JP2543875Y2 - Master cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a master cylinder used for a hydraulic brake device and a hydraulic clutch device for a vehicle, and particularly, communication between a pressure chamber and a reservoir. The present invention relates to a so-called portless type master cylinder provided with a valve mechanism for intermittently connecting a valve.

(Conventional technology) Conventionally, this type of master cylinder has been
There is one shown in Japanese Patent Publication No.

The master cylinder has a step in which one end is detachably engaged with a holder fixedly provided in the inner hole of the cylinder body, and the other end is formed in the piston with the pressure chamber side having a large diameter. A rod movably housed in the large-diameter portion of the internal bore, a valve body fitted to the other end of the rod and capable of seating on a valve seat formed in a step portion of the stepped internal hole; A retainer that engages with the annular groove formed on the outer periphery, is assembled to the piston, and abuts the other end of the rod to regulate the movement of the rod to a predetermined amount; and the other end of the retainer and the rod. And a spring configured to bias the rod in a direction in which the valve element is seated on the valve seat. The retainer is formed on the outer periphery of the piston. Engage with annular groove to piston By attaching seen, from the piston rod and the spring and the retainer is prevented from falling to separate during with the set.

(Problems to be Solved by the Invention) However, in the valve mechanism of the conventional master cylinder described above, a retainer is crimped into an annular groove formed on the outer periphery of the piston located in the pressure chamber, and is assembled to the piston. Therefore, the piston inevitably has a cylindrical portion projecting toward the pressure chamber from the outer peripheral portion of the piston in which the piston cup forming the pressure chamber is fitted. Therefore, there is a problem that the axial length of the piston becomes unnecessarily large and the axial length of the master cylinder increases in order to obtain a predetermined stroke.

In view of the above, an object of the present invention is to shorten the shaft length of the master cylinder.

[Structure of device]

(Means for Solving the Problem) The technical means taken to solve the above-mentioned technical problem is that in the master cylinder, a piston cup forming the pressure chamber in the piston cup is fitted to an outer periphery. The axial length of the pressure chamber side end of the piston is equal to the axial length of the piston cup, and the valve mechanism can be disengaged from a holder provided at one end thereof in the bore of the cylinder body. And a rod whose other end is movably received in a large-diameter portion of a stepped bore formed in the piston with the pressure chamber side having a large diameter, and fitted to the other end of the rod. A valve body which can be seated on a valve seat formed at a step portion of the stepped inner hole; and a resiliently engages a groove formed inside the large diameter portion of the stepped inner hole and located inside the piston cup. Large diameter inner hole with step A projection having a concave cross-section inserted into the portion, and a spring seat extending from the projection along a surface exposed to the pressure chamber of the piston and locking one end of the return spring; A retainer for assembling and abutting against the other end of the rod to restrict the amount of movement of the rod to a predetermined amount; and a valve body interposed between the retainer and the other end of the rod so that the valve body is connected to the valve seat. And a spring for urging the rod in a direction to be seated.

(Operation) According to the above-described means, the axial length of the piston-side end portion of the piston in which the piston cup forming the pressure chamber in the piston cup is fitted to the outer periphery is equal to the axial length of the piston cup. Equally, a retainer for restricting the movement amount of the rod (valve element) to a predetermined amount is provided by inserting the protrusion with a concave cross section of the retainer into the large diameter portion of the stepped inner hole of the piston and providing the retainer with the protrusion. The engaging claw is resiliently engaged with a groove formed inside the large diameter portion of the stepped inner hole due to its elastic force and formed inside the piston cup forming a pressure chamber, and is assembled to the piston. Therefore, it is not necessary to provide the piston with a cylindrical portion projecting more toward the pressure chamber than the outer peripheral portion of the piston in which the piston cup forming the pressure chamber is fitted as in the related art. Thus, the piston can be shortened, and the axial length of the master cylinder can be shortened.

(Embodiment) An embodiment of a master cylinder according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a tandem master cylinder of a vehicle hydraulic brake system embodying the present invention. The master cylinder 10 has a conventional type and a portless type internal structure. It comprises a primary piston 12, a secondary piston 13, a pair of return springs 14, 15 and a valve mechanism V.

The cylinder body 11 is formed in a cylindrical shape having one end opened and stores the working fluid therein. Each of the pistons 12 and 13 and each of the return springs 14 and 15 are stored in an inner hole 11a thereof.

The primary piston 12 is slidably fitted in the inner hole 11a in a liquid-tight manner in the axial direction through piston cups 16a and 16b fitted on the outer periphery of both ends. The secondary piston 13 has piston cups 17a fitted at three locations on its outer periphery.
It is slidably fitted in the inner hole 11a in a liquid-tight manner in the axial direction via 17b and 17c. Return springs 16 and 17 are interposed between the pistons 12 and 13 and between the secondary piston 13 and the bottom of the inner hole 11a.
Is urged rightward in the figure by the return spring 14
The one end is locked to a snap ring 18 fitted in the open end of the opening 11a to be held at the non-operating position in the drawing, and the secondary piston 13 is moved rightward in the drawing by a return spring 15 having a slightly larger spring force than the return spring 14. And is screwed and fixed to the cylinder body 11 so that the inner hole 11a
The holder 20 of the valve mechanism V, which will be described later, is held at a non-operating position by being locked to the head of a stopper bolt 19 projecting inward. This allows the primary piston
Reference numeral 12 denotes the inside of the bore 11a of the cylinder body 11 and the cylinder body 1
A primary supply chamber R1 which is always in communication with the reservoir R through a supply port 11b formed in 1 and a reservoir R which is in communication with the reservoir R through a compensating port 11c formed in the cylinder body 11 and is always in communication with the hydraulic line through an outlet port 11d. It is partitioned into a primary pressure chamber R2 that communicates with it. The secondary piston 13 communicates with the secondary supply chamber R3 which always communicates with the reservoir R through a supply port 11e formed in the cylinder body 11 through the inner hole 11a, and communicates with the secondary supply chamber R3 via the valve mechanism V and outlets. It is partitioned into a secondary pressure chamber R4 which is always in communication with the hydraulic line through the port 11f.

Secondary piston 13 has piston cups 17a, 17b, 17
Piston cup 1 forming secondary pressure chamber R4 within c
The axial length of the secondary pressure chamber R4 side end of the secondary piston 13 in which the outer circumference 7a is fitted is equal to the axial length of the piston cup 17a, and the stepped opening that opens to the secondary pressure chamber R4 side is provided. A valve body 25 and a spring 26 of a valve mechanism V described later are interposed in the large diameter portion 13a of the stepped inner hole. The small-diameter portion 13b of the stepped inner hole functions as a throttle hole for liquid flow between the secondary supply chamber R3 and the secondary pressure chamber R4, and the end of the small-diameter portion 13b penetrates the secondary piston 13 in the radial direction, and Both ends are secondary supply rooms
The through hole 13c opens to R3. The stepped inner hole and the through-hole 13c constitute the communication hole of the present invention.

As shown in FIGS. 1 and 2, the valve mechanism V includes a retainer 23 fixed in the large-diameter portion 13a of the stepped inner hole of the secondary piston 13, and assembled to the secondary piston 13 by the retainer 23. Connected Groove 24,
A valve element 25 fitted to the right end of the connector groove 24
The connector glove 24 is interposed between the connector glove 24 and the retainer 23 so that the valve body 25 is seated on the valve seat 13e formed in the step portion of the stepped inner hole of the secondary piston 13. It is constituted by a spring 26 biasing rightward.

The retainer 23 is inserted into the large-diameter portion 13a of the stepped inner hole of the secondary piston 13 and formed on the inner periphery of the large-diameter portion 13a to resiliently engage with the annular groove 13d located inside the piston cup 17a. A cross-section having a plurality of locking claws 23a to be fitted is a concave portion 23b having a concave protruding portion, and a return spring 15 extending from the concave portion 23b along a surface exposed to the secondary pressure chamber R4 of the secondary piston 13. Spring seat 23 that locks one end
and c. The retainer 23 is made of spring steel, and the engaging claw 23a is snap-fitted into the annular groove 13d by its elastic force. The spring seat 23c of the retainer 23 has a piston cup 17a fitted to an outer periphery of an end of the secondary piston 13 on the side of the secondary pressure chamber R4.
Side, and prevents the piston cup 17a from falling off.

The connect glove 24 is accommodated in the large diameter portion 13a of the stepped inner hole of the secondary piston 13 so as to be able to move axially in the enlarged diameter portion 24a at the right end in the figure, and is prevented from falling off by the concave portion 23b of the retainer 23. Further, it is detachably engaged with a holder 20 fixed to a bottom surface of the inner hole 11a of the cylinder body 11 by a stopper bolt 19 at a locking portion 24b at the left end in the figure.

In such a valve mechanism V, the secondary piston
When the switch 13 is in the non-operation position shown in FIG.
When the secondary piston 13 moves a predetermined amount or more from the non-operating position shown in FIG. 1, the locking portion 24 b of the connecting glove 24 is separated from the holder 20, and the valve body 25 is acted upon by the spring 26. Is seated on the valve seat 13e.

 The operation of the present embodiment having the above configuration will be described.

When the primary piston 12 is pushed leftward in the figure by a push rod (not shown) at the time of depressing the brake pedal, the piston cup 16a passes through the compensating port 11c, and the reservoir R and the primary pressure chamber R2 are pressed.
Communication between them is interrupted. As a result, the hydraulic pressure in the primary piston pressure chamber R2 is increased, and the hydraulic pressure is applied to a hydraulic pipe (not shown) via the outlet port 11d. At the same time, when the secondary piston 13 is pushed leftward in the figure and the secondary piston 13 is pushed a predetermined amount or more,
The locking portion 24b of the connecting glove 24 is detached from the holder 20, the valve body 25 is seated on the valve seat 13e by the action of the spring 26, and the communication between the secondary supply chamber R3 and the secondary pressure chamber R4 is cut off. . As a result, the hydraulic pressure in the secondary pressure chamber R4 is increased, and the hydraulic pressure is applied to a hydraulic pipe (not shown) via the outlet port 11f. At this time, the hydraulic fluid in the primary pressure chamber R2 is supplied to the compensating port 11
Since the communication with the reservoir R is restricted by c, the escape of the hydraulic fluid from the pressure chamber R2 to the reservoir R is suppressed even before the piston cup 16a passes, so that the pressure chamber
The hydraulic pressure in R2 rises quickly to improve the braking effect, and the hydraulic fluid in the secondary pressure chamber R4 is supplied to the secondary supply chamber R3 by the small diameter portion 13b of the stepped inner hole that functions as a throttle hole.
Communication between the pressure chamber R4 and the secondary supply chamber R3 even before the valve body 25 is seated on the valve seat 13e.
As a result, the hydraulic pressure in the pressure chamber R4 rises quickly, and the effectiveness of the brake is improved.

When the depressing operation of the brake pedal is released, the operation is returned to the inoperative position shown in FIG. 1 by the action of the return springs 14, 15, and the supply chambers R1, R3 communicate with the pressure chambers R2, R4, respectively. . At this time, when a negative pressure is generated in each of the pressure chambers R2, R4 due to the line resistance of the hydraulic line, the piston caps 16a, 17 are provided through small holes provided in the lands of the pistons 12, 13.
From the back of a, the hydraulic fluid in each supply chamber R1 and R3 is filled with each pressure chamber R
2, It is sucked into R4 and flows.

Further, in the present embodiment, the piston cups 17a, 17
b, the axial length of the end of the secondary piston 13 on the side of the secondary pressure chamber R4 of the secondary piston 13 into which the piston cup 17a forming the secondary pressure chamber R4 is fitted is the piston cup.
The retainer 23 of the valve mechanism V is formed on the inner periphery of the large-diameter portion 13a by inserting the concave portion 23b into the large-diameter portion 13a of the stepped inner hole of the secondary piston 13. Annular groove 13d located inside piston cup 17a
A plurality of locking claws 23a formed on the outer circumference of the concave portion 23b are resiliently engaged with the secondary piston 13. Therefore, in a conventional master cylinder in which a retainer is crimped into an annular groove formed on the outer periphery of a piston located in a pressure chamber and is assembled to the piston, a pressure chamber is formed for assembling the retainer. Although a cylindrical portion that protrudes toward the pressure chamber from the outer peripheral portion of the piston where the piston cup is fitted is provided on the piston, the axial length of the piston and the axial length of the master cylinder are increased, but in this embodiment, There is no need to provide the secondary piston 13 with a cylindrical portion projecting more toward the secondary pressure chamber R4 than the piston cup 17a, so that the axial length of the secondary piston 13 can be reduced, and the axial length of the master cylinder can be reduced. Further, since it is not necessary to provide the above-described cylindrical portion, the valve length can be increased without increasing the shaft length of the large-diameter portion 13a of the stepped inner hole of the secondary piston 13 so as to deteriorate the workability and the inspection work of the valve seat 13e. By moving the seat 13e to the secondary supply chamber R3 side, the axial length of the small diameter portion 13b functioning as a throttle hole can be shortened, and the occurrence of clogging of foreign matter in the small diameter portion 13b can be suppressed, and the small diameter portion 13b can be suppressed. Can be improved in workability. Further, the retainer 23 is formed of spring steel, and the engaging claw 23a is snap-fitted into the annular groove 13d by its elastic force, so that the assembling property is good.

[Effect of the invention]

As described above, according to the present invention, the axial length of the pressure chamber side end of the piston in which the piston cup forming the pressure chamber is fitted on the outer periphery of the piston cup is set in the axial direction of the piston cup. A retainer that is equivalent to the length and regulates the movement amount of the rod to a predetermined amount is provided at the protrusion of the retainer by inserting a protrusion with a concave cross section of the retainer into the large diameter portion of the stepped bore of the piston. The locking claw is formed on the inner periphery of the large-diameter portion of the stepped inner hole by its elastic force and resiliently engages with the groove located inside the piston cup forming the pressure chamber, and is assembled to the piston. Therefore, it is not necessary to provide the piston with a cylindrical part projecting more toward the pressure chamber than the outer peripheral part where the piston cup forming the pressure chamber is fitted, as in the prior art. Cylinder axial length Without incurring a large, it is possible to obtain a predetermined pedal stroke. Further, since the retainer is made of spring steel, the assemblability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a master cylinder according to the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. 10… Master cylinder, 11… Cylinder body, 11a…
... Inner bore, 12 ... Primary piston, 13 ... Secondary piston, 13a ... Large diameter portion, 13b ... Small diameter portion, 13c ... Through hole, 13d ... Circular groove, 13e ... Valve seat, 14, 15 …… Return spring, 16a, 16b, 17a, 17b, 17c …… Piston cap, 19 …… Site bolt, 20 …… Honda, 23 …… Retainer, 23a …… Locking claw, 23b …… Recessed state, 23c …… Spring seat, 24 ... Connected glove, 24a ... Expanded portion (the other end), 24b ... Locking portion, 25 ... Valve, 26 ... Spring, V ... Valve mechanism, R ... Reservoir, R1 ... Primary supply chamber, R2 ... Primary pressure chamber, R3 ... Secondary supply chamber, R4 ... Secondary pressure chamber.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideaki Iijima 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Haruo Arakawa 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Examiner Satoru Ichinose, Inc. (56) References JP-A-59-96045 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A pressure which is slidably fitted in a fluid-tight and axial direction through a piston cup into an inner hole of a cylinder body for containing a hydraulic fluid and which is always in communication with a hydraulic line in the inner hole. A piston having a communication hole that forms a supply chamber that is always in communication with the chamber and the reservoir and communicates the pressure chamber with the supply chamber; and a piston that is housed in the pressure chamber and biases the piston toward a non-operation position. A return spring, which is mounted on the pressure chamber side end of the piston and opens the communication hole when the piston is in a non-operating position, and shields the communication hole when the piston is in an operating position, and A master cylinder having a valve mechanism for generating a hydraulic pressure in the chamber, wherein the pressure of the piston is fixed to an outer periphery of a piston cup forming the pressure chamber in the piston cup. The axial length of the side end is made equal to the axial length of the piston cup, and one end of the valve mechanism is detachably engaged with a holder provided in an inner hole of the cylinder body. A rod whose end is movably housed in a large-diameter portion of a stepped inner hole formed in the piston with the pressure chamber side larger in diameter; and a step fitted into the other end of the rod and having a step of the stepped inner hole. A valve body which can be seated on a valve seat formed in the above, and a locking claw which is formed on the inner periphery of the large diameter portion of the stepped inner hole and is resiliently engaged with a groove located inside the piston cup. A projection having a concave cross section inserted into the large-diameter portion of the stepped inner hole, and a spring extending from the projection along a surface exposed to the pressure chamber of the piston and locking one end of the return spring; And a seat, which is mounted on the piston and abuts on the other end of the rod. And a spring interposed between the retainer and the other end of the rod for urging the rod in a direction in which the valve body is seated on the valve seat. And a master cylinder comprising: