JPH05238377A - Method and device for setting ineffective stroke of hydraulic master cylinder for vehicle - Google Patents

Abstract

PURPOSE:To high-precisely and easily provide a hydraulic master cylinder with an ineffective stroke by setting an ineffective stroke between a relief port and a primary cup. CONSTITUTION:Since a piston guide 9 is pressed further internally of a bearing hole 3a than a lock position by a lock nut 10, a distance L2 longer than length of a relief port 22 being fully closed by a primary cup 13, i.e., a distance L2 longer than an ineffective stroke L1 is set between a stepped part, 3c formed between a cylinder hole 3 and a bearing hole 3a and a piston guide 9 in a locked state. This constitution prevents the piston guide 9 from making contact with the stepped part 3c between the cylinder hole 3 and the bearing hole 3a and interference therewith until a relief port 22 is fully closed by the primary cup 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic master cylinder for hydraulically actuating brakes and clutches of various vehicles such as four-wheeled vehicles. To a method and apparatus for setting the invalid stroke up to the maximum as accurately as possible.

[0002]

2. Description of the Related Art As a hydraulic master cylinder for hydraulically operating a brake of an automobile, there is, for example, one disclosed in Japanese Utility Model Publication No. 1-43343.

This hydraulic master cylinder is a tandem type in which the rear shaft of the primary piston is housed inside a hydraulic booster to shorten the cylinder body length, and is annular in a large diameter bearing hole continuous with the cylinder hole. The piston guide is attached to the primary piston, and the primary piston is retained on the center axis of the cylinder hole by inserting the rear shaft through the annular piston guide that is installed in this bearing hole. Is regulated by contact with the piston guide.

A primary cup, which slides liquid-tightly in the cylinder bore, is mounted on the tip side of the primary piston, and when the primary piston is in the retracted limit,
An invalid stroke is set between the primary cup and the relief port.

[0005]

In such a structure, the rear end of the cylinder body in which the bearing hole is opened serves as a machining reference surface, and the cylinder hole and the bearing hole are formed with reference to the rear end of the body. However, when fixing the piston guide in place, in addition to the manufacturing error of the piston guide itself and the circlip that prevents it from coming off, the stepped portion between the cylinder hole and the bearing hole and the circlip are fitted. The above-mentioned invalid stroke may not be accurately set due to a number of manufacturing errors such as circumferential grooves that overlap.

The present invention has been made in view of the above circumstances, and an object thereof is to set an invalid stroke in which a predetermined invalid stroke can be accurately and easily obtained in a hydraulic master cylinder. And to provide the device.

[0007]

To achieve the above object, the method of the present invention is an annular piston guide in which a rear shaft of a piston inserted in a cylinder hole is mounted in a bearing hole continuous with the cylinder hole. A method for setting an ineffective stroke in a hydraulic master cylinder for a vehicle, in which the piston is biased toward the bearing hole to abut against the piston guide to regulate the retreat limit of the piston. In, while screwing the piston guide into the bearing hole, by screwing the piston guide, the piston is advanced to the bottom direction of the cylinder hole, in the primary cup fitted to the tip of the piston, After fully closing the relief port on the peripheral wall of the cylinder hole, rotate the piston guide in the reverse direction to set the retracted position of the piston guide to the lock nut In and fixed to, it is characterized by setting the ineffective stroke between the relief port and the primary cup.

In the device of the present invention, the rear shaft of the piston inserted in the cylinder hole is inserted into and held by an annular piston guide mounted in a bearing hole continuous with the cylinder hole. In a hydraulic master cylinder device for a vehicle in which a piston biased in the bearing hole direction is brought into contact with the piston to regulate a backward movement limit of the piston, the piston guide is attached to the bearing hole by screwing, While fixing the screwing position of the piston guide with a fixing means such as a lock nut, the primary cup fitted to the tip of the piston in the gap between the step portion of the cylinder hole and the bearing hole and the piston guide is The feature is that the length is set larger than the length until the relief port on the peripheral wall of the cylinder hole is fully closed.

[0009]

By setting a gap between the step portion between the bearing hole and the cylinder hole and the piston guide, the movement of the primary cup until the relief port is fully closed is allowed. The closure of the relief port by the primary cup is carried out by confirming the air blown from the relief port by using the air blow in the cylinder hole after the cutting work or by directly visually observing from the relief port side. The return amount of the piston guide from the cup closed state is calculated based on the pitch of the screw thread that is screwed into the bearing hole, and a predetermined invalid stroke is obtained by rotating it, for example, 1.5 rotations or 4 rotations. ..

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

A hydraulic master cylinder 1 has a cylinder hole 3 formed in a cylinder body 2 and a primary piston 4 in a cylinder hole 3.
And a secondary piston 5 are inserted in a liquid-tight and movable manner, and a first hydraulic chamber 6 and a second hydraulic chamber 7 are defined between the pistons 4, 5 and the cylinder hole 3 in a tandem type. so,
The rear end of the cylinder body 2 is attached to the front of the negative pressure booster 8 by screwing (not shown).

On the rear side of the cylinder body 2, a large-diameter bearing hole 3a continuous with the cylinder hole 3 is provided with an opening at the rear end face, and the bearing hole 3a has an annular piston guide 9 and A lock nut 10 is screwed on as a means for fixing this. The bearing hole 3a is formed deeper inside the locked piston guide 9 than the length including an ineffective stroke L1 described later. The primary piston 4 has a small-diameter rear shaft 4a inserted through the piston guide 9, is held on the cylinder center shaft, and further comes out of the rear seal member 11 and projects into the negative pressure booster 8 from the rear shaft 4a. The tip of a push rod 12 for pushing the primary and secondary pistons 4 and 5 toward the bottom of the cylinder hole 3 is inserted into the end.

A primary cup 13 is fitted to the tip of the primary piston 4, and a primary cup 14 and a secondary cup 15 are fitted to the tip and the rear end of the secondary piston 5, respectively. The pressure chamber 6 and the second hydraulic chamber 7 are liquid-tightly sealed. First hydraulic chamber 6
The primary return spring 16 is contracted,
Further, a secondary return spring 17 is contracted in the second hydraulic chamber 7 with a set load lower than that of the primary return spring 16, and both the primary and secondary pistons 4 and 5 have return springs 16 and 1.
The elastic force of 7 urges the bearing hole 3a toward the bearing hole 3a, and the retreat limit thereof is restricted by the contact between the step portion 4b of the primary piston 4 and the piston guide 9.

A reservoir 18 is attached to the mounting boss portion 2a protruding upward from the cylinder body 2 so that the working fluid stored therein is supplied to the cylinder hole 3 at any time. The inside of the mounting boss portion 2a is partitioned into two auxiliary liquid storage chambers 19 and 20 by a partition wall 2b. One of the auxiliary liquid storage chambers 19 has a cylinder hole 3 in which the first hydraulic chamber 6 is provided via a communication hole 21 formed in the ridge 2c of the cylinder body 2, a relief port 22 and a supply port 23. The other sub-liquid storage chamber 20 communicates with the rear side, and communicates with the front side of the cylinder hole 3 in which the second hydraulic chamber 7 is provided, via the relief port 24 and the supply port 25.

A secondary cup 26 and an O-ring 27 are fitted in the seal grooves 9a and 9b formed on the inner and outer circumferences of the piston guide 9, so that the space between the primary piston 4 and the bearing hole 3a is liquid-tight. It is sealed. The male screw 9c of the piston guide 9 is formed on the outer periphery of the rear portion, and is also formed on the rear portion side of the bearing hole 3a, and therefore is screwed into the screw 3b.
The rear end surface of the piston guide 9 is provided with a polyhedral tool hooking hole 9d as shown in FIG.
Is screwed into or unscrewed from the bearing hole 3a with a cylindrical turning tool (not shown) inserted into the tool hooking hole 9d.

Lubricating grooves 9e, 9e for connecting the front end face and the seal groove 9a are provided on the inner peripheral surface of the piston guide 9, and a part of the hydraulic fluid is introduced into the secundary cup 26. It prevents scratching and damage due to rubbing against the primary piston 4. The outer circumference of the tip of the piston guide 9 is
Even when the piston guide 9 is cut into the C surface and is screwed in until it comes into contact with the step portion 3c of the cylinder hole 3 and the bearing hole 3a, the piston guide 9 and the bearing hole 3a generate threads from the thread. A space for accumulating chips is ensured so that the primary piston 4 can smoothly slide together with the above-mentioned lubricating grooves 9e, 9e.

The lock nut 10 is a ring nut having a hollow portion having a diameter larger than the tool engaging hole 9d of the piston guide 9, and a tool engaging hole 10a having a diameter larger than the hollow portion is formed on the rear end surface thereof in a cylindrical shape. The lock nut 10 is recessed in a shape suitable for inserting and hooking the rotating tool, and the lock nut 10 can be rotated even when the rotating tool is inserted into the tool hooking hole 9d of the piston guide 9.

The retracting limit of the primary piston 4 and the secondary piston 5 when not in operation is regulated by the piston guide 9 as described above. , 14,
The distance until the relief ports 22 and 24 are fully closed, that is, the ineffective stroke is determined by the mounting position of the piston guide 9.

This will be described with reference to FIG. 1 which shows the relationship between the primary piston 4 and the piston guide 9 in an enlarged manner. The primary guide 4 is temporarily retracted by screwing the piston guide 9 screwed into the bearing hole 3a. Push it toward the inside of the cylinder hole 3 rather than the position. This pushing amount is
At the distance until the primary cup 13 at the tip completely closes the relief port 22 (the position indicated by an imaginary line in FIG. 1), the relief port 22 is closed by using, for example, air blow in the cylinder hole performed after cutting. , Confirm the cut of the air vacuumed from the relief port 22 or directly look through the opening of the relief port 22.

Next, when the piston guide 9 is rotated in the reverse direction from this cup closed state, the primary piston 4 is retracted by the elastic force of the return springs 16 and 17. The return amount of the piston guide 9 is calculated based on the pitch of the screw thread that is screwed into the bearing hole 3a, and is rotated by, for example, one rotation or 2.5 rotations, so that the primary cup 13 and the relief port 22 are separated. At the same time, a predetermined invalid stroke L1 is set, and at the same time, the retreat limit of the primary piston 4 is restricted. Then, the lock nut 10 is brought into contact with the piston guide 9 to fix the piston guide 9 (solid line state in FIG. 1).

In the above-described invalid stroke setting method, the piston guide 9 is pushed inward of the bearing hole 3a beyond the lock position of the lock nut 10, so that the step formed between the cylinder hole 3 and the bearing hole 3a. Between the portion 3c and the locked piston guide 9, a length until the primary cup 13 fully closes the relief port 22, that is, a distance L2 longer than the invalid stroke L1 is set. As a result, the piston guide 9 does not come into contact with and interfere with the stepped portion 3c of the cylinder hole 3 and the bearing hole 3a until the primary cup 13 completely closes the relief port 22. Further, when the invalid stroke L1 is set on the side of the primary piston 4 in this way, the backward limit of the secondary piston 5 connected with a predetermined gap is restricted, and at the same time, the predetermined invalid stroke is also set on the side of the secondary piston 5. Is set.

In this embodiment, since the invalid stroke L1 on the primary piston 4 side is set by screwing the piston guide 9 as described above, the circlip and the circumference which have been a cause of the invalid stroke setting failure. Since the groove can be eliminated and the manufacturing error of the piston guide 9 itself does not pose a problem, the invalid stroke L1 can be set more accurately and easily than the conventional one.

Further, the gap L2 between the step portion 3c between the cylinder hole 3 and the bearing hole 3a and the piston guide 9 is set larger than the length until the primary cup 13 completely closes the relief port 22, The setting of the invalid stroke by the method of the present embodiment is not hindered. Further, since the invalid stroke on the secondary piston 5 side is also set in association with the primary piston 4 side, higher accuracy than before can be obtained.

Although the tandem type has been described in the above embodiments, the present invention can of course be applied to the single type.

[0025]

As described above, according to the method of the present invention,
The piston guide that regulates the retreat limit of the piston is screwed into the bearing hole of the cylinder body to set the invalid stroke. Is eliminated and the manufacturing error of the piston guide itself is not a problem,
It is possible to easily set an invalid stroke with higher accuracy than before.

Further, according to the structure of the present invention, the gap between the step portion between the cylinder hole and the bearing hole and the piston guide is set to be larger than the length until the primary cup fully closes the relief port. It is possible to reliably carry out the setting of the invalid stroke by the method described above.

[Brief description of drawings]

FIG. 1 is an enlarged view of a main part of FIG.

FIG. 2 is a sectional front view of a hydraulic master cylinder showing an embodiment of the present invention.

FIG. 3 is a perspective view of the piston guide as viewed from the rear side.

4 is a perspective view of the piston guide of FIG. 3 viewed from the front side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hydraulic master cylinder, 2 ... Cylinder body, 3 ... Cylinder hole, 3a ... Large diameter bearing hole continuing to the cylinder hole 3b ... Screws formed in the bearing hole 3a, 4 ... Primary piston, 4a ... Primary Rear shaft of piston, 4
b ... Step of primary piston 4, 5 ... Secondary piston, 9 ... Annular piston guide screwed into bearing hole 3a, 9c ... Male thread of piston guide 9, 9d ... Tool mounting hole, 10 ... Piston guide Lock nut for fixing 9; 10a ... Tool hanging hole; 11 ... Rear seal member; 8 ...
Negative pressure booster, 12 ... Push rod, 13, 14 ... Primary cup, 15, 26 ... Secondary cup, 2
2, 24 ... Relief port, 23, 25 ... Supply port, L1 ... Invalid stroke, L2 ... Gap between step portion 3c between cylinder hole 3 and bearing hole 3a and piston guide 9

Claims (2)

[Claims] 1. A rear shaft of a piston inserted in a cylinder hole is inserted into and held by an annular piston guide mounted in a large-diameter bearing hole continuous with the cylinder hole. In a method for setting an ineffective stroke in a hydraulic master cylinder for a vehicle in which a piston urged in a hole direction is brought into contact with the piston to regulate a backward limit of the piston, the piston guide is screwed into the bearing hole. At the same time, by screwing the piston guide, the piston is advanced toward the bottom of the cylinder hole, and the primary cup fitted at the tip of the piston completely closes the relief port on the peripheral wall of the cylinder hole. By rotating the piston guide in the reverse direction and fixing the retracted position of the piston guide with a fixing means such as a lock nut. A method for setting an invalid stroke of a hydraulic master cylinder for a vehicle, characterized in that an invalid stroke is set between. 2. A rear shaft of a piston inserted in a cylinder hole is inserted into and held by an annular piston guide mounted in a large-diameter bearing hole continuous with the cylinder hole, and the piston guide is provided with the bearing hole. In a hydraulic master cylinder device for a vehicle in which a piston biased in a direction is brought into contact with the piston to regulate the retreat limit of the piston, the piston guide is attached to the bearing hole by screwing, and the piston guide While fixing the screwed position with a fixing means such as a lock nut, the primary cup fitted into the tip of the piston in the gap between the step portion of the cylinder hole and the bearing hole and the piston guide is the cylinder hole peripheral wall. A hydraulic master cylinder device for a vehicle, characterized in that the relief port is set to be longer than the length until it is fully closed.