An electric supporting rod with built-in sensor for automobile tail gate

Abstract

The utility model relates to the field of automobile sensor, concretely relates to a built -in sensor of automobile tail door electric support rod, including code disc, fixed connection is in the motor shaft of electric cylinder or the input shaft of speed reducer and rotates with it, photoelectric sensor contains light emitting element and light receiving element, the code disc includes the bottom plate and the even number of protrusions established on the bottom plate, the protrusions are uniformly distributed on the same circumference, and form the code way between the four protrusions of adjacent two diameter directions, the moving path of protrusion is located between light emitting element and light receiving element, generates pulse signal through the obstruction / transmission light path, in the application scene such as electric tail door requiring low -speed smooth operation and high -precision position control, can guarantee control precision and stability.

Description

Technical Field

[0001] This utility model relates to the field of automotive sensors, specifically to a sensor built into the electric tailgate strut of an automobile. Background Technology

[0002] The electric tailgate system, through buttons integrated into the vehicle, remote key, or innovative foot-activated sensing, enables automatic opening and closing of the tailgate, greatly enhancing the convenience and luxury of vehicle use. Within the entire system, the electric strut is the core actuator responsible for the physical opening and closing action. It typically consists of an outer tube, an inner tube, a motor, a reduction gear mechanism, and a lead screw. The motor drives the lead screw to rotate, thereby extending and retracting the strut. To achieve smooth opening and stopping of the tailgate at any position, height memory, speed control, and the crucial anti-pinch safety function, precise and reliable sensors built into the electric strut motor are essential. These sensors monitor the motor's operating status in real time and feed the data back to the electronic control unit (ECU). Therefore, research on the built-in sensors is key to understanding and evaluating the technological level of modern electric tailgates. Currently, the sensors inside mainstream electric struts primarily revolve around Hall effect sensors and current sensors working in tandem.

[0003] Hall effect sensors are currently the most core and widely used built-in sensor type in electric strut motors. Hall effect sensors accurately sense position, speed, and direction, operating based on the Hall effect. When current passes through a Hall element placed in a magnetic field, a potential difference Hall voltage is generated in a plane perpendicular to both the current and magnetic field directions. The rotation of the permanent magnet on the motor rotor causes periodic changes in the magnetic field strength around the Hall sensor, resulting in the Hall sensor outputting pulse signals related to the motor's speed and position. By placing one or more Hall effect sensors inside the motor, precise monitoring of the motor's operating status can be achieved. The ECU calculates the number of pulses output by the Hall effect sensors to accurately estimate the number of motor rotations, thereby calculating the displacement of the lead screw and ultimately determining the tailgate's opening height. By detecting the frequency of the Hall effect signals, the ECU can determine the motor's real-time speed, enabling "slow opening and slow stopping" of the tailgate during opening and closing, improving the user experience. Simultaneously, by analyzing the phase relationship of multiple Hall effect sensor output signals, the forward and reverse rotation direction of the motor can be accurately determined, ensuring the tailgate opens or closes according to instructions. The built-in current sensor monitors current changes to achieve anti-pinch protection, which is one of the core anti-pinch principles. Current monitoring is typically integrated into the motor drive module or ECU, and can be considered a broad sensing function. During normal operation, the motor's operating current fluctuates within a relatively stable range. When the tailgate encounters an obstacle during closing or opening, the motor load increases instantaneously, causing a sharp spike in its operating current. Hall effect chips and neodymium iron boron magnets are prone to demagnetization at high temperatures, leading to potential failure, and also consume rare earth resources. Current alternative solutions have the following shortcomings: Early or partial solutions may employ independent position sensors such as potentiometers, Hall switch arrays, magnetic encoders, and current sensors such as Hall current sensors and sampling resistors. These solutions are bulky, costly, have complex wiring, and relatively low reliability. Integrated solutions may only integrate position detection functionality, failing to achieve true sensor-level integration. Potentiometers are susceptible to wear and poor contact; some Hall sensors may be vulnerable to electromagnetic interference; single-signal detection may fail or lose accuracy under certain conditions such as low temperature or oil contamination. The internal space of motorized struts is extremely limited, necessitating highly integrated sensor solutions to reduce costs and meet installation requirements. There is a lack of sensor solutions that can simultaneously provide high-precision, high-reliability position signals and are easy to integrate. Since most systems use four pulses per revolution, using Hall chips with more pulses and multi-segment radially magnetized magnets significantly increases costs. Utility Model Content

[0004] The purpose of this invention is to provide a built-in sensor for the electric tailgate strut of an automobile, eliminating the need for Hall effect sensors and their related wiring. This has the advantages of reducing costs and potential failure points. In applications such as electric tailgates that require low-speed, stable operation and high-precision position control, it can ensure control accuracy and stability.

[0005] The objective of this utility model is achieved through the following technical solution: A sensor built into an electric tailgate strut for automobiles includes: The encoder 1 is fixedly connected to the motor shaft 2 of the electric cylinder or the input shaft of the reducer and rotates with it; The photoelectric sensor 3 includes a light emitter 31 and a light receiver 32; The code disk 1 includes a base plate 11 and an even number of protrusions 12 on the base plate. The protrusions 12 are evenly distributed on the same circumference, and a code track 13 is formed between four protrusions in two adjacent diameter directions. The moving path of the protrusion 12 is located between the light emitter 31 and the light receiver 32, and generates a pulse signal by blocking / transmitting the light path.

[0006] As a preferred technical solution of this utility model, the number of photoelectric sensors 3 is 2, arranged along the arc of the circumference of the protrusion 12, with the central angle of the two sensors being 5°-179°, providing dual-path detection and improving reliability.

[0007] As a preferred technical solution of this utility model, the number of code channels 13 is 4.

[0008] As a preferred technical solution of this utility model, the photoelectric sensor 3 further includes a circuit board 33, and the light emitting element 31 and the light receiving element 32 are integrated on the circuit board 33.

[0009] As a preferred technical solution of this utility model, the base plate 11 is circular, and the protrusion 12 is provided on the edge of the base plate.

[0010] As a preferred technical solution of this utility model, the protrusion 12 is in the shape of a cuboid.

[0011] As a preferred technical solution of this utility model, the base plate 11 is provided with a mounting hole 14 at the center, and the mounting hole 14 is interference-fitted with the motor shaft 2.

[0012] As a preferred technical solution of this utility model, the built-in sensor also includes a sealed housing 4, in which the photoelectric sensor 3 and the code disk 1 are partially housed, and the gaps in the housing are filled with sealant.

[0013] The beneficial effects are as follows: This invention replaces the Hall sensor with a photoelectric sensor and a raised-code track structure of the code disk, directly eliminating the use of rare earth magnet neodymium iron boron and Hall chip, reducing material costs by more than 30% (inventive destruction theory), while reducing sensor wiring complexity and reducing system failure rate by 25%.

[0014] The evenly distributed circumferential design of this invention allows for a freely definable number of pulses per revolution, such as 16 pulses per revolution for 4 tracks. Position detection accuracy is improved to ±0.5°, and the increased resolution does not require additional magnetic partitioning costs. Improved position signal accuracy reduces the anti-pinch trigger response time to 50ms, enhancing obstacle recognition. The pulse linearity supports stepless speed regulation, improving the smoothness of tailgate opening and stopping. The photoelectric detection principle of this invention completely avoids the risk of high-temperature demagnetization. The failure temperature of the Hall effect scheme is >80℃, and the working temperature range is extended to -40℃~150℃, meeting the automotive-grade AEC-Q102 requirements. At the same time, its non-magnetic characteristics improve its electromagnetic interference resistance by 60%.

[0015] The dual photoelectric sensor layout of this invention, ranging from 5° to 179°, improves the reliability of redundant detection and can still maintain basic functions even when a single sensor fails. The angle optimization avoids blind spots, and the dual signal paths inevitably improve the fault tolerance rate.

[0016] The optoelectronic device of this invention is integrated into the circuit board, and the integrated structure reduces mechanical connection points. The encoder disk adapts to the arc-shaped space of the motor's rear end cover, resulting in a small overall thickness of the sensor. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the built-in sensor of the electric tailgate support rod of this utility model.

[0018] Figure 2 This is a front view of the built-in sensor of the electric tailgate strut of this utility model.

[0019] Figure 3 This is a left view of the built-in sensor of the electric tailgate strut of this utility model.

[0020] Figure 4 This is a cross-sectional view of the built-in sensor of the electric tailgate support rod of this utility model.

[0021] Figure 5 This is a schematic diagram of the structure of the built-in sensor in the electric tailgate strut of this utility model. Figure 1 Different angles.

[0022] Figure 6 This is a schematic diagram of the structure of the photoelectric sensor of this utility model.

[0023] Figure 7 This is a schematic diagram of the structure of the encoder of this utility model.

[0024] Figure 8 This is the front view of the encoder of this utility model.

[0025] Figure 9 This is a left view of the encoder of this utility model. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0027] like Figures 1 to 8 As shown, this utility model provides a built-in sensor for an electric tailgate strut, including a code disk 1, which is fixedly connected to the motor shaft 2 of the electric cylinder or the input shaft of the reducer and rotates with it; a photoelectric sensor 3, including a light emitter 31 and a light receiver 32; the code disk 1 includes a base plate 11 and an even number of protrusions 12 disposed on the base plate, the protrusions 12 are evenly distributed on the same circumference, and a code track 13 is formed between four protrusions in two adjacent diameter directions; the moving path of the protrusions 12 is located between the light emitter 31 and the light receiver 32, and a pulse signal is generated by blocking / transmitting the light path.

[0028] Example 1: A sensor built into an electric tailgate strut is mounted on a motor shaft. The encoder 1 is interference-fitted with the motor shaft 2 of the electric cylinder through a central mounting hole 14. The mounting hole has a diameter of 6mm and a tolerance of H7. Axial fixation is achieved using an elastic retaining ring. Figure 4 The base plate 11 is a 1.5mm thick, 30mm diameter circular sheet of 304 stainless steel. Eight rectangular protrusions 12 are evenly distributed along the edge. The dimensions of each protrusion are: length × width × height = 3mm × 2mm × 4mm, and the center angle between adjacent protrusions is 45°. Figure 6-8 The circuit board 33 of the photoelectric sensor 3 is fixed inside the rear end cover of the motor. The light emitter 31 (Everlight IR333-A) and the light receiver 32 (VishayTEFT4300) are spaced 4mm apart and directly opposite the protruding rotation path. Figure 2 When motor shaft 2 rotates, protrusion 12 periodically blocks the light path. Each protrusion-code track combination generates two rising / falling pulses. The 8-protrusion design achieves 16 pulses / revolution, compared to the typical 4 pulses / revolution of a Hall effect sensor. The pulse signal is decoded by the STM32G431KB on circuit board 33 and the position data is output to the tailgate ECU via the LIN bus. Figure 1 The test results are shown in Table 1 below. Test Project Example 1 Traditional Hall scheme Increase Position resolution 22.5° / pulse 90° / pulse 75% Installation space occupancy 8mm axial 15mm 46.7% Unit material cost ￥23.5 ￥37.8 37.8%

[0029] Example 2: A sensor built into the electric tailgate strut of a car is mounted on the motor shaft. Based on the solution in Example 1, a second set of photoelectric sensors 3' is added. The two sets of sensors are symmetrically arranged along the circumference of the protrusion with a central angle of 50°, sharing the same circuit board 33. Figure 5 When the main sensor 3 fails, it automatically switches to the backup sensor 3'; when both channels are normal, the average value is taken, with a position error ≤ ±0.3° compared to ±0.5° for a single channel. The optoelectronic device is an AEC-Q102 certified model, such as Broadcom AFBR-2521Z, with an operating temperature range of -40℃ to 150℃. Vibration test: After 96 hours of random vibration with an amplitude of 1.5mm at 10Hz-500Hz, the signal distortion rate is <3%, compared to >15% for traditional Hall effect solutions.

[0030] Example 3: A sensor built into the electric tailgate strut of a car is installed on the motor shaft. In Example 1, an aluminum alloy sealed housing 4 encloses the encoder 1 and the photoelectric sensor 3. The space between the housing and the motor end cover is filled with high-temperature resistant silicone (Dow Corning 1-2577), with an IP6K / 9K protection rating, resistant to high-pressure water jets / oil penetration. Figure 4 The electrical connector uses a TEConnectivity AMPSEAL 16-pin interface, supporting 12V power supply and CAN FD communication. A 5mΩ sampling resistor with 0.1% accuracy is connected in series in the motor grounding circuit. The TI INA240 operational amplifier circuit amplifies the differential voltage in real time. The ECU sets a current threshold of 8A, corresponding to a pressure of 15MPa, to trigger anti-pinch reverse rotation. Test data: obstacle recognition response time 48ms (compared to 85ms for traditional solutions), false trigger rate <0.1%.

[0031] This invention provides a built-in sensor for an electric cylinder, preferably integrated inside the motor's rear end cover or stator end, for detecting the position and rotation angle of the motor's output shaft. Its core components include a code disk, a photoelectric detection module, and an auxiliary unit. The code disk has a disc-shaped structure and is interference-fitted with the motor's output shaft or the reducer's input shaft through a central mounting hole, rotating synchronously with the shaft. An even number of cuboid protrusions are evenly distributed along the edge of the disk surface, with four protrusions in the adjacent diameter direction forming a light code track. The photoelectric detection module includes a printed circuit board (PCB), on which light emitters such as infrared LEDs, light receivers such as phototransistors, and signal processing circuitry are integrated. The photoelectric devices face the rotation path of the protrusions, with a 0.5-2mm air gap between them. The auxiliary unit includes a multi-pin connector and a sealed housing: the multi-pin connector outputs position / current signals and connects to the power supply and grounding lines; the sealed housing covers the PCB and code disk, with the housing gaps filled with high-temperature resistant silicone to achieve an IP6K / 9K protection rating.

[0032] The position detection process of this utility model is divided into three stages: the motor shaft drives the encoder to rotate, and the protrusion periodically blocks the light path, causing the light receiver to output a pulse sequence; the PCB decoding circuit converts the number of pulses into a rotation angle, for example, the 8-protrusion structure outputs 16 pulses / revolution, corresponding to a resolution of 22.5°, and filters out electromagnetic interference through a differential algorithm, while calculating the real-time rotation speed based on the pulse change rate; the position signal POS_Signal is output to the ECU as a 0-5V analog voltage or PWM / digital signal.

[0033] The current detection process of this utility model includes three steps: connecting a high-precision sampling resistor with a resistance value of 5mΩ±0.1% in series to the motor drive circuit; the PCB operational amplifier circuit detects the voltage drop across the sampling resistor, amplifies it, and outputs a voltage signal proportional to the current; the ECU sets a current threshold, for example, 8A corresponding to 15MPa pressure, and triggers the tailgate reversal mechanism when the limit is exceeded.

[0034] This invention utilizes a single connector to simultaneously output position and current signals, forming a dual-signal collaborative mechanism: the position signal is used to calculate the tailgate height and direction of movement, while the current signal monitors the load torque in real time, providing a closed-loop control basis for the ECU and reducing the anti-pinch response time to ≤50ms. The highly integrated design integrates optoelectronic devices, sampling resistors, and processing circuits onto a single PCB, occupying ≤8mm of axial space, a 46.7% reduction compared to a split-type solution. The anti-interference mechanism includes dual protection: optical non-contact detection avoids electromagnetic interference; the sealed housing resists oil and moisture corrosion, resulting in a failure rate of <0.1% across the entire temperature range of -40℃ to 150℃, completely solving the failure problem of traditional Hall effect sensors above 80℃.

[0035] Comparative testing verified the core performance: The position sensor failure rate was 0% after 48 hours of continuous operation at 150℃, significantly better than the traditional solution's 100% magnet demagnetization failure; after 96 hours of random vibration testing at 10Hz-500Hz, the signal distortion rate was <3%, an 83% improvement compared to the 15% distortion rate of the split-type solution; dual-signal synchronous output reduced the anti-pinch response time to 48ms, a 43.5% improvement compared to the industry benchmark of 85ms. All experimental data were verified by IEC 60068-2-14 temperature cycling test and ISO 16750-3 mechanical vibration standard.

[0036] In other embodiments, the number of photoelectric sensors is two, located on the arc of the circle containing the protrusion, with a central angle of 5-179 degrees.

[0037] In other embodiments, the number of photoelectric sensors is two, located on the arc of the circle containing the protrusion, with a central angle of 50 degrees.

[0038] In other embodiments, the number of code tracks is four.

[0039] In other embodiments, the photoelectric sensor includes a circuit board and a light receiver and a light emitter connected to the circuit board.

[0040] In other embodiments, the base plate of the encoder is circular, with protrusions located at the edge of the circular base plate.

[0041] In other embodiments, the protrusion is in the shape of a cuboid.

[0042] In other embodiments, the base plate has a mounting hole at its center, which is interference-fitted with the motor shaft.

[0043] This invention significantly reduces the sensor size, saving valuable internal space in the motor and simplifying the strut assembly structure. It reduces the number of independent sensors, connectors, and wiring harnesses, thus lowering assembly costs. The reduction in external connection points and wiring harnesses lowers the failure rate; optimized anti-interference design enhances stability in the harsh electromagnetic environment of automobiles; physical integration reduces independent mounting points sensitive to vibration. It provides synchronous and direct position and torque signals, enabling the ECU to achieve faster and more precise position control. Speed ​​control is achieved through position differential, and anti-pinch control torque / current signals are more direct, along with overload protection, improving the smoothness, safety, and user experience of tailgate operation. For the ECU, only two standard signals from a single connector need to be processed, simplifying the interface. The sensor is installed and replaced as a single module, making installation and replacement convenient and quick.

[0044] This invention improves the fault detection rate by 40% compared to single magnetic switches and reduces the cost of tailgate strut sensors by more than 50%.

[0045] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A sensor built into an electric tailgate strut for automobiles, characterized in that, include: The encoder (1) is fixedly connected to the motor shaft (2) of the electric cylinder or the input shaft of the reducer and rotates with it; The photoelectric sensor (3) includes a light emitter (31) and a light receiver (32). The code disk (1) includes a base plate (11) and an even number of protrusions (12) on the base plate. The protrusions (12) are evenly distributed on the same circumference, and a code track (13) is formed between four protrusions in two adjacent diameter directions. The movement path of the protrusion (12) is located between the light emitter (31) and the light receiver (32), and generates a pulse signal by blocking / transmitting the light path.

2. The built-in sensor on the electric tailgate strut as described in claim 1, characterized in that, The number of photoelectric sensors (3) is 2, arranged along the arc of the circumference of the protrusion (12), and the central angle of the two sensors is 5°-179°.

3. The built-in sensor on the electric tailgate strut as described in claim 1, characterized in that, The number of code channels (13) is 4.

4. The built-in sensor on the electric tailgate strut as described in claim 1, characterized in that, The photoelectric sensor (3) also includes a circuit board (33), on which the light emitter (31) and the light receiver (32) are integrated.

5. The built-in sensor on the electric tailgate strut as described in claim 1, characterized in that, The base plate (11) is circular, and the protrusion (12) is located on the edge of the base plate.

6. The built-in sensor on the electric tailgate strut as described in claim 1, characterized in that, The protrusion (12) is rectangular in shape.

7. The built-in sensor on the electric tailgate strut as described in claim 1, characterized in that, The base plate (11) has a mounting hole (14) at its center, and the mounting hole (14) is interference-fitted with the motor shaft (2).

8. The built-in sensor on the electric tailgate strut as described in claim 1, characterized in that, The built-in sensor also includes a sealed housing (4), in which the photoelectric sensor (3) and the code disk (1) are partially housed, and the gaps in the housing are filled with sealant.

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