JPH0849737A - Pad structure of disc brake - Google Patents

Abstract

PURPOSE:To prevent the generation of squeal at the non-braking time by forming a slit obliquely along the rotating direction of a disc rotor from the inner diameter to the outer diameter of a pad, and specifying the pad width direction dimension of the slit. CONSTITUTION:The friction face of a pad 5 is provided with a slit 10 extended obliquely along the rotating direction of a disc rotor toward the outer diameter side 5d from the inner diameter side 5c. In the slit 10, the pad width direction dimension corresponding to the disc rotor rotating direction from the pad innermost diameter position to the outermost diameter position is made L, the ratio between the dimension from the pad centerline to the innermost diameter position of the slit and the dimension from the centerline to the outermost diameter position is X:(1-X), the distance from the rotational center to the innermost diameter position of the slit is made R1, and the distance from the rotational center to the outermost diameter position of the slit is made R2. At this time, the dimension L is set according to L>=[(R1<2>.R2<2>-R1<4>)/(X<2>.(R2<2>-R1<2>)+R1<2>))]<1/2>. Self-excited vibration generated to the pad 5 is thereby suppressed so as to prevent squeal at the non-braking time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc brake, and more particularly to a structure of a pad which is arranged to face a disc disk rotor and is pressed by the disc disk rotor.

[0002]

2. Description of the Related Art As a conventional disc brake, for example, Japanese Patent Application Laid-Open No. 1-172645 and Japanese Utility Model Laid-Open No. 62-18 are disclosed.
Some are disclosed in Japanese Patent No. 439, etc. In these, the disc rotor is integrally fixed to the wheel side,
A caliper is supported on the vehicle body side. A pair of pads are disposed on the caliper so as to face both sides of the disc rotor, and by operating the piston by hydraulic pressure, the left and right pads are pressed against the disc rotor, so that braking is exerted. .

The friction surface of the pad is provided with a slit extending from the inner diameter side to the outer diameter side of the pad.
Squeaking that occurs when the brake is operated, that is, when the pad is pressed against the disc rotor is prevented. At this time, in the invention described in Japanese Utility Model Laid-Open No. 62-18439, among the two corners formed at the boundary between the slit and the pad friction surface, the corner of the corner on the inlet side in the rotation direction of the disk rotor is used. Is chamfered to improve squeal prevention when the pad is pressed, that is, when braking.

[0004]

Even when the brake is not applied, that is, the pad is not pressed by the disc rotor,
As shown in FIG. 5, the disk rotor 50 tilts due to lateral acceleration input caused by turning of the vehicle, and the surface wobbling of the disk rotor 50 causes the disk rotor 50 to slide on the pad 51 to cause drag.

At this time, in the conventional disc brake pad 51 structure as described above, as shown in FIG. 6, when the disc rotor 50 is in sliding contact with the pad portion 51a on the inlet side in the rotational direction of the disc rotor 50, the pad 51 tries to follow the disc rotor 50, and a change occurs in the posture of the portion 51b on the outlet side in the rotation direction of the disc rotor 50, which lifts up toward the disc rotor 50 side.

Therefore, a corner portion 53 of the slit 52 on the outlet side in the rotation direction of the disk rotor 50 relatively protrudes, and a corner portion of the corner portion 53 is caught by the disk rotor 50, so that the drag force sharply increases. Excited vibration occurs, which causes a problem that abnormal noise occurs during non-braking. Particularly, in the conventional pad structure as described above, the disc rotor 5 in the slit 52 is
Since the corner of the outlet 53 on the outlet side in the 0 rotation direction is sharp, it is easily caught.

Further, since it is practically unavoidable that the pad 51 on the inlet side in the rotation direction of the disk rotor 50 sandwiching the slit 52 is worn away, it is practically impossible to avoid it.
2, the corner portion 5 on the outlet side of the disc rotor 50 in the rotation direction
3 becomes a relatively protruding state, and this also
The above phenomenon is likely to occur. Of the two corners 53 formed by the slit 52, the above-mentioned actual opening 62-1843 is used.
As described in Japanese Patent No. 9, the squeal prevention when the pad 51 is pressed with the chamfered corner portion 53 of the disk rotor 50 on the inlet side in the rotation direction is not useful for the squeal prevention during non-braking.

The present invention has been made in view of the above problems, and an object thereof is to prevent the occurrence of squeal during non-braking.

[0009]

In order to achieve the above object, the pad structure of the disc brake of the present invention is provided with a slit extending from the inner diameter side to the outer diameter side with respect to the friction surface of the pad. In the pad of the disc brake, the slit extends obliquely along the rotation direction of the disc rotor from the inner diameter position of the pad to the outer diameter position, and the slit innermost position to the pad outermost diameter position in the slit. To L is the dimension in the pad width direction corresponding to the rotation direction of the disk rotor, and the dimension from the pad center line at the pad width center to the pad innermost position and the slit pad from the pad center line. The ratio to the dimension to the outermost diameter position is X: (1-X), the distance from the disk rotor rotation center to the pad innermost diameter position of the slit is R1, and The distance to the pad outermost diameter position of the slit from Sukurota rotation center when the R2, the dimension L of the pad width direction of the slit, is characterized by being set in accordance with the following equation.

L ≧ [(R1 ² · R2 ² −R1 ⁴ ) / {X ² · (R
2 ² −R1 ² ) + R1 ² }] ^1/2

In addition to the structure described in claim 1, as described in claim 2, among the two corners formed at the boundary between the slit and the pad friction surface,
The corner of the outlet side corner in the disc rotor rotation direction is chamfered along the extending direction. In addition to the configuration described in claim 2, as described in claim 3, the chamfer is set so as to increase from the inner diameter side to the outer diameter side.

Further, in contrast to the structure described in claim 2 or claim 3, as described in claim 4, the chamfer is formed to a position closer to the back metal than the effective thickness of the pad. Characterize.

[0013]

The surface runout of the disk rotor is periodically swung in the left-right direction around the rotation axis, that is, toward the pad.
The amount of surface runout with respect to the outer diameter portion side of the pad is the largest, and the position of the outermost diameter portion of the pad is the most problematic. In addition, since the pad spring normally applies a certain amount of restraint force to the pad, the pad cannot be sufficiently escaped and dragged as the amount of surface runout increases.

During the dragging process, the dragging force is suddenly increased by being caught by the corner of the slit on the outlet side in the rotation direction. As a result, self-excited vibration is generated in the pad, which causes squeaking during non-braking. Therefore, in the present invention, in order to facilitate the occurrence of drag of the disk rotor from the inner diameter side of the pad, which has a small restraining force and the amount of surface wobbling, toward the outer diameter side, the slit is changed from the inner diameter position of the pad to the outer diameter position. Set the slit along the rotation direction of the disk rotor, that is, at the position where the inner diameter side of the slit is closer to the inlet of the disk rotor rotation direction than the outer diameter side, and extend the slit obliquely with the above inclination. ing.

Further, according to the present invention, the local dragging to the slit corner portion at the pad outer diameter side position where the pad restraining force is large and the surface wobbling amount of the disk rotor is large is from the pad inner diameter side having a smaller restraining force. By gradually or simultaneously applying the surface runout of the disc rotor, the squeal during non-braking is reduced. From the inner diameter side of the pad or at the same time, the conditions under which the contact of the surface wobbling occurs were found, and it was found that the position of the slit should be set so as to satisfy the following formula.

L ≧ [(R1 ² · R2 ² −R1 ⁴ ) / {X ² · (R2 ² −R1 ² ) + R1 ² }] ^1/2 (1)

The reason why this equation is satisfied will be described below. First,
Referring to FIG. 4, the inner diameter side end of the slit in the pad is A, the outer diameter side end of the slit is B, the distance from the center of rotation of the disc rotor to A (radius on the inner diameter side of the add) is R1, the disc is The distance from the rotation center of the rotor to B (radius on the pad outer diameter side) is R2, the length in the pad width direction from the pad innermost position to the pad outermost position in the slit is L, and the pad width direction center The ratio of the distances from B to A is (1-X): X, and the deflection angle from the point A to the point B around the disk rotor rotation center is a,
The deflection angle from the pad center line centering on the disc rotor rotation center to point A is a1, and the deflection angle from the pad center line centering on the disc rotor rotation center to point B is a2.
And

When the maximum amount of surface wobbling at the point B, which is the outermost diameter portion in the slit, is P, the maximum amount of surface wobbling at the point A, which is the outermost diameter portion in the slit, is
From the ratio of the radius from the center of the disk rotor, P ・ (R1 /
It is represented by R2). The surface runout of the disk rotor is
It is considered that a cosine curve is drawn at a predetermined position on the pad friction surface to periodically approach and depart. Therefore, the shake of the disk rotor surface at the point A position is expressed by the following equation.

(R1 / R2) · P · cos θ where θ is a deflection angle from an arbitrary position in the disc rotor rotation direction. Similarly, the runout of the disk rotor surface at the position of point B is expressed by the following equation since the phase advance from point A to point B is a. P · cos (θ + a) At this time, if the amount of surface runout at the position B is equal to or smaller than the amount of surface runout at the position A, the disk rotor is
The maximum point of surface deflection slides from the point side to the point B side (or at the same time).

This condition is expressed by the following expression. P · cos (θ + a) ≦ (R1 / R2) · P · cos θ (2) The case where the left and right values are the same in the above equation (2) is the case where they come into contact at the same time. Here, considering the case where the disk rotor surface deflection at the position of point A is the maximum, θ = π, and therefore, substituting this condition into the above equation (2) gives the following equation.

Cos a ≤ (R1 / R2) (3) On the other hand, from the geometrical conditions in FIG. 4, (R1 · cos a1) ² + (L · X) ² = R1 ² (R2 · cos a2 ^{) 2 + (L · (1} -X)) is expressed as ² = R2 ^2, the following expression from the two equations are Michibikeru.

Cos a1 = √ (R1 ² −L ² · X ² ) / R1 (4) cos a2 = √ (R ^{2 2} −L ² · (1-X) ² ) / R2 (5) The same Then, sin a1 = L · X / R1 (6) sin a2 = L · (X−1) / R2 (7) where cos a = cos (a1 + a2) = cos a1 · cos a2 − Since sin a1 · sin a2, substituting equations (4) to (7) into this equation, cos a = (√ (R1 ² −L ² · X ² ) / R1) · (√ (R2 ² −L ²・ (1-X) ² ) / R2) -X ・ (1-X) ・ L ² / (R1 ・ R2) ...... (8) This equation (8) is substituted into the above equation (3) and arranged. Then, it becomes the following formula.

(X ² · R2 ² −X ² · R1 ² + R1 ² )
・ L ² ≧ R1 ² · R2 ² −R1 ⁴ Therefore,

L ≧ [(R1 ² · R2 ² −R1 ⁴ ) / {X ² · (R
2 ² −R1 ² ) + R1 ² }] ^1/2

It is expressed as By setting the slit to a value that meets this equation, it is possible to prevent the disk rotor from being directly caught only at the corners of the slit at the pad outer diameter position where the restraining force is large. As a result, generation of abnormal noise during non-braking is reduced.

Since the equation (1) does not depend on the amount of surface wobbling, it is understood that the position of the slit can be determined without depending on the surface wobbling accuracy of the disk rotor.
Further, the abnormal noise is generated due to an increase in dragging force due to being caught by a corner of the slit. In view of this, as described in claim 2, when the corner of the corner is chamfered on the outlet side in the rotation direction of the disk rotor in which the catch occurs during non-braking, the part caught by the disk rotor becomes an obtuse angle, which causes the catch. The force is reduced, and the generation of abnormal noise during non-braking can be further reduced.

Further, by setting as described above, the chamfered portion serves as a guide and the dragging proceeds along the slit. Therefore, it is more effective to prevent abnormal noise from occurring when the movement along the slit progresses smoothly. To this end, as described in claim 3, it is smoother to deepen the chamfer from the inner diameter side toward the outer diameter side, that is, along the rotation direction of the disk rotor.

The reason for this is that, as can be seen from the above formula (1), the more the position of the slit is displaced in the disc rotor rotation direction, that is, the smaller X, the larger the above L and the greater the inclination of the slit. The chamfer at the corner of the slit on the disk rotor rotation outlet side is such that the inner diameter side is small and the chamfer is large toward the outer diameter side, and the inclination of the chamfer line is larger than that of the slit itself, and the chamfered portion is smooth. It will also have the role of a good guide.

Further, with the structure according to the fourth aspect, even if the pad on the inlet side in the disc rotor rotation direction with respect to the slit is worn, the corner contacting with the disc rotor can be maintained even if the brake is effective. It can be maintained at an obtuse angle.

[0030]

An embodiment of the present invention will be described with reference to the drawings.
In the disc brake of this embodiment, as shown in FIG.
A one-piston caliper floating disc brake will be described as an example. First, the configuration will be described. The disc rotor 1 is fixed to a wheel hub and rotates integrally with the wheel.

Reference numeral 2 is a caliper, and a body 2a is supported by a floating bracket fixed to the vehicle body through a slide pin. Thereby, the body 2a
Are movable in the axial direction of the disc rotor 1.
A cylinder 3 is formed on the body 2a, and a piston 4 in the cylinder 3 is slidable in the axial direction of the disc rotor 1.

A pair of pads 5 are arranged so as to face each other with the disc rotor 1 interposed therebetween, one pad 5a is fixed to the tip of the piston 4, and the other pad 5b is the foot 2b of the caliper 2. Is stuck to. In addition,
6 is a dust boot and 7 is a piston seal. The piston seal 7 is made of rubber and holds the hydraulic pressure in the cylinder 3 and also the brake pad 5 and the disc rotor 1.
Has the function of adjusting the gap between.

As shown in FIG. 2, the friction surface of the pad 5 is provided with a slit 10 extending obliquely along the rotation direction of the disk rotor 1 from the inner diameter side 5c to the outer diameter side 5d. . The slit 10 is formed by determining the dimension L in the roller rotation direction between the position of the innermost diameter portion and the position of the outermost diameter portion based on the equation (1) described in the section of the action.

For example, the distance from the rotation center of the disk rotor 1 to the inner diameter side 5c of the pad 5 is 105 mm, and the distance from the rotation center of the disk rotor 1 to the outer diameter side 5d of the pad 5 is 140 mm. For
The dimension from the pad center line P to the outermost diameter position of the slit 10 is equal to the dimension from the pad center line P to the innermost diameter position of the slit 10 (that is, X in the equation (1) is 0.5). Value), the following equation is obtained by substituting in equation (1).

L ≧ 84.7 mm. Therefore, in accordance with the above formula, 42.3 to the left and right from the pad center line P, respectively.
The slit 10 may be formed such that the outermost diameter position and the innermost diameter position of the slit 10 are located at positions separated by 5 mm. By setting the position and the inclination of the slit 10 in this way, when the disk rotor 1 wobbles during non-braking, the disk rotor 1 simultaneously contacts the entire corner portion of the slit 10.

The corner of the slit 10 on the outlet side in the rotation direction of the disk rotor 1 is chamfered 11 along the corner. The chamfer 11 is provided deeper than the pad effective thickness D to the position of the back metal 20. Further, the chamfer 11 is set so as to continuously increase from the inner diameter side 5c of the pad 5 toward the outer diameter side 5d. This chamfer 11 is, for example,
If the offset in the rotation direction of the disc rotor 1 from the pad center line P at the 11th position of the chamfer is set to 0.45, L ≧ 86.1 from the equation (1), and 86.1 mm is distributed to the left and right at 55:45. , The inner diameter side is 38.75 mm from the pad center line P, and the outer diameter side is 4 from the pad center line P
Chamfer 11 is carried out so that the position is 7.35 mm.

In the disc brake having the above structure, the piston 4 is pushed toward the disc rotor 1 by the hydraulic pressure in the cylinder 3 generated by the braking operation of depressing the brake pedal at the time of braking, and one pad 5a of the one pad 5a is pressed. The friction surface is pressed against one side of the disc rotor 1. At the same time, the same pressure acts on the bottom of the cylinder 3 to push the foot 2b of the caliper 2 toward the disc rotor 1 and the friction surface of the pad 5b on the side opposite to the piston 4 to the disc rotor 1.

As a result, the disc rotor 1 and the pad 5
A braking force is generated by the frictional force between them, and the slit 10 prevents squeaking. When the brake pedal is released and the pressure in the cylinder 3 disappears, the rubber piston seal 7 that was strongly pressed against the piston 4
The piston 4 returns to the state before the operation due to the force of returning to the original shape. As a result, the left and right pads 5 that have been crimped to the disc rotor 1 are pulled back by the amount of deformation of the piston seal 7, and a gap is formed between the pad 5 and the disc rotor 1 to prevent the drag of the brake.

At this time, the disk rotor 1 has a predetermined surface wobbling accuracy due to its mounting accuracy, and periodically shakes toward the pad 5 side following the rotation of the wheel. When the vehicle is traveling straight ahead, the contact between the disk rotor 1 and the pad 5 due to the surface wobbling can be avoided by the initial setting of the gap between the disk rotor 1 and the pad 5. However, when a lateral acceleration is input, such as when the vehicle turns, the lateral force causes the disk rotor 1 to collapse, and the disk rotor 1 collapses and the disk rotor 1 swings to cause the disk rotor 1 to fall. A temporary drag occurs between the pad 5 and the pad 5. It should be noted that the above-mentioned surface wobbling becomes maximum once every 360 ° rotation with respect to a predetermined position, and dragging occurs at that time.

At this time, in the prior art, since the corner of the slit 10 on the outlet side in the rotation direction of the disc rotor 1 was sharp,
At the corner of the slit 10 corner on the outer diameter side 5d where the binding force is large,
The disk rotor 1 in which dragging has occurred is locally caught with a predetermined catching force, and abnormal noise is generated. In the present embodiment, as described above, the disc rotor 1
Even if drag is generated between the pad 5 and the friction surface of the pad 5, the surface of the disc rotor 1 that has run-out is simultaneously contacted with the entire corner portion of the slit 10 on the outlet side in the rotation direction of the disc rotor 1, so that abnormal noise is reduced. Become.

Since the corner of the corner is chamfered 11,
The contact portion with the disc rotor 1 at the corner has an obtuse angle, the catching force due to the catching of the disc rotor 1 is reduced, and further abnormal noise is effectively prevented.
Actually, using a pad having a slit at the above position, it was confirmed that the noise during non-braking was reduced.

In the above-described embodiment, the entire surface of the slit 10 on the rotation outlet side of the disk rotor 1 is set so that the surface of the disk rotor 1 that is surface-run comes into contact at the same time, but the slit 10 extends. The angle of the direction may be set to fall from the above-mentioned position so that the surface of the disk rotor 1 which is surface-running gradually hits from the inner diameter side 5c of the slit 10.

Even in this case, it is possible to prevent the surface run-out of the disk rotor 1 from directly contacting the outer diameter portion of the corner of the slit 10 which is most affected by the generation of abnormal noise, thereby reducing the occurrence of abnormal noise. . Further, in the above embodiment, the chamfering of the corners 1
Although 1 is performed linearly, as shown in FIG. 3, chamfering 11 may be performed in a curved shape with a predetermined R. In this case, the center of R is set closer to the back metal 20 side than the effective thickness of the pad.

Although the chamfer 11 position is set to be deeper than the effective thickness of the pad 5, it may be set to a position shallower than the effective thickness of the pad 5. In the above embodiment, the chamfer 11 is set deeper than the effective thickness of the pad 5 is
Even if the pad 5 portion on the inlet side in the rotation direction of the disc rotor 1 with respect to the slit 10 is worn, as long as the pad 5 portion does not become the effective thickness or less, that is, as long as the brake works effectively, This is to maintain the contact portion at an obtuse angle.

Therefore, when the chamfered position is set to a position shallower than the effective thickness of the pad 5, the squeal preventing effect during non-braking is reduced while the brake is effectively operating. Further, among the corners formed at the boundary between the pad friction surface and the slit, the corner side on the inlet side in the disk rotor rotation direction may be chamfered to prevent squeal during braking.

[0046]

As described above, in the disc brake pad structure of the present invention, the local dragging of the slit position at the outer diameter side position where the restraining force is large is gradually reduced from the inner diameter side where the restraining force is small. Alternatively, at the same time, by bringing the surface run-out of the disk rotor into contact with the disk rotor, it is possible to reduce the occurrence of abnormal noise during non-braking.

At this time, by adopting the structure as described in claim 2, the catch between the corner formed at the boundary between the slit and the pad friction surface and the disc rotor is reduced, Furthermore, there is an effect of reducing the generation of abnormal noise during non-braking. Further, by adopting the structure as set forth in claim 3, the movement of the drag by the disc rotor from the inner diameter side to the outer diameter side in the slit can be smoothly performed, and further, during non-braking. There is an effect that the generation of abnormal noise can be reduced.

Further, by adopting the structure as described in claim 4, even if the pad portion on the inlet side in the disc rotor rotation direction with respect to the slit is unevenly worn, the corner portion of the slit and the disc rotor are separated from each other. It is possible to keep the reduction of catching.

[Brief description of drawings]

FIG. 1 is a side view showing a disc brake of an embodiment according to the present invention.

FIG. 2 is a diagram showing a friction surface of a pad according to an embodiment of the present invention.

FIG. 3 is a diagram showing another example of chamfering according to the embodiment of the present invention.

FIG. 4 is a diagram for explaining the formula (1) of the present invention.

FIG. 5 is a diagram showing a disc rotor tilting.

FIG. 6 is a diagram showing how a pad follows a disc rotor.

[Explanation of symbols]

 1 Disc rotor 2 Caliper 4 Piston 5 Pad 10 Slit 11 Chamfer 20 Back metal P Pad center line D Pad effective thickness

Claims (4)

[Claims] 1. A disc brake pad having a slit extending from the inner diameter side to the outer diameter side with respect to the friction surface of the pad, wherein the slit extends from the inner diameter position of the pad toward the outer diameter position. The dimension in the pad width direction corresponding to the disc rotor rotation direction from the pad innermost diameter position to the pad outermost diameter position in the slit, which extends diagonally along the rotation direction of the disc rotor, is L, and the pad width direction The ratio of the size of the slit from the center line of the pad, which is the central position, to the innermost pad position of the slit and the size of the slit from the centerline to the outermost pad position of the slit is X:
(1-X), where R1 is the distance from the disk rotor rotation center to the pad innermost diameter position of the slit, and R2 is the distance from the disk rotor rotation center to the pad outermost diameter position of the slit, A disc brake pad structure, wherein a dimension L in the pad width direction is set according to the following equation. L ≧ [(R1 ² · R2 ² −R1 ⁴ ) / {X ² · (R2 ² −R1 ² )
+ R1 ² }] ^1/2 2. Among the two corners formed at the boundary between the slit and the pad friction surface, the corner of the exit side corner in the disc rotor rotation direction is chamfered along its extending direction. The pad structure for a disc brake according to claim 1, wherein the pad structure is a disc brake pad structure. 3. The pad structure for a disc brake according to claim 2, wherein the chamfer is set so as to increase from the inner diameter side toward the outer diameter side. 4. The pad structure for a disc brake according to claim 2, wherein the chamfer is formed to a position closer to the back metal than the effective thickness of the pad.