JPH05141458A - Wear detection device for brake pad - Google Patents

Abstract

PURPOSE:To enable accurate detection of wear of a brake pad to be conducted by constructing the wear detection device of a brake pad so that a rotator provided inside a brake pad contacts a disc and rotates, and changes the conducting state between a pair of conducting terminals with this rotation when the brake pad is worn away to the extent of a fixed amount. CONSTITUTION:In a disc brake, a brake pad 20 is pressed by a disc rotor 10, gradually worn away by frictional engagement of them, and, when its wear reaches a fixed amount, an eccentric projection 33c on the front end surface of a rotating member 33 that is supported by a lining 22 and burried in the brake pad 20 becomes to expose itself. This projection 33c causes the rotating member 33 to rotate by bringing itself into contact with the disc rotor 10, and an electric conductor 33d is also rotated by this rotation and comes off the space between a pair of conducting terminals 32 making the space between a pair of conducting terminals 32 to an nonconducting state, and the wear of a lining 21 is detected, and by receiving this detection result, an alarm device 34 outputs an alarm for the wear of the lining 21 by putting the lamp thereof ON.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake pad wear detecting device for detecting wear of a brake pad.

[0002]

2. Description of the Related Art Conventionally, a brake pad wear detecting device of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 62-75143, from the back plate side of the brake pad facing the disc rotor to the lining side. Insert a non-conductive case and embed the core wire that forms the detection sensor in the same case, detect the wear of the brake pad by the disconnection of this core wire, and prohibit the operation of the starter motor of the engine based on this detection result. Alternatively, an alarm device turns on a lamp to warn the wear state.

[0003]

However, in the above-described brake pad wear detecting device, when the brake pad is pressed against the disc rotor to apply a brake even after the core wire is broken due to wear of the brake pad, the broken core wire Comes into contact with the disk rotor and the cores become conductive,
The brake pad may be detected as worn but not worn. The present invention is intended to solve the above problems, and an object of the present invention is to provide a wear detecting device for a brake pad that accurately detects the wear state of the brake pad.

[0004]

The structural feature of the present invention is that the inner peripheral surface of the brake pad facing the disc rotor is made of a non-conductive material in a cylindrical shape from the back plate side to the lining side. And a pair of conductive terminals provided on the inner peripheral surface of the case so as to face each other, and assembled on the inner periphery of the case rotatably around its axis so that the front end of the terminal is inserted into the lining. A rotating member, a projection eccentrically provided on the front end surface of the rotating member, and a rear end portion of the rotating member that penetrates perpendicularly to the axial direction, and the pair of conductive members is formed in accordance with the rotating position of the rotating member. And a conductor that makes the terminals conductive or non-conductive, and wear of the brake pad is detected by conduction or non-conductive of the pair of conductive terminals.

[0005]

With the configuration of the present invention as described above, when the brake pad is pressed by the disc rotor and is worn by a predetermined amount due to the frictional engagement between the two, the rotating member provided in the brake pad The projection eccentrically provided on the front end surface contacts the disk rotor, the rotational force of the disk rotor acts on the projection, and the projection rotates integrally with the rotating member as the disk rotor rotates. For this reason,
At the rear end of the rotating member, a conductor penetrating perpendicularly to the axial direction rotates to change between a pair of conductive terminals to a non-conductive state or a conductive state, and a brake is caused by a change in the conductive state between the conductive terminals. Pad wear is detected. Then, at the position where the rotation direction of the protrusion is orthogonal to the rotation direction of the disc rotor, the rotation force of the protrusion based on the rotation of the disc rotor is not generated, and the rotation of the protrusion and the rotation of the rotating member are stopped. As a result, the rotary member remains in this stop position even if the brake pad further wears or the rotation direction of the disc rotor changes. Therefore, the conductive state between the conductive terminals caused by the rotation of the protrusion does not further change, and therefore the result of the wear detection of the brake pad is maintained, so that accurate wear detection can always be performed.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a disc rotor 1 of a disc brake.
1 shows schematically a wear detection device 30 mounted on a brake pad 20 located close to 0. The wear detection device 30 is a case 31 that is inserted from the back plate 22 side of the brake pad 20 and partially protrudes toward the lining 21 side.
Is equipped with. The case 31 is made of a non-conductive material and has a cylindrical shape. The case 31 is fixed to the back plate 22 of the brake pad 20 by a flange portion 31 on the front side and the rear side.
a and 31b are provided, and a hole K having a cylindrical inner peripheral surface from the front end surface to the front end of the rear flange portion 31b is provided. Further, a cylindrical recess is provided on the front surface of the front flange portion 31a, and a ring-shaped recess is provided on the inner peripheral surface of the hole K near the front end of the case 31.

On the inner peripheral surface of the hole K of the case 31, a pair of conductive terminals 32 are inserted through the rear flange portion 31b.
2, the conductive terminal 32 is formed in a convex shape outward at the center of the cross section, as shown in FIG. In addition, each conductive terminal 32 has a conductor 33d to be described later between them.
In the state in which is not inserted, the distance between the terminals is shorter than the diameter of the inner peripheral surface, and when the conductor 33d is inserted, it spreads to the diameter of the inner peripheral surface to sandwich the conductor 33d. .. The conductive terminal 32 is connected to a conductive wire outside the case 31, and is connected to an alarm device 34 for alarming wear of the brake pad by lighting a lamp or the like.

The rotating member 33 includes a disk-shaped contact portion 33a made of a non-conductive material and a cylindrical rod-shaped portion 33b provided coaxially with the contact portion 33a. A protrusion 33c is provided at one location on the outer peripheral portion of the. In addition, an intermediate flange portion 33b ₁ is provided in the vicinity of the contact portion 33a of the rod-shaped portion 33b.
A conductor 33d is provided at the rear end of b through the rod-shaped portion perpendicularly to the axial direction. The rotating member 33 includes the contact portion 3
3a is fitted in a cylindrical recess on the front of the case 31, the intermediate flange 33b ₁ is inserted in a ring-shaped recess provided on the inner peripheral surface of the case 31, and the conductor 33d is opposed to the inner peripheral surface of the case 31. By being inserted between a pair of electrically-conductive terminals 32 provided as described above, it is incorporated in the case 31 so as to be rotatable in the axial direction. At this time, as shown in FIG. 2, the conductor 33d is clamped and positioned by the pressing force of the conductive terminal 32 in the concave portion at the center of the conductive terminal 32, and the rotating member 33 is in a state where the lining 21 is less worn. Is rotated by vibration or the like so that the conductor 33d is disengaged from between the conductive terminals 32 and held by the conductive terminals 32 so that the wear detecting device 30 does not malfunction. In addition, the protrusion 33c is shown in FIG.
As shown in, the brake pad 20 is provided at a position closest to the center of the brake pad 20 so as to receive the maximum rotational force from the disc rotor 10.

The operation of the disc brake wear detecting device 30 constructed as above will be described. In this disc brake, the brake pad 20 is pressed by the disc rotor 10 and is gradually worn due to frictional engagement between the two. However, the brake pad 2 is repeatedly worn due to repeated frictional engagement.
When the wear of 0 reaches a predetermined amount, a projection 33c provided eccentrically on the front end surface of the rotating member 33 is exposed on the surface of the lining 21 and contacts the disk rotor 10. Then, as shown in FIG. 4A, the protrusion 33c provided on the front end surface of the rotating member 33 rotatably attached to the case 31 moves from the rotation center Od of the disk rotor 10 due to friction with the disk rotor 10. Upon receiving the rotational force in the direction of the arrow A of the portion having the radius R ₁ , the rotary member 33 rotates integrally with the rotary member 33 in the direction of the arrow B in the direction of the arrow B around the rotational center Ok. Along with the rotation of the protrusion 33c, the conductor 33d also rotates and is disengaged from between the conductive terminals 32, whereby the conductive terminals 32 become non-conductive and wear of the lining 21 is detected. In response to this detection result, the alarm device 34 warns the wear of the lining 21 by lighting a lamp or the like.

During the rotation of the protrusion 33c, as shown in FIG.
As shown in FIG. 4, when the rotation direction of rotation of the projection 33c reaches a position orthogonal to the rotation direction of the predetermined rotation radius R ₂ portion of the disk rotor 10, the rotation of the disk rotor 10 causes no rotation force on the projection 33c. The rotational movement of the protrusion 33c stops. At this stop position, no rotational force is generated on the protrusion 33c regardless of the rotation direction of the disk rotor 10, and no rotational force is generated on the contact portion even after the protrusion 33c disappears due to wear. Therefore, the non-conducting state between the conductive terminals 32 caused by the rotation of the protrusion 33c is not further changed, and the wear detection result of the brake pad 20 is maintained, so that accurate wear detection can always be performed. Since the non-conducting state does not change, the alarm device 34 does not need to be provided with a lamp lighting holding circuit or the like.

In the above embodiment, the conductive terminal 3 is used.
2 and the conductor 33d are arranged such that the lining 21 and the conductor 33d are in a conductive state when the lining 21 is not worn, as shown in FIG.
Although the conductor 33d is rotated so as to be in a non-conductive state between them when worn, as a modification, as shown in FIG. 3, the arrangement of the conductive terminal 32 and the conductor 33d is such that the brake pad is not worn. In some cases, the two may be in a non-conducting state, and the conductor 33d may rotate to contact the conducting terminal 32 and become in a conducting state when worn.

In the above embodiment, the alarm device 34 is adapted to give an alarm by lighting the lamp or the like in response to the result of wear of the brake pad. As in the brake lining wear alarm device disclosed in Japanese Patent No. 75143, the operation of the starter motor of the engine may be prohibited in response to the result of the wear detection of the brake pad.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a wear detecting device for a brake pad according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a cross-sectional view showing a modified example of the arrangement of conductors and conductive terminals.

FIG. 4 is an operation explanatory diagram illustrating a rotation mechanism of a protrusion.

[Explanation of symbols]

10 ... Disc rotor, 20 ... Brake pad, 21 ...
Lining, 22 ... Back plate, 30 ... Wear detection device, 31 ...
Case, 32 ... Conductive terminal, 33 ... Rotating member, 33c ... Projection, 33d ... Conductor, K ... Hole.

Claims (1)

[Claims] 1. A case having a cylindrical inner peripheral surface formed of a non-conductive material is inserted from the back plate side of the brake pad facing the disc rotor toward the lining side, and the case is formed on the inner peripheral surface of the case. A pair of conductive terminals provided to face each other, a rotating member assembled on the inner circumference of the case so as to be rotatable about its axis, and having a front end portion intruding into the lining, and a biased member on the front end surface of the rotating member. A protrusion provided in mind, and a conductor penetrating perpendicularly to the axial direction at the rear end of the rotating member, and electrically connecting or disconnecting the pair of conductive terminals depending on the rotational position of the rotating member. A wear detecting device for a brake pad, comprising: a brake pad wear detecting device, wherein wear of the brake pad is detected by conduction or non-conduction of the pair of conductive terminals.