JPH10318307A - Disk brake pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely suppress occurrence of brake noise by carrying out surface hardening on at least one side part in both side parts in a rotational direction of a disk rotor of a pad main body in a disk brake pad. SOLUTION: In a disk brake device, a pair of disk brake pads 1 are arranged in a brake caliper, and consist of a pad main body 2 and a back plate 4. The pad main body 2 is brought into contact with a disk rotor so as to generate frictional force, and is formed in a raw material formed by mixing an abrasive, a lubricating material, and a binder with each other. In the disk brake pad 1, surface hardening is carried out on both side parts of the pad main body 2. The surface hardening is carried out by pushing a part corresponding to a surface hardening part 6 to a heat plate to be heated. When surface hardening is carried out, a frictional coefficient of the surface hardening part 6 is reduced comparing with the frictional coefficient of the other part, and thereby, generation of brake noise is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc brake pad, and more particularly to a disc brake pad that generates a braking force by frictionally contacting a disc rotor.

[0002]

2. Description of the Related Art A disk brake device for a vehicle is provided with a disk rotor rotating together with a wheel in a predetermined length along a front and rear direction of rotation of the disk rotor (a forward direction is called a leading side and a rear direction is called a trailing side). The friction pad makes a frictional contact with the brake pad.
Generally, a brake pad is made of an abrasive (Al ₂ O _3, S
iO _2, etc.) and a lubricant _{(MoS 2, Sb 2 S 3} , C , etc.) and the binding material by (phenolic resin) has a configuration obtained by mixing at a predetermined ratio.

In the above-described disc brake device, a loud noise called "brake squeal" sometimes occurs due to friction between the disc rotor and the brake pad during braking. This brake squeal is related to the hardness of the pad body (lining portion) of the disc brake pad. That is, when the hardness of both sides of the pad body is high with respect to the rotation direction of the disk rotor, when the disk brake pad is pressed against the disk rotor, the surface pressure at both sides becomes higher than the surface pressure at the center. .
Therefore, it is considered that the surface pressure distribution is not uniform at the contact surface between the disk brake pad and the disk rotor, and the brake squeal is caused by this.

Therefore, conventionally, in order to suppress the occurrence of the brake squeal, there has been proposed a disc brake pad in which the hardness of both sides of the pad body is lower than the hardness of the center portion (Japanese Patent Laid-Open No. 2-134426). No.).

[0005]

By making the hardness of both sides of the pad body lower than the hardness of the central portion as described above, the surface pressure distribution on the contact surface between the disc brake pad and the disc rotor is uniform. As a result, the vibration characteristics are improved (that is, the vibration is reduced), and the occurrence of brake squeal can be suppressed.

[0006] However, in addition to the above-mentioned vibration characteristics, the squealing force of the brake squeal has a strong influence. here,
The oscillating force is a friction force generated on the contact surface between the disk brake pad and the disk rotor, and the oscillating point is a position where the friction force is generated. Therefore, in the conventional disk brake pad, although the vibration itself can be reduced by improving the vibration characteristics, the vibration generating force and the vibration generating point are not improved, and the occurrence of brake squeal is suppressed. Was inadequate.

The present invention has been made in view of the above points, and a disk brake pad capable of reliably suppressing the occurrence of brake squeal by performing surface burning on both sides or one side of the pad body. The purpose is to provide.

[0008]

According to the present invention, there is provided a disk brake pad for generating a braking force by bringing a pad body into frictional contact with a disk rotor. The surface is baked on at least one side of both sides in the direction.

As described above, by performing surface baking on the pad body, the pad body undergoes changes in physical characteristics such as a decrease in friction coefficient and a decrease in hardness. In addition, since the above-described surface baking is selectively performed on at least one side portion (hereinafter, simply referred to as a side portion) of both side portions of the pad body,
The above-mentioned changes in the physical characteristics also occur selectively on the side of the pad body.

As described above, the change in each physical characteristic selectively occurring in the pad body has the following effect on brake squeal. That is, the vibration coefficient at the time of occurrence of brake squeal can be reduced by reducing the friction coefficient of the pad body side portion. In addition, since the hardness of the pad body side portion is reduced, vibration characteristics can be improved as in the related art.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a disc brake pad 1 according to one embodiment of the present invention, and FIGS. 3 and 4 show a disc brake device 10 to which the disc brake pad 1 is mounted. FIG. 3 is a front view of the disc brake device 10, and FIG. 4 is a side sectional view of the disc brake device 10.

In this embodiment, the disc brake device 10
As an example, a case using a caliper floating type will be described. However, the application of the disc brake pad 1 according to the present invention is not limited to the caliper floating type, but can also be applied to other types of disc brake devices.

The disc brake device 10 has a structure in which a pair of disc brake pads 1 (an outer brake pad 1a and an inner brake pad 1b) are disposed inside a brake caliper 12 with a disc rotor 14 interposed therebetween. . The brake caliper 12 is provided so as to straddle the disk rotor 14, and a cylinder 16 is formed on the inner side thereof.

The cylinder 16 is connected to a master cylinder through a brake pipe (not shown), and brake oil is supplied and supplied according to a driver's operation of a brake pedal.
It is configured to be discharged. A piston 18 is slidably fitted into the cylinder 16. Accordingly, as the brake oil is supplied to and discharged from the cylinder 16 as described above, the piston 18 is moved in the direction indicated by the arrow X in FIG.
It moves in the directions indicated by 1, X2.

The outer side of the piston 18 (arrow X)
An inner brake pad 1b is disposed on one side (in one direction). That is, the inner brake pad 1b is disposed between the disk rotor 14 and the piston 18.
Therefore, when the piston 18 moves in the direction of the arrow X1, the inner brake pad 1b is pressed and urged by the piston 18 to press against the disk rotor 14.

The brake caliper 12 extends to the rear side of the outer brake pad 1a, and its tip is formed with claw portions 20a and 20b which are bifurcated. The claws 20a and 20b are configured to engage with the back surface of the outer brake pad 1a. As described above, when the piston 18 moves in the direction of the arrow X1 and the inner brake pad 1b comes into pressure contact with the disk rotor 14, the claws 20a and 20b relatively move in the direction of the arrow X2.
Move in the direction. As a result, the outer brake pad 1a is pressed and urged by the claw portions 20a, 20b, so that the outer brake pad 1a is pressed against the disk rotor 14.

Accordingly, the disk rotor 14 is sandwiched between the outer brake pad 1a and the inner brake pad 1b, and the disk rotor 14 and each of the brake pads 1a,
1b, friction is generated, and the rotation of the disk rotor 14 is braked. By performing the above operation, the disc brake device 10 generates a braking force on the vehicle. Reference numeral 22 in the figure denotes a mount for holding the brake caliper 12 movably.

Next, the disc brake pad 1 (outer brake pad 1a, inner brake pad 1b) provided in the disc brake device 10 having the above-described configuration will be described with reference to FIG. FIG. 1A is a front view of the disc brake pad 1, and FIG. 1B is a side view of the disc brake pad 1. The disc brake pad 1 is roughly composed of a pad body 2 (2a, 2a).
b) and back metal 4 (4a, 4b).

The pad body 2 (shown in satin) directly contacts the disk rotor 14 to generate a frictional force.
An abrasive, a lubricant, and a binder are mixed at a predetermined ratio. Specifically, copper (C
u) and iron (Fe) in a fibrous form, and the like. MoS ₂ , Sb ₂ S ₃ , C and the like are used as lubricants, and phenol resin and the like are used as binders. Used. The back metal 4 is made of an iron alloy or the like,
The pad body 2 is press-formed into a predetermined shape, and the pad body 2 is fixed.

In the disk brake pad 1 having the above-described structure, the present invention is characterized in that the surface of the pad body 2 is subjected to surface burning on both sides in the rotation direction of the disk rotor 14 (indicated by an arrow in FIG. 1A). It is assumed that.
In this embodiment, the hatched portion in FIG. 1A is a portion where the surface grilling is performed (hereinafter, the portion where the surface grilling is performed is referred to as a surface grilled portion 6).

As a method of performing the surface baking, for example, a method of baking with a gas burner, a method of baking by pressing against a hot plate, and the like can be considered. In the present embodiment, the surface was baked by pressing a portion corresponding to the surface baked portion 6 on a hot plate heated to 500 ° C. for about 3 minutes using a method of pressing against a hot plate and baking. The inventor conducted various experiments for examining physical characteristics of the disc brake pad 1 on which the surface-baked portion 6 was formed by performing the surface-baking as described above. As a result, it was found that by performing surface baking on the pad body 2, physical properties such as a decrease in friction coefficient, a decrease in hardness, a decrease in strength, an improvement in hydrophobicity, and the like occur in the pad body 2. . Hereinafter, the change in the physical characteristics will be described in detail.

According to the experiment of the present inventor, it has been found from the experiment of the present inventor that by performing the surface baking, the friction coefficient of the surface-baked portion 6 is reduced by about 0.03 as compared with the friction coefficients of other parts. did. As described above, the coefficient of friction is reduced by performing the surface baking.
When the surface is baked, the organic material (phenol resin or the like used as a binder) as a pad material is carbonized, and copper (Cu) or iron (Fe) mixed as an abrasive is oxidized, so that the adhesive force is reduced. It is presumed to be due to the decrease.

As described above, since the friction coefficient of the surface-baked portion 6 is reduced, the vibrating force at the time of occurrence of brake squeal can be reduced. That is, as described above, the brake squeal is generated by the friction of the pad body 2 with the disk rotor 14. The frictional force is generated at the position where the pad body 2 is dragged by the rotation of the disk rotor 14, that is, at the position on both sides of the pad body 2 (the disk rotor 1).
4 on both sides in the rotation direction). Therefore, by forming the surface baked portions 6 at both side positions of the pad main body 2 as in the present embodiment, it is possible to reduce the vibrating force that causes brake squeal, thereby preventing the occurrence of brake squeal. be able to.

According to the experiment of the present inventor, it has been found from the experiment of the present inventor that the hardness of the surface-baked portion 6 is reduced by performing the surface-baking as compared with the friction coefficient of other portions. The decrease in hardness was about 30 on the Rockwell S scale. As described above, the reason why the hardness is reduced by performing the surface baking is that the organic material (a phenol resin used as a binder, etc.) used as the pad material by performing the surface baking as described above.
Is presumed to result from carbonization.

As described above, according to the configuration of the present embodiment, the hardness of both sides of the pad body 2 can be made lower than the hardness of the central part, as in the prior art described above. The surface pressure distribution on the contact surface between the disk and the disk rotor 14 is made uniform. Therefore, the vibration characteristics can be improved (that is, the vibration can be reduced), and the occurrence of brake squeal can be suppressed.

Regarding the decrease in strength The decrease in strength observed by performing surface baking is as follows:
In particular, a decrease in tensile strength. This phenomenon is also presumed to be caused by carbonization of the organic material as the pad material by surface baking. As described above, when the tensile strength in the surface-baked portion 6 of the pad body 2 is reduced, the amount of wear generated in the surface-baked portion 6 at the time of sliding contact with the disk rotor 14 increases. Therefore, even if the disk rotor 14 slides into contact with the surface-baked portion 6, before the vibration is generated between the disk rotor 14 and the surface-baked portion 6 due to the friction, the surface-baked portion 6 is hardened.
Will be worn. Therefore, the disk rotor 14
The slidable contact portion between the and the surface grilled portion 6 does not become the point of vibration, so that the occurrence of brake squeal can also be suppressed.

Improvement of Hydrophobicity According to an experiment performed by the inventor, it has been found that by performing surface baking, the hydrophobicity of the entire pad body 2 is improved. It is considered that the hydrophobicity of the entire pad body 2 is improved by performing the surface baking on both sides of the pad body 2 for the following reasons.

That is, by performing the surface baking, an organic substance (a phenol resin or the like used as a binder) as a pad material is melted and flows in the porous pad main body 2. As is well known, an organic substance such as a phenol resin has hydrophobicity, and this organic substance is
By flowing inside, the small holes in the pad main body 2 are in a state of being buried in the organic substance. Accordingly, it is presumed that by performing the surface baking, the hydrophobicity of the entire pad body 2 is improved.

As described above, since the entire pad body 2 has a hydrophobic structure, water may intervene in the sliding contact portion between the pad body 2 and the disk rotor 14 after, for example, car washing. However, the occurrence of brake squeal can be prevented. FIG. 2 shows the results of a brake squeal test performed by the inventor. The figure shows the squeal rate when a conventional brake pad (shown as a comparative example in the figure) without surface burning is mounted, and the brake pad 1 (shown as an example in the figure) of the present example. The squeal rates are shown in comparison.

The experiment was conducted by using a passenger car having a total weight of 1800 kg and mounting the conventional brake pad and the brake pad 1 of the present embodiment on the disc brake device of the passenger car. Also,
The squeal rate was shown as a ratio of the number of occurrences of brake squeal to the total number of brakes. As shown in the figure, the squeal rate of the brake pad 1 according to the present embodiment is about 1/4 compared to the squeal rate of the brake pad of the conventional configuration. Therefore, the experimental results shown in FIG. 2 prove that the use of the brake pad 1 according to the present embodiment suppresses the occurrence of brake squeal.

On the other hand, even if the occurrence of brake squeal is suppressed as described above, it is difficult to say that the brake pad has good characteristics if the amount of pad wear increases. Therefore, the inventor also carried out an experiment for examining the amount of pad wear on the brake pad 1 according to the present embodiment. This experiment was performed simultaneously with the above-described experiment for determining the squeal rate.

As a result, the amount of pad wear of the brake pad 1 according to the present embodiment was substantially the same as the amount of pad wear generated in the conventional brake pad. in this way,
The surface hardened portions 6 having low hardness are formed on both sides of the pad body 2 so that even when the hardness of the center portion of the pad body 2 becomes relatively high, the amount of wear of the pad does not increase. It seems to be.

FIG. 5 shows the pad surface of the pad body 2 after the above-described experiment has been performed. As shown in the figure, accumulation of abrasion powder 8 was observed on the pad surface of the pad body 2 after the experiment was performed. Therefore, the pad wear amount did not increase even when the hardness at the central portion of the pad body 2 increased, because the organic carbide generated by the surface burning was deposited on the central portion of the pad body 2 to perform a lubricating action. It is estimated that this was due to the improvement in And wear powder 8
Seems to be attached to this carbide.

As described above, by forming the surface baked portion 6 on the side of the pad body 2, not only the hardness of the surface baked portion 6 of the pad body 2 but also the friction coefficient and the strength are reduced. , And changes in physical properties such as improved hydrophobicity. As a result, the excitation force can be reduced and the excitation point can be improved, and the cause of the brake noise can be reduced, so that the brake noise can be reliably prevented.

In the above-described embodiment, the surface is baked on both sides of the pad body 2, and therefore, the pad body 2 is provided with two surface baked portions 6. However, it is not always necessary to form the surface baked portions 6 on both sides of the pad body 2, and the above-described effect can be realized even if it is formed on only one of the two. At this time, the position where the surface burning is performed on the pad
It is desirable to select the front side (leading side) with respect to the rotation direction of No. 4. This is because brake squeal is likely to occur particularly on the leading side.

[0036]

As described above, according to the present invention, by performing surface baking on the side of the pad body, not only the hardness in the surface baking part of the pad body is reduced, but also the physical coefficient such as a reduction in the coefficient of friction is reduced. A change in characteristics occurs. As a result, the excitation force can be reduced and the excitation point can be improved, and the cause of the brake noise can be reduced, so that the brake noise can be reliably prevented.

[Brief description of the drawings]

FIG. 1 shows a disc brake pad according to an embodiment of the present invention, and FIG. 1 (A) is a front view and FIG.
(B) is a side view.

FIG. 2 is a diagram showing a squeal rate generated when a disc brake pad according to an embodiment of the present invention is used, in comparison with a conventional squeal rate.

FIG. 3 is a front view of a disc brake device provided with a disc brake pad according to an embodiment of the present invention.

FIG. 4 is a side sectional view of a disc brake device provided with a disc brake pad according to an embodiment of the present invention.

FIG. 5 is a view for explaining the reason why the pad wear amount does not deteriorate in the disc brake pad according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc brake pad 1a Outer brake pad 1b Inner brake pad 2, 2a, 2b Pad body 4, 4a, 4b Back metal 6 Surface burned part 8 Wear powder 10 Disc brake device 12 Brake caliper 14 Desk rotor 16 Cylinder 18 Piston 20a, 20b Claw Part 22 Mount

Claims (1)

[Claims] 1. A disk brake pad for generating a braking force by bringing a pad body into frictional contact with a disk rotor, wherein at least one side of the both sides of the pad body in the rotation direction of the disk rotor has a surface burn. A disc brake pad characterized by being performed.