CN2684153Y - Three-parameter integration capacitance sensor for automobile fuel meter - Google Patents

Abstract

The utility model relates to a three-parameter integration capacitance sensor for an automobile fuel meter, which is chiefly used for metering exactly fuel volumes of automobiles and outputting simultaneously the measuring signal voltage in direct proportion to the permittivity of oil devices with the three parameters of oil permittivity epsilon, fuel head h and container cross section S (h). The utility model comprises a sensing capacitance component and a circuit component which are connected by conducting wires. The sensing component is composed of a metal outer tube, an upper and a lower two-section inner tubes, an insulating ring and a fixed disc which form two measuring capacitors C <L> and C <epsilon>. The circuit component has a stabilized power supply circuit, two groups of pulse width modulation type C / U conversion circuits and two groups of operational amplification circuits, and the sensor outputs simultaneously two groups of signal voltage. The utility model has novel and unique structure, scientific and rational design, superior technical performance and extensive application prospect.

Description

The vehicle fuel meter is with three parameter integral capacitive transducers

Technical field

A kind of vehicle fuel meter that the utility model relates to the measuring apparatus field is with three parameter integral capacitive transducers.

Background technology

Generally adopt in existing vehicle fuel meter field is float-type power transformation resistance sensor, can't definitely measure the true capacity of fuel tank of vehicle intermediate fuel oil, the relative reference amount of its indication exists＞and the error of 5%-10%.Lag behind the overall development level of automotive engineering, can not adapt to automobilism the fuel oil requirement of concluding the business.In Chinese patent 02201906.5, announced a kind of " two-dimensional integration function capacitive transducer ", though realized the high precision that automobile oil mass is measured, but change owing to the dielectric capacitance rate when in use changing oil brand thereupon, circuit parameter is readjusted in requirement, thereby certain limitation is also arranged, need the further raising of designing technique and perfect.

The utility model content

The purpose of this utility model provides a kind of vehicle fuel meter with three parameter integral capacitive transducers, realizes relating to the oil product permittivity, fuel head, the signal transformation and the measurement of three physical parameters of fuel tank sectional area in the vehicle fuel metering.It solves by following technical proposals.Design a kind of sensing capacitance parts and circuit block, the design feature of sensing capacitance parts is metal outer pipe, interior pipe A, interior pipe B, dead ring, and fixedly the garden dish goes between, and forms two different purposes sensing capacitance of integrated combination again.The electric capacity that pipe A and outer tube are formed wherein is two parameter integral sensing capacitance C _L, be used to measure the integration of fuel container sectional area to liquid level.The capacitor C that interior pipe B and outer tube are formed _εBe oil product permittivity sensing capacitance, be used to measure the permittivity of medium oil product.The instant data of required the 3rd parameter are provided for the two-dimensional integration capacitive transducer.The interior pipe A of sensing capacitor, interior pipe B, outer tube are isolated with dead ring each other, and secure fit, and the outer tube top fixedly secures in fixing garden and coils endoporus.The sensing capacitor overall height is consistent with the height of tested container.Sensing capacitor vertically is installed in the geometric center of nearly container during use by fixing garden dish.

The sensing capacitance parts are a kind of assembled tube type capacity cells, by pipe, inner and outer pipe lead-in wire in dead ring, metal outer pipe, the two-section, fixedly garden dish, radome are formed, metal outer pipe respectively with interior pipe A, interior pipe B formation oil mass sensing capacitor C _LWith oil product permittivity sensing capacitor C _ε, be provided with dead ring between the tube and tube, oil mass sensing capacitor C _LDistribution function 1 (h) dh of active electrode area of interior pipe A and sectional area distribution function S (h) linear dependence of tested container, wherein 1 (h) is that the tube wall of interior pipe A is at the distribution function of effective garden of a certain liquid level arc length degree to this liquid level, its implementation is in the corresponding window formula hole of processing on the tube wall and fills typing insulating material, oil product permittivity sensing capacitor C between inner and outer pipes _εInterior pipe B place in the pipe A the lower end, its significant height is no more than the height of vehicle fuel warning pasta, fixedly the garden dish is located at the upper end of sensing capacitance element, fixedly be provided with radome on the dish of garden, total significant height of sensing capacitance element equates with the significant height of tested container, the lower end is provided with oil supply hole, and the upper end is provided with air hole;

Circuit block constitutes voltage-stabilized power supply circuit respectively by adjustable positive output shunt regulator, hex inverter, single supply dual operational amplifier and resistance, di-cap, the C/U translation circuit, subtraction and scale operation circuit, wherein: voltage-stabilized power supply circuit is by dropping resistor, electric resistance partial pressure signal circuit and adjustable positive output shunt regulator constitute, and press for the sensor internal circuit provides galvanic current.

Two group pulse width modulation type C/U translation circuits are made up of hex inverter and resistance, electric capacity, diode respectively, after connecting stabilized voltage supply, the impulse hunting of two groups of circuit and shaping unit produce the wide rect.p. of constant amplitude that dutycycle equals 1 respectively, and the pulsed modulation part of two groups of circuit is respectively according to C _L, C _εThe size modulations pulse width, make its dutycycle be not equal to 1, and respectively with C _L, C _εBig or small corresponding, electric pulse paraphase, filtering after the paraphase of two groups of circuit, rectification partly will be modulated respectively obtain corresponding direct-flow signal voltage U _L, U _εThereby, realize C respectively _L/ U _L, C _ε/ U _εConversion;

Two groups of operational amplification circuits are made up of single supply dual operational amplifier and resistance, electric capacity, potentiometer, respectively at input U _L, U _εBehind the direct-flow signal voltage, carry out U _L-U _L0, U _ε-U _{ε 0}Computing and ratio are amplified, U _L0And U _{ε 0}The bleeder circuit of being made up of resistance, potentiometer is adjusted to set-point according to design parameter respectively, this circuit output V _L, V _εTwo groups of signal voltages, V _LWith the be integrated into direct ratio of tested fuel tank sectional area to liquid level, V _εBe directly proportional with the oil product permittivity and the measuring voltage corresponding with capacity international unit in the given fuel tank is directly proportional.The two is in the analog to digital conversion circuit of oil mass read out instrument, as aanalogvoltage and reference voltage;

Temperature-compensation circuit adopts thermistor, is used for the change that compensation temperature changes the circuit parameter that causes;

Circuit component designs on a printed on both sides wiring board, and is fixed in the top radome of sensing capacitance element.Insert direct supply by lead, export two groups of measurement signal voltages.

Hex inverter is 4069 in the foregoing circuit, and dual operational amplifier is 2904, and shunt regulator is 431.

The relative prior art of the utility model has following characteristics.

1, the existing relatively vehicle fuel meter that generally uses except that having improved measuring accuracy, has realized that also movement-less part does not have measurement friction force, reliability height, long service life, coincidence measurement principle more with float-type power transformation resistance sensor.

2, relatively the utility model people design and the two-dimensional integration function capacitive transducer of obtaining utility model patent have increased measurement parameter ε _x, when being applied to different oil products and measuring, provide ε for two-dimensional integration function capacitive transducer _xInstant data, solved use in general, interchange issues, thereby more convenient and practical.

3, realized the linear transfer function relation, and when the output signal number was changed, the numeric results of measurement and the permittivity of oil product had nothing to do.

Description of drawings

Fig. 1 is the utility model sensing capacitance parts example structure synoptic diagram.

Fig. 2 is the utility model embodiment circuit theory diagrams.

Below in conjunction with accompanying drawing the utility model embodiment is further described.

Shown in the accompanying drawing 1, measure and use capacity cell C ₂Form by metal outer pipe 2 and interior pipe A, measure and use capacity cell C _εForm by metal outer pipe 2 and interior pipe B, metal outer pipe 2, interior pipe A, interior pipe B isolate with dead ring 1a, 1b, 1c, 1d mutually, and firmly make up on an axis, the upper end of metal outer pipe 2 is fastened on the fixed disc 8, outer tube 2, interior pipe B, interior pipe A crimping extension line 4,5,6 respectively are connected in the circuit block, and lead-in wire 5 is a shielded conductor.Circuit block 7 integral installations are on the sensing capacitor top, and with crown cap 3 shielding protections.Fill two kinds of composite means of typing insulating material with machinery or chemical method in interior pipe A tube wall conductor uplifting window formula hole with at interior pipe A and outer tube 2 ring plate gaps, the distribution function and the tested container horizontal sectional area function linear dependence of the effective arc length of pipe A tube wall in realizing, promptly $1\left(h\right)=\frac{s\left(h\right)}{k};$

As shown in Figure 2, circuit block comprises voltage-stabilized power supply circuit, C _L/ U _LTranslation circuit, C _ε/ U _εTranslation circuit and operational amplification circuit.Voltage-stabilized power supply circuit comprises R ₁, R ₂, R ₃, C ₁, IC ₄, R ₁Be dropping resistor, IC ₄Be adjustable shunting integrated regulator, change R ₂, R ₃Resistance can make output voltage satisfy the requirement of circuit design to supply voltage, C ₁Be power filtering capacitor.

C _L/ U _LTranslation circuit comprises IC ₂, R ₁₅, R ₁₆, R ₁₇, R ₁₈, R ₁₉, C ₃, C ₅, D ₂, C _LR ₁₅, C ₃With IC ₂1 pin connects, R ₁₅The other end connects IC ₂2,3 pin, C ₃The other end connect IC ₂4,5 pin, form the wide pulse signal generator of constant amplitude.R ₁₆With R ₁₇, C _LConnect R ₁₆The other end connects IC ₂13 pin, C _LThe other end connects power-, R ₁₇The other end connects R ₁₈And IC ₂6 pin, R ₁₈Connect IC ₂11 pin and D ₂, D ₂Another termination IC ₂12 pin are formed capacitor pulse and are transferred stretch circuit.IC ₂9 pin, 10 pin link to each other, and 7 pin connect power-, and 14 pin are just connecing power supply.IC ₂8 pin and R ₁₉Connect R ₁₉Another termination C ₅, C ₅The other end connect power-, R ₁₉, C ₅Form signal filter circuit, and from its common port output direct-flow signal voltage U _L

C _ε/ U _εTranslation circuit comprises R ₄, R ₅, R ₆, R ₇, R ₈, C ₂, C ₄, D ₁, C _ε, IC ₁R ₄, C ₂With IC ₁1 pin connects, R ₄The other end and IC ₁2,3 bipods connect C ₂The other end and IC ₁4,5 bipods connect, form the wide pulse signal generator of constant amplitude.R ₅With R ₆, C _εConnect R ₅Another termination IC ₁13 pin, R ₆Another termination IC ₁6 pin, C _εAnother termination power supply negative terminal, R ₇A termination IC ₁6 pin, another termination IC ₁11 pin and D ₁, D ₁Another termination IC ₁12 pin form capacitor pulse and transfer stretch circuit.IC ₁9 pin, 10 pin link to each other.7 pin connect power supply negative terminal, and 14 pin connect power positive end.IC ₁8 pin and R ₈Link to each other R ₈The other end connects C ₄, C ₄Another termination power-, R ₈, C ₄Form signal filter circuit, and from its common port output direct-flow signal voltage U _ε

U _L/ V _LOperational amplification circuit comprises R ₂₀, R ₂₁, R ₂₂, R ₂₃, R ₂₄, R ₂₅, W ₂, C ₇, 1/2IC ₃R ₂₀Two ends meet power-and W respectively ₂, W ₂The other end connect R ₂₁, R ₂₁The other end just connecting power supply, form bleeder circuit, W ₂Movable contact output as the U of fluid to be measured capacity when being zero _L0Balanced voltage.R ₂₂, R ₂₄, IC ₃3 pin link together, R ₂₂The other end connect R ₁₉With C ₅Common port, R ₂₄Another termination power-, R ₂₃, R ₂₅, IC ₃2 pin link together R ₂₃The other end connect W ₂Movable contact, R ₂₅The other end connect IC ₃1 pin is formed U _L/ V _LBoth-end input subtraction amplifying circuit is by IC ₃1 pin output signal voltage V _LC ₇One end connects power-, and an end connects IC ₃1 pin is made signal V _LFilter capacitor.

U _ε/ V _εOperational amplification circuit comprises R ₉, R ₁₀, R ₁₁, R ₁₂, R ₁₃, R ₁₄, W ₁, C ₆, 1/2IC ₃In the circuit, R ₉One termination power anode, the other end connects W ₁, W ₁The other end connect R ₁₀, R ₁₀The other end connect power-, form bleeder circuit, W ₁Movable contact output, the U when being measured as air _εBalanced voltage.R ₁₁One termination W ₁Movable contact, the other end connects IC ₃6 pin and R ₁₄, R ₁₄The other end connects IC ₃7 pin.R ₁₂An end connect R ₈, C ₂Common port, the other end connects IC ₃5 pin and R ₁₃, R ₁₃The other end connects power-, IC ₃8 pin just connecing power supply, 4 pin connect power-, 7 pin output signal voltage V _ε, form U _ε/ V _εBoth-end input subtraction amplifying circuit.C ₆One end connects IC ₃7 pin, the other end connects power supply negative terminal.Make signal V _εFilter capacitor.

Above-mentioned two circuit components all are assembled on the printed on both sides line brush wiring board, and are fixed on integral body of top formation of measuring capacity cell.Vertically be installed in the nearly geometric center of tested container end face by fixing garden dish.Sensor cover 3 is connected with container through gib screw, forms reliable electromagnetic screen.

When fuel tank of vehicle intermediate fuel oil fuel head from h _iRise to h _I+1The time, sensing capacitance C _LMedium in this interval is transformed to fuel oil by air, the dielectric capacitance rate ε that this is interval.Change into ε x, C _LValue change thereupon,

$\mathrm{\&Delta;}{C}_L={\&Integral;}_{\mathrm{hi}}^{\mathrm{hi}+1}2\mathrm{\&pi;}({\mathrm{\&epsiv;}}_x-{\mathrm{\&epsiv;}}_o)\ln \frac{R}{r}\frac{1\left(h\right)}{2\mathrm{\&pi;r}}\mathrm{dh}={\&Integral;}_{\mathrm{hi}}^{h_{i+1}}\frac{{\mathrm{\&epsiv;}}_X-{\mathrm{\&epsiv;}}_O}{r}\ln \frac{R}{r}1\left(h\right)\mathrm{dh}$

$={\&Integral;}_{\mathrm{hi}}^{\mathrm{hi}+1}{K}_{\mathrm{\&epsiv;}}({\mathrm{\&epsiv;}}_x-{\mathrm{\&epsiv;}}_o)s\left(h\right)\mathrm{dh},$ Through C _L/ U _L, U _L/ V _LThe circuit conversion, sensor output voltage is changed to $\mathrm{\&Delta;}{V}_L={\&Integral;}_{\mathrm{hi}}^{\mathrm{hi}+1}{K}_V{K}_C({\mathrm{\&epsiv;}}_x-{\mathrm{\&epsiv;}}_o)s\left(h\right)\mathrm{dh}.$ When measuring the instant actual capacity of fuel tank, integrating range from ho to h, sensor output voltage $V_L={\&Integral;}_{h_0}^h{K}_V{K}_C({\mathrm{\&epsiv;}}_x-{\mathrm{\&epsiv;}}_o)S\left(h\right)\mathrm{dh},$ Consistent with the theoretical calculation method of liquid.

Capacitor C _εBe in below the fuel tank warning pasta, be full of medium oil all the time, again because the sensor medium passage is located at the bottom, so C _εWith C _LMedium be identical all the time, i.e. ε _xEquate.Work as C _εLength when being certain unit length 1, $\mathrm{\&Delta;}{C}_{\mathrm{\&epsiv;}}=2\mathrm{\&pi;}({\mathrm{\&epsiv;}}_x-\mathrm{\&epsiv;o})\ln ,\frac{R}{r}$ Through C _ε/ U _ε, U _ε/ V _εConversion, output voltage can be expressed as V _ε=K _ε(ε _x-ε _o).

In the oil measurement digital display system, make V _LWith

Carry out analog to digital conversion for step-length, get final product $S_L=\frac{V_L}{\frac{\mathrm{V\&epsiv;}}{\mathrm{ks}}}=\mathrm{Ks}{\&Integral;}_{h_0}^h\frac{\mathrm{KvK\&epsiv;}({\mathrm{\&epsiv;}}_X-{\mathrm{\&epsiv;}}_O)}{\mathrm{K\&epsiv;}({\mathrm{\&epsiv;}}_X-{\mathrm{\&epsiv;}}_O)}s\left(h\right)\mathrm{dh}=k{\&Integral;}_{h_0}^{h}s\left(h\right)\mathrm{dh}.$ From formula, as can be seen, when these three parameter integral capacitive transducers are used for the automobile oil mass digital measurement, be applicable to the three parameter compound conditions that become medium, become liquid level, non-constant section container.

Claims (2)

1, the vehicle fuel meter comprises sensing capacitance parts and circuit block with three parameter integral capacitive transducers, it is characterized in that:

A, sensing capacitance parts are a kind of assembled tube type capacity cells, by pipe, inner and outer pipe lead-in wire in dead ring, metal outer pipe, the two-section, fixedly garden dish, radome are formed, metal outer pipe respectively with interior pipe A, interior pipe B formation oil mass sensing capacitor C _LWith oil product permittivity sensing capacitor C _ε, be provided with dead ring between the tube and tube, oil mass sensing capacitor C _LDistribution function l (h) dh of active electrode area of interior pipe A and sectional area distribution function S (h) linear dependence of tested container, wherein l (h) is that the tube wall of interior pipe A is at the distribution function of effective garden of a certain liquid level arc length degree to this liquid level, its implementation is in the corresponding window formula hole of processing on the tube wall and fills typing insulating material, oil product permittivity sensing capacitor C between inner and outer pipes _εInterior pipe B place in the pipe A the lower end, its significant height is no more than the height of vehicle fuel warning pasta, fixedly the garden dish is located at the upper end of sensing capacitance element, fixedly be provided with radome on the dish of garden, total significant height of sensing capacitance element equates with the significant height of tested container, the lower end is provided with oil supply hole, and the upper end is provided with air hole;

B, circuit block constitute voltage-stabilized power supply circuit respectively by adjustable positive output shunt regulator, hex inverter, single supply dual operational amplifier and resistance, electric capacity, diode, the C/U translation circuit, subtraction and scale operation circuit, wherein: voltage-stabilized power supply circuit is by dropping resistor, electric resistance partial pressure signal circuit and adjustable positive output shunt regulator constitute, and press for the sensor internal circuit provides galvanic current;

Two group pulse width modulation type C/U translation circuits are made up of hex inverter and resistance, electric capacity, diode respectively, after connecting stabilized voltage supply, the impulse hunting of two groups of circuit and shaping unit produce the wide rect.p. of constant amplitude that dutycycle equals 1 respectively, and the pulsed modulation part of two groups of circuit is respectively according to C _L, C _εThe size modulations pulse width, make its dutycycle be not equal to 1, and respectively with C _L, C _εBig or small corresponding, electric pulse paraphase, filtering after the paraphase of two groups of circuit, rectification partly will be modulated respectively obtain corresponding direct-flow signal voltage U _L, U _εThereby, realize C respectively _L/ U _L, C _ε/ U _εConversion;

Two groups of operational amplification circuits are made up of single supply dual operational amplifier and resistance, electric capacity, potentiometer, respectively at input U _L, U _εBehind the direct-flow signal voltage, carry out U _L-U _L0, U _ε-U _{ε 0}Computing and ratio are amplified, U _L0And U _{ε 0}The bleeder circuit of being made up of resistance, potentiometer is adjusted to set-point according to design parameter respectively, this circuit output V _L, V _εTwo groups of signal voltages, V _LWith the be integrated into direct ratio of tested fuel tank sectional area to liquid level, V _εBe directly proportional with the oil product permittivity and the measuring voltage corresponding with capacity international unit in the given fuel tank is directly proportional, the two is in the analog to digital conversion circuit of oil mass read out instrument, as aanalogvoltage and reference voltage;

Temperature-compensation circuit adopts thermistor, is used for the change that compensation temperature changes the circuit parameter that causes;

C, circuit component design on a printed on both sides wiring board, and are fixed in the top radome of sensing capacitance element.Insert direct supply by lead, export two groups of measurement signal voltages.

2, by claims 1 described vehicle fuel with three parameter integral capacitive transducers, it is characterized in that:

Hex inverter is 4069 in the foregoing circuit, and dual operational amplifier is 2904, and shunt regulator is 431.

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