Passive dual-electrode liquid level sensor signal detection circuit for automobile cooling liquid

Abstract

The utility model discloses a passive dual-electrode liquid level sensor signal detection circuit for automobile cooling liquid, which comprises a PWM (Pulse Width Modulation) signal controller circuit for receiving a PWM signal provided by an external singlechip and feeding back the PWM signal to a liquid level sensor input signal processing circuit; the liquid level sensor input signal processing circuit is used for transmitting a voltage value fed back by the liquid level sensor to the comparator circuit; the liquid level sensor is a passive dual-electrode liquid level sensor and is used for detecting the liquid level state of automobile cooling liquid; the voltage reference circuit is used for providing a reference value for the comparator circuit; the comparator circuit is used for comparing the voltage value fed back by the liquid level sensor with the reference value provided by the voltage reference circuit, outputting a signal and feeding back the signal to an external single chip microcomputer, so that the liquid level state of the automobile cooling liquid is judged; according to the utility model, a stable signal is output by comparing a liquid level acquisition signal with a reference voltage, the liquid level state of the automobile cooling liquid is detected in real time, and stable technical parameters are provided.

Description

Technical Field

[0001] The utility model relates to the technical field of automotive controllers, and particularly relates to a signal detection circuit for a passive double-electrode liquid level sensor for automotive coolant. Background Art

[0002] With the rapid development of new energy electric vehicles, most of the liquid levels in traditional fuel vehicles originally used liquid level switches to detect whether the coolant was lacking. The detection was relatively simple and could not detect the specific position of the liquid level. At the same time, as the domestic automotive industry goes global, Chinese automotive technology also has to go global, and it will face sensors of both domestic and foreign brands. Basic liquid level sensors often use foreign brands, which have relatively high requirements for hardware circuits and software acquisition. Summary of the Utility Model

[0003] Technical Objective: Aiming at the deficiencies in the understanding and detection technology of foreign liquid level sensors, the utility model discloses a signal detection circuit for a passive double-electrode liquid level sensor for automotive coolant, which solves problems such as weak output signals of the sensor and difficulty in acquisition by the single-chip microcomputer. At the same time, it provides a detection circuit applicable to liquid level sensors of the same type at home and abroad.

[0004] Technical Solution: To achieve the above technical objective, the utility model adopts the following technical solution:

[0005] A signal detection circuit for a passive double-electrode liquid level sensor for automotive coolant includes:

[0006] A PWM signal controller circuit, connected to the liquid level sensor input signal processing circuit, for receiving the PWM signal provided by the external single-chip microcomputer and feeding it back to the liquid level sensor input signal processing circuit;

[0007] A liquid level sensor input signal processing circuit, connected to the liquid level sensor, the PWM signal controller circuit and the comparator circuit, for transmitting the voltage value fed back by the liquid level sensor to the comparator circuit; the liquid level sensor is a passive double-electrode liquid level sensor for detecting the liquid level state of automotive coolant;

[0008] A voltage reference circuit, connected to the comparator circuit, for providing a reference value for the comparator circuit;

[0009] A comparator circuit, connected to the voltage reference circuit and the liquid level sensor input signal processing circuit, for comparing the voltage value fed back by the liquid level sensor with the reference value provided by the voltage reference circuit, and feeding back the output signal to the external single-chip microcomputer to realize the judgment of the liquid level state of automotive coolant.

[0010] Preferably, the PWM signal controller circuit includes a first triode Q1 and a second triode Q2; the base of the second triode Q2 is connected to one end of a resistor R5, and the other end of the resistor R5 is the input terminal TP0 of the PWM signal controller circuit for receiving the PWM signal provided by an external single-chip microcomputer. The emitter of the second triode Q2 is grounded, and the collector of the second triode Q2 is connected to the base of the first triode Q1 through a resistor R4; the emitter of the first triode Q1 is connected to a 5V power supply voltage. The emitter of the first triode Q1 is respectively connected to the base of the first triode Q1 through a resistor R1 and a capacitor C1. The collector of the first triode Q1 is grounded through a resistor R2, and the collector of the first triode Q1 is connected to one end of a resistor R3, and the other end of the resistor R3 serves as the output terminal of the PWM signal controller circuit.

[0011] Preferably, the second triode Q2 is an NPN-type triode, and the first triode Q1 is a PNP-type triode; the model of the first triode Q1 is 2SB1188BCQ, and the model of the second triode Q2 is 2SD1766DBQ.

[0012] Preferably, the liquid level sensor input signal processing circuit includes a capacitor C3, a capacitor C4, a capacitor C5 and a resistor R8; one end of the capacitor C3 serves as the input terminal TP1 of the liquid level sensor input signal processing circuit for connecting one electrode node A of the liquid level sensor. The other end of the capacitor C3 is connected to the output terminal of the PWM signal controller circuit and one end of the resistor R8. The other end of the resistor R8 serves as the output terminal TP3 of the liquid level sensor input signal processing circuit for transmitting the voltage value fed back by the liquid level sensor; one end of the capacitor C5 serves as the input terminal TP2 of the liquid level sensor input signal processing circuit for connecting the other electrode node B of the liquid level sensor. The other end of the capacitor C5 is grounded, and the other end of the capacitor C5 is connected to the output terminal of the liquid level sensor input signal processing circuit through a capacitor C4.

[0013] Preferably, the voltage reference circuit includes two series-connected resistors R10 and R11. One end of the resistor R10 serves as the first input terminal of the voltage reference circuit for connecting a 5V power supply voltage. The other end of the resistor R10 is connected to one end of the resistor R11. The other end of the resistor R11 serves as the second input terminal of the voltage reference circuit for grounding; the midpoint of the series-connected resistors R10 and R11 serves as the output terminal of the voltage reference circuit.

[0014] Preferably, the comparator circuit includes a comparator chip U1A, a resistor R7, and a capacitor C2. Pin 2 of the comparator chip U1A serves as the negative input terminal and is connected to the output terminal of the liquid level sensor input signal processing circuit. Pin 3 of the comparator chip U1A serves as the positive input terminal and is connected to the output terminal of the voltage reference circuit. Pin 4 of the comparator chip U1A is grounded. Pin 1 of the comparator chip U1A is connected to pin 8 of the comparator chip U1A through the resistor R7. Pin 8 of the comparator chip U1A is grounded through the capacitor C2. Pin 1 of the comparator chip U1A serves as the output terminal TP4 of the comparator circuit, outputs the OUT-C signal, and feeds it back to the external microcontroller.

[0015] Preferably, the model of the comparator U1A is LM2903.

[0016] Beneficial effects: The present utility model compares the collected signal of the liquid level with the reference voltage to output a stable signal, real-time detects the liquid level state of the automotive coolant, provides stable technical parameters for the passenger compartment and battery cooling and heating, and ensures the safe operation of the automotive battery and the comfort of the passenger compartment. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0018] Figure 1 It is a schematic structural diagram of a signal detection circuit for a passive dual-electrode liquid level sensor for automotive coolant of the present utility model. Detailed Embodiments

[0019] The following will more clearly and completely illustrate the present utility model by way of a preferred embodiment in conjunction with the drawings, but the present utility model is not limited to the scope of the described embodiments.

[0020] As Figure 1 shown, a signal detection circuit for a passive dual-electrode liquid level sensor for automotive coolant includes:

[0021] A PWM signal controller circuit, connected to the liquid level sensor input signal processing circuit, for receiving the PWM signal provided by the external microcontroller and feeding it back to the liquid level sensor input signal processing circuit;

[0022] A liquid level sensor input signal processing circuit, connected to the liquid level sensor, the PWM signal controller circuit, and the comparator circuit, for transmitting the voltage value fed back by the liquid level sensor to the comparator circuit; the liquid level sensor is a passive dual-electrode liquid level sensor for detecting the liquid level state of the automotive coolant;

[0023] A voltage reference circuit, connected to the comparator circuit, for providing a reference value to the comparator circuit;

[0024] A comparator circuit, connected to the voltage reference circuit and the liquid level sensor input signal processing circuit, for comparing the voltage value fed back by the liquid level sensor with the reference value provided by the voltage reference circuit, and feeding the output signal back to the external single-chip microcomputer to realize the judgment of the liquid level state of the automotive coolant.

[0025] In a specific embodiment, the PWM signal controller circuit includes a first triode Q1 and a second triode Q2. The second triode Q2 is an NPN-type triode, and the first triode Q1 is a PNP-type triode; the model of the first triode Q1 is 2SB1188BCQ, and the model of the second triode Q2 is 2SD1766DBQ.

[0026] Among them, the base of the second triode Q2 is connected to one end of the resistor R5. The other end of the resistor R5 is the input terminal TP0 of the PWM signal controller circuit, for receiving the PWM signal provided by the external single-chip microcomputer. The input terminal TP0 of the PWM signal controller circuit is also the input terminal of a passive double-electrode liquid level sensor signal detection circuit for automotive coolant of the present invention; the emitter of the second triode Q2 is grounded, and the collector of the second triode Q2 is connected to the base of the first triode Q1 through the resistor R4; the emitter of the first triode Q1 is connected to the 5V power supply voltage. The emitter of the first triode Q1 is respectively connected to the base of the first triode Q1 through the resistor R1 and the capacitor C1. The collector of the first triode Q1 is grounded through the resistor R2, and the collector of the first triode Q1 is connected to one end of the resistor R3. The other end of the resistor R3 serves as the output terminal of the PWM signal controller circuit.

[0027] In a specific embodiment, the liquid level sensor input signal processing circuit includes a capacitor C3, a capacitor C4, a capacitor C5 and a resistor R8; one end of the capacitor C3 is the input terminal TP1 of the liquid level sensor input signal processing circuit, for connecting one electrode node A of the liquid level sensor. The other end of the capacitor C3 is connected to the output terminal of the PWM signal controller circuit and one end of the resistor R8. The other end of the resistor R8 is the output terminal TP3 of the liquid level sensor input signal processing circuit, for transmitting the voltage value fed back by the liquid level sensor; one end of the capacitor C5 is the input terminal TP2 of the liquid level sensor input signal processing circuit, for connecting the other electrode node B of the liquid level sensor. The other end of the capacitor C5 is grounded, and the other end of the capacitor C5 is connected to the output terminal of the liquid level sensor input signal processing circuit through the capacitor C4;

[0028] In a specific embodiment, the voltage reference circuit includes two series resistors R10 and R11. One end of resistor R10 serves as the first input terminal of the voltage reference circuit and is used to connect to the 5V power supply voltage. The other end of resistor R10 is connected to one end of resistor R11. The other end of resistor R11 serves as the second input terminal of the voltage reference circuit and is used to ground. The midpoint of the series resistors R10 and R11 serves as the output terminal of the voltage reference circuit, and the generated reference value is the threshold for whether the liquid level is short.

[0029] In a specific embodiment, the comparator circuit includes a comparator chip U1A, a resistor R7, and a capacitor C2. The model of comparator U1A is LM2903.

[0030] Among them, pin 2 of comparator chip U1A serves as the negative input terminal and is connected to the output terminal of the liquid level sensor input signal processing circuit. Pin 3 of comparator chip U1A serves as the positive input terminal and is connected to the output terminal of the voltage reference circuit. Pin 4 of comparator chip U1A is grounded. Pin 1 of comparator chip U1A is connected to pin 8 of comparator chip U1A through resistor R7. Pin 8 of comparator chip U1A is connected to the 5V power supply voltage. Pin 8 of comparator chip U1A is grounded through capacitor C2. Pin 1 of comparator chip U1A serves as the output terminal TP4 of the comparator circuit, outputs the OUT-C signal, and feeds it back to the external microcontroller. The output terminal TP4 of the comparator circuit is also the output terminal of a passive double-electrode liquid level sensor signal detection circuit for automotive coolant of the present invention.

[0031] The positive input terminal of comparator chip U1A inputs the reference value provided by the voltage reference circuit. The reference value is the threshold for whether the liquid level is short. The negative input terminal inputs the voltage value fed back by the liquid level sensor. The reference value and the voltage value fed back by the liquid level sensor are compared to output a signal that is convenient for the microcontroller to detect, and to judge the liquid level state, that is, to judge whether the liquid level of the liquid level sensor is short.

[0032] The working principle of the circuit of this utility model is as follows: First, the PWM signal controller circuit inputs a square wave of 10HZ from the PWM port of the external single-chip microcomputer, with a high level of 2MS and a low level of 98MS. It is input through the base of the second triode Q2, and the collector outputs a reverse PWM signal. Then, it is input through the base of the first triode Q1 to control the collector to output a reverse PWM signal. Finally, the PWM signal output from the collector of the first triode Q1 and the signal input by the external single-chip microcomputer are in-phase signals, which are more stable than the signal directly input by the external single-chip microcomputer to the negative terminal of the comparator U1A. The PWM signal output from the collector of the first triode Q1 passes through the liquid level sensor input signal processing circuit. The PWM signal passes through the capacitor C3 and then through the liquid level sensor electrode A point with the coolant as the conductive medium. Electrons flow from the liquid level sensor electrode A to the electrode B, charging the capacitor C5 connected to the liquid level sensor electrode B. The higher the liquid level, the lower the voltage value at the TP3 point of the voltage feedback output through the capacitor C3 and the resistor R8. When the negative terminal of the comparator U1A is lower than the reference voltage value of the positive terminal of the comparator U1A, the output terminal TP4 point of the comparator U1A is at a high level of 5V; the lower the liquid level, the higher the voltage at the TP3 point of the voltage feedback output through the capacitor C3 and the resistor R8. When the negative terminal of the comparator U1A is higher than the reference voltage of the positive terminal of the comparator U1A, the output terminal TP4 point of the comparator U1A is a PWM signal. In this way, the external single-chip microcomputer detects the PWM signal at the TP4 point to determine the position of the liquid level.

[0033] This utility model compares the collected signal of the liquid level with the reference voltage to output a stable signal, and real-time detects the liquid level state of the automotive coolant, providing stable technical parameters for the passenger compartment and battery cooling and heating, ensuring the safe operation of the automotive battery and the comfort of the passenger compartment. For the working states of foreign passive double-electrode liquid level sensors and other similar liquid level sensors, the circuit of this utility model can stably output and is convenient for the single-chip microcomputer to detect, ensuring the reliable detection of the automotive coolant liquid level. At the same time, the output signal is more conducive to software personnel to write software.

[0034] The above is only the preferred embodiment of this utility model. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of this utility model, several improvements and retouches can still be made, and these improvements and retouches should also be regarded as the protection scope of this utility model.

Claims

1. A passive two-electrode liquid level sensor signal detection circuit for automotive coolant, characterized in that: include: The PWM signal controller circuit is connected to the liquid level sensor input signal processing circuit, and is used to receive the PWM signal provided by the external single chip microcomputer and feed it back to the liquid level sensor input signal processing circuit; The liquid level sensor input signal processing circuit is connected with the liquid level sensor, the PWM signal controller circuit and the comparator circuit, and is used to transmit the voltage value fed back by the liquid level sensor to the comparator circuit; the liquid level sensor is a passive two-electrode liquid level sensor, and is used to detect the liquid level state of the automobile coolant; A voltage reference circuit is connected to the comparator circuit and is used to provide a reference value for the comparator circuit; The comparator circuit is connected to the voltage reference circuit and the liquid level sensor input signal processing circuit, and is used to compare the voltage value fed back by the liquid level sensor with the reference value provided by the voltage reference circuit, and the output signal is fed back to the external single-chip microcomputer to realize the liquid level status judgment of the automobile coolant.

2. A passive two-electrode liquid level sensor signal detection circuit for automobile coolant according to claim 1, characterized in that: The PWM signal controller circuit includes a first transistor Q1 and a second transistor Q2; the base of the second transistor Q2 is connected to one end of a resistor R5, the other end of the resistor R5 is an input end TP0 of the PWM signal controller circuit, and is used to receive a PWM signal provided by an external single-chip microcomputer; the emitter of the second transistor Q2 is grounded, and the collector of the second transistor Q2 is connected to the base of the first transistor Q1 through a resistor R4; the emitter of the first transistor Q1 is connected to a 5V power supply voltage, the emitter of the first transistor Q1 is connected to the base of the first transistor Q1 through a resistor R1 and a capacitor C1, respectively, the collector of the first transistor Q1 is grounded through a resistor R2, the collector of the first transistor Q1 is connected to one end of a resistor R3, and the other end of the resistor R3 serves as an output end of the PWM signal controller circuit.

3. A passive two-electrode liquid level sensor signal detection circuit for automobile coolant according to claim 2, characterized in that: The second transistor Q2 is an NPN transistor, and the first transistor Q1 is a PNP transistor; the model of the first transistor Q1 is 2SB1188BCQ, and the model of the second transistor Q2 is 2SD1766DBQ.

4. A passive two-electrode liquid level sensor signal detection circuit for automobile coolant according to claim 1, characterized in that: The liquid level sensor input signal processing circuit includes capacitor C3, capacitor C4, capacitor C5 and resistor R8; one end of capacitor C3 serves as input end TP1 of the liquid level sensor input signal processing circuit, and is used to connect one of the electrode nodes A of the liquid level sensor; the other end of capacitor C3 is connected to the output end of the PWM signal controller circuit and one end of resistor R8; the other end of resistor R8 serves as output end TP3 of the liquid level sensor input signal processing circuit, and is used to transmit the voltage value fed back by the liquid level sensor; one end of capacitor C5 serves as input end TP2 of the liquid level sensor input signal processing circuit, and is used to connect another electrode node B of the liquid level sensor; the other end of capacitor C5 is grounded; the other end of capacitor C5 is connected to the output end of the liquid level sensor input signal processing circuit through capacitor C4.

5. A passive two-electrode liquid level sensor signal detection circuit for automobile coolant according to claim 1, characterized in that: The voltage reference circuit includes two resistors R10 and R11 connected in series, one end of the resistor R10 serves as the first input end of the voltage reference circuit, and is used to connect to a 5V power supply voltage, the other end of the resistor R10 is connected to one end of the resistor R11, and the other end of the resistor R11 serves as the second input end of the voltage reference circuit, and is used to be grounded; the midpoint of the series-connected resistors R10 and R11 serves as the output end of the voltage reference circuit.

6. A passive two-electrode liquid level sensor signal detection circuit for automotive coolant according to claim 1, characterized in that: The comparator circuit includes a comparator chip U1A, a resistor R7 and a capacitor C2. Pin 2 of the comparator chip U1A serves as a negative input terminal and is connected to the output terminal of the liquid level sensor input signal processing circuit. Pin 3 of the comparator chip U1A serves as a positive input terminal and is connected to the output terminal of the voltage reference circuit. Pin 4 of the comparator chip U1A is grounded. Pin 1 of the comparator chip U1A is connected to pin 8 of the comparator chip U1A through resistor R7, and pin 8 of the comparator chip U1A is grounded through capacitor C2. Pin 1 of the comparator chip U1A serves as the output terminal TP4 of the comparator circuit, outputs an OUT-C signal, and feeds back to an external microcontroller.

7. A passive two-electrode liquid level sensor signal detection circuit for automobile coolant according to claim 6, characterized in that: The model of the comparator chip U1A is LM2903.

Images