JP2007010056A - Disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disc brake for preventing an increase in dragging torque during non-braking and the acceleration of wear of a pad and a rotor due to dragging while minimizing the occurrence of dragging during non-breaking resulting from a sliding failure of a sliding part which induces the dragging. <P>SOLUTION: The sliding pin type disc brake comprises caliper guide mechanisms 5 each having a guide hole 3 and a sliding pin 4 in the axial direction of the rotor corresponding to a support 1 and a caliper 2, the sliding pin 4 being inserted into the guide hole 3, the caliper guide mechanisms 5 being installed on the turn-in and turn-out sides of the rotor for slidably supporting the caliper 2 in the axial direction of the rotor. On at least one metal surface portion of the sliding part, high speed shot-peening treatment is applied with finely-crushed solid lubricating material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for improving brake characteristics of a disc brake, and is capable of effectively and significantly reducing drag due to a brake pad return failure or the like with an extremely simple measure.

  The basic mechanism of the disc brake is as shown in FIG. 9. In the case of a slide pin type, the support 1 and caliper 2 are provided with guide holes (or pin holes) 3 and slide pins (or guide pins) in the rotor axial direction. ) 4 are provided correspondingly, and caliper guide mechanisms 5 formed by inserting the slide pins 4 into the guide holes 3 are installed on the return side and the return side of the rotor to support the caliper 2 so as to be slidable in the axial direction of the rotor. It is configured. This brake presses the left pad 6 shown in the figure with a piston inserted into the cylinder hole of the caliper to make sliding contact with the rotor, and the right pad 6 shown in FIG. It is pressed and brought into sliding contact with the rotor.

  By the way, in this type of brake, it is inevitable that the pitch between the guide holes and the pitch between the slide pins becomes non-uniform, and in order to absorb this deviation, the gap between the guide hole 3 and the slide pin 4 inserted into the hole is inevitable. In order to prevent rattling noise (impact noise between the pin and the guide hole) due to this clearance, a rubber cushioning material is interposed between the slide pin and the guide hole.

  The rubber bush 7 and the rubber ring 8 are the cushioning materials. In this example, the rubber bush 7 and the rubber ring 8 serving as cushioning materials are integrally formed with the rubber boot 9, but a separate member from the rubber boot is fitted into the outer periphery of the slide pin 4 or the inner surface of the guide hole 3. There are also things.

  In some cases, a low friction coefficient sleeve is interposed between the rubber bush 7 and the slide pin 4 in order to reduce sliding resistance.

  As described above, when a rubber cushioning material is interposed between the guide hole and the slide pin, the metal (slide pin and guide hole both) and the rubber are pressed against sliding, so the guide hole and the slide pin are in direct pressure contact. Compared with the case of sliding, the sliding resistance increases, and problems such as an increase in drag torque during non-braking and wear of the pad and rotor due to drag are caused.

  The sleeve with the low coefficient of friction as described above is used to solve the problem. It improves the sliding of the slide pin and makes the caliper return smoothly when the pressure is released. If the sleeve is integrated with the rubber bush 7 for the purpose of being easily damaged locally by the slide pin, etc., or improving the handling and reducing the number of assembly steps, the softness of the rubber bush 7 can be reduced. The inertia is lowered and the assembling property is impaired. From such a problem recognition, a technique that solves the problem of reducing the sliding resistance of the above-described slide pin without deteriorating the durability and assemblability of components is disclosed in Japanese Patent Application Laid-Open No. 9-32871. Are listed. The configuration of this is as follows.

  As for the caliper guide mechanism 5 of the prior art described above, the upper one in FIG. 10 has a rubber bush 7 integral with the rubber boot 9 interposed between the guide hole 3 and the slide pin 4. The lower one is such that a rubber ring 8 integral with the rubber boot 9 is interposed between the guide hole 3 and the slide pin 4.

  Further, a sliding resistance reducing material 12 formed in a net shape is interposed between the rubber bush 7 and the slide pin 4 and between the rubber ring 8 and the slide pin 4.

  The net-like sliding resistance reducing material 12 is formed of organic fibers, but can also be formed of inorganic fibers such as carbon fibers, glass fibers, and steel fibers. In addition, if the material is softer than the slide pin, it is not necessary to use a knitted mesh. As shown in FIG. 11, the sliding resistance reducing material is formed in a net shape by opening a large number of holes (the shape is arbitrary) in the sheet or cylinder. 12a may be used.

  Further, when used integrally with the sliding surface of the rubber bush 7 or the rubber ring 8, it is not necessary to have a net-like shape, and it may be a spiral arrangement, a parallel arrangement, or a random arrangement. The shape may be integrated with the sliding surface portion such as the rubber bush 7 and distributed on the average, and this may be slidably contacted with the slide pin.

  Since the sliding resistance reducing material 12 follows the elastic deformation of the rubber cushioning material such as the rubber bush 7, an excessive force is not applied to the portion, and the flexibility of the cushioning material is maintained. Therefore, the sliding resistance of the slide pin can be reduced and drag during non-braking can be reduced without deteriorating the durability and assemblability, and the reliability and performance of the slide pin type disc brake can be further improved. Figured.

  The conventional technique shown in FIG. 10 as described above is a conventional technique close to the present invention, and this conventional technique aims to reduce the operation failure of the guide mechanism by the slide pin, the sliding resistance due to the unstable operation, and the drag. However, since this is the one in which the sliding resistance reducing material 12 is added to the rubber cushioning material such as the rubber bush 7, the structure of the rubber cushioning material is complicated, and the rubber cushioning material is in an overheated state. Therefore, there is a problem in the durability of the sliding resistance reducing material 12.

  Further, in the disc brake, when a malfunction of the self-adjusting mechanism (automatic adjustment mechanism of the clearance of the brake surface) due to a sliding failure between the brake piston and the seal (seal ring) occurs (piston return failure state) Clearance is not possible during non-braking, which causes drag.

Further, in the disc brake, if the relative movement during braking of the brake pad and the caliper body is not smooth, the caliper does not return smoothly during non-braking and dragging occurs.
JP-A-9-32871

The present invention aims to prevent an increase in drag torque during non-braking and to prevent pad and rotor wear from being accelerated due to drag, which is caused by non-sliding failure of the sliding portion that induces drag. The main problem is to reduce as much as possible the occurrence of drag during braking. And the concrete subject for that is as follows.
(A) To reduce the sliding resistance of the guide mechanism due to the slide pin, so that drag during non-braking due to malfunction and instability of the guide mechanism can be reduced for a long period of time;
(B) Stabilizing the sliding contact resistance between the brake piston and the seal, reducing the variation in the fluid amount due to the experience fluid pressure, and reducing the drag during non-braking,
(C) To reduce the drag at the time of non-braking by stabilizing the sliding contact between the rotor and the brake pad so that the relative movement between the brake pad and the caliper body is smoothly performed during braking.
In addition, the above-mentioned “change in fluid volume due to experience fluid pressure” is, in short, that a fluid volume difference occurs due to a slip difference between the seal when the experience pressure is low and when the experience pressure is high, and the variation is between the brake piston and the seal. This is caused by variations in sliding resistance.

[Solution 1]
A means 1 for solving the above main problem is that a caliper guide mechanism 5 is provided in which a support hole 1 and a caliper 2 are provided with a guide hole 3 and a slide pin 4 corresponding to the rotor axial direction, and the slide pin 4 is inserted into the guide hole 3. Of the slide pin type disc brake having a structure in which the caliper 2 is slidably supported in the axial direction of the rotor. This is that the portion was subjected to high-speed shot peening treatment with fine powder of solid lubricant.

[Solution 2]
Means 2 for solving the above problems includes a rotor that rotates together with a wheel, a pair of pads disposed to face the side surfaces of the rotor, and a part of the vehicle body that is disposed across the pair of pads and the rotor. In a fixed disc brake with a caliper that is fixed to
That is, the metal surface portion of at least one sliding portion has been subjected to high-speed shot peening treatment with fine powder of solid lubricant.

[Embodiment 1]
In Embodiment 1, the solid lubricant in Solution 1 and Solution 2 is molybdenum disulfide or graphite.

[Solution 3]
Means 3 for solving the specific problem (a) is that the metal surface of the sliding portion in the solution means 1 is the outer peripheral surface of the guide pin (slide pin) that is in sliding contact with the pin hole (guide hole). It is.

[Solution 4]
The means 4 for solving the specific problem (b) is such that the metal surface of the sliding portion in the solving means 1 is the outer peripheral portion of the piston that is in sliding contact with the cylinder hole.

[Solution 5]
The means 5 for solving the specific problem (c) is such that the metal surface of the sliding portion in the solution means 1 is the open end of the piston that is in pressure contact with the pressure plate back side.

[Solution 6]
The means 6 for solving the specific problem (c) is such that the metal surface of the sliding portion in the solution means 1 is the metal surface of the pressing flat portion of the caliper that is in pressure contact with the pressure plate back side.

[Solution 7]
The means 7 for solving the specific problem (c) is such that the metal surface of the sliding portion in the solution means 1 is the surface of a metal shim that is in pressure contact with the pressure plate back side.

[Solution 8]
Means 8 for solving the above specific problem (c) is that the metal surface of the sliding portion in the solution means 1 is interposed between the pressure plate back side and is in pressure contact with each other. This is the mutual pressure contact surface of one shim.

1. Effects of Inventions of Claims 1 and 2 (Solution 1 and Solution 2)
According to the first and second aspects of the invention, the solid lubricant is embedded in the metal surface portion, the resistance of the sliding portion is reduced, and the grease is stable for a long period of time and the grease can be eliminated. Therefore, the behavior of the brake is smooth and stable for a long time. In addition, when grease is applied, the metal surface portion having minute irregularities becomes an oil reservoir, and the effect is further enhanced.

2. Effect of Invention of Claim 4 (Solution means 3)
Sliding resistance is reduced by applying high-speed shot peening to the sliding surface of the slide pin with fine powder such as glass or alumina beads. In addition, micro dimples are generated on the sliding surface of the slide pin, and when grease is applied, this minute unevenness acts as an oil reservoir, and as a result, a grease film layer is always formed between the slide pin, the boot, and the bush. The friction is reduced through the lubricant, and the sliding resistance is small.
When the shot material is a solid lubricant such as molybdenum disulfide or graphite and subjected to high-speed shot peening, the fine shot material is embedded in the slide pin sliding surface layer with a high distribution density.
Therefore, according to the invention of claim 4, the sliding resistance of the guide pin is reduced, the guide pin's twisting and the seal portion resistance are reduced and stable, and as a result, uneven wear and idling rotor aggression are prevented. Alleviated.

3. Effect of Invention of Claim 5 (Solution 4)
Grease is interposed between the piston and the seal, but since the piston surface is smooth, grease and brake fluid are easily wiped off by repeated braking action, and a boundary friction state is created between the seal and the piston. In some cases, sticking may occur over time, and in this state, the static resistance during initial movement increases, which adversely affects the pedal feeling during brake operation. However, according to the invention of claim 5, sliding resistance is reduced by high-speed shot peening, and minute irregularities serve as an oil reservoir by generating minute irregularities on the surface of the piston. A brake fluid or a grease film layer is always formed between the seal and the piston, sticking of the seal is suppressed, and the variation in the static resistance of the contact is reduced and the difference from the dynamic resistance is also reduced.
Accordingly, sticking of the seal to the piston is reduced, the sliding resistance is stabilized, and the self-adjusting performance is stabilized.

4). Effects of the Invention of Claim 6 (Solution 5)
According to the sixth aspect of the present invention, the opening end surface of the piston, that is, the opening end surface of the piston on the pressure plate side is a surface obtained by subjecting molybdenum disulfide or graphite powder to high-speed shot peening treatment. The contact surface between the surface subjected to the high-speed shot peening treatment and the pressure plate back surface has a smaller friction coefficient than that of the surface not subjected to the high-speed shot peening treatment, which is much larger than the friction coefficient between the rotor and the brake pad. Small. Therefore, since the brake pad at the time of braking slips with respect to the caliper body, the caliper is not twisted and the required contact state between the brake pad and the rotor is stably maintained.

5. Effect of the Invention of Claim 7 (Solution means 6)
According to the invention of claim 7, since the pad side is easily slipped with respect to the pressing flat portion of the caliper, and its sliding characteristics are stabilized, the caliper is not twisted as in the case of the invention of claim 6, The brake pad is kept in stable contact with the rotor.

6). Effects of the invention of claim 8 (Solution means 7)
According to the eighth aspect of the present invention, the friction coefficient of the contact surface between the shim and the pressure plate is reduced, and the shim can easily slide with respect to the brake pad. There is no damage, and uneven wear of the brake pads and idling rotor attack are alleviated.

7). Effect of the Invention of Claim 9 (Solution 8)
According to the ninth aspect of the present invention, the shims can slip easily, and the caliper is not twisted as in the case of the sixth aspect of the invention, and the uneven wear of the brake pads and the idling rotor attack are alleviated.

Next, examples will be described with reference to the drawings.
In the present invention, a so-called WPC (Wide Peering Cleaning) or Winder Process Craft (WPC) processing technique is used for a disc brake device. This WPC processing technique is a known technique and is as follows.
That is, for example, a particle diameter 200μm or less (e.g., 70 [mu] m) is projected to the metal surface with compressed air to fine powder in 100 m / s or faster (shot peening), A ₃ transformation point and the outermost surface of a ferrous metal As described above, with non-ferrous metals, the surface property is improved by increasing the temperature above the recrystallization temperature, instantaneously melting and recrystallizing the metal surface to be treated, and forming minute irregularities on the metal surface (improving hardness, coating) Is a surface modification treatment technology that improves the slidability and mechanical properties of the metal surface, etc., and solid lubrication such as molybdenum disulfide and graphite as the above fine powder By using a material, it can be bitten and fixed on the metal surface to improve the sliding characteristics and improve the durability of the surface.

[Example 1]
Embodiment 1 shown in FIGS. 1 and 2 is an embodiment of the solving means 3 and the WPC treatment technology is applied to the surface of the shaded portion of the slide pin or guide pin (main pin 21, sub pin 22) made of non-heat treated metal material. Is applied. And the guide mechanism by the main pin 21 and the sub pin 22 does not differ from the said prior art.
The clearance between the main pin 21 and the pin hole 24 is about 150 μm, and the clearance between the sub pin 22 and the pin hole is about 300 μm.
The main pin 21 is fitted with a bush 23a (one integrated with the pin boot 23) with a tightening margin, and the sub pin 22 is fitted with a bush 23a integral with the pin boot 23 and a pin bush 25 with a small margin.
The WPC treatment for the guide pins (main pin 21, sub pin 22) is a projection of molybdenum disulfide powder (purity 98.5%) with a particle size of 50 μm with compressed air at a speed of 100 m / s. As a result, molybdenum disulfide particles, which are solid lubricants, are imparted to the metal surface, and a lubricating effect is obtained. Concavities and convexities having a depth of 40 μm or less are formed, and in the case of applying grease, a grease pool is formed and the lubricating effect is enhanced.

[Example 2]
A second embodiment shown in FIG. 3 is an embodiment of the solution means 4 in which the outer peripheral surface of the carbon steel piston 31 is subjected to WPC treatment.
The WPC treatment for the piston 31 fitted in the cylinder S is a projection of molybdenum disulfide having a particle diameter of 50 μm (purity 98.5%) with compressed air at a speed of 100 m / s. As a result, the inner peripheral surface of the seal 32 is brought into intimate contact with the piston surface, but there is a minute gap s between the inner peripheral surface of the seal 32 and the piston surface, the lubricant is held in this gap, and disulfide is also present. Molybdenum fine particles are fixed, irregularities with a depth of 40 μm or less are formed, and grease is collected to increase the lubrication effect. It is reliably avoided that the inner peripheral surface of the seal 32 sticks to the piston surface, and the frictional force is stable. To do. That is, the difference between static friction and dynamic friction does not increase due to lack of lubrication or the like, and the difference between static friction and dynamic friction is always stable.
Accordingly, the self-adjusting action is stabilized and no malfunction (piston return defect) occurs.

Example 3
A third embodiment shown in FIGS. 4 and 5 is an embodiment of the solving means 5 and 7, and shims 41 and 41 (made of stainless steel) having a thickness of 0.4 mm between the brake pads 40 and 40 and the piston and caliper. In the disc brake having the intervening structure, the surface of the shim 41, 41 that contacts the pressure plate 42 of the brake pad 40 is subjected to WPC treatment.
The WPC treatment on the surface of the shim 41, 41 that contacts the pressure plate 42 of the brake pad 40 is a projection of molybdenum disulfide having a particle size of 50 μm (purity 98.5%) with compressed air at a speed of 100 m / s. . As a result, irregularities with a depth of 40 μm or less are formed. The pressure plate 42 of the brake pad 40 contacts the surface of the shim 41, but the molybdenum disulfide fine particles are fixed to the shim, so that the friction coefficient μ ₂ between the pressure plate 42 of the brake pad 40 and the shim 41 is 0.22. On the other hand, the friction coefficient μ ₁ between the rotor and the brake pad is 0.3 to 0.4, and the frictional resistance F2 between the pressure plate 42 and the shim 41 of the brake pads 40, 40 is braked. This relationship is stable because the braking resistance F1 applied to the pad 40 is significantly smaller (F2 <F1).

Therefore, the pressure contact surface between the pressure plate 42 and the shim 41 becomes a braking sliding surface, and the braking resistance F1 is slid to escape here. Therefore, the braking resistance F1 is not transmitted to the caliper as it is and is not greatly squeezed.
The shim 41 shown in FIG. 4 contacts the pressure plate 42 as a whole, but may be a circular shim 41A that partially contacts the pressure plate 42, as shown in FIG. In this case, the front surface 41f of the circular shim 41A may be subjected to WPC processing, and four elastic claws 41B may be provided on the rear surface, and the end of the brake piston 31 may be fitted and connected thereto.

Example 4
Example 4 shown in FIG. 6 is a disc brake in which shim 41, 41 and shim 45, 45 of stainless steel and 0.4 mm in thickness are interposed between brake pads 40, 40 and pistons and calipers. The surface of the shims 41, 41 that are in contact with the shims 45, 45 is subjected to WPC treatment.
The WPC treatment on the surfaces of the shims 41 and 41 that are in contact with the shims 45 and 45 is a projection of molybdenum disulfide having a particle size of 50 μm (purity 98.5%) with compressed air at a speed of 100 m / s. As a result, irregularities of 40 μm or less are formed. As a result, the shim 45 is brought into contact with the surface (rough surface) of the uneven shim 41, but there is a minute gap between the press contact surfaces, and the molybdenum disulfide fine particles are fixed. The friction coefficient μ ₃ between 45 decreases from 0.22 to 0.13, while the friction coefficient μ ₁ between the rotor and the brake pad is 0.3 to 0.4, and the friction between the shim 41 and the shim 45 The resistance F3 is significantly smaller than the braking resistance F1 applied to the brake pad 40 (F3 <F1), and this relationship is stable. Therefore, it is avoided that the braking resistor F1 is transmitted to the caliper as it is and the caliper is greatly distorted.

In the fourth embodiment, since the shim 41 is provided with a plurality of holes 41a, the friction coefficient between the shim 41 and the shim 45 can be further reduced by applying grease to the shim surface.
Further, a rubber coating layer may be provided on the contact surface of the shim 41 with the pressure plate 42 to prevent the brake from squeaking due to contact improvement.

Example 5
The fifth embodiment shown in FIG. 7 is an embodiment of the solving means 5 and 6, and does not perform the WPC process on the shim, but opens the end surface 31e that abuts the pressure plate 42 of the piston 31 (or the caliper inner surface 31e of the caliper). ') To which WPC processing has been applied.
The WPC treatment on the end surface of the piston 31 (or the inner surface of the claw portion) is a projection of molybdenum disulfide powder (purity 98.5%) with a particle size of 50 μm with compressed air at a speed of 100 m / s. As a result, irregularities with a depth of 40 μm or less are formed. Thereby, the pressure plate 42 is brought into contact with the piston end surface (or the inner surface of the claw portion), but there is a minute gap between the pressure contact surfaces, and the molybdenum disulfide fine particles are fixed, so that the piston open end surface 31e. (Or the caliper claw inner surface 31e ′) and the pressure coefficient μ ₄ between the pressure plate 42 are reduced from 0.22 to 0.13, while the coefficient of friction μ ₁ between the rotor and the brake pad is 0.3 to 0. .4, and the frictional resistance F4 between the piston open end surface 31e (or the caliper claw inner surface 31e ') and the pressure plate 42 is significantly smaller than the braking resistance F1 applied to the brake pad 40 (F4 <F1). Is stable. Therefore, it is avoided that the braking resistor F1 is transmitted to the caliper as it is and the caliper is greatly distorted.

Example 6
Example 6 shown in FIG. 8 is an example of solving means 4, 5, 7, and 8 in the OPPOSED type disc brake. Although not shown in detail in FIG. 8, there are similar effects.

These are sectional drawings which show the one part principal part of Example 1. FIG. These are sectional drawings which show the other principal part of Example 1. FIG. (A) is sectional drawing which shows a part principal part of Example 2, (b) is a partially expanded view. These are the principal part perspective views of Example 3. FIG. These are the principal part perspective views of the other form of Example 3. FIG. These are the principal part perspective views of Example 4. FIG. These are the principal part perspective views of Example 5, (a) is a contact surface with the pressure plate of a piston, and its related figure, (b) is a figure of the contact surface with the pressure plate of a caliper and its nail | claw part. is there. These are sectional drawings of the opposed type disc brake of Example 6. FIG. FIG. 3 is a partially broken plan view showing a basic structure of a slide pin type disc brake. These are principal part sectional drawings of a prior art. FIG. 11 is a perspective view of an example of a sliding resistance reducing material in the prior art of FIG. 10.

Explanation of sign

1 ... support 2 ... caliper 3 ... guide hole (pin hole)
4 ... Slide pin (guide pin)
5 ... caliper guide mechanism 6 ... pad 7 ... rubber bush 8 ... rubber ring 9 ... rubber boot 12, 12a ... sliding resistance reducing material 21 ... main pin 22 ... Sub pin 23 ... Pin boot 23a ... Bush 24 ... Pin hole 25 ... Pin bush 31 ... Piston 31e ... Open end face 32 ... Seal 40 ... Brake pad 41 ... Shim 41a ... hole 41A ... circular shim 41B ... elastic claw 41f ... front surface of circular shim 41A 42 ... pressure plate 45 ... shim S ... cylinder s ... minute distance

Claims (9)

A rotor that rotates together with the wheels, a pair of pads arranged opposite to the side of the rotor, a caliper arranged across the pair of pads and the rotor, a support fixed to a part of the vehicle body, and the support The caliper is provided with a guide hole and a slide pin in the rotor axial direction corresponding to the caliper, and a caliper guide mechanism in which the slide pin is inserted into the guide hole is installed on the inlet side and the outlet side of the rotor to place the caliper in the rotor axial direction. In the slide pin type disc brake with a structure that supports the slidable to the
A disc brake in which a metal surface portion of at least one sliding portion is subjected to high-speed shot peening treatment with fine powder of a solid lubricant. A fixed disc brake having a rotor that rotates together with the wheels, a pair of pads disposed opposite to the side surfaces of the rotor, and a caliper that is disposed across the pair of pads and the rotor and is fixed to a part of the vehicle body. In
A disc brake in which a metal surface portion of at least one sliding portion is subjected to high-speed shot peening treatment with fine powder of a solid lubricant.   A disc brake in which the solid lubricant according to claim 1 or 2 is molybdenum disulfide or graphite.   4. The disc brake according to claim 1, wherein the metal surface of the sliding portion is the outer peripheral surface of the guide pin that is in sliding contact with the pin hole.   4. A disc brake in which the metal surface of the sliding portion according to claim 1 is an outer peripheral portion of a piston in sliding contact with a cylinder hole.   4. A disc brake in which the metal surface of the sliding portion according to claim 1 is an open end portion of a piston that is in pressure contact with the pressure plate back side.   4. The disc brake according to claim 1, wherein the metal surface of the sliding portion is the metal surface of the pressing flat portion of the caliper that is in pressure contact with the pressure plate back side.   4. The disc brake according to claim 1, wherein the metal surface of the sliding portion is a surface of a metal shim that is in pressure contact with the pressure plate back side.   4. The disc brake according to claim 1, wherein the metal surface of the sliding portion is a mutual pressure contact surface of one of a plurality of metal shims that are interposed on the back side of the pressure plate and are in pressure contact with each other.

Images