CN201463833U

CN201463833U - Capacitance angle transducer

Info

Publication number: CN201463833U
Application number: CN2009201097102U
Authority: CN
Inventors: 肖跃华; 李建春; 谭映戈; 孙昕; 郑浩然; 才小士
Original assignee: China Aerospace Times Electronics Corp
Current assignee: China Aerospace Times Electronics Corp; Beijing Aerospace Control Instrument Institute
Priority date: 2009-07-03
Filing date: 2009-07-03
Publication date: 2010-05-12
Anticipated expiration: 2019-07-03

Abstract

The utility model discloses a capacitance angle transducer, comprising a front polar plate, a shaft, ceramic medium, a rear polar plate and a spacer, wherein the ceramic medium is fixed on the shaft; the front polar plate and the rear polar plate pass through the shaft to keep an interval between polar plates constant by the spacer and keep the same interval with the ceramic medium; the front polar plate and the rear polar plate are made of carbureted hydrogen ceramic material, and the front polar plate is provided with an exciting signal circuit; the exciting signal circuit uses an outer automatic gaining control circuit to provide an exciting power supply; and the rear polar plate is provided with a capacitance difference amplitude-modulation circuit. The utility model adopts the carbureted hydrogen ceramic polar plate material with low coefficient of inertia expansion and effectively reduces the inherent temperature drifting of the capacitance angle transducer; two polar plates are respectively provided with the exciting signal circuit and the capacitance difference amplitude-modulation circuit, thus simplifying the structure of the transducer; the exciting signal circuit produces an exciting signal with higher frequency to improve the sensitivity and the angle precision of the sensor; meanwhile, the outer automatic gaining control circuit is used for keeping sensor sensitivity stable at high temperature.

Description

A kind of capacitance type angle sensor

Technical field

The utility model relates to a kind of capacitance type angle sensor, particularly a kind of high sensitivity low temperature floats capacitance type angle sensor, can be used as the contactless finite angle angular measurement sensor under technical grade temperature (40 ℃～+ 85 ℃) environment, the angular transducer of swing motor.

Background technology

At present, the capacitance type angle sensor that adopts is divided into the change gap both at home and abroad, and variable area becomes medium etc., simultaneously also adopting the differential type structure, float phenomenon but all have temperature, because electric capacity itself, in hot conditions bottom crown distortion of materials, the change in pole plate gap, the change of useful area between pole plate, the temperature characterisitic that components and parts are intrinsic etc. all can bring temperature to float.Be used in Frame and sweep angular transducer on the motor, it is a servomechanism, diagonal position requires very strict, requirement is input control voltage and the strict proportion relation of position feedback in the technical grade temperature range, if the scanning accuracy that big temperature drift will directly influence motor appears in angular transducer.

The utility model content

Technology of the present utility model is dealt with problems and is: overcome the deficiencies in the prior art, a kind of capacitance type angle sensor is provided, this sensor construction is simple, temperature is floated low, highly sensitive.

Technical solution of the present utility model is: a kind of capacitance type angle sensor, comprise preceding pole plate, axle, ceramic dielectric, back pole plate, pad, ceramic dielectric is fixed on the axle, preceding pole plate and back pole plate pass axle and keep the gap between pole plate to fix by pad, and maintenance is identical with the gap of ceramic dielectric, pole plate is 1/4 fan-shaped pole plate before described, the shape of ceramic dielectric is identical with the shape of preceding pole plate, preceding pole plate and back pole plate adopt the hydrocarbon stupalith, before electric capacity difference modulation circuit is set on the pole plate output capacitance of angular transducer carried out differential conversion becomes magnitude of voltage, the excited signal circuit is set on the back pole plate provides excited signal for angular transducer, the excited signal circuit provides excitation power supply by outside automatic gain control circuit.

Pole plate, back pole plate are RO4350B type hydrocarbon stupalith before described.

The excited signal frequency that the excited signal circuit produces in the pole plate of described back is that 2Mhz, peak-to-peak value are 500V.

Described pad, axle adopt titanium alloy material.

The utility model beneficial effect compared with prior art is: the utility model is by adopting the hydrocarbon ceramic plates material of low linear expansion coefficient, effectively reduced the drift of capacitance type angle sensor intrinsic temperature, excited signal circuit and electric capacity difference modulation circuit are set respectively on two-plate, simplified the structure of sensor, the excited signal circuit produces the excited signal of higher frequency, the sensitivity and the angle precision of capacitance type angle sensor have been improved, utilize outside automatic gain control circuit simultaneously, make the sensitivity of capacitance type angle sensor constant substantially under high-temperature condition, make capacitance type angle sensor in the technical grade temperature range from before 50 jiaos of branches of drift be reduced to 2 jiaos of branches.

Description of drawings

Fig. 1 is a structural representation of the present utility model;

Fig. 2 is the planimetric map of pole plate before the utility model;

Fig. 3 is the planimetric map of pole plate behind the utility model;

Fig. 4 is the utility model electric capacity difference modulation circuit figure;

Fig. 5 is the utility model excited signal circuit diagram;

The automatic gain control circuit figure that Fig. 6 adopts for the utility model;

Fig. 7 is the high low temperature drift test of a utility model schematic diagram.

Embodiment

As shown in Figure 1, axle 2 is installed on the motor in advance, earlier preceding pole plate 1 shown in Figure 2 is attached on the base plate housing of motor by two pin location, then ceramic dielectric 3 is enclosed within on the axle 2, with four pads 5 gap between preceding pole plate 1 shown in Figure 2 and the back pole plate 4 shown in Figure 3 is fixed, and be screwed and tighten, the signal of external circuits control panel is connected sensor by the DB9 connector, constitute whole angle measuring system, with jackscrew that ceramic dielectric 3 is fixing with axle 2 at last, and the gap d 1 between assurance ceramic dielectric 3 and two-plate, d2 is the same.Preceding pole plate 1 wherein shown in Figure 2 be shaped as 1/4 fan-shaped pole plate, the shape of ceramic dielectric 3 is identical with shape, the size of preceding pole plate 1 shown in Figure 2, axle 2 drives ceramic dielectric 3 and rotates, the pole plate area of capacitance type angle sensor shown in Figure 1 is changed, promptly can take measurement of an angle thereby the output capacitance value is changed.This capacitance type angle sensor is the differential type plate condenser that two parallel metal sheets that insulating medium separates are formed, rotary ceramic medium 3 forms a medium between two fixed plates, its rotation causes the change of medium, electric capacity also changes thereupon, the voltage transformation that by the electric capacity difference modulation circuit 6 that is provided with on the preceding pole plate 1 its two-way electric capacity is held value again, and then adopt the difference amplification that ceramic dielectric 3 anglecs of rotation are converted to voltage, form an automatic gain control circuit by difference amplification two paths of signals and reference voltage and provide excitation power supply for the excited signal circuit 7 on the pole plate 4 of back.

At present, state's internal polar plate generally adopts the stupalith of low temperature linear expansion coefficient, perhaps quartz material, owing to also have excited signal circuit 7 on the back pole plate 4 of this sensor, preceding pole plate 1 is provided with electric capacity difference modulation circuit 6, so forward and backward plate material adopts the high frequency composite ceramic material of low-k, low linear expansion coefficient, the utility model mainly adopts RO4350B type hydrocarbon stupalith.

The utility model is provided with electric capacity difference modulation circuit 6 on preceding pole plate 1, as shown in Figure 4, circuit is made up of four diode D1, D2, D3, D4 and capacitor C 1, C2, differential capacitance S1 walks around into voltage signal V1 by just meeting diode D1 or D2 with the rectification circuit that C1 forms, differential capacitance S2 walks around into voltage signal V2 by just meeting diode D3 or D4 with the rectification circuit that C2 forms, and wherein capacitor C 1, C2 strobe.

The utility model is provided with excited signal circuit 7 on the pole plate 4 of back, as shown in Figure 5, circuit is made up of resistance R 10, R11, triode Q3, Q4 and a jar type core transformers JP2, this circuit can be exported excitatory oscillator signal by jar type core transformers JP2, this circuit adopts the self-excitation push-pull type to produce high frequency ac signal, change magnet excitation frequency by changing transformer JP2 magnetic core inductance, because capacitive reactance

Along with frequency raises, capacitive reactance reduces, output voltage increases, the raising of transducer sensitivity relies on the frequency of sensor excited signal, also just mean the sensitivity that improves sensor so improve magnet excitation frequency, high transformation ratio is amplified to several hectovolts with the AC signal peak-to-peak value, and such signal induces the same frequency AC signal of several volts of peak-to-peak value on two-way differential capacitance pole plate, and the excited signal frequency that the utility model excited signal circuit produces is that 2Mhz, peak-to-peak value are 500V.

The input voltage AGC of excited signal circuit 7 shown in Figure 5 is exported by agc circuit as shown in Figure 6, agc circuit is by variable resistor R1, resistance R 2, resistance R 3, resistance R 4, resistance R 5, variable resistor R6, resistance R 7, resistance R 8, resistance R 9, by diode D5, reverse ratio amplifying circuit that capacitor C 3 and operational amplifier LM324 form and triode Q1 form, two terminations ± 5 volt the voltage of variable resistor R1, one termination-5 volt the voltage of resistance R 7, the other end connects the volt input end of amplifier LM324, resistance R 2, resistance R 3, resistance R 4, resistance R 5, the positive pole of capacitor C 3 and diode D5, the collector of triode connects positive 15 volts of voltages, the positive input terminal ground connection of amplifier LM324. improving sensitivity of the present utility model is to reduce a kind of important means that temperature is floated, having had only electric capacity highly sensitive could responsive subtle change, adopt automatic gain control circuit (being AGC) that the sensitivity of sensor is proofreaied and correct. the principle of work of this circuit is: when environment temperature raises, because the expansion capacitance gap of plate material reduces, electric capacity increases, two-phase amplitude-modulated signal V1 in the accompanying drawing 4, V2 also increases, through corresponding VA and the VB that zooms in accompanying drawing 6 circuit of low-pass filtering, VA and VB and reference voltage are sued for peace, the error that obtains just reduces, error is carried out integration, integral result is connected to the base stage of triode Q1, triode amplifies this electric current and does excitation power supply for the electric capacity angular transducer by resistance R 9 output AGC voltages, excitation voltage diminishes, then signal VA and the VB after the two-way amplitude modulation also reduces, so agc circuit can guarantee that all the time the sensitivity of sensor is constant, guarantees that just VA and VB are constant.

Components and parts of the present utility model adopt low temperature to float components and parts, detector diode D1, D2, D3, D4, D5 all adopt the array diode, operational amplifier LM324 adopts the four high guaily unit of technical grade, and it is components and parts below 50ppm/ ℃ that all the other resistance, electric capacity all adopt temperature coefficient.

The utility model is carried out high low temperature drift test, test philosophy as shown in Figure 7, capacitance type angle sensor described in the utility model is installed in frame to be swept on the motor 72 and with circuit control panel and puts into high-low temperature chamber 71, frame is swept motor 72 to power on, get on the motor load eyeglass 75 through the glass 74 of high-low temperature chamber with the laser beam that laser instrument 73 sends, and reflex on the coordinate paper 76 on opposite.After normal temperature energising 5 minutes, with the precision DC current regulator regulate given magnitude of voltage U1 (given in this test ± 5V, ± 7V, ± 9V), on coordinate paper 76, make the corresponding groove mark of these 6 magnitudes of voltage respectively, mark finishes and shuts down.First then high temperature+60 ℃, the insulation 1h after again with the precision DC current regulator regulate given magnitude of voltage U1 (given in this test ± 5V, ± 7V, ± 9V), note respective output voltages U2 ' (pin 3 in the table 1).Observe light spot position, on coordinate paper 76, make a mark, the intact shutdown of mark, there is a variation position of the position of this tense marker and normal temperature tense marker, the radian value that after measuring this difference on the coordinate paper, obtains drifting about divided by this distance of putting mirror of correspondence, be converted into angle value again and be designated as a (a has sign, and unit is the angle branch), a is exactly the angle drift value of temperature for+60 ℃ of corresponding input voltages.Bring formula into | U2-U2 ' | * 120 '-a, calculate drift positional precision (U2 is the output voltage of corresponding identical U1 under the normal temperature).Under the soak situation, voltage by agc circuit output is reducing always, the capacitance type angle sensor sensitivity that influences owing to high temperature has just changed, drift has appearred, agc circuit is proofreaied and correct in the sensitivity to sensor always, and the luminous point 50 jiaos of branches that drifted about in the past drift in 2 jiaos of branches now, temperature is floated the result and is reduced greatly, has realized that just low temperature floats capacitance type angle sensor.

The undeclared content of the utility model is a technology as well known to those skilled in the art.

Claims

1. capacitance type angle sensor, it is characterized in that: comprise preceding pole plate (1), axle (2), ceramic dielectric (3), back pole plate (4), pad (5), ceramic dielectric (3) is fixed on the axle (2), preceding pole plate (1) and back pole plate (4) pass axle (2) and keep the gap between pole plate to fix by pad (5), and maintenance is identical with the gap of ceramic dielectric (3), pole plate (1) is 1/4 fan-shaped pole plate before described, the shape of ceramic dielectric (3) is identical with the shape of preceding pole plate (1), preceding pole plate (1) and back pole plate (4) adopt the hydrocarbon stupalith, before electric capacity difference modulation circuit (6) is set on the pole plate (1) output capacitance of angular transducer carried out differential conversion becomes magnitude of voltage, excited signal circuit (7) is set for angular transducer provides excited signal on the back pole plate (4), excited signal circuit (7) provides excitation power supply by outside automatic gain control circuit.

2. a kind of capacitance type angle sensor according to claim 1 is characterized in that: pole plate (1), back pole plate (4) are RO4350B type hydrocarbon stupalith before described.

3. a kind of capacitance type angle sensor according to claim 1 is characterized in that: the excited signal frequency that excited signal circuit (7) produces in the described back pole plate (4) is that 2Mhz, peak-to-peak value are 500V.

4. a kind of capacitance type angle sensor according to claim 1 is characterized in that: described pad (5), axle (2) adopt titanium alloy material.