Electric opening and closing and stepless position holding system for side-hinged tailgate of automobile

Abstract

The application relates to the technical field of automobile body accessories, in particular to an electric opening and closing and stepless position keeping system for a side-opening type tail door of an automobile, which comprises an electric supporting rod, an ECU and a stepless position limiter. The electric supporting rod is internally integrated with a motor-gearbox, a screw rod and a Hall sensor, can output linear force to generate a driving torque rotating around a vertical shaft, the stepless position limiter is a pure passive hydraulic device, is decoupled with the electric supporting rod control, and is used to provide damping and hydraulic locking at any position, the ECU collects Hall signals to realize closed-loop control, switches a high force mode to compact the sealing strip at the end of door closing, and has millisecond-level anti-pinch protection. The application decouples the active driving and passive keeping functions, realizes full-automatic opening and closing of the side-opening type tail door, stepless hovering at any opening degree and manual operation in power-off mode, has the advantages of compact structure, low energy consumption and high reliability, and is particularly suitable for off-road vehicles with an external spare tire.

Description

Technical Field

[0001] This invention relates to the field of automotive body accessory technology, and in particular to an electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile. Background Technology

[0002] As consumers increasingly demand greater convenience in car use, electric tailgate systems have become widely used in the passenger vehicle market. Currently, mainstream electric tailgate solutions are all designed for lift-up tailgates (i.e., tailgates that open by flipping upwards around a horizontal hinge axis), achieving fully automatic opening and closing through a linear electric strut in conjunction with an electronic control unit (ECU).

[0003] However, in off-road vehicles and professional SUVs, side-opening tailgates (where the tailgate rotates to one side around a vertical hinge axis) are widely used due to their distinctive design and ease of loading. These types of vehicles often also integrate an external spare tire into their side-opening tailgates, further increasing the tailgate's mass and rotational inertia.

[0004] In existing technologies, side-opening tailgates generally have the following problems:

[0005] The lack of electrification capability is a significant issue. Currently, almost all side-opening tailgates on the market are purely manual, requiring users to manually push and pull the tailgate to open and close it. As vehicles become increasingly intelligent, manual operation can no longer meet users' needs for convenience, especially in scenarios such as carrying heavy loads, in inclement weather, or at night, where the manual operation experience is poor.

[0006] The top-hinged electric tailgate system cannot be directly transplanted. In existing mature top-hinged electric tailgate solutions, the linear electric strut is arranged along the door's flipping direction, and its axis of motion is adapted to the horizontal hinge axis. However, the rotation axis of a side-opening tailgate is vertical, and the direction of gravity generated by the tailgate's mass (including the spare tire, which can reach 60-80 kg) is parallel to the rotation axis, thus not generating torque in the opening and closing direction. Its opening and closing driving force needs to be applied in the horizontal plane, and the driving principle is fundamentally different from that of the top-hinged tailgate. Therefore, the existing top-hinged electric system cannot be directly applied to the side-opening tailgate.

[0007] There is currently no complete system solution in the technology that is simple in structure, cost-controllable, and can realize fully automatic electric opening and closing of the side-opening tailgate and stepless holding function at any position. The above-mentioned technological gaps need to be filled. Summary of the Invention

[0008] To overcome the shortcomings of existing systems, this invention provides an electric opening and closing system and a stepless position holding system for a side-opening tailgate of an automobile.

[0009] The technical solution adopted by this invention to solve its technical problem is: an electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile, comprising an electric strut, one end of which is connected to a first fixed mounting point B1 on the vehicle body via a ball joint on the vehicle body side, and the other end of which is connected to a first follow-up mounting point T1 on the tailgate via a ball joint on the tailgate side; the electric strut integrates a motor-gearbox assembly, a wiring harness assembly, a lead screw assembly, and a Hall sensor; the electric strut is a springless strut, used to reduce electrical energy through the motor-gearbox assembly and convert it through the lead screw assembly, and then output a linear push-pull force through a push rod; the Hall sensor is used to output a digital pulse signal corresponding to the position of the motor rotor magnetic pole in real time;

[0010] The electronic control unit (ECU) is mounted on a mounting bracket inside the tailgate body and is electrically connected to the electric strut via the wiring harness assembly. The ECU is configured to collect the number and frequency of pulses from the Hall sensor to calculate the current extension amount and movement speed of the push rod, thereby achieving closed-loop position control.

[0011] The limit switch includes a limit switch body, one end of which is fixed to the second fixed mounting point B2 on the vehicle body via a hinge joint on the vehicle side and a bracket, and the other end is hinged to the second follower mounting point T2 on the tailgate via a ball joint on the tailgate side; the limit switch is a purely passive hydraulic device, and is equipped with a sealing component, a hydraulic chamber, an oil passage and a throttle valve inside;

[0012] The linear push / pull force F1 output by the electric strut 1 acts on the first follower mounting point T1. This force, together with the vertical distance d1 from T1 to the center H of the vertical hinge axis, constitutes the torque M_drive that drives the door body to rotate around the vertical hinge axis. When the component torque generated by the driving torque at T2 exceeds the hydraulic holding torque M_stop of the limit switch, the hydraulic oil flows through the throttle valve under the action of pressure difference, allowing the door body to move. When the driving force is removed, the hydraulic oil stops flowing, and the limit switch automatically forms a hydraulic static holding.

[0013] Furthermore, the mating structure of the ball joint on the vehicle side and the first fixed mounting point B1, the mating structure of the ball joint on the tailgate side and the first follower mounting point T1, the mating structure of the hinge joint on the vehicle side and the second fixed mounting point B2, and the mating structure of the ball joint on the tailgate side and the second follower mounting point T2 are all configured to allow the corresponding components to follow the direction of rotation during the rotation of the door body, so as to adapt to the continuous change of the direction of the strut axis.

[0014] Furthermore, the ECU is further configured as follows:

[0015] It receives the user's opening and closing commands and controls the movement direction and speed curve of the electric strut based on the built-in position parameters and the current position information;

[0016] At the end of the closing phase, when it is determined that the distance between the door body and the fully closed position is within the preset angle range, it automatically switches to high-force output mode to increase the driving torque to overcome the elastic restoring force of the sealing strip and achieve sealing and pressing control.

[0017] Furthermore, the ECU also has an anti-pinch protection function: it monitors the drive current of the motor-gearbox assembly in real time, and when it detects a sudden increase in current caused by abnormal resistance due to an obstacle, it controls the motor to stop running and reverses the drive to perform a short-distance retreat.

[0018] Furthermore, the working response of the limitless positioner is entirely driven by external force, and its hydraulic holding torque M_stop is a constant or a set value that varies with displacement; after the electric strut stops outputting driving torque, regardless of the opening degree of the door, the hydraulic oil inside the limitless positioner stops flowing, forming a static lock at the current position, and the holding state does not require continuous power supply.

[0019] Furthermore, the effective driving torque M_drive output by the electric strut satisfies the torque constraint formula: M_drive ≥ M_stop + M_f + M_g + M_i; where M_drive is the effective driving torque of the electric strut; M_stop is the hydraulic holding torque without limit switch; M_f is the friction torque of the vertical hinge bearing; M_g is the gravity component torque under ramp conditions; M_i is the inertial torque generated by the rotational inertia of the tailgate; the rated output force of the electric strut has a safety margin of not less than 20% based on the sum of all resistance torques.

[0020] Furthermore, the electric strut 1 and the limitless positioner 3 are completely decoupled at the control level, and there is no electrical signal interaction between them; the electric strut is dedicated to the active drive function, and the limitless positioner 3 is dedicated to the passive damping and position holding function, and the two are only mechanically coupled through the tailgate.

[0021] Furthermore, M_drive = F1 × d1(θ) dynamically changes with the opening angle θ;

[0022] The formula M_f = W × r × μ is given, where r is the bearing contact radius and μ is the coefficient of friction.

[0023] M_g is the gravity component torque under ramp conditions, which is generated when the vehicle is parked on the ramp, causing the hinge axis to deviate from the vertical direction. Its maximum value is W × L_cg × sinα, where W is the total weight of the door, L_cg is the horizontal distance from the center of mass to the hinge axis, and α is the angle at which the hinge axis deviates from the vertical direction.

[0024] M_i = J × α_angular, where J is the moment of inertia and α_angular is the angular acceleration.

[0025] The beneficial effects of this invention are as follows: It proposes a complete electrification solution for side-opening tailgates for the first time, solving the problem of the inability to transplant top-hinged electric systems; the electric strut is responsible for active drive, while the limit switch is responsible for passive damping and holding, with no electrical interconnection between the two, relying solely on mechanical coupling, thus reducing system complexity and improving reliability; the limit switch utilizes hydraulic static locking to achieve stable tailgate holding at any opening degree, effectively resisting crosswinds and ramp torques, and maintaining zero power consumption during the holding process; it features anti-pinch protection, soft start / stop, and sealing pressure control, improving NVH performance; in manual mode, no unlocking mechanism is required, and smooth operation is still possible even in the event of a power outage, achieving seamless compatibility between manual and electric modes. Attached Figure Description

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

[0027] Figure 1 This is a layout diagram of the electric opening and closing and stepless position holding system;

[0028] Figure 2 This is a schematic diagram of the electric strut structure;

[0029] Figure 3 This is a schematic diagram of a limitless positioner structure;

[0030] Figure 4 This is a flowchart of the electric door opening process;

[0031] Figure 5 This is a flowchart of the electric door closing process.

[0032] In the diagram: 1. Electric strut; 11. Motor and gearbox assembly; 12. Wiring harness assembly; 13. Lead screw assembly; 14. Push rod; 15. Side ball joint; 16. Tailgate side ball joint; 2. Electronic control unit (ECU); 3. Limit switch; 31. Limit switch body; 32. Bracket; 33. Side hinge joint; 34. Tailgate side ball joint. Detailed Implementation

[0033] like Figures 1-3This is a schematic diagram of the structure of the present invention, an electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile, comprising an electric strut 1, one end of which is connected to a first fixed mounting point B1 on the vehicle body via a ball joint 15 on the vehicle body side, and the other end of which is connected to a first follow-up mounting point T1 on the tailgate via a ball joint 16 on the tailgate side; the electric strut 1 integrates a motor-gearbox assembly 11, a wiring harness assembly 12, a lead screw assembly 13, and a Hall sensor; the electric strut 1 is a springless strut, used to reduce electrical energy through the motor-gearbox assembly 11 and convert it through the lead screw assembly 13, and then output a linear push-pull force through a push rod 14; the Hall sensor is used to output a digital pulse signal corresponding to the position of the motor rotor magnetic poles in real time.

[0034] The electronic control unit ECU2 is installed on the mounting bracket inside the tailgate body and is electrically connected to the electric strut 1 through the wiring harness assembly 12. The ECU2 is configured to collect the number and frequency of pulses from the Hall sensor to calculate the current extension amount and movement speed of the push rod 14, thereby realizing closed-loop position control.

[0035] The limit switch 3 includes a limit switch body 31. One end of the limit switch body 31 is connected to the second fixed mounting point B2 on the vehicle body through a body-side hinge joint 33 and a bracket 32, and the other end is connected to the second follow-up mounting point T2 on the tailgate through a tailgate-side ball socket 34. The limit switch 3 is a purely passive hydraulic device, which is equipped with a sealing component, a hydraulic chamber, an oil passage and a throttle valve inside.

[0036] The linear push / pull force F1 output by the electric strut 1 acts on the first follower mounting point T1. This force, together with the vertical distance d1 from T1 to the center H of the vertical hinge axis, constitutes the torque M_drive that drives the door body to rotate around the vertical hinge axis. When the component torque generated by the driving torque at T2 exceeds the hydraulic holding torque M_stop of the limit switch 3, the hydraulic oil flows through the throttle valve under the action of pressure difference, allowing the door body to move. When the driving force is removed, the hydraulic oil stops flowing, and the limit switch 3 automatically forms a hydraulic static hold.

[0037] Furthermore, the mating structure of the ball joint 15 on the vehicle side and the first fixed mounting point B1, the mating structure of the ball joint 16 on the tailgate side and the first follow-up mounting point T1, the mating structure of the hinge joint 33 on the vehicle side and the second fixed mounting point B2, and the mating structure of the ball joint 34 on the tailgate side and the second follow-up mounting point T2 are all configured to allow the corresponding components to follow the direction of rotation during the rotation of the door body, so as to adapt to the continuous change of the direction of the strut axis.

[0038] Furthermore, the ECU2 is further configured as follows:

[0039] It receives the user's opening and closing commands and controls the movement direction and speed curve of the electric strut 1 according to the built-in position parameters and the current position information;

[0040] At the end of the closing phase, when it is determined that the distance between the door body and the fully closed position is within the preset angle range, it automatically switches to high-force output mode to increase the driving torque to overcome the elastic restoring force of the sealing strip and achieve sealing and pressing control.

[0041] Furthermore, the ECU2 also has an anti-pinch protection function: it monitors the drive current of the motor-gearbox assembly 11 in real time, and when it detects an abnormal resistance caused by an obstacle that causes a sudden increase in current, it controls the motor to stop running and reverses the drive to perform a short-distance retreat.

[0042] Furthermore, the working response of the limitless positioner 3 is entirely driven by external force, and its hydraulic holding torque M_stop is a constant or a set value that varies with displacement; after the electric strut 1 stops outputting driving torque, regardless of the opening degree of the door, the hydraulic oil inside the limitless positioner 3 stops flowing, forming a static lock at the current position, and the holding state does not require continuous power supply.

[0043] Furthermore, the effective driving torque M_drive output by the electric strut satisfies the torque constraint formula: M_drive ≥ M_stop + M_f + M_g + M_i; where M_drive is the effective driving torque of the electric strut; M_stop is the hydraulic holding torque without limit switch; M_f is the friction torque of the vertical hinge bearing; M_g is the gravity component torque under ramp conditions; M_i is the inertial torque generated by the rotational inertia of the tailgate; the rated output force of the electric strut has a safety margin of not less than 20% based on the sum of all resistance torques.

[0044] Furthermore, the electric strut 1 and the limitless positioner 3 are completely decoupled at the control level, and there is no electrical signal interaction between them; the electric strut 1 is dedicated to the active driving function, and the limitless positioner 3 is dedicated to the passive damping and position holding function, and the two are only mechanically coupled through the tailgate.

[0045] Furthermore,

[0046] The value M_drive = F1 × d1(θ) changes dynamically with the opening angle θ.

[0047] The formula M_f = W × r × μ is given, where r is the bearing contact radius and μ is the coefficient of friction.

[0048] M_g is the gravity component torque under ramp conditions, which is generated when the vehicle is parked on the ramp, causing the hinge axis to deviate from the vertical direction. Its maximum value is W × L_cg × sinα, where W is the total weight of the door, L_cg is the horizontal distance from the center of mass to the hinge axis, and α is the angle at which the hinge axis deviates from the vertical direction.

[0049] M_i = J × α_angular, where J is the moment of inertia and α_angular is the angular acceleration.

[0050] Detailed explanation of working principle:

[0051] 1. Electric door opening process:

[0052] The ECU receives user door opening commands (such as pressing the key, pressing an in-vehicle button, or using a foot sensor) from the vehicle control unit (BCM) via the CAN / LIN bus. After confirming the door status, the ECU controls the motor of electric strut 1 to rotate forward, and push rod 14 extends, generating driving torque M_drive.

[0053] At this point, M_drive needs to overcome the hydraulic holding torque M_stop of the limit switch 3, the hinge friction torque M_f, the gravity component torque of the ramp M_g, and the inertial torque M_i during startup. When M_drive is greater than the sum of these torques, the hydraulic oil in the limit switch 3 begins to flow, and the door rotates around the vertical hinge axis H.

[0054] During operation, the ECU uses a three-stage speed curve control (acceleration upon start, constant speed operation, and deceleration upon arrival) based on Hall signals to ensure smooth movement. Simultaneously, the ECU monitors the motor current in real time. If an obstacle is encountered that causes an abnormal increase in current, the anti-pinch algorithm is immediately triggered, stopping the motor and reversing it a short distance.

[0055] When the position signal from the Hall sensor indicates that the door has reached the target opening degree (such as the maximum opening degree), the ECU controls the motor to stop. At this time, M_drive returns to zero, the hydraulic oil in the limit switch 3 stops flowing, and a static hold is formed instantly. Even if there is a crosswind or the vehicle is on a slope, the door will not shake or close automatically, and this process does not consume electricity.

[0056] 2. Electric door closing process:

[0057] After receiving the door closing command, the ECU controls the electric strut 1 motor to reverse, the push rod 14 retracts, and generates a reverse torque to pull the door closed.

[0058] Similar to the door opening process, the ECU performs closed-loop speed control and anti-pinch monitoring. Specifically, when the ECU determines that the door is approximately 10°~15° away from the fully closed position through Hall pulse counting, the system enters the "sealing and pressing mode". At this time, the ECU controls the motor to output greater torque to overcome the compression resistance of the sealing strip, ensuring that the tailgate fits tightly against the body, improving the overall vehicle sealing and NVH performance.

[0059] After the door is closed, the motor stops running, and the limit switch 3 provides hydraulic holding force in the fully closed position, which helps the latch maintain the closed state.

[0060] 3. Manual operation mode:

[0061] In the event of a power outage or system malfunction, the user can manually push or pull the tailgate. Since the limit switch 3 is a purely passive device, when the torque applied by the user exceeds its hydraulic holding torque M_stop, the hydraulic channel automatically opens, allowing the user to operate the tailgate like a regular manual tailgate. Upon releasing the hand, the hydraulic oil stops flowing, and the tailgate immediately remains in its new position. The entire process requires no additional electromagnetic unlocking mechanism, making the structure simple and reliable.

[0062] The above description is illustrative only and not restrictive of the present invention. Those skilled in the art will understand that many modifications, variations or equivalents can be made without departing from the spirit and scope defined by the appended claims, and all such modifications, variations or equivalents will fall within the protection scope of the present invention.

Claims

1. An electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile, characterized in that, An electric strut (1) has one end connected to a first fixed mounting point (B1) on the vehicle body via a ball joint (15) on the side of the vehicle body, and the other end connected to a first follow-up mounting point (T1) on the tailgate via a ball joint (16) on the side of the tailgate. The electric strut (1) integrates a motor-gearbox assembly (11), a wiring harness assembly (12), a lead screw assembly (13), and a Hall sensor. The electric strut (1) is a springless strut, used to reduce electrical energy through the motor-gearbox assembly (11) and convert it through the lead screw assembly (13), and then output a linear push-pull force through a push rod (14). The Hall sensor is used to output a digital pulse signal corresponding to the position of the motor rotor magnetic pole in real time. An electronic control unit (ECU) (2) is installed on a mounting bracket inside the tailgate and is electrically connected to the electric strut (1) via the wiring harness assembly (12); the ECU (2) is configured to collect the number and frequency of pulses from the Hall sensor to calculate the current extension amount and movement speed of the push rod (14) and realize closed-loop position control. The limit switch (3) includes a limit switch body (31), one end of which is connected to the second fixed mounting point (B2) on the vehicle body through a body side hinge joint (33) and a bracket (32), and the other end is connected to the second follow-up mounting point (T2) on the tailgate through a tailgate side ball socket (34); the limit switch (3) is a purely passive hydraulic device, and is equipped with a sealing component, a hydraulic chamber, an oil passage and a throttle valve inside; The linear push / pull force F1 output by the electric strut (1) acts on the first follower mounting point (T1). This force and the vertical distance d1 from T1 to the center of the vertical hinge axis (H) constitute the torque M_drive that drives the door body to rotate around the vertical hinge axis. When the component torque generated by the driving torque at T2 exceeds the hydraulic holding torque M_stop of the limitless positioner (3), the hydraulic oil flows through the throttle valve under the action of pressure difference, allowing the door body to move. When the driving force is removed, the hydraulic oil stops flowing, and the limitless positioner (3) automatically forms a hydraulic static hold.

2. The electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile according to claim 1, characterized in that, The mating structure of the ball joint (15) on the vehicle side and the first fixed mounting point (B1), the mating structure of the ball joint (16) on the tailgate side and the first follower mounting point (T1), the mating structure of the hinge joint (33) on the vehicle side and the second fixed mounting point (B2), and the mating structure of the ball joint (34) on the tailgate side and the second follower mounting point (T2) are all configured to allow the corresponding components to follow the direction of rotation during the rotation of the door body, so as to adapt to the continuous change of the direction of the strut axis.

3. The electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile according to claim 1, characterized in that, The ECU (2) is further configured as follows: Receives the user's opening and closing commands, and controls the movement direction and speed curve of the electric strut (1) according to the built-in position parameters and the current position information; At the end of the closing phase, when it is determined that the distance between the door body and the fully closed position is within the preset angle range, it automatically switches to high-force output mode to increase the driving torque to overcome the elastic restoring force of the sealing strip and achieve sealing and pressing control.

4. The electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile according to claim 1, characterized in that, The ECU (2) also has an anti-pinch protection function: real-time monitoring of the drive current of the motor-gearbox assembly (11), and when an abnormal resistance caused by an obstacle is detected, causing a sudden increase in current, controlling the motor to stop running and reverse driving to perform a short-distance retreat.

5. The electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile according to claim 1, characterized in that, The working response of the limitless positioner (3) is driven entirely by external force, and its hydraulic holding torque M_stop is a constant or a set value that varies with displacement. After the electric strut (1) stops outputting driving torque, the hydraulic oil inside the limitless positioner (3) stops flowing regardless of the opening degree of the door, forming a hydraulic static lock at the current position, and the holding state does not require continuous power supply.

6. The electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile according to claim 1, characterized in that, The effective driving torque M_drive output by the electric strut satisfies the torque constraint formula: M_drive ≥ M_stop + M_f + M_g + M_i; where M_drive is the effective driving torque of the electric strut; M_stop is the hydraulic holding torque without limit switch; M_f is the friction torque of the vertical hinge bearing; M_g is the gravity component torque under ramp conditions; and M_i is the inertial torque generated by the rotational inertia of the tailgate. The rated output force of the electric strut has a safety margin of not less than 20% based on the sum of all resistance torques.

7. The electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile according to claim 1, characterized in that, The electric strut (1) and the limitless positioner (3) are completely decoupled at the control level, and there is no electrical signal interaction between them. The electric strut (1) is dedicated to the active driving function, and the limitless positioner (3) is dedicated to the passive damping and position holding function. The two are only mechanically coupled through the tailgate.

8. The electric opening and closing and stepless position holding system for a side-opening tailgate of an automobile according to claim 6, characterized in that, The value M_drive = F1 × d1(θ) changes dynamically with the opening angle θ. The formula M_f = W × r × μ is given, where r is the bearing contact radius and μ is the coefficient of friction. M_g is the gravity component torque under ramp conditions, which is generated when the vehicle is parked on the ramp, causing the hinge axis to deviate from the vertical direction. Its maximum value is W × L_cg × sinα, where W is the total weight of the door, L_cg is the horizontal distance from the center of mass to the hinge axis, and α is the angle at which the hinge axis deviates from the vertical direction. M_i = J × α_angular, where J is the moment of inertia and α_angular is the angular acceleration.

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