JP2003025981A - Master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To communicate an internal space of a stopper with a pressure chamber with excellent yield of a material in a process for forming the stopper arranged in the pressure chamber between a primary piston and a secondary piston without easy change in the diameter of a front end part of the stopper. SOLUTION: A collar 39 of the stopper 27 arranged in the pressure chamber 23 between the primary piston 19 and the secondary piston 18 is formed into a flat disc shape. The internal space 45 of the stopper 27 is communicated with the pressure chamber 23 by a plurality of passing holes 40 formed on the collar 39, a plurality of recessed parts 41 formed on a rear end face of the secondary piston 18 to be communicated with the passing holes 40, and a plurality of passages 46 formed between an outer periphery of a guide projection 38 and an inner periphery of the front end part of the stopper 27 by a plurality of cut-outs provided on the outer periphery of the guide projection 38 of the secondary piston 18 to communicate the recessed parts 41 with the internal space 45 of the stopper 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of this application relates to a master cylinder used as a constituent element of a vehicle hydraulic brake device or the like.

[0002]

2. Description of the Related Art Various types of master cylinders of this type are known, and examples of compact, lightweight and low-priced cylinders are disclosed in Japanese Patent Application Laid-Open No. 11-171003.

The master cylinder described in the above publication is
A cylinder body having a cylinder bore opening at a rear end, a primary piston having at least a front portion arranged in the cylinder bore, and a cylinder body arranged in the cylinder bore so as to be located in front of the primary piston and rearward from a rear end surface. A secondary piston concentrically provided with a guide projection projecting to the first piston, and the secondary piston is arranged in a pressure chamber between the primary piston and the secondary piston, and at a rear end portion thereof in the axial direction by a predetermined stroke amount with respect to the primary piston. A rim that is movably connected, has its front end engaged with the outer periphery of the guide projection of the secondary piston at its inner periphery and centered, and has a flange that abuts the rear end surface of the secondary piston on the outer periphery of the front end. A cylindrical stopper, the collar of the stopper, and the primary piston And a return spring stretched between. The stopper is formed with a large number of slits extending from the vicinity of the rear end to the front end. By these slits, the internal space of the stopper is communicated with the pressure chamber, and when the air in the master cylinder is exhausted, the air in the internal space of the stopper is also exhausted through the pressure chamber. Then, the brake chamber is filled with the brake fluid by filling the pressure chamber with the working fluid after the exhaust.

[0004]

However, the stopper in the master cylinder described in the above publication must be formed by punching and bending a metal plate material, resulting in poor material yield. Moreover, since the diameter of the front end of the stopper can be easily reduced, the secondary piston advances with respect to the primary piston when the master cylinder operates, and when the guide projection of the secondary piston comes out of the front end of the stopper, the return spring etc. A radial external force is applied to the front end of the stopper to reduce the diameter of the front end of the stopper, and when the secondary piston subsequently retracts with respect to the primary piston, the guide protrusion does not enter the front end of the stopper well and There is a problem that the piston may not return to a predetermined return position. When the hydraulic system of the pressure chamber between the primary piston and the secondary piston fails, the front end of the primary piston moves the secondary piston forward through the stopper flange, but the contact area of the stopper flange with the primary piston is large. Is narrowed by the presence of the slit, so that there is a problem that the fracture resistance of the collar is low.

According to the invention of this application, the yield of the material in the process of forming the stopper arranged in the pressure chamber between the primary piston and the secondary piston is good, the brim resistance of the flange of the stopper is high, and the internal space of the stopper is large. An object is to have a structure in which the pressure chamber is communicated with.

Further, according to the invention of this application, the yield of the material in the process of forming the stopper arranged in the pressure chamber between the primary piston and the secondary piston is good, the brim resistance of the flange of the stopper is high, and the front end of the stopper is high. An object of the present invention is to provide a structure in which the inner space of the stopper does not change easily and the internal space of the stopper communicates with the pressure chamber.

[0007]

In order to solve the above-mentioned problems, the invention of this application is, as described in claim 1, a cylinder body having a cylinder bore opening at a rear end thereof, and at least a front portion of the cylinder body. A primary piston arranged in a cylinder bore, a secondary piston arranged in the cylinder bore so as to be located in front of the primary piston, a pressure chamber between the primary piston and the secondary piston, and a rear end And a flanged cylindrical stopper having a flange at the outer periphery of the front end that is movably connected to the primary piston in the axial direction by a predetermined stroke and is in contact with the rear end surface of the secondary piston. And a master cylinder having a return spring stretched between the primary piston and The flange of the stopper is formed in a flat disc shape, and a plurality of through holes formed in the flange and the secondary piston of the secondary piston so as to communicate with the through holes and the internal space of the stopper. The internal space of the stopper and the pressure chamber are communicated with each other by a plurality of recesses formed on the rear end surface.

In the invention of this application having such a structure, the stopper can be formed in a shape having no holes between the front and rear ends thereof. Therefore, the stopper can be formed by subjecting the metal plate material to drawing, and the material yield is good. Further, since the front end surface of the primary piston contacts the flange of the stopper over its entire surface, it is possible to increase the contact area and improve the fracture strength.

In order to solve the above-mentioned problems, according to the invention of this application, as described in claim 2, a cylinder body having a cylinder bore which is opened at the rear end, and at least a front portion is arranged in the cylinder bore. Primary piston, and a secondary piston that is disposed in the cylinder bore so as to be positioned in front of the primary piston and is concentrically provided with a guide protrusion that projects rearward from a rear end surface, the primary piston and the secondary piston Is disposed in a pressure chamber between the first piston and the primary piston so as to be movable in the axial direction by a predetermined stroke amount with respect to the primary piston, and the front end has an inner periphery thereof and an outer periphery of the guide protrusion of the secondary piston. A collar that is engaged and centered and that abuts the rear end surface of the secondary piston. In a master cylinder equipped with a flanged cylindrical stopper provided on the outer circumference of the front end and a return spring stretched between the flange of the stopper and the primary piston, a disk in which the flange of the stopper is flat And a plurality of through holes formed in the flange, a plurality of recesses formed in the rear end surface of the secondary piston so as to communicate with the through holes, and the insides of the recesses and the stopper. By a plurality of passages formed between the outer periphery of the guide protrusion and the inner periphery of the front end portion of the stopper by a plurality of notches provided on the outer periphery of the guide protrusion of the secondary piston so as to communicate with the space. The internal space of the stopper and the pressure chamber are communicated with each other.

In the invention of this application having such a structure, the stopper can be formed in a shape having no holes between the front and rear ends thereof. Therefore, the stopper can be formed by subjecting the metal plate material to drawing, and the material yield is good. Moreover, since the diameter of the front end of the stopper does not change easily, even if the secondary piston moves forward with respect to the primary piston when the master cylinder operates and the guide projection of the secondary piston comes out of the front end of the stopper, When the secondary piston retracts with respect to the primary piston, the guide protrusion accurately enters the front end portion of the stopper, and the secondary piston can return to a predetermined return position. Furthermore, since the front end surface of the primary piston contacts the flange of the stopper over its entire surface, the contact area can be increased and the fracture strength can be improved.

[0011]

1 is a sectional view of a brake master cylinder 10 according to an embodiment of the invention of this application in a normal state. As shown in FIG. 1, a cylinder body 11 of a brake master cylinder 10 is formed by connecting a portion 11A and a portion 11B, and has a cylinder bore 12 opening at a rear end (right end in FIG. 1) and hydraulic fluid inlets 13A, 13B. And outlets 14A, 14B. The inlets 13A and 13B are connected to a reservoir (not shown) that stores hydraulic fluid, and the outlets 14A and 14B are connected to a wheel brake cylinder (not shown).

A piston guide 15, a sleeve 16, and a piston guide 17 are housed in the cylinder bore 12 from the front. These piston guide 15, sleeve 1
6. The piston guide 17 is fixed to the cylinder body 11. The piston guide 15 slidably supports a secondary piston 18 having a straight cylindrical outer circumference.
The piston guide 17 slidably supports a primary piston 19 having a straight cylindrical outer circumference. A front end of the primary piston 19 is inserted into the cylinder bore 12 through an opening of the cylinder bore 12, and a rear end of the primary piston 19 is located outside the cylinder body 11.

A ring-shaped sealing cup 20 is provided between the outer circumference of the primary piston 19 and the inner circumference of the cylinder body 11, and a ring-shaped sealing cup is provided between the outer circumference of the secondary piston 18 and the inner circumference of the piston guide 15. A cup 21 is provided, and a ring-shaped sealing cup 22 is provided between the outer circumference of the secondary piston 18 and the inner circumference of the cylinder body 11. Thereby, the pressure chamber 23 for pressurizing the brake fluid by the forward movement of the primary piston 19 is formed between the primary piston 19 and the secondary piston 18, and the primary piston 1
A pressure chamber 24 is formed between the secondary piston 18 and the front end wall of the cylinder body 11 to pressurize the brake pressure by advancing the secondary piston 18 with the advance of the cylinder body 9. The pressure chamber 27 communicates with the outlet 14A via a groove or the like provided on the inner circumference of the sleeve 16, and the pressure chamber 24 communicates with the outlet 14B.

In the pressure chamber 23, the primary piston 1
9, a retainer 25 coupled to the head retainer 25, a headed rod 26 to which a rear end of the retainer 25 is coupled, a stopper 27 mounted to the headed rod 26 so as to be relatively displaceable in the axial direction by a predetermined stroke amount, and Retainer 25 and stopper 2
A return spring 28 stretched between the return spring 28 and 7 is arranged. In the pressure chamber 24, the secondary piston 1
A return spring 29 stretched between the front end wall and the front end wall of the cylinder body 11 is arranged. The mounting load of the return spring 28 is larger than the mounting load of the return spring 29. FIG. 1 of the primary piston 19
The position shown in is a predetermined return position defined by the input member (not shown) that applies a forward operation input to the primary piston 19 and is in the normal state when the input member is engaged with the primary piston 19 . In the secondary piston 18, the rear end of the stopper 27 contacts the head of the front end of the headed rod 26 and the front end of the stopper 27 is rearward of the secondary piston 18 with respect to the primary piston 19 in the return position by the return springs 28 and 29. It is positioned in the predetermined return position of FIG.

In order to allow the pressure chamber 23 to communicate with the inlet 13A when the primary piston 19 is in the predetermined return position, the passage 30 for guiding the brake fluid at the inlet 13A to the outer periphery of the piston guide 17 is provided in the cylinder body 11. A passage 31 for guiding the brake fluid in the passage 30 to the rear side of the ring-shaped sealing cup 20 is provided from the outer circumference of the piston guide 17 to the front and rear end faces, and a communication hole 32 is provided in the primary piston 19.

In order to allow the pressure chamber 24 to communicate with the inlet 13B when the secondary piston 18 is in the predetermined return position, the passage 33 for guiding the brake fluid at the inlet 13B to the outer periphery of the piston guide 15 is provided with the cylinder body 11. A passage 34 for guiding the brake fluid in the passage 33 to the rear side of the ring-shaped sealing cup 22 is provided from the outer periphery of the piston guide 15 to the front end surface, and a communication hole 35 is provided in the secondary piston 18.

In order to prevent the brake fluid in the passage 31 of the piston guide 17 from leaking out of the cylinder body 11 through the gap between the outer circumference of the primary piston 19 and the cylinder body 11, the rear end opening of the cylinder body 11 is opened. An annular groove 36 is formed on the inner circumference of the portion, and a ring-shaped sealing cup 37 is accommodated in the annular groove 36.

The shape of the rear end surface of the secondary piston 18 is shown in FIG. 2, and the shape of the front end surface of the stopper 27 is shown in FIG. As shown in FIGS. 1 to 3, the secondary piston 18
Is concentrically provided with a guide protrusion 38 protruding rearward from the rear end face. The basic shape of the guide protrusion 38 is a cylindrical shape having an outer diameter slightly smaller than the inner diameter of the front end portion of the stopper 27, and the tip outer peripheral corner portion thereof has a surface for facilitating insertion into the front end portion of the stopper 27. Has been taken.
The front end of the stopper 27 is centered by the engagement of the inner periphery of the stopper 27 with the outer periphery of the guide protrusion 38 of the secondary piston 18. The inner diameter of the hole 42 through which the shaft portion of the rod 26 at the rear end of the stopper 27 is inserted is made slightly larger than the outer diameter of the shaft portion of the rod 26, and the outer circumference of the shaft portion of the rod 26 and the inner circumference of the hole 42. The rear end of the stopper 27 is centered by this engagement.

The stopper 27 is a return spring 28.
Has a collar 39 for receiving the front end of the front end. The collar 39 is formed on a flat disc so as to make the contact area between the primary piston 19 and the primary piston 19 in contact with each other wider.

In order to exhaust the air in the brake master cylinder 10 and replace it with brake fluid, and to maintain the contact relationship between the rear end surface of the secondary piston 18 and the collar 39 of the stopper 27 during operation of the brake master cylinder 10, It is necessary that the internal space 45 of the stopper 27 and the pressure chamber 23 communicate with each other. The stopper 27 is formed by drawing a metal plate material in order to improve the material yield and prevent the diameter of the front end portion of the stopper 27 from easily changing.
There is no hole or the like that connects the internal space 45 to the pressure chamber 23 at the front and rear ends. Hole 4 in stopper 27
The clearance between the inner circumference of 2 and the outer circumference of the shaft portion of the rod 26 does not fulfill the function of communicating the internal space 45 with the pressure chamber 23.

Therefore, the internal space 45 of the stopper 27
To connect the pressure chamber 23 with the pressure chamber 23.
6 through holes 40 elongated in the circumferential direction are formed on the same circle at equal intervals, and four recesses 41 elongated in the radial direction are equally spaced in the circumferential direction on the rear end surface of the secondary piston 18. The four passages 46 are formed between the outer periphery of the guide protrusion 38 and the inner periphery of the front end of the stopper 27 by the four notches formed in the outer periphery of the guide protrusion 38 of the secondary piston 18. . 4 recesses 41 and 4 passages 4
6 and 6 are arranged in the same phase, and the radially inner end of each recess 41 communicates with the front end of each passage 46. The through hole 40 of the flange 39 of the stopper 27 is arranged radially inward of the inner circumference of the front end face of the primary piston 19, and is the same as the radially outer end of the recess 41 of the secondary piston 18. In position. Each through hole 40 communicates with any one of the four recesses 42. Therefore, the stopper 27
The internal space 45 of the passage 46, the recess 41 and the through hole 4
It communicates with the pressure chamber 23 through 0 sequentially.

Therefore, when the inlets 13A and 13B are connected to a suction type exhaust device (not shown) to exhaust the air in the pressure chambers 23 and 24, the air in the internal space 45 of the stopper 27 is also pressurized. After the exhaust, the inlets 13A and 13B are switched from the suction type exhaust device to the brake fluid filling device and communicated with each other, and the brake fluid is supplied from the brake fluid filling device to brake the inside of the brake master cylinder. Filled with liquid.

Further, since the diameter of the front end portion of the stopper 27 does not easily change, the brake master cylinder 10
When the secondary piston 18 moves forward with respect to the primary piston 19 during the operation of, and the guide protrusion 38 of the secondary piston 18 comes out from the inside of the front end portion of the stopper 27, the secondary piston 18 then moves backward with respect to the primary piston 19. Further, the guide protrusion 38 accurately enters the front end portion of the stopper 27, and the secondary piston 18 can return to a predetermined return position. Therefore, the secondary piston 18 becomes the primary piston 1
The guide protrusion 38 causes the stopper 2 to
The secondary piston 18 does not return to a predetermined return position because the secondary piston 18 does not enter the front end portion of No. 7 and does not have the problem found in the conventional master cylinder.

Two protrusions 43 are formed on the outer periphery of the collar 39 of the stopper 27, and these protrusions 43 form the sleeve 16
It is arranged in an axial groove 44 formed on the inner circumference of the. When the primary piston 19 slides rearward from the return position in FIG. 1, the projection 43 contacts the rear end of the groove 44, and this contact prevents the primary piston 19 from coming off the cylinder body 11.

Since the operation of the brake master cylinder when an operation input is applied to the primary piston 19 is substantially the same as that of the conventional master cylinder, the description thereof will be omitted.

[0026]

As described above, in the master cylinder of the invention of this application, the flange of the stopper is formed in a flat disc shape, and the plurality of through holes formed in this flange and these Since the inner space of the stopper and the pressure chamber are communicated with each other by the plurality of recesses formed in the rear end surface of the secondary piston so as to communicate with the through hole and the inner space of the stopper, The shape may be such that there are no holes between both ends. Therefore,
The stopper can be formed by subjecting a metal plate material to drawing, and the material yield is good. Further, since the front end surface of the primary piston contacts the flange of the stopper over its entire surface, it is possible to increase the contact area and improve the fracture strength.

Further, in the master cylinder of the invention of the present application, the flange of the stopper arranged in the pressure chamber between the primary piston and the secondary piston is formed in a flat disc shape, and a plurality of the flanges formed in the flange are formed. And a plurality of recesses formed on the rear end surface of the secondary piston so as to communicate with these through holes, and provided on the outer periphery of the guide protrusion of the secondary piston so as to communicate between these recesses and the internal space of the stopper. Since the internal space of the stopper and the pressure chamber are communicated by the plurality of passages formed between the outer circumference of the guide projection and the inner circumference of the front end portion of the stopper by the plurality of notches, the stopper is It may have a shape without holes between its front and rear ends. Therefore, the stopper can be formed by subjecting the metal plate material to drawing, and the material yield is good. Moreover,
Since the diameter of the front end of the stopper does not change easily, even if the secondary piston moves forward relative to the primary piston when the master cylinder operates and the guide projection of the secondary piston comes out of the front end of the stopper, the secondary piston will When retracted with respect to the primary piston, the guide protrusion accurately enters the front end portion of the stopper, and the secondary piston can return to a predetermined return position. Furthermore, since the front end surface of the primary piston contacts the flange of the stopper over its entire surface, the contact area can be increased and the fracture strength can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a master cylinder according to an embodiment of the invention of this application in a normal state.

FIG. 2 is a view showing a shape of a rear end surface of a secondary piston 18 of FIG.

3 is a diagram showing a shape of a front end face of a stopper 27 of FIG.

[Explanation of symbols]

10 ... Brake master cylinder 11 ... Cylinder body 12 ... Cylinder bore 18 ... Secondary piston 19: Primary piston 23 ... Pressure chamber 27 ... Stopper 28 ... Return spring 38 ... Guide protrusion 39 ... Tsuba 40 ... through hole 41 ... Recess 45 ... passage

Claims (2)

[Claims] 1. A cylinder body having a cylinder bore opening at a rear end thereof, a primary piston having at least a front portion arranged in the cylinder bore, and a cylinder body arranged so as to be located in front of the primary piston. A secondary piston, and is arranged in a pressure chamber between the primary piston and the secondary piston, and is connected at the rear end portion to the primary piston so as to be movable in the axial direction by a predetermined stroke amount. In a master cylinder including a flanged cylindrical stopper having a flange abutting against the end face on the outer circumference of the front end, and a return spring stretched between the flange of the stopper and the primary piston, the stopper of the stopper The tsuba is formed in the shape of a flat disk, and the multiple tsuba formed on this tsuba The internal space of the stopper and the pressure chamber are communicated with each other by through holes and a plurality of recesses formed in the rear end surface of the secondary piston so as to communicate with the through holes and the internal space of the stopper. A master cylinder characterized by 2. A cylinder body having a cylinder bore opening at a rear end thereof, a primary piston having at least a front portion arranged in the cylinder bore, and a cylinder body arranged so as to be located in front of the primary piston. And a secondary piston provided with a guide protrusion projecting rearward from the rear end face is arranged in a pressure chamber between the primary piston and the secondary piston, and a predetermined stroke with respect to the primary piston at the rear end portion. Is movably connected in the axial direction by an amount, and the front end portion is engaged with the outer periphery of the guide projection of the secondary piston at the inner periphery thereof and is centered,
A master cylinder including a flanged cylindrical stopper having a flange on the outer periphery of the front end that abuts against the rear end surface of the secondary piston, and a return spring stretched between the flange of the stopper and the primary piston. At
The flange of the stopper is formed into a flat disc shape, a plurality of through holes formed in the flange, and a plurality of through holes formed in the rear end surface of the secondary piston so as to communicate with these through holes. The recesses and the outer periphery of the guide protrusions and the inner periphery of the front end of the stopper are formed by a plurality of notches provided on the outer periphery of the guide protrusions of the secondary piston so as to communicate the recesses with the inner space of the stopper. A master cylinder, wherein the internal space of the stopper and the pressure chamber communicate with each other by a plurality of passages formed therebetween.