Resistance detection circuit and oil level detection system

Abstract

The embodiment of the invention provides a resistance detection circuit and an oil level detection system. The resistance detection circuit is located outside the fuel oil tank and comprises a sampling control unit, a divider resistance unit and a micro-control unit, the sampling control unit is connected with the power source and connected with the first end of the divider resistance unit, and the second end of the divider resistance unit is connected with the liquid level sensor; the micro-control unit is connected with the divider resistance unit, the micro-control unit is connected with the sampling control unit, and the divider resistance unit is used for sharing input voltage in the resistance detection circuit with the liquid level sensor; and the micro-control unit is used for controlling the detection starting or detection closing of the resistance detection circuit through the sampling control unit, and determining the resistance value of the liquid level sensor according to the divided voltage of the divider resistance unit when the detection starting is carried out. The method is used for achieving the effect of improving the use safety of the sensor.

Description

Technical Field

[0001] This application relates to the technical field of vehicles, and particularly to a resistance detection circuit and an oil level detection system. Background Art

[0002] The liquid level sensor in the fuel tank is generally a float type / resistance type sensor. The liquid level sensor can be based on the buoyancy principle, and the floating ball triggers the change of the resistance value as the liquid level rises and falls.

[0003] In the related art, the resistance detection circuit of the resistance type can inject a DC voltage with a voltage-dividing resistor into the liquid level sensor, detect the voltage across the liquid level sensor, and calculate the resistance value of the liquid level sensor according to the voltage division theorem. However, a current continuously passes through the liquid level sensor, generating power consumption, causing the sensor inside the fuel tank to heat up, and making the safety of using the sensor relatively low. Summary of the Invention

[0004] The embodiments of this application provide a resistance detection circuit and an oil level detection system to achieve the effect of improving the safety of using the sensor.

[0005] In a first aspect, the embodiments of this application provide a resistance detection circuit. The resistance detection circuit is located outside the fuel tank. The resistance detection circuit includes a sampling control unit, a voltage-dividing resistor unit, and a micro-control unit. The sampling control unit is connected to a power supply. The sampling control unit is connected to the first end of the voltage-dividing resistor unit. The second end of the voltage-dividing resistor unit is connected to a liquid level sensor. The micro-control unit is connected to the voltage-dividing resistor unit. The micro-control unit is connected to the sampling control unit. Among them,

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

[0007] The micro-control unit is configured to control the detection start or stop of the resistance detection circuit through the sampling control unit, and when the detection is started, determine the resistance value of the liquid level sensor through the divided voltage of the voltage-dividing resistor unit.

[0008] In a possible implementation manner, the micro-control unit is configured to send a sampling frequency control signal to the sampling control unit;

[0009] The sampling control unit is configured to control the detection start or stop of the resistance detection circuit according to the sampling frequency control signal.

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

[0011] The driving switch is used to start if the sampling frequency control signal is a sampling signal, so as to control the detection start of the resistance detection circuit;

[0012] The driving 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 a possible implementation manner, the driving switch includes a gate, a drain, and a source. The gate is connected to the micro-control unit, the drain is connected to the power supply, and the source is connected to the voltage dividing resistor unit. The sampling control unit further includes a first resistor and a second resistor, wherein,

[0014] The first resistor is arranged between the micro-control unit and the gate, and the first resistor is used to limit the peak value of the driving current of the micro-control unit;

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

[0016] In a possible implementation manner, the micro-control unit is provided with a digital-to-analog converter. A first pin corresponding to the digital-to-analog converter is connected to one end of the voltage dividing resistor unit, and a second pin corresponding to the digital-to-analog converter is connected to the other end of the voltage dividing resistor unit;

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

[0018] In a possible implementation manner, the micro-control unit further includes a processing logic unit, and the processing logic unit is used to determine the resistance value of the liquid level sensor according to the divided voltage and the resistance value of the voltage dividing resistor unit.

[0019] In a possible implementation manner, a first protection unit is arranged between the first pin and the voltage dividing resistor unit, and a second protection unit is arranged between the second pin and the voltage dividing 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 a possible implementation, the microcontroller unit is further configured to control the drive switch to turn off when it detects that the liquid level sensor is grounded through the second pin of the digital-to-analog converter.

[0023] In a possible implementation, an anti-backflow diode is provided between the sampling control unit and the voltage-dividing resistor unit, where

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

[0025] In a second aspect, an oil level detection system provided by an embodiment of the present application includes a resistance detection circuit and a liquid level sensor as described in the first aspect, and the liquid level sensor is connected to the voltage-dividing resistor unit of the resistance detection circuit.

[0026] In a third aspect, an embodiment of the present application provides a method for detecting a resistance, which is applied to the above-mentioned resistance detection circuit, and the method includes:

[0027] The microcontroller unit sends a sampling frequency control signal to the sampling control unit, and the sampling frequency control signal is used to indicate sampling the resistance value of the liquid level sensor at a preset frequency;

[0028] If the sampling frequency control signal is a sampling signal, determine the divided voltage of the voltage-dividing resistor unit;

[0029] Determine the resistance value of the liquid level sensor according to the divided voltage and the resistance value of the voltage-dividing resistor unit.

[0030] In a fourth aspect, an embodiment of the present application provides a device for detecting a resistance, and the device includes a sending module, a first determining module, and a second determining module, where

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

[0032] The first determining module is configured to determine the divided voltage of the voltage-dividing resistor unit if the sampling frequency control signal is a sampling signal;

[0033] The second determining module is configured to determine the resistance value of the liquid level sensor according to the divided voltage and the resistance value of the voltage-dividing resistor unit.

[0034] In a fifth aspect, an embodiment of the present application provides an electronic device, including: a memory, a processor;

[0035] The memory stores computer execution instructions;

[0036] The processor executes the computer-executable instructions stored in the memory, so that the processor executes the implementation manners of the third aspect as described above.

[0037] In a sixth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, they are used to implement the implementation manners of the third aspect as described above.

[0038] In a seventh aspect, an embodiment of the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the implementation manners of the third aspect as described above.

[0039] The resistance detection circuit and the oil level detection system provided by the embodiments of the present application, the resistance detection circuit is located outside the fuel tank, and the resistance detection circuit includes a sampling control unit, a voltage dividing resistor unit and a micro control unit. The voltage dividing resistor unit can be 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 start or detection off of the resistance detection circuit through the sampling control unit, and when the detection is started, determine the resistance value of the liquid level sensor through the divided voltage of the voltage dividing resistor unit. The micro control unit can control the detection of the resistance detection circuit through the sampling control unit, without continuously energizing the liquid level sensor, which can improve the safety of sensor use. Description of the Drawings

[0040] The drawings here are incorporated into the specification and constitute a part of this specification, showing the embodiments that conform to the present application, and are used together with the specification to explain the principles of the present application.

[0041] Figure 1 It is a schematic diagram of an application scenario provided by an embodiment of the present application;

[0042] Figure 2 It is a schematic structural diagram of a resistance detection circuit provided by an embodiment of the present application;

[0043] Figure 3 It is a schematic structural diagram of another resistance detection circuit provided by an embodiment of the present application;

[0044] Figure 4 It is a schematic flowchart of a method for detecting a resistance provided by an embodiment of the present application;

[0045] Figure 5 It is a schematic structural diagram of a device for detecting a resistance provided by an embodiment of the present application;

[0046] Figure 6 It is a schematic structural diagram of an electronic device provided by an embodiment of the present application.

[0047] Through the above-mentioned accompanying drawings, specific embodiments of the present application have been shown, and will be described in more detail hereinafter. These drawings and the written description are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by reference to specific embodiments. Detailed Description of the Embodiments

[0048] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0049] Figure 1 A schematic diagram of an application scenario provided for an embodiment of the present application. Please refer to Figure 1 , including a fuel tank 101, a liquid level sensor 102, and a resistance detection circuit 103 of a vehicle.

[0050] A liquid level sensor 102 can be placed in the fuel tank 101. The liquid level sensor can be a float sensor or a resistance sensor. A floating ball is provided in the liquid level sensor. Based on the buoyancy principle, the floating ball can rise and fall with the liquid level, triggering a change in the resistance value of the liquid level sensor. The resistance detection circuit 103 can be connected to the liquid level sensor 102 to detect the resistance value of the liquid level sensor 102, and determine the fuel liquid level in the fuel tank 101 according to the resistance value of the liquid level sensor 102.

[0051] In the prior art, a resistance type resistance detection circuit can inject a DC voltage with a voltage dividing resistor into the liquid level sensor, detect the voltage across the liquid level sensor, and calculate the resistance value of the liquid level sensor according to the voltage division theorem. However, a current will continuously pass through the liquid level sensor, generating power consumption, causing the sensor inside the fuel tank to heat up, and making the use of the sensor less safe.

[0052] The resistance detection circuit provided by the embodiment of the present application is located outside the fuel tank. The resistance detection circuit includes a sampling control unit, a voltage dividing resistor unit, and a micro control unit. The voltage dividing resistor unit can be 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 start or stop of the resistance detection circuit through the sampling control unit, and when the detection starts, determine the resistance value of the liquid level sensor through the divided voltage of the voltage dividing resistor unit. The micro control unit can control the detection of the resistance detection circuit through the sampling control unit, and there is no need to continuously supply power to the liquid level sensor, which can improve the safety of sensor use.

[0053] Figure 2 This is a schematic structural diagram of a resistance detection circuit provided by an embodiment of the present application. Please refer to Figure 2 , the resistance detection circuit includes a sampling control unit, a voltage dividing resistor unit, and a micro control unit. The sampling control unit is connected to a power supply. The sampling control unit is connected to the first end of the voltage dividing resistor unit. The second end of the voltage dividing resistor unit is connected to a liquid level sensor. The micro control unit is connected to the voltage dividing resistor unit, and the micro control unit is connected to the sampling control unit.

[0054] The resistance value of the liquid level sensor changes with the change of the fuel tank liquid level. When the fuel tank liquid level rises, the resistance value of the sensor decreases; when the fuel tank liquid level drops, the resistance value of the sensor increases.

[0055] When detecting the liquid level sensor through the resistance detection circuit, if the resistance of the liquid level sensor is large, the heat generated by the liquid level sensor is large, and 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] The voltage dividing resistor unit can be connected in series with the liquid level sensor. The voltage dividing resistor unit can be used to share the input voltage in the resistance detection circuit with the liquid level sensor, and can reduce the voltage of the liquid level sensor in the resistance detection circuit, so as to reduce the heat generated by the liquid level sensor when detecting the fuel tank liquid level.

[0057] The micro control unit is used to control the detection start or detection stop of the resistance detection circuit through the sampling control unit.

[0058] Specifically, the micro control unit can send a sampling frequency control signal to the sampling control unit, and the sampling control unit can control the detection start or detection stop of the resistance detection circuit according to 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 start of the resistance detection circuit, and the non-sampling signal is used to control the detection stop of the resistance detection circuit.

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

[0061] When the detection is started, the micro control unit can determine the resistance value of the liquid level sensor through the divided voltage of the voltage dividing resistor unit.

[0062] The voltage dividing resistor unit can be a high-precision resistor. The resistance detection circuit can measure the resistance of the voltage dividing resistor unit, and then 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 by the embodiment of the present application can send a sampling frequency control signal to the sampling control unit through a microcontroller unit to control the start and stop of the sampling control unit, so as to realize the detection of the resistance detection circuit. It is not necessary to continuously power on the liquid level sensor, which can improve the safety of sensor use.

[0064] Figure 3 It is a schematic structural diagram of another resistance detection circuit provided by the embodiment of the present application. Please refer to Figure 3 , the sampling control unit may include a driving switch, a first resistor, and a second resistor. The driving switch may include 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 other end of the power supply is grounded (Grounding, GND). The source is connected to the voltage dividing resistor unit. The first resistor is arranged between the microcontroller unit and the gate, and the second resistor is arranged between the gate and the drain.

[0065] If the sampling frequency control signal is a sampling signal, the driving switch is started to control the start of the detection of the resistance detection unit; if the sampling frequency control signal is a non-sampling signal, the driving switch is turned off to control the stop of the detection of the resistance detection unit.

[0066] The driving switch may be a controlled MOS switch. The controlled MOS switch can, based on the electric field effect control mechanism of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), adjust the formation and disappearance of the conductive channel through the gate voltage to achieve precise control of the on and off of the current.

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

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

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

[0070] The microcontroller unit is provided with an analog-to-digital converter (ADC). The analog-to-digital converter can convert continuously varying analog signals (such as voltage and current) into discrete digital signals (binary values) for the microcontroller unit to process and analyze.

[0071] The analog-to-digital 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 dividing resistor unit, and the second pin is connected to the other end of the voltage dividing resistor unit.

[0072] Please refer to Figure 3 , the voltage collected by the first pin (ADC_SENSOR_P) is the voltage at the positive end of the sensor, and the voltage collected by the second pin (ADC_SENSOR_N) is the voltage at the negative end of the sensor.

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

[0074] In the embodiments of the present application, by differentially sampling the voltage of the voltage dividing resistor unit, the ability to resist common-mode interference can be improved, and the sampling accuracy can be enhanced.

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

[0076] The first protection unit is used to protect the first port of the analog-to-digital converter connected to the first pin, and convert the voltage drop of the voltage dividing resistor unit into a voltage range suitable for the input of the analog-to-digital converter. Please refer to Figure 3 , the first protection unit includes resistor R2 and resistor R3. The resistance ratio of R2 and R3 determines the input voltage range of the analog-to-digital converter. Among them, resistor R3 is grounded.

[0077] Similarly, the second protection unit is used to protect the second port of the analog-to-digital converter connected to the second pin, and convert the voltage drop of the voltage dividing resistor unit into a voltage range suitable for the input of the analog-to-digital converter. Please refer to Figure 3 , the second protection unit includes resistor R4 and resistor R5. The resistance ratio of R4 and R5 determines the input voltage range of the analog-to-digital converter. Among them, resistor R5 is grounded.

[0078] The first protection unit and the second protection unit can play a role in protecting the hydraulic sensor. Taking the first protection unit as an example, when the resistance value of the hydraulic sensor is too low, if the resistance value of the first protection unit is too small, it may cause the current at both ends of the hydraulic sensor to be too large, thus damaging the hydraulic sensor. Therefore, the resistance value of the first protection unit should be much larger than that of the hydraulic sensor to limit the current at both ends of the hydraulic sensor.

[0079] On the other hand, the sum of the resistance values of the first protection unit is much larger than the resistance value of the hydraulic sensor, and the sum of the resistance values of the second protection unit is much larger than the resistance value of the hydraulic sensor, which can ensure that the voltage drop at both ends of the sensor can accurately reflect the change in the resistance value of the hydraulic sensor, thereby improving the measurement accuracy.

[0080] Taking the first protection unit as an example, when the resistance value of the first protection unit is much larger than that of the hydraulic sensor, the voltage drop at both ends of the hydraulic sensor will be mainly determined by the resistance value of the hydraulic sensor, and the influence of the change in the resistance value of the first protection unit on the voltage drop at both ends of the hydraulic sensor can be ignored. Therefore, the voltage signal collected by the analog-to-digital converter will more accurately reflect the change in the resistance value of the hydraulic sensor, thereby improving the measurement accuracy.

[0081] For example, when the signal of the hydraulic sensor is short-circuited to the vehicle's battery, through the first protection unit and the second protection unit, it is possible to prevent backflow and breakdown of the port of the analog-to-digital converter.

[0082] The micro control unit is also used to control the drive switch to close when it detects that the liquid level sensor is grounded through the second pin of the analog-to-digital converter.

[0083] For example, please refer to Figure 3 , when the signal of the hydraulic sensor is short-circuited to the ground GND, it can be detected by the second pin (ADC_SENSOR_N), and the micro control unit can close the drive switch Q1 to prevent overcurrent faults.

[0084] An anti-backflow diode is provided between the sampling control unit and the voltage dividing resistor unit. Please refer to Figure 3 , the anti-backflow diode is D3. The anti-backflow diode is used to conduct unidirectionally from the sampling control unit to the voltage dividing resistor unit and prevent current from flowing from the voltage dividing resistor unit to the sampling control unit. The anti-backflow diode can prevent reverse breakdown voltage and forward voltage drop, and can ensure the safety and normal operation of the circuit.

[0085] The micro control unit also includes a processing logic unit, which can be used to determine the resistance value of the liquid level sensor based on the divided voltage and the resistance value of the voltage dividing resistor unit.

[0086] In some possible embodiments, the following execution process can be referred to for determining the resistance value of the liquid level sensor: Obtain the first pin voltage of the first pin and the second pin voltage of the second pin; Determine the divided voltage as the difference between the first pin voltage and the second pin voltage; Determine the circuit current as the ratio of the divided voltage to the resistance value of the voltage dividing resistor unit; Determine the circuit resistance as the ratio of the first pin voltage to the circuit current; Determine the resistance value of the liquid level sensor as the difference between the circuit resistance and the resistance value of the voltage dividing resistor unit.

[0087] Please refer to Figure 3 , when sampling the liquid level resistance, turn on the driving switch Q1 to output a DC voltage. Sample the divided voltage across both ends of the voltage dividing resistor unit R1 through differential sampling. The divided voltage divided by the resistance value of the voltage dividing resistor unit R1 gives the R1 current. The R1 current is actually also the R8 current. Therefore, the R8 resistance value is equal to the pin voltage of the first pin Vp divided by the R1 / R8 current, and then subtract the resistance of R1.

[0088] Figure 4 It is a schematic flow chart of a method for detecting the resistance provided by an embodiment of the present 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 subject of the embodiment of the present application can be a microcontroller unit or a resistance determination device provided 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 sampling the resistance value of the liquid level sensor at a preset frequency.

[0092] The sampling frequency control signal can be a sampling signal and a non-sampling signal. The sampling signal is used to control the driving switch of the sampling control unit to start, and the non-sampling signal is used to indicate closing the driving switch of the sampling control unit.

[0093] S402: If the sampling frequency control signal is a sampling signal, determine the divided voltage of the voltage dividing resistor unit.

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

[0095] S403: Determine the resistance value of the liquid level sensor according to the divided voltage and the resistance value of the voltage dividing resistor unit.

[0096] For the specific execution process of S403, please refer to the execution process of the above embodiment, which will not be elaborated here.

[0097] The resistance detection method provided by the embodiment of the present application 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, and there is no need to continuously power on the liquid level sensor, which can improve the safety of sensor use.

[0098] Figure 5 It is a schematic structural diagram of a resistance detection device provided by the embodiment of the present application. Please refer to Figure 5 The device 500 may include a sending module 501, a first determination module 502, and a second determination module 503, where

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

[0100] The first determination module 502 is configured to determine the divided voltage of the voltage dividing resistor unit if the sampling frequency control signal is a sampling signal;

[0101] The second determination module 503 is configured to determine the resistance value of the liquid level sensor according to the divided voltage and the resistance value of the voltage dividing resistor unit.

[0102] The resistance detection device provided by the embodiment of the present application can execute the technical solution shown in the above method embodiment, and its implementation principle and beneficial effects are similar, so details will not be described here.

[0103] Figure 6 It is a schematic structural diagram of an electronic device provided by the embodiment of the present 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 with each other through a bus 603.

[0104] The memory 602 stores computer execution instructions;

[0105] The processor 601 executes the computer execution instructions stored in the memory 602, so that the processor 601 executes the resistance detection method shown in the above method embodiment.

[0106] Correspondingly, the embodiment of the present application provides an oil level detection system, which includes a resistance detection circuit and a liquid level sensor as described in the above embodiment, and the liquid level sensor is connected to the voltage dividing resistor unit of the resistance detection circuit.

[0107] Correspondingly, the embodiment of the present application provides a computer-readable storage medium, in which computer execution instructions are stored, and when the computer execution instructions are executed by a processor, they are used to implement the resistance detection method in the above method embodiment.

[0108] Correspondingly, an embodiment of the present application can 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 embodiment.

[0109] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can adopt the form of an all-hardware embodiment, an all-software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can adopt 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] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the specified functions in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0111] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the specified functions in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0112] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the specified functions in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

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

[0114] Memory may include non - permanent memory in the form of computer - readable media, 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 by any method or technology. The information can be computer - readable instructions, data structures, program modules, 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, compact disc read - only memory (CD - ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic disk storage or other magnetic storage devices, or any other non - transitory media that can be used to store information accessible by a computing device. As defined herein, computer - readable media does not include transitory computer - readable media such as modulated data signals and carrier waves.

[0116] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, such that a process, method, article or apparatus that comprises a series of elements includes not only those elements but also other elements not expressly listed, or elements that are inherent to such process, method, article or apparatus. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or apparatus that comprises the element.

[0117] The above are only embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present 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 dividing resistor unit, and a micro control unit. The sampling control unit is connected to a power supply. The sampling control unit is connected to the first end of the voltage dividing resistor unit. The second end of the voltage dividing resistor unit is connected to a liquid level sensor. The micro control unit is connected to the voltage dividing resistor unit and the micro control unit is connected to the sampling control unit. Among them, the voltage dividing resistor unit is configured to share the input voltage in the resistance detection circuit with the liquid level sensor; the micro control unit is configured to control the detection start or detection stop of the resistance detection circuit through the sampling control unit, and when the detection is started, determine the resistance value of the liquid level sensor through the divided voltage of the voltage dividing resistor unit.

2. The circuit according to claim 1, wherein the micro control unit is configured to send a sampling frequency control signal to the sampling control unit; the sampling control unit is configured to control the detection start or detection stop of the resistance detection circuit according to the sampling frequency control signal.

3. The circuit according to claim 2, wherein The sampling control unit includes a driving switch; the driving switch is configured to start if the sampling frequency control signal is a sampling signal, so as to control the detection start of the resistance detection circuit; the driving switch is further configured to turn off if the sampling frequency control signal is a non-sampling signal, so as to control the detection stop 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 micro control unit. The drain is connected to the power supply. The source is connected to the voltage dividing resistor unit. The sampling control unit further includes a first resistor and a second resistor. Among them, the first resistor is arranged between the micro control unit and the gate. The first resistor is used to limit the peak value of the driving current of the micro control unit; the second resistor is arranged between the gate and the drain. The second resistor 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, wherein the micro control unit is provided with a digital-to-analog converter. The first pin corresponding to the digital-to-analog converter is connected to one end of the voltage dividing resistor unit. The second pin corresponding to the digital-to-analog converter is connected to the other end of the voltage dividing resistor unit; the first pin is used to detect the voltage at the first end of the voltage dividing resistor unit. The second pin is used to detect the voltage at the second end of the voltage dividing resistor unit. The divided voltage is the difference between the voltage at the first end and the voltage at the second end.

6. The circuit according to claim 5, wherein The micro control unit further includes a processing logic unit. The processing logic unit is configured to determine the resistance value of the liquid level sensor through the divided voltage and the resistance value of the voltage dividing resistor unit.

7. The circuit according to claim 6, characterized in that, A first protection unit is arranged between the first pin and the voltage dividing resistor unit. A second protection unit is arranged between the second pin and the voltage dividing resistor unit. Among them, 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 configured to protect the second port of the digital-to-analog converter connected to the second pin.

8. The circuit according to claim 1, wherein An anti-backflow diode is provided between the sampling control unit and the voltage-dividing resistor unit, where the anti-backflow diode is configured to conduct unidirectionally from the sampling control unit to the voltage-dividing resistor unit and prevent current from flowing from the voltage-dividing resistor unit to the sampling control unit.

9. An oil level detection system, characterized in that, The oil level detection system includes the resistance detection circuit and the liquid level sensor as described in claims 1-8, and the liquid level sensor is connected to the voltage-dividing resistor unit of the resistance detection circuit.

10. A method for detecting a resistor, characterized in that, The method is applied to the circuit as described in any one of claims 1-8, and the method includes: The micro control unit sends a sampling frequency control signal to the sampling control unit, and the sampling frequency control signal is used to indicate sampling the resistance value of the liquid level sensor at a preset frequency; If the sampling frequency control signal is a sampling signal, determine the divided voltage of the voltage-dividing resistor unit; Determine the resistance value of the liquid level sensor according to the divided voltage and the resistance value of the voltage-dividing resistor unit.

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