CN2750301Y

CN2750301Y - Stepping motor type thermometer

Info

Publication number: CN2750301Y
Application number: CNU2004200769059U
Authority: CN
Inventors: 刘海泉
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-10-12
Filing date: 2004-10-12
Publication date: 2006-01-04
Anticipated expiration: 2014-10-12
Also published as: WO2006039861A1

Abstract

The utility model relates to a step motor type thermometer which comprises an instrument cover (1), a dial (2), a circuit board (3), a night lighting circuit (4) and a housing (5). The utility model is characterized in that the circuit board (3) comprises a temperature measurement loop which is composed of a thermistor temperature sensor, a processing circuit, a stabilized voltage power supply, a single chip computer, a step motor and a pointer, wherein the thermistor temperature sensor, the processing circuit, the single chip computer and the step motor are sequentially electrically connected; the stabilized voltage power supply is electrically connected with the processing circuit and the single chip computer through an output branch circuit; the single chip computer is electrically connected with the step motor; besides, the processing circuit is connected with the single chip computer.

Description

The step motor type thermometer

Technical field

The utility model relates to a kind of automobile thermometer, and more particularly it is a kind of step motor type thermometer.

Background technology

The high temperature automotive instrument will obtain application more and more widely now; high-power automatic gear-box as U.S. ALLISON company; price is higher; fluid in the cooling wheel box generates heat easily; the too high damage that causes wheel box easily of oil liquid temperature; in order to protect wheel box, need a kind ofly to be quick on the draw, high reliability, high-precision thermometer, measuring temperature will be near 200 ℃.

Traditional metering circuit adopts thermistor and moving magnetic filed to cooperate more, and temperature is measured.There is a lot of shortcomings in this structure: as the non-linear and discreteness of moving magnetic filed, non-linear and the discreteness of thermistor, the fluctuation of power supply, sensor and moving magnetic filed all will flow through bigger electric current and (easily cause heating, further make misregister, when serious in addition because temperature is too high and on fire), at accuracy requirement higher and when measuring high temperature all can't by before the circuit of design meet the demands; So existing automobile thermometric instrument can not accurately be measured (10% all is difficult to satisfy), in addition since the temperature-resistance characteristic of thermistor present index law and successively decrease, very little at temperature of reaction changes during temperature more than 120 ℃ resistance change rate, during high temperature thermistor flow through electric current when excessive performance also unstable, so thermistor is joined the moving-magnetic type pointer thermometer that the method for moving magnetic filed is difficult to make high temperature (more than 160 ℃), pin-point accuracy, circuit in the past is can only be at accuracy requirement not high and measure under the not high occasion of temperature and use, as the measured automobiles water temperature etc.

In order to solve the problems of measurement of relative higher temperature on the automobile, the patent No. is 03241068.9 moving magnetic pointer-type thermometer employing thermal resistance sensor, microprocessor and electronic technology and moving magnetic filed way of combining are measured and indication high temperature, and technical had a bigger progress; But still exist some problems as follows: (1) thermal resistance PT100 temperature sensor uses needs to adopt two-wire on automobile, can not pass through the direct ground connection of sensor one end, use inconvenience, and the anti-vibration performance of thermal resistance PT100 is poor than thermistor, the difficult automotive environment that is fit to; PT100 temperature sensor input computing machine after the circuit that R21, R22, R23 form enters the operational amplifier amplification is measured, and the electric signal of its representation temperature adopts the two-wire transmission, uses inconvenience on the automobile, does not adopt double wire system to be vulnerable to again disturb.(2) still adopted moving magnetic filed, the poor reliability of moving magnetic filed, long-term vibration can cause instrument moving magnetic filed hair fastener, misregister etc.

Summary of the invention

The purpose of this utility model is to overcome the weak point of above-mentioned background technology and a kind of step motor type thermometer is provided.It can indicate 0 ℃-200 ℃ temperature range, and has quite high accuracy.

The purpose of this utility model reaches by following measure: the step motor type thermometer, it comprises instrument mask 1, index dial 2, circuit board 3, night light 4, shell 5, and described circuit board 3 comprises the temperature survey loop that thermistor temperature sensor, treatment circuit, stabilized voltage supply, one-chip computer, stepper motor and pointer are formed; Thermistor temperature sensor, treatment circuit, one-chip computer, stepper motor are electrically connected successively, stabilized voltage supply is electrically connected with treatment circuit, one-chip computer by the output branch road, one-chip computer is electrically connected with stepper motor, and treatment circuit is connected with one-chip computer.

In technique scheme, also has an EEPROM electricity erasable memorizer in the temperature survey loop of described circuit board 3, described EEPROM electricity erasable memorizer is electrically connected with output branch road, the treatment circuit of stabilized voltage supply, and the EEPROM electricity erasable memorizer is electrically connected with one-chip computer.

In technique scheme, described one-chip computer has the interface that connects calibration system and/or audio alert.

In technique scheme, described one-chip computer has and demarcates the interface that PC is connected.

In technique scheme, described circuit board 3 is two layers, and last layer circuit board and lower circuit plate are electrically connected by conductive pole 6 and lead 7.

In technique scheme, described stepper motor 8 passes axle 9 and is connected with index dial 2 with self-tapping screw 10, index dial 2 is positioned on the layer circuit board, night light 4 is positioned on the lower circuit plate or directly at index dial 2, the input of power supply, temperature sensor, night illumination power supply also connects by conductive pole.

In technique scheme, described instrument mask 1 is fixing by clamp 11 with shell 5.

The utlity model has following advantage: 1. overcome the defective that former circuit needle deflection error is big, current sinking is big, also solved the problem of moving magnetic pointer thermometer high temperature measurement poor accuracy simultaneously.2. the self calibrating function realized of the utility model and PC communication has been eliminated the inconsistent error of bringing of electronic component parameter, and the accuracy of measurement of instrument is greatly improved; Memory function with nominal data.3. the utlity model has the function and the audio alert function of the pointer warning of sensor broken string, shorted to earth.4. solved the inaccurate and dangerous problem of instrument that the heating of former circuit sensor and moving magnetic filed causes.5. can indicate 0 ℃-200 ℃ temperature range, have quite high accuracy (3%), manufacturing process is simple.

Description of drawings

Fig. 1 is the functional-block diagram (contain and demarcate part) of the utility model step motor type thermometer;

Fig. 2 is the circuit diagram of the utility model step motor type thermometer;

Fig. 3 is the structural representation of the utility model step motor type thermometer.

Embodiment

Describe performance of the present utility model in detail below in conjunction with accompanying drawing:

Among the figure 1 be instrument mask, 2 for index dial, 3 for circuit board, 4 for night light, 5 for shell, 6 for conductive pole, 7 for lead, 8 for stepper motor, 9 for axle, 10 for self-tapping screw, 11 for clamp.

From accompanying drawing as can be known: the core section the utility model step motor type thermometer physical construction adopts hierarchy, can dwindle the volume of instrument like this, upper strata, lower floor are that circuit board, index dial are positioned on the layer circuit board, and night light is positioned on the lower circuit plate or directly to be done on index dial.Circuit board adopts circular board structure of circuit, sets up electrical connection between the two-tier circuit plate by lead and conducting rod, and the input of power supply, temperature sensor, night illumination power supply is also by the conduction connecting link.

Deflection, alarm mechanism that the utility model step motor type thermometer circuit board is made up of thermistor temperature sensor and treatment circuit, all-night circuit and illumination LED, voltage-stabilized power supply circuit, one-chip computer, EEPROM electricity erasable memorizer, voice alarm circuit, stepper motor and pointer are formed.

During the work of the utility model step motor type thermometer, the resistance of temperature of reaction variation is become the voltage of 0-5V by the sensor treatment circuit, use the one-chip computer measuring voltage then, the deflection angle that obtains the measurement AD value under some key point temperature and need by the way of demarcating, and the AD value that these key points are measured and the deflection angle of needs " are remembered ".Enter the EEPROM electric erasable storage chip of one-chip computer, instrument is in work, whenever measure an AD value, just can calculate corresponding deflection angle by the AD value, if it is identical with the temperature of these calibration points, just get these needle deflection angles, if it is unequal, then according to the scope of AD value, linearization is carried out in segmentation, uses the way of linear interpolation then, obtain corresponding deflection angle, thereby the inflection point of control gauge outfit is because the method for demarcating has at first been adopted in whole measurement, so the accuracy and the power supply of indication, it doesn't matter for the error of electronic component, only relevant with the stability of instrument power supply power supply, as long as power source performance is stable, the indication of instrument is always stable, has so just realized the pin-point accuracy of instrument.Select precision 1% thermistor (temperature) sensor for use, be easy to reach the high temperature measurement more than 200 ℃,, can make circuit realize the pointer temperature survey of pin-point accuracy and high temperature, be fit to the environment for use of automobile by the reasonable establishment of software and hardware circuit.When accuracy requirement is not high, also can cancel EEPROM electric erasable storage chip, adopt default parameter, select precision 1% thermistor (temperature) sensor for use, the precision of total system also can be controlled in 5%.Utilize present technique can also develop other automobile instruments at an easy rate, react the automobile instrument of physics quantitative changeization as oil manometer, vehicle fuel table, water-thermometer etc. by measure analog voltage.

The utility model step motor type thermometer circuit considers that the automobile surge voltage is unfavorable to the work of instrument, added surge absorbing circuit (TVS manages D2), considered the current drain of whole instrument when designing simultaneously, the fluctuation range of voltage (the 16V-36V scope is a design object), keeping 5V three-terminal voltage-stabilizing power input voltage difference scope is 6.5V--26V, choose reasonable regulating resistor R1, the parameter of R2, three terminal regulator and resistive element had both been generated heat rationally, can keep 5V three-terminal voltage-stabilizing power input voltage difference scope again between 6.5V--26V, make the output of power supply keep stable 5V, thereby make the stable operating voltage of instrument, allow that the automobile supply voltage fluctuates in very wide scope, allowable voltage is worked in the scope of 36V at 16V, does not influence the accuracy of instrument.The power-supply fluctuation that meets regulation 24V automobile electric appliance system in the national standard simultaneously is the scope of 22V to 30V.

The utlity model has the indication at night and do not have the sensor warning function, night illumination and lampet interlock, when lampet was bright, instrument night illumination function was effective; It is that magnitude of voltage analysis by survey sensor obtains that no sensor is reported to the police.When sensor broken string or shorted to earth, can send simultaneously audio alert (" temperature sensor broken string, shorted to earth " voice signal or buzzer) and needle deflection warning (pointer is in the continuous deflection in certain position of instrument), the prompting human pilot, in case connect sensor, reporting to the police disappears immediately.

The utility model step motor type thermometer adopts the moving magnetic filed in the stepper motor replacement patent 03241068.9, and the work of stepper motor is not subjected to the influence of environment factors such as temperature, vibration, functional reliability height; The employing thermistor has replaced the thermal resistance in the patent 03241068.9, when though the thermistor of negative temperature coefficient surpasses more than 120 ℃ in temperature, changes in resistance reduced before 120 ℃ during 1 ℃ of temperature variation, but the resistance variations when changing 1 ℃ than resistance and temperature is much bigger (in the time of 200 ℃ also greatly more than 10 times, relevant with the selection of thermistor), can on automobile, realize the single line sensor function, and in actual use, carry out sensor one end bonding on the spot, thermometer is worked highly stable under the car electrics environment, realize the single line sensing, met the request for utilization of automobile more; Because patent 03241068.9 will be used the deflection of duty cycle adjustment moving magnetic filed, maximum operating currenbt is bigger 40 milliamperes than stepper motor instrument, add that the duty cycle adjustment interference is big, to the bridge circuit serious interference, thereby to realize wide operating voltage, and needing to adopt two level power supplies, the utility model only need be used the one-level stabilized power source, directly 24V or the 12V with automobile is depressured to 5V, and functional reliability is higher.

Need to prove: to those of ordinary skill in the art, can also make some changes or distortion to the utility model under the prerequisite that does not change the utility model principle, this belongs to protection domain of the present utility model equally.

Claims

1, step motor type thermometer, it comprises instrument mask (1), index dial (2), circuit board (3), all-night circuit (4), shell (5), it is characterized in that described circuit board (3) comprises the temperature survey loop that thermistor temperature sensor, treatment circuit, stabilized voltage supply, one-chip computer, stepper motor and pointer are formed; Thermistor temperature sensor, treatment circuit, one-chip computer, stepper motor are electrically connected successively, stabilized voltage supply is electrically connected with treatment circuit, one-chip computer by the output branch road, one-chip computer is electrically connected with stepper motor, and treatment circuit is connected with one-chip computer.

2, step motor type thermometer according to claim 1, it is characterized in that also having an EEPROM electricity erasable memorizer in the temperature survey loop of described circuit board (3), described EEPROM electricity erasable memorizer is electrically connected with output branch road, the treatment circuit of stabilized voltage supply, and the EEPROM electricity erasable memorizer is electrically connected with one-chip computer.

3, step motor type thermometer according to claim 1 and 2 is characterized in that described one-chip computer has the interface that connects calibration system and/or audio alert.

4, step motor type thermometer according to claim 1 and 2 is characterized in that the interface that described one-chip computer has and the demarcation PC is connected.

5, step motor type thermometer according to claim 1 and 2 is characterized in that described circuit board (3) is two layers, and last layer circuit board and the circuit board are electrically connected by conductive pole (6) and lead (7).

6, step motor type thermometer according to claim 5, it is characterized in that described stepper motor (8) passes axle (9) and uses self-tapping screw 10 to be connected with index dial (2), index dial (2) is positioned on the layer circuit board, night light (10) is positioned on the lower circuit plate or directly in index dial (2), the input of power supply, temperature sensor, night illumination power supply also connects by conductive pole.

7, step motor type thermometer according to claim 6 is characterized in that described instrument mask (1) and shell (5) are fixing by clamp (11).