Invention name: Disc brake and piston boot
Technical field
[0001]
　The present invention relates to, for example, a disc brake that applies braking force to a vehicle such as an automobile and a piston boot used for the disc brake.
Background technology
[0002]
　Generally, in a disc brake provided in a vehicle such as an automobile, a piston slidably inserted in a bore portion of a cylinder presses a friction pad to apply a braking force to the vehicle. An annular step is formed on the opening side of the cylinder, and a flexible piston boot is provided between the step and the piston.
[0003]
　Here, the piston boot has an annular fitting portion that fits into the step portion of the cylinder, and by including an annular metal member in the fitting portion, the assembling property to the cylinder and the durability of the piston boot are obtained. (See Patent Document 1).
Prior art literature
Patent documents
[0004]
Patent Document 1: Japanese Unexamined Patent Publication No. 2017-21166
Outline of the invention
Problems to be solved by the invention
[0005]
　However, in the piston boot containing an annular metal member, a notch is formed around the fitting portion so that a part of the metal member is exposed to the outside due to manufacturing reasons. Therefore, there is a problem that the corrosion resistance of the metal member is lowered due to the adhesion of muddy water or the like to the metal member through the notch.
Means to solve problems
[0006]
　An object of the present invention is to provide a disc brake and a piston boot used for a disc brake, which can enhance the corrosion resistance of a metal member contained in the piston boot.
[0007]
　The disc brake according to the embodiment of the present invention includes a piston that presses at least one of a pair of pads facing each other on both sides of the disc, and a bottomed bore portion that accommodates the piston so as to be movable in the axial direction. A cylinder having an annular step portion having a diameter larger than the inner diameter of the bore portion formed on the opening end side of the bore portion on which the tip of the piston protrudes, and the tip end side of the piston and the cylinder. It is provided with a piston boot which is arranged between the step portion and has a bellows portion which can be expanded and contracted with the movement of the piston, and the piston boot includes an annular metal member and is fitted to the step portion. The annular large-diameter fitting portion and the above-mentioned extending from the large-diameter fitting portion to expand the diameter from the large-diameter fitting portion to the outer peripheral side and flexing and extending toward the inner peripheral side from the large-diameter fitting portion. The bellows portion and the end portion of the bellows portion have a small diameter fitting portion formed in an annular shape having a diameter smaller than that of the large diameter fitting portion and fitted to the outer periphery of the piston, and the large diameter fitting portion of the piston boot. The joint portion is characterized by having a notch portion in which a part of the metal member is exposed to the outside at a position on the bellows portion side.
[0008]
　Further, the piston boot according to the embodiment of the present invention is accommodated in a step portion formed on the open end side of a cylinder having a bore portion provided in a caliper of a disc brake and a step portion formed in the bore portion so as to be movable in the axial direction. A piston boot having a bellows portion that is arranged between the piston and the tip end side of the piston and that can expand and contract with the movement of the piston. The piston boot includes an annular metal member in the step portion. An annular large-diameter fitting portion to be fitted and an annular large-diameter fitting portion extending from the large-diameter fitting portion to expand the diameter from the large-diameter fitting portion to the outer peripheral side and flexing toward the inner peripheral side from the large-diameter fitting portion. The piston boot has a bellows portion extending from the piston and a small diameter fitting portion formed in an annular shape having a diameter smaller than that of the large diameter fitting portion at the end of the bellows portion and fitted to the outer periphery of the piston. The large-diameter fitting portion is characterized by having a notch portion in which a part of the metal member is exposed to the outside at a position on the bellows portion side.
[0009]
　According to one embodiment of the present invention, it is possible to prevent muddy water and the like from adhering to the metal member through the notch of the large diameter fitting portion, and to improve the corrosion resistance of the metal member.
A brief description of the drawing
[0010]
FIG. 1 is a plan view of a disc brake according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the disc brake as viewed from the direction of arrow II-II in FIG.
FIG. 3 is an enlarged cross-sectional view of part III in FIG. 2 showing a piston boot.
[Fig. 4] Fig. 4 is a side view showing a piston boot as a single unit.
5 is a plan view of the piston boot as viewed from the direction of arrow VV in FIG. 4. FIG.
FIG. 6 is a cross-sectional view of the piston boot as viewed from the direction of arrow VI-VI in FIG.
FIG. 7 is a cross-sectional view of the piston boot as viewed from the direction of arrow VII-VII in FIG.
FIG. 8 is a cross-sectional view of the piston boot as viewed from the direction of arrow VIII-VIII in FIG.
Embodiment for carrying out the invention
[0011]
Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
[0012]
　The disk 1 shown in FIG. 1 rotates in the direction of arrow A in FIG. 1 together with wheels (not shown) when the vehicle travels in the forward direction, and rotates in the direction of arrow B when the vehicle moves backward. It is something to do.
[0013]
　The disc brake 2 according to the present embodiment has a carrier 3 as a mounting member fixed to a non-rotating portion (not shown) on the vehicle body side. The carrier 3 is arranged so as to straddle the outer peripheral side of the disk 1 in the axial direction at a distance from the rotation direction (circumferential direction) of the disk 1, and a pair of arm portions 3A, 3A extending in the axial direction of the disk 1, respectively. A thick support portion 3B which is provided by connecting the base end side of the arm portion 3A so as to be integrated and is fixed to the non-rotating portion of the vehicle on the inner side which is one side in the axial direction of the disc 1. It is configured to include.
[0014]
　Further, the carrier 3 is integrally formed with a reinforcing beam 3C that connects the tip ends of the arm portions 3A to each other on the outer side, which is the other side in the axial direction of the disc 1. As a result, each arm portion 3A of the carrier 3 is integrally connected by the support portion 3B on the inner side of the disc 1, and is integrally connected by the reinforcing beam 3C on the outer side of the disc 1. Each arm 3A is formed with pad guides (not shown) having a U-shaped cross section for guiding the friction pads 8 described later in the axial direction of the disc 1 on both sides in the axial direction sandwiching the disc 1.
[0015]
　The caliper 4 is slidably supported by the carrier 3. The caliper 4 extends from the inner leg 4A to the outer side of the disc 1 so as to straddle the outer peripheral side of the disc 1 between the inner leg 4A provided on the inner side of the disc 1 and each arm 3A of the carrier 3. It is composed of a bridge portion 4B provided and an outer leg portion 4C extending inward in the radial direction of the disc 1 from the outer side which is the tip side of the bridge portion 4B and having a bifurcated claw portion 4C1 on the tip side. There is. The inner leg portion 4A of the caliper 4 is provided with a cylinder 9 and a piston 11 which will be described later.
[0016]
　Further, the inner leg portion 4A is provided with a pair of mounting portions 4D protruding in the rotational direction of the disc 1. Each of these mounting portions 4D slidably supports the entire caliper 4 with respect to each arm portion 3A of the carrier 3 via a sliding pin 5. The sliding pin 5 is fastened to each mounting portion 4D of the caliper 4 by using bolts 6. The tip end side of each sliding pin 5 is slidably inserted into a pin hole (not shown) formed in each arm portion 3A of the carrier 3 along the axial direction of the disk 1. Protective boots 7 are attached between each arm portion 3A and each sliding pin 5 to prevent rainwater or the like from entering between the sliding pin 5 and the pin hole of the arm portion 3A.
[0017]
　The friction pads 8 are arranged in pairs so as to face both sides (inner side and outer side) of the disc 1. The friction pads 8 on the inner side and the outer side have a lining 8A that receives a frictional force due to contact with the disc 1. When the disc brake 2 is activated, the brake fluid pressure is supplied into the bore portion 9A of the cylinder 9 described later, and the piston 11 moves toward the disc 1. As a result, the friction pad 8 on the inner side is pressed against the disc 1 by the piston 11, and the caliper 4 is displaced toward the inner side by the reaction force from the piston 11. As a result, the claw portion 4C1 of the outer leg portion 4C presses the friction pad 8 on the outer side against the disc 1, and the friction pads 8 on the inner side and the outer side are pressed against both sides of the disc 1 to control the disc 1. Power is given.
[0018]
　The cylinder 9 is provided on the inner leg portion 4A of the caliper 4. The cylinder 9 has a bore portion 9A formed of a bottomed circular hole, and a piston 11 is slidably inserted in the bore portion 9A. One side of the cylinder 9 in the axial direction is the bottom portion 9B of the bore portion 9A, and a brake fluid passage 9C penetrating in the axial direction is formed in the central portion of the bottom portion 9B. Brake fluid pressure is supplied and discharged to the bore portion 9A of the cylinder 9 through the brake fluid passage 9C. The other side of the cylinder 9 in the axial direction is an open end 9D, and the piston 11 is inserted into the bore portion 9A through the open end 9D.
[0019]
　On the open end 9D side of the cylinder 9, an annular step portion 9E having a diameter larger than the inner diameter of the bore portion 9A is formed concentrically with the bore portion 9A. The step portion 9E is composed of a small diameter step portion 9E1 located on the bottom 9B side and a large diameter step portion 9E2 having a diameter dimension larger than the diameter dimension of the small diameter step portion 9E1 and adjacent to the small diameter step portion 9E1 in the axial direction. Has been done. The large-diameter fitting portion 12A of the piston boot 12 described later is fitted in the small-diameter step portion 9E1, and the bellows portion 12B of the piston boot 12 described later is housed in the large-diameter step portion 9E2. An annular seal groove 9F is formed over the entire circumference at a position on the bottom portion 9B side of the step portion 9E of the cylinder 9. An O-ring 10 is attached to the seal groove 9F, and the O-ring 10 seals between the inner peripheral surface of the bore portion 9A of the cylinder 9 and the outer peripheral surface 11B of the piston 11 described later.
[0020]
　The piston 11 is housed in the bore portion 9A of the cylinder 9 so as to be movable in the axial direction. The piston 11 is formed in a bottomed cylindrical shape, and the tip 11A of the piston 11 protrudes from the bore portion 9A and is in contact with the friction pad 8. The brake fluid pressure is supplied into the bore portion 9A through the brake fluid passage 9C of the cylinder 9, so that the piston 11 protrudes from the bore portion 9A and presses the friction pad 8 toward the disc 1. An annular groove 11C is formed on the outer peripheral surface 11B on the tip end 11A side of the piston 11 over the entire circumference. A small diameter fitting portion 12C of the piston boot 12, which will be described later, is fitted in the annular groove 11C.
[0021]
　Next, the piston boots used in the present embodiment will be described.
[0022]
　As shown in FIGS. 2 and 3, the piston boot 12 is provided between the tip 11A side of the piston 11 and the small diameter step portion 9E1 of the cylinder 9. The piston boot 12 expands and contracts as the piston 11 moves, and seals between the inner peripheral surface of the cylinder 9 (bore portion 9A) and the outer peripheral surface 11B of the piston 11, so that foreign matter such as dust and rainwater invades. It plays a role in preventing. As shown in FIGS. 4 to 8, the piston boot 12 is integrally molded using a flexible material such as rubber or synthetic resin, and has a large diameter fitting portion 12A, a metal member 13, and a bellows portion 12B. , A small diameter fitting portion 12C, and an annular protrusion 12D.
[0023]
　The large-diameter fitting portion 12A as the fitting portion is provided so as to be fitted to the small-diameter step portion 9E1 of the cylinder 9. The large-diameter fitting portion 12A is formed in an annular shape (cylindrical shape) corresponding to the small-diameter step portion 9E1 of the cylinder 9, and contains (embeds) an annular metal member 13. Here, the metal member 13 is an annular body having a diameter larger than the inner diameter of the bore portion 9A of the cylinder 9 and a diameter smaller than the inner diameter of the small diameter step portion 9E1 and is integrally molded with the piston boot 12. The metal member 13 increases the rigidity of the large diameter fitting portion 12A. The outer peripheral surface 12A1 of the large-diameter fitting portion 12A is provided with an annular outer peripheral protrusion 12A2 over the entire circumference. The outer peripheral protrusion 12A2 is fitted to the annular recessed portion 9G formed on the inner peripheral surface of the small diameter step portion 9E1 of the cylinder 9 to pull out the large diameter fitting portion 12A with respect to the small diameter step portion 9E1 of the cylinder 9. I'm stopping.
[0024]
　The bellows portion 12B extends from the large-diameter fitting portion 12A toward the open end 9D of the cylinder 9 and is housed in the large-diameter step portion 9E2 of the cylinder 9. The bellows portion 12B extends from the large-diameter fitting portion 12A toward the open end 9D side of the cylinder 9, and extends from the outer peripheral surface 12A1 of the large-diameter fitting portion 12A to the outer peripheral side (outside in the radial direction) with the extending portion 12B1. Including the telescopic portion 12B3 which is folded back inward in the radial direction from the outer peripheral end 12B2 of the extending portion 12B1 and bends and extends in a bellows shape toward the inner peripheral side of the inner peripheral surface 12A3 of the large diameter fitting portion 12A. It is configured. In this case, the outer peripheral end 12B2 of the extending portion 12B1 is arranged radially outside the outer peripheral surface 12A1 of the large-diameter fitting portion 12A (see FIG. 3). The small diameter fitting portion 12C is provided at the radial inner end of the telescopic portion 12B3 constituting the bellows portion 12B. The small-diameter fitting portion 12C is formed in an annular shape having a smaller diameter than the large-diameter fitting portion 12A, and is fitted in the annular groove 11C of the piston 11.
[0025]
　The annular protrusion 12D is provided on the inner peripheral surface 12A3 of the large diameter fitting portion 12A. The annular projecting portion 12D projects in an annular shape from the inner peripheral surface 12A3 of the large-diameter fitting portion 12A over the entire circumference and abuts on the outer peripheral surface 11B of the piston 11 to center the piston 11 with respect to the bore portion 9A of the cylinder 9. The sex is secured. Here, as shown in FIG. 3, assuming that the center of the cross section of the metal member 13 contained in the large-diameter fitting portion 12A is P, the annular protrusion 12D is the center of the cross section of the metal member 13 in the axial direction of the piston 11. It is formed at a position closer to the bellows portion 12B by the dimension L than P.
[0026]
　The bellows portion 12B of the piston boot 12 has greater flexibility and is more easily deformed than the large-diameter fitting portion 12A including the metal member 13. Therefore, when the molded piston boot 12 is removed from the mold, it is removed from the mold in order from the easily deformable bellows portion 12B to the hard-to-deform large-diameter fitting portion 12A. On the other hand, since the annular protrusion 12D is arranged on the bellows portion 12B side of the cross-sectional center P of the metal member 13, it can be easily removed from the mold by deforming it together with the bellows portion 12B. It is composed.
[0027]
　The plurality of cutout portions 12E are provided at a portion where the large-diameter fitting portion 12A and the extending portion 12B1 of the bellows portion 12B intersect, that is, a portion of the large-diameter fitting portion 12A on the bellows portion 12B side. These plurality of notched portions 12E are arranged at a plurality of locations (for example, 6 locations) apart from each other in the circumferential direction of the metal member 13. At the positions of these notches 12E, the metal member 13 is not covered with the rubber of the piston boot 12, and the metal member 13 is exposed to the outside. That is, the large-diameter fitting portion 12A of the piston boot 12 has a plurality of cutout portions 12E in which a part of the metal member 13 is exposed to the outside at a position on the bellows portion 12B side.
[0028]
　Here, the piston boot 12 including the annular metal member 13 is manufactured by using a mold (none of which is shown) including a lower mold, an upper mold, and a medium mold. When manufacturing the piston boot 12, a rubber material is injected into the mold in a state where the metal member 13 is positioned (restrained) with respect to the lower mold using a plurality of positioning tools (not shown). As a result, the piston boot 12 including the metal member 13 can be integrally molded. Therefore, a plurality of cutout portions 12E are formed in the portion of the large-diameter fitting portion 12A corresponding to the positioning tool, and in each of these cutout portions 12E, a part of the metal member 13 is not covered with the rubber material. It is exposed to the outside.
[0029]
　In this case, the outer peripheral end 12B2 of the extending portion 12B1 constituting the bellows portion 12B has a diameter expanded to the outer peripheral side (diameter outer side) of the outer peripheral surface 12A1 of the large diameter fitting portion 12A. Therefore, each notch 12E provided in the portion of the large-diameter fitting portion 12A on the bellows portion 12B side is covered by the bellows portion 12B in the axial direction of the piston 11. As a result, even if the muddy water is scattered toward the piston 11 while the vehicle is running, the muddy water is blocked by the bellows portion 12B of the piston boots 12 and does not reach the large diameter fitting portion 12A. Therefore, the corrosion resistance of the metal member 13 can be improved by suppressing the infiltration of muddy water into each notch 12E formed in the large diameter fitting portion 12A and protecting the metal member 13 from the muddy water. There is.
[0030]
　Further, the bellows portion 12B arranged between the large-diameter fitting portion 12A and the small-diameter fitting portion 12C of the piston boot 12 extends from the large-diameter fitting portion 12A toward the open end 9D of the cylinder 9. It is composed of a 12B1 and an expansion / contraction portion 12B3 that is folded back inward in the radial direction from the outer peripheral end 12B2 of the extension portion 12B1 and extends to the small diameter fitting portion 12C. That is, the bellows portion 12B is bent in the radial direction at a position shifted toward the open end 9D of the cylinder 9 from the large-diameter fitting portion 12A and the small-diameter fitting portion 12C in the axial direction of the piston 11. As a result, the diameter of the piston boot 12 is larger than that of the piston boot according to Patent Document 1, in which the bellows portion is radially bent and arranged between the large diameter fitting portion and the small diameter fitting portion. The dimension in the direction can be kept small. As a result, the layout of the cylinder 9 on which the piston boot 12 is provided on the open end 9D side can be narrowed, and the caliper 4 can be made lighter.
[0031]
　Here, when manufacturing a piston boot containing an annular metal member, a mold (molding mold) including a lower mold, an upper mold, a medium mold, or the like is usually used. Then, by injecting a rubber material into the mold (cavity) in a state where the annular metal member is positioned (restrained) with respect to the lower mold or the like using a positioning jig, the piston boot containing the metal member is contained. Is integrally molded. However, when the metal member is positioned using the positioning jig, the portion of the metal member in contact with the positioning jig is exposed to the outside without being covered with the rubber material. Since a plurality of positioning jigs are usually arranged in the circumferential direction of the metal member, a plurality of notches in which a part of the metal member is exposed to the outside are formed in the molded piston boot. Therefore, if the muddy water is scattered toward the piston while the vehicle is running, the muddy water infiltrates into each notch of the piston boot, and there is a problem that the corrosion resistance of the metal member is lowered.
[0032]
　On the other hand, in the piston boot 12 according to the present embodiment, even if a plurality of cutout portions 12E are formed around the large diameter fitting portion 12A due to manufacturing reasons, each of the cutout portions 12E is fitted with a large diameter. It is arranged at the portion of the joint portion 12A on the bellows portion 12B side. As a result, each notch portion 12E can be covered by the bellows portion 12B whose diameter is expanded from the large diameter fitting portion 12A to the outer peripheral side (outward in the radial direction). Therefore, the muddy water scattered on the piston 11 when the vehicle is running can be blocked by the bellows portion 12B, and the muddy water can be prevented from adhering to the metal member 13 through each notch portion 12E.
[0033]
　The disc brake 2 according to the present embodiment has the above-described configuration, and next, the operation of the disc brake 2 will be described.
[0034]
　When the brake operation is performed while the vehicle is running, the brake fluid pressure is supplied to the bore portion 9A of the cylinder 9 formed in the caliper 4 through the brake fluid passage 9C. As a result, the piston 11 moves in the bore portion 9A of the cylinder 9 toward the open end 9D side and presses the friction pad 8 on the inner side. Therefore, the caliper 4 is displaced toward the inner side by the reaction force from the piston 11. As a result, the claw portion 4C1 of the outer leg portion 4C presses the friction pad 8 on the outer side against the disc 1, and the friction pads 8 on the inner side and the outer side are pressed against both sides of the disc 1, so that the braking force is applied to the vehicle. Is given. At this time, the piston boot 12 expands and contracts (elastically deforms) with the movement of the piston 11 and seals between the inner peripheral surface of the cylinder 9 (bore portion 9A) and the outer peripheral surface 11B of the piston 11 to cause dust and dirt. Prevent foreign substances such as rainwater from entering.
[0035]
　In this case, when the annular metal member 13 is integrally formed with the large diameter fitting portion 12A, the piston boot 12 positions the metal member 13 with respect to the mold using a positioning jig (none of which is shown). By doing so, a plurality of notches 12E are formed in the large diameter fitting portion 12A. Therefore, a part of the metal member 13 integrally molded with the piston boot 12 is exposed to the outside at the position of each notch portion 12E.
[0036]
　However, each notch portion 12E is provided at a position on the bellows portion 12B side of the large diameter fitting portion 12A, and the outer peripheral end 12B2 of the extension portion 12B1 constituting the bellows portion 12B is the outer periphery of the large diameter fitting portion 12A. The diameter is expanded from the surface 12A1 to the outer peripheral side. Therefore, each notch 12E is covered by the bellows 12B in the axial direction of the piston 11. As a result, even if the muddy water is scattered toward the piston 11 while the vehicle is running, the muddy water is blocked by the bellows portion 12B of the piston boots 12 and does not reach the large diameter fitting portion 12A. As a result, the corrosion resistance of the metal member 13 can be improved by suppressing the infiltration of muddy water into each notch portion 12E formed in the large diameter fitting portion 12A and protecting the metal member 13 from the muddy water.
[0037]
　In other words, even when the structure of the mold for molding the piston boot 12 is such that each notch 12E is arranged at the position on the bellows 12B side of the large diameter fitting portion 12A, each notch 12E is adopted. It is possible to prevent muddy water from infiltrating into the water. As a result, the options for the structure of the mold for molding the piston boot 12 can be expanded, the mold structure can be simplified, and the manufacturing cost of the piston boot 12 can be reduced.
[0038]
　Further, the annular protrusion 12D provided on the inner peripheral surface 12A3 of the large-diameter fitting portion 12A of the piston boot 12 is located in the bellows portion 12B rather than the cross-sectional center P of the metal member 13 contained in the large-diameter fitting portion 12A. It is located close to each other. In this way, when the formed piston boot 12 is removed from the mold by arranging the annular protrusion 12D near the bellows portion 12B which is more easily deformed than the large diameter fitting portion 12A containing the metal member 13. , The annular protrusion 12D together with the bellows 12B can be easily removed from the mold.
[0039]
　Thus, the disc brake 2 according to the present embodiment has a piston 11 and a bore portion 9A that movably accommodates the piston 11, and an annular step portion 9E is formed on the opening end 9D side of the bore portion 9A. The piston boot 12 includes a piston boot 12 arranged between the tip end side of the piston 11 and the small diameter step portion 9E1 of the cylinder 9, and the piston boot 12 includes an annular metal member 13 and fits into the small diameter step portion 9E1. The matching annular large-diameter fitting portion 12A extends from the large-diameter fitting portion 12A to expand the diameter from the large-diameter fitting portion 12A to the outer peripheral side and bends toward the inner peripheral side from the large-diameter fitting portion 12A. The piston boot 12 has a bellows portion 12B extending from the piston and a small diameter fitting portion 12C formed at the end of the bellows portion 12B in an annular shape having a diameter smaller than that of the large diameter fitting portion 12A and fitted to the outer periphery of the piston 11. The large-diameter fitting portion 12A of the above has a notch portion 12E in which a part of the metal member 13 is exposed to the outside at a position on the bellows portion 12B side.
[0040]
　As a result, the notch 12E provided in the large-diameter fitting portion 12A can be covered by the bellows portion 12B whose diameter is expanded from the large-diameter fitting portion 12A to the outer peripheral side in the axial direction of the piston 11. As a result, by blocking the muddy water scattered toward the piston 11 when the vehicle is running by the bellows portion 12B of the piston boot 12, it is possible to suppress the muddy water from entering the notch portion 12E, and the corrosion resistance of the metal member 13 can be suppressed. Can be enhanced.
[0041]
　Moreover, the bellows portion 12B is folded inward in the radial direction from the extension portion 12B1 extending from the large diameter fitting portion 12A to the opening end 9D side of the cylinder 9 and the outer peripheral end 12B2 of the extension portion 12B1 to be a small diameter fitting portion. It is composed of an expansion / contraction portion 12B3 extending to 12C. That is, the bellows portion 12B is bent in the radial direction at a position shifted toward the open end 9D of the cylinder 9 from the large-diameter fitting portion 12A and the small-diameter fitting portion 12C in the axial direction of the piston 11. As a result, the radial dimension of the piston boot 12 can be suppressed to a small size, the layout of the cylinder 9 on which the piston boot 12 is provided on the open end 9D side can be narrowed, and the weight of the caliper 4 can be reduced.
[0042]
　In each of the above-described embodiments, a disc brake 2 having a pair of bore portions 9A and a piston 11 will be described as an example. However, the present invention is not limited to this, and for example, the present invention includes two sets of bore portions and a piston, and the facing pistons are arranged in the axial direction with the disc sandwiched between them, and the pads are pressed from both sides of the opposed disc brake. Can also be applied to.
[0043]
　As the disc brake and the piston boot based on the embodiment described above, for example, those having the following aspects can be considered.
[0044]
　In the first aspect, it has a bore portion that accommodates the piston so as to be movable in the axial direction, and has a diameter dimension larger than the inner diameter of the bore portion on the opening end side of the bore portion where the tip of the piston protrudes. A cylinder having an annular step, a piston that presses at least one of a pair of pads facing each other on both sides of the disk, and an arrangement between the tip of the piston and the step of the cylinder. The piston boot is provided with a piston boot having a bellows portion that can be expanded and contracted with the movement of the piston, and the piston boot includes an annular metal member and is fitted with an annular large-diameter fitting portion that is fitted to the step portion. The bellows portion extending from the large-diameter fitting portion, expanding the diameter from the large-diameter fitting portion to the outer peripheral side, and bending and extending toward the inner peripheral side of the large-diameter fitting portion, and the bellows portion. The end portion has a small diameter fitting portion formed in an annular shape having a diameter smaller than that of the large diameter fitting portion and fitted to the outer periphery of the piston, and the large diameter fitting portion of the piston boot has the bellows portion side. It is characterized in that a part of the metal member has a notch portion exposed to the outside at the position of.
[0045]
　As a second aspect, in the first aspect, the large-diameter fitting portion of the piston boot has an annular protrusion formed on the inner peripheral side and abutting on the outer peripheral surface of the piston, and the annular protrusion has an annular protrusion. Is characterized in that it is formed at a position closer to the bellows portion than the cross-sectional center of the metal member in the axial direction of the piston.
[0046]
　The third aspect is characterized in that, in the first or second aspect, the notch portions are formed at a plurality of positions in the circumferential direction of the large-diameter fitting portion.
[0047]
　As a fourth aspect, a step portion formed on the opening side of a cylinder having a bore portion provided in the caliper of the disc brake and a tip end side of a piston housed in the bore portion so as to be movable in the axial direction. A piston boot that is arranged between and has a bellows portion that can be expanded and contracted with the movement of the piston, and the piston boot is an annular large-diameter fitting that contains an annular metal member and fits into the step portion. The joint portion, the bellows portion extending from the large-diameter fitting portion, expanding the diameter from the large-diameter fitting portion to the outer peripheral side, and bending and extending toward the inner peripheral side of the large-diameter fitting portion, and the said. The large-diameter fitting portion of the piston boot has a small-diameter fitting portion formed at the end of the bellows portion in an annular shape having a diameter smaller than that of the large-diameter fitting portion and fitted to the outer periphery of the piston. It is characterized in that a part of the metal member has a notch portion exposed to the outside at a position on the bellows side.
[0048]
　As a fifth aspect, in the fourth aspect, the large-diameter fitting portion of the piston boot has an annular protrusion formed on the inner peripheral side and abutting on the outer peripheral surface of the piston, and the annular protrusion has an annular protrusion. Is characterized in that it is formed at a position closer to the bellows portion than the cross-sectional center of the metal member in the axial direction of the piston.
[0049]
　A sixth aspect is characterized in that, in the fourth or fifth aspect, the notch portions are formed at a plurality of positions in the circumferential direction of the large-diameter fitting portion.
[0050]
　The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.
[0051]
　The present application claims priority based on Japanese Patent Application No. 2018-237272 filed on December 19, 2018. The entire disclosure, including the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-237272 filed December 19, 2018, is incorporated herein by reference in its entirety.
Code description
[0052]
　1 Disc 8 Friction pad (pad) 9 Cylinder 9A Bore part 9D Open end 9E1 Small diameter step part (step part) 11 Piston 11B Outer peripheral surface 12 Piston boot 12A Large diameter fitting part (fitting part) 12B Bellows part 12C Small diameter fitting Part 12E Notch 13 Metal member
The scope of the claims
[Claim 1]
　The disc brake has
　a piston that presses at least one of a pair of pads facing each other on both sides of the disc, and
　a bottomed bore portion that accommodates the piston so as to be movable in the axial direction. Between a cylinder in which an annular step portion having a diameter larger than the inner diameter of the bore portion is formed on the opening end side of the bore portion with a protruding tip, and between the tip end side of the
　piston and the step portion of the cylinder. The
　piston boot is provided with a piston boot having a bellows portion that can be expanded and contracted with the movement of the piston, and the piston boot includes an annular metal member and is fitted to the step portion in an annular large diameter. The bellows portion, the bellows portion extending from the large-diameter fitting portion, expanding the diameter from the large-diameter fitting portion to the outer peripheral side, and bending and extending toward the inner peripheral side of the large-diameter fitting portion, and the bellows. The end of the portion has a small-diameter fitting portion formed in an annular shape having a diameter smaller than that of the large-diameter fitting portion and fitted to the outer periphery of the piston, and the
　large- diameter fitting portion of the piston boot has the bellows. A disc brake characterized by having a notch in which a part of the metal member is exposed to the outside at a position on the portion side.
[Claim 2]
　In the disc brake according to claim 1, the
　large-diameter fitting portion of the piston boot has an annular protrusion formed on the inner peripheral side and abutting on the outer peripheral surface of the piston, and the annular protrusion has the
　annular protrusion. A disc brake formed at a position closer to the bellows portion than the center of the cross section of the metal member in the axial direction of the piston.
[Claim 3]
　In the disc brake according to claim 1 or 2, the
　notch portions are formed at a plurality of locations in the circumferential direction of the large diameter fitting portion.
[Claim 4]
　The piston boot
　is a piston boot having a step portion formed on the open end side of a cylinder having a bore portion provided in a caliper of a disc brake and a piston housed in the bore portion so as to be movable in the axial direction. The
　piston boot also has a bellows portion that can be expanded and contracted with the movement of the piston, and the
　piston boot contains an annular metal member. An annular large-diameter fitting portion that fits into the step portion, and an annular large-diameter fitting portion that extends from the large-diameter fitting portion to expand the diameter from the large-diameter fitting portion to the outer peripheral side and is inside the large-diameter fitting portion. It has a bellows portion that bends and extends to the circumferential side, and a small diameter fitting portion that is formed in an annular shape having a smaller diameter than the large diameter fitting portion at the end of the bellows portion and that fits on the outer periphery of the piston. The
　piston boot is characterized in that the large-diameter fitting portion of the piston boot has a notch portion in which a part of the metal member is exposed to the outside at a position on the bellows portion side.
[Claim 5]
　In the piston boot according to claim 4, the
　large-diameter fitting portion of the piston boot has an annular protrusion formed on the inner peripheral side and abutting on the outer peripheral surface of the piston, and the
　annular protrusion is the said. A piston boot formed at a position closer to the bellows portion than the center of the cross section of the metal member in the axial direction of the piston.
[Claim 6]
　The piston boot according to claim 4 or 5,
　wherein the notches are formed at a plurality of positions in the circumferential direction of the large-diameter fitting portion.