JPS6133357A - Master cylinder piston - Google Patents

Abstract

PURPOSE:To make smooth sliding motion securable, by constituting a master cylinder piston with a first piston and a second piston being opposed with each other with an annular groove between, while making a support surface of the piston wider to a cylinder hole. CONSTITUTION:A front piston 11 of a master cylinder piston is divided into a first piston 13 in front and a second piston in the rear, and these pistons 13 and 14 are opposed with each other with an annular groove 15 between. A chamfered part 16, where an inner circumferential surface is partially shaved off, is formed on an outer circumference of the first piston. In addition, on the outer circumferential part of the second piston 14, there are taper parts 17 at both sides in front and in the rear, and width (a) of the outermost circumferential surface is made to be smaller than a diameter of a supply port 8 in design. Therefore, a piston 4 is supported on a wide support surface by these first and second pistons 13 and 14 so that stable sliding motion is performable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a master cylinder that operates hydraulic cylinders such as hydraulic brakes and clutches of vehicles.

For example, a disc brake on a motorcycle is operated by operating a piston of a master cylinder via an operating lever, thereby forcing pressurized hydraulic fluid to a brake caliper.

The master cylinder has a cylinder hole drilled in the main body, and a piston that is slidably fitted into the cylinder hole allows
A hydraulic chamber is defined in its front part. Further, a reservoir tank is provided, and the reservoir tank and the cylinder hole are communicated through supply boats 1 to J3 and a relief boat,
Hydraulic oil is replenished from the reservoir tank to the hydraulic chamber in accordance with the wear of the brake pad, and the hydraulic oil sent by the replenishment action is returned to the 1-arha tank.

*1: At the front end of the piston, a &lF-head cone-shaped primary cap made of f1 material is attached (-), and the piston's 1 main can j Todo's brine receptacle bulk 1 is installed.
The hydraulic oil is replenished into the hydraulic chamber and the hydraulic oil is returned from the hydraulic pressure tank to the hydraulic tank.

This J, U/L master cylinder is Special Publication No. 59-8576.
The piston of this master cylinder has a front piston part i15 and a rear piston part which directly slide into each other in the cylinder hole, and the front surface of the front piston part has the inside of the cylinder hole. A cup support body facing each other with an annular gap is provided on the circumferential surface thereof, and the cup support body supports the elastic piston cup.

Therefore, the front piston part is formed to have a diameter of 11" smaller than the diameter of the suction port, that is, the supply bow 1- which communicates with the reservoir tank, and the annular oil supply passage formed around the piston always communicates with the suction port. That's what I do.

λ plate, 1jJL shape, 1-L plate embroidery However, such a mask shilling piston has a cup support protruding from the front surface of the front screw 1, and this cup support Body (MatN4 (, j: part to front screw l-
The front part of the piston is not supported at all, so the weight of the J-tube support,
Due to inertia force, a dark weight is applied in the axial direction,
Smooth sliding movement of the piston is obstructed, and each screw I/
There was a risk of uneven wear/wear on the outer circumferential surface of the ring part.

Furthermore, since the front piston is formed to have a narrow width, it is not sufficient to support the piston in a stable state in the cylinder hole and to press the guide lead into the ground. There wasn't.

For this reason, the above publication proposes adding a piston part roughly between the front piston part and the rear piston part to widen the support surface of the screw (to stabilize the movement of the screw). However, such a bis-1 chain is difficult to process and expensive.

The present invention is an improvement on the conventional master cylinder screw 1 as described above, and in order to solve the above problems, in the present invention, the front piston part is formed into an annular shape. Consisting of a first screw and a second piston facing each other across a groove,
The first piston is provided with one or more chamfered portions on its circumferential surface.In addition, a primary cup is provided on the front end surface of the first piston, and the second piston is provided with chamfered portions at one or more places on its circumferential surface. The diameter J of the shaft 1 is made smaller, and a cutout groove is provided on the outer periphery to communicate the annular oil passage on the outer periphery of the intermediate portion of the piston with the annular groove.

As described above, in the master cylinder piston of the present invention, the front piston portion is composed of the first piston, the second piston, etc., so the supporting surface of the piston relative to the cylinder hole is wide, and the first piston and the second piston Although the two pistons are separated from each other via an annular groove, the piston is fitted into the cylinder hole coaxially and aligned, and stable and smooth IFff'lh movement is obtained.

Further, since the primary cup is directly attached to the first piston without using the cup support, a biased load does not act on the piston.

The chamfered part (J) on the circumferential surface of the first piston serves as an oil passage hole through which hydraulic oil passes from the annular groove side behind the first piston to the primary cup side in front when the piston retreats. By forming the oil passage hole with such a chamfer, the piston can be easily machined, and the piston can be manufactured on site.

The width of the second piston's outer periphery is smaller than the diameter of the repla and wart, and the outer periphery is provided with a notched groove, so that the annular oil passage and the annular groove are different from each other. No matter where it is located, it is always connected to the reservoir tank through the nappy boat, allowing smooth replenishment of hydraulic oil to the hydraulic chamber.

My husband's style 1 An embodiment of the present invention will be explained below.

FIG. 1 is a cross-sectional view of a brake stabilization link equipped with a piston according to the present invention, in which a reservoir tank 2 is integrally provided on the upper side of a cylinder body 1.

A piston 4 is inserted into the cylinder hole 3 drilled in the cylinder body 1.
The piston 4 is fitted in a reciprocating manner, and this piston 4 protrudes from the front part to define a hydraulic chamber 6 connected to the boat 5.
As the hydraulic fluid moves forward, the hydraulic fluid in the hydraulic chamber 6 is pressurized and sent to the brake caliper via the output port 5. The reservoir tank 2 and the cylinder hole 3 communicate with each other through 2 ff+N communication holes, that is, the relief boat 7 and the 1-nap lie bone 1-8, which are lined up front and back along the sliding direction of the piston 4. 4, the hydraulic oil in the reservoir tank 2 is supplied to the cylinder hole 3 through the live boat 8, and the hydraulic oil in the cylinder hole 3 is supplied to the relief 11.
It is discharged into the reservoir tank 2 through the Z door.

The piston 4 has an intermediate portion 9 having an outer diameter smaller than the inner diameter of the cylinder hole 3, and an annular oil passage 10 is formed between the intermediate portion 9 and the inner peripheral surface of the cylinder hole 3. Front piston portions 1 are located at the front and rear of the intermediate portion 9, respectively.
1 and a rear piston part 12 are provided. The outer diameter of these piston parts 11.12 is substantially equal to the inner diameter of the cylinder bore 3, and the piston 4 has both screws 1 bent part 11.1.
2 is brought into sliding contact with the inner surface of the cylinder hole 3, so that it is slidably supported and housed within the cylinder hole 3.

The front piston part 11 is divided into a first piston 13 at the front and a second piston 14 at the rear, as shown in FIG.
They are facing each other with 5 in between. On the outer periphery of the first screw ring 13, a chamfered portion 1G is formed by machining or casting, as shown in FIG. There is C. The chamfered portion 16 is provided at one or multiple locations, and in the illustrated embodiment, there are three chamfered portions 16.
It is set in place. As shown in FIG. 5, the outer circumference of the second piston 14 is provided with tapered portions 17 on both front and rear sides, and the outermost circumferential surface Il]a It's getting smaller. As shown in FIG. 4, the outer circumferential portion of the second piston 14 is also provided with a cutout groove 18, and the front open annular oil passage 10 and the annular groove portion 15 are connected to this cutout! It communicates with D via M18. The notch groove is shown in Figure 1.1.11β1;
This may be done in multiple stages (J).

On the front end surface of the first screw 1hen 13, as shown in FIG.
The diameter of the bottom of the primary cup 19 is shown in several lines in (1).
6 is smaller than the diameter of the circle 20 inscribed in J-6.

A return spring 21 is interposed between the primary cup 19 and the wall of the hydraulic chamber 6, and the piston 4 is urged rearward by this return spring 21.
The receiver is stopped by a retaining ring 22. A concave recess 2 formed between the rear piston part 12 and the intermediate part 9
3 (FIG. 2) is fitted with a secondary cup 24 to prevent leakage of hydraulic oil from the annular oil passage 10 and to prevent air from entering the annular oil passage 10. The end of the operating lever 26 is in contact with the rear *25 of the piston 4. 27 is dustproof boots.

When the operating lever 26 is not operated, the piston 4 is pushed by the return spring 21 as described above and occupies the retracted position shown in FIG. It faces the annular groove 15 between.

When the operating lever 26 is operated to push the piston 4 forward, the hydraulic fluid in the hydraulic chamber 6 is kept in the relief port 1-7 until the primary cup 19 reaches the relief boat 7.
However, after the primary cup 19 passes through the relief port 1-7, it escapes to the reservoir tank 2 through the hydraulic chamber 6.
The hydraulic fluid inside is pressurized and sent to the brake caliper through the output port 5 to operate the brake.

When the operating force of the operating lever 26 is released, the piston 4 is moved by the elastic force of the return spring 21.
However, at this time, the outer circumferential portion of the primary cup 19 bends forward due to the pressure difference generated between the hydraulic chamber 6 side and the first piston 13 side, and the outer circumferential portion of the primary cup 19 bends forward, causing a gap between the primary cup 19 and the inner surface of the cylinder hole 3 on the outside thereof. A gap is created between the two. Therefore, as the piston 4 retreats, the hydraulic oil in the reservoir tank 2 is transferred to the supply boat 8, the annular oil passage 10, the notched groove 18, the annular groove 15, and the chamfered part 1.
6 and the primary cup 19 through the gap at the outer periphery thereof, the hydraulic pressure v6 is sucked in to compensate for the reduced pressure in the hydraulic chamber 6. At this time, if excessive replenishment is performed, the excess amount is returned to the reservoir tank 2 through the relief boat 7 when the screw 4 returns to the predetermined retreat position.

When the master cylinder operates as described above, the piston 4
is supported by the first piston 13, second piston 14, and rear piston portion 12 on a relatively wide support surface, and moves stably along the inner surface of the cylinder hole 3, thereby preventing galling and uneven wear of the piston.

In addition, between the primary cup 19 and the secondary cup 24, the chamfer 16, the annular groove 15, the notch groove 18,
Since it is always in communication with the reservoir tank 2 through the annular oil passage 10 and the supply port 8, the primary cup 1
Hydraulic oil is smoothly supplied to the hydraulic chamber 6 through the outer circumference of the secondary cup 24, and the secondary cup 24 always receives hydraulic pressure to seal the gap with the cylinder hole 3, preventing leakage of hydraulic oil and air intrusion. To prevent.

9IIL Example As described above, the master cylinder piston of the present invention includes a small-diameter intermediate portion that forms an annular oil passage with the inner circumferential surface of the cylinder hole, and the above-mentioned pistons that are provided on both sides of this intermediate portion. It includes a front piston part and a rear piston part that directly slide on the inner circumferential surface of the cylinder hole, the front piston part is composed of a first piston and a second piston facing each other with an annular groove in between, and the The first piston is provided with one or more chamfered portions on its circumferential surface, and a primary cup is placed on its front end surface, and the second piston has the width of its outer circumferential portion connected to the first ply bow 1. The diameter is smaller than the inner diameter, and a cutout groove is provided on the outer periphery that connects the annular oil passage and the annular groove, so that during operation, the oil can be guided by a relatively wide support surface, that is, a long guide surface. This ensures stable and smooth reciprocating motion without galling or uneven wear.

Furthermore, the chamfered portion of the first piston, the notched groove of the second screw 1, etc. allow for easy and reliable replenishment of hydraulic oil into the hydraulic system or removal of air from the system.

Furthermore, the structure of each part is simple and processing is easy, and the whole can be molded by VI construction.

Figure 1 is a sectional view showing a motorcycle brake master cylinder equipped with a piston according to the present invention, Figure 2 is a side view of the same piston, Figure 3 FIG. 4 is a cross-sectional view taken along the lines ■--■ and rV--IV in FIG. 2, respectively, and FIG. 5 is a partially enlarged view of FIG. 2.

1...Cylinder body, 2...Reservoir tank, 3.
...Cylinder hole, 4...Piston, 5...Output capo
1-16... Hydraulic chamber, 7... Relief boat, 8
...Supply port 1~. 9... middle part, 10...
・Annular oil passage, 11...Front screw 1 heng part, 12...
Rear piston portion, 13...first piston, 14...
2nd piston, 15... Annular groove part, 16... Chamfered part, 17... -1-bar part, 18... Notch groove, 19...
...Primary cup, 20...Chamfer inscribed circle, 21
... Return spring, 22 ... Extraction ring, 23
...Annular recess, 24...Secondary cup, 25.
...Piston rear end, 26...Operation lever, 27...
Dustproof) - 1゜Figure 1 Figure 3 Figure 5

Claims (1)

[Claims] A cylinder hole in the cylinder body and a reservoir tank outside the cylinder hole are communicated through supply ports and relief ports that are lined up in front and back along the cylinder hole, and a piston is fitted into the cylinder hole to form a hydraulic chamber in the front part. The piston of the master cylinder has a small-diameter intermediate portion that forms an annular oil passage with the inner circumferential surface of the cylinder hole, and a small-diameter intermediate portion that forms an annular oil passage between the piston and the inner circumferential surface of the cylinder hole, and a small-diameter intermediate portion that is provided in the front and rear of the cylinder hole with this intermediate portion in between. The front piston includes a first piston and a second piston that face each other across an annular groove. One or more chamfered portions are provided on the circumferential surface of the second piston, and a primary cup is attached to the front end surface of the second piston. A piston for a master cylinder, characterized in that a notched groove is provided in a portion thereof to communicate the annular oil passage and the annular groove.