JPH10141407A - Wear detector for brake pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wear detector for a brake pad which is not broken when a detection part comes into contact with a rotor and can be used repeatedly when wear of the brake pad is detected. SOLUTION: This wear detector is constituted in such a manner that a detection rod 13 provided with a metallic rod main body 20 and a tip contact part 21 which is provided in a tip part of the rod main body 20, comes into contact with a rear plate 8 of a brake pad 6 and is insulated, functions as a slide contact, a guide cylinder 11, in which the detection rod 13 is fitted and inserted in such a manner that it can advance and retract, makes a main guide cylinder 17 function as a fixed contact by providing a tip cylindrical member 18 made of an insulation material at a tip of the metallic main guide cylinder 17, and a limit of wear of the brake pad 6 is detected by opening the mutual connection of the contacts when an advance amount of the detection rod 13 exceeds a predetermined amount in accordance with the progress of wear of the brake pad 6.

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 provided in a brake device and capable of detecting that the wear of the brake pad has reached a predetermined amount.

[0002]

2. Description of the Related Art A disc brake device mounted on a vehicle such as an automobile has a predetermined amount of brake pad wear so that the brake pad pressed against a rotor can be replaced promptly when the wear reaches a limit. A device equipped with a brake pad wear detecting device capable of detecting the reaching has been developed.

As an apparatus for detecting wear of a brake pad, for example, a conductive wire is fixedly mounted on a brake pad so as to come into contact with a rotor when the wear of the brake pad reaches a predetermined amount. Various types have been developed to detect that the wear of the brake pad has reached a predetermined amount due to a current leak from the conductive wire to the rotor or a disconnection of the conductive wire due to contact with the rotor (actually). See JP-A-4-88542 and JP-A-7-4939.

[0004]

However, in the above-mentioned conventional wear detecting device, when the wear of the brake pad is detected,
The conductive wire, which is the detector, is damaged by contact with the rotor and cannot be reused.When replacing the brake pads, the wear detector itself must be replaced, which increases the cost of replacing the brake pads. There was a problem that it would.

The present invention has been made in view of the above circumstances, and there is provided a brake pad wear detecting device which can be used repeatedly without detecting the brake pad from being damaged by contact with the rotor when the wear of the brake pad is detected. It is an object of the present invention to provide a brake pad that is worn down to its limit and replaces only the brake pad to reduce the pad replacement cost.

[0006]

According to a first aspect of the present invention, there is provided a brake pad wear detecting device for detecting wear of a brake pad. A guide tube that is disposed opposite to the plate and is mounted on a pad support member, a detection rod that is inserted into the guide tube and supported to be able to advance and retreat with respect to the back plate, and is mounted on a base end side of the guide tube. A conductive rod biasing spring pressed between the cap and the detection rod and biasing the detection rod in the direction of the back plate, wherein the guide cylinder is provided at a distal end of the conductive main guide cylinder. The detection rod is provided with an insulated distal end cylindrical member through which the detection rod penetrates. The detection rod has a conductive rod main body and an insulating rod attached to the front end of the rod main body and in contact with the back plate. A tip end abutting part, and sliding on the inner peripheral surface of the guide cylinder along with the reciprocating operation of the detection rod supported on the outer peripheral part of the rod main body, the rod urging spring and the rod main body, A conductive contact member for electrically connecting the main guide cylinder to the main guide cylinder; connecting external electrodes to the main guide cylinder and the rod biasing spring, respectively; When the rod advances beyond a predetermined amount, the contact member moves from the main guide cylinder to the distal end cylinder member, and the electrical connection state between the rod body and the main guide cylinder via the contact member is changed. It is characterized in that it is configured to shut off.

Further, in the brake pad wear detecting device according to the present invention, a base ring portion locked on an outer periphery of a distal end tubular member of the guide tube and a distal end locked on an outer periphery near a distal end of the detection rod. A dust boot having a ring portion and a bellows tube portion connecting the base ring portion and the distal end ring portion may be provided.

The brake pad wear detecting device according to the present invention has the same structure as the above brake pad wear detecting device, and further includes a guide pad interposed between the pad support member and the guide cylinder. A spacer for adjusting the mounting position of the cylinder along the direction in which the detection rod moves forward and backward may be provided.

The brake pad wear detecting device according to the present invention having the above-described structure is made by paying attention to the fact that the movement stroke of the brake pad in the brake device increases as the wear of the brake pad progresses. It is. That is, the detection rod supported by the guide cylinder so as to be able to advance and retreat is pressed at its distal end against the back plate of the brake pad by the urging force of a rod urging spring that is press-fitted on the base end side of the guide cylinder. It moves forward and backward with respect to the guide cylinder following the brake pad. Therefore, the amount of advance of the detection rod from the guide cylinder increases with the progress of wear of the brake pad.

[0010] Further, the guide tube has a structure in which an end tube member made of an insulating material is attached to the end of a conductive main guide tube.
The main guide cylinder is connected to an external electrode and functions as, for example, a fixed contact that is energized to a cathode. On the other hand, the detection rod has a conductive rod main body connected to an external electrode via a rod urging spring and is energized as, for example, an anode, and a contact member provided on the rod main body includes the main guide cylinder and the tip. Since it moves with the inner peripheral surface of the cylindrical member in contact, it functions as a sliding contact. Therefore, the guide cylinder and the detection rod function as a stroke-type switch that opens the contact when the advance amount of the detection rod becomes equal to or greater than a predetermined value. By setting the dimensions of the guide cylinder and the detection rod in advance so as to correspond to the movement stroke of the brake pad when worn to the limit, it is possible to accurately detect that the brake pad has been worn to the limit. be able to.

Since the detection rod is provided in a non-contact manner with the rotating body against which the brake pad is pressed and detects the wear of the brake pad, there is no possibility of the detection rod being damaged by contact with the rotating body.

Further, if the structure around the detection rod which advances and retreats from the guide cylinder following the advance and retreat of the brake pad and the tip of the guide cylinder where the detection rod enters and exits is covered by dust boots, it is possible to detect the guide cylinder and the detection cylinder. It is possible to prevent foreign matter that inhibits the electrical connection state with the rod from entering the guide cylinder.

Further, if a structure is provided which is provided between the pad support member and the guide cylinder and adjusts the mounting position of the guide cylinder along the direction of movement of the detection rod, the brake pad It is possible to easily adjust the allowable movement amount of the detection rod until it is detected that the wear has reached the limit only by changing the dimensions of the spacer.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a brake pad wear detecting device according to the present invention will be described below in detail with reference to the drawings. FIGS. 1 to 3 show an embodiment of a brake pad wear detecting device according to the present invention. FIG. 1 is a longitudinal sectional view of the brake pad wear detecting device. FIG. 2 is a longitudinal sectional view of the brake pad wear detecting device, showing a detection state of the brake pad in a worn state to the limit, and FIG. 3 is a front view of a pad support member to which the wear detecting device is attached.

The wear detecting device 1 for a brake pad according to this embodiment is a disk brake device 3 for a vehicle that generates a braking force by pressing a brake pad 6 against a disk-shaped rotating body (rotor) 5 that rotates integrally with a wheel. When the wear of the brake pad 6 reaches a predetermined amount, the wear of the brake pad 6 is detected.

As shown in FIG. 1, the brake pad 6 has a lining portion 7 having a predetermined thickness pressed against the surface of the rotating body 5 and a back plate 8 made of a metal plate fixedly mounted on the back surface of the lining portion 7. In this configuration, hanging portions (not shown) formed on both sides of the back plate 8 are supported by a caliper body 10 as a pad supporting member so as to be able to advance and retreat toward the rotating body 5. The pressing force of a piston (not shown) provided on the rear plate 8 is received by the back plate 8 and pressed against the rotating body 5.

The wear detecting device 1 includes, specifically, a guide tube 11 mounted on a caliper body 10 which is a pad supporting member at a position facing the back plate 8 of the brake pad 6, and a guide tube 11 inside the guide tube 11. A detection rod 13 inserted into the brake pad 6 and supported so as to be able to advance and retreat toward the back plate 8 of the brake pad 6; and a metal rod bias for projecting the detection rod 13 from the guide cylinder 11 and biasing the detection rod 13 toward the back plate. And a spring 15.

The guide tube 11 is provided with a distal end tubular member 18 of an insulating material which is attached to the distal end of a metallic main guide tube 17 and through which the detection rod 13 penetrates. The main guide cylinder 17 has a flange-like flange 1 at the base end of the cylinder 17a.
7b, and the cylindrical body 17a is the caliper body 1
0 is screwed into a female screw portion 10b provided in a detection device mounting hole 10a formed through the flange portion 17a.
b is positioned and fixed to the caliper body 10 by abutting the end face 10 c of the caliper body 10. The distal end cylindrical member 18 has a cylindrical shape having the same inner diameter as the cylindrical body 17a, and is connected to a distal end of the cylindrical body 17a.
And a rod supporting portion 18b having a cylindrical shape smaller in diameter than the guide portion 18a.

The detection rod 13 is made of a metal rod body 20, a tip contact part 21 of an insulating material which is attached to the tip of the rod body 20 and contacts the back plate 8 of the brake pad 6, And a metal contact member 23 supported on the outer peripheral portion of the rod body 20 via a spring member 22 made of metal. The rod body 20 is provided with a distal end cylindrical member 18.
And a first flange portion 20a serving as a seating portion of the rod urging spring 15 at a position near the base end of the rod body 20.
And a second flange portion 20b which forms a groove for accommodating the contact member 23 between the first flange portion 20a and the first flange portion 20a. The groove between the first and second flange portions 20a, 20b regulates the movement of the detection rod 13 in the axial direction with respect to the contact member 23 and functions as a holding portion for the spring member 22. .

The spring member 22 urges the contact member 23 outward in the radial direction, and keeps the contact member 23 in contact with the inner peripheral surface of the guide cylinder 11. The rod body 20 and the contact member 23 are electrically connected. The contact member 23 slides on the inner peripheral surface of the guide cylinder 11 with the movement of the detection rod 13 due to the urging force of the spring member 22 and the position regulation by the first and second flange portions 20a and 20b. Move.

In the case of this embodiment, the rod biasing spring 15 is configured as a compression coil spring, and an insulating cap 25 screwed to the base end of the guide cylinder 11 and a first part of the rod body 20. And presses the detection rod 13 in a direction to advance from the guide cylinder 11 so that the tip of the detection rod 13 contacts the back plate 8 of the brake pad 6. ing.

A dust boot 29 is provided on the distal end side of the distal end tubular member 18. The dust boot 29 is related to a base ring portion 29a locked on a groove 18c formed on the outer periphery of the distal cylindrical member 18 and a groove 20c formed on the outer periphery near the distal end of the detection rod 13. The front end ring portion 29b to be stopped and the bellows tube portion 29c connecting between the base end ring portion 29a and the front end ring portion 29b are integrally formed of synthetic rubber or resin material having insulation and oil resistance. This prevents the rod body 20 that enters and exits from the distal end cylinder member 18 from being contaminated by foreign matter, and prevents foreign matter from entering the guide cylinder 11.

From the bottom of the insulating cap 25 on which the rod biasing spring 15 is seated and the flange portion 17b of the main guide tube 17, lead terminals 27 and 28 for conduction connected to external electrodes (not shown) are drawn out. Have been. Each of the lead terminals 27 and 28 is formed of a metal plate or the like having excellent conductivity. The lead terminal 27 extending from the bottom of the insulating cap 25 is electrically connected to the rod biasing spring 15 at the inner bottom of the insulating cap 25. The lead terminal 28 pulled out from the flange portion 17b of the main guide cylinder 17 is connected to the flange portion 17 by appropriate means such as screwing or spot welding.
b and is electrically connected.

In the brake pad wear detecting device 1 of this embodiment, the main guide cylinder 17 is used as a cathode and the rod biasing spring 15 is used as an anode to conduct electricity through the above-described lead terminals 27 and 28. By detecting the conductive state or the non-conductive state, it is detected whether or not the wear of the lining portion 7 of the brake pad 6 has reached a limit. For example, when the brake pad wear detecting device 1 is attached to the disc brake device 3 with the brake pad 6 in an unworn state, as shown in FIG. Is in a minimum state, and the main guide cylinder 17 of the cathode and the detection rod 13 of the anode are electrically connected via the contact member 23 and are in a conductive state. In this case, an external detection unit (not shown) detects that the wear of the brake pad 6 has not yet reached the limit through this conduction state.

Then, as the wear of the brake pad 6 progresses and the advance amount T of the detection rod 13 accompanying the wear of the brake pad 6 exceeds a predetermined value, as shown in FIG.
The contact member 23 is moved from the main guide cylinder 17 to the distal end cylinder member 18.
When the electrical connection between the main guide cylinder 17 and the rod body 20 via the contact member 23 is interrupted and the electrical connection is made non-conductive, the external detection unit (not shown) Reaching the limit is detected via a non-conducting state.

The brake pad wear detecting device 1 having the above-described structure is made by paying attention to the fact that the movement stroke of the brake pad 6 in the brake device increases as the wear of the brake pad 6 progresses. That is,
Detection rod 13 supported by guide cylinder 11 so as to be able to move forward and backward
The distal end of the brake pad 6 is moved by the urging force of a rod urging spring 15 press-fitted on the base end side of the guide cylinder 11.
, And moves back and forth with respect to the guide cylinder 11 following the brake pad 6. Therefore, the amount of advance of the detection rod 13 protruding from the guide cylinder 11 increases as the wear of the brake pad 6 progresses.

The guide tube 11 has a structure in which an insulating end tube member 18 is attached to the end of a metal main guide tube 17, and the main guide tube 17 is energized as a cathode and functions as a fixed contact. When the metal rod body 20 is energized as an anode through the rod urging spring 15, the contact member 23 provided on the rod body 20 is connected to the main guide cylinder 17 and the tip cylinder member 18. It functions as a sliding contact because it moves while being in contact with the inner peripheral surface of the.

Therefore, the guide cylinder 11 and the detection rod 1
3, when the amount of advance of the detection rod 13 is equal to or more than a predetermined value, it functions as a stroke type switch that opens a contact, and the amount of advance of the detection rod 13 when the contact is opened is
By setting the dimensions of the guide tube 11 and the detection rod 13 in advance so as to match the movement stroke of the brake pad 6 when the brake pad 6 is worn to the limit, the brake pad 6 can reach the limit. Wear can be accurately detected.

Since the wear of the brake pad 6 is detected without contact with the rotating body 5 against which the brake pad 6 is pressed, when the wear of the brake pad 6 is detected,
There is no possibility that the detection unit is damaged by contact with the rotating body 5. Therefore, when the brake pad 6 is worn to its limit, if only the brake pad 6 is replaced, the brake pad 6 can be repeatedly used for detecting the wear of the brake pad 6 without replacing the wear detecting device. Can be suppressed at low cost.

In the ordinary disc brake device 3, as shown in FIG. 3, the brake pad 6 is removed from the caliper body 10 in the direction of the arrow (a) and replaced.
When the brake pad 6 is replaced, the detection rod 13 of the wear detecting device 1 is pushed back by a finger so as not to hinder such replacement work of the brake pad 6. Therefore, the mounting position of the wear detecting device 1 of the present invention is set near the upper edge of the caliper body 10 and in the vicinity of the cylinder portion 10b, as shown in the figure, so that the detecting rod 13 can be easily pushed back. .

The periphery of the detection rod 13 which advances and retreats from the guide cylinder 11 following the advance and retreat of the brake pad 6 and the tip end of the guide cylinder 11 where the detection rod 13 enters and exits are covered by a dust boot 29. It is possible to prevent foreign matter that inhibits the electrical connection between the tube 11 and the detection rod 13 from entering the guide tube 11,
The desired detection performance can be maintained for a longer period.

In the above embodiment, the main guide cylinder 1
7, rod body 20, contact member 23, rod biasing spring 1
Although 5 is made of a metal having conductivity, it may be made of a material other than metal, for example, a hard resin material having a surface plated with conductive material.

In the above embodiment, the main guide cylinder 17
Of the caliper body 10 serving as a pad support member was brought into direct contact with the end face 10c of the caliper body 10. However, a spacer may be provided between the end face 10c and the flange portion 17b to adjust the mounting position of the guide tube 11 along the direction in which the detection rod 13 moves. If such a spacer is used, the allowable movement amount of the detection rod 13 until it is detected that the wear of the brake pad 6 has reached the limit can be easily adjusted only by changing the thickness dimension of the spacer. For example, even when the thickness dimension of the lining portion of the brake pad 6 is changed according to the type of vehicle or the like, it is possible to easily and quickly respond only by changing the spacer.

Further, in the above embodiment, the case where the disk brake device is provided is shown. However, the brake pad wear detecting device of the present invention can be applied to a drum brake device.

[0035]

As described above, according to the brake pad wear detecting device of the present invention, a rod urging spring in which a detecting rod supported by a guide cylinder so as to be able to move forward and backward is press-fitted on the base end side of the guide cylinder. The tip portion is pressed against the back plate of the brake pad by the urging force, and moves forward and backward with respect to the guide cylinder following the brake pad. Therefore, the amount of advance of the detection rod from the guide cylinder increases with the progress of wear of the brake pad. Further, the guide tube is
An insulative tip tube member is provided at the tip of the metal main guide tube, and the main guide tube functions as a fixed contact that is energized as a cathode. On the other hand, in the detection rod, a metal rod body is energized as an anode through a rod urging spring, and a contact member provided on the rod body contacts an inner peripheral surface of the main guide cylinder and the tip cylinder member. From moving in a state where
Functions as a sliding contact. Therefore, the guide cylinder and the detection rod function as a stroke-type switch that opens the contact when the advance amount of the detection rod becomes equal to or greater than a predetermined value. By setting the dimensions of the guide cylinder and the detection rod in advance so as to match the movement stroke of the brake pad when the brake pad has worn to the limit, it is possible to accurately detect that the brake pad has worn to the limit. be able to.

Since the wear of the brake pad is detected in a non-contact manner with the rotating body against which the brake pad is pressed, when the wear of the brake pad is detected, the detecting portion may come into contact with the rotating body and be damaged. There is no at all. Therefore, when the brake pad is worn to the limit, if only the brake pad is replaced, the wear detecting device can be used repeatedly for detecting the wear of the brake pad without replacing, and the replacement of the brake pad can be reduced inexpensively. be able to.

Further, if the surroundings of the detection rod which advances and retreats from the guide cylinder following the advance and retreat of the brake pad and the tip of the guide cylinder where the detection rod enters and exits are covered with dust boots, the detection of the guide cylinder and the detection It is possible to prevent a foreign substance that interferes with the electrical connection state with the rod from entering the guide cylinder, and to maintain desired detection performance for a longer period of time.

Further, if a spacer is provided between the pad supporting member and the guide cylinder to adjust the mounting position of the guide cylinder along the direction of movement of the detection rod, the brake pad is provided. It is possible to easily adjust the allowable movement amount of the detection rod until it detects that the wear of the brake pad has reached the limit only by changing the dimensions of the spacer. Even when the thickness dimension or the like is changed, it is possible to easily and quickly respond only by changing the spacer.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a brake pad wear detection device according to an embodiment of the present invention, showing a detection state of an unworn brake pad.

FIG. 2 is a longitudinal sectional view of a brake pad wear detecting device according to an embodiment of the present invention, showing a detection state of a brake pad worn to its limit.

FIG. 3 is a front view of a pad supporting member to which a brake pad wear detecting device is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wear detection device 3 Disc brake device 5 Rotating body (rotor) 6 Brake pad 7 Lining part 8 Back plate 10 Pad support member (Caliper body) 10c End face 11 Guide cylinder 13 Detection rod 15 Rod biasing spring 17 Main guide cylinder 17b Flange Part 18 Tip cylindrical member 20 Rod body 21 Tip contact part 22 Spring member 23 Contact member 25 Insulating cap 27, 28 Lead terminal

Claims (3)

[Claims] 1. A brake pad wear detecting device for detecting wear of a brake pad, comprising: a guide tube disposed on a pad support member, the guide tube being opposed to a back plate of the brake pad, and being fitted into the guide tube. A detection rod which is supported so as to be able to advance and retreat with respect to the back plate, and which is press-fitted between the detection rod and a cap attached to the base end side of the guide cylinder to urge the detection rod in the direction of the back plate. A conductive rod urging spring, wherein the guide cylinder is provided with an insulated distal end tubular member which is attached to a distal end of the conductive main guide cylinder and through which the detection rod passes. A conductive rod main body, an insulating front end contact portion attached to the front end portion of the rod main body and abutting against the back plate, and a reciprocating operation of the detection rod supported on the outer peripheral portion of the rod main body. To The main guide is configured to slide along the inner peripheral surface of the guide cylinder, and to include the rod urging spring and a conductive contact member for electrically connecting the rod body and the main guide cylinder. External electrodes are connected to the cylinder and the rod urging spring, respectively, and when the detection rod advances by a predetermined amount or more due to wear of the brake pad, the contact member moves from the main guide cylinder to the distal end cylinder member. A brake pad wear detecting device, wherein the electrical connection between the rod main body and the main guide cylinder via the contact member is interrupted. 2. A base ring portion that locks on the outer periphery of a distal end tubular member of the guide cylinder, a distal end ring portion that locks on an outer periphery near the distal end of the detection rod, and the base ring portion and the distal end ring. The wear detecting device for a brake pad according to claim 1, further comprising a dust boot having a bellows tube portion connected to the portion. 3. A spacer interposed between said pad support member and said guide cylinder for adjusting a mounting position of said guide cylinder along an advancing / retreating direction of said detection rod. Item 3. The wear detecting device for a brake pad according to Item 1 or 2.