JPH1030664A - Brake disc and disc type brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the generation of uncomfortable noise during brake of a disc type brake through simple constitution without increasing the size of a device. SOLUTION: A brake disc 11 used in a disc type brake is rotated around a rotary shaft (the axle of a vehicle) 12 serving as a rotation center during running of the vehicle. During brake of the vehicle, brake pads make contact with the sides the brake disc in a manner to nip the brake disc 11 therebetween and rotation of the brake disc 11 is decelerated or stopped by a friction force. The brake disc 11 has pores 13a, 13b, 13c,... The lengths in a peripheral direction of the pores 13a, 13b, 13c,... are set in a manner not to coincide with each other. Pitches between the adjoining pores (or a distance between the pore and the pore adjoining to the pore) do not coincide with each other. By forming the pores 13a, 13b, 13c,..., the symmetrical property of the brake disc 11 is eliminated.

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 a brake disc, and more particularly to a technique for suppressing noise during braking of a disc brake.

[0002]

2. Description of the Related Art A friction type brake in a brake device mounted on a vehicle or the like usually has a friction member (brake pad) brought into contact with a rotating body (a brake disk in a disk type brake) which rotates together with a wheel. The rotation of the wheel is decelerated or stopped by the frictional force.

FIG. 3 is a view for explaining a disk brake which is one of the conventional friction brakes. The disc brake uses a brake disc 101 as shown in FIG. The brake disc 101 has a disk shape and is provided in parallel with a wheel (not shown).
The brake disc 101 rotates about the axle together with the wheels when the vehicle is running.

A brake pad 102 is provided on the side of the brake disk 101 near the outer periphery so as to sandwich the brake disk 101. Then, when the brake pedal is depressed during braking, the brake pad 102 presses and clamps the side surface of the brake disc 101 from both sides, and the rotation of the wheel is reduced or stopped by the frictional force at the contact portion.

The shape of the brake disc is shown in FIG.
In addition to a simple disk shape such as the brake disc 101 shown in FIG. 3A, a venturied type shown in FIG. 3B is known. The venturated brake disc 103 has a structure in which gaps are radially partitioned from the disc toward the outer periphery at regular intervals, and have a plurality of ventilation holes 104. Then, during traveling, the air flows through the ventilation holes 104 by rotation, and the heat generated by the friction during braking is efficiently cooled.

[0006]

However, in the case of a disc brake, unpleasant noise may occur during braking. Although the mechanism of this noise generation has not been analyzed exactly, it is caused by the fact that the brake disk 101 or 103 itself vibrates due to friction with the brake pad 102.

By the way, the conventional brake disk 101 shown in FIG. 3A has a disk shape and is completely rotationally symmetric. The conventional ventured type brake disc 103 shown in FIG. 3B has a configuration in which ventilation holes 104 of the same size are provided radially at equal intervals, which is also rotationally symmetric.

However, such an object having a symmetrical shape tends to ride a standing wave by resonating with vibration of a specific frequency. As an example, FIGS. 4 (a) and 4 (b) show the states when the standing wave of section 8 and the standing wave of section 10 are on the brake disk 101, respectively. In the figure, the standing wave is schematically represented by a broken line.

The above standing wave is generated by the brake disc 101
Or, it has a close relationship with the natural vibration frequency determined by the shape and material of 103, and once generated, does not attenuate in a short time. If the frequency of this standing wave is in the audible frequency range, it becomes noise and gives an unpleasant sensation.

The frequency of the standing wave riding on the brake disk 101 or 103 varies depending on the material of the disk and the circumferential length (ie, diameter). Therefore, if the material and the circumference of the disk are set so that the frequency of the standing wave is out of the audible frequency range, even if the standing wave rides on the brake disk 101 or 103, it should not be heard as noise.

However, the brake disc 101 or 103 is required to have a predetermined strength and light weight.
There is little freedom in selecting the material. Alternatively, if priority is given to shifting the frequency of the standing wave out of the audible frequency range, it may be necessary to select a material that sacrifices any of strength, lightness, and cost. Also, in the method of changing the circumferential length of the brake disc 101 or 103, when the disc is made smaller, there is a possibility that the braking capacity is reduced. When the disc is made larger, the workability when assembling the brake device and the space efficiency when mounting are deteriorated. In addition, the weight increases. Therefore, there is a limit in adjusting the frequency of the standing wave by changing the circumferential length of the disk.

An object of the present invention is to solve the above-mentioned problem, and to reduce unpleasant noise generated at the time of braking of a disk brake with a simple configuration without increasing the size of the apparatus.

[0013]

The brake disc used in the disc brake of the present invention has a non-rotationally symmetric shape. The non-rotationally symmetric shape is realized by providing a plurality of protrusions and the like unevenly on the outer peripheral portion of the brake disk. In the case of a ventured type brake disc, a plurality of ventilation holes may be provided asymmetrically to make the shape non-rotationally symmetric. In this case, the sizes of the plurality of ventilation holes are made uneven, or the intervals at which the plurality of ventilation holes are provided are made uneven. When eliminating the rotational symmetry of the brake disc, the center of gravity of the brake disc is positioned on the rotation axis of the brake disc.

As described above, if the symmetry of the brake disk is eliminated, it becomes difficult for a standing wave to ride when the brake disk is vibrated. Therefore, the vibration of the brake disc generated by friction with the brake pad during braking is
This is a vibration other than a standing wave and attenuates in a short time, so that noise is suppressed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of a brake disc according to one embodiment of the present invention. The brake disk 1 is provided in parallel with a wheel (not shown), and rotates together with the wheel around a rotation axis (axle of the vehicle) 2 when the vehicle runs. When the vehicle is braked, a brake pad (see FIG. 3A) provided so as to sandwich the brake disc 1 comes into contact with the side surface of the brake disc 1 and the friction force of the brake pad 1
The rotation of (ie, the wheel) slows down or stops.

A projection 3 is provided on the outer peripheral portion of the brake disc 1.
a to 3e are provided. The projections 3a to 3e are integrally formed with the disk. The circumferential lengths of the projections 3a to 3e are formed so as not to coincide with each other.
In the example shown in FIG. 1, for example, the length of each projection in the circumferential direction is formed so as to satisfy 3e>3d>3c>3b> 3a. Further, the pitch between the projections (the interval between a certain projection and a projection adjacent to the projection) does not match each other.
In the example shown in FIG. 1, for example, the pitch between the projections is 3b-
3c>3d-3e>3c-3d>3a-3b> 3a-3
e.

As described above, the brake disk 1 of the present embodiment has uneven projections 3a to 3e on its outer peripheral portion.
Are provided at non-periodic intervals, and have a non-rotationally symmetrical shape when the rotation shaft 2 is the center of rotation. However, the projections 3a to 3e are
The brake disk 1 is formed so that the center of gravity (center of mass) of the brake disk 1 is located on the rotating shaft 2. However, the circumferential length of each protrusion and the pitch between each protrusion described above are merely examples, and are not limited to these. If at least one of (1) and (2) described later is satisfied, other lengths may be used. It may be.

In the above embodiment, the projection is provided on the disk-shaped disk. However, the rotational symmetry may be broken by removing the outer periphery of the disk-shaped disk unevenly.

Next, an example in which the present invention is applied to a venturated brake disk will be described. The conventional ventured type brake disk has a structure in which radially partitioned gaps are provided at regular intervals from the inside of the disk toward the outer peripheral direction. The gap is radially partitioned in a non-rotationally symmetric manner. Each radially partitioned space is a vent hole of a venturated brake disc. Then, during traveling, the air flows through the ventilation holes by rotation, so that the heat generated by the friction during braking is efficiently cooled.

FIG. 2 is a configuration diagram of a venturated brake disk according to the present embodiment. The brake disk 11 is provided in parallel with the wheel, similarly to the configuration shown in FIG. 1, and rotates together with the wheel about the rotation shaft 12 as a center of rotation when the vehicle travels. When the vehicle is braked, a brake pad provided so as to sandwich the brake disk 11 contacts the side surface of the brake disk 11, and the friction causes the rotation of the brake disk 11 (that is, the wheel) to be reduced or stopped.

The brake disc 11 has a plurality of ventilation holes 1.
3a, 13b, 13c,. . . And the opening of each ventilation hole is located on the outer periphery thereof. Each of the ventilation holes 13a, 13b,
13c,. . . Are formed such that their circumferential lengths do not match each other. Further, the pitch between the ventilation holes (the distance between a ventilation hole and the ventilation hole adjacent to the ventilation hole) does not match each other.

As described above, the brake disc 11 is provided with the ventilation holes 13a, 13b, 13c,. . .
Are provided at non-periodic intervals, and have a non-rotationally symmetrical shape when the rotation shaft 12 is the center of rotation. However, the ventilation holes 13
a, 13b, 13c,. . . Is the brake disc 11
Is formed so that the center of gravity is on the rotation shaft 12.

Next, a description will be given of how the standing wave becomes difficult to ride on the brake disk of the present embodiment. Hereinafter, the ventured type brake disk shown in FIG. 2 will be described.

As described above, an object having symmetry (particularly, a disk-shaped object having rotational symmetry) like the shape shown in FIG. 3 (a) or (b) generates a standing wave when vibrated. Easy to ride.

On the other hand, the brake disc 11 of the present embodiment has the ventilation holes 13a, 13b, 13c,. . . Are unevenly provided to break the rotational symmetry. For this reason, a standing wave such that the entire brake disk 11 resonates is not generated. Alternatively, even if a standing wave is generated, the frequency is higher than that of the standing wave shown in FIG. 4 and is outside the audible range, so that it is not recognized as noise.

Waves (vibrations) other than the standing wave attenuate more rapidly with time than the standing wave. For this reason, even when the brake disk 11 vibrates due to friction with the brake pad during braking of the vehicle or the like, the vibration is rapidly attenuated in a short time, so that unpleasant noise is suppressed.

The ventilation holes 13a, 13b, 13
c,. . . When the rotation symmetry is broken, for example, a configuration may be used in which ventilation holes having the same length are provided at unequal intervals, or ventilation holes having different lengths are provided at equal intervals. The configuration may be any. That is, in the break disk 11,
A plurality of ventilation holes are provided so as to satisfy at least one of the conditions (1) and (2). (1) At least the shape of each ventilation hole does not match at all (2) At least the pitch between each ventilation hole does not match at all However, by providing the ventilation holes, the brake disc 11 If the center of gravity is displaced from the rotating shaft 12, an unnecessary force is applied to the rotating shaft 12 and the brake disc 11 itself during rotation.
It is necessary to provide a ventilation hole under the condition that it comes on the upper side.

Although the above description is directed to the brake disk 11 shown in FIG. 2, it is also applicable to the brake disk 1 shown in FIG. However, in the brake disk 1, there are two conditions that (1) at least the shapes of the projections do not all match, and (2) at least the pitches of the projections do not all match. By providing a plurality of protrusions so as to satisfy at least one of the above, the rotational symmetry is broken.

Further, in the above-described embodiment, the structure in which the protrusions are provided unevenly on the outer peripheral portion of the brake disk and the structure in which the vent holes are provided unevenly in the venturated type brake disk are shown. The present invention is not limited to this, and includes all configurations in which the rotational symmetry of the brake disc itself is eliminated while maintaining the center of gravity on the rotation axis.

[0030]

According to the present invention, since the brake disk used in the disk type brake has a non-rotationally symmetrical shape, it becomes difficult for the standing wave to ride on the brake disk itself, and the vibration generated by friction with the brake pad during braking. Is attenuated in a short time, and noise is suppressed. Further, the configuration can be realized without increasing the size of the brake disk, and the workability at the time of assembling and the space efficiency at the time of attachment are not deteriorated and the weight is not increased. Further, the natural vibration frequency can be widely adjusted by the shape of the projections or the ventilation holes and the number of the projections or the ventilation holes, so that it is not necessary to change the material of the brake disc itself in order to suppress noise.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a ventured type brake disk of the present embodiment.

3A and 3B are views for explaining a disk type brake which is one of conventional friction type brakes. FIG. 3 (a) is an external view of a general brake disk, and FIG. 3 (b) is an external view of a ventured type brake disk. Is shown.

FIGS. 4A and 4B are diagrams schematically showing a state in which a standing wave rides on a brake disc, and FIGS. 4A and 4B are examples in which standing waves of nodes 8 and 10 are riding, respectively.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Break disc 2, 12 Rotation axis (axle of vehicle) 3a to 3e Projection 11 Vented brake disc 13a, 13b, 13c,. . . Vent

Claims (8)

[Claims] 1. A brake disk used for a disk-type brake, wherein the shape of the brake disk is non-rotationally symmetric. 2. A brake disk used for a disk-type brake, wherein a mass distribution in a rotational direction is asymmetric. 3. The brake disk according to claim 1, wherein a plurality of protrusions are provided unevenly on an outer peripheral portion. 4. A ventilated type brake disk used for a disk brake, wherein a plurality of ventilation holes are provided asymmetrically. 5. The brake disc according to claim 4, wherein the sizes of the plurality of ventilation holes are not uniform. 6. The brake disc according to claim 4, wherein the intervals at which the plurality of ventilation holes are provided are not uniform. 7. The brake disc according to claim 1, wherein the center of gravity is on the rotation axis. 8. A disc brake comprising: a brake disc having a non-rotationally symmetric shape; and a brake pad that contacts a side surface of the brake disc during braking.