JP2001039292A - Plunger master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change the orientation of two piping connections arbitrarily without inhibiting air bleeding efficiency and any separate parts added. SOLUTION: The tandem type plunger master cylinder is so constructed that one of two pistons disposed in a cylinder body 10 is slidably guided on a holder connected to the opening end of the cylinder body 10 and the other piston 13 is on a sleeve 18 fitted in the cylinder body 10, with the result that the cylinder body 10 is axially shorted. A radial passage 45 connecting a circumferential passage 43 circumscribing the sleeve 18 and a primary side pressure chamber is defined intensively in the topmost position of the pressure-chamber, so that air is caused to flow from the topmost position of the pressure chamber where air is liable to stagnate into the circumferential passages 43 collectively. A piping connection 48 connecting to a wheel cylinder opens to a proper position of the circumferential passage 43. The piping work to the piping connection 48 and the other or secondary one can be thus facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder used in a brake system of a vehicle, and more particularly to a tandem type plunger type master cylinder.

[0002]

2. Description of the Related Art As a tandem type plunger type master cylinder, of two pistons (plungers) arranged in a bottomed hole of a cylinder body, a piston at an opening end side (primary side) of the hole is an opening of the hole. In some holders connected to the ends, the piston on the bottom side (secondary side) of the hole is slidably guided by a sleeve fitted in the hole. In such a master cylinder, since the sliding guide portion of the piston on the primary side can be set outside the axial direction of the cylinder body by using the holder, the axial length of the cylinder body is reduced as much as possible, It is possible to achieve a reduction in size and weight of the tandem type master cylinder and a reduction in mounting space in a vehicle. FIG. 6 shows the appearance of such a master cylinder (hereinafter, referred to as a shortened master cylinder). Reference numeral 1 denotes a cylinder body, 2 denotes a primary piston, and 3 denotes a holder. A sliding guide portion of the primary-side piston 2 is set inside a portion 3a extending outward in the axial direction of the cylinder body 1.

In the master cylinder, a piping port connected to a wheel cylinder (not shown) is usually opened at the uppermost position of the pressure chamber in consideration of air release. In this case, for the same reason, two pipe ports 4P and 4S for the primary side and the secondary side are provided in the upper part of the cylinder body 1 as shown in FIG. In this case, as shown in FIG. 7, the sleeve 5 is inserted into the hole 1a of the cylinder body 1.
Conventionally, an annular passage (circumferential passage) 6 is formed between the outer peripheral surface of the sleeve 5 and the inner peripheral surface of the hole 1a, and is provided in the sleeve 5 at equal intervals in the circumferential direction. The fluid in the primary-side pressure chamber is caused to flow out to the primary-side piping port 4P through the plurality of radial passages 7. In FIG. 7, reference numeral 8 denotes a secondary piston, and the radial passage 7 is an axial passage formed by an outer peripheral surface of the secondary piston 8 and an axial groove provided in the sleeve 5 (not shown). ) Communicates with the primary side pressure chamber.

[0004]

However, according to the shortened type master cylinder, since the axial length of the cylinder body 1 is short, as shown in FIG. , 4S are arranged close to each other, and the reservoir R is disposed almost directly above the structure, which causes a problem that the piping work for the piping ports 4P, 4S becomes extremely difficult. In order to improve the pipe workability, a part of the pipe joint 9 is separately connected to the pipe port 4P as shown by a broken line in FIG.
Although a measure is taken to correct the piping port 4P downward,
In this case, not only extra parts are required, but also extra steps are required to assemble them, which increases the cost burden, and also increases the weight of the entire master cylinder. There was a problem that there were few.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to reduce the number of piping ports without impairing air bleeding properties and adding extra parts. An object of the present invention is to provide a plunger-type master cylinder that can change the orientation of the mouth arbitrarily and thereby greatly contributes to the improvement of piping workability.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, one of two pistons disposed in a bottomed hole of a cylinder body has a holder connected to an open end of the hole. The other piston is slidably guided by the sleeve fitted in the hole, and at least one of the two pipe ports connected to the wheel cylinder is connected to the outer peripheral surface of the sleeve and the inner periphery of the hole. A tandem-type plunger-type master cylinder in which a circumferential passage formed between the first and second surfaces is opened to communicate with a pressure chamber through a radial passage provided in the sleeve. Radial passages of the sleeve are collectively provided at the uppermost position of the pressure chamber, and the one pipe port is disposed at an arbitrary position displaced in the circumferential direction with respect to the other pipe port. Characterized by being configured to be open to the passage.

In the thus configured master cylinder, since the radial passage of the sleeve is opened at the uppermost position of the pressure chamber in which the air is stored, the air in the pressure chamber flows through the circumferential hole around the sleeve through the radial hole. The air discharged into the passage is pushed by the fluid and directed to the pipe opening, and the air is discharged from the cylinder to the outside of the cylinder as it is. It is pushed out to.

In the present invention, the circumferential passage may be formed in an endless (annular) shape or an endless shape. The pipe port can be opened, while if it is endless, its starting end is aligned with the radial hole of the sleeve and its ending is aligned with the piping port. Also,
In the present invention, it is desirable to set the total passage area of the circumferential passage to be equal to or less than the opening area of the radial passage of the sleeve, so that the fluid pressure does not decrease in the circumferential passage, Air can be more reliably pushed out.

In the present invention, the sleeve may be divided so that a circumferential passage is formed in the divided element and a radial hole is provided in the divided element. It will be easier.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall structure of a tandem-type plunger-type master cylinder according to an embodiment of the present invention. In the figure, reference numeral 10 denotes a bottomed hole 11
And two pistons 12 and 13 are disposed in the hole 11 at the opening end side and the bottom side. The hole 11 has a large-diameter hole 11a on the opening end side and a small-diameter hole 11b on the bottom side.
The intermediate portion has a stepped hole shape with a medium-diameter hole portion 11c. The upper surface of the hole 11 communicates with a reservoir R that is bored in the upper wall of the cylinder body 10 so as to be spaced apart in the axial direction. Two ports 14, 15 are open. This hole 1
A holder 17 having a sliding guide portion 16 at one end for slidingly guiding one piston (primary piston) 12 is disposed in the large-diameter hole portion 11a on the opening end side of 1.
A sleeve 18 for slidingly guiding the other piston (secondary piston) 13 is provided between the medium-diameter hole portion 11c and the large-diameter hole portion 11a.

The holder 17 has an end opposite to the side having the sliding guide portion 16 inserted into the large-diameter hole 11a via a sealing member 17a. It is assembled and fixed to the cylinder body 10 by a ring screw 19 screwed to the end of 11a. The sliding guide portion 16 of the holder 17 has a first end portion 16 a for holding a seal cup (mouth cup) 20 for sealing between the outer peripheral surface of the primary-side piston 12 and an annular shape projecting to the bottom surface side of the hole 11. The guide member 16 has a plurality of radial holes 21 and an inner circumferential groove 2.
2 are provided. The radial holes 21 are provided equidistantly in the circumferential direction of the sliding guide portion 16 b, and one end thereof is opened in the inner peripheral groove 22. In the assembled state of the holder 17, the sliding guide portion 16 extends to a position outwardly separated from the opening end of the hole 11, and the axial length of the cylinder body 10 is shortened accordingly. .

The sleeve 18 has a large-diameter portion 18a and a small-diameter portion 18b connected to each other. The large-diameter portion 18a is fitted into the medium-diameter hole portion 11c of the hole 11 via a sealing member 23. The small-diameter portion 18 b extends into the holder 17. The sleeve 18 is fixed in position by abutting a step surface between the large diameter portion 18 a and the small diameter portion 18 b against the tip of the holder 17. This sleeve 18
The rear end has an enlarged inner diameter, and the second end 16b is inserted into the enlarged diameter portion. In addition, a seal cup 24 that seals between the inner peripheral surface of the sleeve 18 and the outer peripheral surface of the primary-side piston 12 is disposed in the enlarged diameter portion. It is sandwiched between the second end 16b. A vertical groove 25 is formed in the inner surface of the holder 17 in the axial direction. One end of the vertical groove 25 has one port 14 communicating with the reservoir R, and the other end has the sliding guide portion 16 (the The radial holes 21 in the two ends 16b) are each open.

A ring-shaped passage member 26 serving as a dividing element of the sleeve 18 and an inner peripheral surface of the hole 11 and an outer peripheral surface of the secondary-side piston 13 are provided behind the medium-diameter hole portion 11c of the hole 11. A seal cup 27 for sealing the space is provided. The rear end of the passage member 26 is pressed by the sleeve 18, and the outer peripheral step is abutted against an intermediate step of the medium-diameter hole portion 11 c, and the position thereof is fixed. 26 and the innermost step of the medium-diameter hole 11c. As shown in FIG. 2, the passage member 26 is provided with a plurality of radial holes 28, an outer peripheral groove 29 and an inner peripheral groove 30. The radial holes 28 are provided equidistantly in the circumferential direction, one end of which is in the outer circumferential groove 29 and the other end of which is the inner circumferential groove 30.
Each has an opening inside. The outer peripheral groove 29 is provided at a position aligned with the other port 15 communicating with the reservoir R, whereby the reservoir R and the outer peripheral surface of the secondary-side piston 13 communicate with each other through the passage member 26. It is in a state. The passage member 26
The sealing member 3 for sealing between the inner peripheral surface of the hole 11 and
A seal cup 32 for sealing between the first piston 13 and the secondary piston 13 is held.

A pair of seal cups 20 and 24 at the opening end of the hole 11 and a pair of seal cups 2 at the bottom thereof.
The sealed pressure chambers 33 and 34 are defined and formed between the primary-side piston 12 and the secondary-side piston 13 and between the secondary-side piston 13 and the bottom surface of the hole 11 respectively. The primary-side piston 12 has a cup-shaped tip at the insertion side into the hole 11, and has one pressure chamber (primary-side pressure chamber) 3.
3 has been extended into this cup-shaped part. The secondary-side piston 13 is entirely cup-shaped, and the other pressure chamber (secondary-side pressure chamber) 34 is extended to the inside of the cup-shaped portion of the secondary-side piston 13.

A return spring 36 is provided in the primary side pressure chamber 33 by using an extendable spring receiver 35a.
Both ends are abutted against the cup bottom of the primary side piston 12 and the rear end of the secondary side piston 13 via the spring receiver 35. A return spring 37 is also provided in the secondary-side pressure chamber 34 via an extendable spring receiver 35b.
And the bottom surface of the hole 11. The spring force of the return spring 36 on the primary side is set to be larger than the spring force of the return spring 37 on the secondary side. Is transmitted to the secondary-side piston 13, and the secondary-side piston 13 contracts the secondary-side return spring 37 and moves forward. An output shaft (not shown) extended from, for example, a pneumatic booster is operatively connected to a rear end portion of the primary piston 12 by using a concave portion 38 provided in the axial center thereof, In response to the operation of the pneumatic booster, the pistons 12 and 13 advance integrally, while the non-operation of the pneumatic booster returns to the original position shown in FIG. Positioned.

The distal end of the cup portion 12a of the primary piston 12 and the distal end of the secondary piston 13 are equally spaced in the circumferential direction, and are provided with a plurality of holes 39, 4 respectively.
0, and when the pistons 12 and 13 are positioned at the original positions, these holes 39 and 40 are provided.
Are two seal cups 24 on the opening end side and the hole inner side,
26 (the opening end side of the hole 11). That is, in a state where the pistons 13 and 14 are positioned at the original positions, the primary side pressure chamber 33 is provided with the hole 39 of the primary side piston 12 and the passage (the radial hole 21, The peripheral groove 22) and the vertical groove 25 between the holder 17 and the sleeve 18 communicate with the reservoir R via one port 14, and the secondary-side pressure chamber 34 communicates with the hole 40 of the secondary-side piston 13 through the passage 40. Passage (radial hole 28, outer / inner peripheral grooves 29, 30) in member 26 and other port 1
5, and communicates with the inside of the reservoir R.

As shown in FIGS. 2 and 3, a notch 41 in which the outer peripheral edge of the sleeve 18 is cut out and a step 42 of the medium-diameter hole 11c are used around the tip of the sleeve 18. Thus, an annular (endless) circumferential passage 43 is formed. A radial passage 45 is formed at the distal end of the sleeve 18 by using the radial groove 44 provided in the sleeve 18 and the rear end surface of the passage member 26.
Further, an axial passage 47 is formed on the inner surface of the sleeve 18 by utilizing the axial groove 46 provided on the inner periphery of the sleeve 18 and the outer peripheral surface of the secondary piston 13.

The radial passage 45 is provided in the cylinder body 1.
The axial passage 47 is aligned with the radial passage 45 at the uppermost position of the pressure chamber 33 at the uppermost position of the hole 11 (medium diameter hole portion 11c). Therefore, the primary-side pressure chamber 33 and the circumferential passage 43 communicate with each other via the axial passage 47 and the radial passage 45. A pipe port (primary pipe port) 48 connected to a system of wheel cylinders (not shown) is provided at a lower portion of the cylinder body 10, and the pipe port 4 is connected to the circumferential passage 43. It is open at the lowest position. In the upper part of the cylinder body 10, another piping port (secondary piping port) 49 for piping connection to a wheel cylinder (not shown) of another system is provided. It opens at the uppermost position of the chamber 34.

In the master cylinder constructed as described above, when the pneumatic booster is operated in response to the depression of the brake pedal, the output is transmitted to the primary piston 12 and the primary piston 12 and the secondary piston 12 The side piston 13 contracts the secondary side return spring 37 and moves forward integrally. Then, as the pistons 12 and 13 advance, first, the respective holes 39, 4
0 moves forward of the corresponding seal cups 24, 27,
The flow path that connects each of the pressure chambers 33 and 34 with the reservoir R is shut off, and the fluid pressure in each of the pressure chambers 33 and 34 increases. Then, the pressure fluid in the primary-side pressure chamber 33 flows out of the axial passage 47 through the radial passage 45 into the circumferential passage 43, and is further supplied from the primary-side piping port 48 to the corresponding wheel cylinder. The fluid in the secondary-side pressure chamber 34 is supplied from the secondary-side piping port 49 directly to the corresponding wheel cylinder. On the other hand, when the pedaling force on the brake pedal is released, the pistons 12 and 13 are integrally retracted by the extension of the secondary return spring 37, and return to the original position shown in FIG. At this time, when the liquid returned to each of the pressure chambers 33 and 34 is insufficient, the fluid in the reservoir R is supplied to the respective pressure chambers 33 and 34 from the two ports 14 and 15 through the corresponding flow paths.

By the way, in the brake system of a vehicle, after the master cylinder is mounted on the vehicle, the brake fluid is supplied to the brake system by using the pumping action of the master cylinder. Is pushed out by the brake fluid pushed out from the master cylinder and is discharged from the wheel cylinder at the end. At this time,
The brake fluid in the primary-side pressure chamber 33 flows out to the circumferential passage 43 through the radial passage 45 arranged at one position at the uppermost position of the hole 11, so that the air in the pressure chamber 33 flows into the pressure chamber 33. It is smoothly and reliably pushed out to the circumferential passage 43 without stagnation. Moreover, since the circumferential passage 43 is formed in an annular shape, and there is no place where air stays in the middle of the passage 43, the air pushed into the passage 43 is pushed by the fluid as it is to the primary side piping port 48. It is discharged to the hall brake side. In order to reliably push out the air, it is desirable to set the total passage area of the circumferential passage 43 to be equal to or less than the opening area of the radial passage 45, so that the fluid in the circumferential passage is The pressure does not drop and the air can be more reliably pushed out. On the other hand, the air in the secondary side pressure chamber 34 is directly pushed out to the pipe port 49 opened at the uppermost position of the pressure chamber 34, so that the air is smoothly discharged.

In the present embodiment, the primary side piping port 48 and the secondary side piping port 49 are connected to the cylinder body 1.
Since the openings are arranged 90 degrees apart from each other in the circumferential direction of 0, piping work for both can be performed smoothly and easily without interfering with each other, and piping workability is significantly improved. become. Further, in the present embodiment, since a part of the function of the sleeve 18 is provided to the passage member 26 independent of the sleeve 18, the production of the passage member 26 as well as the sleeve 18 is simplified, and accordingly, The manufacturing cost of the entire master cylinder is reduced.

In the above-described embodiment, the circumferential passage 43 between the sleeve 18 and the inner surface of the hole 11 is formed in an annular shape (endless shape). This circumferential passage is, for example, shown in FIG. In this case, a semicircular (ended) passage 43 'may be used. In this case, the fluid in the passage 43' flows in one direction, and there is no entrainment of air in the circumferential passage. Smooth discharge is possible. Also,
In the above-described embodiment, the primary-side piping port 48 is provided at the lower part of the cylinder body 10, but the location where the piping port 48 is provided is optional, and the circumferential-direction passage 43 or 43 'is optional. Can be opened.

Further, in the above embodiment, the circumferential passage 4 is formed by utilizing the cutout 41 (FIG. 2) of the sleeve 18.
3, 43 'are formed, and the radial passage 45 is formed by using the radial groove 44 (FIG. 2) and the passage member 26 provided on the distal end surface of the sleeve 18.
As shown in FIG. 5, an annular connecting member 50 having a modified cross section independent of the sleeve 18 is separately prepared, and the cylindrical portion 51 of the connecting member 50 is used as a partition wall for forming the circumferential passage 43. One or a plurality of through holes (radial passages) 52 may be provided in the uppermost part of the 51. By substituting a part of the function of the sleeve for such a connecting member 50, the production of the sleeve 18 becomes simpler, and the production cost of the entire master cylinder can be reduced.

Further, in the above-described embodiment, a combined passage of the circumferential passages 43 and 43 'and the radial passage 45 is adopted only for the piping port 48 on the primary side. A similar combination passage can be adopted for the side piping port 48. In this case, both the primary side piping port 48 and the secondary side piping port 49 may be employed, or one of them may be employed.
In any case, the orientations of the two piping ports 48 and 49 can be set at arbitrary positions in the circumferential direction of the cylinder body 10 in consideration of piping workability.

[0026]

As described above, according to the plunger-type master cylinder according to the present invention, the port directions of the two pipe ports can be arbitrarily changed without obstructing the air bleeding property and without adding extra parts. And a significant improvement in piping workability can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall structure of a plunger-type master cylinder as one embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of the present master cylinder.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 shows another embodiment of the present invention, and FIG.
It is sectional drawing similar to.

FIG. 5 is a sectional view similar to FIG. 2, but showing still another embodiment of the present invention.

FIG. 6 is a side view showing the appearance of a conventional shortened master cylinder as a partial cross section.

FIG. 7 is a sectional view taken along line BB of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cylinder main body 11 Cylinder main body hole 12 Primary side piston 13 Secondary side piston 16 Holder sliding guide part 17 Holder 18 Sleeve 26 Passage member 33 Primary side pressure chamber 34 Secondary side pressure chamber 43, 43 'Circumferential passage 45 Radius Direction passage 47 Axial passage 48 Primary-side piping port 49 Secondary-side piping port 50 Connecting member 52 Through-hole (radial flow path) of connecting member R reservoir

Continuing on the front page (72) Inventor Naganori Koshimizu 1000, Yoshida, Nakakoma-gun, Yamanashi Prefecture Inside the Yamanashi Plant, Tokiko Corporation (72) Inventor Kenji Sano Tokiko, 1000, Yoshida, Nakakoma-gun, Nakakuma-gun, Yamanashi Prefecture 3D047 BB34 BB36 CC13

Claims (5)

[Claims] 1. One of two pistons disposed in a bottomed hole of a cylinder body, one of the pistons being a holder connected to an open end of the hole, and the other piston being a sleeve fitted to the hole. The sliding guide is provided, and at least one of the two pipe ports connected to the wheel cylinder is opened in a circumferential passage formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the hole. A tandem-type plunger-type master cylinder in which the circumferential passage is communicated with a pressure chamber via a radial passage provided in the sleeve, wherein the radial passage of the sleeve is concentrated at the highest position of the pressure chamber. Wherein said one pipe port is opened in said circumferential passage at an arbitrary position displaced in the circumferential direction with respect to the other pipe port. Ta cylinder. 2. The pipe according to claim 1, wherein the circumferential passage is formed endless, and a pipe port is opened at an arbitrary position.
Plunger-type master cylinder described in 1. 3. The method according to claim 1, wherein the circumferential passage is formed to have an end, and a start end thereof is aligned with a radial hole of the sleeve, and an end end thereof is aligned with a pipe port. Plunger type master cylinder. 4. A plunger-type master cylinder according to claim 1, wherein a total passage area of the circumferential passage is set to be equal to or smaller than an opening area of the radial passage of the sleeve. . 5. The method according to claim 1, wherein the sleeve is divided, a circumferential passage is formed in the divided element, and a radial hole is provided in the divided element. The plunger-type master cylinder described.