An electromagnetic valve detection circuit, control circuit and gas detector

Abstract

The utility model provides a kind of solenoid valve detection circuit, control circuit and gas detector, detection control circuit, receive the detection control signal and clock signal of external input to control to solenoid valve apply solenoid valve detection's second supply voltage;Signal acquisition circuit obtains the voltage sampling signal of the negative connection end of solenoid valve;Result comparison circuit compares voltage sampling signal and reference voltage signal, obtains voltage comparison result and outputs.In existing control circuit, integrate effective solenoid valve fault detection function, to find and handle the possible fault in solenoid valve working process in time, ensure the stable operation of system.

Description

Technical Field

[0001] This utility model relates to the field of solenoid valve fault detection and control technology, and in particular to a solenoid valve detection circuit, control circuit and gas detector. Background Technology

[0002] In the current technological field, solenoid valves, as key components for controlling fluid flow, are widely used in various industrial and household appliances. Their operation typically relies on a control circuit connected to a processor to achieve precise control. Specifically, such as... Figure 1 The prior art shown depicts a switching control circuit for a solenoid valve (CN3). This circuit provides a first supply voltage of 12V (VIN1) and includes resistors (R11, R12, R13, R14, R15, R16, R18, R19), voltage regulator capacitors (C1, C2), capacitor (C3), an NPN transistor (TR2), a PNP transistor (TR1), a transistor (Q5), and voltage regulator diodes (ZD1, ZD2). CP1, CP2, CP3, CP4, CP5, and CP6 are merely test points for a series of circuits. The processor manipulates the solenoid valve's operating state by generating a specific switching control signal (VALVE_ON). When the processor issues an on signal (VALVE_ON = 0), the switching control circuit energizes the solenoid valve; conversely, if the processor issues an off signal (VALVE_ON = 1), the NPN transistor (TR2) in the control module conducts, and the solenoid valve is de-energized. Solenoid valves come in two types: normally open and normally closed. For normally open valves, the valve is open when no current flows through the solenoid coil, allowing the medium to flow; when the solenoid coil is energized, the valve closes, preventing the medium from flowing. For normally closed valves, the valve is closed when no current flows through the solenoid coil, preventing the medium from flowing; when the solenoid coil is energized, the valve opens, allowing the medium to flow.

[0003] While this design can meet basic control requirements, it still has certain limitations in practical applications. In particular, existing control circuits lack the ability to detect potential short-circuit and open-circuit faults in solenoid valves. This can not only lead to a decrease in system performance but may even cause the entire system to malfunction or be damaged. For example, if the connection between a household combustible gas detector and the solenoid valve is short-circuited or open-circuited, the gas supply cannot be effectively cut off after a gas leak, leading to serious consequences. Utility Model Content

[0004] To improve the reliability and safety of existing solenoid valves, this invention provides a solenoid valve detection circuit, a control circuit, and a gas detector.

[0005] A solenoid valve detection circuit includes:

[0006] The detection control circuit is connected to the solenoid valve and receives externally input detection control signals and clock signals to control the application of a second power supply voltage for solenoid valve detection to the solenoid valve.

[0007] The signal acquisition circuit is connected to the detection and control circuit and the solenoid valve respectively, and is used to acquire the voltage sampling signal of the negative terminal of the solenoid valve.

[0008] The result comparison circuit, connected to the signal acquisition circuit, is used to compare the voltage sampling signal and the reference voltage signal to obtain and output the voltage comparison result.

[0009] Furthermore, the detection control circuit includes a signal inverting unit, a first MOSFET, and a second MOSFET;

[0010] The input terminal of the signal inversion unit is connected to the detection and control signal, and the output terminal of the signal inversion unit is connected to the input terminal of the signal acquisition circuit.

[0011] The gate of the first MOSFET is connected to the detection control signal, the source of the first MOSFET is connected to the positive terminal of the solenoid valve, and the drain of the first MOSFET is connected to the negative terminal of the solenoid valve.

[0012] The gate of the second MOSFET is connected to the clock signal, the drain of the second MOSFET is connected to the second power supply voltage, and the source of the second MOSFET is connected to the positive terminal of the solenoid valve.

[0013] Furthermore, the detection control circuit also includes a first resistor, which is connected in series on the connection line where the gate of the second MOSFET is connected to the clock signal.

[0014] Furthermore, the signal acquisition circuit includes a second resistor, a third MOSFET, and a fourth MOSFET;

[0015] The first end of the second resistor is connected to the negative terminal of the solenoid valve;

[0016] The drain of the third MOSFET is connected to the second terminal of the second resistor, the gate of the third MOSFET serves as the input terminal of the signal acquisition circuit to be connected to the output terminal of the detection and control circuit, and the source of the third MOSFET is grounded.

[0017] The drain of the fourth MOSFET is connected to the negative terminal of the solenoid valve, the gate of the fourth MOSFET is connected to the gate of the third MOSFET, and the source of the fourth MOSFET serves as the output terminal of the signal acquisition circuit to be connected to the input terminal of the result comparison circuit.

[0018] Furthermore, the signal acquisition circuit also includes a third resistor, which is connected in series on the connection line between the gate of the third MOSFET and the third output terminal of the detection and control circuit.

[0019] Furthermore, the result comparison circuit includes a first voltage divider unit, a second voltage divider unit, and a comparison unit;

[0020] The input terminal of the first voltage divider unit is connected to the second power supply voltage, and the output terminal of the first voltage divider unit is connected to the first negative connection terminal of the comparator unit, which is used to divide the second power supply voltage to form the first voltage division result and input it to the first negative connection terminal of the comparator unit.

[0021] The input terminal of the second voltage divider unit is connected to the second power supply voltage, and the output terminal of the second voltage divider unit is connected to the second positive connection terminal of the comparator unit. It is used to divide the second power supply voltage to form a second voltage division result and input it to the second positive connection terminal of the comparator unit. The reference voltage signal includes the first voltage division result and the second voltage division result.

[0022] The first positive connection terminal and the second negative connection terminal of the comparison unit are respectively connected to the output terminal of the signal acquisition circuit;

[0023] The comparison unit is used to compare the voltage sampling signal at the input first positive connection terminal with the first voltage divider result at the input first negative connection terminal to obtain a first voltage comparison result, and the first output terminal of the comparison unit outputs the first comparison result;

[0024] The comparison unit is used to compare the voltage sampling signal at the input second negative connection terminal with the second voltage divider result at the input second positive connection terminal to obtain a second voltage comparison result. The second output terminal of the comparison unit outputs the second comparison result.

[0025] Furthermore, the first output terminal of the comparator is connected to the second power supply voltage via a first pull-up resistor;

[0026] The second output terminal of the comparator is connected to the second power supply voltage through a second pull-up resistor.

[0027] This utility model also provides a solenoid valve control circuit, including a processor, a switch control circuit, and a solenoid valve detection circuit as described above;

[0028] The processor is connected to the signal input terminal of the switch control circuit, and the output terminal of the switch control circuit is connected to the solenoid valve.

[0029] The processor is used to generate the switching control signal for the solenoid valve. The switching control circuit is used to control the working state of the solenoid valve. When the switching control signal is a power-off signal, the solenoid valve is not energized, and when the switching control signal is an energized signal, the solenoid valve is energized.

[0030] The first input terminal of the detection control circuit in the solenoid valve detection circuit is connected to the signal input terminal of the switch control circuit, and the second input terminal of the detection control circuit is connected to the clock signal. The detection control circuit uses the switch control signal as the detection control signal and controls the application of the second power supply voltage for solenoid valve detection to the solenoid valve according to the detection control signal and the clock signal.

[0031] Furthermore, the output of the result comparison circuit in the solenoid valve detection circuit is connected to the processor to send the voltage comparison result to the processor.

[0032] This utility model also provides a gas detector that uses a solenoid valve control circuit as described above.

[0033] The beneficial technical effects of this utility model are as follows: This utility model develops a new control circuit design scheme, which integrates an effective solenoid valve fault detection function, so as to promptly detect and handle faults that may occur during the operation of the solenoid valve, and ensure the stable operation of the system. Attached Figure Description

[0034] Figure 1 This is a circuit diagram of a solenoid valve switching control circuit in the prior art;

[0035] Figure 2 This is a circuit diagram of a solenoid valve detection circuit according to the present invention;

[0036] Figure 3 This is a simulation equivalent circuit diagram of a solenoid valve detection circuit of the present invention when the solenoid valve is in normal operation;

[0037] Figure 4 This is a simulation equivalent circuit diagram of a solenoid valve detection circuit of the present invention when the solenoid valve is short-circuited;

[0038] Figure 5 This is a simulation equivalent circuit diagram of a solenoid valve detection circuit according to the present invention when the solenoid valve is open-circuited. Detailed Implementation

[0039] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0042] See Figure 2 This utility model provides a solenoid valve detection circuit, including:

[0043] The detection control circuit is connected to the solenoid valve (CN3) and receives the externally input detection control signal (TEST OFF) and clock signal (CLOCK) to control the application of the second power supply voltage (VIN2) for detection of the solenoid valve (CN3).

[0044] The signal acquisition circuit is connected to the detection and control circuit and the solenoid valve (CN3) respectively, and is used to acquire the voltage sampling signal of the negative terminal of the solenoid valve (CN3);

[0045] The result comparison circuit, connected to the signal acquisition circuit, is used to compare the voltage sampling signal and the reference voltage signal to obtain and output the voltage comparison result.

[0046] This invention develops a new control circuit design scheme that integrates an effective solenoid valve fault detection function to promptly detect and handle potential faults that may occur during the operation of the solenoid valve, thereby ensuring the stable operation of the system.

[0047] Specifically, the second power supply voltage (VIN2) for performing the solenoid valve detection function can be 5V.

[0048] Furthermore, the detection control circuit includes a signal inverting unit, a first MOSFET (Q1), and a second MOSFET (Q2);

[0049] The input terminal of the signal inversion unit is connected to the detection and control signal, and the output terminal of the signal inversion unit is connected to the input terminal of the signal acquisition circuit.

[0050] The gate of the first MOSFET (Q1) is connected to the detection control signal, the source of the first MOSFET (Q1) is connected to the positive terminal (OUT+) of the solenoid valve, and the drain of the first MOSFET (Q1) is connected to the negative terminal (OUT-) of the solenoid valve.

[0051] The gate of the second MOSFET (Q2) is connected to the clock signal (CLOCK), the drain of the second MOSFET (Q2) is connected to the second supply voltage (VIN2), and the source of the second MOSFET (Q2) is connected to the positive terminal (OUT+) of the solenoid valve (CN3).

[0052] In the solenoid valve control circuit, the switching control circuit controls the operating state of the solenoid valve according to the switching control signal (VALVE ON). When the switching control signal (VALVE ON) is de-energized, the solenoid valve is not energized; when the switching control signal (VALVE ON) is energized, the solenoid valve is energized. When the solenoid valve is not energized, the solenoid valve detection function is activated according to the input detection control signal and clock signal. When the solenoid valve is energized, the solenoid valve detection function is deactivated. The activated solenoid valve detection function performs open-circuit and short-circuit detection.

[0053] When the solenoid valve is working, it is usually powered on with a first working voltage of 12V (VIN1). In a preferred embodiment of this utility model, the detection control circuit in the solenoid valve detection circuit uses a switch control signal (VALVE ON) as the detection control signal (TEST OFF). At this time, the detection control circuit uses two MOSFETs to prevent the 12V first working voltage (VIN1) from flowing back into the 5V second supply voltage (VIN2), and can adjust the energizing time of the detection control circuit.

[0054] Specifically, both the first MOSFET (Q1) and the second MOSFET (Q2) are NMOS transistors.

[0055] Specifically, the signal inverting unit consists of two parts, U2B and U2A, such as... Figure 2 As shown. The U2B section mainly receives the second power supply voltage (VIN2) to power the signal inversion unit, while the U2A section mainly inverts the detection control signal TEST OFF. The TEST ON signal is obtained by inverting the TEST OFF signal.

[0056] Furthermore, the detection control circuit also includes a first resistor (R1), which is connected in series on the gate connection line of the second MOSFET (Q2) to receive the clock signal (CLOCK).

[0057] Furthermore, the signal acquisition circuit includes a second resistor (R2), a third MOSFET (Q3), and a fourth MOSFET (Q4);

[0058] The first end of the second resistor (R2) is connected to the negative terminal (OUT-) of the solenoid valve (CN3);

[0059] The drain of the third MOSFET (Q3) is connected to the second terminal of the second resistor (R2), the gate of the third MOSFET (Q3) serves as the input terminal of the signal acquisition circuit to connect to the output terminal of the detection control circuit, and the source of the third MOSFET (Q3) is grounded.

[0060] The drain of the fourth MOSFET (Q4) is connected to the negative terminal (OUT-) of the solenoid valve (CN3), the gate of the fourth MOSFET (Q4) is connected to the gate of the third MOSFET (Q3), and the source of the fourth MOSFET (Q4) serves as the output terminal of the signal acquisition circuit to be connected to the input terminal of the result comparison circuit.

[0061] Specifically, the third MOSFET (Q3) and the fourth MOSFET (Q4) are both NMOS transistors.

[0062] During short-circuit and open-circuit detection of the solenoid valve (CN3), the voltage divider between the second resistor (R2) and the solenoid valve is controlled to obtain a voltage sampling signal related to the solenoid valve. The TEST ON signal is used to control the conduction of the third MOSFET (Q3) and the fourth MOSFET (Q4). During the non-voltage sampling signal sampling period, the TEST ON signal is low, i.e., in a non-conducting state. At this time, the circuits of the third MOSFET (Q3) and the fourth MOSFET (Q4) are in a non-operating state, not affecting the original solenoid valve switching control circuit. During the voltage sampling signal sampling period, the TEST OFF signal is low. After inversion, the TEST ON signal becomes an on signal. At this time, the signal acquisition circuit starts to work and acquires the voltage sampling signal, which is then obtained using a result comparison circuit.

[0063] Furthermore, the signal acquisition circuit also includes a third resistor (R3), which is connected in series on the connection line between the gate of the third MOSFET (Q3) and the third output terminal of the detection control circuit.

[0064] Furthermore, the result comparison circuit includes a first voltage divider unit, a second voltage divider unit, and a comparison unit (U1);

[0065] The input terminal of the first voltage divider unit is connected to the second power supply voltage (VIN2), and the output terminal of the first voltage divider unit is connected to the first negative connection terminal of the comparator unit (U1), which is used to divide the second power supply voltage (VIN2) to form the first voltage division result and input it to the first negative connection terminal of the comparator unit (U1);

[0066] The input terminal of the second voltage divider unit is connected to the second supply voltage (VIN2), and the output terminal of the second voltage divider unit is connected to the second positive connection terminal of the comparator unit (U1). The second voltage divider unit is used to divide the second supply voltage to form a second voltage divider result and input it to the second positive connection terminal of the comparator unit (U1). The reference voltage signal includes the first voltage divider result and the second voltage divider result.

[0067] The first positive connection terminal and the second negative connection terminal of the comparison unit (U1) are respectively connected to the output terminal of the signal acquisition circuit;

[0068] The comparison unit (U1) is used to compare the voltage sampling signal of the input first positive connection terminal with the first voltage division result of the input first negative connection terminal to obtain the first voltage comparison result. The first output terminal (OUT1) of the comparison unit outputs the first voltage comparison result (SC).

[0069] The comparison unit (U1) is used to compare the voltage sampling signal at the input second negative connection terminal with the second voltage divider result at the input second positive connection terminal to obtain the second voltage comparison result. The second output terminal (OUT2) of the comparison unit (U1) outputs the second voltage comparison result (OC).

[0070] Furthermore, the first output terminal (OUT1) of the comparator unit (U1) is connected to the second supply voltage (VIN2) through the first pull-up resistor (R4);

[0071] The second output terminal (OUT2) of the comparator unit (U1) is connected to the second supply voltage (VIN2) through the second pull-up resistor (R5).

[0072] Specifically, the first voltage divider unit includes a sixth resistor (R6) and a seventh resistor (R7). The first end of the sixth resistor (R6) is connected to the second supply voltage (VIN2), the second end of the sixth resistor (R6) is connected to the first negative connection terminal of the comparator unit (U1), the first end of the seventh resistor (R7) is connected to the second end of the sixth resistor (R6), and the second end of the seventh resistor (R7) is grounded.

[0073] Specifically, the second voltage divider unit includes an eighth resistor (R8) and a ninth resistor (R9). The first end of the eighth resistor (R8) is connected to the second supply voltage (VIN2), and the second end of the eighth resistor (R8) is connected to the second positive connection terminal of the comparator unit (U1). The first end of the ninth resistor (R9) is connected to the second end of the sixth resistor (R6), and the second end of the ninth resistor (R9) is grounded.

[0074] The partial voltage value in the first partial voltage result is greater than the partial voltage value in the second partial voltage result.

[0075] Specifically, the first voltage comparison result is the short-circuit detection result signal (SC), and the second voltage comparison result is the open-circuit detection result signal (OC).

[0076] When the clock signal is high, if the voltage sampling signal is greater than the first voltage divider result, the first output terminal (OUT1) of the comparison unit (U1) outputs a high-level signal SC, indicating a short-circuit fault in the solenoid valve. If the voltage sampling signal is definitely greater than the second voltage divider result, the second output terminal (OUT2) of the comparison unit (U1) outputs a low-level signal OC.

[0077] When the clock signal is high, if the voltage sampling signal is smaller than the second voltage divider result, the second output terminal (OUT2) of the comparison unit (U1) outputs a high-level signal OC, indicating that the solenoid valve has an open circuit fault. At this time, the voltage sampling signal is definitely smaller than the second voltage divider result, and the first output terminal (OUT1) of the comparison unit (U1) outputs a low-level signal SC.

[0078] When the clock signal is high-level detection, if the voltage sampling signal is between the first voltage divider result and the second voltage divider result, then the first output terminal (OUT1) of the comparison unit (U1) outputs a low-level signal SC, and the second output terminal (OUT2) of the comparison unit (U1) outputs a low-level signal OC.

[0079] Specifically, the second supply voltage is 5V, the resistance of the second resistor (R2) is 22Ω, the resistance of the sixth resistor (R6) is 13KΩ, the resistance of the seventh resistor (R7) is 36Ω, the resistance of the eighth resistor (R8) is 43KΩ, and the resistance of the ninth resistor (R9) is 10KΩ. Therefore, the voltage division result of the first voltage divider is approximately 36 / (13+36)*5V = 3.67V, and the voltage division result of the second voltage divider is approximately 10 / (43+10)*5V = 0.94V.

[0080] Specifically, the resistance value of the second resistor (R2) can be 22Ω. The equivalent resistance ER1 of the solenoid valve sample was measured to be approximately 14Ω.

[0081] The simulations considered the voltage drop across the second transistor (Q2). The voltage applied to the solenoid valve must be less than the second supply voltage; that is, the source voltage of the second transistor (Q2) must be less than the 5V drain voltage. For example... Figure 3-5 The source of the second transistor (Q2) is approximately equivalent to 4.04V, 4.01V, and 4.46V, respectively.

[0082] See Figure 3 Simulation results and Figure 1-2If CLOCK is high, U11 is equivalent to the first comparator of the comparison unit, and U12 is equivalent to the second comparator of the comparison unit. If VALVE_ON is low, it means that the first 12V operating voltage (VIN1) is applied to the solenoid valve through the switch control circuit, energizing the solenoid valve. Therefore, TEST OFF is also low, and TEST ON is high because the inverse of TEST OFF is high. At this time, the first MOSFET (Q1) is energized because of TEST OFF. When the OFF level is low, the second MOSFET (Q2) is turned on, and the third and fourth MOSFETs are also turned on. If the solenoid valve is functioning normally and there is no short circuit or open circuit, the equivalent resistance ER1 is close to 14Ω, and the second equivalent resistance (ER2) is equivalent to 22Ω. The voltage sampling signal output is approximately 2.47V, which is between 3.67V and 0.94V, i.e., between the first voltage divider result and the second voltage divider result. The first output terminal of the comparator unit outputs a low level (approximately 76.3mV after pull-up resistor R4). Therefore, the voltage sampling signal is lower than the first voltage divider result, and the second output terminal OC of the comparator unit outputs a low level (approximately 76.3mV after pull-up resistor R5).

[0083] See Figure 4 Simulation results and Figure 1-2 If CLOCK is high and VALVE_ON is low, it means that the first working voltage of 12V (VIN1) is applied to the solenoid valve through the switch control circuit, energizing the solenoid valve. TEST OFF is also low, and TEST ON is high because it is the inverse of TEST OFF. At this time, the first MOSFET (Q1) is not conducting because TEST OFF is low, so the second MOSFET (Q2) conducts, and the third and fourth MOSFETs conduct. If the solenoid valve has a short circuit fault, the equivalent resistance ER1 is very low, close to 0.1Ω. At this time, the voltage sampling signal is about 3.99V, which is higher than the first voltage division result. The first output terminal OUT1 of the comparator unit outputs a high level SC (about 4.985V after pull-up resistor R4). At this time, the voltage sampling signal is higher than the second voltage division result, and the second output terminal OUT2 of the comparator unit outputs a low level OC (about 76.3mV after pull-up resistor R5).

[0084] See Figure 5 Simulation results and Figure 1-2If CLOCK is high and VALVE_ON is low, it means that the first working voltage of 12V (VIN1) is applied to the solenoid valve through the switch control circuit, energizing the solenoid valve. TEST OFF is also low, and TEST ON is high because it is the inverse of TEST OFF. At this time, the first MOSFET (Q1) is not conducting because TEST OFF is low, the second MOSFET (Q2) is conducting, and the third and fourth MOSFETs are conducting. If the solenoid valve fails to open, the equivalent resistance ER1 is approximately infinite Ω. At this time, the voltage sampling signal is approximately 979.56μV, which is lower than the first voltage division result. The first output terminal OUT1 of the comparator unit outputs a low level SC (approximately 76.3mV after pull-up resistor R4). At this time, the voltage sampling signal is lower than the second voltage division result, and the second output terminal OUT2 of the comparator unit outputs a high level OC (approximately 4.985V after pull-up resistor R5).

[0085] If VALVE_ON is low, it means that the first working voltage of 12V (VIN1) is applied to the solenoid valve through the switch control circuit, energizing the solenoid valve. TEST OFF is also low. TEST ON is high because the inverse of TEST OFF is high. At this time, the first MOSFET (Q1) is not turned on because TEST OFF is low. If CLOCK is low, the second MOSFET (Q2) is not turned on. At this time, the detection function is not executed when the solenoid valve is not energized. Although the third and fourth MOSFETs are turned on, the voltage sampling signal is also low. At this time, the voltage sampling signal is lower than the first voltage division result, so the first output terminal of the comparison unit is low (SC). The voltage sampling signal is lower than the second voltage division result, so the second output terminal of the comparison unit is high (OC).

[0086] If VALVE_ON is high, it means that the first working voltage of 12V (VIN1) is not applied to the solenoid valve through the switch control circuit, so that the solenoid valve is not energized. Then TEST OFF is also high. TEST ON is low because the inverted TEST OFF is low. At this time, the third and fourth MOSFETs are not conducting. The source terminal of the fourth MOSFET is low. The SC terminal of the first output terminal of the comparator is low, and the OC terminal of the second output terminal of the comparator is high.

[0087] According to simulations, when the internal resistance of the solenoid valve is 65Ω, the voltage sampling signal when the solenoid valve is operating normally is slightly greater than the second voltage divider result, therefore it will not trigger the detection result indicating that the solenoid valve is open-circuited. When the internal resistance of the solenoid valve is 0.5Ω, the voltage sampling signal when the solenoid valve is operating normally is slightly greater than the first voltage divider result, just triggering the detection result indicating that the solenoid valve is short-circuited. Without considering errors, the simulated internal resistance range of the solenoid valve can reach 0.5-65Ω, while the actual internal resistance of a solenoid valve is usually 5-15Ω. Therefore, this design is applicable to most solenoid valves.

[0088] Specifically, the relevant experiments of the signals of this utility model are shown in Table 1 below. In the table, "mode" represents the operating mode of the entire solenoid valve control circuit; "CLOCK" represents the clock signal input to the solenoid valve detection circuit; "VALVE_ON" represents the solenoid valve's on / off control signal (high level indicates no power to the solenoid valve, low level indicates power to the solenoid valve); "TEST OFF" represents the detection control signal; "TEST ON" represents the inversion of the detection control signal; "OC" represents the open-circuit detection result signal (high level indicates the solenoid valve is open-circuited); "SC" represents the short-circuit detection result signal (high level indicates the solenoid valve is short-circuited); "H" represents a high level; and "L" represents a low level.

[0089] Table 1

[0090] model CLOCK VALVE_ON TEST OFF TEST ON OC SC Normal detected H L L H L L Detection function not enabled L L L H H L The solenoid valve is not energized. L H H L H L Short circuit detected H L L H L H Open circuit detected H L L H H L

[0091] This shows that the experimental and simulation results are consistent.

[0092] This utility model also provides a solenoid valve control circuit, including a processor, a switch control circuit, and a solenoid valve detection circuit as described above;

[0093] The processor is connected to the signal input terminal of the switch control circuit, and the output terminal of the switch control circuit is connected to the solenoid valve (CN3).

[0094] The processor is used to generate the switching control signal (VALVE ON) for the solenoid valve. The switching control circuit is used to control the working state of the solenoid valve. When the switching control signal is a power-off signal, the solenoid valve is not energized, and when the switching control signal is an energized signal, the solenoid valve is energized.

[0095] The first input terminal of the detection control circuit in the solenoid valve detection circuit is connected to the signal input terminal of the switch control circuit, and the second input terminal of the detection control circuit is connected to the clock signal (CLOCK). The detection control circuit uses the switch control signal (VALVE ON) as the detection control signal (TEST OFF), and controls the application of the second power supply voltage for solenoid valve (CN3) detection to the solenoid valve according to the detection control signal (TEST OFF) and the clock signal (CLOCK).

[0096] Solenoid valves come in two types: normally open and normally closed. For normally open valves, the valve is open when no current flows through the solenoid coil, allowing the medium to flow; when the solenoid coil is energized, the valve closes, preventing the medium from flowing. For normally closed valves, the valve is closed when no current flows through the solenoid coil, preventing the medium from flowing; when the solenoid coil is energized, the valve opens, allowing the medium to flow.

[0097] The switch control circuit controls the operating state of the solenoid valve based on the switch control signal (VALVE ON). When the switch control signal is de-energized, the solenoid valve is not energized; when the switch control signal is energized, the solenoid valve is energized. When the solenoid valve is de-energized, the solenoid valve's detection function is activated based on the input detection control signal and clock signal; when the solenoid valve is energized, the detection function is de-energized.

[0098] Furthermore, the output of the result comparison circuit in the solenoid valve detection circuit is connected to the processor to send the voltage comparison result to the processor.

[0099] This utility model also provides a gas detector that uses a solenoid valve control circuit as described above.

[0100] This invention can be applied to household combustible gas detectors. It can be installed inside the household combustible gas detector. The solenoid valve detection circuit is integrated with the original solenoid valve control circuit. Alternatively, the solenoid valve detection circuit can be installed between the household combustible gas detector and the solenoid valve as an independent module.

[0101] The above are merely preferred embodiments of the present utility model and are not intended to limit the implementation methods and protection scope of the present utility model. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A solenoid valve detection circuit, characterized in that, include: A detection control circuit is connected to the solenoid valve and receives externally input detection control signals and clock signals to control the application of a second power supply voltage for solenoid valve detection to the solenoid valve. A signal acquisition circuit is connected to the detection and control circuit and the solenoid valve respectively, and is used to acquire the voltage sampling signal of the negative terminal of the solenoid valve; The result comparison circuit, connected to the signal acquisition circuit, is used to compare the voltage sampling signal and the reference voltage signal to obtain and output the voltage comparison result.

2. The solenoid valve detection circuit as described in claim 1, characterized in that, The detection control circuit includes a signal inversion unit, a first MOSFET, and a second MOSFET. The input terminal of the signal inversion unit is connected to the detection control signal, and the output terminal of the signal inversion unit is connected to the input terminal of the signal acquisition circuit. The gate of the first MOS transistor is connected to the detection control signal, the source of the first MOS transistor is connected to the positive terminal of the solenoid valve, and the drain of the first MOS transistor is connected to the negative terminal of the solenoid valve. The gate of the second MOS transistor is connected to the clock signal, the drain of the second MOS transistor is connected to the second power supply voltage, and the source of the second MOS transistor is connected to the positive terminal of the solenoid valve.

3. The solenoid valve detection circuit as described in claim 2, characterized in that, The detection and control circuit further includes a first resistor, which is connected in series on the connection line where the gate of the second MOS transistor is connected to the clock signal.

4. The solenoid valve detection circuit as described in claim 1, characterized in that, The signal acquisition circuit includes a second resistor, a third MOSFET, and a fourth MOSFET; The first end of the second resistor is connected to the negative terminal of the solenoid valve; The drain of the third MOS transistor is connected to the second terminal of the second resistor, the gate of the third MOS transistor serves as the input terminal of the signal acquisition circuit and is connected to the output terminal of the detection and control circuit, and the source of the third MOS transistor is grounded. The drain of the fourth MOS transistor is connected to the negative terminal of the solenoid valve, the gate of the fourth MOS transistor is connected to the gate of the third MOS transistor, and the source of the fourth MOS transistor serves as the output terminal of the signal acquisition circuit to be connected to the input terminal of the result comparison circuit.

5. The solenoid valve detection circuit as described in claim 4, characterized in that, The signal acquisition circuit also includes a third resistor, which is connected in series on the connection line between the gate of the third MOS transistor and the third output terminal of the detection and control circuit.

6. The solenoid valve detection circuit as described in claim 1, characterized in that, The result comparison circuit includes a first voltage divider unit, a second voltage divider unit, and a comparison unit; The input terminal of the first voltage divider unit is connected to the second power supply voltage, and the output terminal of the first voltage divider unit is connected to the first negative connection terminal of the comparator unit, for dividing the second power supply voltage to form a first voltage division result and inputting it to the first negative connection terminal of the comparator unit; The input terminal of the second voltage divider unit is connected to the second power supply voltage, and the output terminal of the second voltage divider unit is connected to the second positive connection terminal of the comparator unit. The second voltage divider unit is used to divide the second power supply voltage to form a second voltage divider result, which is then input to the second positive connection terminal of the comparator unit. The reference voltage signal includes the first voltage divider result and the second voltage divider result. The first positive connection terminal and the second negative connection terminal of the comparison unit are respectively connected to the output terminal of the signal acquisition circuit. The comparison unit is used to compare the voltage sampling signal input to the first positive connection terminal with the first voltage division result input to the first negative connection terminal to obtain a first voltage comparison result, and the first output terminal of the comparison unit outputs the first voltage comparison result; The comparison unit is used to compare the voltage sampling signal input to the second negative connection terminal with the second voltage divider result input to the second positive connection terminal to obtain a second voltage comparison result, and the second output terminal of the comparison unit outputs the second voltage comparison result.

7. The solenoid valve detection circuit as described in claim 6, characterized in that, The first output terminal of the comparison unit is connected to the second power supply voltage through a first pull-up resistor; The second output terminal of the comparison unit is connected to the second power supply voltage through a second pull-up resistor.

8. A solenoid valve control circuit, characterized in that, Includes a processor, a switch control circuit, and a solenoid valve detection circuit as described in any one of claims 1-7; The processor is connected to the signal input terminal of the switch control circuit, and the output terminal of the switch control circuit is connected to the solenoid valve. The processor is used to generate a switching control signal for the solenoid valve, and the switching control circuit is used to control the working state of the solenoid valve. When the switching control signal is a power-off signal, the solenoid valve is not energized, and when the switching control signal is an energized signal, the solenoid valve is energized. The first input terminal of the detection control circuit in the solenoid valve detection circuit is connected to the signal input terminal of the switch control circuit, and the second input terminal of the detection control circuit is connected to the clock signal. The detection control circuit uses the switch control signal as the detection control signal and controls the application of a second power supply voltage for solenoid valve detection to the solenoid valve according to the detection control signal and the clock signal.

9. A solenoid valve control circuit as described in claim 8, characterized in that, The output of the result comparison circuit in the solenoid valve detection circuit is connected to the processor, and is used to send the voltage comparison result to the processor.

10. A gas detector, characterized in that, Use a solenoid valve control circuit as described in any one of claims 8-9.

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