JP2012229709A - Hydraulic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic device having a seal member with improved durability.SOLUTION: On the outer circumferential surface of a cylindrical part 52a, an annular protrusion 52c is integrally formed to protrude from the outer circumferential surface to the inner circumferential surface side of a cylinder bore 48a. The annular protrusion 52c is in close contact with the entire circumference of the inner circumferential surface of the cylinder bore 48a. When a piston 50 slides on the inner circumferential surface of the cylinder bore 48a and produces metal powder (abrasion powder) 62 on the inner circumferential surface of the cylinder bore 48a, the annular protrusion 52c of the seal member 52 removes the metal powder 62 from the inner circumferential surface of a cylinder bore 48a with the metal powder 62 produced thereon, before the outer circumferential surface of the tapered part 52b of the seal member 52 slides on the inner circumferential surface of the cylinder bore 48a with the metal powder 62 produced thereon when the seal member 52 slides on the inner circumferential surface of the cylinder bore 48a. As a result, the outer circumferential surface of the tapered part 52b are prevented from being scratched by the metal powder 62, thereby improving durability of the seal member 52.

Description

  The present invention relates to a hydraulic device, and more particularly to a technique for improving the durability of a seal member provided in the hydraulic device.

  In general, as shown in Patent Document 1 or 2, for example, a hydraulic device includes a cylinder body having a cylinder bore, and a piston slidably fitted in an opening of a cylinder bore forming an oil chamber in the cylinder body. A cylindrical tube portion fitted to the oil chamber side end of the piston, and a tapered portion that increases in diameter toward the oil chamber side from the cylinder portion, and an outer peripheral surface of the taper portion is And an elastically deformable seal member that seals the working fluid in the oil chamber by slidingly contacting the inner peripheral surface of the cylinder bore.

  Further, as described above, for example, in Patent Document 1, the hydraulic device as described above has a cylinder body fixed to a backing plate of a drum brake, and the piston is attached to one end of a brake shoe disposed on the backing plate. Sometimes used as an engaged wheel cylinder. In the wheel cylinder as described above, when pressure is applied to the hydraulic fluid supplied to the oil chamber, the piston moves to the side opposite to the oil chamber side of the cylinder bore, and pressure is applied to the hydraulic fluid in the oil chamber. When is no longer applied, the piston moves to the oil chamber side of the cylinder bore by the urging force of a return spring stretched on the brake shoe, and the piston slides on the inner peripheral surface of the cylinder bore.

Japanese Patent Laid-Open No. 10-9208 JP 09-136640 A

  However, in the hydraulic device as described above, since the piston slides on the inner peripheral surface of the cylinder bore when the hydraulic device is operated, if the number of times of operation of the hydraulic device increases, the piston and the cylinder bore The peripheral surface was worn out, and abrasion powder was sometimes generated on the inner peripheral surface of the cylinder bore. For this reason, during operation of the hydraulic device, the outer peripheral surface of the tapered portion of the taper portion of the sealing member is in a state where the wear powder is interposed between the outer peripheral surface of the tapered portion and the inner peripheral surface of the cylinder bore. Since the outer peripheral surface of the taper portion is damaged by the abrasion powder because the inner peripheral surface slides, the conventional seal member must be periodically replaced, and sufficient durability is obtained. There was no problem.

  The present invention has been made against the background described above, and an object of the present invention is to provide a hydraulic device in which the durability of the seal member is improved.

  The gist of the first invention for achieving the above object is that (a) a cylinder body having a cylinder bore and a cylinder bore that forms an oil chamber in the cylinder body are slidably fitted. A piston, a cylindrical tube part fitted to the oil chamber side end of the piston, and a taper part that increases in diameter toward the oil chamber side from the cylinder part, and an outer periphery of the taper part A hydraulic pressure device having an elastically deformable seal member that seals the hydraulic fluid in the oil chamber by a surface slidingly contacting the inner peripheral surface of the cylinder bore, and (b) on the outer peripheral surface of the cylindrical portion Is formed integrally with an annular protrusion protruding from the outer peripheral surface to the inner peripheral surface side of the cylinder bore, and (c) the annular protrusion is in close contact with the entire inner peripheral surface of the cylinder bore. It is in.

  Further, the gist of the second invention is that, in the first invention, in the state of being fitted in the cylinder bore, a lubricant is provided between the oil chamber side end of the tapered portion and the annular protrusion. An annular recess is formed to accommodate the.

  Further, the gist of the third invention is that, in the first invention or the second invention, (a) the cylinder body is fixed to a backing plate of a drum brake, and (b) the piston is a backing thereof. The drum brake is engaged with one end of a brake shoe of a drum brake disposed on the plate, and the brake shoe is expanded in accordance with the pressure of the hydraulic fluid supplied to the oil chamber in the cylinder body so that the drum brake is in a braking state. To do.

  According to the hydraulic device of the first aspect of the present invention, (b) the outer peripheral surface of the cylindrical portion is integrally formed with an annular protrusion protruding from the outer peripheral surface toward the inner peripheral surface of the cylinder bore, The annular protrusion is in close contact with the entire inner peripheral surface of the cylinder bore. For this reason, when the piston slides on the inner peripheral surface of the cylinder bore, the piston and the inner peripheral surface of the cylinder bore wear, and when wear powder is generated on the inner peripheral surface of the cylinder bore, the seal member When the outer peripheral surface of the taper portion of the seal member slides on the inner peripheral surface of the cylinder bore where the wear powder is generated, when the inner peripheral surface of the cylinder bore slides, the annular protrusion of the seal member The wear powder is removed from the inner peripheral surface of the cylinder bore where the wear powder is generated. Accordingly, the outer peripheral surface of the tapered portion is the inner peripheral surface of the cylinder bore in a state where the wear powder is not interposed between the outer peripheral surface of the tapered portion and the inner peripheral surface of the cylinder bore by the annular protrusion of the seal member. , The damage of the outer peripheral surface of the tapered portion due to the wear powder is suppressed, and the durability of the seal member is improved.

  According to the hydraulic device of the second invention, in the state fitted in the cylinder bore, an annular recess for accommodating a lubricant is provided between the oil chamber side end of the tapered portion and the annular protrusion. Since it is formed, the space between the outer peripheral surface of the tapered portion and the inner peripheral surface of the cylinder bore is suitably lubricated by the lubricant, so that the durability of the seal member is further improved.

  According to the hydraulic device of the third invention, (a) the cylinder body is fixed to a backing plate of a drum brake, and (b) the piston is a brake of the drum brake disposed on the backing plate. The brake shoe is expanded in accordance with the pressure of the hydraulic fluid that is engaged with one end of the shoe and supplied to the oil chamber in the cylinder body, thereby bringing the drum brake into a braking state. For this reason, the said hydraulic apparatus can be applied to the wheel cylinder of a drum brake, and the durability of the seal member of the wheel cylinder of the drum brake can be improved suitably.

It is a front view which shows the drum brake provided with the wheel cylinder of one Example to which this invention was applied. It is the enlarged view to which the wheel cylinder of FIG. 1 was expanded. It is a figure which shows the sealing member with which the wheel cylinder of FIG. 1 was equipped. It is the enlarged view to which a part of seal member of Drawing 3 was expanded. In the state in which the piston cylinder sliding portion and the inner peripheral surface of the cylinder bore are worn by the increase in the number of operations of the wheel cylinder in FIG. 2, and metal powder is generated on the outer peripheral surface of the sliding portion and the inner peripheral surface of the cylinder bore. FIG. 3 is an enlarged view of an enlarged portion indicated by a dashed line in the wheel cylinder of FIG. 2.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 shows a leading and trailing vehicle drum brake (hereinafter referred to as a drum brake) 12 which is a drum brake with a shoe gap automatic adjustment mechanism equipped with a wheel cylinder (hydraulic pressure device) 10 according to an embodiment of the present invention. It is a front view showing the brake drum 14 removed. The brake drum 14 is represented by two concentric circles indicated by a one-dot chain line in FIG. 1, and the circle on the center side of the drum brake 12 of the two circles indicates the inner peripheral surface 16 of the brake drum 14. Yes.

  The drum brake 12 has a substantially disk shape. For example, a backing plate 18 integrally fixed to a non-rotating member such as an axle tube, an axle housing, a suspension device (not shown), and left and right sides of the backing plate 18 are provided. A pair of brake shoes 20 and 22 disposed substantially symmetrically so as to be able to approach and separate from each other with the arcuate convex side facing outward on the outer periphery, and between one end of the pair of brake shoes 20 and 22, that is, FIG. The wheel cylinder 10 disposed between the upper end portions of the brake shoe 20 and one end portions of the pair of brake shoes 20 and 22 are stretched between the end portions of the brake shoe 20 and 22 so that the one end portions are always urged toward each other to contact the wheel cylinder 10. A return spring 24 to be contacted and a longitudinal plate-like strut spanned between one ends of the pair of brake shoes 20 and 22. 1 between the other end of the pair of brake shoes 20 and 22, that is, between the lower ends of FIG. 1, and between the lower ends of the pair of brake shoes 20 and 22. And a spring 30 whose lower end portions are always in contact with the anchor member 28.

  Each of the pair of brake shoes 20 and 22 has a flat plate shape substantially parallel to the flat flat plate portion 18a located on the inner peripheral portion of the backing plate 18, and is entirely curved in an arc shape in the front view shown in FIG. The shoe webs 32 and 34 are integrally fixed to the shoe webs 32 and 34 so that the cross-sections are substantially T-shaped along the outer peripheral side edges of the shoe webs 32 and 34 forming the arc shape thereof. The belt-shaped shoe rims 36 and 38, and the linings 40 and 42 made of a friction material integrally fixed to the outer peripheral surfaces of the shoe rims 36 and 38 with an adhesive or the like, respectively. The backing plate 18, the shoe webs 32 and 34, and the shoe rims 36 and 38 are all pressed parts that are punched from a steel plate and subjected to predetermined bending.

  The pair of brake shoes 20 and 22 are pressed against the backing plate 18 by being pressed in a direction approaching the backing plate 18 by shoe hold-down devices 44 and 46 disposed on the shoe web 32 and the shoe web 34, respectively. On the other hand, relative movement in the surface direction is held.

  As shown in FIG. 2, the wheel cylinder 10 includes a cylinder body 48 made of metal, such as cast iron, fixed to the backing plate 18, a cylinder bore 48a penetrating the cylinder body 48 in a cylindrical shape, and both ends of the cylinder bore 48a. A pair of metal pistons 50 such as cast iron and the like, which are slidably fitted in opposite openings, and an outer peripheral groove 50a formed at the end portions of the pair of pistons 50 on the side close to each other. A seal member 52 fitted to each other, a coil spring 54 that is interposed between the pair of pistons 50 and biases the pair of pistons 50 in the direction of separating each other, an inner peripheral surface of the cylinder bore 48a, and the seal member 52. An oil chamber 56 formed in a space between the pair of fitted pistons 50 and supplied with hydraulic oil (hydraulic fluid); And a respective pair of cylinder cover 58 which is constituted by the mounted elastically deformable material such as synthetic rubber between the opening and the pair of pistons 50 of the cylinder bore 48a in the cylinder body 48. In addition, on the inner peripheral surface of the cylinder bore 48a between the pair of pistons 50, hydraulic oil is not supplied from a master cylinder (not shown) into the oil chamber 56, or the hydraulic oil in the oil chamber 56 is returned to the master cylinder. A communication hole is formed.

  The seal member 52 is made of an elastically deformable material such as synthetic rubber. As shown in FIGS. 2 to 4, the seal member 52 includes a stepped cylindrical tube portion 52 a fitted into the outer peripheral groove 50 a of the piston 50 over the entire groove width of the outer peripheral groove 50 a, and the cylindrical portion thereof. A taper portion 52b having a larger diameter toward the end portion on the oil chamber 56 side from the large diameter end portion on the opposite side to the oil chamber 56 side of 52a is integrally provided. As shown in FIGS. 2 and 5, when the seal member 52 is assembled to the wheel cylinder 10, the outer peripheral surface of the tapered portion 52 b on the oil chamber 56 side seals the hydraulic oil supplied into the oil chamber 56. Thus, the cylinder bore 48a is in close contact with the entire inner circumferential surface.

  Further, as shown in FIGS. 2 to 4, the outer peripheral surface of the large-diameter end portion of the cylindrical portion 52a of the seal member 52 is from the outer peripheral surface of the end portion of the cylindrical portion 52a opposite to the oil chamber 56 side. An annular projecting portion 52c projecting toward the inner peripheral surface side of the cylinder bore 48a is integrally formed. As shown in FIGS. 2 and 5, in a state where the seal member 52 is assembled to the wheel cylinder 10, the tip of the annular protrusion 52c of the seal member 52 is in close contact with the entire inner peripheral surface of the cylinder bore 48a. . 4 shows the shape of the seal member of the conventional wheel cylinder, and the conventional seal member is not provided with the annular protrusion 52c.

  As shown in FIGS. 2 to 4, an annular recess recessed in an annular shape is formed between the end of the taper portion 52 b on the outer peripheral surface of the seal member 52 on the oil chamber 56 side and the annular protrusion 52 c. 52d is formed. As shown in FIGS. 2 and 5, in a state where the seal member 52 is assembled to the wheel cylinder 10, a lubricant 60 such as grease is accommodated in the annular recess 52 d of the seal member 52.

  As shown in FIGS. 1 and 2, the pair of pistons 50 are formed in a substantially cylindrical shape, and each of the pair of pistons 50 is arranged on the outer periphery of the end portion of the piston 50 on the oil chamber 56 side. An outer peripheral groove 50a provided, and an abutment surface 50b that abuts on one end of the brake shoes 20 and 22 by the urging force of the return spring 24 formed on the end of the piston 50 opposite to the oil chamber 56 side; A cylindrical sliding portion 50c having a diameter slightly smaller than the diameter R of the cylinder bore 48a fitted in the cylinder bore 48a so that the piston 50 is movable in the direction of the axis C of the piston 50 at an intermediate portion of the piston 50. Is provided.

  According to the drum brake 12 configured as described above, when a pressure is applied to the hydraulic oil in the oil chamber 56 by operating a brake pedal (not shown), the wheel cylinders 10 each have a pair of piston bores. 48a moves to the side opposite to the oil chamber 56 side, and ends of the pair of pistons 50 opposite to the oil chamber 56 side protrude from the opening of the cylinder body 48. As a result, the pair of brake shoes 20 and 22 are expanded, and the pair of brake shoes 20 and 22 abut against the inner peripheral surface 16 of the brake drum 14. When the operation of the brake pedal is released and no pressure is applied to the hydraulic oil in the oil chamber 56, the pair of pistons 50 are moved to the oil chamber 56 side of the cylinder bore 48a by the urging force of the return spring 24, respectively. While being returned to the original position, the pair of brake shoes 20 and 22 are separated from the inner peripheral surface 16 of the brake drum 14.

  Here, when the wheel cylinder 10 is operated, the piston 50 of the wheel cylinder 10 is operated in the direction of arrow F shown in FIG. 2 by operating the brake pedal or releasing the operation of the brake pedal as described above. The outer peripheral surface of the sliding portion 50c of the piston 50 slides on the inner peripheral surface of the cylinder bore 48a. Therefore, when the number of times of operation of the wheel cylinder 10 increases, the outer peripheral surface of the sliding portion 50c of the piston 50 and the inner peripheral surface of the cylinder bore 48a wear, and wear powder, that is, metal powder 62 is generated on the inner peripheral surface of the cylinder bore 48a. Sometimes. Hereinafter, the operation of the wheel cylinder 10 of the present embodiment in a state where the metal powder 62 is generated on the inner peripheral surface of the cylinder bore 48a will be described. FIG. 5 shows that the sliding portion 50c of the piston 50 and the inner peripheral surface of the cylinder bore 48a wear due to an increase in the number of operations of the wheel cylinder 10, and the outer peripheral surface of the sliding portion 50c and the inner periphery of the cylinder bore 48a. It is an enlarged view of wheel cylinder 10 showing the state where metal powder 62 was generated on the surface.

  As shown in FIG. 5, in the wheel cylinder 10, when pressure is applied to the hydraulic oil in the oil chamber 56 by operating the brake pedal, the seal member 52 includes the outer peripheral surface of the tapered portion 52 b and the annular protrusion 52 c. The piston 50 slides on the opposite side of the cylinder bore 48a from the oil chamber 56 side with the tip portion pressed against the entire inner peripheral surface of the cylinder bore 48a. When the seal member 52 slides on the inner peripheral surface of the cylinder bore 48a where the metal powder 62 is generated, the outer peripheral surface of the taper portion 52b of the seal member 52 slides on the inner peripheral surface of the cylinder bore 48a where the metal powder 62 is generated. Before, the metal powder 62 is removed from the inner peripheral surface of the cylinder bore 48a where the metal powder 62 is generated by the annular protrusion 52c of the seal member 52.

  As shown in FIG. 5, the seal member 52 is in a state where the outer peripheral surface of the tapered portion 52b and the tip end portion of the annular protrusion 52c are pressed against the inner peripheral surface of the cylinder bore 48a, that is, the outer periphery of the seal member 52. The lubricant 60 accommodated in the annular recess 52d on the surface is in contact with the inner peripheral surface of the cylinder bore 48a. Therefore, when the piston 50 moves in the direction of arrow F together with the seal member 52 by the operation of the wheel cylinder 10, the lubricant 60 accommodated in the annular recess 52d slides on the inner peripheral surface of the cylinder bore 48a, and the outer peripheral surface of the tapered portion 52b. And the inner peripheral surface of the cylinder bore 48a are preferably lubricated by the lubricant 60.

  According to the wheel cylinder (hydraulic pressure device) 10 of the present embodiment, the outer peripheral surface of the large-diameter end on the side opposite to the oil chamber 56 side of the cylindrical portion 52a is on the inner peripheral surface side of the cylinder bore 48a from the outer peripheral surface. An annular protrusion 52c that protrudes into the cylinder is integrally formed, and the annular protrusion 52c is in close contact with the entire inner peripheral surface of the cylinder bore 48a. For this reason, when the piston 50 slides on the inner peripheral surface of the cylinder bore 48a, the piston 50 and the inner peripheral surface of the cylinder bore 48a wear, and metal powder (wear powder) 62 is generated on the inner peripheral surface of the cylinder bore 48a. Then, when the seal member 52 slides on the inner peripheral surface of the cylinder bore 48a, the outer peripheral surface of the tapered portion 52b of the seal member 52 is sealed before sliding on the inner peripheral surface of the cylinder bore 48a in which the metal powder 62 is generated. The metal powder 62 is removed from the inner peripheral surface of the cylinder bore 48a where the metal powder 62 is generated by the annular protrusion 52c of the member 52. As a result, the outer peripheral surface of the tapered portion 52b is located within the cylinder bore 48a in a state where the metal powder 62 is not interposed between the outer peripheral surface of the tapered portion 52b and the inner peripheral surface of the cylinder bore 48a by the annular protrusion 52c of the seal member 52. Since the peripheral surface slides, scratching of the outer peripheral surface of the tapered portion 52b by the metal powder 62 is suppressed, and the durability of the seal member 52 is improved.

  Further, according to the wheel cylinder 10 of the present embodiment, in a state where the piston 50 fitted with the seal member 52 is fitted in the cylinder bore 48a, the outer periphery of the seal member 52 on the oil chamber 56 side of the tapered portion 52b. Since the annular recess 52d for accommodating the lubricant 60 is formed between the end and the annular protrusion 52c, the lubricant 60 is suitable between the outer peripheral surface of the tapered portion 52b and the inner peripheral surface of the cylinder bore 48a. Therefore, the durability of the seal member 52 is further improved.

  Further, according to the wheel cylinder 10 of the present embodiment, the cylinder body 48 is fixed to the backing plate 18 of the drum brake 12, and the piston 50 is a brake of the drum brake 12 disposed on the backing plate 18. The brake shoes 20 and 22 are expanded according to the pressure of the hydraulic oil (hydraulic fluid) that is engaged with one end of the shoes 20 and 22 and supplied to the oil chamber 56 in the cylinder body 48 to brake the drum brake 12. It is a state. For this reason, the durability of the seal member 52 of the wheel cylinder 10 of the drum brake 12 can be preferably improved.

  As mentioned above, although the Example of this invention was described based on drawing, this invention is applied also in another aspect.

  For example, the hydraulic device according to the present invention has been applied as the wheel cylinder 10 in the above-described embodiment. However, the hydraulic device according to the present invention is not limited to the wheel cylinder 10, for example, a brake master cylinder or the like. Also applies.

  Further, although the wheel cylinder 10 of the above-described embodiment is constituted by a pair of pistons 50, that is, two pistons, it may be constituted by one piston, for example, and does not limit the number of pistons.

  Further, in the wheel cylinder 10 of the above-described embodiment, the seal member 52 is integrally provided with the stepped cylindrical tube portion 52a fitted to the outer peripheral groove 50a of the piston 50 over the entire width of the outer peripheral groove 50a. The shape of the cylindrical portion 52a is not necessarily a stepped cylindrical shape, and the cylindrical portion 52a may be any shape as long as it is cylindrical.

  Although not illustrated one by one, the present invention can be implemented in variously modified and improved modes based on the knowledge of those skilled in the art.

10: Wheel cylinder (hydraulic device)
12: Drum brake 18: Backing plate 20, 22: Brake shoe 48: Cylinder body 48a: Cylinder bore 50: Piston 52: Seal member 52a: Tube portion 52b: Tapered portion 52c: Annular protrusion 52d: Annular recess 56: Oil chamber 60 :lubricant

Claims (3)

A cylinder body having a cylinder bore, a piston slidably fitted in an opening of a cylinder bore forming an oil chamber in the cylinder body, and a cylindrical shape fitted to the oil chamber side end of the piston A cylindrical portion and a tapered portion having a diameter that increases from the cylindrical portion toward the oil chamber. A hydraulic device comprising an elastically deformable seal member for sealing,
On the outer peripheral surface of the cylindrical portion, an annular protrusion protruding from the outer peripheral surface toward the inner peripheral surface of the cylinder bore is integrally formed,
The hydraulic apparatus according to claim 1, wherein the annular protrusion is in close contact with the entire inner peripheral surface of the cylinder bore.   The annular recess for containing a lubricant is formed between the oil chamber side end portion of the tapered portion and the annular protrusion in a state of being fitted into the cylinder bore. 1 hydraulic device. The cylinder body is fixed to a drum brake backing plate,
The piston is engaged with one end portion of a brake shoe of a drum brake disposed on the backing plate, and expands the brake shoe according to the pressure of hydraulic fluid supplied to an oil chamber in the cylinder body. The hydraulic device according to claim 1 or 2, wherein the drum brake is in a braking state.

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