Resistance detection circuit and oil level detection system

Abstract

The embodiment of the application provides a resistance detection circuit and an oil level detection system. The resistance detection circuit is located outside a fuel tank, and comprises a sampling control unit, a voltage division resistance unit and a micro control unit. The sampling control unit is connected with a power supply, the sampling control unit is connected with a first end of the voltage division resistance unit, a second end of the voltage division resistance unit is connected with a liquid level sensor, the micro control unit is connected with the voltage division resistance unit, and the micro control unit is connected with the sampling control unit. The voltage division resistance unit is used to share the input voltage in the resistance detection circuit with the liquid level sensor. The micro control unit is used to control the detection opening or the detection closing of the resistance detection circuit through the sampling control unit, and when the detection is opened, the resistance value of the liquid level sensor is determined through the voltage division voltage of the voltage division resistance unit. The method is used to improve the safety of the sensor.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to a resistance detection circuit and an oil level detection system. Background Technology

[0002] The liquid level sensor in the fuel tank is generally a float-type / resistive sensor. The liquid level sensor can be based on the principle of buoyancy, where the float moves up and down with the liquid level, triggering a change in the resistance value.

[0003] In related technologies, resistive detection circuits can inject a DC voltage with a voltage divider resistor into the level sensor, detect the voltage across the sensor, and calculate the sensor's resistance using the voltage divider theorem. However, the continuous current flowing through the level sensor generates power consumption, causing the sensor inside the tank to heat up, thus compromising the sensor's safety. Utility Model Content

[0004] This application provides a resistance detection circuit and an oil level detection system to improve the safety of sensor use.

[0005] In a first aspect, embodiments of this application provide a resistance detection circuit located outside the fuel tank. The resistance detection circuit includes a sampling control unit, a voltage divider resistor unit, and a microcontroller unit. The sampling control unit is connected to a power supply and is connected to a first terminal of the voltage divider resistor unit. The second terminal of the voltage divider resistor unit is connected to a liquid level sensor. The microcontroller unit is connected to the voltage divider resistor unit and also to the sampling control unit.

[0006] The voltage divider resistor unit is used to share the input voltage in the resistance detection circuit with the liquid level sensor;

[0007] The microcontroller unit is used to control the detection of the resistance detection circuit to be turned on or off through the sampling control unit, and when the detection is turned on, to determine the resistance value of the liquid level sensor through the voltage divider of the voltage divider unit.

[0008] In one possible implementation, the microcontroller is used to send a sampling frequency control signal to the sampling control unit;

[0009] The sampling control unit is used to control the detection of the resistance detection circuit to be turned on or off according to the sampling frequency control signal.

[0010] In one possible implementation, the sampling control unit includes a drive switch;

[0011] The drive switch is activated if the sampling frequency control signal is a sampling signal, so as to control the detection of the resistance detection circuit.

[0012] The drive switch is also used to turn off if the sampling frequency control signal is a non-sampling signal, so as to control the detection shutdown of the resistance detection circuit.

[0013] In one possible implementation, the driving switch includes a gate, a drain, and a source. The gate is connected to the microcontroller unit, the drain is connected to the power supply, and the source is connected to the voltage divider resistor unit. The sampling control unit further includes a first resistor and a second resistor.

[0014] The first resistor is disposed between the microcontroller and the gate, and the first resistor is used to limit the peak value of the drive current of the microcontroller.

[0015] The second resistor is disposed between the gate and the drain, and is used to adjust the impedance between the gate and the drain to limit the reflection of the sampling frequency control signal.

[0016] In one possible implementation, the microcontroller unit is provided with a digital-to-analog converter, a first pin of the digital-to-analog converter is connected to one end of the voltage divider resistor unit, and a second pin of the digital-to-analog converter is connected to the other end of the voltage divider resistor unit.

[0017] The first pin is used to detect the voltage at the first terminal of the voltage divider resistor unit, and the second pin is used to detect the voltage at the second terminal of the voltage divider resistor unit. The voltage divider voltage is the difference between the voltage at the first terminal and the voltage at the second terminal.

[0018] In one possible implementation, the microcontroller unit further includes a processing logic unit for determining the resistance value of the liquid level sensor using the voltage divider and the resistance value of the voltage divider resistor unit.

[0019] In one possible implementation, a first protection unit is provided between the first pin and the voltage divider resistor unit, and a second protection unit is provided between the second pin and the voltage divider resistor unit, wherein...

[0020] The first protection unit is used to protect the first port of the digital-to-analog converter connected to the first pin;

[0021] The second protection unit is used to protect the second port of the digital-to-analog converter connected to the second pin.

[0022] In one possible implementation, the microcontroller unit is further configured to control the drive switch to close when the liquid level sensor is detected to be grounded via the second pin of the digital-to-analog converter.

[0023] In one possible implementation, an anti-backflow diode is provided between the sampling control unit and the voltage divider resistor unit, wherein...

[0024] The anti-backflow diode is used to conduct electricity unidirectionally from the sampling control unit to the voltage divider resistor unit and to prevent current from flowing from the voltage divider resistor unit to the sampling control unit.

[0025] Secondly, embodiments of this application provide an oil level detection system, which includes a resistance detection circuit and a liquid level sensor as described in the first aspect, wherein the liquid level sensor is connected to the voltage divider resistor unit of the resistance detection circuit.

[0026] Thirdly, embodiments of this application provide a method for detecting resistance, comprising:

[0027] A sampling frequency control signal is sent to the sampling control unit, the sampling frequency control signal being used to indicate that the resistance value of the liquid level sensor is sampled at a preset frequency;

[0028] If the sampling frequency control signal is a sampling signal, then the voltage division of the voltage divider resistor unit is determined;

[0029] The resistance value of the liquid level sensor is determined based on the voltage divider and the resistance value of the voltage divider resistor unit.

[0030] Fourthly, this application provides a resistance detection device, which includes a transmitting module, a first determining module, and a second determining module 5, wherein...

[0031] The transmitting module is used to send a sampling frequency control signal to the sampling control unit;

[0032] The first determining module is used to determine the voltage divider voltage of the voltage divider resistor unit if the sampling frequency control signal is a sampling signal.

[0033] The second determining module is used to determine the resistance value of the liquid level sensor based on the voltage divider and the resistance value of the voltage divider resistor unit.

[0034] Fifthly, embodiments of this application provide an electronic device, including: a memory and a processor;

[0035] The memory stores computer-executed instructions;

[0036] The processor executes computer execution instructions stored in the memory, causing the processor to perform the implementation method described in the third aspect above.

[0037] Sixthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the embodiments described in the third aspect above.

[0038] In a seventh aspect, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the implementation methods described in the third aspect above.

[0039] The resistance detection circuit and fuel level detection system provided in this application embodiment are located outside the fuel tank. The resistance detection circuit includes a sampling control unit, a voltage divider resistor unit, and a microcontroller unit. The voltage divider resistor unit can share the input voltage in the resistance detection circuit with the fuel level sensor. The microcontroller unit is used to control the detection on or off of the resistance detection circuit through the sampling control unit. When detection is on, the microcontroller unit determines the resistance value of the fuel level sensor through the voltage divider resistor unit. The microcontroller unit can control the detection of the resistance detection circuit through the sampling control unit, eliminating the need for continuous power to the fuel level sensor and improving the safety of sensor use. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0041] Figure 1 A schematic diagram illustrating an application scenario provided in an embodiment of this application;

[0042] Figure 2 This is a schematic diagram of a resistance detection circuit provided in an embodiment of this application;

[0043] Figure 3 This is a schematic diagram of another resistance detection circuit provided in an embodiment of this application;

[0044] Figure 4 A schematic flowchart illustrating a resistance detection method provided in an embodiment of this application;

[0045] Figure 5 A schematic diagram of the structure of a resistance detection device provided in an embodiment of this application;

[0046] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0047] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0048] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0049] Figure 1 This is a schematic diagram illustrating an application scenario provided by an embodiment of this application. Please refer to [link / reference]. Figure 1 This includes the vehicle's fuel tank 101, level sensor 102, and resistance detection circuit 103.

[0050] A fuel level sensor 102 can be placed in the fuel tank 101. The fuel level sensor can be a float-type sensor or a resistive sensor. A float is incorporated into the fuel level sensor; based on the principle of buoyancy, the float rises and falls with the fuel level, triggering a change in the resistance value of the fuel level sensor. A resistance detection circuit 103 can be connected to the fuel level sensor 102 to detect the resistance value of the fuel level sensor 102 and determine the fuel level in the fuel tank 101 based on the resistance value of the fuel level sensor 102.

[0051] In existing technologies, resistive detection circuits inject a DC voltage with a voltage divider resistor into the level sensor, detect the voltage across the sensor, and calculate the sensor's resistance using the voltage divider theorem. However, the continuous flow of current through the level sensor generates power consumption, causing the sensor inside the tank to heat up, thus compromising its safety.

[0052] The resistance detection circuit provided in this embodiment is located outside the fuel tank. The resistance detection circuit includes a sampling control unit, a voltage divider resistor unit, and a microcontroller unit. The voltage divider resistor unit can share the input voltage in the resistance detection circuit with the liquid level sensor. The microcontroller unit, through the sampling control unit, controls the detection of the resistance detection circuit to be turned on or off. When detection is on, the microcontroller unit determines the resistance value of the liquid level sensor through the voltage divider resistor unit. The microcontroller unit can control the detection of the resistance detection circuit through the sampling control unit, eliminating the need for continuous power to the liquid level sensor and improving the safety of sensor use.

[0053] Figure 2 This is a schematic diagram of a resistance detection circuit provided in an embodiment of this application. Please refer to... Figure 2 The resistance detection circuit includes a sampling control unit, a voltage divider resistor unit, and a microcontroller unit. The sampling control unit is connected to a power supply. The sampling control unit is connected to the first terminal of the voltage divider resistor unit, the second terminal of the voltage divider resistor unit is connected to the liquid level sensor, the microcontroller unit is connected to the voltage divider resistor unit, and the microcontroller unit is connected to the sampling control unit.

[0054] The resistance of the level sensor changes with the level in the tank. When the level rises, the sensor's resistance decreases; when the level falls, the sensor's resistance increases.

[0055] When the liquid level sensor is detected by the resistance detection circuit, if the resistance of the liquid level sensor is high, the liquid level sensor will generate a lot of heat. Since the liquid level sensor is inside the fuel tank and in contact with the fuel, the large amount of heat will affect the safety of the vehicle.

[0056] A voltage divider resistor unit can be connected in series with the liquid level sensor. The voltage divider resistor unit can be used to share the input voltage in the resistance detection circuit with the liquid level sensor, which can reduce the voltage of the liquid level sensor in the resistance detection circuit, thereby reducing the heat generated by the liquid level sensor when detecting the liquid level in the tank.

[0057] The microcontroller unit is used to control the detection of the resistance detection circuit to be turned on or off through the sampling control unit.

[0058] Specifically, the microcontroller unit can send a sampling frequency control signal to the sampling control unit, which can then control the resistance detection circuit to turn on or off based on the sampling frequency control signal.

[0059] The sampling frequency control signal can include a sampling signal and a non-sampling signal. The sampling signal is used to control the detection of the resistance detection circuit to be turned on, and the non-sampling signal is used to control the detection of the resistance detection circuit to be turned off.

[0060] By using the sampling frequency control signal, the resistance detection circuit detects the resistance of the liquid level sensor according to the preset sampling frequency.

[0061] When the detection is activated, the microcontroller unit can determine the resistance value of the liquid level sensor by the voltage division of the voltage divider unit.

[0062] The voltage divider resistor unit can be a high-precision resistor. The resistance detection circuit can measure the resistance of the voltage divider resistor unit and thus determine the resistance value of the liquid level sensor, which can improve the accuracy of determining the resistance value of the liquid level sensor.

[0063] The resistance detection circuit provided in this application embodiment can send a sampling frequency control signal to the sampling control unit through the microcontroller unit to control the start and stop of the sampling control unit, thereby realizing the detection of the resistance detection circuit without continuously powering on the liquid level sensor, which can improve the safety of sensor use.

[0064] Figure 3 This is a schematic diagram of another resistance detection circuit provided in an embodiment of this application. Please refer to... Figure 3 The sampling control unit may include a drive switch, a first resistor, and a second resistor. The drive switch may include a gate, a drain, and a source. The gate is connected to the microcontroller unit, the drain is connected to a power supply, and the other end of the power supply is grounded (GND). The source is connected to a voltage divider resistor unit. The first resistor is positioned between the microcontroller unit and the gate, and the second resistor is positioned between the gate and the drain.

[0065] If the sampling frequency control signal is a sampling signal, the drive switch is activated to control the detection of the resistance detection unit; if the sampling frequency control signal is a non-sampling signal, the drive switch is deactivated to control the detection of the resistance detection unit.

[0066] The driving switch can be a controlled MOSFET switch. The controlled MOSFET switch can be based on the electric field effect control mechanism of the metal-oxide-semiconductor field-effect transistor (MOSFET). By adjusting the gate voltage to regulate the formation and disappearance of the conductive channel, the current on and off can be precisely controlled.

[0067] The first resistor can be used to limit the peak drive current of the microcontroller unit.

[0068] The second resistor can be used to adjust the impedance between the gate and drain to limit the reflection of the sampling frequency control signal.

[0069] Please see Figure 3 The first resistor is R7, the second resistor is R8, and the driving switch is Q1. The sampling frequency control signal can control the gate of transistor Q1 through resistor R7, thereby controlling the conduction state of Q1. When the sampling frequency control signal is high (i.e., the sampling signal), Q1 is turned on, and current I1 flows through the sensor; when the sampling frequency control signal is low (i.e., the non-sampling signal), Q1 is turned off, and current I1 is disconnected.

[0070] The microcontroller unit is equipped with an analog-to-digital converter (ADC), which can convert continuously changing analog signals (such as voltage and current) into discrete digital signals (binary values) so that the microcontroller unit can process and analyze them.

[0071] The digital-to-analog converter may include a first pin (ADC_SENSOR_P, Vp) and a second pin (ADC_SENSOR_N, Vn). The first pin is connected to one end of the voltage divider resistor unit, and the second pin is connected to the other end of the voltage divider resistor unit.

[0072] Please see Figure 3 The first pin (ADC_SENSOR_P) collects the voltage at the positive terminal of the sensor, and the second pin (ADC_SENSOR_N) collects the voltage at the negative terminal of the sensor.

[0073] The first pin can be used to detect the voltage at the first end of the voltage divider resistor unit, and the second pin can be used to detect the voltage at the second end of the voltage divider resistor unit. The voltage divider voltage is the difference between the voltage at the first end and the voltage at the second end.

[0074] In this embodiment, the ability to resist common-mode interference and improve sampling accuracy can be enhanced by differentially sampling the voltage of the voltage divider resistor unit.

[0075] A first protection unit is provided between the first pin and the voltage divider resistor unit, and a second protection unit is provided between the second pin and the voltage divider resistor unit.

[0076] The first protection unit protects the first port of the digital-to-analog converter connected to the first pin by converting the voltage drop of the voltage divider resistor unit into a voltage range suitable for the input of the digital-to-analog converter. Please refer to [link to relevant documentation]. Figure 3 The first protection unit includes resistors R2 and R3. The resistance ratio of R2 and R3 determines the range of the input voltage of the digital-to-analog converter. Resistor R3 is grounded.

[0077] Similarly, the second protection unit protects the second port of the digital-to-analog converter connected to the second pin by converting the voltage drop of the voltage divider resistor unit into a voltage range suitable for the input of the digital-to-analog converter. See also... Figure 3 The second protection unit includes resistors R4 and R5. The resistance ratio of R4 and R5 determines the range of the input voltage of the digital-to-analog converter. Resistor R5 is grounded.

[0078] The first and second protection units serve to protect the hydraulic sensor. Taking the first protection unit as an example, if the resistance of the hydraulic sensor is too low, and the resistance of the first protection unit is also too small, it may cause excessive current to flow across the hydraulic sensor, thereby damaging the sensor. Therefore, the resistance of the first protection unit should be much greater than the resistance of the hydraulic sensor to limit the current flowing across it.

[0079] On the other hand, the sum of the resistance values ​​of the first protection unit is much greater than the resistance value of the hydraulic sensor, and the sum of the resistance values ​​of the second protection unit is much greater than the resistance value of the hydraulic sensor. This ensures that the voltage drop across the sensor accurately reflects the resistance change of the hydraulic sensor, thereby improving measurement accuracy.

[0080] Taking the first protection unit as an example, when the resistance of the first protection unit is much greater than the resistance of the hydraulic sensor, the voltage drop across the hydraulic sensor will be mainly determined by the resistance of the hydraulic sensor, while the effect of the resistance change of the first protection unit on the voltage drop across the hydraulic sensor can be ignored. Therefore, the voltage signal acquired by the digital-to-analog converter will more accurately reflect the resistance change of the hydraulic sensor, thereby improving the measurement accuracy.

[0081] For example, when the signal from the hydraulic sensor is shorted to the vehicle's battery, the first and second protection units can prevent backflow and damage to the digital-to-analog converter port.

[0082] The microcontroller unit is also used to control the drive switch to turn off when the liquid level sensor is detected to be grounded via the second pin of the digital-to-analog converter.

[0083] For example, see Figure 3 When the signal from the hydraulic sensor is shorted to ground (GND), it can be detected by the second pin (ADC_SENSOR_N), and the microcontroller can turn off the drive switch Q1 to prevent overcurrent faults.

[0084] An anti-backflow diode is provided between the sampling control unit and the voltage divider resistor unit. Please refer to [link / reference]. Figure 3 The anti-reverse current diode is D3. This diode ensures unidirectional conductivity from the sampling control unit to the voltage divider resistor unit and prevents current from flowing from the voltage divider resistor unit to the sampling control unit. The anti-reverse current diode prevents reverse breakdown voltage and forward voltage drop, ensuring circuit safety and normal operation.

[0085] The microcontroller unit also includes a processing logic unit, which can be used to determine the resistance value of the liquid level sensor by using the voltage divider and the resistance value of the voltage divider resistor unit.

[0086] In some possible embodiments, the resistance value of the liquid level sensor can be determined by the following execution process: acquiring the first pin voltage of the first pin and the second pin voltage of the second pin; determining the difference between the first pin voltage and the second pin voltage as the voltage divider voltage; determining the ratio of the voltage divider voltage to the resistance value of the voltage divider resistor unit as the circuit current; determining the ratio of the first pin voltage to the circuit current as the circuit resistance; and determining the difference between the circuit resistance and the resistance value of the voltage divider resistor unit as the resistance value of the liquid level sensor.

[0087] Please see Figure 3 When sampling the liquid level resistance is required, the drive switch Q1 is turned on, outputting a DC voltage. The voltage across the differential sampling voltage divider unit R1 is used to obtain the R1 current by dividing this voltage by the resistance of the voltage divider unit R1. The R1 current is actually the R8 current; therefore, the R8 resistance is equal to the pin voltage of the first pin Vp, divided by the R1 / R8 current, and then subtracted from the resistance of R1.

[0088] Figure 4 This is a schematic flowchart illustrating a resistance detection method provided in an embodiment of this application. Please refer to... Figure 4 The method may include:

[0089] S401. Send a sampling frequency control signal to the sampling control unit.

[0090] The execution entity in this application embodiment can be a microcontroller unit or a resistance determination device disposed in the microcontroller unit. The resistance determination device can be implemented by software or by a combination of software and hardware.

[0091] The sampling frequency control signal is used to indicate the sampling frequency of the resistance value of the liquid level sensor.

[0092] The sampling frequency control signal can be a sampling signal or a non-sampling signal. The sampling signal is used to control the drive switch that starts the sampling control unit, and the non-sampling signal is used to indicate the drive switch that stops the sampling control unit.

[0093] S402. If the sampling frequency control signal is a sampling signal, then determine the voltage divider of the voltage divider resistor unit.

[0094] The difference between the voltage at the first pin and the voltage at the second pin can be determined as the voltage divider.

[0095] S403. Determine the resistance value of the liquid level sensor based on the voltage divider and the resistance value of the voltage divider resistor unit.

[0096] For details on the specific execution process of S403, please refer to the execution process of the above embodiments, which will not be repeated here.

[0097] The resistance detection method provided in this application embodiment can control the detection of the resistance detection circuit through a sampling frequency control signal. When the sampling frequency control signal is a sampling signal, the resistance value of the liquid level sensor is detected. There is no need to continuously power on the liquid level sensor, which can improve the safety of the sensor.

[0098] Figure 5 This is a schematic diagram of a resistance detection device provided in an embodiment of this application. Please refer to... Figure 5 The device 500 may include a sending module 501, a first determining module 502, and a second determining module 503, wherein...

[0099] The transmitting module 501 is used to send a sampling frequency control signal to the sampling control unit;

[0100] The first determining module 502 is used to determine the voltage divider of the voltage divider resistor unit if the sampling frequency control signal is a sampling signal.

[0101] The second determining module 503 is used to determine the resistance value of the liquid level sensor based on the voltage divider and the resistance value of the voltage divider resistor unit.

[0102] The resistance detection device provided in this application embodiment can execute the technical solution shown in the above method embodiment. Its implementation principle and beneficial effects are similar, and will not be described again here.

[0103] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Please refer to... Figure 6 The electronic device 600 may include a processor 601 and a memory 602. Exemplarily, the processor 601 and the memory 602 are interconnected via a bus 603.

[0104] Memory 602 stores computer-executed instructions;

[0105] The processor 601 executes computer execution instructions stored in the memory 602, causing the processor 601 to perform the resistance detection method as shown in the above method embodiment.

[0106] Accordingly, this application provides an oil level detection system, which includes a resistance detection circuit and a liquid level sensor as described in the above embodiments, wherein the liquid level sensor is connected to the voltage divider resistor unit of the resistance detection circuit.

[0107] Accordingly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the resistance detection method of the above-described method embodiments.

[0108] Accordingly, embodiments of this application may also provide a computer program product, including a computer program, which, when executed by a processor, can implement the resistance detection method shown in the above method embodiments.

[0109] Those skilled in the art will understand that this embodiment can be provided as a method, system, or computer program product. Therefore, it can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this embodiment can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0110] It should be understood that each block of a flowchart and / or block diagram, and combinations of blocks in a flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0111] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0112] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0113] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0114] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0115] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0116] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0117] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A resistance detection circuit, characterized in that, The resistance detection circuit is located outside the fuel tank. The resistance detection circuit includes a sampling control unit, a voltage divider resistor unit, and a microcontroller unit. The sampling control unit is connected to a power supply and is connected to a first terminal of the voltage divider resistor unit. The second terminal of the voltage divider resistor unit is connected to a liquid level sensor. The microcontroller unit is connected to the voltage divider resistor unit and also to the sampling control unit. The voltage divider resistor unit is used to share the input voltage in the resistance detection circuit with the liquid level sensor; The microcontroller unit is used to control the detection of the resistance detection circuit to be turned on or off through the sampling control unit, and when the detection is turned on, to determine the resistance value of the liquid level sensor through the voltage divider of the voltage divider unit.

2. The circuit according to claim 1, characterized in that, The microcontroller unit is used to send a sampling frequency control signal to the sampling control unit; The sampling control unit is used to control the detection of the resistance detection circuit to be turned on or off according to the sampling frequency control signal.

3. The circuit according to claim 2, characterized in that, The sampling control unit includes a drive switch; The drive switch is activated if the sampling frequency control signal is a sampling signal, so as to control the detection of the resistance detection circuit. The drive switch is also used to turn off if the sampling frequency control signal is a non-sampling signal, so as to control the detection shutdown of the resistance detection circuit.

4. The circuit according to claim 3, characterized in that, The driving switch includes a gate, a drain, and a source. The gate is connected to the microcontroller unit, the drain is connected to the power supply, and the source is connected to the voltage divider resistor unit. The sampling control unit further includes a first resistor and a second resistor. The first resistor is disposed between the microcontroller and the gate, and the first resistor is used to limit the peak value of the drive current of the microcontroller. The second resistor is disposed between the gate and the drain, and is used to adjust the impedance between the gate and the drain to limit the reflection of the sampling frequency control signal.

5. The circuit according to claim 3, characterized in that, The microcontroller unit is equipped with a digital-to-analog converter. The first pin of the digital-to-analog converter is connected to one end of the voltage divider resistor unit, and the second pin of the digital-to-analog converter is connected to the other end of the voltage divider resistor unit. The first pin is used to detect the voltage at the first terminal of the voltage divider resistor unit, and the second pin is used to detect the voltage at the second terminal of the voltage divider resistor unit. The voltage divider voltage is the difference between the voltage at the first terminal and the voltage at the second terminal.

6. The circuit according to claim 5, characterized in that, The microcontroller unit further includes a processing logic unit, which is used to determine the resistance value of the liquid level sensor by using the voltage divider and the resistance value of the voltage divider resistor unit.

7. The circuit according to claim 6, characterized in that, A first protection unit is provided between the first pin and the voltage divider resistor unit, and a second protection unit is provided between the second pin and the voltage divider resistor unit. The first protection unit is used to protect the first port of the digital-to-analog converter connected to the first pin; The second protection unit is used to protect the second port of the digital-to-analog converter connected to the second pin.

8. The circuit according to claim 7, characterized in that, The microcontroller unit is also used to control the drive switch to turn off when it detects that the liquid level sensor is grounded via the second pin of the digital-to-analog converter.

9. The circuit according to claim 1, characterized in that, An anti-backflow diode is provided between the sampling control unit and the voltage divider resistor unit, wherein, The anti-backflow diode is used to conduct electricity unidirectionally from the sampling control unit to the voltage divider resistor unit and to prevent current from flowing from the voltage divider resistor unit to the sampling control unit.

10. An oil level detection system, the oil level detection system comprising a resistance detection circuit and a liquid level sensor as described in any one of claims 1-9, wherein the liquid level sensor is connected to a voltage divider resistor unit of the resistance detection circuit.

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