JPH0134767Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a brake temperature and wear degree sensor used as a brake safety device for automobiles, railway vehicles, etc. It detects abnormal temperature of brake fluid and detects the wear limit of brake lining. It is applied to detection.

Structure of Conventional Example and Its Problems FIG. 1 shows a cross-sectional view of a conventional disc brake equipped with a brake lining wear limit sensor, and FIG. 2 shows an enlarged cross-sectional view of the vicinity of this sensor. In FIG. 1, reference numerals 1 and 1a are brake linings, and 2 and 2a are backing metals. When the piston 4 in the brake cylinder 3 is moved by the hydraulic pressure of the brake fluid 5, the rotor 6 is moved from both sides to the brake lining 1, 1a, and a braking action occurs due to the frictional force generated at the contact surface.
Therefore, if the sensor 7 is installed in the brake lining 1 or 1a, when the brake lining 1 is worn out due to friction with the rotor 6, the sensor 7
Since the tip of the brake lining 1 is also being shaved off, the wear limit of the brake lining 1 can be detected using this fact.

Next, details of detecting the wear limit of the brake lining 1 will be explained with reference to FIG. 2. In FIG. 2, 8 is a metal wire, 9 is a case, and 10 is an external lead wire, which constitute the sensor 7. 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 A to the limit position B, the sensor 7 is also scraped together with the metal wire 8. The wire breaks. 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 that it is disposable.

On the other hand, from the safety perspective of the brake system, it is necessary to prevent vapor 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. Therefore, there is a strong demand for the development of a sensor that can also detect abnormal temperature rises in brake fluid.

Purpose of the invention The present invention was devised in view of the above points, and provides a brake 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. This is what I am trying to do.

Structure of the invention The structure of the invention has a heat-sensitive element for detecting an abnormal temperature rise in the brake fluid, and a metal movable piece that presses the piston in the brake cylinder, and the piston moves due to wear of the brake lining. The structure is such that the metal movable piece slides off from the piston when the metal movable piece is moved, and at this time, the flat metal contact that integrates the metal movable piece contacts the metal case and electrically shorts the brake lining. It is constructed with a mechanism that also detects the wear limit of.

DESCRIPTION OF EMBODIMENTS FIG. 3 shows an embodiment of the present invention, with the same numbers assigned to the same parts as described above. In Figure 3, 11
is a sensor according to the present invention, and is installed in the cylinder 3 at a position where it comes into contact with the brake fluid 5 and the piston 4.

Next, FIG. 4, which is an enlarged sectional view of the sensor according to the present invention, will be explained. First, a heat-sensitive element 18 (for example, a thermistor) for detecting 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 1. The vicinity thereof is filled with a resin 22 having excellent thermal conductivity.
Further, 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 to a flat metal contact 16 attached to the metal movable piece 21 via an insulator 19. It is attached 23. Further, the flat metal contact 16 is electrically connected to the external lead terminal 14 installed on the insulated terminal plate 13 by a compression coil spring 15, and the metal movable piece 21 is connected by another compression coil spring 20. It is electrically connected to the metal case 12. here,
The spring force of the compression coil spring 15 is transferred to the compression coil spring 2.
By making the spring force larger than 0, the metal movable piece 21 is always pressed downward and pressed against the piston 4. Also, brake fluid 5
The sliding surface between the side surface of the metal movable piece 21 and the metal case 12 is sealed with a sealing material 17 so that the metal movable piece 21 does not enter the inside. The sensor 11 according to the present invention is constructed in this way.

Next, the principle of operation will be explained. In the sensor 11 of the present invention, the tip of the metal movable piece 21 contacts the piston 4 in the cylinder 3, the metal movable piece 21 is lifted by the piston 4, and the flat metal contact 16 is connected to the metal case. It is installed at a distance from 12. At this time, since the heat-sensitive element 18 is connected in series between the external lead terminal 14 and the metal case 12, an abnormal temperature rise in the brake fluid 5 can be detected. On the other hand, as the brake lining 1 (or 1a) wears out, the piston 4 moves leftward from the initial position C shown in FIG. It moves downward due to the biasing force. As a result, the flat metal contact 16 comes into contact with the metal case 12, and the external lead terminal 14 and the metal case 12 are electrically short-circuited, so that the wear limit of the brake lining 1 can be detected.

Effects of the Invention As explained above, the temperature and wear sensor of the present invention has the functions of detecting the temperature of brake fluid and the degree of wear of the brake lining with a single sensor. It also has the characteristic that it is not disposable and can be used semi-permanently.

In addition, since the contact is provided inside the metal case and is a single flat metal contact, the contact part is reliable and reliable.Furthermore, since the electrical connection is configured with a coil spring, the metal movable piece Sufficient durability can be obtained even with repeated movements.
Moreover, it has the advantage of being extremely simple in structure and can be provided at low cost.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional disc brake equipped with a brake lining wear limit sensor, and Figure 2 is an enlarged cross-sectional view of the vicinity of this sensor.
FIG. 3 is a cross-sectional view of a disc brake with a temperature and wear sensor according to the present invention, and FIG. 4 is an enlarged cross-sectional view of the vicinity of the temperature and wear sensor according to an embodiment of the present invention. 1, 1a... Brake lining, 3... Brake cylinder, 4... Piston, 5... Brake fluid, 11... Temperature, degree of wear sensor, 12... Metal case, 14... External lead-out terminal, 15, 20 ……
Coil spring, 16... Flat metal contact, 18...
...Heat-sensitive element, 19...Insulator, 21...Metal movable piece.

Claims (1)

[Scope of utility model registration request] A heat-sensitive element for detecting the temperature of brake fluid is installed inside a movable metal piece that presses a piston in a brake cylinder 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. one, and the other lead wire is attached to a flat metal contact attached to the metal movable piece through an insulator in a metal case, and the flat metal contact and the metal movable piece are connected to each other. The former is electrically connected to the external extraction terminal and the latter is electrically connected to the metal case by separate coil springs, and at least one of the coil springs has a structure that presses the metal movable piece against the piston. Brake temperature and wear sensor.