JP2018017281A - Non-power supply wear sensor and wear sensor system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a wearing degree or an intermittent elapsing of wearing to be judged and at the same time eliminate a power supply at a disc brake, for example, and also eliminate assuring of a battery cell arrangement space as well as wiring and the routing wire.SOLUTION: A non-power supply wearing sensor 1 comprises a pair of conductive patterns 6 worn out in response to wearing of a brake pad 13 so as to detect a wearing amount of the brake pad 13 in reference to a variation of capacitance corresponding to this wearing; and SAW device 5 having comb-like electrode pairs 3 and comb-like electrode pairs 4 having a delay time of 1 μs in respect to the comb-like electrode pairs 3 formed at a piezoelectric substrate. An antenna 2 is connected to one of the comb-like electrode pairs 3 and a conductive pattern 6 is connected to the other comb-like electrode pairs 4, a burst wave is inputted to the non-power supply wearing sensor 1 from a transmittance/receiving measuring part 9 and a wearing degree of the brake pad 13 is measured in reference to a variation of amplitude of its reflection burst wave.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-power supply wear sensor and a wear sensor system that can detect wear of a brake pad or the like using a SAW device and can be arranged without a power supply.

Conventionally, for example, a brake pad is used in a disc brake for braking a vehicle, and the wear is detected in this brake pad. As a detection method, there are methods shown in FIGS. 4 (A) and 4 (B). .
FIG. 4A shows an electric detection method. As shown in FIG. 4A, the disc brake is configured such that the brake pad 13 supported by the back plate 12 is pressed against the disc rotor 14. A wire 15 is embedded in the brake pad 13. According to this, when the brake pad 13 is worn down to a predetermined position by friction, the wire 15 is disconnected, and the wear state of the brake pad 13 is detected.

  FIG. 4B shows an audible detection method (Patent Document 1 below). As shown in FIG. 4B, in a disc brake, a piece of metal such as stainless steel is provided at a predetermined thickness position of the brake pad 13. 16 is arranged. According to this, when the brake pad 13 is worn down to a predetermined position, the disc rotor 14 comes into contact with the metal piece 16 and generates a chatter sound, whereby the wear state of the brake pad 13 is detected.

JP 2010-151221 A JP 2006-516701 A

  However, in the conventional wear sensor described above, the brake pad 13 is worn to a predetermined position or more because the wear is detected by a break of the wire 15 arranged at a predetermined thickness position or a chatter sound caused by the metal piece 16. However, the degree of wear and the progress of wear could not be judged.

Further, in the electric detection method shown in FIG. 4A, a power source for energizing the wire 15 is necessary, and for example, when a battery is used as the power source, a space for arranging the battery must be secured. When using the power source of the vehicle, there is an inconvenience that wiring to the disc brake and its routing are complicated.
Furthermore, as shown in the above-mentioned Patent Document 2, there is a type in which a parallel plate capacitor is disposed on a brake pad and wear is detected by a change in the capacitance of the parallel plate capacitor. There is.

  The present invention has been made in view of the above-mentioned problems, and its object is to determine the degree of wear and the progress of wear, and for example, in a disc brake, it is not necessary to have a power source, and the battery arrangement space It is an object of the present invention to provide a non-power-source wear sensor and wear sensor system that eliminates the need for securing the wiring, wiring to the disc brake, and routing.

  In order to achieve the above object, the non-power supply wear sensor of the invention according to claim 1 is mounted so as to be worn according to the wear on the object to be measured, and the object to be measured is caused by a change in capacity according to the wear. A pair of conductive patterns for detecting the amount of wear, an antenna, one comb electrode pair, and another comb electrode pair having a predetermined delay time with respect to the one comb electrode pair are formed on the piezoelectric substrate. A surface acoustic wave device in which the antenna is connected to the one comb electrode pair and the conductive pattern is connected to the other comb electrode pair, and the one comb electrode pair is input from the antenna. The transmitted electric signal is converted into a surface acoustic wave and transmitted, and the other comb electrode pair is transmitted from the one comb electrode pair with the reflectance changed according to the wear amount of the pair of conductive patterns. One of the above, reflecting surface acoustic waves Comb-shaped electrode pairs is converted into an electric signal by receiving the surface acoustic wave reflected by the other of the comb electrode pair, and output to the antenna, and outputs the reflected signal from the antenna.

A wear sensor system according to a second aspect of the invention transmits the wear detection signal to the non-power wear sensor and the non-power wear sensor, receives the reflection signal, and determines the amplitude or phase of the received reflection signal. And a transmission / reception / measurement unit for measuring wear of an object to be measured due to fluctuations.
The transmission / reception / measurement unit of the wear sensor system according to claim 3 transmits a burst wave as a wear detection signal.
The transmission / reception / measurement unit of the wear sensor system according to claim 4 transmits an FMCW wave obtained by frequency-modulating a continuous wave as a wear detection signal.

  According to the above configuration, as the pair of conductive patterns, for example, a substrate in which two conductive wires or flat plates are arranged in parallel (printed circuit board or the like) is used. It arrange | positions so that it may wear with (measuring object), and the capacity | capacitance between conductive patterns will change because a pair of conductive pattern also wears according to wear of a brake pad. The change in capacitance is detected by a reflected wave from the surface acoustic wave element when the conductive pattern is connected to the surface acoustic wave element.

  That is, for example, when a burst wave of a predetermined frequency is transmitted from the transmission / reception / measurement unit to the non-power supply wear sensor, a reflected burst wave having a predetermined delay time is reflected from the surface acoustic wave element. The wear of the brake pad is measured by detecting the fluctuation of the amplitude (or phase) of the received reflected wave.

  According to the non-power supply wear sensor and wear sensor system of the present invention, the degree of wear and the progress of wear are obtained by utilizing the characteristic that the reflected wave level of the surface acoustic wave element changes depending on the capacitance between a pair of conductive patterns. This eliminates the need to place a power supply around the disc brake that is the object to be measured and its surroundings, which eliminates the need for battery space, wiring and routing to the disc brake, and the effect of realizing wireless. is there.

It is a figure which shows the structure of the non-power-source wear sensor and wear sensor system which concern on the Example of this invention. It is explanatory drawing which shows the signal for wear detection transmitted / received in an Example. It is a perspective view which shows the specific structure of the non-power supply wear sensor of an Example (the non-power supply wear sensor was expanded). The structure of the conventional wear sensor is shown, FIG. (A) is an electrical explanatory diagram, and (B) is an audible explanatory diagram.

  1 to 3 show the configuration of a non-power wear sensor and wear sensor system of the embodiment. In FIG. 1, 1 is a non-power wear sensor, 2 is an antenna, and 3 is one connected to an antenna 2. The comb-shaped electrode pair 4 has a predetermined delay time (for example, 1 μs) with respect to the one comb-shaped electrode pair 3, and the other comb-shaped electrode pair 5 has surface elasticity in which the comb-shaped electrode pairs 3 and 4 are formed on the piezoelectric substrate. A wave element (SAW device) 6 is connected to the comb-shaped electrode pair 4 and is a pair of conductive patterns for setting capacitance (electrical characteristics).

  As shown in FIG. 3, the pair of conductive patterns 6 of the example is a conductive substrate in which two conductive wires (metal foil) having a predetermined width are arranged and formed in parallel on a dielectric substrate (similar to a printed circuit board). By attaching the non-power supply wear sensor 1 to the insertion hole of the brake pad 13 from the back plate 12 side of the disc brake, the two conductive wires of the conductive pattern 6 are connected in the thickness direction of the brake pad 13. Are arranged so that the extending direction of the conductive pattern coincides with the thickness direction. In this way, the two conductive wires are worn with the wear of the brake pad 13 from the front end side. The pair of conductive patterns 6 may be formed by arranging two strip-like planar metal foils that are long in the thickness direction of the brake pad 13 in parallel with the upper and lower sides of the substrate.

As shown in FIG. 1, a transmission / reception / measurement unit 9 having an antenna 8 is provided as a component of the wear sensor system.
FIG. 2 shows a wear detection signal input / output to / from the non-power supply wear sensor 1 (transmitted / received by the transmission / reception / measurement unit 9). In the embodiment, for example, a burst wave of 920 MHz having a width of 1 μs is shown. (Pulse wave) is sequentially transmitted at intervals of 5 μs. Further, the other comb electrode pair 4 of the SAW device 5 is set so as to have a delay time of 1 μs from the one comb electrode pair 3. Therefore, as shown in FIG. 2, the SAW device 5 has a 920 MHz burst. The 920 MHz reflected burst wave Sr is output with a delay of 2 μs with respect to the input of the wave Sa.

  The embodiment has the above-described configuration, and the wear detection signal is transmitted from the transmission / reception / measurement unit 9, and the no-power wear sensor 1 receives the burst wave Sa burst wave of 920 MHz every 5 μs via the antenna 2. . Then, in the SAW device 5, the reflected burst wave Sr delayed by 2 μs, which is twice the delay time 1 μs, appears every 5 μs.

  That is, the burst wave Sa input to the SAW device 5 is converted into a surface acoustic wave by one comb electrode pair 3 formed on the piezoelectric substrate and reaches the other comb electrode pair 4. In the other comb-shaped electrode pair 4, the conductive pattern 6 of the two conductive line prints is connected, and there is a distributed constant capacitance value C according to the length between the two conductive lines. The surface acoustic wave having an amplitude (level) based on the capacitance value C is reflected. Here, since the two conductive lines of the conductive pattern 6 are shortened with wear of the brake pad 13 and the capacitance value C becomes small, the amplitude of the surface acoustic wave fluctuates (for example, increases) due to the change in the capacitance value C. ). The surface acoustic wave reflected by the other comb electrode pair 4 is received by the one comb electrode pair 3, converted into a reflected burst wave Sr, and output from the antenna 2.

  The reflected burst wave Sr output from the non-power supply wear sensor 1 (SAW device 5) is received by the transmission / reception / measurement unit 9, and the degree of wear of the brake pad 13 is measured by the fluctuation of the amplitude of the reflected burst wave Sr. . The two conductive wires of the conductive pattern 6 are worn from the tip in accordance with wear of the brake pad 13 and become shorter (the capacity between the conductive wires is also small), so how much the brake pad 13 is worn. Thus, it is possible to predict the replacement timing of the brake pad 13.

  As described above, since the wear detection signal is a burst wave in the embodiment, the time axis can be separated, and the reflected burst wave can be easily extracted. In addition, by separating the function of the antenna 8 of the transmission / reception / measurement unit 9 from reception and transmission, even if the wear detection signal is an FMCW wave obtained by frequency-modulating a continuous wave, the frequency difference between the transmission signal and the reception signal (beat ) Allows separation of reflected waves.

  In the above embodiment, a change in capacitance (change in electrical characteristics) is detected by a change in the amplitude of the reflected burst wave Sr. However, sensing can also be performed by capturing the phase of the reflected burst wave Sr. That is, since the change in the capacitance of the conductive pattern 6 changes the phase of the reflected burst wave Sr having a predetermined frequency, the wear of the object to be measured is measured by detecting the change in the phase according to the change in the capacitance value. be able to.

  In the above-described embodiment, the case where the object to be measured is the brake pad 13 has been described. However, the present invention can be applied with another object to be worn as the object to be measured.

1 ... Non-power wear sensor, 2,8 ... Antenna,
3 ... one comb electrode pair, 4 ... the other comb electrode pair,
5 ... SAW device (surface acoustic wave device),
6 ... conductive pattern, 9 ... transmission / reception / measurement unit,
12 ... Back plate, 13 ... Brake pad,
Sa: burst wave, Sr: reflected burst wave.

Claims (4)

A pair of conductive patterns that are attached to the object to be measured so as to wear according to the wear, and for detecting the amount of wear of the object to be measured by a change in capacity according to the wear,
An antenna,
One comb electrode pair and the other comb electrode pair having a predetermined delay time with respect to the one comb electrode pair are formed on the piezoelectric substrate, the antenna is connected to the one comb electrode pair, and the other comb A surface acoustic wave element formed by connecting the conductive pattern to a mold electrode pair,
The one comb-shaped electrode pair converts the electric signal input from the antenna into a surface acoustic wave and transmits it,
The other comb electrode pair reflects the surface acoustic wave transmitted from the one comb electrode pair by changing the reflectivity according to the wear amount of the pair of conductive patterns,
The one comb electrode pair receives the surface acoustic wave reflected by the other comb electrode pair, converts it into an electrical signal, and outputs it to the antenna.
A non-power supply wear sensor that outputs a reflected signal from the antenna. A pair of conductive patterns that are mounted on the object to be measured according to its wear, and for detecting the amount of wear of the object to be measured by a change in capacity according to the wear,
An antenna, and one comb electrode pair and the other comb electrode pair having a predetermined delay time with respect to the one comb electrode pair are formed on a piezoelectric substrate, the antenna is connected to the one comb electrode pair, and Including a surface acoustic wave element formed by connecting the conductive pattern to the other comb-shaped electrode pair,
The one comb electrode pair converts the electric signal input from the antenna into a surface acoustic wave and transmits it, and the other comb electrode pair changes the reflectance according to the wear amount of the pair of conductive patterns. The surface acoustic wave transmitted from the one comb electrode pair is reflected, the surface acoustic wave reflected by the other comb electrode pair is received by the one comb electrode pair, and converted into an electrical signal, A non-power wear sensor that outputs to the antenna and outputs a reflected signal from the antenna;
A transmission / reception / measurement unit that transmits a wear detection signal to the non-power supply wear sensor, receives the reflection signal, and measures wear of the object to be measured based on fluctuations in the amplitude or phase of the received reflection signal. Wear sensor system.   The wear sensor system according to claim 2, wherein the transmission / reception / measurement unit transmits a burst wave as a wear detection signal.   The wear sensor system according to claim 2, wherein the transmission / reception / measurement unit transmits an FMCW wave obtained by frequency-modulating a continuous wave as a wear detection signal.

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