JP3160123B2 - Disc brake pad used for ventilated rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pad for a disk brake used for a ventilated rotor, and more particularly to a pad provided with a slit effective for preventing low-frequency noise called dynamic grown.

[0002]

2. Description of the Related Art A disc brake presses pads on both sides of a rotor which rotates in conjunction with a wheel to be braked, brakes the rotor by friction between the pad lining and the rotor, and brakes the wheels via the rotor. It is a brake to do.

The friction with the pad lining causes the rotor to become hot due to frictional heat during braking. The ventilated rotor is configured to suppress a rise in the temperature of the rotor, and is configured as illustrated in FIGS. 4 and 5. FIG. 4 is an overall perspective view, and FIG. 5 is a partial plan view.

[0004] In the ventilated rotor 1, a large number of air passages 2 are formed, the outer end of which in the radial direction is opened on the peripheral surface of the rotor, and the inner end of which is opened outside the rotor. As shown in FIG. 5, the rotor becomes thinner on both sides of the air passage 2, and the rigidity in the thickness direction of the rotor becomes weaker. In the position off the wind path,
Since fins 3 connecting both side surfaces of the rotor are formed,
The rigidity in the thickness direction of the rotor is large.

In such a ventilated rotor (hereinafter simply referred to as a rotor), as the number of braking increases, the rotor temperature rises and the rotor thermally expands accordingly.
The expansion amount differs between the air passage 2 and the fin 3 and is large in the air passage 2. That is, in the rotor, the outer wall of the air passage 2 expands more than the fin 3 due to frictional heat. For this reason, when braking is performed in this state, the pressure applied to the outer wall of the greatly bulged air path 2 becomes larger than the pressure applied to both sides of the fin 3, and the friction work on both sides of the air path 2 is reduced on both sides of the fin 3. Larger than that at By repeating this, the rotor wears more on the outer wall of the air passage 2, and when the rotor is cooled, minute irregularities equal to the pitch of the fins 3 are generated on the side surface of the rotor. In a rotor having a height (thickness) difference of about 1.7 μm on one side of the rotor in the direction of the rotor axis of the unevenness, a characteristic low frequency called Dynamic Groan (hereinafter simply referred to as “Grone”) during braking is used. Generates noise. The frequency f (Hz) of this noise is given assuming that the vehicle speed is V (km / hr, the rotor is directly connected to the wheel), the tire diameter of the wheel is D (m), and n is the number of fins (usually 25 to 37). , F = nV /
It is represented by 3.6πD.

The reason that the vibration having the same period as the pitch of the fins 3 of the rotor is generated is that the unevenness equal to the pitch of the fins 3 of the rotor continuously enters the pad during braking, and a brake torque vibration is generated. This is because it becomes an exciting force. Due to these phenomena, a new rotor with no irregularities does not cause any growth, and a rotor that has irregularities due to its use has a large size during cooling when the irregularities are large, and a growth occurs when the temperature of the rotor rises with use. The experimental result that it disappears has been obtained.

FIG. 6 is a graph showing an experimental result in a state where the unevenness of the rotor changes with the temperature. It can be seen that the unevenness of the rotor decreases as the temperature rises.

As described above, various types of slits are formed in the lining of the pad, which becomes high in temperature together with the rotor due to braking, in order to discharge abrasion powder and water and to avoid cracking due to thermal expansion. Is being done.

FIG. 7 illustrates a general pad 6 in which a lining 4 is provided with a slit 5 in the radial direction of the rotor. 7 is a backing metal. When the slit is provided in this manner, the lining at the edge of the slit can be cooled by air passing through the slit, in addition to discharging the wear powder and releasing the thermal expansion of the lining.

Other shapes of the slit 5 formed in the lining 4 include the shapes shown in FIGS. 8 to 10 described in Japanese Patent Publication No. 38-24474 and those described in Japanese Patent Application Laid-Open No. 51-12166. 11 shape, 52-948
No. 3 discloses the shape shown in FIG. Although various such slits have been seen in the past, none of them was formed in connection with a grone.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pad having a slit which is used for a rotor to prevent the occurrence of a groon.

[0012]

SUMMARY OF THE INVENTION According to the present invention, two slits are formed in a lining, each of which intersects near one radial end of a rotor and are inclined with respect to the radial direction of the rotor, and the intersection of both slits and the rotor diameter of the lining are formed. A disk brake pad used for a ventilated rotor characterized in that the distance from one end in the direction is made smaller than 1/3 of the width of the lining in the radial direction of the rotor. .

[0013]

According to the investigations made by the present inventors, in the conventional pad lining having a slit in the radial direction of the rotor as shown in FIG. 7, as the use progresses, the edge and the peripheral portion of the slit and other parts are removed. There is a difference in the amount of wear between each part. When this was measured, as shown in FIG.
It is known that the thickness of the inner portion 4b becomes thicker (shown by + in FIG. 13) and the thickness of the inner portion 4b becomes thinner (shown by-). The thinner portion of the inner part 4b shows a substantially circular pattern. When there is no slit, the lining has an elliptical shape spread over the entire surface of the lining. Further, even if a rotor having irregularities due to the above-described reason is used, it is difficult to generate a grown when the pad is new. From this, the present inventors,
The above-mentioned pattern generated on the lining surface due to wear of the pad lining was considered to be related to the occurrence of the grown.

Such a pattern is generated because when the lining generates heat during braking, the peripheral portion 4a of the lining 4 and the edge of the slit 5 are cooled, and the temperature of the inner portion 4b becomes relatively high. As shown exaggeratedly in FIG. 14, the inner portion 4b expands, wears due to strong friction with the rotor, abrasion proceeds, and when braking is stopped and the temperature drops, the inner portion 4b is dented as shown in FIG. is there. Therefore, at the time of braking when the rotor and the lining are cold, the contact between the rotor and the lining becomes stronger at the edge of the slit and at the peripheral portion 4a than at the inner portion 4b.

In order to investigate this, the present inventors measured the temperature of each lining location and examined the relationship between the temperature and the state of occurrence of the grone. The temperature was measured because the partial strength of the contact between the pad and the rotor could not be measured. Therefore, the temperature was higher in the part where the contact was strong than in the weak part, so the strength was determined by measuring the temperature. .

As shown in FIG. 16, the temperature measurement part of the lining is the lower part (shown by a black circle) near the slit 5 of the peripheral part 4a and the center (shown by a white circle) of the inner part 4b. The measured temperatures of both parts in the graph are also indicated by black circles and white circles.
When braking is repeated about 15 times, the temperature rises to about 120 ° C., and during this time, the temperature of the peripheral portion 4a is higher, and a grown occurs. When braking is further repeated, the temperature rises, but the temperature inside rises, and the grone stops.

From this, it is considered that one condition of the occurrence of the groun is that the peripheral portion of the lining and the edge of the slit strongly hit the rotor (this is referred to as edge contact). That is, the walls on both sides of the air passage 2 are recessed, and the fins 3
It is considered that a lone occurs when a lining protruding from the rotor comes into contact with a lining having a recessed inner portion.

From the above, it is considered that the necessary and sufficient conditions for the occurrence of the grown are that (1) the rotor has irregularities having a pitch corresponding to the fin pitch, and (2) the lining is in contact with the rotor.

Next, the exciting force for generating the grone was examined, and it was found that the fluctuation of the frictional force was the exciting force.
To determine the excitation force, the friction force itself or the braking torque applied to the rotor may be measured. (The friction force is obtained by dividing the torque by the operating radius of the rotor. However, this is the same.)
The torque was measured because it was easy to measure. The following phenomena were observed in this measurement. That is, each time one fin passes through the pad, torque vibration is generated, and its size is 40 kgcm at the maximum. Since the sum of the braking torque of the inner pad and the outer pad is measured, it is 20 kgcm for one pad.

FIGS. 17 and 18 show this situation.
As shown in FIG. 18, when the edge of the slit 5 higher than the concave inner portion 4b of the lining 4 passes through the protruding fins (shown by A to E) of the rotor, as shown in FIG. In each of the positions A to E, a vibration torque of 20 kgcm is generated in the outer pad 6 and the inner pad 6 ', and a total vibration torque of 40kgcm is applied to the pad at the edge of the slit.

FIG. 1 shows a state of a vibrating force at a portion of the inclined slit 5 formed in the lining 4. The magnitude F of the torque acting on the point 10 at the edge of the slit 5
Acts in a direction perpendicular to the rotor diameter 8 passing through the point 10,
Since the torque F _P acting strongly on the lining acts at right angles to the slit 5, component perpendicular to the rotor diameter 11 passing through the center of the pad which F _X component parallel to the rotor diameter 11 F _Y
And a rotor diameter 11 and a point 10 passing through the center of the pad.
The angle between the rotor diameter 8 through the phi, when the inclination angle of the slit 5 and theta, the magnitude of the perpendicular component F _P into the slit is represented by the following formula.

F _P = F cos (90−θ + φ) (1)

It is component F that causes the pad to grown.
_X , and its size is represented by the following equation.

[0024] _{F X = F P sin θ =} Fcos (90-θ + φ) sin θ (2)

The torque component F _Y parallel to the rotor diameter 11 is

F _Y = F _P cos θ = F cos (90−θ + φ) cos θ (3)

It is considered that F _Y hardly contributes to the occurrence of a grone. The size of the F _X is significantly reduced to about 3kgcm whereas was 20kgcm For conventional slit shown in FIG.

Further, since the slit is inclined, a plurality of projections (fins are assumed to be linearly formed in the radial direction of the rotor) of the rotor hit the edge of the slit at the same time. As before, the torque increase due to the next convex portion hitting the edge of the slit will start before the torque increase due to one convex portion hitting the edge of the slit is completed, and the torque increase is intermittent. do not become. That is, the action of the convex portion pressing the lining is smoothed, and the strong pressing force unlike the conventional slit in FIG. As a result, a glow is less likely to occur.

[0029]

FIG. 3A shows an example in which two slits 5, 5 intersecting at an intersection 9 at the center of the outer periphery of the lining are provided so as to be inclined toward both side edges. As mentioned above, the slits 5, 5
Is inclined, the effect of the convex portion of the rotor pressing the edge of the slit during braking to generate a grown is significantly weakened.

FIG. 3B is a view in which the intersection 9 of the two slits 5 and 5 is shifted from the center of the outer circumference, and FIG. 3C is a view in which the two slits 5 and 5 are shifted from the center of the outer circumference to the inner corner. 3D, the intersection 9 of the slits 5, 5 is shifted from the center of the outer periphery, and FIG. 3E is the intersection 9 of the two slits 5 inside the outer periphery of the lining. This is an example of the entry.

In the slit of the shape E in FIG.
It has been found that as the length a into the inside of the lining becomes larger with respect to the width L of the lining, the rate of occurrence of the grone increases as shown in Table 1 (intersection positions are indicated by the length of a). The growth rate of 5% is considered to be practically satisfactory, so it is impossible if a ≧ L / 3.

[0032]

[Table 1]

The intersection 9 of the two slits that intersect is
3A to 3E, all are provided on the outer circumferential side of the lining in the rotor radial direction. Conversely, the same effect can be obtained by providing the lining on the end of the lining on the rotor shaft side.

In the example shown in FIG. 6 of Japanese Utility Model Laid-Open Publication No. 52-79483, the distance between the intersection of the slit and one end of the lining in the rotor radial direction is determined in the same manner as in the present invention. Although the shape changed to be smaller than 1/3 of the width has substantially the same effect in preventing the growth, it is not suitable for mass production in processing and cannot be adopted.

[0035]

[Table 2]

Table 2 shows the rate of occurrence of the grone of the lining in which the slits having the shapes of the present invention shown in FIGS. 3A to 3E are formed (at the time of 1600 braking, 1% or less is rounded off). Good grades. In addition, Table 2 shows the conventional rotor provided with a slit in the radial direction of the rotor and the conventional one provided with one inclined slit shown in FIG. 11, but the results were poor.

In any of the above cases, the exciting force applied to the lining is small because the slit is inclined.

[0038]

As for the pad of the disc brake used in the ventilated rotor of the present invention, the characteristics of a rotor having minute irregularities on the side surface and a pad in which the inner portion of the lining is recessed by friction with the rotor were investigated. As a result, a pad that hardly generates a grone is obtained, and the contact between the convex portion formed by the fin extending in the radial direction of the rotor and the edge of the slit is dispersed to smooth the excitation force caused by the contact. Was able to be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a vibrating force acting on an edge of a slit.

FIG. 2 is a diagram showing a situation in which an exciting force acting on an edge of a slit is smoothed.

FIG. 3 is a front view of a pad showing examples of slit shapes A to E.

FIG. 4 is a perspective view illustrating a rotor.

FIG. 5 is a partial plan view of a rotor.

FIG. 6 is a diagram showing the relationship between the temperature of the rotor and the amount of unevenness on the side surface.

FIG. 7 is a perspective view of a conventional pad having a slit.

FIG. 8 is a front view of a lining showing the shape of a conventional slit.

FIG. 9 is a front view of a lining showing the shape of a conventional slit.

FIG. 10 is a front view of a lining showing a shape of a conventional slit.

FIG. 11 is a front view of a lining showing the shape of a conventional slit.

FIG. 12 is a front view of a lining showing a conventional slit shape.

FIG. 13 is a front view of a pad showing a lining state of the lining.

FIG. 14 is a side view of the pad showing an expanded state of the lining when the temperature rises.

FIG. 15A shows the lining when cooled
-A sectional drawing.

FIG. 16 is a diagram showing the rise and fall of the rotor temperature during braking and the situation of occurrence of a grone.

FIG. 17 is a schematic side view showing a contact state between the rotor and the lining.

FIG. 18 is a schematic diagram showing a braking torque applied at this time.

[Explanation of symbols]

 Reference Signs List 1 ventilated rotor 2 air path 3 fin 4 lining 4a peripheral part 4b inner part 5 slit 6, 6 'pad 7 back metal 8 rotor diameter 9 intersection of slits 10 point 11 rotor diameter

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kanamesuke Sasaki 5-4-1-7 Higashi, Hanyu-shi, Saitama Prefecture Akebono Brake Industry Co., Ltd. (72) Inventor Yasuo Shoji 5-4-Higashi Higashi, Hanyu-shi, Saitama No. 71 Akebono Brake Industry Co., Ltd. Development Headquarters (56) References Japanese Utility Model Sho 52-79483 (JP, U) Japanese Utility Model Sho 60-16027 (JP, U) (58) Field surveyed (Int. . ^7, DB name) F16D 49/00 - 69/04

Claims (1)

(57) [Claims] 1. A lining is formed with two slits intersecting in the vicinity of one end in the radial direction of the rotor, each slit being inclined with respect to the radial direction of the rotor, and the distance between the intersection of both slits and one end of the lining in the radial direction of the rotor is determined. A disc brake pad used for a ventilated rotor, characterized in that the width of the lining is made smaller than 1/3 of a radial width of the rotor.