JP2010001956A - Disk brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a split type piston 19a (19b) formed of a piston body 21a (21b) and a presser member 23a (23b) and structured by arranging the presser member 23a (23b) in a tip of the piston body 21a (21b) freely to swing. <P>SOLUTION: An inner diameter side lock part 38 of a dust boot 31a (31b) is arranged between a small diameter stage part 36 formed in an outer peripheral surface of a base end of a presser member 23a (23b) and an inner peripheral surface of a cylindrical part 35 formed in a tip of a piston body 21a (21b) so that both the peripheral surfaces elastically abut on each other over the whole circumference. With this structure, separation of the piston body 21a (21b) and the presser member 23a (23b) from each other is prevented. Since other member is not required to prevent such a separation, costs can be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement in a disc brake used for braking an automobile. Specifically, the piston is a split type composed of a piston main body and a pressing member, and the cost of the structure in which the pressing member is arranged to be swingable at the tip of the piston main body is reduced.

  Disc brakes are widely used to brake automobiles. At the time of braking by the disc brake, a pair of pads arranged on both sides in the axial direction of the rotor rotating together with the wheels are pressed against both side surfaces of the rotor by the piston. Conventionally, various types of disc brakes are known. FIG. 4 shows a first example of the conventional structure of the opposed piston type disc brake among such various structures.

  As shown in FIG. 4, the opposed piston type disc brake 1 is provided with a caliper 5 including an outer body portion 3 and an inner body portion 4 at a position sandwiching a rotor 2 that rotates together with wheels. Further, an outer cylinder and an inner cylinder are provided in each of the body parts 3 and 4 with their respective openings facing each other through the rotor 2. The outer piston and the inner piston are fitted in the outer cylinder and the inner cylinder in a liquid-tight manner and capable of displacement in the axial direction of the rotor 2. Further, an outer pad is supported on the outer body portion 3 and an inner pad is supported on the inner body portion 4 so as to be capable of displacement in the axial direction of the rotor 2. During braking, pressure oil is fed into the outer cylinder and the inner cylinder, and the outer pad and the inner pad are pressed against both the inner and outer side surfaces of the rotor 2 by the outer piston and the inner piston.

  5 to 8 show a more specific structure of the opposed piston type disc brake described in Patent Document 1. FIG. The disc brake 1a of the second example of the conventional structure shown in FIGS. 5 to 8 also includes a caliper 5a arranged in a state straddling the rotor 2. The caliper 5a is integrally made of an aluminum alloy material, and is arranged on both sides of the rotor 2 in the axial direction (front and back directions in FIGS. 5 and 7, the vertical direction in FIG. 6, and the horizontal direction in FIG. 8). The outer body portion 3a and the inner body portion 4a, and a pair of connecting portions 6 and 6 that connect both ends of the body portions 3a and 4a in the circumferential direction (the left-right direction in FIGS. 5 to 7 and the front and back direction in FIG. 8) Is provided. In the case of the illustrated example, a total of six outer and inner cylinders 7 and 7 (8 and 8) are provided in each of the body parts 3a and 4a, and the cylinders 7 and 7 ( 8 and 8) are fitted with outer and inner pistons 9 and 9 (10 and 10), respectively. Then, by the pistons 9 and 9 (10 and 10), the outer and inner pads 11 and 12 supported by the body parts 3a and 4a are pressed against the rotor 2 with the rotor 2 interposed therebetween. It is configured to perform braking.

  In addition, a pair of torque receiving pins between the radially outer ends of the portions located between the connecting portions 6 and 6 at the circumferential intermediate portion between the outer body portion 3a and the inner body portion 4a. 13, 13 and one intermediate coupling pin 14 are provided in a state of being spanned between the body parts 3a, 4a. Among these pins 13, 14, the torque receiving pins 13, 13 have a diameter larger than the outer peripheral edge of the rotor 2 at a position sandwiching the pressure plates 15, 15 of the outer and inner pads 11, 12 from both sides in the circumferential direction. It is provided in the direction outside part. Further, the intermediate coupling pin 14 is provided in a portion between the torque receiving pins 13 and 13 on the outer side in the radial direction from the pads 11 and 12. Each of these pins 13 and 14 serves to prevent the distance between the outer body portion 3a and the inner body portion 4a from being deformed in a direction in which it is expanded by a reaction force during pressurization for braking.

  The torque receiving pins 13 and 13 are in contact with or in close proximity to the circumferential edges of the pressure plates 15 and 15 constituting the outer and inner pads 11 and 12, respectively. On the other hand, a pad clip 16 is provided between the remaining intermediate coupling pin 14 and the radially outer peripheral edges of the pressure plates 15 and 15 of the pads 11 and 12, and the pressure plates 15 and 15 are attached to the pressure plates 15 and 15. , Elastic force directed radially inward and elastic force in directions away from each other are applied.

  Further, two locking pins 17 and 17 are provided for each of the body parts 3a and 4a on the radially inward portion of the outer body part 3a and the inner body part 4a. Provided. These locking pins 17 and 17 are fixed to the positions in the vicinity of both ends in the circumferential direction at the radially inner ends of the body parts 3a and 4a, respectively. In this state, the radially inner end edges of the pressure plates 15, 15 of the pads 11, 12 are pressed against the partial outer peripheral surfaces of the locking pins 17, 17 based on the elasticity of the pad clip 16. The locking pins 17 and 17 prevent the pads 11 and 12 from slipping out of the caliper 5a inward in the radial direction of the rotor 2 and make the pads 11 and 12 rattle when not braked. To prevent.

  At the time of braking by the opposed piston type disc brake configured as described above, pressure oil is fed into each of the outer cylinders 7 and 7 and the inner cylinders 8 and 8. Then, the outer pistons 9 and 9 and the inner pistons 10 and 10 are pushed out to press the outer and inner pads 11 and 12 against both side surfaces of the rotor 2. As a result, braking is performed by friction between the linings 18 and 18 constituting both the pads 11 and 12 and both side surfaces of the rotor 2.

  The above-described outer and inner pistons 9 and 10 are usually integrated, and the tip surfaces of the pistons 9 and 10 are often brought into direct contact with the outer and inner pads 11 and 12 in many cases. On the other hand, Patent Document 2 describes a structure in which a piston is constituted by a heat insulating material pressing member and a piston body, and the pressing member is disposed between the piston body and a pad. In addition, the frictional heat at the time of braking is hardly transmitted to the piston body, so that the rubber seal is hardly deteriorated and the vapor lock of the hydraulic oil is hardly generated. Also, in Patent Documents 3 to 5, when the pad is inclined with respect to the pressing direction of the piston due to uneven wear of the pad lining or deformation of the caliper due to the difference in hydraulic pressure of the pressure oil introduced into each cylinder, etc. However, a structure that equalizes the contact pressure between the piston and the pad is described. FIG. 9 shows the structure described in Patent Document 3 among them.

  In the case of the structure shown in FIG. 9, the piston 19 includes a piston main body 21 fitted in the cylinder 20, and the piston main body 21 between the piston main body 21 and the inner side (right side in FIG. 9) pad 22. 21 and a pressing member 23 arranged to be swingable with respect to 21. The structure shown in FIG. 9 is different from the structure shown in FIGS. 3 to 8 described above, and shows a structure related to a floating caliper type disc brake. Since the basic structure and operation of this floating caliper type disc brake are well known in the art and are not related to the gist of the present invention, detailed description thereof will be omitted.

  In order to arrange the pressing member 23 so as to be swingable with respect to the piston main body 21, the base end surface (right end surface in FIG. 9) of the pressing member 23 is formed into a convex spherical surface, and the distal end surface (FIG. 9) of the piston main body 21. Left end surface) are formed as concave spherical surfaces, and these spherical surfaces are engaged with each other. In the case of the structure shown in FIG. 9, the piston main body 21 is made hollow, the front end surface central portion of the piston main body 21, the base end surface central portion of the pressing member 23, and the axial direction of the pressing member 23. Ventilation holes 24a, 24b, and 24c are provided in the intermediate portion, respectively, and the internal space 25 of the piston body 21 is communicated with the outside air. The cooling efficiency of the piston 19 is increased.

  In the case of the structure shown in FIG. 9, a cylindrical portion 26 that protrudes toward the pad 22 is formed on the outer diameter side portion of the front end surface of the piston main body 21. Then, by engaging the retaining ring 28 locked to the locking groove 27 formed on the inner peripheral surface of the cylindrical portion 26 and the flange portion 29 formed protruding from the outer peripheral surface of the proximal end portion of the pressing member 23, This pressing member 23 is prevented from coming out of the piston main body 21. Further, a dust boot 31 is disposed between the outer peripheral surface of the cylindrical portion 26 and the opening of the cylinder 20 of the caliper 30, and the piston 19 and the piston 19 and the Foreign matter is prevented from entering the fitting portion with the cylinder 20 from the outside. For this reason, in the case of the structure shown in FIG. 9, a concave groove 32 is formed on the outer peripheral surface of the cylindrical portion 26 of the pressing member 23, and the inner peripheral edge portion of the dust boot 31 is locked in the concave groove 32. ing.

  In the case of the structure shown in FIG. 9 described above, since the pressing member 23 and the piston main body 21 are engaged with each other by the spherical portion, the pressing member 23 can swing with respect to the piston main body 21. As a result, as described above, even when the pad 22 is inclined with respect to the pressing direction of the piston 19, the contact pressure between the pressing member 23 and the pad 22 is equalized, and the pressing of the pad 22 by the piston 19 is performed. Can be done properly. However, in the case of the structure shown in FIG. 9, a retaining ring 28 is provided to prevent the pressing member 23 from coming out of the piston body 21. For this reason, it is inevitable that the number of parts increases and the manufacturing cost increases. In Patent Documents 4 and 5, there is no description regarding the retaining of the pressing member with respect to the piston body. In the case of the structure described in Patent Document 4, the tip surface of the pressing member is formed in a circular arc shape and a concave portion having a circular arc shape is also formed on the pad side, so that special processing is required for the pad. After all, the manufacturing cost becomes high.

JP 2005-121174 A JP-A-9-49537 Japanese Patent Laid-Open No. 11-30258 Japanese Patent Laid-Open No. 8-232991 JP-A-8-14280

  In view of the circumstances as described above, the present invention realizes a structure in which the piston is a split type composed of a piston main body and a pressing member, and the pressing member is disposed at the tip of the piston main body so as to be swingable. Invented as much as possible.

The disc brake of the present invention includes a pair of pads, a piston, a caliper, and a dust boot.
Both of these pads are provided with a rotor rotating together with the wheels.
The piston presses at least one of these pads against the side surface of the rotor.
The caliper includes a cylinder for fitting the piston.
The dust boot is made of an elastic material and is provided between the outer peripheral surface of the piston and the opening of the cylinder, and allows the piston and the cylinder to be fitted while allowing displacement of the piston with respect to the cylinder. This prevents foreign matter from entering the part.

In particular, in the disc brake of the present invention, the piston is disposed between the piston body fitted in the cylinder and the piston body and the pad so as to be swingable with respect to the piston body. And a pressing member made of a material having higher heat insulation than the piston body.
In addition, the inside of the dust boot is between a partial peripheral surface of the proximal end portion of the pressing member and a partial peripheral surface of the distal end portion of the piston body, which are opposed to each other over the entire circumference in the radial direction. The peripheral portion is disposed in a state where the peripheral portion is elastically contacted with each of the peripheral surfaces over the entire circumference. The piston main body and the pressing member are prevented from being separated.

  As a specific structure of the present invention as described above, for example, as in the invention described in claim 2, a cylindrical portion is provided at the distal end portion of the piston body, and a proximal end portion of the pressing member is provided over the entire circumference. And projecting to cover. The inner peripheral edge of the dust boot is elastically brought into contact with both peripheral surfaces over the entire circumference between the outer peripheral surface of the proximal end portion of the pressing member and the inner peripheral surface of the cylindrical portion. Arrange in the state of letting.

  Further, when the invention described in claim 2 is carried out, preferably, as in the invention described in claim 3, a small-diameter step portion having a smaller diameter than the intermediate portion is provided on the outer peripheral surface of the base end portion of the pressing member. A flange portion protruding toward the inner diameter side is formed at the tip of the cylindrical portion of the piston body. And the inner peripheral edge part of the said dust boot is arrange | positioned between the said small diameter step part and the part nearer to the base end rather than the said collar part among the internal peripheral surfaces of the said cylindrical part.

  Furthermore, when the invention described in claim 2 or claim 3 is carried out, the portion of the piston main body excluding the cylindrical portion is preferably solid as in the invention described in claim 4.

As described above, in the case of the disc brake of the present invention, the pressing member made of a material having higher heat insulation than the piston main body is disposed between the pad and the piston main body. The frictional heat generated by is difficult to be transmitted to the piston body. For this reason, it is hard to produce the bad influence by heat, such as the thermal deterioration of a piston seal, and the vapor lock of hydraulic oil.
Further, since the pressing member is disposed so as to be swingable with respect to the piston body, even if the pad is inclined, the contact pressure between the pressing member and the pad can be made uniform, and the pressing of the pad by the piston can be performed. This can be done appropriately regardless of the inclination of the pad.
Further, since the pressing member and the piston main body elastically contact the inner peripheral edge of the dust boot to prevent separation from each other, another member is prepared to prevent this separation. This is unnecessary, and an increase in manufacturing cost due to an increase in the number of parts can be prevented.

  Further, in the case of the invention described in claim 3, the inner peripheral edge of the dust boot is prevented from inadvertently coming out from between the pressing member and the piston body, so that the separation of these two members is more reliably prevented. I can plan.

  Furthermore, in the case of the invention described in claim 4, since the piston body is solid, the volume of the space sealed by the dust boot can be reduced. For this reason, the air present in the sealed space expands due to a temperature rise during braking, and the pressing member is displaced, or due to the expansion of the dust boot, a part of the dust boot comes into contact with the pad. It is possible to prevent the dust boot from being damaged.

  1 and 2 show an example of an embodiment of the present invention. The feature of the present invention is that the structure of the portion for preventing separation between the piston bodies 21a, 21b and the pressing members 23a, 23b is devised in order to reduce the manufacturing cost. This example shows a case where the present invention is applied to an opposed piston type disc brake. Accordingly, among the structures other than the features of this example, the basic structure and operation of the opposed piston type disc brake are the same as those of the conventional structure shown in FIGS. In the following, the characteristic part of this example will be mainly described.

  In the case of this example, two types of pistons 19a and 19b having different diameters are fitted into the respective cylinders 20a and 20b provided on the caliper 5b. In the case of this example, although a part of the illustration is omitted, the present invention is applied to a so-called 6-pot opposed piston type disc brake in which each of the pistons 19a and 19b and the cylinders 20a and 20b is provided at three locations on one side. The structure which applied is shown. Of these, the pistons 19a, 19a having a large diameter are arranged on the delivery side (left side in FIG. 1) of the rotor 2 so as to face each other. Further, the pistons 19b, 19b having a small diameter are arranged in the state where they face each other on the turning-in side (right side in FIG. 1) of the rotor 2. Each of such pistons 19a and 19b is composed of a combination of piston bodies 21a and 21b and pressing members 23a and 23b.

  Of these, the piston bodies 21a and 21b are made of metal such as an aluminum alloy, and are fitted into the cylinders 20a and 20b, respectively. The pressing members 23a and 23b are made of, for example, a synthetic resin, and are disposed between the piston main bodies 21a and 21b and the pads 22a and 22a so as to be swingable with respect to the piston main bodies 21a and 21b. Has been. In addition, as synthetic resin which comprises each said press member 23a, 23b, what mixed heat insulating fibers, such as ceramic fiber, glass fiber, and carbon fiber, is mentioned to synthetic resin, such as polyacetal, phenol, and polyamideimide, for example. . In addition to the synthetic resin, for example, ceramics may be used as the pressing members 23a and 23b. In short, it is sufficient to use a material that can secure sufficient strength and rigidity and has a lower thermal conductivity (higher heat insulation) than the piston bodies 21a and 21b.

  In the case of this example, in order to allow the pressing members 23a and 23b to swing with respect to the piston bodies 21a and 21b, the base end surfaces (right end surfaces in FIG. 2) of the pressing members 23a and 23b The front end surfaces (left end surfaces in FIG. 2) of the piston bodies 21a and 21b are spherically engaged. That is, the concave surface portion 33 that is a concave spherical surface is formed on the base end surface of each of the pressing members 23a and 23b. On the other hand, a convex surface portion 34 having a convex spherical surface having the same or slightly smaller radius of curvature as the concave surface portion 33 is formed on the tip surface of each of the pistons 21a and 21b. It should be noted that these irregularities can be reversed. That is, the proximal end surface of the pressing member can be a convex surface portion, and the distal end surface of the piston body can be a concave surface portion.

  A cylindrical portion 35 protruding toward the pad 22a is formed at the radially outer end portion of the tip surface of each of the piston main bodies 21a and 21b. Further, a small diameter step portion 36 having a smaller diameter than the intermediate portion is formed on the outer peripheral surface of the base end portion of each of the pressing members 23a and 23b. And in the state which combined each said piston main body 21a, 21b and each said press member 23a, 23b, the internal peripheral surface of the said cylindrical part 35 and the outer peripheral surface of the said small diameter step part 36 are made to oppose to radial direction. . Further, a radial gap 37 is provided between the two peripheral surfaces.

  In the case of this example, the inside of dust boots 31a and 31b made of an elastic material such as rubber for preventing foreign matter from entering the gaps 37 between the pistons 19a and 19b and the cylinders 20a and 20b. The periphery is arranged. That is, an inner diameter side locking portion 38 having a thickness larger than the radial width of the gap 37 is provided on the inner peripheral edge of each of the dust boots 31a and 31b over the entire circumference in a free state. Yes. And this inner diameter side latching | locking part 38 is arrange | positioned in the said clearance gap 37 in the state compressed elastically. As a result, the inner diameter side locking portion 38 elastically contacts the inner peripheral surface of the cylindrical portion 35 and the outer peripheral surface of the small diameter step portion 36 over the entire circumference.

  In the case of this example, a flange 39 protruding to the inner diameter side is formed at the tip of the cylindrical portion 35. And the inner diameter side latching | locking part 38 of each said dust boot 31a, 31b is arrange | positioned in the said gap 37 in the part nearer to the base end rather than the said collar part 39. FIG. In this state, the inner peripheral edge of the inner diameter side locking portion 38 and the outer peripheral surface of the small diameter step portion 36 formed at the proximal end portions of the pressing members 23a and 23b are frictionally engaged. Thereby, the separation of the piston main bodies 21a and 21b and the pressing members 23a and 23b is prevented.

  Further, the dust boots 31a and 31b are provided on the outer peripheral edge, and are part of the caliper 5b and are engaged with locking grooves 40 and 40 formed around the cylinders 20a and 20b. The locking portion 41 and the inner diameter side locking portion 38 are made continuous by a bellows portion 42. When the pistons 19a and 19b are displaced in the cylinders 20a and 20b, the bellows portion 42 is elastically deformed, so that the inner diameter side locking portions 38 are axially connected to the pistons 19a and 19b. Follow the displacement. As a result, the dust boots 31a and 31b allow the pistons 19a and 19b to be displaced with respect to the cylinders 20a and 20b, while fitting portions between the pistons 19a and 19b and the cylinders 20a and 20b. Prevents foreign matter from entering.

  In the case of this example, the continuous portions 43a, 43b of the both end portions of the bellows portion 42 constituting the dust boots 31a, 31b and the both inner diameter side and outer diameter side locking portions 38, 41 are as described above. The shape is along the opening of each cylinder 20a, 20b. That is, the continuous portion 43a on the inner diameter side extends from the inner diameter side locking portion 38 to the distal end surface of the cylindrical portion 35 of each piston main body 21a, 21b and the inner peripheral surface of the opening portion of each cylinder 20a, 20b. The shape is along each surface. Further, the outer diameter side continuous portion 43b is shaped so as to extend along the wall surface 44 around the opening of each of the cylinders 20a and 20b from the outer diameter side locking portion 41. Thereby, in this example, the volume of the space sealed by the dust boots 31a and 31b is minimized.

  In the case of this example, portions of the piston bodies 21a and 21b other than the cylindrical portion 35 are solid. Therefore, the space sealed by the dust boots 31a and 31b can be made smaller. In the case of this example, the pressing members 23a and 23b are also solid. Thus, by making each piston main body 21a, 21b and each pressing member 23a, 23b solid, the stress which acts on these each member 21a, 21b, 23a, 23b at the time of braking can be reduced.

  When assembling the structure of the present example as described above, for example, the dust boots 31a and 31b are disposed closer to the base end side than the flange portion 39 on the inner peripheral surface of the cylindrical portion 35 of each piston main body 21a and 21b. The inner diameter side locking portion 38 is fitted inside. In this state, the small diameter step portion 36 of each pressing member 23a, 23b is pushed into the cylindrical portion 35. At this time, the inner peripheral surface of the inner diameter side locking portion 38 elastically contacts the small diameter step portion 36, and the outer peripheral surface of the inner diameter side locking portion 38 elastically contacts the inner peripheral surface of the cylindrical portion 35. Abut. In this state, the piston bodies 21a and 21b are fitted into the cylinders 20a and 20b, and the outer diameter side locking portions 41 of the dust boots 31a and 31b are locked to the locking grooves 40. To do.

  In the case of this example as described above, the pressing members 23a and 23b made of a material having higher heat insulation than the piston bodies 21a and 21b are disposed between the pads 22a and 22a and the piston bodies 21a and 21b. is doing. For this reason, the frictional heat generated by the friction between the pad and the rotor during braking is not easily transmitted to the piston bodies 21a and 21b. For this reason, it is hard to produce the bad influence by heat, such as the thermal deterioration of a piston seal, and the vapor lock of hydraulic oil.

  The pressing members 23a and 23b are arranged so as to be swingable with respect to the piston bodies 21a and 21b. Therefore, even if the pads 22a and 22a are inclined, the pressing members 23a and 23b The contact pressure with the pads 22a and 22a can be made uniform. Then, the respective pads 22a and 22a can be appropriately pressed by the pistons 19a and 19b regardless of the inclination of the pads 22a and 22a. In the case of this example, the inner diameter side locking portions 38 of the dust boots 31a and 31b are provided between the small diameter step portions 36 of the pressing members 23a and 23b and the cylindrical portions 35 of the piston bodies 21a and 21b. Is arranged. Since the inner diameter side locking portion 38 is made of an elastic material, as described above, the pressing members 23a and 23b do not hinder the rocking of the piston main bodies 21a and 21b.

  In the case of this example, the pressing members 23a, 23b and the piston bodies 21a, 21b are separated from each other by elastically contacting the inner diameter side engaging portions 38 of the dust boots 31a, 31b. Since the prevention is intended, it is not necessary to prepare another member for preventing the separation. As a result, compared with the structure shown in FIG. 9, the number of parts can be reduced and the manufacturing cost can be reduced. In the case of this example, the inner diameter side engaging portions 38 of the dust boots 31a and 31b are located deeper in the gap 37 than the flange 39 formed at the tip of the cylindrical portion 35 of the piston bodies 21a and 21b. It arrange | positions to the side (base end side of piston main body 21a, 21b). For this reason, even when the inner diameter side locking portion 38 tends to come out of the gap 37, the inner diameter side locking portion 38 is connected to the flange portion 39 and the step portion 45 of the small diameter step portion 36. Engage. The inner diameter side locking portion 38 is prevented from inadvertently coming out of the gap 37. As a result, it is possible to more reliably prevent the piston bodies 21a and 21b and the pressing members 23a and 23b from being separated. In addition, as shown in FIG. 3, if the collar part 46 which protrudes to an outer-diameter side is provided in the outer peripheral surface of the base end part of the press member 23a (23b), even before the assembly of each component member is completed. Further, the pressing members 23a (23b) can be more reliably prevented from inadvertently coming out of the piston body 21a (21b).

  Further, in the case of this example, the piston bodies 21a and 21b are made solid, and the continuous portions 43a and 43b of the dust boots 31a and 31b are arranged along the shapes of the openings of the cylinders 20a and 20b. It has a shape. For this reason, the volume of the space sealed by the dust boots 31a and 31b can be minimized. In the case of this example, the inner diameter side engaging portions 38 of the dust boots 31a and 31b are connected to the inner peripheral surface of the cylindrical portion 35 of the piston bodies 21a and 21b and the small diameter step portions 36 of the pressing members 23a and 23b. Therefore, the back sides of the cylinders 20a and 20b are sealed by the dust boots 31a and 31b. Therefore, when the air in the sealed space expands due to a temperature rise, the pressing members 23a and 23b are pushed out according to the expansion amount. In spite of non-braking, the contact surface pressure with respect to each pad 22a, 22a becomes higher than a predetermined value, and so-called dragging occurs in which the linings 18, 18 of the pads 22a, 22a rub against the side surface of the rotor 2 can occur. There is sex. Further, the dust boots 31a and 31b may expand, and a part of the dust boots 31a and 31b may come into contact with the pads 22a and 22a, and the dust boots 31a and 31b may be damaged.

  On the other hand, in the case of this example, as described above, since the space sealed by the dust boots 31a and 31b is made small, the amount of air expanding due to the temperature rise is reduced, and the air accompanying the temperature rise is reduced. The amount of expansion can be reduced. As a result, the displacement of the pressing members 23a and 23b and the expansion of the dust boots 31a and 31b can be suppressed, and the contact surface pressure between the pressing members 23a and 23b and the pads 22a and 22a is unnecessary. It is possible to prevent the dust boots 31a and 31b from being damaged.

  Note that, as in the conventional structure shown in FIG. 9, it is conceivable that the piston body is hollow and the internal space of the piston body communicates with the outside air. For this purpose, a vent hole is provided in the pressing member. It is necessary to form, and the manufacturing cost of this pressing member increases. Moreover, it is disadvantageous from the viewpoint of ensuring the strength and rigidity of the pressing member. On the other hand, in the case of this example, the pressing members 23a and 23b are solid, and the manufacturing cost of the pressing members 23a and 23b is reduced and the strength and rigidity of the pressing members 23a and 23b are secured. The piston main bodies 21a and 21b are solid so as to prevent inconveniences such as breakage of the dust boots 31a and 31b due to air expansion.

In the above-described embodiment, a so-called 6-pot opposed piston type disc brake having three pistons and cylinders on one side has been described. However, the present invention can be applied regardless of the number of pistons and cylinders. It is.
In the above-described embodiment, the piston body is formed with the cylindrical portion and the pressing member is formed with the small diameter step portion, and the inner diameter side locking portion of the dust boot is disposed between the cylindrical portion and the small diameter step portion. This relationship can be reversed. That is, a small diameter step portion is formed on the outer peripheral surface of the distal end portion of the piston body, and a cylindrical portion is formed so as to cover the small diameter step portion of the piston body from the base end surface of the pressing member. The inner diameter side locking portion of the dust boot can be arranged between the two.
Furthermore, in the above-described embodiment, the structure in which the present invention is applied to the opposed piston type disc brake has been described. However, the present invention is also applicable to the floating caliper type disc brake as shown in FIG. Applicable.

The partial cross-sectional view which shows the 1st example of embodiment of this invention. The A section enlarged view of FIG. The elements on larger scale which show another example of the structure of the part which arrange | positions the inner diameter side latching | locking part of a dust boot. The perspective view which shows the 1st example of the disk brake conventionally known. The orthographic projection figure seen from the inner side which shows the 2nd example. The figure seen from the radial direction outer side which is the upper part of FIG. BB sectional drawing of FIG. CC sectional drawing of FIG. Sectional drawing which shows the 3rd example of the disk brake conventionally known.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Disc brake 2 Rotor 3, 3a Outer body part 4, 4a Inner body part 5, 5a, 5b Caliper 6 Connection part 7 Outer cylinder 8 Inner cylinder 9 Outer piston 10 Inner piston 11 Outer pad 12 Inner pad 13 Torque receiving pin 14 Intermediate Connecting pin 15 Pressure plate 16 Pad clip 17 Locking pin 18 Lining 19, 19a, 19b Piston 20, 20a, 20b Cylinder 21, 21a, 21b Piston body 22, 22a Pad 23, 23a, 23b Press member 24a, 24b, 24c Through Pore 25 Internal space 26 Cylindrical portion 27 Locking groove 28 Retaining ring 29 Hook 30 Caliper 31, 31a, 31b Dust boot 32 Recessed groove 33 Concave portion 34 Convex portion 35 Cylindrical portion 36 Small diameter step portion 37 Gap 8 the inner diameter side locking portion 39 flange portion 40 engaging groove 41 outer diameter side locking portions 42 bellows portion 43a, 43b continuous portion 44 wall 45 stepped portion 46 flange portion

Claims (4)

A pair of pads provided across a rotor that rotates with the wheel; a piston that presses at least one of these pads against the side surface of the rotor; and a caliper that includes a cylinder in which the piston is fitted; Elasticity that is provided between the outer peripheral surface of the piston and the opening of the cylinder and prevents foreign matter from entering the fitting portion between the piston and the cylinder while allowing displacement of the piston with respect to the cylinder. In disc brakes with dust boots made of wood,
A material having higher heat insulation than the piston body, wherein the piston is disposed between the piston body fitted in the cylinder and the piston body and the pad so as to be swingable with respect to the piston body. Consisting of a pressing member made of
An inner peripheral edge portion of the dust boot between a partial peripheral surface of the proximal end portion of the pressing member and a partial peripheral surface of the distal end portion of the piston body, which are opposed to each other over the entire circumference in the radial direction. The disc brake is characterized in that the piston body and the pressing member are prevented from being separated from each other by arranging them in a state where they are elastically abutted on both of the circumferential surfaces.   A cylindrical portion is formed at the distal end portion of the piston body so as to cover the base end portion of the pressing member over the entire circumference, and the outer peripheral surface of the base end portion of the pressing member and the inner periphery of the cylindrical portion The disc brake according to claim 1, wherein the inner peripheral edge portion of the dust boot is disposed in a state in which the dust boot is in elastic contact with both peripheral surfaces over the entire circumference.   A small diameter step portion having a smaller diameter than the intermediate portion is formed on the outer peripheral surface of the proximal end portion of the pressing member, and a flange portion protruding to the inner diameter side is formed on the distal end portion of the cylindrical portion of the piston body. The disc brake according to claim 2, wherein an inner peripheral edge portion is disposed between the small-diameter step portion and a portion closer to the proximal end than the flange portion of the inner peripheral surface of the cylindrical portion.   The disc brake according to claim 2 or 3, wherein a portion of the piston body excluding the cylindrical portion is solid.

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