An ultrasonic ranging circuit and fuel consumption meter

Abstract

The application discloses an ultrasonic ranging circuit, which comprises a pulse transformer T, a socket XS2, an ultrasonic transmitting circuit, an ultrasonic receiving circuit and a tail wave elimination circuit; the primary side of the pulse transformer T is connected with the ultrasonic transmitting circuit, the ultrasonic receiving circuit and the tail wave elimination circuit respectively; the secondary side of the pulse transformer T is connected with an ultrasonic probe through the socket XS2; the ultrasonic transmitting circuit is used for signal amplification of ultrasonic signals generated by a single-chip microcomputer to form transmitting waves; the tail wave elimination circuit is used for energy release of the primary side of the pulse transformer T to eliminate tail waves of the transmitting waves; and the ultrasonic receiving circuit is used for conversion of received ultrasonic signals into electric signals and filtering and amplification processing. The application further discloses an oil consumption instrument. The application solves the technical problem that the existing ultrasonic ranging cannot eliminate tail waves of transmitting waves and has a ranging blind area, so that the ultrasonic ranging cannot be accurately performed.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic ranging technology, and more particularly to an ultrasonic ranging circuit and a fuel consumption meter. Background Technology

[0002] Ultrasonic ranging works by emitting ultrasonic waves from an ultrasonic transmitter and multiplying the time difference between the emitted wave and the reflected echo by the speed of sound in the medium, similar to radar ranging. The ultrasonic transmitter emits ultrasonic waves in a specific direction, and timing begins simultaneously with the emission. The ultrasonic waves propagate through the air, returning immediately upon encountering an obstacle. The ultrasonic receiver stops timing upon receiving the reflected wave. However, during ultrasonic ranging, energy storage components in the transmitting circuit, such as coils, create a wake wave. If the distance is below a certain fixed value, the wake wave and the reflected echo overlap, making it impossible to measure the true distance. This distance below the fixed value is called the blind zone. Therefore, there is an urgent need to develop an ultrasonic ranging circuit and fuel consumption meter to solve the technical problem of existing ultrasonic ranging methods failing to eliminate the wake wave, resulting in a blind zone and inaccurate ultrasonic ranging. Summary of the Invention

[0003] The main objective of this invention is to propose an ultrasonic ranging circuit and fuel consumption meter, aiming to solve the technical problem that existing ultrasonic ranging methods cannot eliminate the wake wave of the emitted wave, resulting in a ranging blind zone and thus failing to accurately perform ultrasonic ranging.

[0004] To achieve the above objectives, the present invention provides an ultrasonic ranging circuit, wherein the ultrasonic ranging circuit comprises:

[0005] Pulse transformer T, ultrasonic transmitting circuit, ultrasonic receiving circuit, and wake wave elimination circuit;

[0006] The primary side of the pulse transformer T is connected to the ultrasonic transmitting circuit, the ultrasonic receiving circuit, and the wake wave cancellation circuit, respectively; the secondary side of the pulse transformer T is connected to the ultrasonic probe.

[0007] The ultrasonic transmitting circuit amplifies the ultrasonic signal generated by the microcontroller to form a transmitted wave; the wake cancellation circuit discharges the energy on the primary side of the pulse transformer T to eliminate the wake of the transmitted wave; the ultrasonic receiving circuit converts the received ultrasonic signal into an electrical signal and performs filtering and amplification processing.

[0008] In one preferred embodiment, the wake cancellation circuit includes resistor R51, resistor R52, a level conversion circuit, and MOS switch Q2;

[0009] One end of resistor R51 is connected to the power supply terminal, and the other end of resistor R51 is connected to the microcontroller control terminal and resistor R52 respectively. The other end of resistor R52 is connected to the level conversion circuit, and the other end of the level conversion circuit is connected to the gate of MOS switch Q2. The drain of MOS switch Q2 is connected to pin 2 of pulse transformer T, and the source of MOS switch Q2 is connected to pin 1 of pulse transformer T.

[0010] In one preferred embodiment, the level conversion circuit includes a resistor R53 and a MOSFET V19; one end of the resistor R53 is connected to the power supply terminal, and the other end of the resistor R53 is connected to the drain of the MOSFET V19 and the gate of the MOSFET switch Q2, respectively; the gate of the MOSFET V19 is connected to the resistor R52, and the source of the MOSFET V19 is grounded.

[0011] In one preferred embodiment, the ultrasonic transmitting circuit includes a resistor R16, a resistor R19, a voltage amplification circuit, a current amplification circuit, and a MOSFET V7. One end of the resistor R16 is connected to the power supply terminal, and the other end of the resistor R16 is connected to the microcontroller control terminal and the resistor R19. The other end of the resistor R19 is connected to the voltage amplification circuit, and the other end of the voltage amplification circuit is connected to pin 1 of the pulse transformer T and the current amplification circuit. The other end of the current amplification circuit is connected to pin 1 of the pulse transformer T and the gate of the MOSFET V7. The drain of the MOSFET V7 is connected to pin 2 of the pulse transformer T, and the source of the MOSFET V7 is grounded.

[0012] In one preferred embodiment, the voltage amplification circuit includes a resistor R1 and a MOSFET V3. One end of the resistor R1 is connected to the power supply terminal and pin 1 of the pulse transformer T, respectively. The other end of the resistor R1 is connected to the drain of the MOSFET V3 and the current amplification circuit. The gate of the MOSFET V3 is connected to a resistor R19, and the source of the MOSFET V3 is grounded.

[0013] In one preferred embodiment, the current amplification circuit includes transistors V2 and V4; the collector of transistor V2 is connected to pin 1 of the pulse transformer T, the emitter of transistor V2 is connected to the emitter of transistor V4 and the gate of MOSFET V7, the base of transistor V2 is connected to the voltage amplification circuit and the base of transistor V4, and the collector of transistor V4 is grounded.

[0014] In one preferred embodiment, the ultrasonic receiving circuit includes a first amplification and filtering circuit, which is connected to the pulse transformer T.

[0015] The first amplification and filtering circuit includes amplifier D3; pin 1 of amplifier D3 is connected to resistor R13 and capacitor C9 respectively; the other end of capacitor C9 is connected to resistor R15; the other end of resistor R15 is connected to resistor R26, capacitor C16 and capacitor C19 respectively; the other end of capacitor C16 is connected to resistor R30 and pin 7 of amplifier D3 respectively; the other end of resistor R30 is connected to the other end of capacitor C19 and pin 6 of amplifier D3 respectively.

[0016] The amplifier D3 has pin 2 connected to the other end of resistor R13 and resistor R12 respectively; the other end of resistor R12 is connected to the clamping circuit and capacitor C5 respectively; and the other end of capacitor C5 is connected to pin 2 of pulse transformer T.

[0017] The amplifier D3 has its pin 3 connected to resistor R18, and the other end of resistor R18 is connected to capacitor C18, pin 4 of amplifier D3, and ground.

[0018] The 8 pins of amplifier D3 are connected to the power supply.

[0019] The amplifier D3 has pin 5, resistor R26, and the other end of capacitor C18 grounded.

[0020] In one preferred embodiment, the ultrasonic receiving circuit further includes a second amplification and filtering circuit, which is connected to the first amplification circuit; the second amplification circuit includes amplifier D4.

[0021] Pin 1 of amplifier D4 is connected to resistor R31, and the other end of resistor R31 is grounded.

[0022] Pin 2 of amplifier D4 is connected to capacitor C28, and the other end of capacitor C28 is grounded.

[0023] The amplifier D4 has its 3rd pin connected to capacitor bank R28 and capacitor C17 respectively. The other end of capacitor C17 is connected to the microcontroller. The other end of resistor R28 is connected to the 4th pin of amplifier D4.

[0024] The 4th pin of amplifier D4 is connected to resistor R29, and the other end of resistor R29 is connected to the 7th pin of amplifier D3 through capacitor C25.

[0025] Pin 5 of the amplifier D4 is connected to the power supply.

[0026] In one preferred embodiment, the ultrasonic receiving circuit further includes a comparator circuit; the comparator circuit is connected to the second amplifier circuit and the microcontroller respectively; the second amplifier circuit includes a comparator D2;

[0027] Pin 1 of the comparator D2 is connected to resistor R20, resistor R24 ​​and capacitor C24 respectively. The other end of resistor R20 is connected to the power supply terminal, and the other ends of capacitor C24 and resistor R24 ​​are grounded.

[0028] The three pins of the comparator D2 are connected to resistors R17 and R14 respectively and the second amplifier circuit. The other end of resistor R17 is connected to the power supply terminal, and the other end of resistor R14 is grounded.

[0029] The four pins of the comparator D2 are connected to resistors R25, R23 and C22 respectively. The other end of resistor R25 is connected to the power supply, the other end of resistor R23 is connected to the microcontroller, and the other end of capacitor C22 is grounded.

[0030] Pin 2 of the comparator D2 is grounded, and pin 5 of the comparator D2 is connected to the power supply.

[0031] The present invention provides a fuel consumption meter, wherein the fuel consumption meter includes the aforementioned ultrasonic ranging circuit.

[0032] In the above technical solution of the present invention, the ultrasonic ranging circuit includes: a pulse transformer T, an ultrasonic transmitting circuit, an ultrasonic receiving circuit, and a wake wave elimination circuit; the primary side of the pulse transformer T is connected to the ultrasonic transmitting circuit, the ultrasonic receiving circuit, and the wake wave elimination circuit respectively; the secondary side of the pulse transformer T is connected to the ultrasonic probe; the ultrasonic transmitting circuit is used to amplify the ultrasonic signal generated by the microcontroller to form a transmitted wave; the wake wave elimination circuit is used to discharge the energy of the primary side of the pulse transformer T to eliminate the wake wave of the transmitted wave; the ultrasonic receiving circuit is used to convert the received ultrasonic signal into an electrical signal and perform filtering and amplification processing. The present invention, by setting a wake wave elimination circuit on the primary side of the pulse transformer T to discharge energy from the primary coil of the pulse transformer T, eliminates or shortens the wake wave of the transmitted wave, solving the technical problem that existing ultrasonic ranging methods cannot eliminate the wake wave of the transmitted wave, resulting in a ranging blind zone and thus failing to accurately perform ultrasonic ranging. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of an ultrasonic ranging circuit according to an embodiment of the present invention;

[0035] Figure 2 This is a circuit diagram of an ultrasonic ranging circuit according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the first amplification and filtering circuit and the second amplification and filtering circuit according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the comparison circuit in an embodiment of the present invention.

[0038] Explanation of icon numbers:

[0039] 1. Pulse transformer T; 2. Ultrasonic transmitting circuit; 3. Ultrasonic receiving circuit; 4. Wake wave cancellation circuit; 5. Ultrasonic probe.

[0040] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0043] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0044] See Figures 1-4 According to one aspect of the present invention, an ultrasonic ranging circuit is provided, wherein the ultrasonic ranging circuit comprises:

[0045] Pulse transformer T1, ultrasonic transmitting circuit 2, ultrasonic receiving circuit 3, and wake wave elimination circuit 4;

[0046] The primary side of the pulse transformer T1 is connected to the ultrasonic transmitting circuit 2, the ultrasonic receiving circuit 3, and the wake wave cancellation circuit 4, respectively; the secondary side of the pulse transformer T1 is connected to the ultrasonic probe 5.

[0047] The ultrasonic transmitting circuit 2 is used to amplify the ultrasonic signal generated by the microcontroller to form a transmitted wave; the wake cancellation circuit 4 is used to discharge the energy on the primary side of the pulse transformer T1 to eliminate the wake of the transmitted wave; the ultrasonic receiving circuit 3 is used to convert the received ultrasonic signal into an electrical signal and perform filtering and amplification processing.

[0048] Specifically, in this embodiment, the tailwave elimination circuit 4 includes resistor R51, resistor R52, a level conversion circuit, and MOS switch Q2. One end of resistor R51 is connected to the power supply terminal, and the other end of resistor R51 is connected to the microcontroller control terminal and resistor R52 respectively. The other end of resistor R52 is connected to the level conversion circuit, and the other end of the level conversion circuit is connected to the gate of MOS switch Q2. The drain of MOS switch Q2 is connected to pin 2 of pulse transformer T1, and the source of MOS switch Q2 is connected to pin 1 of pulse transformer T1. Resistors R51 and R52 are current-limiting resistors to prevent excessive current from damaging the circuit components. A 2MHz pulse is emitted by the microcontroller, immediately setting the wave_off1 signal high. At this time, MOS switch Q2 is turned on, and the primary coil of pulse transformer T1 discharges energy through MOS switch Q2, eliminating the tailwave. After 20µs, the receive interrupt is enabled, reducing the dead zone to (20µs / 2)*10. -6 *1250*10 2 =1.25cm, which greatly reduces the blind spot.

[0049] Specifically, in this embodiment, the level conversion circuit includes a resistor R53 and a MOSFET V19; one end of the resistor R53 is connected to the power supply terminal, and the other end of the resistor R53 is connected to the drain of the MOSFET V19 and the gate of the MOSFET switch Q2, respectively; the gate of the MOSFET V19 is connected to the resistor R52, and the source of the MOSFET V19 is grounded; one end of the resistor R51 is connected to the 3V power supply terminal, and the level conversion circuit can convert the 3.3V power supply to a 10V power supply output.

[0050] Specifically, in this embodiment, the ultrasonic transmitting circuit 2 includes a resistor R16, a resistor R19, a voltage amplification circuit, a current amplification circuit, and a MOSFET V7. One end of the resistor R16 is connected to the power supply terminal, and the other end of the resistor R16 is connected to the microcontroller control terminal and the resistor R19. The other end of the resistor R19 is connected to the voltage amplification circuit, and the other end of the voltage amplification circuit is connected to pin 1 of the pulse transformer T1 and the current amplification circuit. The other end of the current amplification circuit is connected to pin 1 of the pulse transformer T1 and the gate of the MOSFET V7. The drain of the MOSFET V7 is connected to pin 2 of the pulse transformer T1, and the source of the MOSFET V7 is grounded. The tx_wave signal is output through the GPIO pin of the microcontroller. The tx_wave signal is a 2MHz high-level pulse signal. When the microcontroller is not in control, the input of the ultrasonic transmitting circuit 2 is low-level. The pulse signal is amplified by voltage and current through the ultrasonic transmitting circuit 2, and then transmitted by the ultrasonic probe 5 through the pulse transformer T1. When detecting the remaining oil level in the tank using ultrasound, the microcontroller sends a 2MHz pulse signal. Due to the energy stored in the coil of the pulse transformer and the parasitic capacitance of the MOS transistor V7, the transmitted wave waveform is a 2MHz sine wave lasting several hundred microseconds. If the oil level is not high enough, the echo and the transmitted wave are easily mixed, making it impossible to measure the oil level. The indistinguishable distance is the blind zone. Calculated at 200µs, the blind zone is (200µs / 2)*10. -6 *1250*10 2 =12.5cm, while the fuel tank height of a typical engineering vehicle is 80cm-100cm, resulting in a large blind zone; when the ultrasonic transmitting circuit 2 is combined with the tail wave elimination circuit 4, after the microcontroller transmits a 2M pulse signal, the wave_off1 signal is immediately set, and the drain and source of the MOS switch Q2 are connected. The energy stored in the primary coil of the pulse transformer T1 is released through short circuit, shortening the time of the transmitted wave tail wave.

[0051] Specifically, in this embodiment, the voltage amplification circuit includes a resistor R1 and a MOSFET V3. One end of the resistor R1 is connected to the power supply terminal and pin 1 of the pulse transformer T1, and the other end of the resistor R1 is connected to the drain of the MOSFET V3 and the current amplification circuit. The gate of the MOSFET V3 is connected to a resistor R19, and the source of the MOSFET V3 is grounded. The voltage amplification circuit can convert the input 3.3V voltage into a 10V voltage output.

[0052] Specifically, in this embodiment, the current amplification circuit includes transistors V2 and V4; the collector of transistor V2 is connected to pin 1 of pulse transformer T1, the emitter of transistor V2 is connected to the emitter of transistor V4 and the gate of MOSFET V7, the base of transistor V2 is connected to the voltage amplification circuit and the base of transistor V4, and the collector of transistor V4 is grounded; the input current signal is amplified by the current amplification circuit to increase the energy of the transmitted wave, and then the pulse signal is transmitted to pulse transformer T1 for transmission by ultrasonic probe 5.

[0053] Specifically, in this embodiment, the ultrasonic receiving circuit 3 includes a first amplification and filtering circuit, which is connected to the pulse transformer T1; the first amplification and filtering circuit includes an amplifier D3; pin 1 of the amplifier D3 is connected to resistor R13 and capacitor C9 respectively; the other end of capacitor C9 is connected to resistor R15; the other end of resistor R15 is connected to resistor R26, capacitor C16, and capacitor C19 respectively; the other end of capacitor C16 is connected to resistor R30 and pin 7 of the amplifier D3 respectively; the other end of resistor R30 is connected to the other end of capacitor C19 and pin 6 of the amplifier D3 respectively; pin 2 of the amplifier D3 is connected to the other end of resistor R13 and resistor R12 respectively; the other end of resistor R12 is connected to the clamping circuit respectively. The amplifier D3 is connected to capacitor C5, and the other end of capacitor C5 is connected to pin 2 of pulse transformer T1. Capacitor C5 is used to block DC, isolate high-frequency signals and low-frequency signals, so that DC cannot pass through. Pin 3 of amplifier D3 is connected to resistor R18, and the other end of resistor R18 is connected to capacitor C18, capacitor C23, pin 4 of amplifier D3 and ground respectively. Pin 8 of amplifier D3 is connected to the power supply, capacitor C8 and capacitor C13 respectively, and the other ends of capacitor C8 and capacitor C13 are grounded. Pin 5 of amplifier D3, resistor R26, capacitor C18 and the other end of capacitor C23 are grounded. The weak electrical signal of the echo is amplified and filtered by the first amplification and filtering circuit, with an amplification factor of about 100 times. The high-pass filter is used to select the 2M ultrasonic signal.

[0054] Specifically, in this embodiment, the clamping circuit includes diode V5, diode V6 and resistor R10. One end of diode V5, diode V6 and resistor R10 is connected to resistor R12, and the other end of diode V5, diode V6 and resistor R10 is grounded. The clamping circuit fixes the pulse signal part at a specified voltage value and keeps the original waveform shape unchanged.

[0055] Specifically, in this embodiment, the ultrasonic receiving circuit 3 further includes a second amplification and filtering circuit, which is connected to the first amplification circuit. The second amplification circuit includes an amplifier D4. Pin 1 of the amplifier D4 is connected to a resistor R31, and the other end of the resistor R31 is grounded. Pin 2 of the amplifier D4 is connected to a capacitor C28, and the other end of the capacitor C28 is grounded. Pin 3 of the amplifier D4 is connected to a capacitor bank R28 and a capacitor C17, and the other end of the capacitor C17 is connected to a microcontroller. The other end of the resistor R28 is connected to pin 4 of the amplifier D4. Pin 4 of the amplifier D4 is connected to a resistor R29, and the other end of the resistor R29 is connected to pin 7 of the amplifier D3 through a capacitor C25. Pin 5 of the amplifier D4 is connected to a power supply terminal, a capacitor C12, and a capacitor C15, and the other ends of the capacitors C12 and C15 are grounded. The second amplification and filtering circuit amplifies the signal from the first amplification and filtering circuit a second time to obtain the final reflected echo signal.

[0056] Specifically, in this embodiment, the ultrasonic receiving circuit 3 further includes a comparison circuit; the comparison circuit is connected to the second amplification circuit and the microcontroller respectively; the second amplification circuit includes a comparator D2; pin 1 of the comparator D2 is connected to resistors R20, R24, and capacitors C27 and C24 respectively, the other end of resistor R20 is connected to the power supply terminal, and the other ends of capacitors C24, C27, and resistor R24 ​​are grounded; pin 3 of the comparator D2 is connected to resistors R17 and R14 and the second amplification circuit respectively, the other end of resistor R17 is connected to the power supply terminal, and the other end of resistor R14 is grounded; pin 4 of the comparator D2 is connected to resistors R25 and R23 and capacitor C22 respectively, the other end of resistor R25 is connected to the power supply terminal, and the other end of resistor R14 is grounded; pin 4 of the comparator D2 is connected to resistors R25 and R23 and capacitor C22 respectively, the other end of resistor R25 is connected to the power supply terminal, and the other end of resistor R24 ​​... connected to the power supply terminal, and the other end of resistor R24 ​​is connected to the power supply terminal, and the other end of resistor R24 ​​is connected to the power supply terminal, and the other end of resistor R25 is connected to the power supply terminal, and the other end of resistor R24 ​​is connected to the power supply terminal, and the other end of resistor R24 ​​is connected to the power supply terminal, and the other end of resistor R25 is connected to the power supply terminal, and the other end of resistor R24 ​​is connected The other end is connected to the power supply terminal, the other end of the resistor R23 is connected to the microcontroller, and the other end of the capacitor C22 is grounded; pin 2 of the comparator D2 is grounded, and pin 5 of the comparator D2 is connected to capacitor C20, capacitor C24 and the power supply terminal respectively, and the other ends of capacitor C20 and capacitor C24 are grounded; when the echo of the ultrasonic wave returns to the probe, the ultrasonic probe 5 converts the echo energy into a weak electrical signal, which is then filtered and amplified and compared with the comparison voltage set by the comparator circuit. If the signal is greater than the comparison voltage, it indicates that the reflected echo signal has been received. The comparator outputs the first rising edge, generating an interrupt signal to the microcontroller. The microcontroller records the time of the transmitted wave and the time of the received interrupt signal. The time difference is the time it takes for the ultrasonic wave to travel in the medium.

[0057] According to another aspect of the present invention, a fuel consumption meter is provided, wherein the fuel consumption meter includes the aforementioned ultrasonic ranging circuit.

[0058] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An ultrasonic ranging circuit, characterized in that, The ultrasonic ranging circuit includes: a pulse transformer T, an ultrasonic transmitting circuit, an ultrasonic receiving circuit, and a wake wave elimination circuit. The primary side of the pulse transformer T is connected to the ultrasonic transmitting circuit, the ultrasonic receiving circuit, and the wake wave cancellation circuit, respectively; the secondary side of the pulse transformer T is connected to the ultrasonic probe. The ultrasonic transmitting circuit amplifies the ultrasonic signal generated by the microcontroller to form a transmitted wave; the wake cancellation circuit discharges the energy on the primary side of the pulse transformer T to eliminate the wake of the transmitted wave; the ultrasonic receiving circuit converts the received ultrasonic signal into an electrical signal and performs filtering and amplification processing. The wake cancellation circuit includes resistor R51, resistor R52, level conversion circuit, and MOS switch Q2; one end of resistor R51 is connected to the power supply terminal, the other end of resistor R51 is connected to the microcontroller control terminal and resistor R52 respectively, the other end of resistor R52 is connected to the level conversion circuit, the other end of the level conversion circuit is connected to the gate of MOS switch Q2, the drain of MOS switch Q2 is connected to pin 2 of pulse transformer T, and the source of MOS switch Q2 is connected to pin 1 of pulse transformer T. The level conversion circuit includes a resistor R53 and a MOSFET V19; one end of the resistor R53 is connected to the power supply terminal, and the other end of the resistor R53 is connected to the drain of the MOSFET V19 and the gate of the MOSFET switch Q2, respectively; the gate of the MOSFET V19 is connected to the resistor R52, and the source of the MOSFET V19 is grounded. The ultrasonic transmitting circuit includes resistor R16, resistor R19, voltage amplification circuit, current amplification circuit, and MOSFET V7. One end of resistor R16 is connected to the power supply terminal, and the other end of resistor R16 is connected to the microcontroller control terminal and resistor R19. The other end of resistor R19 is connected to the voltage amplification circuit. The other end of the voltage amplification circuit is connected to pin 1 of pulse transformer T and the current amplification circuit. The other end of the current amplification circuit is connected to pin 1 of pulse transformer T and the gate of MOSFET V7. The drain of MOSFET V7 is connected to pin 2 of pulse transformer T, and the source of MOSFET V7 is grounded. The voltage amplification circuit includes a resistor R1 and a MOSFET V3. One end of the resistor R1 is connected to the power supply terminal and pin 1 of the pulse transformer T, respectively. The other end of the resistor R1 is connected to the drain of the MOSFET V3 and the current amplification circuit. The gate of the MOSFET V3 is connected to a resistor R19, and the source of the MOSFET V3 is grounded. The current amplification circuit includes transistors V2 and V4; the collector of transistor V2 is connected to pin 1 of the pulse transformer T, the emitter of transistor V2 is connected to the emitter of transistor V4 and the gate of MOSFET V7, the base of transistor V2 is connected to the voltage amplification circuit and the base of transistor V4, and the collector of transistor V4 is grounded.

2. The ultrasonic ranging circuit according to claim 1, characterized in that, The ultrasonic receiving circuit includes a first amplification and filtering circuit, which is connected to the pulse transformer T. The first amplification and filtering circuit includes amplifier D3; pin 1 of amplifier D3 is connected to resistor R13 and capacitor C9 respectively; the other end of capacitor C9 is connected to resistor R15; the other end of resistor R15 is connected to resistor R26, capacitor C16 and capacitor C19 respectively; the other end of capacitor C16 is connected to resistor R30 and pin 7 of amplifier D3 respectively; the other end of resistor R30 is connected to the other end of capacitor C19 and pin 6 of amplifier D3 respectively. The amplifier D3 has pin 2 connected to the other end of resistor R13 and resistor R12 respectively; the other end of resistor R12 is connected to the clamping circuit and capacitor C5 respectively; and the other end of capacitor C5 is connected to pin 2 of pulse transformer T. The amplifier D3 has its pin 3 connected to resistor R18, and the other end of resistor R18 is connected to capacitor C18, pin 4 of amplifier D3, and ground. The 8 pins of amplifier D3 are connected to the power supply. The amplifier D3 has pin 5, resistor R26, and the other end of capacitor C18 grounded.

3. The ultrasonic ranging circuit according to claim 2, characterized in that, The ultrasonic receiving circuit further includes a second amplification and filtering circuit, which is connected to the first amplification and filtering circuit; the second amplification and filtering circuit includes amplifier D4. Pin 1 of amplifier D4 is connected to resistor R28 and capacitor C17 respectively. The other end of capacitor C17 is connected to the microcontroller, and the other end of resistor R28 is connected to pin 4 of amplifier D4. Pin 2 of amplifier D4 is connected to capacitor C28, and the other end of capacitor C28 is grounded. The amplifier D4 has its pin 3 connected to resistor R31, and the other end of resistor R31 is grounded. The 4th pin of amplifier D4 is connected to resistor R29, and the other end of resistor R29 is connected to the 7th pin of amplifier D3 through capacitor C25. Pin 5 of the amplifier D4 is connected to the power supply.

4. The ultrasonic ranging circuit according to claim 2, characterized in that, The ultrasonic receiving circuit further includes a comparison circuit; the comparison circuit is connected to the second amplification and filtering circuit and the microcontroller respectively; the comparison circuit includes comparator D2; Pin 1 of the comparator D2 is connected to resistor R20, resistor R24 ​​and capacitor C24 respectively. The other end of resistor R20 is connected to the power supply terminal, and the other ends of capacitor C24 and resistor R24 ​​are grounded. The three pins of the comparator D2 are connected to resistors R17 and R14 respectively, and the second amplification and filtering circuit. The other end of resistor R17 is connected to the power supply terminal, and the other end of resistor R14 is grounded. The four pins of the comparator D2 are connected to resistors R25, R23 and C22 respectively. The other end of resistor R25 is connected to the power supply, the other end of resistor R23 is connected to the microcontroller, and the other end of capacitor C22 is grounded. Pin 2 of the comparator D2 is grounded, and pin 5 of the comparator D2 is connected to the power supply.

5. A fuel consumption meter, characterized in that, The fuel consumption meter includes an ultrasonic ranging circuit as described in any one of claims 1-4.

Images