JP3159008B2 - Surface pressure measuring device for friction material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a surface pressure of a friction material, and more particularly to a device for measuring a surface pressure acting on a friction material of a drum brake device and a disc brake device in a vehicle. The present invention relates to a surface pressure measuring device.

[0002]

2. Description of the Related Art In a drum brake device or a disc brake device of a vehicle, an unpleasant noise generally called brake squeal is frequently generated. In order to prevent or reduce the above-mentioned brake squeal, it is important to accurately measure the surface pressure of the friction material mounted on the brake shoe or the friction pad when the brake is operated, and to detect the fluctuation or the like. In addition, research on the braking performance of the brake device under various road conditions or climatic conditions also requires that the surface pressure acting on the brake shoes or the friction pads be correctly detected.

[0003] In general, there are two methods for measuring the surface pressure of the pressure-receiving surface: (A) a method of directly applying a strain gauge and measuring the operating pressure based on the output thereof; Measuring the surface pressure by changing the color according to the
(C) A method using a sensor sheet and the like are known. However, during the braking operation, the measurement of the surface pressure generated on the friction material of the brake shoe or the friction pad in the brake device accompanied by wear and heat generation and fluctuating by the braking operation requires the above-mentioned (B) and (C). ) Is inherently inappropriate.

[0004] Therefore, the above-mentioned (A), that is, a normal method of directly applying a strain gauge to measure the working surface pressure of a brake shoe or a friction pad is described in a perspective view of FIG. 4 and a partially enlarged front view of FIG. Description will be made with reference to a partially enlarged sectional view of FIG. In the drawing, reference numeral 10 generally indicates a brake shoe of a drum brake device. The brake shoe 10 includes a friction material or a friction lining 12 pressed against an inner peripheral surface of a brake drum (not shown) by an actuator such as a wheel cylinder, A pressing member or shoe backing metal 14 for supporting the friction material 12 is provided. As is well known in the art, the pressing member 14 generally has an arc-shaped rim 14a made of a steel material, and a reinforcement projecting in the width direction of the rim 14a, substantially perpendicularly to a substantially central portion thereof. Web (not shown).

[0005] In the friction material 12, a number of long hole-shaped recesses 16 for measuring surface pressure are arranged in two rows in the circumferential direction. A cylindrical protrusion 18 is provided in the recess 16, and a well-known strain gauge 20 is attached to a side surface of the protrusion 18. An electric wire 22 for extracting an electric variable amount of output is connected to the strain gauge 20, and the output of the strain gauge 20 extracted from the electric wire 22 is amplified by a conventional method and recorded on a recorder, and recorded by a printer. Stamped on paper.

When measuring the surface pressure acting on each part of the friction material 12, when the brake shoe 10 is pressed against the inner peripheral surface of the cooperating brake drum by a wheel cylinder (not shown) or a pressurizing device instead of the wheel cylinder, The top surface of the ridge 18 in the elongated hole 16 acts as a sensor surface to generate a surface pressure, which generates an electrical output on the strain gauge 20. Therefore, the strain gauges 2 in the many recesses 16
By measuring the output of 0, the surface pressure of each part of the friction material 12 can be known.

However, in the direct measuring method using the strain gauge 20, the brake drum is rotated with respect to the brake shoe 10, so that the sensor surface of
It is difficult to accurately measure the surface pressure because it is affected not only by the surface pressure in the direction perpendicular to the inner surface of the brake drum but also by the frictional force acting in the circumferential direction. 12 has a high temperature (300 to 400 ° C.), so that there is a problem that an error due to the high temperature occurs in the output of the strain gauge 20.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is capable of correctly detecting surface pressure without being affected by frictional force. It is a primary object of the present invention to provide an apparatus for measuring surface pressure of a material. Also, the present invention
It is another object of the present invention to provide a friction material surface pressure measurement device capable of measuring a correct surface pressure without being affected by a high temperature due to heat generated by the friction material. Furthermore, the present invention further provides a friction material surface pressure measuring device that can simultaneously measure the surface pressure at a plurality of positions of a brake shoe or a friction pad of a vehicle brake device and has high measurement efficiency. It is the purpose of.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a strain generating member mounted on a pressing member for applying a pressing force to a friction material and having a strain gauge mounted thereon, and a back surface of the friction material. A ball provided between the ball member and the strain generating member, and a cooling fluid supply
The present invention proposes a friction material surface pressure measuring device comprising a feeding device . In the present invention, the friction material
A hard pressure plate made of heat insulating material is interposed between the back of
It is preferred that the. Further, the friction material is a friction lining in a brake shoe of a drum brake device or a friction lining in a friction pad of a disc brake, and the strain generating member is attached to a back metal of the brake shoe or a plurality of locations of the friction lining. Is desirable.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to a sectional view of a main part of FIG. 1, a front view of FIG. 2, and a strain gauge output diagram of FIG. (Note that members and portions substantially the same as or corresponding to those of the conventional strain gauge use measuring device described with reference to FIGS. 4 to 6 are denoted by the same reference numerals, and redundant description is omitted.) In the cross-sectional view of FIG. 1 (cross-section along the line II in FIG. 2), the brake shoe 10 of the drum brake device is mounted on a pressing member made of a steel plate or a rim 14a of a shoe backing metal 14 with rivets, an adhesive, It comprises a friction material or friction lining 12 mounted by a fastening means.

The friction member 12 generates a braking force by pressing one side surface 12a thereof against the inner peripheral surface of a brake drum (not shown). The rim 14a in contact with the rear surface or the rear surface 12b of the friction material 12 has a plurality of rims 14 (see FIG. 1;
Are shown in the figure), and a mounting nut 2 is provided at the open end of each circular hole 24 on the shoe backing metal 14 side.
6 is fixed by welding 28 or bonding.

A measuring body 30 in the form of a bolt is screwed to the mounting nut 26 and fixed by a lock nut 32. A hole for accommodating the hollow cylindrical strain-generating cylinder 34 is formed in the shaft part 30a of the measuring unit main body 30, and an end of the strain-generating cylinder 34 facing the friction material back surface 12b is preferably made of steel. Ball 36 is secured by welding, brazing or other means. As shown in the front view of FIG. 2, the shaft portion 30 a of the measurement unit main body 30 has a shape in which a circular shaft portion is cut out by two parallel planes. A hole 38 is formed in a portion adjacent to the hole 38 in a direction perpendicular to the body axis. A pair of strain gauges 20 are affixed to the outer peripheral surface of the strain generating cylinder 34 facing the through hole 38 so as to oppose each other in diameter.

A cooling water supply pipe 40 and a cooling water discharge pipe 4 for supplying an appropriate cooling liquid, preferably cooling water, through the head 30b of the measuring section main body 30 in the internal space of the strain tube 34.
2 are provided, and a through hole 46 is formed in the head 30b to insert the electric wire 44 connected to the pair of strain gauges 20. In this preferred embodiment, a hard heat insulating material, for example, a pressure receiving plate 48 made of ceramics is interposed between the ball 36 and the back surface 12b of the friction material 12.

In the surface pressure measuring device having the above structure, a pressing device such as a wheel cylinder (not shown) is used.
When the brake shoe 10 is pressed against the inner peripheral surface of the brake drum, the friction surface 12a of the friction material 12 frictionally contacts the inner peripheral surface of the drum to generate surface pressure. (For example, 300 to 400 ° C)
become. At this time, since the cooling water is supplied from the cooling water supply pipe 40 and discharged from the cooling water discharge pipe 42 into the strain-causing cylinder 34 to which the ball 36 is attached, the strain-causing cylinder 34 is actively cooled. In addition, since the pressure receiving plate 48 made of a heat insulating material is interposed between the ball 36 and the friction material 12, heat conduction from the friction material 12 is interrupted. The strain gauge 20 has an advantage that the output characteristics hardly change due to high temperature.

When the friction member 12 is pressed against the inner peripheral surface of the brake drum, a frictional force acts on the friction member 12 in the circumferential direction of the drum. Since substantially point contact is made, the circumferential frictional force does not adversely affect the output characteristics of the strain gauge 20, and the strain gauge 20 correctly picks up substantially only the surface pressure, The output indicating the surface pressure via the electric wire 44 is recorded on a recorder (not shown) known per se, and is displayed on the recording paper of the printer. FIG. 3 shows the strain gauge 20 on the vertical axis.
Output (μst), and the horizontal axis indicates the surface pressure (kgf / c
m ² ), which is an example of a strain output diagram of the surface pressure measuring device shown in FIG.
The strain output changes almost linearly with the surface pressure, and the negative effects of high temperature and circumferential friction described above are virtually eliminated, confirming that the surface pressure measurement device is extremely reliable. Was done.

According to the preferred embodiment, since the ball 36 of the strain tube 34 is substantially in point contact with the pressure receiving plate 48, heat conduction from the friction material 12 to the strain gauge 20 is essentially required. Therefore, even if the cooling water supply pipe 40 and the cooling water discharge pipe 42 are omitted and the active cooling of the strain generating pipe 34 is omitted, the adverse effect of the high temperature is relatively small, and the ball 3
Since the influence of the frictional force acting in the circumferential direction of the drum by the point contact 6 can be eliminated, the contact pressure can be measured with an accuracy sufficient for practical reliability.

If the friction material 12 is of a certain degree of hardness, even if the pressure receiving plate 48 is omitted, the ball 36 and the friction material 1
2, the frictional heat transmitted from the friction material 12 to the strain gauge 20 via the ball 36 is small, and the effect of the frictional force acting in the circumferential direction of the drum is substantially reduced. Therefore, it is possible to secure the surface pressure measurement accuracy of a practically acceptable level.

Further, as an object for measuring the surface pressure,
A brake pad in a vehicle drum brake device and a friction pad attached to a caliper or the like of a disc brake device are the most preferable applications.In the case of the brake shoe or the friction pad, a plurality of the surface pressure measuring devices are respectively provided. By mounting, it is possible to simultaneously and efficiently detect the surface pressure generation state of each part of the brake shoe or friction pad. For example, consider measures to prevent brake squeal or detect the wear state of each part of the friction material and take measures It is extremely useful for taking a lesson.

It should be noted that the present invention is not limited to the measurement of the surface pressure of the brake shoes and the friction pads in the above-mentioned brake device, but can be widely applied to the measurement of the surface pressure of various friction materials. .

[0020]

As described above, the frictional material surface pressure measuring device according to the present invention comprises a strain-generating member attached to a pressing member for applying a pressing force to the friction material and having a strain gauge attached thereto. A ball provided between the back surface of the friction material and the strain-generating member, and a coolant supply for supplying a coolant to the inside of the strain-generating member;
Characterized in that a feeding device, a high surface pressure adversely based on the direction of the frictional force along the frictional surface of the high-temperature effects and friction material that occurs in the friction operation of the friction material to effectively eliminate accuracy At high temperatures caused by friction.
Surface pressure measurement with higher accuracy by effectively eliminating measurement errors
There is an advantage that can be performed .

In addition, by interposing a hard pressure receiving plate made of a heat insulating material between the back surface of the friction material and the ball, heat conduction from the friction material to the strain gauge can be more reliably prevented.
There is an effect that the point contact of the ball can be further ensured, and the influence of the frictional force acting in the direction along the friction surface of the friction material can be more reliably eliminated. Furthermore, the friction material, when a friction lining in friction pads of the friction lining or disk brakes, in the brake shoe of the drum brake device, the strain-generating member is mounted at a plurality of locations of the backing metal or the friction lining of the brake queue As a result, the surface pressure can be measured efficiently, which is advantageous in the measurement work.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view (in a cross section taken along line II of FIG. 2) of a main part showing a preferred embodiment of the present invention.

FIG. 2 is a front view of a measurement unit main body 30 in FIG.

FIG. 3 is a strain output diagram showing an example of a measurement result in the surface pressure measuring device shown in FIG.

FIG. 4 is a perspective view showing an example of a conventional method for directly measuring the surface pressure of a brake shoe in a drum brake device using a strain gauge.

FIG. 5 is an enlarged front view of a portion surrounded by a dotted line in FIG.

6 is a sectional view taken along the line VI-VI in FIG. 5 and viewed in the direction of the arrow.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... brake shoe, 12 ... friction material or friction lining, 14 ... pressing member or shoe backing, 14a ... rim, 2
0: strain gauge, 24: circular hole, 26: mounting nut, 30
... Measurement unit body, 30a ... Shaft, 32 ... Lock nut, 3
4 ... strain tube, 36 ... ball, 40 ... cooling water supply pipe, 42
... cooling water discharge pipe, 44 ... electric wire, 48 ... pressure receiving plate.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-54-89784 (JP, A) JP-A-5-238576 (JP, A) JP-A-5-2099641 (JP, A) 25272 (JP, U) Japanese Utility Model Application 56-74337 (JP, U) Japanese Utility Model Application Hei 5-92656 (JP, U) Japanese Utility Model Application 7-41437 (JP, U) Japanese Utility Model Utility Model 55-177989 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) G01L 5/28 G01L 1/26

Claims (3)

(57) [Claims] 1. A strain generating member attached to a pressing member for applying a pressing force to a friction material and having a strain gauge mounted thereon, a ball provided between a back surface of the friction material and the strain generating member , A coolant supply for supplying a coolant to the inside of the strain generating member.
A surface pressure measuring device for a friction material, comprising: a feeding device . 2. The heat insulation between the back surface of the friction material and the ball.
Claims characterized in that a hard pressure plate made of material is interposed
Item 2. A surface pressure measuring device for a friction material according to Item 1. 3. A drum brake device comprising : a friction material;
Friction lining or disc brake in rake shoe
The friction lining on the rake friction pad
The strain generating member is a back metal of the brake shoe or the friction.
A contractor characterized by being installed at multiple locations in the lining
The surface pressure measuring device according to claim 1.