CN100501136C

CN100501136C - Engine oil pressure gauge driven by stepper motor

Info

Publication number: CN100501136C
Application number: CNB200710092464XA
Authority: CN
Inventors: 袁强
Original assignee: Chongqing Chuanyi Automation Co Ltd
Current assignee: Chongqing Chuanyi Automation Co Ltd
Priority date: 2007-07-20
Filing date: 2007-07-20
Publication date: 2009-06-17
Anticipated expiration: 2027-07-20
Also published as: CN101092895A

Abstract

This invention discloses an oil pressure meter driven by a stepmotor including a supply converter connected with a micro-controller and track-to-track signal processor connected between a pressure sensor and the microcontroller to level-shift the voltage signal emitted by the pressure sensor to be amplified and output to the microcontroller, a primary voltage source connected between the signal processor and the supply converter providing transfer voltage for the level transfer, a motor driver connected with the output of the microcontroller to amplify the signal output by the microcontroller and output it to the stepmotor connected with the pointer of the pressure meter.

Description

Stepper motor driven fuel level indicator

Technical field

The present invention relates to motor car engine, be specifically related to a kind of stepper motor driven fuel level indicator of detection of engine engine oil pressure.

Background technique

At present the pressure transducer output signal of detection of engine fuel level indicator is-voltage signal of 5mV-50mV, usually the sampled signal of microcontroller is the voltage signal of 0-5V, and only aligning voltage/current signals samples, for the output of above-mentioned pressure transducer-5mV-50mV voltage signal, microcontroller can't directly carry out sample quantization, therefore, need handle and amplify the pressure transducer output signal, making circuit output signal be (0-5V) voltage that microcontroller can be sampled.At above situation, traditional processing method is for adopting dual power supply or adopting positive supply to provide negative supply to the chip of negative supply conversion, to adapt to the processing of double-power source operational amplifier to negative input signal.But,, can't guarantee the linearity if output signal is amplified to the required voltage signal of microcontroller because conventional operation amplification circuit voltage output voltage swing is lower.In order to make operational amplification circuit obtain bigger output amplitude (0-5V); and guarantee the linearity of output signal; usually employings+6V and-the above power supply of 6V powers for operational amplification circuit and microcontroller; but the voltage during microcontroller work is generally+5V; when input voltage is too high, easily micro controller I/O interface is burnt; so in order to protect micro controller I/O interface; need to adopt the limited amplitude protection measure; to solve the voltage mismatch problem; but so can make the entire circuit complexity, cost rises.In addition, linearity adjustment and zero point, the full scale adjustment of gauge hand at present generally adopts potentiometer manually to debug, and this mode needs to debug repeatedly just can reach corresponding required precision, and debug process bothers very much, and adjustment accuracy and repeatability are also relatively poor; And debug time is generally greater than 30 minutes/platform, and As time goes on parameter changes, and is easy to generate zero point and full scale drift, and its linearity changes, and repeating of debugging is poor.

Summary of the invention

For solving the problems of the technologies described above, the invention provides a kind of stepper motor driven fuel level indicator, it adopts single supply to circuit supply, and the sampled signal amplitude of input microcontroller is improved, circuit can guarantee the linearity of this sampled signal, it is simple that the present invention simultaneously has a circuit structure, and cost is lower, good reproducibility, linearity height and the high advantage of reliability.

The object of the present invention is achieved like this: a kind of stepper motor driven fuel level indicator, comprise microcontroller and pressure transducer, pressure transducer is used to respond to the variation in pressure of machine oil and this variation is converted to electrical signal and sends, also comprise the power supply changeover device that is electrically connected with microcontroller, power supply changeover device is converted to the output of microcontroller standard operation voltage with the output voltage of automobile storage battery; And being electrically connected on rail-to-rail signal processor between pressure transducer and the microcontroller, rail-to-rail signal processor is carried out electrical level transfer with the voltage signal that pressure transducer sends, and outputs to microcontroller after doing to amplify; And being electrically connected on reference voltage source between rail-to-rail signal processor and the power supply changeover device, this reference voltage source provides the migration voltage of electrical level transfer for rail-to-rail signal processor; And the motor driver that is electrically connected with the microcontroller output terminal, output to the stepper motor that is connected with gauge hand after the electrical signal amplification of motor driver with microcontroller output.

Adopted such scheme, the power supply changeover device that is electrically connected with microcontroller, by single supply to circuit supply, the output voltage of automobile storage battery can be converted to the output of microcontroller standard operation voltage, output to the voltage of the voltage of rail-to-rail signal processor and microcontroller when identical, rail-to-rail signal processor output voltage amplitude is improved, to improve the linearity of sampled signal quantization resolution, assurance sampled signal; In the time of also can preventing overtension simultaneously micro controller I/O interface is burnt; And need not adopt the limited amplitude protection measure to solve the voltage mismatch problem, cause circuit structure to be oversimplified, cost of production reduces.Be electrically connected on the rail-to-rail signal processor between pressure transducer and the microcontroller, the voltage signal that rail-to-rail signal processor sends pressure transducer is carried out by negative to positive electrical level transfer, can avoid conventional method to adopt positive supply to provide negative supply, circuit structure is simplified to the chip of negative supply conversion; And can reduce the electrical signal distortion of output, and the gain of the linearity strengthened, satisfy microcontroller and sensor signal is carried out sample quantization handle.Be made up of electrical level transfer amplification circuit and voltage follower in the rail-to-rail signal processor, voltage follower can play buffer function to the signal of electrical level transfer amplification circuit output, not only can improve load capacity, and can isolate than heavy load.

Be electrically connected on the reference voltage source between rail-to-rail signal processor and the power supply changeover device, reference voltage source can be rail-to-rail signal processor necessary migration voltage is provided; Comprise one the three adjustable shunting a reference source of end in the reference voltage source, it is low that shunting a reference source that three ends are adjustable not only possesses the temperature correction temperature coefficient, and have good thermal stability and decoupling performance, with accentuator stability.In addition, three ends are adjustable, and the reference potential of a 2.5V is contained in shunting a reference source inside, so when when the REF of the adjustable shunting a reference source of three ends end is introduced the output feedback, can pass through the shunting from negative electrode to the anode wide range, the control output voltage.

The SPI output interface of microcontroller is electrically connected a V/I converter,linear, pass through linear transform circuit, the voltage signal that microcontroller is handled is converted to the current signal output of 4-20mA, and the long-range signal input that is transported to other unit of motor as these unit.

The pin 11 of microcontroller and pin 12 through lead draw respectively with circuit board on be provided with two be used for that adjust zero point or full scale is adjusted joint weld, because pressure transducer shows as resistance variations, adopt the standard pressure generator to replace potentiometer, connect the full scale adjustment or adjust interface zero point, by the voltage sample of microcontroller to current zero point or full scale correspondence, by the Automatic Program correction of presetting in the microcontroller, realize adjustment to pressure gauge zero point or full scale.Therefore, adjust at zero point of the present invention and the full scale adjustment simple, good reproducibility during adjustment, and the whole adjustment time less than 2 minutes, and can reduce the inconsistent error of bringing of parameter of handling time and element, guarantee to adjust precision.

The present invention carries out testing experiment on the refuelling truck in the open air, once by corresponding test, has realized the remote transmission of linear indication of pressure gauge and data, satisfies the high reliability of its field work.This manometric linearity is higher than the parameter request of the field work in the test, and the current signal of output 4-20mA is gathered it being used for PLC, and precision meets the demands fully, and the data stabilization of transmission is reliable.

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.For the person of ordinary skill in the field, from detailed description of the invention, above-mentioned and other purposes of the present invention, feature and advantage will be apparent.

Description of drawings

Fig. 1 is the circuit block diagram of the stepper motor driven fuel level indicator of the present invention;

Fig. 2 is the circuit diagram of the power supply changeover device among Fig. 1;

Fig. 3 is the schematic representation of the dial plate indicating circuit backlight among Fig. 1;

Fig. 4 is the circuit diagram of the reference voltage source among Fig. 1;

Fig. 5 is the circuit diagram of the rail-to-rail signal processor among Fig. 1;

Fig. 6 is the circuit diagram that the motor driver among Fig. 1 is connected with microcontroller;

Fig. 7 is the circuit diagram of the V/I converter,linear among Fig. 1.

Embodiment

With reference to Fig. 1 and Fig. 7, stepper motor driven fuel level indicator of the present invention has: microcontroller U5, pressure transducer (pressure transducer is not shown in the drawings), power supply changeover device, rail-to-rail signal processor, reference voltage source, motor driver, V/I converter,linear.Pressure transducer is used to respond to the variation in pressure of machine oil and this variation is converted to electrical signal and sends, and power supply changeover device is electrically connected with microcontroller, the output voltage of automobile storage battery is converted to microcontroller standard operation voltage exports; Be electrically connected rail-to-rail signal processor between pressure transducer and the microcontroller, the voltage signal that pressure transducer sends is carried out electrical level transfer, and output to microcontroller after doing to amplify; Be electrically connected reference voltage source between rail-to-rail signal processor and the power supply changeover device, the migration voltage of electrical level transfer is provided for rail-to-rail signal processor; Motor driver is electrically connected with microcontroller output, outputs to the stepper motor that is connected with gauge hand after the electrical signal amplification with microcontroller output; The SPI output interface of microcontroller is electrically connected a V/I converter,linear, and the voltage signal that the V/I converter,linear is exported microcontroller converts current signal to and is used for long-range conveying.

With reference to Fig. 2, the pin 49 of microcontroller U5 is electrically connected with power supply changeover device, and power supply changeover device is converted to the output of microcontroller standard operation voltage with the output voltage of automobile storage battery.The output voltage V BAT voltage range of automobile storage battery is that 20V is to 28V.Power supply changeover device is a trifocal adjustable voltage-regulating ic device IC1, and IC1 adopts the LM317LH chip.VBAT is connected with the input pin 3 of IC1 by diode in series D1, current-limiting resistance R1, and capacitor C 3 and electrochemical capacitor C4 are connected in parallel between the pin 3 and ground of IC1.Diode D1 negative electrode is drawn a power supply V1, and this power source voltage is 24V.Resistance R 1 constitutes limiting filter circuit with capacitor C 3, C4, makes trifocal adjustable voltage-regulating ic device avoid being subjected to burst of pulses to do.Resistance R 5, R7 and capacitor C 5 are connected in parallel between the pin 1 and ground of trifocal adjustable voltage-regulating ic device IC1, and the pin 2 of trifocal adjustable voltage-regulating ic device is connected with its pin 1 by resistance R 3.Electrochemical capacitor C1 and C2 are connected between the pin 2 and ground of trifocal adjustable voltage-regulating ic device IC1, electrochemical capacitor C1 and C2 are used for energy storage, behind power cut-off, energy needed in the time of can guaranteeing that microcontroller is preserved corresponding data and stepper motor and resetted, making has enough energy to make the step motor drive gauge hand get back to zero graduation after having a power failure.Power supply changeover device is connected with microcontroller, rail-to-rail signal processor, dial plate indicating circuit backlight, motor driver and V/I converter,linear respectively by the output branch road, provides required power supply to each circuit unit.

Supply voltage is after power supply changeover device conversion, and by the voltage VCC of output pin 2 outputs one 5V of trifocal adjustable voltage-regulating ic device IC1, by the parameter of selected element, the output voltage that can obtain power supply changeover device VCC according to the following step is:

VCC＝1.25V(1+(R5//R7)/R3+Iadj*(R5//R7)

Because the adjusting electric current of IC1 is very little, ignores the influence of Iadj, then the output value of circuit is approximately:

VCC＝1.25V(1+(R5//R7)/R3)

Present embodiment resistance R 5=1.5k, R7=20K, R3=470

VCC=5.01V then

With reference to Fig. 1 and Fig. 3, manometric dial plate indicating circuit backlight is made up of the branch road of three parallel connections of parallel connection, branch road one is made of resistance R 2 series connection light emitting diode D2, D3, branch road two is made of resistance R 4 series connection light emitting diode D5, D6, branch road three is made of resistance R 6 series connection light emitting diode D7, D8, and resistance R 2, R4, R6 play metering function for place branch road separately.Dial plate indicating circuit one end backlight is connected with V1, and the other end is connected with ground by diode D4.For the brightness that guarantees light emitting diode changes little, the series connection number that reduces light emitting diode among the present invention increases the resistance of current-limiting resistance, make reducing of electric current influence by voltage, as size of current in the branch road of R2, D2, D3 composition is (V1-VD2-VD3)/R2=(24V-3.4V)/4.7K=5mA, and electric current is about 5.5mA when mains voltage variations is 28V; Electric current is about 4.5mA when mains voltage variations is 20V, and in ± 0.5mA, the brightness that has guaranteed light emitting diode changes and meets the demands whole electric current with the variation of voltage.

With reference to Fig. 1 and Fig. 4, be electrically connected on the reference voltage source between rail-to-rail signal processor and the power supply changeover device, this reference voltage source provides the migration voltage of electrical level transfer for rail-to-rail signal processor.Comprise one the three adjustable shunting a reference source of end IC3 in the reference voltage source, shunting a reference source that three ends are adjustable adopts the TL431ALCP cake core.The pin 3 of shunting a reference source that three ends are adjustable is connected with ground, and its pin 2 is connected with stabilized power supply by current-limiting resistance R28, and capacitor C 29 is connected in parallel between the

2,3 of the adjustable shunting a reference source of three ends with two resistance R 31, R34 connecting.The voltage output pin 1 of shunting a reference source that three ends are adjustable is connected electrically between resistance R 31 and the R34, the voltage V2 of the output 5V of reference voltage source draws by resistance R 31 1 ends, and by the series connection divider resistance R30, R33 be connected with ground, resistance R 33 two ends connect a capacitor C 33.The voltage of the output 5V of reference voltage source is through resistance R 30 dividing potential drops, and after capacitor C 30 filtering, one of output at resistance R 33 two ends is a reference voltage V 5, and the size of this voltage is:

5V*R33/(R33+R30)＝5V*390/2390＝0.82V

Resistance R 33 1 ends are electrically connected by the homophase input pin of the operational amplifier U4C in resistance R 29 and the rail-to-rail signal processor, for rail-to-rail signal processor provides electrical level transfer required migration voltage.The reference potential of a 2.5V is contained in the inside of shunting a reference source that three ends are adjustable, when introducing the output feedback at its pin 1 (REF end), makes it control output voltage by the shunting from negative electrode to the anode wide range.When the resistance of R31 and R34 was determined, both introduced feedback to the dividing potential drop of V2, if V2 increases, feedback quantity increases, and the shunting of TL431ALCP also just increases, from and cause V2 to descend, this moment V2=(1+R31/R34) Vref (Vref is the chip internal reference voltage, and its size is 2.5V).Select the free voltage output in can obtaining from 2.5V to the 36V scope of the value of different R31 and R34, especially, when R31=R34, V2=5V.R28 plays the restriction electric current, and maximum current is (24V-5V)/2K=9.5mA, has guaranteed that maximum input current is less than TL431ALCP maximal work electric current.

With reference to Fig. 1 and Fig. 5, be electrically connected on the rail-to-rail signal processor (Rail-To-Rail) between pressure transducer and the microcontroller U5, rail-to-rail signal processor is carried out electrical level transfer with the voltage signal that pressure transducer sends, and outputs to microcontroller after doing to amplify.Rail-to-rail signal processor is made up of electrical level transfer amplification circuit and the voltage follower that is electrically connected with the electrical level transfer amplification circuit.The electrical level transfer amplification circuit amplifies the signal of sensor output, and by the voltage that voltage-reference provides above-mentioned amplifying signal is carried out electrical level transfer.The electrical level transfer amplification circuit comprises operational amplifier U4A, U4C, U4D, the

homophase input pin

3,12 of operational amplifier U4A and U4D connects with the connector J2 that is connected pressure transducer, and two output terminals of pressure transducer are connected with the

1,2 of connector J2 respectively.Pressure transducer is used to respond to the variation in pressure of machine oil and this variation is converted to electrical signal and sends, pressure transducer adopts the pressure transducer of strain resistance type among the present invention, the electric bridge that it is made of four strain resistors, this electric bridge be transformed to the variation in pressure of machine oil-the voltage output of 5mV-50mV.The pin 4 of connector J2 is connected with ground, and its pin 3 is connected with the output voltage V 2 of reference voltage source.The reverse input pin 2 of operational amplifier U4A is connected with the reversed input pin 13 of operational amplifier U4D by resistance R 20, the R24 of series connection, resistance R 22 and capacitor C 21 are connected in parallel between operational amplifier U4A output pin 1 and the reversed input pin, the output pin 1 of operational amplifier U4A is connected with operational amplifier U4C reversed input pin 9 by resistance R 21, the homophase input pin 3 of operational amplifier U4A also is connected with ground by capacitor C 19, and its pin 11 is connected with ground.Resistance R 23 and capacitor C 25 are connected in parallel between operational amplifier U4D output pin 14 and the reversed input pin 13, the homophase input pin of operational amplifier U4D also is connected with ground by capacitor C 28, operational amplifier U4D output pin is connected with an end of resistance R 25, and the other end of resistance R 25 connects the homophase input pin 10 of voltage-reference and operational amplifier U4C respectively.Resistance R 19 and capacitor C 20 are connected in parallel between operational amplifier U4C output pin and its reversed input pin, and operational amplifier U4C pin 4 is connected with VCC respectively, and are connected with ground by capacitor C 22; Operational amplifier U4C is connected with voltage follower by resistance R 42.Voltage follower is used for the voltage signal of electrical level transfer amplification circuit output is cushioned, voltage follower is made up of operational amplifier U4B, resistance R 42 and resistance 18, wherein, resistance R 18 is connected between the signal output pin 7 and reversed input pin 6 of operational amplifier U4B, resistance R 42 is connected between operational amplifier U4B homophase input pin and the electrical level transfer amplification circuit output end, and operational amplifier U4B is connected with 41 pin of microcontroller by resistance R 40.Operational amplifier U4A, U4B, U4C, U4D all adopt LMX324 model chip.

The voltage signal (VOUT) that can obtain the output of electrical level transfer amplification circuit according to the following step is: the magnification factor of prime operational amplifier U4A, U4D: A1=(1+ (R22+R23)/(R20+R24)) (1)

The input voltage of pressure transducer is: VIN=V1IN-V2IN, obtain prime operational amplifier output voltage by formula (1), and its value size is:

V3-V4＝A1*VIN＝VIN*(1+(R22+R23)/(R20+R24)) (2)

The voltage amplification factor of operational amplifier U4C is

A2＝R19/R21 (3)

Know that according to the voltage superposition principle output voltage was when sensor was imported separately:

VOUT1＝(A1*VIN)*A2

＝(VIN*(1+(R22+R23)/(R20+R24)))*R19/R21 (4)

When reference potential acted on the second level separately, output voltage was:

VOUT2＝R25/(R25+R29)*V4*(1+R19/R21)

By R19=R25, R21=R29 obtains VOUT2=V5; Know VOUT2=V5=0.82V by the reference potential computing

Then total voltage is output as:

VOUT＝VOUT2+VOUT1＝(VIN*(1+(R22+R23)/(R20+R24))*R19/R21+V5(5)

By in the formula (5) as can be seen, when input voltage is negative voltage, chooses suitable reference voltage V 4 and make output voltage, thereby realize the migration of level greater than 0V.Output voltage finally can be adjusted between the 0-5V.

When sensor be input as-during 5mV, the output voltage that sensor is done the time spent separately is:

R20＝R24＝7.5k，R22＝R23＝100k，R19＝51k，R21＝10k

Output voltage is VOUT1=-0.36V (6)

The overall output voltage of circuit is after adding bias voltage:

VOUT＝VOUT2+VOUT1＝0.82-0.36V＝0.46V

When sensor input position+50mV, the output voltage that sensor is done the time spent separately is:

VOUT1＝3.6V (7)

The overall output voltage of circuit is after adding bias voltage:

VOUT＝VOUT2+VOUT1＝0.82+3.6V＝4.42V (8)

Learn by (7) formula and (8), after rail-to-rail signal processor processes, whole output voltage at 0.46V between the 4.42V, with the output voltage of pressure transducer from-0.36V to 3.6V to moving to 0.46V to the 4.42V, realized electrical level transfer and to the requirement of microcontroller input voltage.

With reference to Fig. 1 and Fig. 6,, output to the stepper motor that is connected with gauge hand after the electrical signal amplification of motor driver with microcontroller output with the motor driver that the microcontroller output terminal is electrically connected.Microcontroller U5 adopts the 68HC908LJ12 cake core, 11 pin of microcontroller and 12 pin through lead draw respectively with circuit board on be provided with two be used for the full scale adjustment or adjust interface H2 welding zero point, H2 is two holes on circuit board.After microcontroller U5 received the voltage signal of rail-to-rail signal processor, its output signal was amplified by the motor driver electric current, offers the stepper motor M1 that is connected with gauge hand.Motor driver is made of four AND NOT gate U3A, U3B, U3C, UD, the output pin 45,46,59,60 of microcontroller is corresponding respectively to be connected with U3D, U3C, U3B, U3A, the output terminal of each AND NOT gate is corresponding respectively to be connected with the

terminal

1,2,3,4 of stepper motor, and each AND NOT gate all adopts the MC74ACT08 chip.

With reference to Fig. 1 and Fig. 7, the SPI output interface of microcontroller is electrically connected a V/I converter,linear, converts the voltage signal of microcontroller output to current signal and is used for long-range conveying.The V/I converter,linear comprises D/A converter U1, one-level operational amplifier U8B, the first transistor Q5, two-level operating amplifier U8A and the second transistor Q6.D/A converter U1 is connected with microcontroller SPI interface, the SPI interface of microcontroller is its

17,25,26,29, the

1,2,3,4 of D/A converter U4 is corresponding respectively to be connected with the

25,17,29,26 of microcontroller, 10 position digital signals of microcontroller SPI interface output is converted into the analog voltage signal of 0.4V-2.0V.D/A converter U1 is one 10 figure place weighted-voltage D/A converter, and D/A converter adopts the TLC5615 cake core.The pin 5 of D/A converter U4 is connected with ground, and its pin 6 is a feedback input end, and its pin 8 is connected with VCC, and is connected with ground by capacitor C 9, and its pin 7 is connected with the homophase input pin 5 of one-level operational amplifier U8B by resistance R 8.One-level operational amplifier U8B reversed input pin 6 is connected with ground by resistance R 54 in the lump with the emitter of the first transistor Q5, and its output pin 7 is connected with the base stage of the first transistor Q5.The collector electrode of the first transistor Q5 is connected with the output terminal V1 of power supply changeover device by resistance R 53, also can directly be connected with automobile bottle pond output terminal, and resistance R 53 is connected with V1 by reference diode D18.The collector electrode of the first transistor Q5 is connected with the homophase input pin of two-level operating amplifier U8A; The reversed input pin of two-level operating amplifier U8A is connected with V1 by resistance R 55 in the lump with the emitter of the second transistor Q6, the output pin 1 of two-level operating amplifier U8A is connected with the base stage of the second transistor Q6, and the second transistor Q6 collector electrode is connected with connector JP2.One-level operational amplifier U8B, the first transistor Q5 and resistance R 54 are formed a Constant Current Load, and the size of electric current is by the 5 pin Control of Voltage of U8B.The input current of two-level operating amplifier U8A is minimum, electric current that resistance R 53 flows through and the electric current on the R54 equate, the resistance of resistance R 53 and R54 equates, the voltage at resistance R 54 two ends and R53 both end voltage equate, the output voltage of the voltage at resistance R 54 two ends and D/A converter U1 equates at this moment, and scope is 0.4V-2V.Because the characteristic of amplifier, two terminal potentials of the input after stable equate, the voltage of resistance R 55 and R54 both end voltage equate, the voltage at resistance R 55 two ends and the output voltage of D/A converter equate, the voltage of resistance R 55 is controlled by the output voltage of D/A converter, output current I scope is that (0.4V/R55=4mA, 2.0V/R55=20mA), electric current and voltage are the linear conversion relation to 4-20mA.Realized the linear conversion of voltage and current V-I, and by connector J2 output, the 4-20mA of output is used for the remote transmission of temperature signal and delivers to the standard input signal of other unit of motor as these unit.Concrete connecting means is during use: 2 pin of connector J2 be connected publicly, 1 pin of J2 is connected to the current input terminal of other parts.

Working procedure of the present invention is: pressure transducer is converted into the variation in pressure of induction-output of 5mV-50mV voltage signal, the amplifier that this signal is formed by operational amplifier U4A, U4C, U4D and relevant peripheral resistance capacitance amplifies the small-signal of sensor, and by voltage-reference provide the migration voltage carry out electrical level transfer, make voltage signal after the amplification between 0V-5V, this signal is formed voltage follower after buffering by U4B, R42, R18, be sent to microcontroller pin 41 (ADIN), enter the A/D converter of microcontroller inside.A/D converter through microcontroller carries out sample quantization to the aanalogvoltage of importing, and is converted to integer value.And by software algorithm, the one tunnel is converted to the drive waveforms of stepper motor, and drives by motor driver, is sent to the line bag of stepper motor M1, and stepper motor M1 drives the pointer rotation, the force value of indication machine oil on linear dial.10 position digital signals are exported by the SPI interface of microcontroller in another road of data that sampling obtains, be converted into the voltage signal of 0.4V-2.0V by 10 D/A converter U1 (TLC5615), this voltage signal is converted to current signal through one-level operational amplifier U8B, the first transistor Q5 and resistance R 54 composition Constant Current Loads, electric current and voltage are the linear conversion relation, by two-level operating amplifier U8A this electric current I is enlarged into 4-20mA (0.4V/R55=4mA, 2.0V/R55=20mA), and by connector H1 output.The 4-20mA of output is used for the remote transmission of temperature signal and delivers to the signal input of other unit of motor as these unit

Adopt the present invention to gauge hand adjustment process at zero point to be: pressure transducer is connected with the standard pressure generator, and the

1,2 of connector J2 is connected with two output terminals of pressure transducer respectively, adjusts the standard pressure generator, and making its delivery pressure is zero; 2 pin of H2 (via hole that is connected with microcontroller pin 11 by lead) are shorted to ground with lead, microcontroller is immediately to the voltage sample of correspondence at current zero point, as manometric initial zero, with the deduction voltage deviation at zero point, the program that presets by microcontroller inside directly returns to zero.

Adopt the present invention to be: pressure transducer is connected with the standard pressure generator to gauge hand full scale adjustment process, the

1,2 of connector J2 is connected with two output terminals of pressure transducer respectively, adjust the standard pressure generator, making its delivery pressure is zero, and at this moment the detected force value of pressure transducer is zero; 1 pin of H2 (via hole that is connected with microcontroller pin 12 by lead) is shorted to ground with lead, microcontroller is immediately to the voltage sample of correspondence at current zero point, as manometric initial zero, with the deduction voltage deviation at zero point, the program that presets by microcontroller inside directly returns to zero.By

1,2 combinations that H2 is set, can also can carry out the linear multi correction by the program that presets in the microcontroller.The adjustment method at method and full scale, zero point is identical.

Though the present invention discloses as above with preferred embodiment; right its is not in order to limit the present invention; any person of ordinary skill in the field; without departing from the spirit and scope of the invention; when can doing a little change and improvement, so the present invention's protection domain is as the criterion when looking the claim person of defining.

Claims

1. stepper motor driven fuel level indicator, comprise microcontroller and pressure transducer, pressure transducer is used to respond to the variation in pressure of machine oil and this variation is converted to electrical signal and sends, it is characterized in that: also comprise the power supply changeover device that is electrically connected with microcontroller, power supply changeover device is converted to the output of microcontroller standard operation voltage with the output voltage of automobile storage battery; And being electrically connected on rail-to-rail signal processor between pressure transducer and the microcontroller, rail-to-rail signal processor is carried out electrical level transfer with the voltage signal that pressure transducer sends, and outputs to microcontroller after doing to amplify; And being electrically connected on reference voltage source between rail-to-rail signal processor and the power supply changeover device, this reference voltage source provides the migration voltage of electrical level transfer for rail-to-rail signal processor; And the motor driver that is electrically connected with the microcontroller output terminal, output to the stepper motor that is connected with gauge hand after the electrical signal amplification of motor driver with microcontroller output.

2. stepper motor driven fuel level indicator according to claim 1, it is characterized in that: the SPI output interface of described microcontroller is electrically connected a V/I converter,linear, and the voltage signal that the V/I converter,linear is exported microcontroller converts current signal to and is used for long-range conveying.

3. stepper motor driven fuel level indicator according to claim 2 is characterized in that: described V/I converter,linear comprises D/A converter U1, one-level operational amplifier U8B, the first transistor Q5, two-level operating amplifier U8A and the second transistor Q6; D/A converter U1 is connected with microcontroller SPI interface; The homophase input pin 5 of one-level operational amplifier U8B is connected with D/A converter output pin 7 by resistance R 8, one-level operational amplifier reversed input pin 6 is connected with ground by resistance R 54 in the lump with the emitter of the first transistor Q5, and its output pin 7 is connected with the base stage of the first transistor Q5; The first transistor Q5 collector electrode is connected with stabilized power supply V1 by resistance R 53, and is connected with the homophase input pin of two-level operating amplifier U8A; The reversed input pin of two-level operating amplifier U8A is connected with the 24V power supply by resistance R 55 in the lump with the emitter of the second transistor Q6, the output pin 1 of two-level operating amplifier U8A is connected with the base stage of the second transistor Q6, and the second transistor Q6 collector electrode is connected with connector H1.

4. stepper motor driven fuel level indicator according to claim 1, it is characterized in that: described rail-to-rail signal processor is made up of electrical level transfer amplification circuit and the voltage follower that is electrically connected with the electrical level transfer amplification circuit, wherein the electrical level transfer amplification circuit amplifies the signal of sensor output, and by the voltage that voltage-reference provides above-mentioned amplifying signal is carried out electrical level transfer; Voltage follower is used for the voltage signal of electrical level transfer amplification circuit output is cushioned.

5. stepper motor driven fuel level indicator according to claim 4, it is characterized in that: described electrical level transfer amplification circuit comprises operational amplifier U4A, U4C, U4D, the homophase input pin of operational amplifier U4A and U4D connects with the connector J2 that is connected pressure transducer, the reverse input pin of operational amplifier U4A is by resistance R 20, R24 is connected with the reversed input pin of operational amplifier U4D, resistance R 22 and capacitor C 21 are connected in parallel between operational amplifier U4A output pin and the reversed input pin, and the output pin of operational amplifier U4A is connected with operational amplifier U4C reversed input pin by resistance R 21; Resistance R 23 and capacitor C 25 are connected in parallel between operational amplifier U4D output pin and the reversed input pin, operational amplifier U4D output pin is connected with an end of resistance R 25, and the other end of resistance R 25 connects the homophase input pin 10 of voltage-reference and operational amplifier U4C respectively; Resistance R 19 and capacitor C 20 are connected in parallel between operational amplifier U4C output pin and its reversed input pin, and operational amplifier U4C is connected with voltage follower by resistance R 42.

6. stepper motor driven fuel level indicator according to claim 4, it is characterized in that: described voltage follower is made up of operational amplifier U4B, resistance R 42 and resistance 18, wherein, resistance R 18 is connected between the signal output pin 7 and reversed input pin 6 of operational amplifier U4B, resistance R 42 is connected between operational amplifier U4B in-phase input end and the electrical level transfer amplification circuit output end, and operational amplifier U4B is connected with 41 pin of microcontroller by resistance R 40.

7. stepper motor driven fuel level indicator according to claim 1, it is characterized in that: comprise one the three adjustable shunting a reference source of end IC3 in the described reference voltage source, the pin 3 of the adjustable shunting a reference source of this three end is connected with ground, its pin 2 is connected with power supply changeover device by current-limiting resistance R28, capacitor C 29 and two resistance R 31 of connecting, R34 is connected in parallel on the pin 2 of the adjustable shunting a reference source of three ends, between 3, the voltage output pin 1 of shunting a reference source that three ends are adjustable is connected electrically between resistance R 31 and the R34, reference voltage source is drawn output voltage V 2 by resistance R 31 1 ends, and divider resistance R30 by connecting, R33 is connected with ground, and resistance R 33 1 ends are electrically connected with rail-to-rail signal processor by resistance R 29.

8. stepper motor driven fuel level indicator according to claim 1 is characterized in that: described power supply changeover device is a trifocal adjustable voltage-regulating ic device.

9. stepper motor driven fuel level indicator according to claim 1 is characterized in that: the pin 11 of described microcontroller and pin 12 through lead draw respectively with circuit board on be provided with two be used for that adjust zero point or full scale is adjusted joint weld.

10. according to any described stepper motor driven fuel level indicator of claim 1 to 9, it is characterized in that: described motor driver is made of four AND NOT gate, and each AND NOT gate all adopts the MC74ACT08 cake core.