in FIG. 2, the support ring 21 has a step portion 22 between the large diameter portion and the small diameter portion, and further has a plurality of slits 23 for securing an oil passage. The second seal member 24 is arranged so as to contact the flange portion 15 of the guide sleeve 14. The second seal member 24 is in sliding contact with the outer peripheral surface of the piston 7 and in close contact with the inner peripheral surface of the holding member 13 in a space between the reservoir port 12 and the opening side of the central bore 6, so that oil as a pressure medium is Prevent leakage to the outside.

A disc spring 25 as an elastic member is disposed between the support ring 21 and the holding member 13 so as to be located between the second seal member 24 and the support ring 21 in the axial direction. Support ring 2 for inner circumference of disc spring 25
The outer peripheral portion is brought into contact with the tip end surface of the holding member 13 as a stationary member. The disc spring 25 is connected to the pressure chamber 8.
Seal member 20 and support ring 2 according to the pressure of
1, the elasticity is selected so as to be elastically deformable so as to enable rightward sliding. Since the elastic force of the disc spring 25 is transmitted to the holding member 13, the holding member 13 is formed of a high-strength resin material, but the guide sleeve 14 which does not receive a high load is formed of a resin material having excellent slidability. .

FIG. 1 shows a non-operating state of the clutch pedal, that is, a state in which the clutch is completely engaged. In this piston position, at least one small-diameter hole 19 provided at a predetermined position of the piston 7 has a first hole. Is located on the housing opening side from the seal lip contact point of the seal member 20 with the piston 7, the pressure chamber 8 is in communication with the reservoir port 12 and is in a non-pressure state. When the piston 7 moves toward the pressure chamber 8 by operating the clutch pedal 2, the small-diameter hole 19 of the piston passes through the lip of the first seal member 20, the pressure chamber 8 becomes a closed chamber, and the pressure is increased, and the pressure of the clutch is increased. A disconnection operation is performed. When hydraulic pulsation due to engine vibration propagates from the clutch operating cylinder side (not shown) to the pressure chamber 8 through the output port 9, the piston 7 slightly vibrates in accordance with this pressure fluctuation, and is applied to the clutch pedal 2 via the push rod 11. In this case, the support ring 21 is set so as to be slidable in the axial direction in response to a change in the oil pressure in the pressure chamber 8. Then, by bending the disc spring 25, the volume in the pressure chamber 8 is changed, and the hydraulic vibration propagating to the piston 7 can be reduced.

When a coned disc spring is used as the elastic member, the disc spring has relatively high spring characteristics. In particular, the amount of displacement of the coned disc spring near the start of pressurization is small, and the small-diameter hole 9 passes through the seal lip of the first seal member 20 to increase the pressure. It has almost no effect on the stroke up to that point. It is also possible to change the characteristics of the disc spring in accordance with the frequency of the pulsation to be damped, and to arrange a plurality of disc springs in series and in parallel.

The example shown in FIG. 3 is different from the example shown in FIG. 1 mainly in the shape of the elastic member and the mounting of the guide sleeve, so that the second embodiment shown in FIG. An example will be described. The outer peripheral surface of the distal end of the guide sleeve 14 is welded to the large diameter portion of the central bore 6 of the housing 10 to make the guide sleeve 14 a stationary member. A second seal member 24 is disposed at a large diameter portion on the inner peripheral side of the distal end of the guide sleeve 14. The second seal member 24 slides on the outer peripheral surface of the piston 7 to prevent oil from leaking to the outside. The annular contact member 26 is fixed to the tip of the guide sleeve 14. The contact member 26 has a plurality of radially extending slits 27 so that the oil in the reservoir port 12 can reach the second seal member 24. The support ring 28 faces the contact member 26.
Distribute. The support ring 28 supports the first seal member 20 and is slidable in the axial direction together with the first seal member 20.

A cylindrical body 29 of an elastic member as a rubber cushion is disposed between the support ring 28 and the contact member 26. Preferably, the convex portions on both sides of the cylindrical body 29 are fitted into the concave portions of the support ring 28 and the contact member 26, and the cylindrical body 2
9 is supported by the support ring 28 and the contact member 26. Even if the cylindrical body 29 is bent by the support ring 28 between the cylindrical body 29 made of an elastic member such as synthetic rubber and the outer peripheral surface of the piston 7 and the inner peripheral surface of the central bore 6 of the housing 10, The clearance is set so that the cylindrical body 29 does not contact the housing 10 and / or the piston 7.

When the cylindrical member 29 made of a rubber cushion is used as the elastic member, the spring constant is lower than that of the disk spring 25 shown in the embodiment of FIG. On the other hand, the amount of deflection due to an increase in the internal pressure of the pressure chamber 8 increases, the loss stroke increases, and the deflection occurs even at low pressure. The pressure rise may become unstable at the pressure increase start point. Therefore, when an elastic member having a relatively low spring constant is used, the support ring 2 is used.
8 is brought into contact with the shoulder of the housing 10 in advance, and the guide sleeve 14 is fixed to the housing 10 in a state where a pre-compression load is applied to the cylindrical body 29 as an elastic member. In the example of FIG. 3, it is possible to restrict the axial movement to reduce the loss stroke and to solve the instability of the pressure rising point.

A plurality of spaced apart cuts 30 in the radial direction of the support ring 28 are used to force the oil in the reservoir tank to fill the oil passages of the clutch system and the brake system when the master cylinder is mounted on the vehicle. The oil that has passed through the cut 30 is supplied to the pressure chamber 8 while deforming the lip of the first seal member 20, and fills the pressure chamber 8 and the oil passage communicating with the pressure chamber 8 with oil. .

In the example of FIG. 3, as in the example of FIG.
When hydraulic pulsation due to engine vibration propagates from the clutch operating cylinder side (not shown) to the pressure chamber 8 through the output port, the piston 7 slightly vibrates in accordance with this pressure fluctuation and is transmitted to the clutch pedal (not shown) via the push rod 11. , Causing the pedal to vibrate and give the driver discomfort. However, in the example of FIG. 3, the support ring 28 is set so as to be slidable in the axial direction in accordance with the fluctuation of the oil pressure in the pressure chamber 8, and the cylindrical body 29 of the elastic member is bent so that the pressure in the pressure chamber 8 is reduced. Is changed to reduce the hydraulic pulsation propagating to the piston 7.

As described above, an example in which a cylindrical body as a disc spring and a rubber cushion is used as the elastic member has been described.
In addition, any elastic member for the purpose of damping vibration, such as a coil spring or a wave washer, can be used, and the present invention intends.

[Brief description of the drawings]

FIG. 1 is a sectional view of a master cylinder according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a support ring.

FIG. 3 is a sectional view of a master cylinder according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 master cylinder 6 central bore 7 piston 8 pressure chamber 9 output port 10 housing 12 reservoir port 13 holding member 14 guide sleeve 20, 24 sealing member 21, 28 support ring 25, 29 elastic member 26 contact member

Claims (8)

[Claims] A housing having an output port, a reservoir port, and a central bore; a piston for receiving a pedal depressing force so as to be axially slidable in the central bore and forming a pressure chamber in the central bore; A first seal member disposed in a space between the reservoir port and slidingly in contact with the outer peripheral surface of the piston; and a second seal member disposed in a space between the reservoir port and the opening side of the central bore and sliding in contact with the outer peripheral surface of the piston. A master cylinder for a vehicle, comprising: a seal member; a support ring disposed between the seal members and supporting the first seal member; and a guide sleeve fixed to the housing and surrounding the piston. And an elastic member disposed between the first seal member and the support ring in the axial direction according to the pressure pulsation of the pressure chamber. A master cylinder for a vehicle, wherein the master cylinder is elastically deformed so as to allow the pressure, and changes the volume of the pressure chamber. 2. The first seal member and the support ring are slidable in the axial direction by the pressure of the pressure chamber, and the elastic member abuts on a holding member that holds the support ring and the guide sleeve in the housing. Vehicle master cylinder. 3. The master cylinder for a vehicle according to claim 2, wherein the elastic member is a disc spring, and an inner peripheral portion thereof abuts on the support ring. 4. The master cylinder according to claim 3, wherein the support ring comprises a large diameter portion and a stepped small diameter portion, and an inner peripheral portion of the disc spring contacts the small diameter portion. 5. A holding member arranged in a large-diameter portion of a central bore of the housing and fixed to the housing and having a plurality of spaced-apart windows opened radially, and a claw portion of a guide sleeve is engaged with the window. The vehicle master cylinder according to any one of claims 1 to 4, wherein the vehicle master cylinder is stopped. 6. The first seal member and the support ring are slidable in the axial direction by the pressure of the pressure chamber, and the elastic member contacts the support ring and the guide sleeve or the contact member held by the guide sleeve. Item 4. A vehicle master cylinder according to Item 1. 7. The vehicle master cylinder according to claim 6, wherein the guide sleeve is fixed to the housing at the large diameter portion of the central bore, and the contact member faces the support ring. 8. The vehicle master cylinder according to claim 7, wherein the elastic member is a cylindrical body made of synthetic rubber, and receives a compressive load in the axial direction by sliding the support ring in the axial direction.