Automobile CNG mechanical pressure reducing valve test calibration circuit

Abstract

The utility model discloses an automobile CNG mechanical pressure reducing valve test calibration circuit which comprises a master control circuit, a stepping motor drive circuit, an injection rail drive circuit, an electromagnetic valve drive circuit and an analog quantity acquisition circuit. The stepping motor driving circuit, the injection rail driving circuit, the electromagnetic valve driving circuit and the analog quantity acquisition circuit are all electrically connected with the main control circuit, and the stepping motor driving circuit is used for driving a stepping motor to adjust a product pressure adjusting knob through air outlet pressure feedback during calibration. The injection rail driving circuit is used for simulating a plurality of nozzles on a real vehicle driving injection rail to perform injection actions, a key pressure gauge and the like are replaced with a battery valve and a pressure sensor, manual adjustment and calibration are changed into stepping motor adjustment, an air outlet is replaced with the injection rail on the vehicle during calibration, the state of the real vehicle is simulated, and calibration is more accurate. The automobile CNG mechanical pressure reducing valve test calibration circuit provided by the utility model has the effects of simulating the state of a real automobile and being more accurate in calibration.

Description

Technical Field

[0001] The utility model belongs to the technical field of automobile parameter calibration, and particularly relates to a test calibration circuit for an automobile CNG mechanical pressure reducing valve. Background Art

[0002] In the existing production process, the test calibration device for the automobile CNG mechanical pressure reducing valve adopts two independent devices. First, the pressure of the primary and secondary chambers is tested, and then the pressure calibration operation of the secondary chamber is carried out.

[0003] The pressure test station for the primary and secondary chambers is a purely manual operation station composed of a key switch and a pressure gauge. After high-pressure air is introduced, it is manually judged whether the pressure of the primary and secondary chambers is within a reasonable range by visually observing the pressure gauge, and the air outlet is manually opened to check the pressure gauge and the flow meter to judge the output pressure and flow of the secondary chamber.

[0004] For the pressure calibration operation of the secondary chamber, an operator also manually turns the pressure reducing valve pressure regulating knob while observing the output pressure until it is adjusted to a reasonable range.

[0005] The following problems exist in the prior art: 1. The manual detection efficiency is low, and the risk of human factors is relatively large; 2. The use of a solenoid valve at the air outlet end cannot well simulate the actual vehicle state, and the calibrated pressure is inaccurate. Summary of the Utility Model

[0006] In view of the above problems, a test calibration circuit for an automobile CNG mechanical pressure reducing valve is provided to solve the problems existing in the prior art.

[0007] The specific technical solution is as follows:

[0008] A test calibration circuit for an automobile CNG mechanical pressure reducing valve includes a main control circuit, a stepping motor drive circuit, a fuel rail drive circuit, a solenoid valve drive circuit, and an analog quantity acquisition circuit. The stepping motor drive circuit, the fuel rail drive circuit, the solenoid valve drive circuit, and the analog quantity acquisition circuit are all electrically connected to the main control circuit. The stepping motor drive circuit is used to drive a stepping motor to adjust the product pressure regulating knob through air outlet pressure feedback during calibration. The fuel rail drive circuit is used to simulate the actual vehicle to drive multiple nozzles on the fuel rail to perform injection actions. The solenoid valve drive circuit controls the on-off of the high-pressure solenoid valve at the air inlet. The analog quantity acquisition circuit is used to collect the signals of a high-precision pressure gauge.

[0009] The above-mentioned automotive CNG mechanical pressure reducing valve test and calibration circuit also has the following characteristics. The stepper motor drive circuit includes resistor R52, resistor R50, triode Q10, resistor R53, resistor R54, MOS transistor M5, resistor R51, and diode D11. The cathode of the diode D11 is electrically connected to an external 12V power supply. The anode of the diode D11 is electrically connected to the drain of the MOS transistor M5 through the resistor R51. The common terminal of the resistor R51 and the MOS transistor M5 serves as an output terminal and is electrically connected to the control terminal of the solenoid valve. The source of the MOS transistor M5 is grounded. The gate of the MOS transistor M5 is sequentially electrically connected to its source through the resistor R53 and the resistor R54. The common terminal of the resistor R53 and the resistor R54 is electrically connected to the collector of the triode Q10. The emitter of the triode Q10 is electrically connected to its base through the resistor R50. The base of the triode Q10 is used as an input terminal and is electrically connected to the main control circuit after passing through the resistor R52.

[0010] The above-mentioned automotive CNG mechanical pressure reducing valve test and calibration circuit also has the following characteristics. The fuel injector drive circuit includes a feedback circuit and multiple identical drive circuits to drive different nozzles to actuate.

[0011] The above-mentioned automotive CNG mechanical pressure reducing valve test and calibration circuit also has the following characteristics. The drive circuit includes resistor R12, resistor R5, triode Q1, resistor R14, resistor R18, MOS transistor M1, resistor R6, diode D2, diode D3, resistor R8, resistor R9, triode Q2, resistor R15, and resistor R19. The base of the triode Q1 is electrically connected to the main control circuit as the first signal input terminal after passing through the resistor R12. The base of the triode Q1 is also electrically connected to its emitter through the resistor R5. The emitter of the triode Q1 is also electrically connected to the external power supply VCC. The collector of the triode Q1 is electrically connected to the gate of the MOS transistor M1 through the resistor R14. The collector of the triode Q1 is also electrically connected to the source of the MOS transistor M1 through the resistor R18. The source of the MOS transistor M1 is grounded. The drain of the MOS transistor M1 is used as the drive signal output terminal and is electrically connected to the jet valve. The drain of the MOS transistor M1 is electrically connected to the anode of the diode D2 through the resistor R6. The cathode of the diode D2 is used as the output terminal and is electrically connected to the feedback circuit. The drain of the MOS transistor M1 is also electrically connected to the anode of the diode D3. The cathode of the diode D3 is sequentially connected to the resistor R8 and the resistor R9 and then used as the CT1 output terminal. The common terminal of the resistor R8 and the resistor R9 is electrically connected to the collector of the triode Q2. The emitter of the triode Q2 is electrically connected to its base through the resistor R19. The emitter of the triode Q2 is grounded. The base of the triode Q2 is electrically connected to the main control circuit as the second signal input terminal after passing through the resistor R15.

[0012] The above-mentioned automotive CNG mechanical pressure reducing valve test and calibration circuit also has the following characteristics. The feedback circuit includes diode D4, resistor R16, capacitor C12, resistor R11, resistor R7, resistor R17, comparator U4, resistor R10, and capacitor C13. The cathode of the diode D4 is electrically connected to the external VCC power supply. The anode of the diode D4 is grounded through the resistor R16. The common terminal of the diode D4 and the resistor R16 is used as the input terminal and is electrically connected to the cathode of the diode D2. The common terminal of the diode D4 and the resistor R16 is also grounded through the capacitor C12. The common terminal of the diode D4 and the resistor R16 is also electrically connected to the positive input terminal of the comparator U4 through the resistor R11. The negative input terminal of the comparator U4 is electrically connected to the external power supply VCC through the resistor R7. The negative input terminal of the comparator U4 is also grounded through the resistor R17. The output terminal of the comparator U4 is electrically connected to the external power supply VCC through the resistor R10. The output terminal of the comparator U4 is also grounded through the capacitor C13. The output terminal of the comparator U4 is electrically connected to the main control circuit.

[0013] The above-mentioned automotive CNG mechanical pressure reducing valve test and calibration circuit also has the following characteristics. The stepping motor drive circuit includes resistor R84, resistor R85, triode Q12, and capacitor C28. The base of the triode Q12 is electrically connected to the main control circuit as an input terminal after passing through the resistor R84. The base of the triode Q12 is also electrically connected to its emitter through the resistor R85. The emitter of the triode Q12 is grounded. The collector of the triode Q12 is grounded through the capacitor C28. The collector of the triode Q12 is also used as an output terminal to be electrically connected to the stepping motor control terminal to control the rotation speed and angle of the stepping motor;

[0014] The stepping motor drive circuit further includes resistor R86, resistor R87, triode Q13, and capacitor C29. The base of the triode Q13 is electrically connected to the main control circuit as an input terminal after passing through the resistor R86. The base of the triode Q13 is also electrically connected to its emitter through the resistor R87. The emitter of the triode Q13 is grounded. The collector of the triode Q13 is grounded through the capacitor C29. The collector of the triode Q13 is also used as an output terminal to be electrically connected to the stepping motor control terminal to control the rotation direction of the stepping motor;

[0015] The stepping motor drive circuit further includes resistor R88, resistor R89, triode Q14, and capacitor C30. The base of the triode Q14 is electrically connected to the main control circuit as an input terminal after passing through the resistor R88. The base of the triode Q14 is also electrically connected to its emitter through the resistor R89. The emitter of the triode Q14 is grounded. The collector of the triode Q14 is grounded through the capacitor C30. The collector of the triode Q14 is also used as an output terminal to be electrically connected to the stepping motor enable terminal.

[0016] The above-mentioned automotive CNG mechanical pressure reducing valve test and calibration circuit also has the following characteristics. The analog quantity acquisition circuit includes three-way pressure acquisition circuits and two-way temperature acquisition circuits. Each pressure acquisition circuit includes capacitor C18, resistor R74, resistor R75, and capacitor C19. The capacitor C18 is connected in parallel across the resistor R74. One common terminal of the capacitor C18 and the resistor R74 is grounded. The other common terminal of the capacitor C18 and the resistor R74 is used as a collection terminal to be electrically connected to the corresponding pressure gauge. The other common terminal of the capacitor C18 and the resistor R74 is sequentially grounded through the resistor R75 and the capacitor C19. The common terminal of the resistor R75 and the capacitor C19 is used as an output terminal to be electrically connected to the main control circuit;

[0017] The temperature acquisition circuit includes a capacitor C24, a resistor R80, a resistor R81, and a capacitor C25. The external power supply VCC is grounded sequentially through the resistor R80, the resistor R81, and the capacitor C25. The grounded terminal of the capacitor C25 is electrically connected to the common terminal of the resistor R80 and the resistor R81 through the capacitor C24. The common terminal of the resistor R80 and the capacitor C24 is used as an input terminal and is electrically connected to a pressure gauge. The common terminal of the resistor R81 and the capacitor C25 is used as an output terminal and is electrically connected to the main control circuit.

[0018] In summary, the beneficial effects of this solution are:

[0019] In the test and calibration circuit of the automotive CNG mechanical pressure reducing valve provided by the present invention, the key pressure gauge is replaced with a solenoid valve and a pressure sensor, and the manual adjustment and calibration are changed to the adjustment by a stepping motor. When calibrating, the gas outlet is replaced with the fuel rail on the vehicle to simulate the actual vehicle state, and the calibration is more accurate. The test and calibration circuit of the automotive CNG mechanical pressure reducing valve provided by the present invention has the effect of simulating the actual vehicle state and more accurate calibration. Description of the Drawings

[0020] Figure 1 It is a structural block diagram of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present invention;

[0021] Figure 2 It is a circuit structure diagram of the solenoid valve drive circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present invention;

[0022] Figure 3 It is a circuit structure diagram of the fuel rail drive circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present invention;

[0023] Figure 4 It is a circuit structure diagram of the stepping motor drive circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present invention;

[0024] Figure 5 It is a circuit structure diagram of the analog quantity acquisition circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present invention. Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0026] It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other.

[0027] The present utility model will be further described below in conjunction with specific embodiments, but it is not limited to the present utility model.

[0028] Figure 1 It is the structural block diagram of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present utility model. Figure 2 It is the circuit structure diagram of the solenoid valve drive circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present utility model. Figure 3 It is the circuit structure diagram of the fuel rail drive circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present utility model. Figure 4 It is the circuit structure diagram of the stepper motor drive circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present utility model. Figure 5 It is the circuit structure diagram of the analog quantity acquisition circuit of the test and calibration circuit of the automotive CNG mechanical pressure reducing valve of the present utility model. As Figures 1-4 shown, the test and calibration circuit of the automotive CNG mechanical pressure reducing valve provided in this embodiment includes a main control circuit, a stepper motor drive circuit, a fuel rail drive circuit, a solenoid valve drive circuit, and an analog quantity acquisition circuit. The stepper motor drive circuit, the fuel rail drive circuit, the solenoid valve drive circuit, and the analog quantity acquisition circuit are all electrically connected to the main control circuit. The stepper motor drive circuit is used to drive the stepper motor to adjust the product pressure regulating knob through the outlet pressure feedback during calibration. The fuel rail drive circuit is used to simulate the injection action of multiple nozzles on the fuel rail in actual vehicle driving. The solenoid valve drive circuit controls the on-off of the high-pressure solenoid valve at the air inlet. The analog quantity acquisition circuit is used to collect the signal of the high-precision pressure gauge.

[0029] In the above embodiment, the stepper motor drive circuit includes resistor R52, resistor R50, triode Q10, resistor R53, resistor R54, MOS transistor M5, resistor R51, and diode D11. The cathode of diode D11 is electrically connected to the external 12V power supply. The anode of diode D11 is electrically connected to the drain of MOS transistor M5 through resistor R51. The common terminal of resistor R51 and MOS transistor M5 is used as the output terminal and is electrically connected to the control terminal of the solenoid valve. The source of MOS transistor M5 is grounded. The gate of MOS transistor M5 is sequentially electrically connected to its source through resistor R53 and resistor R54. The common terminal of resistor R53 and resistor R54 is electrically connected to the collector of triode Q10. The emitter of triode Q10 is electrically connected to its base through resistor R50. The base of triode Q10 is electrically connected to the main control circuit as the input terminal through resistor R52.

[0030] In the above embodiment, the fuel rail drive circuit includes a feedback circuit and multiple identical drive circuits to drive different nozzles to act.

[0031] In the above embodiment, the drive circuit includes resistor R12, resistor R5, triode Q1, resistor R14, resistor R18, MOS transistor M1, resistor R6, diode D2, diode D3, resistor R8, resistor R9, triode Q2, resistor R15, and resistor R19. The base of triode Q1 is electrically connected to the main control circuit as the first signal input terminal after passing through resistor R12. The base of triode Q1 is also electrically connected to its emitter through resistor R5. The emitter of triode Q1 is also electrically connected to the external power supply VCC. The collector of triode Q1 is electrically connected to the gate of MOS transistor M1 through resistor R14. The collector of triode Q1 is also electrically connected to the source of MOS transistor M1 through resistor R18. The source of MOS transistor M1 is grounded. The drain of MOS transistor M1 is used as the drive signal output terminal and is electrically connected to the jet valve. The drain of MOS transistor M1 is electrically connected to the anode of diode D2 through resistor R6. The cathode of diode D2 is used as the output terminal and is electrically connected to the feedback circuit. The drain of MOS transistor M1 is also electrically connected to the anode of diode D3. The cathode of diode D3 is sequentially connected to resistor R8 and resistor R9 and then used as the CT1 output terminal. The common terminal of resistor R8 and resistor R9 is electrically connected to the collector of triode Q2. The emitter of triode Q2 is electrically connected to its base through resistor R19. The emitter of triode Q2 is grounded. The base of triode Q2 is electrically connected to the main control circuit as the second signal input terminal after passing through resistor R15.

[0032] It should be noted that the number of nozzles is four. Therefore, there are also four drive modules in the injection rail drive circuit, which correspond to the nozzles one by one.

[0033] In the above embodiment, the feedback circuit includes diode D4, resistor R16, capacitor C12, resistor R11, resistor R7, resistor R17, comparator U4, resistor R10, and capacitor C13. The cathode of diode D4 is electrically connected to the external VCC power supply. The anode of diode D4 is grounded through resistor R16. The common terminal of diode D4 and resistor R16 is used as the input terminal and is electrically connected to the cathode of diode D2. The common terminal of diode D4 and resistor R16 is also grounded through capacitor C12. The common terminal of diode D4 and resistor R16 is also electrically connected to the positive input terminal of comparator U4 through resistor R11. The negative input terminal of comparator U4 is electrically connected to the external power supply VCC through resistor R7. The negative input terminal of comparator U4 is also grounded through resistor R17. The output terminal of comparator U4 is electrically connected to the external power supply VCC through resistor R10. The output terminal of comparator U4 is also grounded through capacitor C13. The output terminal of comparator U4 is electrically connected to the main control circuit.

[0034] In the above embodiments, the stepper motor drive circuit includes a resistor R84, a resistor R85, a triode Q12, and a capacitor C28. The base of the triode Q12 is electrically connected to the main control circuit as an input terminal after passing through the resistor R84. The base of the triode Q12 is also electrically connected to its emitter through the resistor R85. The emitter of the triode Q12 is grounded. The collector of the triode Q12 is grounded through the capacitor C28. The collector of the triode Q12 is also used as an output terminal to be electrically connected to the stepper motor control terminal to control the rotation speed and angle of the stepper motor;

[0035] The stepper motor drive circuit further includes a resistor R86, a resistor R87, a triode Q13, and a capacitor C29. The base of the triode Q13 is electrically connected to the main control circuit as an input terminal after passing through the resistor R86. The base of the triode Q13 is also electrically connected to its emitter through the resistor R87. The emitter of the triode Q13 is grounded. The collector of the triode Q13 is grounded through the capacitor C29. The collector of the triode Q13 is also used as an output terminal to be electrically connected to the stepper motor control terminal to control the rotation direction of the stepper motor;

[0036] The stepper motor drive circuit further includes a resistor R88, a resistor R89, a triode Q14, and a capacitor C30. The base of the triode Q14 is electrically connected to the main control circuit as an input terminal after passing through the resistor R88. The base of the triode Q14 is also electrically connected to its emitter through the resistor R89. The emitter of the triode Q14 is grounded. The collector of the triode Q14 is grounded through the capacitor C30. The collector of the triode Q14 is also used as an output terminal to be electrically connected to the stepper motor enable terminal.

[0037] In the above embodiments, the analog quantity acquisition circuit includes three-way pressure acquisition circuits and two-way temperature acquisition circuits. The pressure acquisition circuit includes a capacitor C18, a resistor R74, a resistor R75, and a capacitor C19. The capacitor C18 is connected in parallel across the resistor R74. One of the common terminals of the capacitor C18 and the resistor R74 is grounded. The other common terminal of the capacitor C18 and the resistor R74 is used as the acquisition terminal to be electrically connected to the corresponding pressure gauge. The other common terminal of the capacitor C18 and the resistor R74 is sequentially grounded through the resistor R75 and the capacitor C19. The common terminal of the resistor R75 and the capacitor C19 is used as the output terminal to be electrically connected to the main control circuit;

[0038] The temperature acquisition circuit includes a capacitor C24, a resistor R80, a resistor R81, and a capacitor C25. The external power supply VCC is sequentially grounded through the resistor R80, the resistor R81, and the capacitor C25. The grounded terminal of the capacitor C25 is electrically connected to the common terminal of the resistor R80 and the resistor R81 through the capacitor C24. The common terminal of the resistor R80 and the capacitor C24 is used as the input terminal to be electrically connected to the pressure gauge. The common terminal of the resistor R81 and the capacitor C25 is used as the output terminal to be electrically connected to the main control circuit.

[0039] It should be noted that it also includes a serial port 485 communication circuit, which is used to connect and interact with the host computer.

[0040] Working principle: Replace the key pressure gauge with a solenoid valve and a pressure sensor, change the manual adjustment and calibration to stepper motor adjustment, replace the air outlet during calibration with the fuel rail on the vehicle, simulate the actual vehicle state, make the calibration more accurate, and adopt a self-developed control board to communicate and control with the host computer for overall control, so as to achieve automatic testing and avoid human factors.

[0041] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the content of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A test and calibration circuit for an automotive CNG mechanical pressure reducing valve, characterized in that: It includes a main control circuit, a stepper motor drive circuit, a fuel rail drive circuit, a solenoid valve drive circuit, and an analog quantity acquisition circuit. The stepper motor drive circuit, the fuel rail drive circuit, the solenoid valve drive circuit, and the analog quantity acquisition circuit are all electrically connected to the main control circuit. The stepper motor drive circuit is used to drive the stepper motor to adjust the product pressure regulating knob through the outlet air pressure feedback during calibration. The fuel rail drive circuit is used to simulate the actual vehicle to drive multiple nozzles on the fuel rail for injection actions. The solenoid valve drive circuit controls the on / off of the high-pressure solenoid valve at the air inlet. The analog quantity acquisition circuit is used to collect the signals of the high-precision pressure gauge.

2. The test calibration circuit of an automotive CNG mechanical pressure reducing valve according to claim 1, characterized in that: The stepper motor drive circuit includes a resistor R52, a resistor R50, a triode Q10, a resistor R53, a resistor R54, a MOS transistor M5, a resistor R51, and a diode D11. The cathode of the diode D11 is electrically connected to an external 12V power supply. The anode of the diode D11 is electrically connected to the drain of the MOS transistor M5 through the resistor R51. The common terminal of the resistor R51 and the MOS transistor M5 serves as an output terminal and is electrically connected to the control terminal of the solenoid valve. The source of the MOS transistor M5 is grounded. The gate of the MOS transistor M5 is sequentially electrically connected to its source through the resistor R53 and the resistor R54. The common terminal of the resistor R53 and the resistor R54 is electrically connected to the collector of the triode Q10. The emitter of the triode Q10 is electrically connected to its base through the resistor R50. The base of the triode Q10 is electrically connected to the main control circuit as an input terminal through the resistor R52.

3. The test calibration circuit of an automotive CNG mechanical pressure reducing valve according to claim 2, characterized in that: The fuel rail drive circuit includes a feedback circuit and multiple identical drive circuits to drive different nozzles to act.

4. A test and calibration circuit for an automotive CNG mechanical pressure reducing valve according to claim 3, characterized in that: The driving circuit includes resistor R12, resistor R5, triode Q1, resistor R14, resistor R18, MOS transistor M1, resistor R6, diode D2, diode D3, resistor R8, resistor R9, triode Q2, resistor R15, and resistor R19. The base of the triode Q1 is electrically connected to the main control circuit as a first signal input terminal after passing through the resistor R12. The base of the triode Q1 is also electrically connected to its emitter through the resistor R5. The emitter of the triode Q1 is also connected to the external power supply VCC. The collector of the triode Q1 is electrically connected to the gate of the MOS transistor M1 through the resistor R14. The collector of the triode Q1 is also electrically connected to the source of the MOS transistor M1 through the resistor R18. The source of the MOS transistor M1 is grounded. The drain of the MOS transistor M1 is used as a driving signal output terminal and is electrically connected to the jet valve. The drain of the MOS transistor M1 is electrically connected to the anode of the diode D2 through the resistor R6. The cathode of the diode D2 is used as an output terminal and is electrically connected to the feedback circuit. The drain of the MOS transistor M1 is also electrically connected to the anode of the diode D3. The cathode of the diode D3 is sequentially connected to the resistor R8 and the resistor R9 and then used as the CT1 output terminal. The common terminal of the resistor R8 and the resistor R9 is electrically connected to the collector of the triode Q2. The emitter of the triode Q2 is electrically connected to its base through the resistor R19. The emitter of the triode Q2 is grounded. The base of the triode Q2 is electrically connected to the main control circuit as a second signal input terminal after passing through the resistor R15.

5. The test calibration circuit of an automotive CNG mechanical pressure reducing valve according to claim 4, characterized in that: The feedback circuit includes diode D4, resistor R16, capacitor C12, resistor R11, resistor R7, resistor R17, comparator U4, resistor R10, and capacitor C13. The cathode of the diode D4 is connected to the external VCC power supply. The anode of the diode D4 is grounded through the resistor R16. The common terminal of the diode D4 and the resistor R16 is used as an input terminal and is electrically connected to the cathode of the diode D2. The common terminal of the diode D4 and the resistor R16 is also grounded through the capacitor C12. The common terminal of the diode D4 and the resistor R16 is also electrically connected to the positive input terminal of the comparator U4 through the resistor R11. The negative input terminal of the comparator U4 is connected to the external power supply VCC through the resistor R7. The negative input terminal of the comparator U4 is also grounded through the resistor R17. The output terminal of the comparator U4 is connected to the external power supply VCC through the resistor R10. The output terminal of the comparator U4 is also grounded through the capacitor C13. The output terminal of the comparator U4 is electrically connected to the main control circuit.

6. The test calibration circuit of an automotive CNG mechanical pressure reducing valve according to claim 5, characterized in that: The stepper motor drive circuit includes resistor R84, resistor R85, triode Q12, and capacitor C28. The base of triode Q12 is electrically connected to the main control circuit as an input terminal after passing through resistor R84. The base of triode Q12 is also electrically connected to its emitter through resistor R85. The emitter of triode Q12 is grounded. The collector of triode Q12 is grounded through capacitor C28. The collector of triode Q12 also serves as an output terminal and is electrically connected to the stepper motor control terminal to control the rotation speed and angle of the stepper motor; The stepper motor drive circuit further includes resistor R86, resistor R87, triode Q13, and capacitor C29. The base of triode Q13 is electrically connected to the main control circuit as an input terminal after passing through resistor R86. The base of triode Q13 is also electrically connected to its emitter through resistor R87. The emitter of triode Q13 is grounded. The collector of triode Q13 is grounded through capacitor C29. The collector of triode Q13 also serves as an output terminal and is electrically connected to the stepper motor control terminal to control the rotation direction of the stepper motor; The stepper motor drive circuit further includes resistor R88, resistor R89, triode Q14, and capacitor C30. The base of triode Q14 is electrically connected to the main control circuit as an input terminal after passing through resistor R88. The base of triode Q14 is also electrically connected to its emitter through resistor R89. The emitter of triode Q14 is grounded. The collector of triode Q14 is grounded through capacitor C30. The collector of triode Q14 also serves as an output terminal and is electrically connected to the stepper motor enable terminal.

7. A test calibration circuit for an automotive CNG mechanical pressure reducing valve according to any one of claims 1-6, characterized in that: The analog quantity acquisition circuit includes three-way pressure acquisition circuits and two-way temperature acquisition circuits. The pressure acquisition circuit includes capacitor C18, resistor R74, resistor R75, and capacitor C19. Capacitor C18 is connected in parallel across resistor R74. One common terminal of capacitor C18 and resistor R74 is grounded. The other common terminal of capacitor C18 and resistor R74 serves as the acquisition terminal and is electrically connected to the corresponding pressure gauge. The other common terminal of capacitor C18 and resistor R74 is sequentially grounded through resistor R75 and capacitor C19. The common terminal of resistor R75 and capacitor C19 serves as the output terminal and is electrically connected to the main control circuit; The temperature acquisition circuit includes capacitor C24, resistor R80, resistor R81, and capacitor C25. The external power supply VCC is sequentially grounded through resistor R80, resistor R81, and capacitor C25. The grounded terminal of capacitor C25 is electrically connected to the common terminal of resistor R80 and resistor R81 through capacitor C24. The common terminal of resistor R80 and capacitor C24 serves as the input terminal and is electrically connected to the pressure gauge. The common terminal of resistor R81 and capacitor C25 serves as the output terminal and is electrically connected to the main control circuit.

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