CN204330174U - Fluid temperature detection system - Google Patents

Abstract

The utility model provides a liquid temperature detection system, wherein the detection system includes: a transmitting circuit for emitting light, a receiving circuit for receiving reflected light and converting it into a first electrical signal, and a receiving circuit for transmitting the first electrical signal The signal is filtered and amplified, an electric signal processing circuit for obtaining a second electric signal, and a microprocessor for identifying effective signals in the second electric signal and judging the temperature of the liquid. The transmitting circuit is connected with the microprocessor, and the receiving circuit, the electric signal processing circuit and the microprocessor are connected in sequence. Utilizing the principle that the liquid surface will produce foam or fluctuations with temperature changes, the judgment of whether the liquid temperature reaches the target temperature is realized by detecting the reflected light irradiated on the liquid surface, and the detection of the liquid is realized without the sensor needing to contact the liquid to be measured. The temperature control effectively adapts to the requirements of some special occasions and reduces the manufacturing cost.

Description

Liquid temperature detection system

technical field

The utility model relates to the field of temperature detection, in particular to a liquid temperature detection system.

Background technique

In existing liquid heaters, it is basically necessary to use a temperature signal as a control signal to realize the control of the liquid heating temperature. The general temperature signal acquisition method requires that the sensor must be in contact with the liquid or use the liquid surface signal as the signal input for temperature control. The sensor needs to be in contact with the liquid to be measured. manufacturing cost.

Therefore, the prior art has yet to be developed.

Utility model content

In view of the shortcomings of the above-mentioned prior art, the purpose of this utility model is to provide a liquid temperature detection system, aiming at solving the problem in the prior art that obtaining a liquid temperature signal requires the sensor to be in contact with the liquid to be measured.

In order to achieve the above object, the utility model has taken the following technical solutions:

A liquid temperature detection system, which includes: a transmitting circuit for emitting light, a receiving circuit for receiving reflected light and converting it into a first electrical signal, and filtering and amplifying the first electrical signal to obtain An electrical signal processing circuit for the second electrical signal, and a microprocessor for identifying effective signals in the second electrical signal and judging the liquid temperature; the transmitting circuit is connected to the microprocessor, and the receiving circuit passes the electrical signal The processing circuit is connected to the microprocessor.

In the liquid temperature detection system, the transmitting circuit specifically includes a first triode, a second triode, a first capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor , a polar capacitor, a Zener diode and several light-emitting diodes connected in parallel, the emitter of the first triode is connected to the power supply, the base of the first triode is connected to the power supply through the first resistor, and connected to the power supply through the second resistor The collector of the second triode is connected, the base of the second triode is connected with the microprocessor and one end of the fourth resistor through the third resistor, and the other end of the fourth resistor is connected to the emitter of the second triode. pole is grounded, the collector of the first triode is connected to the negative pole of the Zener diode, the positive pole of the LED, the positive pole of the polar capacitor and one end of the first capacitor through the fifth resistor, the negative pole of the Zener diode, the negative pole of the LED, Both the negative pole of the polarized capacitor and the other end of the first capacitor are grounded.

In the liquid temperature detection system, the receiving circuit includes a third transistor, a fourth transistor, a second capacitor, a third capacitor, a second Zener diode, a phototransistor, a sixth resistor, and a seventh resistor , the eighth resistor, the ninth resistor, the tenth resistor and the eleventh resistor, the emitter of the third triode is connected to the power supply, the base of the third triode is connected to the power supply through the sixth resistor, and also through the seventh The resistor is connected to the collector of the fourth transistor, and the collector of the third transistor is connected to one end of the second capacitor, one end of the third capacitor, the negative pole of the Zener diode, and the collector of the phototransistor through the eighth resistor. The base of the fourth transistor is connected to one end of the ninth resistor, the other end of the ninth resistor is connected to the microprocessor, and grounded through the tenth resistor, the emitter of the fourth transistor, the other end of the second capacitor One end, the other end of the third capacitor and the negative pole of the Zener diode are all grounded, the emitter of the phototransistor is grounded through the eleventh resistor, and the collector and emitter of the phototransistor are also connected to the electrical signal processing circuit.

In the liquid temperature detection system, the third transistor is a PNP transistor, and the fourth transistor is an NPN transistor.

In the liquid temperature detection system, the electrical signal processing circuit includes a first filter amplifier unit and a second filter amplifier unit; the first filter amplifier unit specifically includes: a fourth capacitor, a fifth capacitor, a sixth capacitor, The seventh capacitor, the eighth capacitor, the first operational amplifier, the twelfth resistor, the thirteenth resistor, the fourteenth resistor, the fifteenth resistor, the sixteenth resistor, the seventeenth resistor, the eighteenth resistor, the tenth Nine resistors, one end of the fourth capacitor is connected to the emitter of the phototransistor, and one end of the fourteenth resistor and one end of the fifth capacitor are connected through the thirteenth resistor, and the other end of the fourteenth resistor is connected through the seventh capacitor Connect one end of the fifteenth resistor to one end of the sixteenth resistor, the other end of the fourth capacitor, the other end of the fifth capacitor, and the other end of the sixteenth resistor are all grounded, and the other end of the fifteenth resistor is connected to the The noninverting input terminal of an operational amplifier is also connected to the collector of the phototransistor through the twelfth resistor, and grounded through the sixth capacitor, and the inverting input terminal of the first operational amplifier is connected to one end of the eighteenth resistor through the seventeenth resistor, The other end of the eighteenth resistor is connected to the output end of the first operational amplifier, the output end of the first operational amplifier is connected to one end of the nineteenth resistor and the second filter amplifying unit through the eighth capacitor, and the other end of the nineteenth resistor is grounded.

In the liquid temperature detection system, the second filtering and amplifying unit specifically includes: a ninth capacitor, a tenth capacitor, a second operational amplifier, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, a Twenty-three resistors, twenty-fourth resistors, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier through the twentieth resistor and the eighth capacitor in turn, and the inverting input terminal of the second operational amplifier is passed through The twenty-first resistance is grounded, and is also connected to the output end of the second operational amplifier through the twenty-second resistance, the output end of the second operational amplifier is connected to one end of the twenty-third resistance, and the other end of the twenty-third resistance One end is connected to the microprocessor, the twenty-fourth resistor is also passed through, and the tenth capacitor is grounded.

In the liquid temperature detection system, the PB3 end of the microprocessor is connected to the other end of the twenty-third resistor, the PB2 end of the microprocessor is connected to the other end of the ninth resistor, and the PA2/AN2 end of the microprocessor passes through the third The resistor is connected to the base of the second triode, and the PA7 end of the microprocessor is connected to the actuator.

In the liquid temperature detection system, the actuator includes a diode, a relay, a battery, a fifth triode, a twenty-fifth resistor and a heating wire, and the base of the fifth triode passes through the twenty-fifth The resistor is connected to the PA7 terminal of the microprocessor, the collector of the fifth triode is connected to the power supply through the coil of the relay, the emitter of the fifth triode is grounded, the cathode of the diode is connected to the power supply, and the anode of the diode is connected to the fifth triode The collector of the tube, one end of the normally open contact of the relay is connected to the positive pole of the battery, and the other end of the normally open contact of the relay is connected to the negative pole of the battery through the heating wire.

Beneficial effects: the liquid temperature detection system provided by the utility model utilizes the principle that the liquid surface will produce foam or fluctuations with temperature changes, and realizes the judgment of whether the liquid temperature reaches the target temperature by detecting the reflected light irradiated on the liquid surface. The temperature control of the liquid is realized without contacting the liquid to be measured, which effectively meets the requirements of some special occasions and reduces the manufacturing cost.

Description of drawings

Fig. 1 is a structural block diagram of a liquid temperature detection system in a specific embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of the transmitting circuit of the liquid temperature detection system in a specific embodiment of the present invention.

Fig. 3 is a schematic circuit diagram of a receiving circuit of a liquid temperature detection system in a specific embodiment of the present invention.

Fig. 4 is a schematic circuit diagram of the first filtering and amplifying unit of the liquid temperature detection system in a specific embodiment of the present invention.

Fig. 5 is a schematic circuit diagram of the second filtering and amplifying unit of the liquid temperature detection system in a specific embodiment of the present invention.

Fig. 6 is a schematic circuit diagram of the microprocessor and the actuator of the liquid temperature detection system in the specific embodiment of the present invention.

Fig. 7 is a schematic circuit diagram of the power supply of the liquid temperature detection system in a specific embodiment of the present invention.

Fig. 8 is a flow chart of the liquid temperature detection method in a specific embodiment of the present invention.

Detailed ways

The utility model provides a liquid temperature detection system. In order to make the purpose, technical solution and effect of the utility model more clear and definite, the utility model will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

As shown in Figure 1, the specific embodiment of the liquid temperature detection system of the present invention. The detection system includes: a transmitting circuit 100 for emitting light, a receiving circuit 200 for receiving reflected light and converting it into a first electrical signal, and filtering and amplifying the first electrical signal to obtain a second electrical signal. An electrical signal processing circuit 300 for the electrical signal, and a microprocessor 400 for identifying valid signals in the second electrical signal and judging the temperature of the liquid. The system may also include an actuator 500 that executes certain operations, such as stopping heating, when it is judged that the temperature of the liquid reaches a certain value.

The transmitting circuit is connected to the microprocessor, and the receiving circuit, the electrical signal processing circuit, the microprocessor, and the actuator 500 are connected in sequence.

The specific working principle of the detection system is as follows: some liquids with high surface tension, such as coffee, milk, and pasta, will generate a large amount of foam or bubbles when the temperature rises or boils, and strong vaporization occurs. And when these liquids are at relatively low temperature, if there is no external shaking, etc., the liquid surface is a relatively calm and still plane. Therefore, there is a certain correlation between the temperature of the liquid and the calmness of the liquid surface, which can be used as the basis for qualitative detection.

The transmitting circuit 100 emits light, which strikes the liquid surface of the liquid to be measured at a certain angle, and the receiving circuit 200 receives the reflected light of the liquid surface and converts it into an electrical signal. As mentioned above, when the liquid surface is a plane in a static state, the reflected light and the liquid surface have a strong surge, and the reflected light when a large amount of foam is generated has significantly different light characteristics. (It can be considered to be equivalent to the displacement movement of the surface of the bubble relative to the sensor)

The conversion function for converting the reflected light into an electrical signal can be simply expressed by the following function:

V= K1*E0+K2*E(ω)

Among them, V is the voltage after the optical signal is converted into an electrical signal, K1 and K2 are the photoelectric conversion constants (determined by the specific circuit settings), E0 is the voltage from static reflection to photoelectric conversion, E is the dynamic component of photoelectric conversion, and ω is the reflection The angular velocity at which the light moves relative to the sensor.

After the processing module 300 performs certain processing on the electrical signal, such as filtering or amplifying processing, the electrical signal is output to the microprocessor 400, and the microprocessor recognizes the effective signal in the electrical signal and judges whether it reaches the preset designation. Value, to judge the surging situation of the liquid surface, and then judge whether the temperature of the liquid reaches the preset situation, such as boiling.

The preset specified value can be determined through multiple pre-tests, such as pre-testing the electrical signal characteristics of the same liquid boiling state. The specific test method is the prior art and will not be repeated.

After the microprocessor 400 judges that the electrical signal reaches a preset specified value, it can output an execution command to control the actuator 500 to perform certain operations, and the relevant functions of the liquid heating device have been completed. Specifically, as shown in FIG. 1 , the actuator may further include an output unit 600 . When the temperature reaches the target temperature, the microprocessor outputs a control signal, and after receiving the signal, the output unit 600 controls the actuator 500 to perform a preset action (such as stopping heating). The output unit 600 can be a relay, or other power devices such as thyristor, etc., and the actuator 500 can be a heating wire switch, or a motor, solenoid valve, electromagnet and other similar devices.

Of course, the system can also use a power supply, and the power supply can adopt any suitable type of direct current, alternating current power and the like.

Preferably, as shown in FIG. 1 , the microprocessor 400 is connected to the transmitting circuit 100 and the receiving circuit 200 for controlling its start-up and closing states. Extend the service life of components and save power.

In one of the specific embodiments of the present utility model, the above-mentioned transmitting circuit 100 emits light at a fixed frequency F1 to the liquid surface of the liquid to be measured. If the liquid is at a lower temperature and the liquid surface is a horizontal and still plane, the phase of the reflected light after amplification processing will be exactly the same as that of the original frequency F1, and there is no phase difference between the two. When the liquid surface surges or the gas bubbles are generated, due to the instability of the bubbles, the emitted light will fluctuate, and the phase of the reflected light after amplification and the original frequency F1 will be different. The microprocessor 400 can determine whether the phase change of the reflected light has reached a preset level by identifying an effective signal corresponding to the phase of the reflected light in the electrical signal, thereby determining whether the liquid to be tested has reached a preset temperature.

More specifically, the electrical signal processing circuit 200 specifically includes a first filtering and amplifying unit 301 for filtering out frequencies less than 5 Hz and amplifying electrical signals, and a second filtering and amplifying unit for filtering out frequencies greater than 40 Hz and amplifying electrical signals Unit 302.

The receiving circuit, the first filtering and amplifying unit, the second filtering and amplifying unit, and the microprocessor are connected in sequence.

Generally speaking, when the liquid level fluctuates, the frequency of the reflected light is between 5-40 Hz. The above-mentioned first and second filtering and amplifying units can effectively eliminate the light less than about 5 Hz after photoelectric conversion when the liquid level is not surging. signal, and the interference source of the system itself or the interference signal of the external light source. The filtering and amplifying unit amplifies the converted weak electrical signal to an electrical signal that can be recognized and used by the microprocessor 400 through two-stage signal amplification. In another specific embodiment of the present utility model, the effective signal can be one wide pulse longer than 1000 mS or two wide pulses longer than 500 mS or more than 3 wide pulses longer than 100 mS within a period of two seconds. When the microprocessor 400 recognizes the above-mentioned effective signal in the electrical signal, it judges whether the liquid has reached a preset temperature based on it, and controls the actuator 500 to perform specific operations.

It should be noted that, in the specific embodiments of the present invention, it is provided that phase judgment and wide pulse judgment are used to indirectly realize the judgment of the liquid temperature. The system of the present invention can also adopt other ways of using reflected light to detect the state of the liquid level and indirectly detect the temperature of the liquid, such as frequency shift of reflected light.

More specifically, as shown in FIG. 2 , the transmitting circuit specifically includes a first transistor Q1, a second transistor Q2, a first capacitor C1, a first resistor R1, a second resistor R2, and a third resistor R3 , the fourth resistor R4, the fifth resistor R5, the polarity capacitor C`, the first Zener diode ZD1 and several light-emitting diodes D connected in parallel. The emitter of the first transistor Q1 is connected to the 12V power supply, the base of the first transistor Q1 is connected to the 12V power supply through the first resistor R1, and is also connected to the collector of the second transistor Q2 through the second resistor R2 , the base of the second transistor Q2 is connected to the microprocessor 400 and one end of the fourth resistor R4 through the third resistor R3, the other end of the fourth resistor R4 and the emitter of the second transistor Q2 are grounded, The collector of the first triode Q1 is connected to the negative pole of the Zener diode ZD1, the positive pole of the light emitting diode D, the positive pole of the polarity capacitor C and one end of the first capacitor C1 through the fifth resistor R5, the negative pole of the Zener diode ZD1, the light emitting diode The cathode of the diode D, the cathode of the polar capacitor and the other end of the first capacitor C1 are all grounded. The number of the light-emitting diodes can be determined according to actual working conditions, and generally can be set to three. Of course, other light-emitting components can also be used to generate other different types of light sources.

As shown in Figure 3, the receiving circuit specifically includes a third transistor Q3, a fourth transistor Q4, a second capacitor C2, a third capacitor C3, a second Zener diode ZD2, a phototransistor SEN, a sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11. The emitter of the third transistor Q3 is connected to the power supply, the base is connected to the 12V power supply through the sixth resistor R6, and the collector of the fourth transistor Q4 is connected through the seventh resistor R7, and the collector of the third transistor Q3 The electrodes are connected to one end of the second capacitor C2, one end of the third capacitor C3, the cathode of the Zener diode ZD2, and the collector of the phototransistor SEN through the eighth resistor R8, and the base of the fourth transistor Q4 is connected to the ninth One end of the resistor R9 is connected, the other end of the ninth resistor R9 is connected to the microprocessor 400, and grounded through the tenth resistor R10, the emitter of the fourth triode Q4, the other end of the second capacitor C2, and the third capacitor C3 The other end of and the negative electrode of Zener diode ZD2 are both grounded, the emitter of the phototransistor SEN is grounded through the eleventh resistor R11, and the collector and emitter of the phototransistor SEN are also connected to the electrical signal processing circuit 300. In this embodiment, the receiving circuit uses a phototransistor as a photoelectric conversion element, but other types of photosensitive devices can also be used to convert optical signals into electrical signals.

Wherein, the first transistor and the third transistor are PNP transistors, and the second transistor and the fourth transistor are NPN transistors. Of course, in other embodiments, each triode can also be replaced by a corresponding type of switching circuit (such as a MOS transistor or a switching circuit composed of a triode of corresponding polarity and an inverter), which is limited by the present invention.

As shown in FIG. 4, the first filtering and amplifying unit specifically includes: a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a first operational amplifier U01A, a twelfth capacitor Resistor R12, thirteenth resistor R13, fourteenth resistor R14, fifteenth resistor R15, sixteenth resistor R16, seventeenth resistor R17, eighteenth resistor R18, nineteenth resistor R19. One end of the fourth capacitor C4 is connected to the emitter of the phototransistor SEN, and one end of the fourteenth resistor R14 and one end of the fifth capacitor C5 are connected through the thirteenth resistor E13, and the other end of the fourteenth resistor R14 is passed through The seventh capacitor C7 is connected to one end of the fifteenth resistor R15 and one end of the sixteenth resistor R16, the other end of the fourth capacitor C4, the other end of the fifth capacitor C5, and the other end of the sixteenth resistor R16 are all grounded, the The other end of the fifteenth resistor R15 is connected to the non-inverting input terminal of the first operational amplifier U01A, also connected to the collector of the phototransistor SEN through the twelfth resistor R12, and grounded through the sixth capacitor C6, the inverting phase of the first operational amplifier U01A The input end is connected to one end of the eighteenth resistor R18 through the seventeenth resistor R17, the other end of the eighteenth resistor R18 is connected to the output end of the first operational amplifier U01A, and the output end of the first operational amplifier U01A is connected to the first operational amplifier through the eighth capacitor C8. One end of the nineteenth resistor R19 is connected to the second filtering and amplifying unit, and the other end of the nineteenth resistor R19 is grounded. Among them, the seventh capacitor C7 and the sixteenth resistor R16, and the eighth capacitor C8 and the nineteenth resistor R19 form a high-pass filter, which can be used to filter out low-frequency electrical signals below 5 Hz.

As shown in Figure 5, the second filtering and amplifying unit specifically includes: a ninth capacitor C9, a tenth capacitor C10, a second operational amplifier U01B, a nineteenth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, the twenty-third resistor R23, and the twenty-fourth resistor R24. The non-inverting input terminal of the second operational amplifier U01B is sequentially connected to the output terminal of the first operational amplifier U01A through the nineteenth resistor R20 and the eighth capacitor C8, and the inverting input terminal of the second operational amplifier U01B is connected through the twenty-first resistor R21 Grounded, also connected to the output terminal of the second operational amplifier U01B through the twenty-second resistor R22, the output terminal of the second operational amplifier U01B is connected to one end of the twenty-third resistor R23, the other end of the twenty-third resistor R23 One end is connected to the microprocessor 400, and also through the twenty-fourth resistor R24, and the tenth capacitor C10 is grounded. Wherein, the nineteenth resistor R20 and the ninth capacitor C9 and the twenty-third resistor R23 and the tenth capacitor C10 form a low-pass filter, which can be used to filter out high-frequency electrical signals greater than 40 Hz.

Please refer to Figure 1 and Figure 6, the PB3 end of the microprocessor is connected to the other end of the twenty-third resistor R23, the PB2 end of the microprocessor is connected to the other end of the ninth resistor R9, and the PA2/AN2 end of the microprocessor is connected through the third The resistor is connected to the base of the second triode Q2, and the PA7 terminal of the microprocessor is connected to the actuator. After the system is heated for a period of time, the PA2/AN2 terminal of the microprocessor 400 outputs a high level to make the second triode Q2 and the first triode Q1 conduct, so that the anode of the light-emitting diode D is very high, so that The light-emitting diode D continues to emit light. At the same time, the PB2 terminal of the microprocessor 400 outputs a high level to make the fourth triode Q4 and the second triode Q2 conduct, so that the collector of the photosensitive transistor SEN can receive the light emitted by the light emitting diode D. Thereby a voltage signal is generated, and after the voltage signal is subjected to high-pass filtering and amplifying processing by the first filtering and amplifying unit, it enters the second filtering and amplifying unit for low-pass filtering and amplifying processing, and then is sent to the PB3 terminal of the microprocessor 400, and is judged by the microprocessor 400 If the received signal is valid, the actuator will stop working if it is valid, and the actuator will continue to work if it is invalid.

Please continue to refer to FIG. 6, the actuator 600 includes a diode D1, a relay K01, a battery BAT, a fifth triode Q5, a twenty-fifth resistor R25 and a heating wire E1, the base of the fifth triode Q5 Connect the PA7 terminal of the microprocessor through the twenty-fifth resistor R25, the collector of the fifth triode Q5 is connected to the 12V power supply through the coil of the relay K01, the emitter of the fifth triode Q5 is grounded, and the cathode of the diode D1 Connect the 12V power supply, the anode of the diode D1 is connected to the collector of the fifth triode Q5, one end of the normally open contact of the relay K01 is connected to the positive electrode of the battery BAT, and the other end of the normally open contact of the relay K01 is connected to the battery through the heating wire E1 The negative pole of BAT. During normal heating, the PA7 terminal of the microprocessor outputs a high level to turn on the fifth triode Q5, make the relay K01 pull in, and keep heating the heating wire. When the microprocessor judges that the temperature of the liquid reaches the requirement, the PA7 terminal of the microprocessor outputs a low level to cut off the fifth triode Q5, disconnect the relay K01, and stop the heating of the heating wire.

Please refer to 7, the liquid temperature detection system of the present invention also includes a power supply that provides 12V voltage and 5V power supply to the transmitting circuit, receiving circuit, electrical signal processing circuit and microprocessor, which includes a power module U1, a step-down chip U2, a fuse F1, varistor ZNR1, the LIN terminal of the power module U1 is connected to the power plug through the fuse F1, the NIN terminal of the power module U1 is connected to the power plug, and the +12V terminal of the power module U1 is connected to the transmitting circuit, the receiving circuit, the electrical signal processing circuit and the step-down circuit. The Vin terminal of the pressure chip U2, and the Vout terminal of the step-down chip U2 are connected to the VDD terminal of the microprocessor. One end of the varistor ZNR1 is connected to the LIN terminal of the power module U1, and the other end of the varistor ZNR1 is connected to the NIN terminal of the power module U1. When the grid voltage is abnormal, the fuse F1 and the varistor ZNR1 protect the power supply.

In addition, the utility model also provides a method for detecting the liquid temperature by using the detection system. As shown in Figure 6, the method comprises the steps:

S100. The emitting circuit emits light to the liquid surface of the liquid to be measured.

S200. The receiving circuit receives the reflected light reflected by the liquid surface of the liquid to be measured and converts it into a first electrical signal.

S300. After the electrical signal processing module filters and amplifies the first electrical signal, it produces a second electrical signal and outputs it to the microprocessor.

S400. The microprocessor identifies an effective signal in the second electrical signal and determines the temperature of the liquid to be tested.

In summary, the liquid temperature detection system provided by the utility model utilizes the principle that the liquid surface will produce foam or fluctuations with temperature changes, and realizes the judgment of whether the liquid temperature reaches the target temperature by detecting the reflected light irradiated on the liquid surface. The temperature control of the liquid is realized under the condition that the sensor does not need to contact the liquid to be measured, which effectively meets the requirements of some special occasions and reduces the manufacturing cost. Moreover, the above detection system has good versatility, and can also be applied to other control systems as an auxiliary control signal output.

It can be understood that, for those of ordinary skill in the art, equivalent replacements or changes can be made according to the technical solutions of the utility model and the concept of the utility model, and all these changes or replacements should belong to the appended claims of the utility model protected range.

Claims (8)

1. a fluid temperature detection system, it is characterized in that, comprise: for the radiating circuit of emission of light, for receiving reflected light and being converted into the receiving circuit of the first electric signal, for carrying out filtering to described first electric signal and amplifying process, obtain the electric signal processing circuit of the second electric signal, and for identifying useful signal in described second electric signal and judging the microprocessor of fluid temperature; Described radiating circuit is connected with microprocessor, and described receiving circuit connects microprocessor by electric signal processing circuit.

2. fluid temperature detection system according to claim 1, it is characterized in that, described radiating circuit specifically comprises the first triode, second triode, first electric capacity, first resistance, second resistance, 3rd resistance, 4th resistance, 5th resistance, polar capacitor, the light emitting diode of voltage stabilizing diode and several parallel connections, the emitter of the first triode is connected with power supply, the base stage of the first triode is connected with power supply by the first resistance, also be connected with the collector of the second triode by the second resistance, the base stage of described second triode is connected with one end of microprocessor and the 4th resistance by the 3rd resistance, the other end of the 4th resistance and the grounded emitter of the second triode, the collector of the first triode connects the negative pole of voltage stabilizing diode by the 5th resistance, the positive pole of light emitting diode, the positive pole of polar capacitor and one end of the first electric capacity, the negative pole of voltage stabilizing diode, the negative pole of light emitting diode, the negative pole of polar capacitor and the equal ground connection of the other end of the first electric capacity.

3. fluid temperature detection system according to claim 2, is characterized in that, described receiving circuit comprises the 3rd triode, 4th triode, second electric capacity, 3rd electric capacity, second voltage stabilizing diode, phototriode, 6th resistance, 7th resistance, 8th resistance, 9th resistance, tenth resistance and the 11 resistance, the emitter of described 3rd triode connects power supply, the base stage of the 3rd triode connects power supply by the 6th resistance, and also connected the collector of the 4th triode by the 7th resistance, the collector of the 3rd triode connects one end of the second electric capacity by the 8th resistance, one end of 3rd electric capacity, the negative pole of voltage stabilizing diode, and the collector of phototriode, the base stage of described 4th triode is connected with one end of the 9th resistance, and the other end of the 9th resistance is connected with microprocessor, also by the tenth resistance eutral grounding, and the emitter of the 4th triode, the other end of the second electric capacity, the other end of the 3rd electric capacity and the equal ground connection of negative pole of voltage stabilizing diode, the emitter of phototriode is by the 11 resistance eutral grounding, and the collector and emitter of phototriode is also connected with electric signal processing circuit.

4. fluid temperature detection system according to claim 3, is characterized in that, described 3rd triode is PNP triode, and the 4th triode is NPN triode.

5. fluid temperature detection system according to claim 4, is characterized in that, described electric signal processing circuit comprises the first filter and amplification unit and the second filter and amplification unit, described first filter and amplification unit specifically comprises: the 4th electric capacity, 5th electric capacity, 6th electric capacity, 7th electric capacity, 8th electric capacity, first operational amplifier, 12 resistance, 13 resistance, 14 resistance, 15 resistance, 16 resistance, 17 resistance, 18 resistance, 19 resistance, one end of described 4th electric capacity connects the emitter of phototriode, also connect one end of the 14 resistance and one end of the 5th electric capacity by the 13 resistance, the other end of described 14 resistance connects one end of the 15 resistance and one end of the 16 resistance by the 7th electric capacity, the other end of the 4th electric capacity, the other end of the 5th electric capacity, the equal ground connection of the other end of the 16 resistance, the other end of described 15 resistance connects the in-phase input end of the first operational amplifier, also the collector of phototriode is connected by the 12 resistance, also by the 6th capacity earth, the inverting input of the first operational amplifier connects one end of the 18 resistance by the 17 resistance, the other end of the 18 resistance connects the output terminal of the first operational amplifier, the output terminal of the first operational amplifier connects one end and the second filter and amplification unit of the 19 resistance, the other end ground connection of the 19 resistance by the 8th electric capacity.

6. fluid temperature detection system according to claim 5, it is characterized in that, described second filter and amplification unit specifically comprises: the 9th electric capacity, tenth electric capacity, second operational amplifier, 20 resistance, 21 resistance, 22 resistance, 23 resistance, 24 resistance, the in-phase input end of described second operational amplifier is successively by the 20 resistance, 8th electric capacity connects the output terminal of the first operational amplifier, the inverting input of the second operational amplifier is by the 21 resistance eutral grounding, also be connected with the output terminal of the second operational amplifier by the 22 resistance, the output terminal of described second operational amplifier is connected with one end of the 23 resistance, the other end of the 23 resistance is connected with microprocessor, also by the 24 resistance, tenth capacity earth.

7. fluid temperature detection system according to claim 6, it is characterized in that, the PB3 of microprocessor holds the other end of connection the 23 resistance, the PB2 of microprocessor holds the other end of connection the 9th resistance, the PA2/AN2 end of microprocessor connects the base stage of the second triode by the 3rd resistance, the PA7 end of microprocessor connects topworks.

8. fluid temperature detection system according to claim 7, it is characterized in that, described topworks comprises diode, relay, battery, 5th triode, 25 resistance and heating wire, the base stage of described 5th triode connects the PA7 end of microprocessor by the 25 resistance, the collector of the 5th triode connects power supply by the coil of relay, the grounded emitter of the 5th triode, the negative pole of described diode connects power supply, the positive pole of diode connects the collector of the 5th triode, one end of the normally opened contact of relay connects the positive pole of battery, the other end of the normally opened contact of relay connects the negative pole of battery by heating wire.