JPH0562248B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used for brake safety devices for automobiles, railway vehicles, etc., and is used to detect abnormal temperature of brake fluid and detect wear limit of brake lining. This relates to a degree sensor.

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 cylinder 3 is moved by the hydraulic pressure of the brake fluid 5, the rotor 6 is moved from both sides to the brake linings 1 and 1a. The braking action occurs due to the frictional force generated at the contact surfaces. Therefore, if the sensor 7 is installed in the brake lining 1 (or 1a), when the brake lining 1 wears out due to friction with the rotor 6, the tip of the sensor 7 will also be scraped off. The wear limit of the brake lining 1 can be detected using this.

Next, details of detecting the wear limit of the brake lining 1 will be explained with reference to FIG. In Figure 2,
8 is a metal wire, 9 is a case, and 10 is an external lead wire, which constitute the sensor 7. Sensor 7 is backing money 2
Since the metal wire 1 is embedded in the brake lining 1 via the metal wire 1, 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 and the metal wire 8 is broken. 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, we are trying to prevent vapor lock (a condition in which the brake fluid becomes ineffective due to air bubbles forming inside due to abnormal temperature rise) that occurs when the brakes are used continuously, especially on downhill slopes. Therefore, 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 brake temperature and wear degree sensor that has both the functions of detecting the wear limit of a brake lining and detecting an abnormal temperature rise of brake fluid.

Configuration of the Invention In order to achieve the above object, the configuration of the present invention includes a heat-sensitive element for detecting an abnormal temperature rise in brake fluid, a movable body that presses a piston in a brake cylinder, and a movable body that presses a piston in a brake cylinder. The movable body is structured to fall off the piston when the piston moves due to wear, and at this time, the movable contact housed in the movable body separates from the fixed contact and becomes electrically open, thereby limiting the wear limit of the brake lining. It is configured with a detection mechanism.

DESCRIPTION OF EMBODIMENTS FIG. 3 shows an embodiment of the present invention. In FIG. 3, reference numeral 11 denotes a sensor according to the present invention, which is fixed to the cylinder 3 at a position within the brake fluid 5 so as to come into contact with the piston 4.

Next, FIG. 4, which is an enlarged sectional view of the sensor according to the present invention, will be described. In FIG. 4, one electrode of a heat-sensitive element 12 (for example, a Melf-type glass-encapsulated thermistor) that detects the temperature of the brake fluid 5 is electrically connected to a movable contact 17 by a first spring 14. The other electrode is in contact with the inner bottom surface of the bottomed cylindrical movable body 13. Furthermore, the movable contact 17 provided at the opening of the movable body 13 is connected to a collar provided on itself and an insulating cylinder 15 fixed to the inner surface of the movable body 13.
It is pulled out from inside the movable body 13 so as not to extend beyond a specified length to the outside of the movable body 13 by the flange portion. Further, the fixed contact 22 which also serves as an external lead-out terminal is insulated from the metal case 19 by two insulators 23 and 20 and an O-ring 21, and is fixed to the case 19 via a metal plate 24. Here, the fixed contact 22 is placed at a position where it normally contacts the movable contact 17 arranged opposite to it, but where the movable contact 17 does not come into contact when the brake linings 1 and 1a are worn. Furthermore, the second spring 18
is installed between the metal plate 24 and the upper surface of the movable body 13, thereby electrically connecting one electrode of the heat-sensitive element 12 and the case 19 via the movable body 13, the second spring 18, and the metal plate 24. At the same time, the movable body 13 is pressed against the piston 4. The other electrode of the heat sensitive element 12 is electrically connected to the movable contact 17 via the first spring 14 . Note that the sealing material 16 prevents the brake fluid 5 from entering the inside of the case 19.

Next, the operating principle will be explained. The sensor 11 according to this embodiment is movable because the tip of the movable body 13 contacts the piston 4 in the cylinder 3 and the movable body 13 is lifted by the piston 4 when the brake linings 1 and 1a are not worn. Contact 17
and the fixed contact 22 are in contact with each other. Therefore, since the heat-sensitive element 12 is connected in series between the fixed contact 22 and the case 19, an abnormal temperature rise in the brake fluid 5 can be detected. Thereafter, as the brake linings 1 and 1a wear out, the piston 4 moves to the left in FIG. 4 depending on the degree of wear, and when it reaches the wear limit position, it enters the state shown in FIG. 4. That is, the movable body 13 slides down from the side surface of the piston 4, the movable contact 17 and the fixed contact 22 are separated, and the fixed contact 22 and the case 19 become electrically open, so that the wear limit of the brake linings 1 and 1a is reduced. can be detected.

Effects of the Invention As explained above, according to the temperature and wear sensor of the present invention, a single sensor has both functions of detecting brake fluid temperature and brake lining wear, and is not disposable but semi-permanent. It has the advantage of being usable in many ways.

It also has a disconnection detection function because it is electrically opened only when wear of the brake lining is detected.

Furthermore, the first spring inside the movable body absorbs dimensional variations in the axial direction of each component and ensures electrical connection.
Since the second spring applies pressing force to the movable body and provides electrical connection, the design has a small number of parts, is inexpensive, and has high reliability.

[Brief explanation of the drawing]

1 and 2 are configuration diagrams showing a conventional sensor for detecting the wear limit of a brake lining, FIG. 3 is a configuration diagram showing the mounting state of a brake temperature and wear degree sensor according to the present invention, and FIG. 4 FIG. 2 is a cross-sectional view showing the internal configuration of the sensor. 1, 1a... Brake lining, 3... Cylinder, 4... Piston, 5... Brake fluid, 11
...sensor, 12...thermal element, 13...movable body, 14...first spring, 17...movable contact, 1
8... Second spring, 19... Case, 22... Fixed contact.

Claims (1)

[Claims] 1 A metal case, a fixed contact fixed in the case insulated from the case, and a bottomed cylindrical movable part whose bottom side is slidably pulled out from inside the case. a movable contact pulled out in an insulated state from an opening of the movable body toward the fixed contact; a heat-sensitive element provided with the other electrode in contact with the inner bottom surface of the movable body; a first spring interposed between one electrode and the movable contact and electrically connected between the two;
A second spring is provided that presses the movable body in a direction in which the movable contact and the fixed contact are separated and electrically connects the movable body and the case, and the outer bottom of the movable body is connected to the brake lining. A brake temperature and wear sensor is placed in contact with a connected piston in brake fluid.