Proximity sensor with normally closed switch structure and automobile electric pedal control circuit

Abstract

The application relates to the technical field of vehicle accessories, and provides a proximity sensor and a control circuit of an automobile electric pedal which replace the structure of a normally closed switch. The proximity sensor comprises a PCB board, a normally open dry reed SW and a normally closed switch equivalent circuit; the normally closed switch equivalent circuit is connected with a power supply VCC and the normally open dry reed SW through a diode D1 and an upper pull resistor R2 to form a product anode, and a grounding end forms a product cathode. When there is no trigger magnetic field, the normally open dry reed SW is disconnected, and the normally closed switch equivalent circuit is equivalent to a normally closed switch closed state; when there is a trigger magnetic field, the normally open dry reed SW is attracted and turned on, and the normally closed switch equivalent circuit is equivalent to a normally closed switch open state. The normally open dry reed and the normally closed switch equivalent circuit replace the traditional normally closed dry reed, no mechanical stress and current pass through in a normal state, effectively solve the problems of contact oxidation, metal fatigue and mechanical wear, meet the fault safety principle, and ensure the accuracy and reliability of the electric pedal control in the complex vehicle-mounted environment.

Description

Technical Field

[0001] This invention relates to the technical fields of vehicle accessories or vehicle components, signal detection, etc., specifically to a proximity sensor for electric car pedals, and more particularly to a proximity sensor and electric car pedal control circuit that replaces a normally closed switch structure. Background Technology

[0002] Automotive electric pedals rely on proximity sensors to identify when the pedal is fully extended and fully retracted. The vehicle controller uses a normally closed detection circuit as a safety fault mode: when there is no trigger magnetic field, the sensor circuit is closed, and the controller identifies the pedal as not fully extended; when a magnet approaches the trigger sensor, the circuit is opened, the controller identifies the pedal as extended and stops the motor. Currently, there are only two mainstream structures for proximity sensors that implement normally closed detection logic, both of which have reliability defects in mass production and under in-vehicle conditions, as detailed below: The first approach uses a 3-pin normally closed reed switch to form the detection circuit, where the reed switch contacts remain closed under normal conditions. This structure has several drawbacks: First, the contacts are constantly under pressure and mechanical stress, compounded by the impact of each magnetic field trigger. This leads to fatigue of the metal reed and oxidation of the contacts, shortening the lifespan compared to a normally open reed switch. It also makes poor contact and signal jitter highly likely during use. Second, the failure risk is extremely high. If several reed switch glass tubes rupture, the reeds fracture due to fatigue, or high-temperature corrosion causes permanent contact disconnection, the vehicle controller may misinterpret it as a normal closed state without a magnetic field, preventing the system from stopping after the pedal is in position, posing a collision or jamming safety hazard. Third, it is highly sensitive to stray magnetic fields, vehicle vibration, and ambient temperature drift. Under normal operating conditions, the contacts are prone to accidental disconnection, causing false pedal triggering and loss of control.

[0003] The second approach uses a normally open reed switch and adds a built-in permanent magnet inside the sensor housing. The built-in magnet continuously attracts the normally open reed switch, simulating a normally closed switch logic. However, this approach has more significant drawbacks: the built-in magnet only provides a critical magnetic field margin for engagement; slight vehicle vibrations, housing deformation, increased ambient temperature, and magnet misalignment can all cause the reed switch to momentarily disconnect, frequently resulting in erroneous pedal start / stop. Furthermore, the permanent magnet will gradually demagnetize under long-term exposure to high temperatures, vibrations, and reverse electromagnetic interference in the vehicle environment. Once the magnetic force weakens, it will be unable to maintain the reed switch's engagement, leading to permanent sensor failure. The assembly tolerances for the distance and angle between the magnet and the reed switch are stringent, resulting in poor consistency in automated batch assembly, low product yield, and the need for manual adjustment of each unit, leading to high mass production costs. Additionally, stray magnetic fields generated by inductors in the vehicle's circuit board, high-current wiring harnesses, and metal body components can superimpose or counteract these magnetic fields. The built-in magnet's magnetic field is eliminated, causing random jumps in the sensor signal logic. The normally open reed switch is designed to be normally disconnected with no mechanical loss. This solution forces it to be constantly engaged, causing continuous pressure oxidation of the contacts, metal fatigue, and lifespan degradation issues similar to the pure normally closed reed switch solution. Temperature changes will synchronously alter the permanent magnet's magnetic force and the reed switch's AT value, making it prone to loss of engagement at high temperatures and overly sensitive at low temperatures, resulting in poor adaptability to various operating conditions. Additional magnet mounting slots and fixing structures are required, increasing the overall product size and structural complexity, and raising material and processing costs compared to the pure normally closed reed switch solution. Relying on magnetic critical engagement without a clear mechanical travel boundary makes it impossible to achieve high-precision pedal limit detection.

[0004] In summary, neither of the existing two normally closed logic proximity sensors can maintain reliable circuit switching under mass production in vehicles and complex vibration and temperature change conditions. Frequent failures such as electric pedal not moving, not stopping when in position, and false triggering occur. The industry urgently needs a proximity sensor structure that is highly reliable, long-life, and anti-interference. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a proximity sensor and automotive electric pedal control circuit that replaces the normally closed switch structure, thereby achieving high reliability, long lifespan, and anti-interference capabilities for the sensor.

[0006] In a first aspect, the present invention provides a proximity sensor that replaces a normally closed switch structure, comprising a PCB board fixedly disposed inside a plastic housing, wherein a proximity sensor circuit is disposed on the PCB board, the proximity sensor circuit comprising: Normally open reed switch SW is soldered onto the PCB board; The normally closed switch equivalent circuit is set on the PCB board. The normally closed switch equivalent circuit is connected to the power supply VCC through a diode D1 and a pull-up resistor R2, and is connected to the normally open reed switch SW to form the positive terminal of the proximity sensor. The normally closed switch equivalent circuit is grounded to form the negative terminal of the proximity sensor. When no triggering magnetic field is generated, the normally open reed switch SW remains open, and the equivalent circuit of the normally closed switch is in the closed state; when the triggering magnetic field is generated, the normally open reed switch SW is attracted and conducts, and the equivalent circuit of the normally closed switch is in the open state.

[0007] Furthermore, the equivalent circuit of the normally closed switch includes a first resistor R1 and a switching transistor Q1. One end of the first resistor R1 is connected to ground along with the ground terminal of the switching transistor Q1, forming the negative terminal of the product. The other end of the first resistor R1 is connected to the control terminal of the switching transistor Q1 and one end of the normally open reed switch SW. The other end of the normally open reed switch SW is connected to the power supply terminal of the switching transistor Q1 and the cathode of the diode D1, forming the positive terminal of the product. The anode of the diode D1 is connected to the power supply VCC through a pull-up resistor R2. Under normal conditions, the normally open reed switch SW is open, and the switching transistor Q1 is forward biased and saturated through the first resistor R1, pulling the positive terminal of the product to a low level, effectively realizing the closing function of the normally closed switch. This process uses the switching characteristics of semiconductor devices to replace mechanical contacts, eliminating mechanical wear, providing almost unlimited operating life, and resulting in a simple control circuit structure that requires only a few discrete components, effectively reducing system complexity and potential failure points. The normally closed switch equivalent circuit converts the physical on / off action of the reed switch into a clear low-level and high-level signal at the positive terminal of the product through the conduction and cutoff of the switching transistor Q1. This provides the vehicle controller with a clear, jitter-free digital logic signal, which facilitates the controller's accurate identification of the pedal status and avoids misjudgments that may occur with analog signals.

[0008] Furthermore, the switching transistor Q1 is a PNP transistor, specifically an automotive-grade PNP transistor. The selection of an automotive-grade PNP transistor ensures that the device's key parameters, such as amplification, leakage current, and switching speed, remain stable under harsh conditions required by automotive electronics, including a wide temperature range (e.g., -40℃ to 125℃), strong vibration, and high humidity. This guarantees the consistent performance of the entire sensor throughout its lifespan.

[0009] Furthermore, when no triggering magnetic field is generated, the normally open reed switch SW remains open, the base of the PNP transistor receives a forward bias voltage through the first resistor R1 and is saturated and conducting. The positive terminal of the product is connected to ground through the conducting transistor, and the equivalent circuit of the normally closed switch is equivalent to the normally closed switch being closed. When a triggering magnetic field is generated, the normally open reed switch SW is energized and conducts, the base of the PNP transistor is shorted to the emitter through the normally open reed switch SW, the PNP transistor loses its forward bias and is cut off, the positive terminal of the product is only connected to the power supply VCC through the pull-up resistor, and the equivalent circuit of the normally closed switch is equivalent to the normally closed switch being open. In the absence of a triggering magnetic field, the PNP transistor receives a stable bias through the first resistor R1 and is deeply saturated and conducting, with an extremely low on-state voltage drop, which can be considered a reliable closed state. When the trigger magnetic field is generated, the normally open reed switch SW is attracted, shorting the base and emitter of the PNP transistor, causing it to quickly enter the cutoff state. The positive terminal of the product is only connected to the power supply VCC through diode D1 and pull-up resistor R2, forming a high-level disconnect state. This process involves rapid switching and a clear state. Under normal conditions (no magnetic field), the transistor is saturated and conducting, resulting in extremely low power consumption, which is suitable for the low static power consumption requirements of automotive battery power supply systems.

[0010] Furthermore, the first resistor R1 is an automotive-grade resistor. By limiting the first resistor R1 to an automotive-grade resistor, in conjunction with an automotive-grade transistor, the stability and reliability of the bias circuit can be guaranteed. This ensures that the bias voltage and current provided to the PNP transistor remain constant when the temperature changes, preventing the transistor's operating point from drifting and ensuring the accuracy of the state switching logic.

[0011] Furthermore, the pull-up resistor R2 is 10kΩ. Limiting the pull-up resistor R2 to 10kΩ provides sufficient pull-up drive capability, effectively limits the loop current, and serves as a current-limiting protection function.

[0012] Furthermore, the proximity sensor, which replaces the normally closed switch structure, also includes an external wire. One end of the external wire is soldered to the PCB board and connected to the negative and positive terminals of the product, respectively. The other end of the external wire extends outside the plastic housing. By setting the external wire, the internal circuitry of the sensor can be electrically connected to the external vehicle controller. The structure is simple and easy to arrange and install in space-constrained scenarios such as electric pedals in automobiles.

[0013] Furthermore, the plastic outer shell is a plastic box, and the inside of the plastic box has a positioning structure for the PCB board. After the PCB board is placed into the plastic box through the positioning structure, it is sealed and cured as a whole by potting epoxy resin. Specifically, encapsulating the PCB board and all electronic components in the plastic box and potting it with epoxy resin completely isolates the entire circuit module from the outside environment, achieving excellent dustproof, waterproof, moisture-proof, salt spray resistance, and chemical corrosion resistance. The protection level meets the requirements for use in harsh environments such as automotive chassis. After the epoxy resin potting and curing, the PCB board, components, and connecting wire harnesses are fixed into a robust whole, eliminating relative displacement and resonance between components, improving the product's ability to resist continuous vibration and road impact during vehicle operation, preventing solder joint fatigue fracture and component damage, and ensuring long-term operational reliability.

[0014] Secondly, this invention provides a control circuit for an electric vehicle pedal, including the aforementioned proximity sensor circuit, capacitor C1, diode D1, pull-up resistor R2, resistor R3, capacitor C2, and a vehicle controller. One end of capacitor C1 is grounded, and the other end is connected to the positive terminal of the proximity sensor and the cathode of diode D1. The anode of diode D1 is connected to the power supply VCC through pull-up resistor R2 and to one end of capacitor C2 and the I / O detection port of the vehicle controller through resistor R3. The other end of capacitor C2 is grounded. The vehicle controller identifies the position status of the electric vehicle pedal based on the high or low level of the I / O detection port and controls the motor to start and stop. Specifically, the vehicle controller acquires the level signal of the positive terminal of the sensor through the I / O detection port and accurately determines the fully retracted or fully extended state of the electric pedal based on a low level (equivalent to closed) and a high level (equivalent to open). Due to the use of the aforementioned highly reliable proximity sensor, the entire control system can fundamentally solve faults such as pedal malfunction or failure due to sensor mis-triggering, non-triggering, or malfunction, ensuring the functional safety and service life of the electric pedal system. When the sensor circuit experiences abnormalities such as open circuit or component damage, the positive terminal of the product will be pulled high by the pull-up resistor R2. The vehicle controller will recognize this as an open state, i.e., the pedal is in position, thereby stopping the motor and avoiding the risk of pedal loss of control, which meets the design requirements for automotive functional safety.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: This invention provides a proximity sensor and automotive electric pedal control circuit that replaces the normally closed switch structure. The proximity sensor includes a PCB board fixed inside a plastic housing. A proximity sensor circuit is disposed on the PCB board, comprising: a normally open reed switch SW soldered to the PCB board; and a normally closed switch equivalent circuit disposed on the PCB board. The normally closed switch equivalent circuit is connected to the power supply VCC through a diode D1 and a pull-up resistor R2, and is connected to the normally open reed switch SW to form the positive terminal of the proximity sensor. The normally closed switch equivalent circuit is grounded to form the negative terminal of the proximity sensor. When no trigger magnetic field is generated, the normally open reed switch SW remains open, and the normally closed switch equivalent circuit is equivalent to a closed normally closed switch. When a trigger magnetic field is generated, the normally open reed switch SW is attracted and conducts, and the normally closed switch equivalent circuit is equivalent to an open normally closed switch. This invention uses a normally open reed switch as the sensing element, combined with a normally closed switch equivalent circuit. Under normal conditions without a triggering magnetic field, the reed switch contacts remain open, with no mechanical stress or current flow. This fundamentally avoids the contact oxidation, metal fatigue, and mechanical wear problems caused by long-term pressure closure of traditional normally closed reed switches, resulting in a significantly longer service life compared to normally closed reed switch solutions. It effectively solves the problems of poor contact and signal jitter caused by contact aging in existing technologies. In this invention, the normally open reed switch is open under normal conditions, and its failure mode is permanent disconnection. At this time, the normally closed switch equivalent circuit will not be able to maintain an equivalent closed state, and the system can immediately detect the abnormality. This conforms to the design principle of "fault-based safety" and prevents safety accidents such as the electric pedal not stopping when it reaches its position due to sensor failure. This invention does not rely on a built-in permanent magnet to maintain the engaged state, avoiding problems such as instantaneous disconnection of the reed switch and signal logic jump caused by vibration, temperature drift, demagnetization of the permanent magnet or interference from stray magnetic fields in existing simulated normally closed schemes. It can maintain a stable equivalent normally closed state in complex vehicle vibration, wide temperature and strong electromagnetic interference environments, ensuring the accuracy of electric pedal control. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. Some specific embodiments of the invention will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings designate the same or similar parts or components. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a circuit diagram of a proximity sensor circuit in a proximity sensor that replaces the normally closed switch structure according to an embodiment of the present invention; Figure 2 This is a circuit diagram of an automotive electric pedal control circuit according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the proximity sensor that replaces the normally closed switch structure in an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Plastic outer shell; 2. PCB board; 3. Normally open reed switch SW; 4. PNP transistor; 5. First resistor R1; 6. External electrical wires. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] Example 1

[0020] Reference Figures 1-3 This embodiment provides a proximity sensor that replaces the normally closed switch structure. Through innovative circuit design, it uses a normally open reed switch and discrete components to form an equivalent circuit of a normally closed switch, which simulates and replaces the function of the traditional mechanical normally closed reed switch. This fundamentally solves the problems of short lifespan, poor reliability, and easy false triggering caused by long-term contact pressure, oxidation, and metal fatigue in traditional solutions.

[0021] The proximity sensor in this embodiment includes: a plastic housing and a PCB board fixed inside the plastic housing. The PCB board is provided with a proximity sensor circuit, which includes: a normally open reed switch SW and a normally closed switch equivalent circuit.

[0022] The plastic casing is a box with an internal positioning structure for securing the PCB board. After the PCB board is precisely inserted into the box via this positioning structure, the entire assembly is sealed and cured with epoxy resin. This encapsulation method completely isolates the PCB board and all electronic components from the external environment, providing excellent dustproof, waterproof, moisture-proof, salt spray resistance, and chemical corrosion resistance. The protection level meets the requirements for use in harsh environments such as automotive chassis. Simultaneously, the robust integral structure formed after epoxy resin curing effectively eliminates relative displacement and resonance between components, significantly improving the product's ability to withstand continuous vibration and road impacts during vehicle operation, preventing solder joint fatigue fracture and component damage, and ensuring long-term reliability.

[0023] The normally open reed switch SW is soldered onto the PCB board as a sensitive element for sensing external magnetic fields. When there is no external trigger magnetic field, its internal contacts remain normally open; when an external magnet approaches and reaches its action threshold, its internal contacts close and conduct.

[0024] The equivalent circuit of the normally closed switch is mounted on the PCB board. This circuit is connected to the power supply VCC through a diode D1 and a pull-up resistor R2, and the cathode of diode D1 forms the positive terminal of the entire proximity sensor. This positive terminal is also connected to one end of the normally open reed switch SW. The other end of the equivalent circuit is grounded, forming the negative terminal of the proximity sensor. The operating logic of this circuit is as follows: when no trigger magnetic field is generated, the normally open reed switch SW remains open, and the equivalent circuit of the normally closed switch is in a conducting state, equivalent to the closed state of a normally closed switch; when a trigger magnetic field is generated, the normally open reed switch SW is energized, and the equivalent circuit of the normally closed switch is in an open state, equivalent to the open state of a normally closed switch. Through this inverted logic conversion, the function of a normally closed switch is successfully implemented using a highly reliable normally open reed switch.

[0025] Specifically, the normally closed switch equivalent circuit in this embodiment includes a first resistor R1 and a switching transistor Q1. The switching transistor Q1 is preferably a PNP transistor, and specifically an automotive-grade transistor, to meet the high reliability requirements of automotive electronics under harsh conditions such as wide temperature ranges and strong vibrations. The first resistor R1 is also preferably an automotive-grade resistor to ensure the stability of the bias circuit. The specific circuit connections are as follows: one end of the first resistor R1 is connected to ground along with the emitter of the PNP transistor Q1, forming the negative terminal of the product; the other end of the first resistor R1 is connected to the base of the PNP transistor Q1 and one end of the normally open reed switch SW. The other end of the normally open reed switch SW is connected to the collector of the PNP transistor Q1 and the cathode of the diode D1, forming the positive terminal of the product. The anode of the diode D1 is connected to the power supply VCC through a pull-up resistor R2. The resistance value of the pull-up resistor R2 is preferably 10kΩ. This resistance value provides sufficient pull-up drive capability to ensure clear signal while effectively limiting the loop current, thus providing current limiting protection.

[0026] The circuit operation process of this embodiment is described in detail below: I. Normal working state (no triggering magnetic field) When the electric pedal is in the middle of retracting or extending, or when the magnet is away from the sensor, without external magnetic field triggering, the normally open reed switch SW remains in its inherent open state. At this time, the power supply VCC forms a path through diode D1, pull-up resistor R2, and first resistor R1, providing a forward bias voltage to the base of PNP transistor Q1. This bias voltage causes PNP transistor Q1 to enter a deep saturation conduction state. Due to the transistor's saturation conduction, there is an extremely low impedance between its collector and emitter, equivalent to a closed switch. At this time, the positive terminal of the product is directly connected to the negative terminal (system ground) through the conducting transistor Q1, and the potential of the positive terminal is pulled down to near ground level, i.e., a low level. This low-level state is equivalent to the closed state of a traditional normally closed switch, sending a clear non-position or running signal to the vehicle controller. In this state, the circuit power consumption is extremely low because the transistor is in a saturation conduction state, and its voltage drop is minimal, suitable for the low static power consumption requirements of automotive battery power supply systems.

[0027] II. Triggered Working State (with Trigger Magnetic Field) When the electric pedal of the car is moved to its fully retracted or fully extended limit position, the magnet mounted on the pedal mechanism approaches the proximity sensor, generating a trigger magnetic field. Under the action of this magnetic field, the internal contacts of the normally open reed switch SW close and conduct. The conduction of the reed switch shorts the base and emitter of the PNP transistor Q1, forcibly pulling the bias voltage of the base down to zero potential. The emitter junction of the PNP transistor Q1 immediately enters the cutoff state due to the loss of forward bias voltage. At this time, there is an extremely high impedance between the collector and emitter of the transistor Q1, which is equivalent to an open switch, cutting off the low-resistance path from the positive terminal to ground. The positive terminal of the product is only connected to the power supply VCC through diode D1 and pull-up resistor R2, and its potential is pulled up to a high level. This high-level state is equivalent to the open state of a traditional normally closed switch, sending a clear signal of arrival to the vehicle controller, which then stops the motor operation.

[0028] This circuit design converts the physical on / off action of the reed switch into clear, jitter-free low- and high-level digital logic signals on the positive terminal of the product through the conduction and cutoff of a transistor. This facilitates accurate identification of the pedal status by the vehicle controller, avoiding potential misjudgments caused by analog signals. Simultaneously, the design possesses fail-safe characteristics: when an anomaly occurs in the sensor circuit, such as a broken wire or component damage, the positive terminal of the product will be pulled high by the pull-up resistor R2. The vehicle controller will recognize this as an open state, i.e., the pedal is in position, thereby stopping the motor operation and preventing the risk of pedal malfunction, thus meeting the design requirements for automotive functional safety.

[0029] Furthermore, the proximity sensor in this embodiment also includes an external wire. One end of the external wire is soldered to the PCB board and connected to the positive and negative terminals of the product, respectively, while the other end extends out of the plastic housing for easy connection to the external vehicle controller wiring harness. The structure is simple and easy to arrange and install in space-constrained automotive electric pedal scenarios.

[0030] Example 2

[0031] See Figures 1-3 This embodiment provides a control circuit for an electric pedal in an automobile. This control circuit uses a proximity sensor that replaces the normally closed switch structure as described in Embodiment 1 and its equivalents.

[0032] The electric pedal control circuit includes the proximity sensor circuit, capacitor C1, diode D1, pull-up resistor R2, resistor R3, capacitor C2, and vehicle controller as described in the above embodiment. One end of capacitor C1 is grounded, and the other end is connected to the positive terminal of the proximity sensor and the cathode of diode D1. The anode of diode D1 is connected to the power supply VCC through pull-up resistor R2 and to one end of capacitor C2 and the IO detection port of the vehicle controller through resistor R3. The other end of capacitor C2 is grounded. The vehicle controller identifies the electric pedal's position status based on the high or low level of the IO detection port and controls the motor to start and stop. Specifically, the vehicle controller acquires the level signal of the positive terminal of the sensor through the IO detection port and accurately determines the fully retracted or fully extended state of the electric pedal based on a low level (equivalent to closed) and a high level (equivalent to open). Due to the use of the aforementioned highly reliable proximity sensor, the entire control system can fundamentally solve faults such as pedal not moving or not stopping when in position caused by sensor mis-triggering, non-triggering, or failure, ensuring the functional safety and service life of the electric pedal system. When the sensor circuit experiences abnormalities such as open circuit or component damage, the positive terminal of the product will be pulled high by the pull-up resistor R2. The vehicle controller will recognize this as an open state, i.e., the pedal is in position, thereby stopping the motor and avoiding the risk of pedal loss of control, which meets the design requirements for automotive functional safety.

[0033] It should be noted that the above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention, and the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A proximity sensor that replaces a normally closed switch structure, comprising a PCB board fixed inside a plastic housing, wherein a proximity sensor circuit is disposed on the PCB board, characterized in that, The proximity sensor circuit includes: Normally open reed switch SW is soldered onto the PCB board; The normally closed switch equivalent circuit is set on the PCB board. The normally closed switch equivalent circuit is connected to the power supply VCC through a diode D1 and a pull-up resistor R2, and is connected to the normally open reed switch SW to form the positive terminal of the proximity sensor. The normally closed switch equivalent circuit is grounded to form the negative terminal of the proximity sensor. When no triggering magnetic field is generated, the normally open reed switch SW remains open, and the equivalent circuit of the normally closed switch is in the closed state; when the triggering magnetic field is generated, the normally open reed switch SW is attracted and conducted, and the equivalent circuit of the normally closed switch is in the open state. The normally closed switch equivalent circuit includes a first resistor R1 and a switching transistor Q1; one end of the first resistor R1 is connected to ground along with the ground terminal of the switching transistor Q1, forming the negative terminal of the product; the other end of the first resistor R1 is connected to the control terminal of the switching transistor Q1 and one end of the normally open reed switch SW; the other end of the normally open reed switch SW is connected to the power supply terminal of the switching transistor Q1 and the cathode of the diode D1, forming the positive terminal of the product; the anode of the diode D1 is connected to the power supply VCC through a pull-up resistor R2. The switching transistor Q1 is a PNP transistor, which is an automotive-grade transistor.

2. The proximity sensor according to claim 1, which replaces the normally closed switch structure, is characterized in that, When no triggering magnetic field is generated, the normally open reed switch SW remains open, the base of the PNP transistor is saturated and turned on by obtaining a forward bias voltage through the first resistor R1, the positive terminal of the product is connected to ground through the conducting transistor, and the equivalent circuit of the normally closed switch is equivalent to the normally closed switch being closed.

3. The proximity sensor according to claim 1, which replaces the normally closed switch structure, is characterized in that, When the trigger magnetic field is generated, the normally open reed switch SW is attracted and turned on. The base of the PNP transistor is shorted to the emitter through the normally open reed switch SW. The PNP transistor loses its forward bias and is turned off. The positive terminal of the product is only connected to the power supply VCC through the pull-up resistor. The equivalent circuit of the normally closed switch is in the open state.

4. The proximity sensor according to claim 1, which replaces the normally closed switch structure, is characterized in that, The first resistor, R1, is an automotive-grade resistor.

5. The proximity sensor according to claim 1, which replaces the normally closed switch structure, is characterized in that, The pull-up resistor R2 is 10kΩ.

6. The proximity sensor according to claim 1, which replaces the normally closed switch structure, is characterized in that, It also includes an external wire, one end of which is soldered to the PCB board and connected to the negative and positive terminals of the product, respectively, and the other end of which extends out of the plastic shell.

7. The proximity sensor according to any one of claims 1-6, which is an alternative to the normally closed switch structure, is characterized in that, The plastic outer shell is a plastic box, and the inside of the plastic box is equipped with a positioning structure for the PCB board. After the PCB board is installed into the plastic box through the positioning structure, it is sealed and cured as a whole by potting epoxy resin.

8. A control circuit for an electric pedal in an automobile, characterized in that, The device includes a proximity sensor circuit as described in any one of claims 1-7, a capacitor C1, a diode D1, a pull-up resistor R2, a resistor R3, a capacitor C2, and a vehicle controller; one end of capacitor C1 is grounded, and the other end is connected to the positive terminal of the proximity sensor and the cathode of diode D1; the anode of diode D1 is connected to the power supply VCC through the pull-up resistor R2 and to one end of capacitor C2 and the IO detection port of the vehicle controller through the resistor R3; the other end of capacitor C2 is grounded; the vehicle controller identifies the position status of the electric pedal of the car based on the high or low level of the IO detection port and controls the motor to start and stop.

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