CN201069353Y - A braking friction sheet thickness sensor for resistance car - Google Patents

Abstract

The utility model relates to a resistance-type automotive brake lining thickness sensor which is used to measure the thickness of an automotive brake lining. The utility model comprises a precision resistor (1) and a driver circuit. The precision resistor (1) is embedded in a brake lining (4) and is worn along with the brake lining (4) during the braking process of a car, resulting in the change in resistance. The precision resistor (1) is also connected with the driver circuit. The driver circuit is an oscillating circuit consisting of an operational amplifier (5), a first resistor (6), a second resistor (7), a capacitance (8) and the connected wired precision resistor (1); and outputs rectangular wave signals with a certain amplitude value. The frequency of the rectangular wave signal changes along with the resistance of the precision resistor (1), so that the change in thickness of the brake lining is represented by the change in measurable frequency signal. The sensor has the advantages of simple structure, stable output and strict linear relationship between output and input, and is used for the continuous detection of brake lining thickness.

Description

A kind of resistance-type Thickness of Motor Vehicle's Braking Friction Plate sensor

Technical field

The utility model is a kind of resistance-type Thickness of Motor Vehicle's Braking Friction Plate sensor, is used for the measurement of Thickness of Motor Vehicle's Braking Friction Plate, belongs to brake system of car robotization detection range.

Background technology

Friction disc is the critical component in the brake system of car, friction disc is very easy to wearing and tearing and makes its thickness attenuation in the Motor Vehicle Braking Procedure under high temperature and strong friction, will cause brake failure and have an accident if the thickness of friction disc surpasses maximum safe limit, thus detect the thickness of friction disc make its remain on maximum safe limit with interior be the important assurance of the stable and vehicle safety travel of brake system of car.

At present, the method for detection friction disc thickness mainly contains two classes.One class is a direct method, it is to rely on driver's experiences regularly to take the thickness that detent is observed friction disc apart, this method not only lose time and also reliability not high, sometimes because of the one-tenth-value thickness 1/10 of in time not checking friction disc make friction disc wear cause brake failure to cause traffic hazard to maximum safe limit.Another kind of is indirect method, this method mainly be utilize the mechanical hook-up be installed in the friction disc and peripheral servicing unit as: circuit, alarm wait the detection that realizes friction disc thickness.Though convenience and fiduciary level that this method detects increase than first method, but because having only when friction disc thickness could move both peripheral circuit connections during to maximum safe limit, the mechanical hook-up that is installed together with friction disc sends alerting signal, so can not realize the early warning of friction disc thickness maximum safe limit and the one-tenth-value thickness 1/10 continuous detecting of friction disc.

The utility model content

The purpose of this utility model has been to overcome the deficiency that traditional friction disc thickness detecting method can only detect thickness maximum safe limit value, a kind of sensor that can realize friction disc thickness continuous detecting simple in structure, easy for installation is provided, and this sensor can directly apply to the friction disc thickness detecting system.

To achieve these goals, the utility model has been taked following technical scheme.Mainly include precision resistance 1, driving circuit 2, wherein, precision resistance 1 is embedded in brake strip 4 inside, and 1 height h is identical with the thickness of brake strip 4 for precision resistance; Precision resistance 1 is for the uniform cross section column and two equidistant electrodes 2 are arranged, and electrode 2 runs through the whole height of precision resistance 1, and precision resistance 1 inserts driving circuit by electrode 2.

Described driving circuit includes operational amplifier 5, first resistance 6, second resistance 7, electric capacity 8, wherein, the in-phase input end and the output terminal of first resistance, 6 concatenation operation amplifiers, the in-phase input end of second resistance, 7 one termination operational amplifiers, other end ground connection, the inverting input of electric capacity 8 one termination operational amplifiers 5, other end ground connection is embedded in precision resistance 1 in the friction disc is connected on operational amplifier 5 by input wires terminal 9 inverting input and output terminal.

Principle of work of the present utility model is as follows: the height of precision resistance is made as h, the distance of two equidistant electrodes 2 is made as L, be made as d with the width on the two electrode connecting line vertical direction, resistivity is made as ρ, by physical knowledge as can be known the resistance R of precision resistance 1 satisfy following relation:

$R=\mathrm{\ρ}\frac{L}{\mathrm{dh}}---\left(1\right)$

So when wearing and tearing take place in friction disc 4, friction disc 4 thickness change, precision resistance 1 and the friction disc height h that causes precision resistance 1 that weares and teares simultaneously changes, by formula (1) as can be known, the resistance of precision resistance 1 also changes, and so just the change transitions of friction disc thickness is become the variation of precision resistance 1 resistance.

Then precision resistance 1 is inserted driving circuit, driving circuit is mainly by operational amplifier 5, first resistance 6, second resistance 7, electric capacity 8, input wires terminal 9 and signal output wiring terminal 10 are formed, operational amplifier 5, first resistance 6, second resistance 7, electric capacity 8 and constitute oscillatory circuit in the driving circuit by the precision resistance 1 in the friction disc of being embedded in that input wires terminal 9 inserts, oscillatory circuit is output as rectangular waveform signal when work, the amplitude of square-wave signal is by operational amplifier 5 added voltage decisions, its frequency is by first resistance 6, second resistance 7, the resistance of the precision resistance 1 that inserts and the decision of the capacitance of electric capacity 8, if the resistance of first resistance 6 is R1, the resistance of second resistance 7 is R2, the electric capacity of electric capacity 8 is C, the resistance of precision resistance 1 is R, and the frequency f of oscillatory circuit satisfies following relation:

$f=\frac{1}{2\mathrm{RC}\ln (1+\frac{2R1}{R2})}---\left(2\right)$

After the resistance of first resistance 6, second resistance 7 and electric capacity 8 capacitances are determined as can be known by formula (2), the frequency f of oscillatory circuit changes with the variation of the precision resistance that is embedded in friction disc 1 resistance of outer access, so oscillatory circuit can become the change transitions of precision resistance 1 resistance the variation of oscillatory circuit frequency.

Again formula (1) substitution formula (2) can be got following relation:

$f=\frac{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="Y20072017013300071.png,Y20072017013300081.png"\; state="\{\{state\}\}">d</figure-callout>}}{2\mathrm{\&rho;}\mathrm{LC}\ln (1+\frac{2R1}{R2})}h---\left(3\right)$

Precision resistance 1 weares and teares simultaneously with it when wearing and tearing take place friction disc 4, the height h of precision resistance 1 changes, the distance L of two electrodes, all do not change the resistance R1 of first resistance 6 in the oscillatory circuit, the resistance R2 of second resistance 7 with the width d of two electrode vertical direction and the electricalresistivity of precision resistance, the capacitance C of electric capacity 8 is a definite value, so last in (3) formula is definite value, is made as k, can get following formula:

f＝kh (4)

Frequency f and the height h of precision resistance of oscillatory circuit are that the thickness of friction disc is directly proportional as can be known by (4) formula, so the variation in thickness of friction disc 4 can be transformed into the frequency change of oscillatory circuit by precision resistance 1 and oscillatory circuit, and satisfy exact linear relationship, so just realized the continuous detecting of friction disc thickness.

The utility model has the advantages that: highly the precision resistance identical with friction disc thickness is embedded in precision resistance and friction disc worn and torn simultaneously, realized the continuous acquisition of friction disc thickness signal; The core that with the oscillatory circuit is driving circuit becomes the variation of square wave frequency with the change transitions of precision resistance resistance, and it is simple in structure, output is stable and strict linear relationship is satisfied in input, output.

Description of drawings

The utility model is described in further detail below in conjunction with accompanying drawing and exemplifying embodiment.

Fig. 1 precision resistance structural front view;

Fig. 2 precision resistance structure vertical view;

The scheme of installation of Fig. 3 precision resistance and friction disc;

Fig. 4 driving circuit synoptic diagram;

Fig. 5 overall construction drawing of the present utility model;

Among the figure: 1, precision resistance, 2, electrode, 3, plastic casing, 4, brake strip, 5, operational amplifier, 6, first resistance, 7, second resistance, 8, electric capacity, 9, the input wires terminal, 10, output wiring terminal.

Embodiment

Embodiment of the present utility model is as follows: with reference to Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, the precision resistance 1 that is embedded in the friction disc adopts metalfilmresistor, resistance is 1K, error range 0.01%～0.1%, be processed into the uniform cross section column, its height is identical with the thickness of friction disc, electrode 2 in the precision resistance 1 is equidistantly and runs through the whole height of resistance, precision resistance 1 is installed in the plastic casing 3, plastic casing 3 is installed in 4 li of brake strips, between plastic casing 3 and the friction disc 4 for being threaded, by electrode 2 precision resistance 1 is connected input wires terminal 9 in the driving circuit, the in-phase input end and the output terminal of first resistance, 6 concatenation operation amplifiers in the driving circuit, the in-phase input end of second resistance, 7 one termination operational amplifiers, other end ground connection, the inverting input of electric capacity 8 one termination operational amplifiers 5, other end ground connection, be embedded in precision resistance 1 in the friction disc and be connected on the inverting input and the output terminal of operational amplifier 5 by input wires terminal 9, the drive circuitry power supply is ± the 12V direct supply that driving circuit is by lead-out terminal 10 outputs.

Driving circuit access ± 12V power supply, sensor is started working, the output end of oscillating circuit that is made of the precision resistance 1, operational amplifier 5, first resistance 6, second resistance 7, the electric capacity 8 that are embedded in the friction disc is ± the 12V square-wave signal, when the friction disc variation in thickness, precision resistance 1 resistance that is embedded in wherein also can change thereupon, and then the frequency of rectangular wave of driving circuit output also changes, and the change transitions of the one-tenth-value thickness 1/10 of friction disc one-tenth is convenient to the variation of survey frequency signal like this.

Claims (2)

1. resistance-type Thickness of Motor Vehicle's Braking Friction Plate sensor, it is characterized in that: mainly include precision resistance (1), driving circuit (2), wherein, precision resistance (1) is embedded in brake strip (4) inside, and h is identical with the thickness of brake strip (4) for precision resistance (1) height; Precision resistance (1) is for the uniform cross section column and two equidistant electrodes (2) are arranged, and electrode (2) runs through the whole height of precision resistance (1), and precision resistance (1) inserts driving circuit by electrode (2).

2. a kind of resistance-type Thickness of Motor Vehicle's Braking Friction Plate sensor according to claim 1, it is characterized in that: described driving circuit includes operational amplifier (5), first resistance (6), second resistance (7), electric capacity (8), wherein, the in-phase input end and the output terminal of first resistance (6) concatenation operation amplifier, the in-phase input end of second resistance (7) one termination operational amplifiers, other end ground connection, the inverting input of electric capacity (8) one termination operational amplifiers (5), other end ground connection is embedded in precision resistance (1) in the friction disc is connected on operational amplifier (5) by input wires terminal (9) inverting input and output terminal.

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