JP2006200579A - Braking device with hydraulic operated piston - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking device with a hydraulic operated piston for improving the feeling characteristic of a brake at the beginning of braking and securing constant seal adjusting performance while maintaining roll-back operation. <P>SOLUTION: The braking device with the hydraulic operated piston comprises the piston 27 having a seal 41 on the outer periphery and internally inserted into a cylinder hole 25 formed in a brake housing. The piston 27 is operated by the hydraulic pressure of a hydraulic pressure chamber 29 formed by one end of the piston 27 and the brake housing to thrust a friction member against a rotor for braking operation. An outer peripheral portion 41a of the seal 41 has slide contact with the cylinder hole 25 and an inner peripheral portion 41b is housed in a seal groove 43 formed in the piston 27. On an outward portion of a counter rotor side wall face 43a of the seal groove 43, a boss 27A is provided which abuts on an outward portion of a side face 41A on the counter rotor side of the seal 41. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  According to the present invention, a piston having a seal on the outer periphery is inserted into a cylinder hole formed in a brake housing, and the piston is operated by a hydraulic pressure of a hydraulic chamber formed by one end of the piston and the brake housing to cause friction. The present invention relates to a braking device including a hydraulically operated piston that presses a member against a rotor to brake the member.

  2. Description of the Related Art Conventionally, in a braking device including a hydraulically operated piston in which a piston having a seal on the outer periphery is inserted into a cylinder hole, a seal is housed in a seal groove formed on the outer periphery of the piston. (For example, refer to Patent Document 1). FIG. 6 (a) is a sectional view of a disc brake having such a conventional hydraulically operated piston, and FIGS. 6 (b) and 6 (c) are enlarged operation explanatory views before and after the braking action of the seal. is there.

  As shown in FIG. 6 (a), brake pads 3, 3 are arranged opposite to each other on the left and right sides of the rotor 1, and these brake pads 3, 3 are pistons 9 inserted in cylinder holes 7 formed in the caliper body 5. The piston 9 is configured to press against the rotor 1 to perform a braking action. The operation of the piston 9 is performed by the hydraulic chamber 11 in the cylinder hole 7 formed by one end of the piston 9 and the caliper body 5. This is done by introducing hydraulic pressure into

  As shown in FIG. 6B, a seal groove 13 having a U-shaped cross section is formed on the outer peripheral surface of the piston 9, and a seal 15 is accommodated in the seal groove 13. During non-braking before the piston 9 is actuated, the seal 15 has a substantially parallelogram-shaped cross section in which the inner peripheral surface 15b is biased toward the rotor side (hydraulic pressure chamber) of the seal groove 13 and the outer peripheral surface 15a is biased toward the rotor. A gap A is formed between a rotor-side side surface 15 d of the seal 15 and a rotor-side wall surface 13 d of the seal groove 13. At the time of braking when the hydraulic pressure is introduced into the hydraulic chamber 11, as shown in FIG. 6C, the vicinity of the inner peripheral portion of the seal 15 is pressed against the rotor-side wall surface 13 d side of the seal groove 13, As a result, the gap A disappears, and the gap B is formed between the side surface 15c of the seal 15 on the opposite side of the rotor and the wall surface 13c of the seal groove 13 on the opposite side of the rotor. Occurs.

  Thereafter, since the piston 9 moves to the rotor side due to the increase in the hydraulic pressure, the gap B is reduced and the restoring force of the seal 15 is further increased. When braking is released, a rollback action occurs due to the elastic restoring force accumulated in the inner periphery of the seal, the piston 9 is returned to the original position, and the seal 15 is also returned to the position shown in FIG. The void portion A is re-formed. This phenomenon is not limited to a seal having a substantially parallelogram cross section, and the same phenomenon occurs even in a rectangular cross section.

Japanese Patent Laid-Open No. 60-4636 (2nd page, FIGS. 1, 5 and 6)

  As described above, in order to give a rollback action to the piston 9 by the seal 15, it is necessary to form the gap A in the seal groove 13 during non-braking and to form the gap B during braking. In addition, a margin for deformation of the seal 15 when the piston 9 is assembled is necessary, and the groove width of the seal groove 13 is formed larger than the width of the seal 15. However, since this gap A exists, excess brake fluid is introduced until the inner periphery of the seal 15 is pressed to the rotor-side wall surface 13d side of the seal groove 13 until the gap A disappears in the initial stage of braking. In spite of the introduction of the brake fluid, it takes time to increase the brake pressure, which is not preferable as a feeling characteristic of the brake.

  Further, when the brake fluid is applied to the piston 9, the seal 15 is bent and deformed, but the amount of bending deformation varies depending on the rigidity of the seal. The rigidity of the seal 15 is affected by the temperature of frictional heat from the piston 9 and the like, and the amount of flexure of the seal 15 changes depending on the temperature, so that the followability of the piston 9 due to wear of the brake pads 3 and 3 and the brake fluid. When the pressure is released, the return performance of the piston 9 is not stable, and there is a possibility that the seal adjustability cannot be kept constant.

  The present invention has been made paying attention to such problems, and it is possible to ensure the rollback action, improve the brake feeling characteristics at the initial stage of braking, and ensure a constant seal adjustability. The object is to provide a braking device with a hydraulically actuable piston.

  In order to solve the above-mentioned problem, a braking device including a hydraulically operated piston according to claim 1 of the present invention is configured such that a piston having a seal on the outer periphery is inserted into a cylinder hole formed in a brake housing, In a braking device including a hydraulically operated piston that operates a piston by hydraulic pressure in a hydraulic chamber formed by one end of the piston and a brake housing and presses a friction member against a rotor to brake, the seal has an outer peripheral portion. A sliding contact with the cylinder hole is accommodated in a seal groove formed on the piston, and a protrusion is provided on the outer side of the side wall of the seal groove opposite to the rotor side surface. ing.

  According to a second aspect of the present invention, there is provided a braking device including a hydraulically actuated piston, wherein the recess on the opposite side wall of the rotor surface of the seal groove that forms the inner portion of the protrusion has a communicating portion that communicates with the brake hydraulic pressure chamber. Yes.

  In the braking device provided with the hydraulically operated piston according to claim 3 of the present invention, the communicating portion is a plurality of cutouts formed on the outer peripheral portion of the seal groove on the side opposite to the rotor side wall.

  According to a fourth aspect of the present invention, in the braking device including the hydraulically operated piston, the communication portion is a plurality of communication holes formed in the vicinity of the outer peripheral portion of the seal groove on the side opposite to the rotor side wall.

  According to the first aspect of the present invention, the seal is provided in the seal groove because the protrusion on the side opposite to the rotor on the side opposite to the rotor of the seal is provided on the outer side on the side opposite to the rotor side of the seal groove. When the hydraulic pressure is introduced into the hydraulic pressure chamber in the initial stage of braking, the piston operates in response to the hydraulic pressure, and the seal is flexed and deformed at the inner portion of the seal against the protrusion. Instead, the outer portion of the portion that contacts the protrusion of the seal is bent and deformed. Therefore, it is not necessary to introduce extra brake fluid for the idle movement of the seal, the feeling of the brake can be improved, and only the outer portion of the seal is deformed and deformed. The change in the flexural rigidity of the seal affected by the temperature is partially limited, and the seal adjustability is stabilized.

  According to the second aspect of the present invention, since the recess on the side wall of the anti-rotor wall inside the seal groove has a communicating portion that communicates with the brake fluid pressure chamber, air bleedability at the time of initial injection of brake fluid. Further, when the seal is stored in the seal groove, the air inside the seal groove is discharged to the brake hydraulic pressure chamber side, so that the seal can be easily attached.

  According to the invention described in claim 3 of the present invention, there are a plurality of outer sides in which the communicating portion connected to the brake hydraulic pressure chamber of the recess on the side wall surface of the non-rotor side wall of the seal groove is formed on the outer periphery of the side wall surface of the anti-rotor side wall of the seal groove. Since the notch is opened, the communication portion can be easily formed.

  According to the invention described in claim 4 of the present invention, since the communicating portion that communicates with the brake hydraulic pressure chamber in the recess on the anti-rotor side wall surface of the seal groove is a communication hole, the rigidity of the anti-rotor side wall surface is increased, When the seal is bent and deformed, the seal side surface can receive a load uniformly at the outer peripheral portion of the anti-rotor side wall surface of the seal groove, and the flexure rigidity of the seal is stabilized.

  Examples of the present invention will be described below.

  A first embodiment of the present invention will be described with reference to FIGS. 1 is a cross-sectional view of a disc brake equipped with a hydraulically operated piston according to a first embodiment of the present invention, FIG. 2 is an enlarged view of a main part of the X portion of FIG. 1, and FIG. FIG. 3B is a partial sectional view of the hydraulically operated piston showing the relationship between the seals, FIG. 3B is a partial sectional view of the hydraulically operated piston showing the relationship between the piston and the seal during braking, and FIG. 3 is a perspective view of the hydraulically operated piston. 4 is a graph showing the relationship between the hydraulic pressure and the hydraulic pressure of the hydraulically operated piston of Example 1 having a seal groove provided with a protrusion and the conventional hydraulically operated piston having no seal groove provided with a protrusion. is there.

  As shown in FIG. 1, three pairs of cylinder holes 25 are formed on both sides of the caliper body 23 with the disc rotor 21 interposed therebetween, and pistons 27 are inserted into the respective cylinder holes 25. The piston 27 is composed of a cylindrical piston having a bottom portion 27 a and a cylindrical portion 27 b, and a brake hydraulic pressure chamber 29 is constituted by the piston bottom portion 27 a and the cylinder hole 25.

  Each brake fluid pressure chamber 29 communicates with a communication passage 31 formed in the caliper body 23 and a communication pipe 33 that communicates with the cylinder holes 25 arranged on both sides, and is configured so that equal fluid pressure is always applied. A brake pipe (not shown) connected to the master cylinder is connected to an introduction port (not shown) leading to the communication passage 31 provided on both sides of the caliper body 23, and the hydraulic pressure from the master cylinder is applied to all brakes. It acts on the hydraulic chamber 29.

  When the hydraulic pressure from the master cylinder is applied to the brake hydraulic pressure chamber 29, the hydraulically operated pistons 27 (hereinafter sometimes simply referred to as “pistons”) inserted in the cylinder holes 25 slide to friction pads 37. , 39 are pressed against the disc rotor 21 to apply a braking action to the disc rotor 21, and when the hydraulic pressure from the master cylinder is no longer applied, the piston 27 is retracted by the rollback force of the seal 41, and the braking is applied. The action is released.

  A seal groove 43 (see FIG. 2) for storing the seal 41 is provided in the vicinity of the bottom 27a of the piston 27, and a plurality of through holes 27c are randomly formed in the cylindrical portion 27b. Since the seal 41 is in the vicinity of the bottom portion 27a of the piston 27 and is located away from the friction pads 37 and 39, the seal 41 is hardly affected by the frictional heat and the durability thereof is improved.

  The plurality of through holes 27 c restrict the frictional heat generated by the braking action from being transmitted to the brake hydraulic pressure chamber 29 via the friction pads 37 and 39. That is, since the through hole 27c is formed in the cylindrical portion 27b of the piston 27 as a region where the cross-sectional area decreases, the cross-sectional area of the piston where heat is transmitted to the brake fluid side is reduced, and the increase in the brake fluid temperature is mitigated.

  As shown in FIG. 2A, the outer peripheral portion 41 a of the seal 41 is in sliding contact with the cylinder hole 25, and the inner peripheral portion 41 b is accommodated in a seal groove 43 formed in the piston 27. A protrusion 27A is provided on the outer side of 43a so as to contact the outer side of the side 41A of the seal 41 on the side opposite to the rotor. The rotor-side side surface 41B of the seal 41 is in contact with the rotor side wall surface 43b of the seal groove 43 substantially on the entire surface except for the outer peripheral portion.

  Since the protrusion 27A is provided on the outer side of the rotor groove side surface 43a of the seal groove 43, when the seal 41 is stored in the seal groove 43, a gap 43c is formed in the inner portion of the protrusion. And as shown in FIG. 3, the notch 27B which the some outer side opened to the outer periphery of the bottom part 27a of the piston 27 which comprises the anti-rotor side wall surface 43a of the seal groove 43 is provided in the circumferential direction, and the space | gap part 43c is provided. The brake fluid pressure chamber 29 communicates with these notches 27B. Since the gap 43 c communicates with the brake fluid pressure chamber 29 in this manner, the air gap 43 c can be easily released when the brake fluid is initially injected, and when the seal 41 is stored in the seal groove 43, the seal groove 43. The inner air is discharged to the brake hydraulic pressure chamber 29 side without being compressed, and the seal 41 can be easily attached. Further, since the cutout 27B only needs to be cut from the outside toward the inside, the cutout 27B can be easily formed.

  FIG. 2A shows the relationship between the piston and the seal before the braking action, and when the hydraulic pressure is not introduced into the hydraulic pressure chamber 29, the side surface 41A on the side opposite to the rotor of the seal 41 is the tip of the protrusion 27A. The rotor side surface 41B of the seal 41 is in contact with the rotor side wall surface 43b of the seal groove 43.

  When the hydraulic pressure is introduced into the hydraulic pressure chamber 29, the piston 27 immediately slides toward the rotor side without the idle movement of the inner portion of the seal 41, as shown in FIG. While being pressed by the protrusion 27A, the outer portion of the protrusion 27A is bent and deformed. This bending deformation of the seal 41 acts as a rollback when the brake is released, returning the piston 27 to the initial brake position. When the friction pads 37 and 39 are worn and the brake gap is equal to or larger than a predetermined value, the seal 41 is bent and deformed, and the outer peripheral portion 41a moves to the rotor side together with the piston 27 while sliding on the cylinder hole 25. When the brake is released, the piston 27 is returned by the rollback action of the seal 41 by an amount that makes the brake clearance a specified value. As described above, since only the outer portion of the seal is deformed by deformation, the change in the bending rigidity of the seal affected by the temperature of the frictional heat is partially limited, and the seal adjustability is stabilized.

  FIG. 4 shows a test of the relationship between the fluid volume and the fluid pressure when the brake fluid pressure is applied to the conventional hydraulically operated piston having no protrusion in the seal groove and the piston 27 of the first embodiment having the protrusion. The results are shown in a graph. As can be seen from the figure, in the initial stage of braking, the conventional piston requires an extra amount of fluid to receive the same fluid pressure as the piston of the first embodiment. As described above, it can be seen that the conventional one is inferior in the braking feeling of the brake because the braking force is hardly transmitted even though the amount of liquid is supplied in the early stage of braking.

  FIG. 5A is a perspective view of a hydraulically operated piston according to the second embodiment, and FIG. 5B is a partial cross-sectional view of the hydraulically operated piston according to the second embodiment. Also in the second embodiment, the outer peripheral portion of the seal 51 is in sliding contact with the cylinder hole 25, and the inner peripheral portion of the seal 51 is accommodated in the seal groove 53 formed in the piston 57. Protrusions 57 </ b> A that come into contact with the outer side portions 51 </ b> A on the side opposite to the rotor of the seal 51 are provided.

  When the seal 51 is housed in the seal groove 53, a gap 53c is formed in the inner portion of the protrusion 57A. A communication hole 57B that communicates with the gap 53c is formed in the bottom 57a of the piston 57 that constitutes the side wall surface of the seal groove 53 opposite to the rotor. The second embodiment is different from the first embodiment in that the outer peripheral portions of the notch 27B are connected by a bridge 58 to provide a communication hole 57B. As a result, air can easily escape from the gap 53c when the brake fluid is initially injected, and when the seal 51 is housed in the seal groove 53, the air inside the seal groove 53 is not compressed and the brake fluid pressure chamber 29 side is compressed. The seal 51 can be easily attached. In addition, unlike the notch of the invention of the first embodiment, the outer peripheral portion of the bottom 57a of the piston 57 is not notched, so that the rigidity of the anti-rotor side wall surface 53a is increased, and when the seal 51 is bent and deformed, However, the load can be uniformly received at the outer peripheral portion of the side wall surface of the rotor opposite to the seal groove 53, and the flexural rigidity of the seal can be stabilized.

  As described above, the embodiments of the present invention have been described with reference to the drawings. However, the specific configuration is not limited to these embodiments. For example, in this embodiment, the disc brake is described as the braking device. Even if there is a change or addition within a range not departing from the gist of the present invention, it is included in the present invention.

  In addition, if the position where the protrusion abuts on the side of the seal is too low, the change in flexural rigidity will increase due to the effect of frictional heat temperature, and the piston assembly will be hindered. About 1/2 or more is preferable.

It is sectional drawing of the disc brake provided with the hydraulic-action piston of Example 1 of this invention. It is a principal part enlarged view of the X section of Drawing 1, and (a) is a fragmentary sectional view of a hydraulically-actuated piston showing the relation between a piston and a seal before braking action, and (b) is a piston and seal of braking action. It is a fragmentary sectional view of the hydraulically-actuated piston showing the relationship. It is a perspective view of a hydraulically operated piston. It is a graph which shows the relationship between the liquid quantity and the hydraulic pressure with respect to the hydraulic operation piston of Example 1 which has the seal groove provided with the protrusion, and the conventional hydraulic operation piston which is not provided with the protrusion in the seal groove. (A) is a perspective view of the hydraulically operated piston according to the second embodiment, and (b) is a partial sectional view of the hydraulically operated piston according to the second embodiment. (A) is a sectional view of a disc brake having a conventional hydraulically operated piston, and (b) and (c) are operation explanatory views before and after the braking action of the seal.

Explanation of symbols

21 ... Rotor 23 ... Caliper body (brake housing)
25 ... Cylinder hole 27 ... Piston (hydraulic operating piston)
27a ... Bottom 27b ... Cylindrical part 27c ... Through hole 27A ... Projection 27B ... Notch 29 ... Brake hydraulic pressure chamber 31 ... Communication path 33 ... Communication pipe 37, 39 ... Friction pad 41 ... Seal 41a ... Outer peripheral part 41b ... Inner peripheral part 41A ... Side surface on the opposite rotor side 41B ... Side surface on the rotor side 43 ... Seal groove 43a ... Anti-rotor side wall surface 43b ... Rotor side wall surface 43c ... Gap 51 ... Seal 51A ... Anti-rotor side surface 53 ... Seal groove 53a ... Anti-rotor side wall surface 53c ... Cavity 57 ... Piston 57a ... Bottom 57A ... Protrusion 57B ... Communication hole

Claims (4)

  A piston having a seal on the outer periphery is inserted into a cylinder hole formed in the brake housing, and the piston is operated by the hydraulic pressure in the hydraulic chamber formed by one end of the piston and the brake housing, so that the friction member becomes a rotor. In the braking device including a hydraulically operated piston that presses and brakes, the seal has an outer peripheral portion that is in sliding contact with the cylinder hole, and an inner peripheral portion that is housed in a seal groove formed in the piston, and the side wall surface of the rotor opposite to the seal groove A braking device comprising a hydraulically actuated piston having a protrusion that abuts on the outer side portion of the seal on the side opposite to the rotor.   The braking device provided with a hydraulically-actuated piston according to claim 1, wherein the concave portion on the side wall of the rotor opposite to the seal groove constituting the inner portion of the protrusion has a communicating portion connected to the brake hydraulic pressure chamber.   The braking device provided with a hydraulically-actuated piston according to claim 2, wherein the communication portion is a plurality of notches formed on the outer peripheral portion of the seal groove on the side wall opposite to the rotor.   The braking device provided with a hydraulically operated piston according to claim 2, wherein the communication portion is a plurality of communication holes formed in the vicinity of the outer peripheral portion of the seal groove on the side opposite to the rotor side wall.

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