JPH0635069U - Master cylinder - Google Patents

Abstract

(57) [Abstract] [Object] The present invention prevents the radial movement and expansion of the end of the return spring that urges the piston toward the non-operating position, and prevents the inner wall of the cylinder hole from returning. An object of the present invention is to provide a master cylinder that is not damaged by the contact of the spring ends. A coil-shaped return spring 30 for urging the piston 4 toward a non-actuated position has its end portion 30A fitted to the outer periphery of the shaft portion 4B and projects radially outward from the shaft portion 4B. Cylinder hole 2 by abutting on flange 4C
In the master cylinder arranged inside, the diameter of the end portion 30A of the return spring 30 is set to a size that allows light press-fitting into the outer circumference of the shaft portion 4B and is adjacent to the flange 4C on the outer circumference of the shaft portion 4B. An annular groove 33 into which only the end turn 30a of the end portion 30A of the return spring 30 is fitted is formed in the portion.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a master cylinder for a brake or a clutch, for example.

[0002]

[Prior art]

 An example of this type of master cylinder is disclosed in Japanese Utility Model Laid-Open No. 3-44074. This is because a coiled return spring that urges the piston toward the non-actuated position fits its end on the outer circumference of the shaft and abuts the flange that projects radially outward from the shaft. And is arranged in the cylinder hole.

[0003]

[Problems to be solved by the device]

 In this conventional master cylinder, if the inner diameter of the end of the return spring that urges the piston toward the non-operating position is larger than the outer diameter of the shaft of the piston, the return spring will move due to movement of the piston. When a pressing force is applied to, the pressing force acts to expand the end coil of the end of the return spring that is in contact with the flange, and the smaller the spring constant of the return spring, the more the end coil will be wound. The phenomenon that the diameter is expanded to occurs. When the diameter of the end turn is increased, the end turn approaches the inner wall of the cylinder hole, and in the worst case, the inner wall of the cylinder hole is damaged due to contact, which causes a problem such as liquid leakage.

The present invention has been made in order to solve this problem, and prevents the return spring end from moving in the radial direction and expanding the diameter, so that the inner wall of the cylinder hole contacts the return spring end. The purpose is to provide a master cylinder that is not damaged by.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the master cylinder of the present invention has a coiled return spring that biases a piston toward a non-actuated position, with its end fitted to the outer circumference of the shaft and In the master cylinder that is placed in the cylinder bore by abutting on the flange that projects radially outward from the end, the end diameter of the return spring is set to a size that can be lightly pressed into the outer circumference of the shaft. Further, an annular groove into which only the end turn of the end portion of the return spring fits is formed in a portion of the outer periphery of the shaft portion adjacent to the flange.

[0006]

[Action]

 In the master cylinder of the present invention described above, the end diameter of the return spring is set to a size capable of being lightly press-fitted into the outer circumference of the shaft portion, and the annular groove formed in the portion of the outer circumference of the shaft portion adjacent to the flange is Since only the end turn of the return spring is fitted, the end of the return spring moves radially outward even if the pressing force of the piston movement acts on the return spring. It will not be expanded.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of a center valve type master cylinder embodying the present invention, in which a main portion is shown in cross section.

In FIG. 1, reference numeral 1 denotes a cylinder body, inside of which a cylinder hole 2 having a bottom 2 a with one end opened is formed, and two connection of a hydraulic fluid reservoir 50 is provided on an outer peripheral portion. Boss portions 3A and 3B respectively connected to the portions 51A and 51B are formed so as to project radially outward.

In the cylinder hole 2, a piston 4 is slidably accommodated on the bottom 2a side, and a head 4A equipped with a cap seal 5 defines a pressure chamber A with the bottom 2a. At the same time, a liquid replenishing chamber B communicating with the inside of the boss portion 3B through the through hole 15 is defined on the outer periphery of the piston 4 on the side opposite to the pressure chamber A. A shaft portion 4B protruding from the head portion 4A toward the bottom 2a side of the cylinder hole 2 is formed, and a protruding flange 4a is radially outwardly provided near the head portion 4A of the shaft portion 4B. .

The piston 4 has a long hole 6 that penetrates in the radial direction and extends in the axial direction, and this long hole 6 opens into the liquid replenishment chamber B. The piston 4 has a shaft portion 4B formed with a recess 7 having a predetermined depth which opens to the hydraulic chamber A, and the bottom 7a of the recess 7 has a valve hole 8 whose one end communicates with the elongated hole 6. Is open. A valve body 9 capable of closing one end of the valve hole 8 on the hydraulic chamber A side is housed in the recess 7, and a valve spring 11 received by a spring receiving plate 10 fitted in the recess 7 is long. It is biased toward the hole 6 side. From this valve body 9, a valve shaft 12 that extends loosely into the valve hole 8 and projects into the elongated hole 6 extends, and the end of the valve shaft 12 on the elongated hole 6 side penetrates through the elongated hole 6. It is in abutting engagement with a shaft-shaped valve opening member 13 that is locked to the hole wall of the cylinder hole 2.

Further, the piston 4 has a return spring 30 which is engaged in the hydraulic chamber A with one end engaged with the bottom 2 a of the cylinder hole 2 and the other end engaged with the flange 4 a of the piston 4. The hole 2 is biased to the side opposite to the bottom 2a. The piston 14 can be interlocked with another piston, which is slidably fitted to the opening side of the cylinder hole 2 and has the shaft portion 14 protruding to the outside of the cylinder body 1, through a known cage spring.

FIG. 2 shows a connecting structure of the return spring 30 and the piston 4, and this structure will be described in detail below with reference to FIG.

In FIG. 2 (A), the return spring 30 is a coiled spring in which a linear material having a predetermined wire diameter is continuously wound, and one end portion 30A thereof is viewed in the axial direction. The end turns 30a to 30d constituting the portion 30A are in close contact with each other and the other end has a narrow turn interval. Further, the return spring 30 has an inner diameter that can be lightly press-fitted into the outer diameter of the shaft portion 4B of the piston 4.

An annular groove 33 having the same width as the wire diameter of the return spring 30 is formed in the shaft portion 4A adjacent to the flange 4a of the piston 4 from the hydraulic chamber A side. This annular groove 33 has an inner diameter of the end turn 30a of the return spring 30 when the tip end turn 30a of the return spring 30 is fitted into the annular groove 33 through the shaft portion 4B of the piston 4 through the outer circumference. It has a depth dimension that does not restore or almost restores the original inner diameter (inner diameter in a free state before fitting to the outer circumference of the shaft portion 4B of the piston 4).

In such a configuration, the return spring 30 is fitted to the outer periphery of the shaft portion of the piston 4 by enlarging the inner diameter of the end portion 30A side to the outer diameter of the shaft portion 4B of the piston 4. Suru Thus, the end portion 30A side of the return spring 30 fitted to the outer periphery of the shaft portion 4B of the piston 4 tries to restore to the original inner diameter of the return spring 30, so that the shaft portion of the piston 4 is radially outward. 4A is elastically engaged with a pressing force, that is, in a state of light press-fitting without a radial gap between the return spring 30 and the shaft portion 4B of the piston 4, the outer periphery of the shaft portion 4B of the piston 4 Is fitted to.

When the return spring 30 is moved to the flange 4a side and the tip end coil 30a of the end portion 30A is fitted into the annular groove 33 in this light press-fit state, the tip coil end 30a is In order to restore the original inner diameter of the return spring 30, the diameter is reduced by twice the depth of the annular groove 33. Therefore, as shown in FIG. And the side surface 33b of the annular groove 33 on the flange 4a side. This completes the coupling of the return spring 30 to the shaft portion 4B of the piston 4.

In this way, the piston 4 to which the return spring 30 has been assembled and the valve body 9 and the valve spring 11 have been separately assembled is slidably inserted into the cylinder hole 2 and then, It is connected to the other piston which is slidably inserted into the opening side of the cylinder hole 2.

The master cylinder according to the embodiment of the present invention is configured as described above. Next, the operation of the master cylinder will be briefly described.

FIGS. 1 and 2 show the master cylinder when it is not in operation. The valve body 9 is separated from the bottom 7a of the recess 7, and the hydraulic fluid reservoir 50 is provided with a through hole 15-liquid replenishment. It communicates with the hydraulic chamber A through the chamber B, the elongated hole 6, the valve hole 8 and the recess 7.

When a brake pedal (not shown) is depressed in this state, the shaft portion 14 of the other piston moves to the bottom 2a side of the cylinder hole 2, and this movement is transferred to the piston 4 via the other piston. Transmitted. As a result, the piston 4 moves to the bottom 2a side of the cylinder hole 2 against the spring force of the return spring 30.

When the piston 4 is moved to the bottom 2 a side, the valve opening member 13 locked on the hole wall of the cylinder hole 2 does not move together with the piston 4, so that the valve opening member 13 is moved to the valve opening member 13 via the valve shaft 12. The engaged valve body 9 moves to the side of the elongated hole 8 with respect to the piston 4, and when the piston moves until the valve body 9 is seated on the bottom 7a of the recess 7 in engagement, the liquid The pressure chamber A is shut off from the hydraulic fluid reservoir 50. When the piston 4 is further moved to the bottom 2a side of the cylinder hole 2 together with the other piston, a hydraulic pressure is generated in the hydraulic chamber A, and this hydraulic pressure opens into the hydraulic chamber A (not shown). It is sent from the discharge port to the brake device. At this time, the hydraulic pressure is similarly sent from a hydraulic chamber (not shown) defined between the piston 4 and the other piston to a brake device (not shown).

When the piston 4 is moved to the bottom 2a side of the cylinder hole 2 during such operation and the return spring 30 is contracted, the end portion 30A pushes the flange 4a toward the bottom 2a side of the cylinder hole 2. Although a force (hereinafter, simply referred to as pressing force) is received, since there is a step in the radial direction between the tip end turn 30a engaged in the annular groove 33 and the end turn 30b adjacent to this end turn 30a. In the tip end coil 30a, a part of the pressing force by the end coil 30b is applied from the outside of the radius of the cylinder hole 2, that is, the tip coil 30a is urged to the bottom 33a of the annular groove 33. Since it receives such a force, the end portion 30A of the return spring 30 is elastically engaged with the shaft portion 4B of the piston 4 with a pressing force. The above pressure Even if the force acts on the return spring 30, the return spring 30 does not rattle in the radial direction.

According to such an embodiment, the diameter of the end portion 30A of the return spring 30 is set so that it can be lightly press-fitted into the outer periphery of the shaft portion 4C of the piston 4, and the return spring 30 Since only the tip end turn 30a of the end portion 30A of the return spring 30 is fitted in the annular groove 33 formed in the shaft portion 4C of the piston 4, the bottom 2a of the cylinder hole 2 of the piston 4 is Even if the pressing force due to the side movement acts on the return spring 30, the tip end coil 30a is urged to the bottom 33a of the annular groove 33 by the coil end 30b adjacent to the tip coil 30a. Therefore, the tip end turn 30a of the return spring 30 is prevented from expanding radially outward of the cylinder hole 2, and the end portion 30A of the return spring 30 taps in the radial direction. Will disappear.

In the illustrated embodiment, the return spring 30 is provided with the annular groove 33 in the shaft portion 4B of the piston 4 and is directly coupled to the shaft portion 4B. The proposal can be applied to a cup-type spring retainer with a flange arranged at the end of the piston 4 in the same manner as in the above embodiment.

Further, in the present invention, the shaft portion 4B to which the return spring 30 is fitted is prepared as a separate body from the piston 4, and the separate shaft portion is attached to the piston 4 to be integrated. It can also be applied to things.

Furthermore, the tip end of the shaft portion 4B of the piston 4 on the bottom 2a side of the cylinder hole 2 has a stepped shape with a slightly smaller diameter, and the return spring 30 has the shaft portion 4B of the piston 4 as in the above embodiment. May be combined with.

Further, the return spring provided not for the second piston of the tandem master cylinder like the piston 4 but for the brimary piston is connected to the shaft portion as in the above embodiment. Good.

[0029]

[Effect of device]

 As described in detail above, according to the master cylinder of the present invention, the end diameter of the return spring is set so that it can be lightly press-fitted into the outer periphery of the shaft portion, and the return spring is formed in the portion adjacent to the flange of the outer periphery of the shaft portion. Since only the end turn of the return spring is fitted in the annular groove, even if the pressing force due to the movement of the piston acts on the return spring, the end portion of the return spring is Is prevented from expanding radially outward, preventing contact with the inner peripheral surface of the cylinder hole, and achieving the intended function of the master cylinder, while also reducing the cylinder hole diameter. It can be made smaller and smaller.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view showing a master cylinder as an embodiment of the present invention.

FIG. 2 is an enlarged view of an essential part showing a connecting structure of a return spring and a piston in FIG.

[Explanation of symbols]

 2 Cylinder hole 4 Piston 4B Shaft part 4a Flange 30 Return spring 30A End part 30a-30e End turn 33 Annular groove

Claims (1)

[Scope of utility model registration request] 1. A coiled return spring for urging a piston toward a non-actuated position has an end portion fitted on an outer circumference of a shaft portion and a flange protruding radially outward from the shaft portion. In the master cylinder that is placed in contact with the cylinder hole, the end diameter of the return spring is
The size is set so that it can be lightly press-fitted to the outer periphery of the shaft portion, and the retarder is provided on a portion of the outer periphery of the shaft portion adjacent to the flange.
A master cylinder with an annular groove that fits only the end turn of the spring.