JPS60205302A - Sensor for temperature and degree of wear of brake - Google Patents

Abstract

PURPOSE:To provide both functions for detecting the wear limit of brake linings and for detecting the abnormal temp. rise of a brake fluid by providing a heat sensitive element in a movable metallic piece which is movable to press the piston in a brake cylinder. CONSTITUTION:A sensor 11 for temp. and degree of wear having a heat sensitive element 18 is installed into a movable metallic piece 21, which is movable to press a piston 4 moving on wear of brake linings 1, 1a, in the position where said sensor contacts with the brake fluid 5 and piston 4 in a brake cylinder 3. A contact 16 is held in contact with a coil spring 15 fixed to an external lead- out terminal 14. The element 18 is connected in series between the terminal 14 and a metallic case 12 and therefore the abnormal temp. rise of the fluid 5 can be detected. On the other hand, the piece 21 is moved downward by a coil spring 20 when the piston 4 arrives at a limit position on wear of linings 1, 1a. The top end of the spring 15 is then detached from the contact 16 and the terminal 14 is electrically opened from the case 12, by which the wear limit of the linings 1, 1a is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in brake safety devices for automobiles, railway vehicles, etc., and is applied to brake fluid temperature detection and brake lining wear limit detection. This relates to temperature and wear sensors.

Conventional Structure and Problems Therein FIG. 1 shows a cross-sectional view of a disc brake equipped with a conventional brake lining wear limit sensor, and FIG. 2 shows an enlarged cross-sectional view of the vicinity of this sensor. In Fig. 1, 1, 1a are brake linings, 2, 2
a is a backing metal; when the piston 4 in the cylinder 3 moves due to the hydraulic pressure of the brake fluid 6, the rotor 6 is sandwiched between the brake linings 1 and 1a from both sides, and the friction force generated at the contact surface causes A braking action occurs. Therefore, the sensor 7 in the brake lining 1 (or 1a)
If this is installed, when the brake lining 1 wears down due to friction with the rotor 6, the tips of the brake pads will also be scraped off, and this can be used to detect the wear limit of the brake lining 1. .

Next, details of detecting the wear limit of the brake lining 1 will be explained with reference to FIG. In Fig. 2, 8 is a metal wire;
In the 9ft case, 10 is an external leader line, which constitutes a sensor connection. This sensor 7 is embedded in the brake lining 1 via the metal backing 2, so when the brake lining 1 wears out and is scraped from the initial position to the limit position B, the sensor 7 is also scraped off and the metal is removed. Wire 8 is disconnected. At this time, the resistance of the sensor 7 seen from the external lead wire 10 changes from zero to infinity, and the wear limit of the brake lining 1 can be detected.

However, this sensor only detects the wear limit of the brake lining and has the disadvantage of being disposable.

On the other hand, from the safety aspect of the brake system, we are trying to prevent paper lock (a condition in which the brake fluid becomes abnormally hot, causing air bubbles to form inside the brake fluid and making the brakes ineffective), which occurs when the brakes are used continuously, especially on downhill slopes. In order to prevent this, there is a strong demand for a sensor that can also detect abnormal temperature rises in brake fluid.

OBJECTS OF THE INVENTION The present invention aims to provide a temperature and wear degree sensor that has both the functions of detecting the wear limit of brake linings and detecting abnormal temperature rises of brake fluid. It has a heat-sensitive element for detecting an abnormal temperature rise in the liquid, and a movable metal piece that presses the piston in the brake cylinder,
When the piston moves due to wear of the brake lining, the metal movable piece is structured to fall off the piston, and at this time, the contact integrated with the metal movable piece separates from the coil spring fixed to the external lead terminal and generates electricity. It is constructed with a mechanism that also detects the wear limit of the brake lining by opening the brake lining.

DESCRIPTION OF EMBODIMENTS FIG. 3 shows an embodiment of the present invention. In Figure 3, 1
Reference numeral 1 denotes a temperature and wear degree sensor according to the present invention, which is installed in a position in the brake cylinder 3 so as to come into contact with brake fluid 5 and piston 4.Next, the temperature and wear degree sensor according to the present invention is FIG. 4, which is an enlarged sectional view, will be explained. A heat-sensitive element 18 (for example, a thermistor) that detects the temperature of the brake fluid 5 is installed in a vertically movable metal movable piece 21 that presses the piston 4 that moves due to wear of the brake lining, and heat is applied to the vicinity of the heat-sensitive element 18. It is filled with a resin 22 having excellent conductivity. One lead wire of the heat-sensitive element 18 is soldered 24 to the metal movable piece 21, and the other lead wire is soldered 23 to the contact 16 attached to the metal movable piece 21 via an insulator 19. be done. Further, the contact 16 is connected to the second coil spring 16 fixed to the external lead terminal 14, so that when the metal movable piece 21 is pressing the piston 4, electricity e is applied to the external lead terminal 14.

connected. Furthermore, the metal movable piece 21 is electrically connected to the metal case 12 by the first coil spring 20 and is given a force to press the piston 4 . The sliding surface between the side surface of the metal movable piece 21 and the metal case 12 is sealed with a seal material 17 so that the brake fluid 5 does not enter inside. Also, 13.14
are an insulator and a metal plate, respectively.

Next, the operating principle will be explained. In the brake temperature/wear sensor 11 according to the present invention, the tip of the metal movable piece 21 contacts the piston 4 inside the brake cylinder 3, the metal movable piece 21 is lifted by the piston 4, and the contact point 18 is connected to the outside. It is in contact with a second coil spring 16 fixed to the extraction terminal 14. At this time, since the heat-sensitive element 18 is connected in series between the external lead terminal 14 and the metal case 12, it is possible to detect the abnormal temperature upper layer of the brake fluid 6. On the other hand, as the brake lining 1.1a wears out, the piston 4 moves leftward from the initial position C, and when it reaches the limit position, the metal movable piece 21
is moved downward by the first coil spring 2°. Here, the tip position of the second coil spring 16 when it is free is the contact point 16.
The external lead terminal 14 and the metal case 12 are electrically opened when the brake lining 1.1 is located in the L direction from the position of
A wear limit of 1L can be detected.

Effects of the Invention As explained below, the humidity and wear level sensor of the present invention has the functions of detecting both brake fluid temperature and brake lining wear level with a single sensor.
It also has the characteristic that it is not disposable and can be used semi-permanently. Furthermore, since it is a normally closed contact system, if there is a break at any point inside or outside the sensor, the condition will be the same as when the brake lining is worn out, and conversely, if there is a short circuit, the thermistor will act as a heat-sensitive element. If an element having a negative resistance-temperature characteristic is used, the brake fluid will be in the same state as when it reaches an abnormal temperature, and has a feature of having a fail-safe function. Moreover, it has an extremely simple configuration and can be provided at low cost.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a disc brake equipped with a conventional brake lining wear limit sensor, Fig. 2 is an enlarged sectional view of the vicinity of this sensor, and Fig. 3 is a sectional view of a disc brake with a temperature and wear degree sensor according to the present invention. 1.11L Brake lining, 3 Cylinder, 4
・ Piston, 6 Brake fluid, 6 Rotor, 11 Temperature, wear sensor, 12 Metal case, 14 External lead terminal, 15 Second coil spring, 16 Contact, 18 Heat sensitive element, 20 First coil spring , 21 Metal movable piece.

Claims (1)

[Claims] A heat-sensitive element for detecting the temperature of brake fluid is installed within a movable metal piece that presses a piston that moves due to wear of the brake lining, and one lead wire of the heat-sensitive element is connected to the metal movable piece. , the other lead wire is attached to a contact attached to the metal movable piece through an insulator, and the metal movable piece is electrically connected to the metal case by a first coil spring and has a force that presses the piston. and the contact point is a second one fixed to an external lead terminal.
When the metal movable piece moves into the metal case by a predetermined amount or more by the coil spring, it is electrically connected to the external lead terminal, and conversely, the metal movable piece moves into the metal case by a predetermined amount.
A brake sensor temperature and wear sensor having a structure in which the contact point and the second coil spring are separated when the sensor is moved out of the metal case (7).