JPH067017Y2 - Master cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a master cylinder used in a brake system of an automobile, and more particularly to a tandem master cylinder equipped with a hydraulic control valve.

(Prior Art) Conventionally, a tandem type master cylinder used for a two-system brake of an automobile is known in which a sleeve for guiding a piston is provided inside a master cylinder body.

In this type of master cylinder, a primary piston and a secondary piston are arranged in a bottomed cylindrical master cylinder body, and a cylindrical sleeve is provided in a pressurizing chamber defined between the primary piston and the secondary piston. A flange extending radially outward on the rear end side of the secondary piston is slidably contacted with the inner circumference of the sleeve, and a spring member is provided in the gap between the secondary piston and the sleeve to move the secondary piston to the rear (primary side). It is biased to the piston side). The sleeve guides the movement of the secondary piston due to the increase or decrease of the hydraulic pressure in the pressurizing chamber. (For example, US Pat. No. 4,249,381 describes a master cylinder having a similar structure.) When the sleeve is provided in the master cylinder body so as to guide the movement of the secondary piston, the inner circumference of the master cylinder body is increased. Unlike the one in which the secondary piston is slid, it has the advantage that it is not necessary to machine the inner peripheral surface of the master cylinder body with high precision.

(Problems to be Solved by the Invention) However, the conventional master cylinder having a sleeve has the following problems.

Generally, when a vehicle is braked, a large amount of load is applied to the front wheels due to the movement of the center of gravity caused by the inertia of the vehicle body. Therefore, when the same braking force is applied, the rear wheels are braked before the front wheels and the posture of the vehicle becomes unstable. In order to prevent this, it is known that a hydraulic pressure control valve is provided at the discharge port of the master cylinder that supplies hydraulic pressure to the brake system on the rear wheel side.

However, in this case, when the brake system of the front wheels is damaged, the vehicle must be braked only by the braking force of the brake system of the rear wheels. At this time, the hydraulic control provided in the brake system of the rear wheels is required. If the valve operates, the braking force will be lost, and there is a drawback that the braking cannot be performed sufficiently.
Therefore, when the brake system of the front wheels is damaged, the secondary piston moves over a predetermined stroke, making use of the hydraulic control valve to engage one end with the valve body of the hydraulic control valve and the other end with the master. An engagement member that protrudes inside the cylinder is provided, and the secondary piston displaces the engagement member when the secondary piston strokes a predetermined amount or more, thereby restricting the valve operation of the valve element and not operating the hydraulic control valve. There is something.

However, with a master cylinder with a sleeve,
Since the sleeve separates the engagement member from the secondary piston, there is a problem that the operation of the hydraulic control valve cannot be regulated when the front wheel brake system is damaged.

The present invention has been made in view of the above problems,
The purpose thereof is to allow the operation of the hydraulic control valve to be restricted when the front wheel brake system is broken in the master cylinder having the sleeve.

(Means for Solving Problems) As means for solving the above problems and achieving the object, a sleeve is provided in the master cylinder body, and the primary piston and the secondary piston are slidably contacted with the sleeve. A master cylinder in which the sleeve holds a seal member so as to form a pressurizing chamber between the primary piston and the secondary piston, while guiding the movement of the primary piston and the secondary piston. A fluid pressure control valve is connected to the discharge port side, and one end of the fluid pressure control valve is engaged with the valve body of the fluid pressure control valve and the other end is projected to the outer peripheral portion of the sleeve inside the master cylinder body. An engaging member is provided, an annular slider is slidably fitted on the sleeve, and a long hole extending in the axial direction is provided on the side wall of the sleeve. A connecting member that is inserted into the elongated hole and connects the secondary piston and the slider is provided, and the slider connected to the secondary piston displaces the engaging member when the secondary piston moves by a predetermined stroke or more and the liquid It is characterized in that the valve operation of the pressure control valve is regulated.

(Operation) With this configuration, when the brake system of the front wheel is damaged, the secondary piston moves by a predetermined stroke or more, and the annular slider connected to the secondary piston is attached to the outer peripheral portion of the sleeve inside the master cylinder body. It engages with the other end of the protruding engaging member and moves the engaging member to regulate the valve operation of the hydraulic control valve.

(Example) Next, the Example of this invention is described based on drawing. In this embodiment, a tandem master cylinder used for a two-system brake will be described.

First, a first embodiment will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a tandem master cylinder body having a cylindrical shape with a bottom. A primary piston 2 is provided on the opening side (rear side) of the master cylinder body 1 and a secondary piston 3 is provided on the bottom side (front side). It is provided. A first pressure chamber 4 is formed between the primary piston 2 and the secondary piston 3, and a second pressure chamber 5 is formed between the secondary piston 3 and the bottom of the master cylinder body 2. The first pressure chamber 4 communicates with the rear wheels of the two brake systems, and the second pressure chamber 5 communicates with the front brake system.

On the front end surface (the left end surface in the figure) of the primary piston 2,
The bolt 6 is stopped. The head portion of the bolt 6 is fitted into the cup portion 7 located on the rear side (right side in the figure) of the secondary piston 3, and the primary piston 2
A spring member 8 is interposed between the front end surface of the cup and the expanded base end of the cup portion 7.

A cylindrical sleeve 9 is provided along the inner circumference of the master cylinder body 1 of the first pressurizing chamber 4. The rear side of the secondary piston 3 is formed in a cup shape, and a flange 3a extending radially outward is formed at the tip thereof, and the flange 3a is slidably contacted with the inner circumference of the sleeve 9. There is.
The front side (the left end in the figure) of the secondary piston 3 is also formed in a cup shape, and a spring member 10 is interposed between the cup-shaped bottom portion 3b and the master cylinder body 1.

Liquid tightness of the first pressurizing chamber 4 and the second pressurizing chamber 5 is secured by the sealing materials 11 and 12 held on the inner surface of the master cylinder body 1, respectively. Then, the first pressurizing chamber 4 communicates with the inside of the reservoir tank 15 in which the oil liquid is stored, through a passage 13 formed in the master cylinder body 1 and a passage 14 formed along the seal material 11, The second pressurizing chamber 5 also communicates with the inside of the reservoir tank 15 via a passage 16 formed in the master cylinder body 1 and a passage 17 formed along the sealing material 12. Then, as the primary piston 2 and the secondary piston 3 move forward, the passages 14 and 17 are closed, and the hydraulic pressures in the first and second pressurizing chambers 4 and 5 rise.

The discharge port 18 of the first pressurizing chamber 4 has a hydraulic pressure control valve shown in FIG.
19 is connected, and explaining this hydraulic control valve 19,
Reference numeral 20 denotes a tubular housing, and an outer peripheral side of the housing 20 includes a reduced diameter portion 20a and an enlarged diameter portion 20b. The housing 20 has the reduced diameter portion 20a screwed onto the inner circumference of the discharge port. It is installed by A stepped hole 20c is formed on the inner peripheral side of the reduced diameter portion 20a. Further, the stepped hole 21a is formed on the inner circumference of the expanded diameter portion 20b.
A cylindrical adapter 21 having a threaded portion is screwed, a threaded portion 21b is formed in the stepped hole 21a, and the threaded portion 21b has a brake pipe (not shown) communicating with the rear wheel braking system. Mounted.

A flanged working piston 22 is slidably fitted into the stepped hole 21a of the adapter 21 and the stepped hole 20c of the reduced diameter portion 20a of the housing 20, and the working piston 22 is attached by a spring member 23 to the adapter 21. Biased to the side. A valve seat 22a is formed on the end surface of the working piston 22 on the master cylinder body 1 side, and the pressure receiving area of the end surface on the valve seat 22a side is the working piston 22.
Is set smaller than the pressure receiving area of the end surface of the adapter 21 side. A communication passage 22b is formed in the working piston 22, one end of the communication passage 22b opens from the valve seat 22a to the inside of the reduced diameter portion 20a, and the other end from the end surface of the working piston 22 on the adapter 21 side to the inside of the adapter 21. It is open to.

A valve body 24 is disposed inside the reduced diameter portion 20a of the housing 20. The valve body 24 has a disc shape, and a valve portion 24a corresponding to the valve seat 22a is formed at the center of one side surface of the valve body 24. On the other side surface of the valve body 24, a tubular portion 24b that coincides with the axis of the valve body 24 is formed. A peripheral edge portion on one side surface of the valve element 24 is biased by a spring member 25 so as to be able to be seated on and off the step portion. A through hole (not shown) is formed in the peripheral edge portion of the valve body 24, and when the peripheral edge portion of the valve body 24 is seated on the step portion, the stepped hole 20c of the reduced diameter portion 20a is passed through the through hole. Communicate with each other.

The tip of the reduced diameter portion 20a of the housing 20 and the master cylinder body 1
An engaging member 26 is arranged between the and. The engaging member 26 is composed of a disc portion 26a and a pair of shaft portions 26b and 26c projectingly provided on both side surfaces of the disc portion 26a, and one shaft portion 26b is a tubular portion of the valve body 24. The other shaft portion 26c, which faces the inside of 24b, projects into the gap between the inner circumference of the master cylinder body 1 and the outer circumference of the sleeve 9, as shown in FIG.

The sleeve 9 provided in the first pressurizing chamber 4 is provided with an axially long hole 9a as shown in FIG. An annular slider 28 shown in FIG. 5 is slidably fitted on the outer periphery of the sleeve 9, and a protrusion 28a penetrating the elongated hole 9a of the sleeve 9 is formed on the inner periphery of the slider 28. Has been done. The protrusion 28a is held by the flange 3a of the secondary piston 3 and the ring 29 fixedly fitted to the outer periphery of the secondary piston 3, and the slider 28 and the secondary piston 3 are connected by the protrusion 28a as a connecting member. As a result, it has an integrated structure when assembled.

The operation of the above configuration will be described.

First, in normal operation of the master cylinder, when the brake pedal is depressed and the primary piston 2 is pushed to the secondary piston 3 side via a push rod (not shown),
The pressurizing chamber 4 and the second pressurizing chamber 5 are pressurized to generate the same hydraulic pressure.

In the initial stage, the valve seat 22a of the working piston 22 has the spring member 2
It is separated from the valve element 24 by the urging force of 3, and the first pressurizing chamber and the rear wheel brake system are in communication. When the hydraulic pressure in the first pressurizing chamber 4 rises, the pushing force of the working piston 22 overcomes the spring member 23 and the valve seat 22a of the working piston 22.
The valve body 24 will be seated on. Then, after this, as the working piston 22 reciprocates in the opening / closing direction in response to the increase in hydraulic pressure, the valve body 24 repeatedly moves to and from the valve seat 22a, and the hydraulic pressure supplied to the rear wheel brake system is increased. Becomes slow.

Next, a case where the brake system of the front wheels is damaged will be described.

When the brake system of the front wheels is damaged, the hydraulic pressure in the second pressurizing chamber 5 decreases. Therefore, when the brake pedal is depressed and the primary piston 2 is pushed through a push rod (not shown), the primary piston 2 and the secondary piston 3 are separated from each other. It moves forward more than a predetermined stroke in a normal state against the biasing force of the spring member 10. Along with that, the slider 28 connected to the secondary piston 3 and fitted on the sleeve 9 moves in the gap between the inner circumference of the master cylinder body 1 and the outer circumference of the sleeve 9, so that the other side of the engaging member 26 is moved. The engaging member 26 slides in the moving direction of the secondary piston 3 by engaging with the shaft portion 26c of the. As a result, one shaft portion 26b of the engaging member 26 is
Comes into contact with the cylindrical portion 24b of the valve body 24, the valve body 24 is rotated, and the valve seat 2
The operation of the valve element 24 is regulated by being held in a separated state from 2a.
Therefore, the first pressurizing chamber 4 and the rear wheel braking system are in communication with each other, and the hydraulic pressure generated in the first pressurizing chamber 4 is directly transmitted to the rear wheel braking system.

FIG. 6 and FIG. 7 show a second embodiment, which is different from the first embodiment only in the coupling means for connecting the secondary piston 3 and the slider 31. A radial hole 3c is formed on the outer circumference of the secondary piston 3, and one end of a pin 32 penetrating the elongated hole 9a of the sleeve 9 is fitted into the hole 3c. A radial hole 31a is also formed in the slider 31, and the other end of the pin 32 is fitted in the hole 31a. In this way, by using the pin 32 as the connecting member, the slider 31
And the secondary piston 3 are connected. The operation of the third embodiment is similar to that of the second embodiment, when the brake system of the front wheels is damaged, the slider 31 moves to engage with the other shaft portion 26c of the engaging member 26. The valve operation of the hydraulic control valve 19 is restricted.

With the constructions of the first and second embodiments, it is not necessary to position the elongated hole 9a in the circumferential direction when the sleeve 9 is assembled, and the workability of assembling is good.

(Effect of the Invention) As described in detail above, according to the present invention, the other end of the engaging member whose one end engages with the valve body of the hydraulic control valve is projected to the outer peripheral portion of the sleeve in the master cylinder body. , An annular slider slidably fitted on the sleeve and a secondary piston are connected by a connecting member inserted in a long hole of the sleeve,
Since the slider connected to the secondary piston displaces the engaging member to regulate the valve operation of the hydraulic control valve when the secondary piston moves by a predetermined stroke or more, it is a master cylinder having a sleeve. Even if the front wheel brake system is damaged, the valve operation of the hydraulic control valve can be regulated, and there is no need to position the elongated hole in the circumferential direction when the sleeve is assembled, resulting in excellent workability in assembly. .

[Brief description of drawings]

1 is a longitudinal sectional view showing a first embodiment of a master cylinder of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a master cylinder of FIG. FIG. 4 is an enlarged view of a main part, FIG. 4 is a perspective view of a sleeve of the first and second embodiments, FIG. 5 is a perspective view of a slider of the first embodiment, and FIG. 6 is a second embodiment. FIG. 7 is an enlarged view of a main part of an example, and FIG. 7 is a perspective view of a slider of the second embodiment. 1 ... Master cylinder body 2 ... Primary piston 3 ... Secondary piston 3a ... Flange 9 ... Sleeve 9a ... Slot 10 ... Spring member 19 ... Fluid pressure control valve 26 ... Engagement member

Claims (1)

[Scope of utility model registration request] 1. A master cylinder body is provided with a sleeve, and a primary piston and a secondary piston are provided around the sleeve to guide the movement of the primary piston and the secondary piston, and the primary piston and the secondary piston are provided. In a master cylinder in which the sleeve holds a seal member so as to form a pressurizing chamber between, a hydraulic pressure control valve is connected to the discharge port side of the pressurizing chamber, and one end is connected to the hydraulic pressure control valve. An engagement member is provided which is engaged with the valve body of the fluid pressure control valve and the other end of which is projected to the outer peripheral portion of the sleeve inside the master cylinder body, and an annular slider is slidably mounted on the sleeve. A coupling member that is fitted and has a long hole extending in the axial direction on the side wall of the sleeve, and that is inserted through the long hole and connects the secondary piston and the slider. A master, characterized in that a slider connected to the secondary piston displaces the engaging member to restrict valve operation of the hydraulic pressure control valve when the secondary piston moves more than a predetermined stroke. Cylinder.