JP4499951B2 - Master cylinder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is used in a brake system of a vehicle or the like, and particularly suitable for a brake system equipped with an anti-skid hydraulic pressure control (ABS) device including a pump that pressurizes and recirculates hydraulic fluid on the wheel cylinder side. Related to the master cylinder.
[0002]
[Prior art]
Conventionally, as a kind of master cylinder, a cylinder body having a cylinder hole and a relief port connected to a hydraulic fluid reservoir having an opening in an inner peripheral wall of the cylinder hole, and a cylinder body that is movably inserted into the cylinder hole A piston that divides the fluid pressure generation chamber, an inner peripheral lip portion that contacts the piston, an outer peripheral lip portion that slides on the inner peripheral wall of the cylinder hole, and a base portion that connects both lip portions. And a cup seal disposed at the tip of the lip portion toward the operating position direction of the piston, and the outer peripheral lip portion passes through the opening of the relief port in response to the movement of the piston toward the operating position direction. Therefore, what is called a conventional type that cuts off the communication between the hydraulic pressure generating chamber and the hydraulic fluid reservoir via the relief port is preferable. It is known. (For example, refer to Japanese Utility Model Publication No. 62-32127, Japanese Utility Model Publication No. 8-8931, etc.)
[0003]
[Problems to be solved by the invention]
By the way, this conventional type master cylinder is structurally simpler than the center valve type master cylinder, but has a disadvantage that the cup seal is easily damaged.
[0004]
In other words, in the conventional type master cylinder, the cup seal is high from the hydraulic pressure generating chamber side at the position where the outer peripheral lip portion of the cup seal or the outer periphery of the base portion is in contact with the opening of the relief port. It has been found that when the fluid pressure is applied, a phenomenon occurs in which the outer periphery of the cup seal is locally pushed into the relief port. If such a phenomenon occurs repeatedly, particularly at the same location on the outer periphery of the cup seal, the cup seal will be damaged, such as “biting”, which will bite a portion of the outer periphery. It has also been found that it results in a poor seal.
[0005]
In addition, the occurrence of the above-described cup seal damage is caused by a brake system including an anti-skid control device (ABS device) including a pump that pressurizes hydraulic fluid back from the wheel cylinder side to the master cylinder side. In JP-A-8-150915), when the ABS device is operated, the cup seal receives a hydraulic pressure that pulsates due to the high pressure from the pump, or the master cylinder itself suddenly operates regardless of the operation of the ABS device. This tends to be prominent when the fluid pressure in the fluid pressure generating chamber rises steeply.
[0006]
The present invention has been made in view of the above-mentioned problems, and aims to provide a master cylinder with high durability by effectively preventing the occurrence of localized concentrated damage on the cup seal and extending the life of the seal. And
[0007]
[Means for Solving the Problems]
In the first aspect of the present invention, when the piston moves toward the operating position, the cup seal slides with the piston without rotating with respect to the cylinder hole, and when the piston moves toward the non-operating position. The cup seal slides while rotating with respect to the cylinder hole.
[0008]
According to a second aspect of the present invention, the piston is rotatably inserted into the cylinder hole, and one end of a winding spring is engaged with the piston, and the piston is biased toward the non-operating position. When the piston moves in the direction of the operating position, the piston rotates in the winding direction of the winding spring as the winding spring is compressed, and the contact pressure between the outer peripheral lip portion and the inner peripheral wall of the cylinder hole is reduced. When the contact pressure between the circumferential lip and the piston becomes larger, the cup seal slides with the piston without rotating with respect to the cylinder hole, and when the piston moves toward the inoperative position, the piston As the winding spring is restored, it rotates in the direction opposite to the winding direction of the winding spring, and the contact pressure between the inner peripheral lip portion and the piston is larger than the contact pressure between the outer peripheral lip portion and the inner peripheral wall of the cylinder hole. By becoming The seal moves with the piston while rotating with respect to the cylinder hole. In other words, when the piston returns to the non-operating position, the piston rotates in the opposite direction to the movement to the operating position, and eventually does not change the circumferential position with respect to the inner peripheral wall of the cylinder hole. Since the seal rotates only when the piston returns, the position in the circumferential direction changes with respect to the inner peripheral wall of the cylinder hole each time the piston reciprocates.
[0009]
According to a third aspect of the present invention, one end of a spring that urges the piston in the non-operating direction is engaged in a space defined by the inner peripheral lip portion, the outer peripheral lip portion, and the base portion of the cup seal. The locking member is mounted so as to overlap with a part of the inner peripheral lip with a minute gap, and the overlapping amount is a desired area to prevent the cup seal from falling off the piston, and the overlapping position Are arranged evenly, and the tips of the engaging members that enter the space are not in contact with the base portion.
[0010]
That is, when the piston moves in the direction of the operating position, the cup seal is not subjected to an action that increases the adhesion with the piston by the locking member, and the cup seal is prevented from rotating together with the piston. Yes. Since the contact pressure between the outer peripheral lip portion and the inner peripheral wall of the cylinder hole is reduced during the return operation of the piston to the non-operating position, the cup seal is easily rotated only during the return operation of the piston.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 shows a master cylinder according to a first embodiment of the present invention. In the master cylinder 1 according to the present embodiment, a primary piston 4 and a secondary piston 5 (hereinafter simply referred to as pistons) are movably inserted into a cylinder hole 3 of the cylinder body 2 so that two liquids are obtained. The pressure generation chambers 6 and 7 are partitioned and configured as a tandem brake master cylinder in which brake hydraulic pressure is supplied from the respective hydraulic pressure generation chambers 6 and 7 to a wheel cylinder (not shown).
[0013]
Annular cup seals 8, 9 and 10, 11 made of rubber material are mounted on the outer periphery of the pistons 4, 5, and one hydraulic pressure generating chamber 6 is located between the pistons 4, 5. The other hydraulic pressure generating chambers 7 are partitioned from the closed end 3a of the hole 3, respectively.
[0014]
The cup seal 8 partitions the fluid pressure generating chamber 6 and the fluid supply chamber 22. The cup seal 8 is positioned and held between a flange portion 4 a formed on the piston 4 and a locking member 25 that supports one end of the winding spring 18. The other end of the winding spring 18 is supported by a retainer 27 that engages with the head of a bolt member 26 coupled to the piston 4. The winding spring 18 urges the piston 4 to the right when the master cylinder 1 shown in the figure is in an inoperative state, and the hydraulic pressure generating chamber 6 is communicated with the inside of the hydraulic fluid reservoir via the relief port 12.
[0015]
Next, the secondary side cup seal 10 that partitions the fluid pressure generating chamber 7 and the fluid supply chamber 23 will be described with reference to FIG.
[0016]
The cup seal 10 includes an outer peripheral lip portion 31 that extends toward the hydraulic pressure generation chamber 7 side, an inner peripheral lip portion 32 that also extends toward the hydraulic pressure generation chamber 7 side, and the outer peripheral lip portion 31 and the inner peripheral lip portion 32. Are integrally formed with a base portion 30 connecting the two. A part of the outer peripheral surface of the outer peripheral lip portion 31 is in elastic contact with the inner peripheral wall of the cylinder hole 3, and the inner peripheral surface of the inner peripheral lip portion 32 and the base portion 30 is in elastic contact with the outer peripheral surface of the shaft portion 5 a of the piston 5. Further, the base portion 30 is supported with the outer edge portion side of the back surface in contact with the flange portion 5 b of the piston 5. The primary side cup seal 8 has the same configuration as the cup seal 10 described above.
[0017]
A locking member 40 for preventing the cup seal 10 from falling off the piston 5 is mounted on the shaft portion 5a of the piston 5. FIG. 3 shows a perspective view of the locking member 40. The locking member 40 is bent over the entire circumference on an annular surface 40 a that functions as a spring engaging portion with which a later-described winding spring 19 is engaged, and on the opposite side to the annular surface 40 a, and the inner peripheral lip portion 32 of the cup seal 10. The cup shape which has the opposing part 40b which opposes is exhibited.
[0018]
As shown in FIG. 1, one end of the winding spring 19 is pressed against the annular surface 40 a of the locking member 40, and the other end of the winding spring 19 is supported by the closed end 3 a of the cylinder hole 3. The piston 5 is urged to the right in the non-operating state of the master cylinder 1 shown in the figure, and the hydraulic pressure generating chamber 7 is communicated with the inside of the hydraulic fluid reservoir via the relief port 13. Further, one end of the winding spring 19 is engaged with its inner peripheral surface abutting on the outer peripheral surface of the shaft portion 5 a of the piston 5.
[0019]
As shown in FIG. 2, the engaging member 40 has its opposed portion 40 b intruded into a space s defined by the inner peripheral lip portion 32, the outer peripheral lip portion 31, and the base portion 30 of the cup seal 10. Is attached to the shaft portion 5a. The facing portion 40b overlaps with the inner peripheral lip portion 32 by forming a minute gap. The amount of the two overlapping each other is such that the tip of the facing portion 40b does not contact the base portion 30 and has an area that is 1/2 or more of the area of the radially outer surface 32a of the inner peripheral lip portion 32. With this overlapping amount, the cup seal 10 can be reliably prevented from falling off from the piston 5. Further, the tip of the inner peripheral lip portion 32 is in contact with the annular surface 40c opposite to the annular surface 40a constituting the spring engaging portion of the locking member 40, and the axial movement of the cup seal 10 is restricted. is doing.
[0020]
Next, the operation of the master cylinder 1 of the present embodiment configured as described above will be described.
[0021]
The hydraulic pressure generating chambers 6 and 7 are hydraulic fluid reservoirs (nipples) coupled to the boss portions 14 and 15 of the cylinder body 2 through the relief ports 12 and 13 respectively when the master cylinder shown in FIG. (Only the parts 16 and 17 are shown), but when a brake operation is performed by depressing a brake pedal (not shown), the piston 4 comes into contact with a recess 4b formed therein. The piston 5 is pushed by the output shaft 35 (not shown) and moved to the left in the figure. By the movement of the piston 4, the piston 5 connected to the piston 4 via the winding spring 18 also moves to the left in the figure. . At this time, the outer peripheral lip portion of the cup seals 8 and 10 slidably in contact with the inner peripheral wall of the cylinder hole 3 passes through the openings of the relief ports 12 and 13, whereby the liquid between the hydraulic pressure generating chambers 6 and 7 and the hydraulic fluid reservoir. Communication is interrupted. As the pistons 4 and 5 further move, brake fluid pressure is generated in the fluid pressure generating chambers 6 and 7.
[0022]
In the present embodiment, an anti-skid hydraulic pressure control device (ABS device) is provided as a brake system between the master cylinder 1 and the wheel cylinder, not shown, as is well known. When the ABS device is activated to prevent the wheels from being locked, the hydraulic fluid discharged from the wheel cylinder is released by pressurizing the hydraulic fluid by the pump included in the ABS device and returned to the hydraulic pressure generating chambers 6 and 7 side. It has a configuration.
[0023]
When the depression of the brake pedal is released or weakened, the pistons 4 and 5 are moved toward the inoperative position shown in the figure by the urging force of the winding springs 18 and 19. When the hydraulic pressure in the hydraulic pressure generating chambers 6 and 7 is temporarily lower than the atmospheric pressure (pressure on the hydraulic fluid reservoir side) as the pistons 4 and 5 return, the cup Pistons 4 which are inclined (bent) radially inward so that the outer peripheral lip portions of the seals 8 and 10 are separated from the inner peripheral wall of the cylinder hole 3, and are always in communication with the hydraulic fluid reservoir via the supply holes 20 and 21. The hydraulic fluid is replenished from the replenishing chambers 22 and 23 on the outer periphery of the body portion 5 to the hydraulic pressure generating chambers 6 and 7.
[0024]
The series of operations described above will be described in more detail particularly with respect to the secondary side. When the piston 5 moves toward the operating position, the winding spring 19 is compressed. At this time, as the winding spring 19 is compressed, the piston 5 slightly rotates in the winding direction of the winding spring 19 (the position is slightly shifted with respect to the circumferential direction). On the other hand, the cup seal 10 attached to the piston 5 generates a hydraulic pressure in the hydraulic pressure generating chamber 7 by the movement of the piston 5 in the operation position direction. It is spread out and elastically contacts with the inner peripheral wall of the cylinder hole 3 with a large contact pressure. At this time, the facing portion 40 b of the locking member 40 forms a gap with the inner peripheral lip portion 32 and the base portion 30, and the cup seal 10 is not brought into close contact with the piston 5. Accordingly, since the contact pressure between the outer peripheral lip portion 31 and the inner peripheral wall of the cylinder hole 3 is larger than the contact pressure between the inner peripheral lip portion 32 and the outer peripheral surface of the shaft portion 5a of the piston 5, the cup seal 10 Does not follow the rotation of the piston 5 but slidably contacts the inner peripheral wall of the cylinder hole 3 without changing the position in the circumferential direction. Since the piston 5 is disposed in the cylinder hole 3 so as to be sandwiched between the two springs 18 and 19, the piston 5 is rotatable with respect to the inner peripheral wall of the cylinder hole 3.
[0025]
When the piston 5 returns to the non-operating position, the piston 5 rotates in the direction opposite to the winding direction of the winding spring 19 as the winding spring 19 is restored. That is, the amount that was rotating when moving in the operating direction is returned. At this time, the outer peripheral lip portion 31 of the cup seal 10 tilts radially inward as described above and passes between the outer peripheral surface of the outer peripheral lip portion 31 and the inner peripheral wall of the cylinder hole 3 from the replenishing chamber 23. The working fluid flows into the generation chamber 7. Therefore, the contact pressure between the inner peripheral lip portion 32 and the piston 5 becomes larger than the contact pressure between the outer peripheral lip portion 31 and the inner peripheral wall of the cylinder hole 3, and the cup seal 10 together with the piston 5 The winding spring 19 rotates in the direction opposite to the winding direction.
[0026]
In the test conducted by the inventors, when the piston 5 was reciprocated a predetermined number of times at room temperature, the cup seal 10 was rotated 10 degrees to 30 degrees in the same direction. When a similar test was performed at a temperature higher than room temperature, a larger rotation angle was obtained.
[0027]
Such rotation of the cup seal 10 occurs each time the piston 5 returns in response to the operation and release of the master cylinder 1, and faces the opening of the relief port 13 on the outer peripheral surface of the outer peripheral lip portion 31. The place to do will change sequentially. Therefore, the frequency at which the same portion of the outer peripheral lip portion 31 or the base portion 30 is pushed into the opening of the relief port 13 by the hydraulic pressure in the hydraulic pressure generating chamber 7 when the master cylinder 1 is operated is reduced. Intensive damage can be prevented from occurring at the same location.
[0028]
The primary side piston 4 also rotates in the same manner as the winding spring 18 is compressed and restored. However, on the primary side, the base part of the cup seal 8 is opposed to the opposing part 25a of the locking member 25 and the piston 4. Since the pressure is narrowed between the flange portion 4a, the adhesion between the cup seal 8 and the piston 4 is higher than that of the secondary side. For this reason, the cup seal 8 is easy to rotate together when the piston 4 is operated, and is rotated in the reverse direction when returning, so that the cup seal 8 is eventually positioned in the circumferential direction with respect to the inner peripheral wall of the cylinder hole 3. Will not change.
[0029]
As in the present embodiment, when both the primary side and the secondary side are of the conventional type, in the master cylinder, the hydraulic pressure or ABS at which the cup seal 10 on the secondary side rises steeply near the corresponding relief port 13 It has been found that there is a tendency to become prominent in a state in which it is easily subjected to pulsation pressure by the device, that is, in a state in which it is easily pushed into the relief port 13, and in the present embodiment, the above-described locking member 40 is provided only on the secondary side. And the arrangement relationship between the cup seal 10 was applied. Moreover, it has been obtained by a test that if the winding directions of both the winding springs 18 and 19 are aligned, it becomes easy to rotate.
[0030]
Further, as shown in FIG. 5, the gap between the tip of the facing portion 40 b of the locking member 40 and the front surface of the base portion 30 is reduced, and the outer peripheral lip of the cup seal 10 is moved with the return operation of the piston 5. When the portion 31 tilts (this state is indicated by a one-dot chain line), the contact pressure of the cup seal 10 with respect to the piston 5 can be achieved by bringing the front surface of the base portion 30 into contact with the tip of the facing portion 40b of the locking member 40. And can be easily rotated together when the piston 5 returns.
[0031]
Next, a second embodiment of the present invention will be described. The present embodiment differs from the first embodiment in that a cup seal 50 shown in FIG. 4 is attached to the piston 5 in place of the cup seal 10.
[0032]
As with the cup seal 10, the cup seal 50 has an outer peripheral lip portion extending toward the hydraulic pressure generation chamber 7 side, an inner peripheral lip portion extending similarly toward the hydraulic pressure generation chamber 7 side, and connecting both the lip portions. The base part is integrally formed.
[0033]
As shown in FIG. 4, wing-like surfaces 51 that incline toward the front side of the base portion 50a as viewed in the clockwise direction in the drawing are connected to the back surface of the base portion 50a of the cup seal 50. A plurality (eight) are formed along the circumferential direction.
[0034]
Therefore, after the brake fluid pressure is generated, the outer peripheral lip portion of the cup seal 50 is in the inner peripheral wall of the cylinder hole 3 due to the pressure difference between the hydraulic pressure generating chamber 7 and the replenishing chamber 23 when the piston 5 is returned when the brake operation is released. The hydraulic fluid is tilted inward and radially away from the replenishing chamber 23, so that the hydraulic fluid flows between the flange portion 5 b of the piston 5 and the inner peripheral wall of the cylinder hole 3 and between the outer peripheral lip portion and the inner peripheral wall of the cylinder hole 3. The hydraulic pressure generating chamber 7 is replenished through a gap, and at this time, a part of the hydraulic fluid from the replenishing chamber 23 is moved to the wing-like surface 51 side of the back surface of the cup seal 50 generated as the outer peripheral lip portion tilts. Also flows. Then, the flow of the hydraulic fluid acts on each wing-like surface 51 and gives rotational power to the cup seal 50.
[0035]
Similar to the first embodiment, such rotation of the cup seal 50 occurs every time the piston 5 returns in response to the operation of the master cylinder 1 and the repetition of the operation release. In the surface, the location facing the opening of the relief port 13 is changed sequentially. Therefore, the frequency at which the same portion of the outer peripheral lip portion or the base portion is pushed into the opening of the relief port 13 by the hydraulic pressure in the hydraulic pressure generating chamber 7 during the operation of the master cylinder 1 is reduced. It is possible to prevent the occurrence of intensive damage at the location.
[0036]
As mentioned above, although each embodiment of this invention was described, of course, this invention is not limited to these, A various deformation | transformation is possible based on the technical idea of this invention.
[0037]
In the locking member 40 of each of the above embodiments, the opposing portion 40b is continuously formed over the entire circumference, but may be partially formed in the circumferential direction. In this case, the opposing portion 40b is formed in an even arrangement relationship with respect to the circumferential direction. This is because the opposing portion 40b receives the hydraulic pressure generated in the hydraulic pressure generating chamber 7 on its side surface, and therefore is not locked when the piston 5 moves in the direction of the operating position unless it has an equal positional relationship in the circumferential direction. This is because the member 40 may swing and come into contact with the inner peripheral lip portion 32 to press the cup seal 10 against the piston 5.
[0038]
【The invention's effect】
As described above, according to the present invention, by changing the location facing the relief port on the outer periphery of the cup seal, it is possible to prevent damage to a specific location on the outer periphery, and to greatly increase the life of the cup seal. A master cylinder that can be extended and has excellent durability can be obtained.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a master cylinder according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of a main part in FIG.
FIG. 3 is a perspective view of a locking member according to the present invention.
FIG. 4 is a perspective view of a cup seal according to a second embodiment of the present invention as seen from the back side.
FIG. 5 is an enlarged cross-sectional view of a main part for explaining a tilting operation of an outer peripheral lip portion in the master cylinder according to the first embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Master cylinder 2 Cylinder main body 3 Cylinder hole 4 (Primary) Piston 5 (Secondary) Piston 6 Fluid pressure generating chamber 7 Fluid pressure generating chamber 8 Cup seal 10 Cup seal 12 Relief port 13 Relief port 18 Winding spring 19 Winding spring 30 Base part 31 Outer lip part 32 Inner lip part 40 Locking member 40a Spring engaging part 40b Opposing part 50 Cup seal 51 Wing-like surface

Claims (8)

A cylinder body having a cylinder hole and a relief port that has an opening in the inner peripheral wall of the cylinder hole and communicates with the hydraulic fluid reservoir, and a fluid pressure generating chamber that is movably inserted into the cylinder hole and is defined inwardly A piston, an inner peripheral lip portion that contacts the piston, an outer peripheral lip portion that slidably contacts the inner peripheral wall of the cylinder hole, and a base portion that connects the two lip portions, and the tip ends of the lip portions are the pistons. The hydraulic pressure is generated through the relief port by passing the opening of the relief port in response to the movement of the piston in the direction of the actuation position. In a master cylinder provided with a cup seal that shuts off communication between the chamber and the hydraulic fluid reservoir,
When the piston moves toward the operating position, the cup seal slides with the piston without rotating with respect to the cylinder hole, and when the piston moves toward the non-operating position, A master cylinder, wherein the cup seal slides while rotating with respect to the cylinder hole . The piston is rotatably inserted into the cylinder hole, and one end of a winding spring is engaged with the piston and is urged toward the non-operating position by the winding spring. When the piston moves, the piston rotates in the winding direction of the winding spring as the winding spring is compressed, and the contact pressure between the outer peripheral lip portion and the inner peripheral wall of the cylinder hole is By becoming larger than the contact pressure between the inner peripheral lip portion and the piston, the cup seal slides with the piston without rotating with respect to the cylinder hole, and the piston moves toward the inoperative position. In this case, the piston rotates in the direction opposite to the winding direction of the winding spring as the winding spring is restored, and the contact pressure between the inner peripheral lip portion and the piston is changed to the outer peripheral lip portion. in front By made larger than the contact pressure between the inner peripheral wall of the cylinder bore, wherein the cup seal is a master cylinder according to claim 1, characterized in that slide while rotating relative to the cylinder bore with the piston. In a space defined by the inner peripheral lip portion, the outer peripheral lip portion, and the base portion, a locking member that engages with one end of a spring that biases the piston in a non-operating direction is a part of the inner peripheral lip. It is mounted so as to overlap with a minute gap, and the amount of overlap is a desired area to prevent the cup seal from falling off from the piston, and the overlapping positions are arranged uniformly, and the space 3. The master cylinder according to claim 1, wherein a tip of the engaging member that enters the base does not contact the base portion. 4. 4. The master cylinder according to claim 3, wherein the overlapping amount is an area of 1/2 or more of the inner peripheral lip. The said locking member, and a spring engaging portion into which the spring is engaged, the spring and bent over the entire circumference on the opposite side, according to claim 3 or claims and an opposing portion which faces the inner circumferential lip Item 5. The master cylinder according to item 4 . When the piston is in the non-operating position, a desired gap is provided between the facing portion, which is the tip of the locking member, and the base portion. the master cylinder according to any one claims 5 claims 3 to be filled with the tilting of the outer circumferential lip portion when said hydraulic pressure generating chamber becomes negative pressure Gimi in the process of returning to the operating position. The master cylinder is a conventional tandem master cylinder at least on the secondary side, and the locking member is provided on at least the secondary side, and the winding direction of the spring for urging each piston in the non-operation direction is the same. the master cylinder according to either one claims 6 claim 3 which is a direction. On the back side of the base portion of the cup seal, according to any one claims 1 to 7 for the wing surfaces forming a plurality of inclined along the circumferential direction with respect to axis linear of the cup seal Master cylinder.

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