JP2003182559A - Master cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the invalid stroke of a plunger in a master cylinder in which the inner periphery of a cup seal whose front side faces an output liquid pressure chamber is brought into slide-contact with the outer periphery of the plunger, an annular supply chamber communicating with a reserve tank is formed between the inner periphery of a ringlike bulkhead collar fixed and arranged behind the cup seal to surround the plunger and the outer periphery of the plunger, and a relief hole communicating the supply chamber with the output liquid pressure chamber at a retraction limit position of the plunger is provided in the plunger. <P>SOLUTION: Back-up rings 33, 42 provided among the cup seals 32, 41 and the bulkhead collars 19, 21 adhere closely to the outer peripheries of the plungers 23, 24 springily. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder, and more particularly, to a master cylinder, in which a front end of the plunger faces a front end of the output hydraulic chamber. An inner periphery of the cup seal to be brought into sliding contact with the inner periphery of the ring-shaped partition collar that is fixedly arranged behind the cup seal and surrounds the plunger and an outer periphery of the plunger, and is formed in an annular shape communicating with the reserve tank. The present invention relates to an improvement of a master cylinder in which a supply chamber is formed and a relief hole is provided in the plunger for connecting the supply chamber to the output hydraulic pressure chamber at a retreat limit position of the plunger. 2. Description of the Related Art Conventionally, such a master cylinder is already known, for example, from Japanese Patent Application Laid-Open No. 3-148360. However, in the above-mentioned conventional apparatus, since the partition wall collar is in direct contact with the back surface of the cup seal, when the plunger advances from the retracted position, the relief hole is closed. Until the open end to the outer periphery of the plunger passes through the cup seal, the space between the supply chamber and the output hydraulic chamber is not shut off, so that the invalid stroke of the plunger becomes relatively large. [0004] The present invention has been made in view of such circumstances, and has as its object to provide a master cylinder capable of shortening the invalid stroke of a plunger. [0005] In order to achieve the above object, the present invention is directed to a cup having a front end facing the output hydraulic pressure chamber on the outer periphery of a plunger facing the front end of the output hydraulic pressure chamber. An annular replenishing chamber communicating with a reserve tank is provided between the inner periphery of the ring-shaped partition collar surrounding the plunger and the outer periphery of the plunger, the inner periphery of the seal being in sliding contact with the seal, and being fixedly disposed behind the cup seal. In a master cylinder formed and provided with a relief hole in the plunger that allows the supply chamber to communicate with the output hydraulic chamber at the retreat limit position of the plunger, a backup ring interposed between the cup seal and the partition wall collar is provided with a backup ring of the plunger. It is characterized by being elastically close to the outer periphery. According to such a configuration, the backup ring interposed between the cup seal and the partition collar resiliently comes into close contact with the outer peripheral surface of the plunger. When the opening end of the relief hole to the outer periphery of the plunger passes through the front end of the partition wall collar, the space between the supply chamber and the output hydraulic chamber is cut off. Can be shortened. Moreover, since the inner periphery of the backup ring is in close contact with the outer periphery of the plunger, even if the cup seal receives hydraulic pressure from the output hydraulic pressure chamber side, the inner periphery of the cup seal may not bite between the backup ring and the plunger. Absent. An embodiment of the present invention will be described below with reference to an embodiment of the present invention shown in the accompanying drawings. 1 to 7 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a tandem type master cylinder, and FIG. 2 is an enlarged longitudinal sectional view of a rear partition collar.
FIG. 3 is a sectional view taken along line 2-2 of FIG.
Is a front view of the backup ring in a natural state, FIG.
6 is an enlarged vertical sectional view of the front partition wall collar taken along line 6-6 in FIG. 4, and FIG. 7 is a sectional view taken along arrow 6 in FIG. First, in FIG. 1, a sleeve mounting hole 1 is provided in a cylinder body 11 of a tandem type master cylinder M.
2, a screw hole 13 formed larger in diameter than the sleeve mounting hole 12 and coaxially connected to the front end of the sleeve mounting hole 12;
Seal mounting hole 14 formed smaller in diameter than the sleeve mounting hole 12 and coaxially connected to the rear end of the sleeve mounting hole 12.
And a sliding hole 15 formed smaller in diameter than the seal mounting hole 14 and coaxially connected to the rear end of the seal mounting hole 14, the front end of the screw hole 13 opens at the front end of the cylinder body 11, The rear end of the sliding hole 15 opens to the rear end of the cylinder body 11. A cover member 16 having a cylindrical portion 16a that fits into the front of the sleeve mounting hole 12 is screwed into the screw hole 13. [0010] Sleeve mounting hole 12 and seal mounting hole 1
An annular step 18 is formed in the cylinder body 11 between the four. A ring-shaped rear partition collar 19, a sleeve 20, and a ring-shaped front partition collar 21 are inserted into the sleeve mounting hole 12 between the step 18 and the lid member 16 in this order from the step 18 side. The partition wall collar 19, the sleeve 20, and the front partition wall collar 21 are sandwiched and fixed to the cylinder body 11 between the cylindrical portion 16 a and the step portion 18 of the lid member 16. The sleeve 20 has a cylindrical hole 22 having an inner diameter corresponding to the sliding hole 15 and is formed in a cylindrical shape. A front portion of a rear plunger 23 is slidably fitted in the cylinder hole 22, and a rear portion of the rear plunger 23 is slidably fitted in the sliding hole 15. A rear portion of a front plunger 24 is slidably fitted in the cylinder hole 22, and a rear output hydraulic chamber 25 is formed between the rear portion and the front plungers 23, 24. A front output hydraulic chamber 26 is formed between the members 16. 2 and 3, the rear partition collar 19 is formed in a ring shape having an inner diameter corresponding to the sliding hole 15, and includes a step 18 and a sleeve. The sleeve 20 is inserted into the sleeve mounting hole 12 such that the outer peripheral portion is sandwiched between the sleeve mounting holes 20. An annular rear inner supply chamber 27 is provided between the inner periphery of the rear partition collar 19 and the outer periphery of the rear plunger 23.
Is formed between the outer periphery of the rear end of the sleeve 20, the outer periphery of the rear partition collar 19, and the inner periphery of the sleeve mounting hole 12, and an annular rear outside replenishment communicating with a reserve tank 29 mounted on the upper part of the cylinder body 11. A chamber 28 is formed. Moreover, a plurality of radially extending communication grooves 30, 30 are formed on the end face of the rear partition wall collar 19 on the side opposite to the stepped portion 18.
Are provided, and the rear inner supply chamber 27 and the rear outer supply chamber 28 communicate with each other through communication grooves 30, 30,. An annular concave portion is formed between the rear partition wall collar 19 whose outer peripheral portion is sandwiched between the step portion 18 and the sleeve 20 and the step portion between the seal mounting hole 14 and the sliding hole 15. The first to bring the inner circumference into sliding contact with the outer circumference
A cup seal 31 is mounted in the annular recess. Referring again to FIG. 1, the outer peripheral portion of the rear partition collar 19 is sandwiched between the rear portion of the sleeve 20 and the step portion 18. A second cup seal 32 for sealing both sides of the rear inner replenishing chamber 27 surrounding the rear plunger 23 in cooperation with the first cup seal 31 is disposed in front of the rear partition wall collar 19. The inner circumference of the cup seal 32 is in sliding contact with the outer circumference of the rear plunger 23, and the outer circumference of the second cup seal 32 is in elastic contact with the rear inner circumference of the sleeve 20. Moreover, the inner periphery of the backup ring 33 interposed between the second cup seal 32 and the rear partition collar 19 resiliently comes into close contact with the outer periphery of the rear plunger 23. In FIG. 4 and FIG. 5, the backup ring 33 has a slit-shaped mating surface 34 along a plane obliquely intersecting the axis of the rear plunger 23 at one position in the circumferential direction, so that the elasticity of the synthetic resin or the like is obtained. It is formed in the shape of a ring with the material having. The inner diameter of the backup ring 33 in a natural state in which the mating surfaces 34 are brought into close contact with each other is set slightly smaller than the outer diameter of the rear plunger 23. When the backup ring 33 is fitted on the rear plunger 23, the diameter of the backup ring 33 expands so as to slightly open the mating surface 34, and the backup ring 33 elastically comes into close contact with the outer periphery of the rear plunger 23. As described above, the second cup seal 32 is
The rear end of the sleeve 20 is sandwiched between the backup ring 33 that abuts on the rear bulkhead collar 19 fixed to the cylinder body 11 and a plurality of locations at equal intervals in the circumferential direction of the rear end of the sleeve 20. A plurality of support projections 3 for projecting into the second cup seal 32 and sandwiching the second cup seal 32 with the backup ring 33 are provided.
5 are protruded, and each support protrusion 35 is a sleeve 2 between each other.
At the rear end of the sleeve 0, there are provided slit-shaped notches 36 which are opened on the inner peripheral side of the sleeve 20 and open toward the second cup seal 32 side. The hydraulic pressure in the rear output hydraulic chamber 25 acts on the front surface of the second cup seal 32 through the notches 36..., And the rear outer supply chamber 28 acting on the rear side, that is, the reserve As the hydraulic pressure of the rear output hydraulic chamber 25 becomes lower than the hydraulic pressure of the brake fluid in the tank 29,
The second cup seal 32 allows the flow of the brake fluid from the rear outside supply chamber 28 to the rear output hydraulic pressure chamber 25 side. Referring to FIGS. 6 and 7, the front partition collar 21 is formed in a ring shape having an inner diameter corresponding to the cylinder hole 22. The sleeve 16 is inserted into the sleeve mounting hole 12 such that the outer peripheral portion is sandwiched between the portion 16 a and the front end of the sleeve 20. Between the inner periphery of the front partition collar 21 and the outer periphery of the front plunger 24, an annular front inner supply chamber 37 is provided.
Is formed between the outer circumference of the front end of the sleeve 20 and the outer circumference of the front partition collar 21 and the inner circumference of the sleeve mounting hole 12, and an annular front outer supply chamber 38 communicating with the reserve tank 29 is formed. Moreover, a plurality of radially extending communication grooves 39,
Are provided, and the front inner replenishing chamber 37 and the front outer replenishing chamber 38 communicate with each other through respective communication grooves 39, 39,. An annular concave portion is formed between a front partition wall collar 21 whose outer peripheral portion is sandwiched between the lid member 16 and the sleeve 20 and a front end of the sleeve 20.
A third cup seal 40 for sliding the inner circumference to the outer circumference of 4 is attached to the annular recess. A fourth cup seal 41 for sealing both sides of the front inner supply chamber 37 surrounding the front plunger 24 in cooperation with the third cup seal 40 is disposed in front of the front partition wall collar 21. The inner periphery of the fourth cup seal 41 is in sliding contact with the outer periphery of the front plunger 24, and the outer periphery of the fourth cup seal 41 is in elastic contact with the inner periphery of the rear portion of the cylindrical portion 16a of the lid member 16. Further, between the fourth cup seal 41 and the front partition wall collar 21, like the backup ring 33 interposed between the second cup seal 32 and the rear partition collar 19, the outer periphery of the front plunger 24 resiliently extends. And a backup ring 42 closely interposed therebetween. As described above, the fourth cup seal 41 is
The backup ring 42 that is in contact with the front partition wall collar 21 fixed to the cylinder body 11 is sandwiched between the back end of the cylindrical portion 16a of the lid member 16 and the circumferential direction of the rear portion of the cylindrical portion 16a. A plurality of support projections 43 projecting into the fourth cup seal 41 and sandwiching the fourth cup seal 41 between the fourth cup seal 41 and the backup ring 42 are provided at a plurality of spaced locations. Projection 43 ...
At the rear of the cylindrical portion 16a between each other, there are provided slit-shaped notches 44 which are opened on the inner peripheral side of the cylindrical portion 16a and open also toward the fourth cup seal 41 side. The hydraulic pressure in the front output hydraulic chamber 26 acts on the front surface of the fourth cup seal 41 via the notches 44..., And the front outer supply chamber 38 acts on the rear side. That is, as the hydraulic pressure of the front output hydraulic chamber 26 becomes lower than the hydraulic pressure of the brake fluid in the reserve tank 39,
The fourth cup seal 41 allows the flow of the brake fluid from the front outer supply chamber 38 to the front output hydraulic chamber 26 side. An annular groove 45 is provided on the inner surface of the sleeve mounting hole 12 at a portion corresponding to the front portion of the sleeve 20, and a pair of O-rings 4 sandwiching the annular groove 45 from both sides.
6 and 47 are mounted on the outer periphery of the sleeve 20 so as to be in close contact with the inner surface of the sleeve mounting hole 12. Moreover, the cylinder body 11 is provided with a rear output port 48 communicating with the annular groove 45, and the sleeve 20 is provided with the annular output groove 45.
Are communicated with the rear output hydraulic chamber 25 through a plurality of communication holes 49.
Is provided. An annular groove 50 is provided on the inner surface of the sleeve mounting hole 12 at a portion corresponding to an intermediate portion of the cylindrical portion 16a of the lid member 16, and a pair of O-rings 51 and 52 sandwiching the annular groove 50 from both sides. Is mounted on the outer periphery of the cylindrical portion 16a so as to be in close contact with the inner surface of the sleeve mounting hole 12.
Moreover, the cylinder body 11 is provided with a front output port 53 communicating with the annular groove 50, and the cylindrical portion 16a has
A plurality of communication holes 54 are provided to allow the annular groove 50 to communicate with the front output hydraulic chamber 26. The front part of the rear plunger 23 is formed in a cylindrical shape, and when the rear plunger 23 is at the retreat limit position as shown in FIG. A plurality of relief holes 56
Are provided at the front of the rear plunger 23. These relief holes 56 release the hydraulic pressure of the rear output hydraulic chamber 25 toward the reserve tank 29 when the rear plunger 23 retreats to the retreat limit, and when the rear plunger 23 advances from the retreat limit position, The communication with each of the relief holes 56...
Will be cut off. The front part of the front plunger 24 is also formed in a cylindrical shape, and when the front plunger 24 is at the retreat limit position as shown in FIG. A plurality of relief holes 57 through which the chamber 26 passes are provided at the front of the front plunger 24. Due to these relief holes 57, when the front plunger 24 retreats to the retreat limit, the hydraulic pressure in the front output hydraulic chamber 26 is released to the reserve tank 29 side, and the front plunger 24 advances from the retreat limit position. At this time, the communication of the relief holes 57 to the front inner supply chamber 37 is interrupted by the backup ring 42. An end face 23a provided on the rear plunger 23 facing the rear output hydraulic chamber 25 is brought into contact with a contact flange 58a provided at the rear end of a first retainer 58 formed in a cylindrical shape. A second retainer 59 is in contact with the rear surface 24a of the front plunger 24 facing the rear output hydraulic chamber 25, and a rear return spring 6 is provided between the first and second retainers 58,59.
0 is reduced. The rear return spring 60 exerts a spring force for urging the rear and front plungers 23 and 24 away from each other, and the first and second retainers 58 and 59 use the rear and front plungers 23 and 24, respectively. 2
4 is substantially fixed. The front end of a rod 61 extending coaxially with the cylinder hole 22 is engaged and connected to the center of the second retainer 59. The rear of the rod 61 is connected to the first retainer 5
8 penetrates the front end portion so as to be movable in the axial direction. In addition, at the rear end of the rod 61, an engagement flange 61a is provided at the front of the first retainer 58 so as to be able to engage from the rear.
Engages with the front portion of the first retainer 58 to regulate the maximum distance between the rear and front plungers 23 and 24. A front return spring 62 is contracted between the lid member 16 and the front plunger 24, and the front plunger 24 is urged rearward by the spring force exerted by the front return spring 62. You. A plurality of, for example, four guide grooves 63 extending along the axial direction of the cylinder hole 22 are provided on the inner surface of the sleeve 20 near the front part, and are provided on the sleeve 20 through the rear output port 48. Communication hole 49
Are open in at least one of the guide grooves 63. A second retainer 59 is provided in each of the guide grooves 63.
Are provided on the outer periphery of the guide grooves 63, respectively, and the control protrusions 59a contact with the control surfaces 64 formed at the rear ends of the guide grooves 63, respectively. The retreat limit position of the front plunger 24 urged rearward by the front return spring 62 is determined. In addition, since the maximum distance between the rear plunger 23 and the front plunger 24 is regulated as described above, the retreat limit position of the rear plunger 23 is also determined as the retreat limit position of the front plunger 24 is determined. . The rear plunger 23 is integrally and coaxially provided with an extension cylindrical portion 23b extending rearward and projecting into a negative pressure booster (not shown), and a booster shell (not shown) of the negative pressure booster. And an annular seal member 65 is interposed between the extension cylindrical portion 23b. The front end of the output rod 66 provided in the negative pressure booster is connected to the rear plunger 23 so as to swing. Next, the operation of this embodiment will be described. The front and rear sides of the second and fourth plungers 23 and 24 are brought into sliding contact with the outer periphery of the rear and front plungers 23 and 24 with the front side facing the rear and front output hydraulic chambers 25 and 26. The cup seals 32 and 41 and the rear and front plungers 2 fixed to the cylinder body 11 on the rear side of the cup seals 32 and 41
Rear and front inner replenishing chambers 2 between the outer circumferences of 3, 24
Rear and front bulkhead collars 19,2 forming 7,37
The backup rings 33 and 42 are interposed between the back and front plungers 23 and 24, respectively. Therefore, the rear and front plungers 2
When the front ends of the relief holes 56, 57 pass through the front ends of the partition collars 19, 21 when the front ends 3, 24 advance from the retracted position, the relief holes 56, 57 pass through the front ends of the partition walls 19, 21. The supply chambers 27, 37 and the rear and front output hydraulic chambers 25, 26 are shut off,
The ineffective stroke of each of the plungers 23 and 24 can be shortened, and the overall length of the master cylinder M can be shortened. Further, since the inner circumferences of the backup rings 33, 42 are in close contact with the outer circumferences of the plungers 23, 24, the second and fourth cup seals 32, 41 are located on the rear and front output hydraulic chambers 25, 26 side. Rings 33 and 42 and plungers 23 and 24
The inner periphery of the cup seal does not bite in between. Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various design changes can be made without departing from the present invention described in the appended claims. It is possible. As described above, according to the present invention, when the plunger advances from the retreat limit position, the opening end of the relief hole to the outer periphery of the plunger passes through the front end of the partition wall collar to replenish. By immediately shutting off the space between the chamber and the output hydraulic chamber, the invalid stroke of the plunger can be reduced as compared with the conventional one, and the overall length of the master cylinder can be shortened. Moreover, even when the cup seal receives the hydraulic pressure from the output hydraulic pressure chamber side, the inner periphery of the cup seal does not bite between the backup ring and the plunger.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a tandem type master cylinder. FIG. 2 is an enlarged vertical sectional view of the rear partition wall collar taken along a line 2-2 in FIG. 3; FIG. 3 is a view as viewed in the direction of arrow 3 in FIG. 2; FIG. 4 is a front view of the backup ring in a natural state. FIG. 5 is a view as seen in the direction of arrow 5 in FIG. 4; FIG. 6 is an enlarged vertical sectional view of the front partition wall collar taken along line 6-6 of FIG. 7; FIG. 7 is a view taken in the direction of arrow 7 in FIG. 6; [Description of Signs] 19, 21 ... Partition wall collars 23, 24 ... Plungers 25, 26 ... Output hydraulic pressure chambers 27, 37 ... Supply chamber 29 ... Reserve tanks 32, 41 ... Cup seals 33, 42 Backup rings 56, 57 Relief hole M Master cylinder

Claims (1)

Claims: 1. A front surface of a plunger (23, 24) facing a front end of an output hydraulic chamber (25, 26) faces the output hydraulic chamber (25, 26). Masuru cup seal (3
2, 41) is slid in contact with the inner periphery of the cup seal (32, 41).
41) and fixed behind the plunger (23,
A ring-shaped partition collar (19, 21) surrounding 24)
An annular supply chamber (27, 37) communicating with the reserve tank (29) is formed between the inner periphery of the plunger (23, 24) and the outer periphery of the plunger (23, 24).
4) A relief hole (5) for connecting the supply chamber (27, 37) to the output hydraulic chamber (25, 26) at the retreat limit position.
In the master cylinder in which the plungers (23, 24) are provided, the cup seals (32, 4) are provided.
1) and a backup ring (33, 42) interposed between the partition collars (19, 21) are provided with the plunger (2).
A master cylinder, which is elastically close to the outer periphery of (3, 24).