Automobile liftgate plate door torsion opener

Abstract

A torsion opening and closing device for an automobile liftgate plate door is disclosed. The torsion opening and closing device for an automobile liftgate plate door according to an embodiment of the present invention is a torsion opening and closing device that provides elastic restoring force to the opening and closing operation of a plate door constituting a liftgate mounted at the rear end of an automobile cargo compartment, and comprises: a torsion bar structure mounted on the outer side of the plate door adjacent to the hinge axis of the plate door and extended in a horizontal direction on both sides by a length corresponding to the width of the plate door, having a bent portion formed that abuts the outer side of the plate door, and a structure that generates elastic restoring force by twisting due to the opening operation of the plate door and provides the generated elastic restoring force to the closing operation of the plate door through the bent portion; and a torsion bar fixing portion that fixes the position of both ends of the torsion providing portion. The gist of the configuration is to include a torsion strength variable member that is mounted on the outer side of the plate door and is mounted adjacent to the bent portion of the torsion providing member, and has a structure that changes the magnitude of the elastic restoring force generated from the torsion providing member by changing the spacing between the bent portion and the outer side of the plate door.

Description

Technology Field

[0001] The present invention relates to an automobile lift gate opening and closing device, and more specifically, to an automobile lift gate plate door torsion opening and closing device that includes a configuration to help easily close the plate door of an automobile lift gate. Background Technology

[0002] Lift gate structures widely used in the automotive freight transport sector adopt a design equipped with plate doors to prevent goods from falling out during the loading and unloading process. These plate doors are generally formed from thick metal plates to withstand external impacts, load pressure, and vibrations during driving, and are typically manufactured with the addition of reinforcing ribs and frames to ensure structural rigidity. Due to these structural characteristics, the weight of the plate door increases, and there is a problem of significant physical strain in environments where users must perform manual opening and closing operations.

[0003] In logistics sites, work environments involving the repetitive loading and unloading of cargo are common, and workers are placed in situations where they must repeatedly open and close plate doors within a short period of time. If the plate door is heavy, force is required to lift it when opening, and control is needed to stably lower it when closing. Such repetitive, heavy-duty opening and closing operations drastically increase worker fatigue and lead to a problem where the risk of musculoskeletal disorders increases during prolonged work.

[0004] In particular, plate doors in refrigerated and frozen cargo trucks, industrial equipment transport vehicles, and construction material transport vehicles tend to be designed to be thicker and more robust to ensure cargo protection and structural safety. This increase in weight acts as a factor that further increases the force required for opening and closing the doors, and becomes a practical work obstacle for users with relatively less physical strength, such as the elderly or female workers, by making door operation difficult.

[0005] In conventional lift gate structures, gas springs, hydraulic dampers, or auxiliary hinge structures are applied to improve the convenience of opening and closing plate doors. However, gas spring systems have inconsistent operating characteristics due to pressure changes caused by temperature variations, and there is a problem where the auxiliary force decreases rapidly in low-temperature environments. Additionally, hydraulic systems have the disadvantage of complex structures and increased maintenance costs, and there is a possibility of oil leakage and performance degradation during long-term use.

[0006] In addition, while structures equipped with gas springs or hydraulic assists may be effective for assisting in opening the door, users often have to apply additional force to fully seal the door during the closing operation. This makes it difficult to ensure a completely sealed state when the door is closed and can lead to problems such as the door developing play or causing noise due to vibrations while driving.

[0007] In conventional technology, approaches such as applying lightweight materials or attempting structural weight reduction have been proposed to decrease door weight. However, since structural requirements for cargo protection and resistance to external impacts must be satisfied, there are limitations to achieving weight reduction while maintaining sufficient rigidity. Consequently, relying solely on door weight reduction to ensure ease of opening and closing is not a practical solution.

[0008] In addition, due to the structural characteristics of the lift gate door being located at the lower rear of the vehicle, it is continuously exposed to external contaminants, moisture, dust, and road conditions. This can lead to problems such as increased friction in the hinge structure, corrosion, and increased rotational resistance. This increased frictional resistance acts as a factor that further increases the force required to open and close the door. As vehicles are used for longer periods, the opening and closing resistance increases, resulting in a problem where user convenience is continuously degraded.

[0009] In logistics work sites, the prevention of safety accidents is also considered an important factor. There is a risk of accidents where a worker's hands or body parts are pinched if a heavy plate door suddenly falls while open or descends at an excessive speed during the closing process. In conventional structures, there are cases where such risks are not sufficiently controlled, and the inability to provide stable control during opening and closing operations is pointed out as a safety issue.

[0010] Furthermore, in various cargo transportation environments, the requirements for door opening and closing assistance force may vary depending on the weight of the cargo, the operator's working method, and the purpose of vehicle use. However, most assistance devices based on conventional technology are designed to provide a fixed assistance force, making it difficult to adjust them to suit the user environment. Consequently, problems arise where the assistance force is insufficient in some environments, while in others, excessive assistance force actually degrades door operability.

[0011] As such, conventional automobile lift gate plate door structures contain various problems, such as the burden of opening and closing operations due to increased door weight, musculoskeletal risks due to repetitive work, environmental dependence of auxiliary devices, lack of closing stability, maintenance issues, risk of safety accidents, and lack of adaptability to the user environment. There has been a continuous need for a structure that solves these problems of the conventional technology, enables smooth opening and closing operations with minimal force, ensures stability in the closed state, and allows for the adjustment of elastic auxiliary force according to the user environment, and the present invention aims to solve the problems of the conventional technology. Prior art literature

[0012] Korean Patent Publication No. 10-2108259 (Registration Date: April 29, 2020) The problem to be solved

[0013] Conventional plate doors installed in automobile lift gates are often manufactured with thick and heavy structures to prevent cargo from falling out and to ensure structural rigidity, which presents a problem in that significant force is required when users perform opening and closing operations. In environments involving repetitive cargo loading and unloading, this burden of opening and closing can increase work fatigue and cause musculoskeletal strain; furthermore, maintaining a stable seal during the closing process is difficult, raising concerns about play and noise occurring while driving. Additionally, conventional auxiliary devices have limitations in that the auxiliary force is inconsistent or difficult to adjust depending on environmental changes or usage conditions. Therefore, it is required to provide a structure that enables smooth operation with minimal force during the opening and closing of the plate door, maintains a stable closed state, and allows for the adjustment of elastic auxiliary force according to the usage environment. means of solving the problem

[0014] A torsion opening and closing device for an automobile liftgate plate door according to one aspect of the present invention for achieving such an objective is a torsion opening and closing device that provides elastic restoring force to the opening and closing operation of a plate door constituting a liftgate mounted at the rear end of an automobile cargo compartment, and comprises: a torsion providing part having a structure that is mounted on the outer side of the plate door adjacent to the hinge axis of the plate door and extends horizontally in both directions by a length corresponding to the width of the plate door, has a bent portion formed that contacts the outer side of the plate door, generates elastic restoring force by twisting due to the opening operation of the plate door, and provides the generated elastic restoring force to the closing operation of the plate door through the bent portion; and a torsion bar fixing part that fixes the position of both ends of the torsion providing part. The configuration may include a torsion strength variable member having a structure that is mounted on the outer side of the plate door and adjacent to the bent portion of the torsion providing member, and changes the magnitude of the elastic restoring force generated from the torsion providing member by changing the spacing between the bent portion and the outer side of the plate door.

[0015] In one embodiment of the present invention, the torsion providing member may comprise: a horizontal extension member mounted on the outer side of the plate door adjacent to the hinge axis of the plate door and extended in a horizontal direction on both sides by a length corresponding to the width of the plate door; a bending member formed on the horizontal extension member and having a structure bent upward in a U-shape to a predetermined height, and having a structure that contacts the outer side of the plate door to twist the horizontal extension member in opposition to the opening operation of the plate door; and a bending fixing member formed at the other end of the horizontal extension member and bent vertically upward to extend by a predetermined length.

[0016] In one embodiment of the present invention, the torsion bar fixing part may be configured to include: a fixing bushing mounted on one side of a lift gate unrelated to the opening and closing operation of a plate door, which is connected to one end of the horizontal extension part of the torsion providing part by a hinge structure that is rotatable in place; and a fixing stopper that restrains and fixes the bending fixing part of the torsion providing part to one side of the lift gate unrelated to the opening and closing operation of the plate door.

[0017] In one embodiment of the present invention, the variable torsion strength may comprise: a torsion adjustment bracket having a structure in which an inclined surface is formed that contacts the bent portion of the torsion providing portion and is repositioned upward to expand the gap between the bent portion and the outer side of the plate door; a torsion adjustment bolt mounted on the outer side of the plate door and having a structure that changes the position of the torsion adjustment bracket up and down and changes the position of the torsion adjustment bracket by a bolting operation; and a fixing bracket mounted on the outer side of the plate door and having a structure that restrains the lateral repositioning of the bent portion so that the position of the bent portion of the torsion providing portion is positioned adjacent to the position of the torsion adjustment bracket, while allowing the repositioning of the bent portion and the horizontal extension portion in the twisting direction. Effects of the invention

[0018] The torsion opening and closing device for an automobile liftgate plate door according to the present invention enables a user to perform door opening and closing operations with minimal force by having a torsion providing part positioned adjacent to the hinge axis of the plate door accumulate torsional elastic force during opening and provide elastic restoring force in the closing direction. Accordingly, it is possible to significantly reduce the physical burden on the worker during repetitive cargo loading and unloading operations and improve work efficiency. In addition, by adjusting the gap between the bending part and the outer surface of the door through a variable torsion strength part, the elastic assist force can be adjusted according to the door weight or operating environment, thereby enabling optimal opening and closing sensitivity under various operating conditions. Furthermore, it provides stable sealing force during the closing process, preventing play and noise during driving and improving the stability of the door. It has the advantage of reducing the burden of maintenance due to its simple structure and excellent durability, and maintaining relatively stable performance even under changes in the external environment. Brief explanation of the drawing

[0019] FIG. 1 is a perspective view showing a torsion opening and closing device for an automobile liftgate plate door according to one embodiment of the present invention. Figure 2 is an enlarged view of section A of Figure 1. Figure 3 is an enlarged view of section B of Figure 1. FIG. 4 is a side view showing a torsion opening and closing device for an automobile liftgate plate door according to one embodiment of the present invention, showing how the magnitude of the elastic restoring force is changed using a variable torsion strength part. Specific details for implementing the invention

[0020] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention.

[0021] Throughout this specification, when it is stated that one component is located "on" another component, this includes not only cases where one component is in contact with another component, but also cases where another component exists between the two components. Throughout this specification, when it is stated that a part "includes" a component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0022] FIG. 1 shows a perspective view of an automobile liftgate plate door torsion opening / closing device according to one embodiment of the present invention, FIG. 2 and FIG. 3 show enlarged views of part A and part B of FIG. 1, respectively, and FIG. 4 shows a side view of an automobile liftgate plate door torsion opening / closing device according to one embodiment of the present invention.

[0023] Referring to these drawings, the automobile lift gate plate door torsion opening / closing device (100) according to the present embodiment is provided with a torsion providing part (110) of a specific structure, a torsion bar fixing part (120), and a torsion strength variable part (130), thereby enabling the user to easily perform the opening / closing operation with minimal force and to stably maintain the closed state when the plate door mounted on the automobile lift gate is opened / closed.

[0024] Hereinafter, with reference to FIGS. 1 to 4, each component constituting the automobile lift gate plate door torsion opening / closing device (100) according to the present embodiment will be described in detail.

[0025] Detailed description of the torsion providing part (110)

[0026] The torsion providing member (110) is a key component positioned adjacent to the hinge axis of the plate door to generate elastic restoring force through torsional deformation when the door is opened and to provide restoring force in the closing direction. The torsion providing member (110) is formed as a torsion bar structure extending horizontally along the outer side of the plate door to evenly distribute the load in the door width direction and is designed to provide stable elastic reaction force throughout the opening and closing operation.

[0027] The torsion providing part (110) can be formed from high-elasticity spring steel, alloy steel, or heat-treated carbon steel and is designed to maintain a stable restoring force within the elastic limit even under repeated torsional loads. Anti-corrosion coating, galvanizing, or powder coating treatment can be applied to the surface to suppress corrosion and maintain long-term durability even in the rear vehicle structure exposed to the external environment.

[0028] The torsion providing part (110) accumulates torsional stress as the door rotates when the plate door is opened, and when the door moves to the closed position, the accumulated elastic energy acts as a restoring force to assist the closing motion. This elastic assisting force reduces the force required by the user to push the door closed and serves to reduce the accumulation of fatigue in the worker in a repetitive work environment.

[0029] In addition, since the torsion providing part (110) is a structure that utilizes torsional elasticity rather than a simple rotational assisting structure, unlike a gas spring, there is less variation in performance due to changes in temperature or pressure, and there is no risk of leakage or maintenance burden like that of a hydraulic device. Accordingly, stable operating characteristics can be maintained even under various environmental conditions.

[0030] The torsion providing part (110) has a structure in which torsional deformation occurs in the central part while both ends are supported by the torsion bar fixing part, and can be designed so that the elastic force gradually increases in response to changes in the opening and closing angle of the plate door. Such structural characteristics provide smooth movement during the initial opening of the door and provide sufficient sealing force during the closing section, thereby providing the effect of improving door stability.

[0031] Detailed description of the horizontal extension part (111)

[0032] The horizontal extension (111) is a straight extension structure that forms the basic framework of the torsion providing part (110) and is formed with a length corresponding to the width direction of the plate door, serving to effectively distribute torsional elastic force. The horizontal extension (111) is positioned along the outer side of the plate door to provide a uniform elastic reaction force across the entire width of the door, thereby preventing the load from being concentrated at a specific point.

[0033] The horizontal extension (111) can be formed as a round rod, a square cross-section bar, or a flat spring structure, and the cross-sectional shape can be selected considering torsional rigidity and elastic recovery characteristics. A round cross-section provides uniform torsional characteristics, while a square or flat cross-section has the advantage of reinforcing structural rigidity and improving contact stability with the outer surface of the door.

[0034] The horizontal extension (111) acts as a central structure that receives the load transmitted through the bending section when the plate door is opened, causing torsional deformation. At this time, since the magnitude of the torsional elastic force generated is determined by the length, diameter, and material characteristics of the horizontal extension (111), it is possible to design it to suit the door weight and usage conditions.

[0035] In addition, the horizontal extension (111) is stably supported through both ends that are coupled to the torsion bar fixing part, and is linked with a hinge structure that acts as a rotational center axis to allow torsional deformation to occur smoothly. This structure can be designed to minimize structural deformation or fatigue failure even during repeated opening and closing operations.

[0036] The horizontal extension (111) may be applied together with a reinforcing rib structure or a protective cover to prevent deformation caused by external impact or contact during operation, and may be formed with a slim structure to ensure harmony with the vehicle's exterior. This allows for the simultaneous securing of functionality and exterior finish.

[0037] Detailed description of the bending part (112)

[0038] The bent portion (112) is formed as a structure bent upward in one area of ​​the horizontal extension portion (111) and performs the function of transmitting the load resulting from the door opening and closing operation to the torsion providing portion (110) while in direct contact with the outer side of the plate door. The bent portion (112) is formed as a U-shape or a curved bent structure and is designed to stably contact the door surface.

[0039] The bending portion (112) forms a point of action that induces torsional deformation in the horizontal extension as it is pushed by the outer surface of the door when the plate door is opened. Through this point of action structure, torsional stress gradually increases with the change in the door opening angle, and a torsion operating mechanism is implemented in which a restoring force is generated in the closing direction.

[0040] A synthetic resin pad, an anti-wear coating, or a rubber cushioning material for friction reduction may be attached to the contact surface of the bent portion (112) to prevent damage to the door surface and provide the effect of reducing noise during operation. In addition, the shape of the contact surface may be curved to relieve local pressure and be designed to maintain a stable contact state.

[0041] The height and bending angle of the bending portion (112) are designed considering the interaction with the torsion strength variable portion, and can be configured so that the amount of twisting of the torsion providing portion changes according to the change in the gap between the bending portion and the outer surface of the door. Through this, it is possible to adjust the elastic auxiliary force according to the user environment or the weight of the door.

[0042] Since the bent portion (112) is a region where repetitive contact loads and torsional action are concentrated, a curvature design and heat treatment process considering fatigue strength can be applied. This structural reinforcement design suppresses deformation or cracking even in a long-term usage environment and allows stable torsional action to be continuously maintained.

[0043] Detailed explanation of the bending fixing part (113)

[0044] The bending fixing part (113) is a structure formed by bending vertically upward from the other end of the horizontal extension part (111), and is a component that provides support and fixing functions so that the torsion providing part (110) acts as a reference point when subjected to torsional deformation. The bending fixing part (113) is designed to maintain a relative position with respect to the structure of the lift gate, thereby forming a reference support point that allows the torsion providing part (110) to stably perform torsional action.

[0045] The bending fixing part (113) acts as a fixed point where rotation and deformation are restricted through a bending structure extended in the vertical direction, and functions to structurally transmit torsional stress generated in the horizontal extension part (111) to the support part. This structure effectively disperses the reaction force generated during torsion action and contributes to preventing stress concentration in specific areas.

[0046] The bending fixing part (113) may be formed as a metal bending structure having sufficient thickness to ensure rigidity, and a reinforcing flange, rib, or curved bending shape may be additionally applied to increase structural stability. In addition, a bolt fastening hole or an insertion coupling structure may be formed to ensure fastening stability with the vehicle structure.

[0047] The bending fixing part (113) does not perform direct rotational movement with the opening and closing operation of the plate door, and acts as a reference point that stably maintains the torsion axis of the torsion providing part. This fixed reference point formation structure prevents structural distortion or positional displacement while the torsion providing part performs repetitive torsion action, thereby enabling stable operation for a long period of time.

[0048] The bending fixing part (113) can be designed so that structural deformation does not occur even in environments of external impact, vibration, and long-term repetitive loading, and surface treatment for rust prevention and improved durability can be applied. Through this, stable support function can be continuously maintained even in harsh environments at the rear lower part of the vehicle.

[0049] Detailed description of the torsion bar fixing part (120)

[0050] The torsion bar fixing part (120) is a structural support component that stably supports the positions of both ends of the torsion providing part (110) and forms a rotation reference to ensure smooth torsional elastic action. The torsion bar fixing part (120) is mounted on the side of the structure of the lift gate to form a fixed support point independent of the opening and closing operation of the plate door.

[0051] The torsion bar fixing part (120) enables efficient torsion action through structural characteristics that rotatably support one end of the torsion providing part (110) while fixing and restraining the other end. This support method forms a base structure that generates stable elastic restoring force by allowing the torsion bar to act as a torsion spring.

[0052] The torsion bar fixing part (120) can be formed as a metal bracket structure with excellent rigidity and can be firmly mounted to a lift gate frame or reinforcing structure by bolt fastening or welding. Such a fixing structure minimizes vibration or play caused by torsional reaction force and maintains positional stability even during long-term use.

[0053] Additionally, the torsion bar fixing part (120) may include an alignment reference plane and a position guide structure to maintain installation precision, and may perform the function of guiding the torsion providing part to be placed in an accurate position during assembly. This structure contributes to ensuring uniformity of torsion action and improving the smoothness of opening and closing movements.

[0054] The torsion bar fixing part (120) is designed with a structure that takes into account durability to withstand vibrations, shocks, and repetitive loads that occur during vehicle operation, and may be subjected to anti-corrosion coating and environmentally resistant surface treatment. This allows for stable support functions to be maintained in various operating environments and ensures reliable operation for a long period.

[0055] Detailed description of the fixed bushing (121)

[0056] The fixed bushing (121) is a hinge connection structure that rotatably supports one end of the horizontal extension (111) of the torsion providing part (110), and serves to provide smooth rotational support while minimizing friction while the torsion providing part performs a twisting action. The fixed bushing (121) is mounted on the lift gate structure and serves as the rotational center axis of the torsion bar.

[0057] The fixed bushing (121) can be formed with a structure combining a metal sleeve and a low-friction synthetic resin liner, and can be designed to reduce rotational friction and minimize wear by using polyacetal (POM), nylon, or PTFE-based materials. This material composition is advantageous for maintaining smooth rotational performance for a long period without lubrication maintenance.

[0058] The fixed bushing (121) serves to increase the efficiency of elastic restoring force transmission by minimizing rotational resistance when the torsion providing part (110) performs a torsional action. As rotational resistance is reduced, the operating sensitivity during door opening and closing becomes smoother, and the operating force perceived by the user is reduced.

[0059] Additionally, the fixed bushing (121) may be applied with a sealing structure or protective cap to prevent the entry of external dust, moisture, and contaminants, and may be designed to maintain internal lubrication for a long period. This contributes to preventing corrosion and increased friction problems that may occur in the rear underside environment of the vehicle.

[0060] The fixed bushing (121) is designed to maintain wear resistance and dimensional stability even under repetitive rotational loads and vibration environments, and can be applied as a modular structure that is easy to replace as needed. These structural characteristics improve ease of maintenance and contribute to maintaining stable operating performance over a long period.

[0061] Detailed description of the fixed stopper (122)

[0062] The fixed stopper (122) is a fixed support component that restrains the position of the bending fixing part (113) relative to the side of the lift gate structure, thereby maintaining a reference position while the torsion providing part (110) performs a twisting action. The fixed stopper (122) is mounted on the side structure of the lift gate, which is independent of the opening and closing operation of the plate door, and serves to stably fix one point of the torsion providing part.

[0063] The fixed stopper (122) functions to prevent the torsional axis of the torsion providing part (110) from being displaced by restricting the vertical and horizontal movement of the bending fixing part (113). Through this, the reaction force and vibration generated during torsion action are uniformly distributed throughout the entire structure, and the phenomenon of stress concentration at a specific joint can be prevented.

[0064] The fixed stopper (122) may be formed as a metal bracket or block structure with high rigidity and may include a groove shape or support surface structure into which the bent fixing part (113) is inserted or closely attached. Such a structure increases joint stability and suppresses the occurrence of play even in a repetitive load environment, thereby maintaining a stable support state for a long period of time.

[0065] Additionally, the fixed stopper (122) may be applied in a structure combined with an elastic pad or cushioning member to absorb or disperse vibration and shock loads generated during vehicle operation. This can contribute to reducing noise caused by metal contact between structures and alleviating structural fatigue.

[0066] The fixed stopper (122) may include a position guide surface or an alignment reference surface to maintain installation precision, and guides the bent fixing part (113) to be fixed in the correct position during assembly. These structural features contribute to increasing the operational reliability of the torsion providing part and ensuring consistent elastic action even during repeated opening and closing movements.

[0067] Detailed description of the torsion strength variable part (130)

[0068] The torsion strength variable section (130) is an adjustment structure that allows the magnitude of the elastic restoring force generated in the torsion providing section (110) to be adjusted, and performs the function of adjusting the amount of torsional deformation by changing the gap between the bending section (112) and the outer side of the plate door. Through this, an optimal auxiliary force suitable for the door weight and usage environment can be set.

[0069] The torsion strength variable part (130) operates on the principle of changing the initial deformation state of the torsion providing part by adjusting the position where the bending part (112) contacts when the door is opened, and thereby changing the magnitude of the elastic reaction force generated when the door is opened and closed. This adjustment function allows the opening and closing sensitivity to be optimized in response to user conditions or changes in the working environment.

[0070] The torsion strength variable part (130) is formed in a structure that is mounted on the outer side of the plate door, allowing for relatively easy adjustment from the outside, and its position can be changed through bolt fastening or sliding adjustment methods. This structure makes maintenance and setting changes easy, thereby increasing responsiveness to various operating environments.

[0071] Additionally, the torsion strength variable part (130) can be designed to have sufficient structural rigidity so that deformation or displacement does not occur even with repeated load transfer, and a locking structure or friction fixing structure can be applied together so that the position is stably maintained after adjustment.

[0072] The torsion strength variable part (130) can reset the auxiliary force in response to changes in opening and closing resistance due to increased door weight, increased hinge friction, or aging, thereby providing a functional advantage of maintaining opening and closing convenience similar to the initial state even in a long-term usage environment.

[0073] Detailed description of the torsion adjustment bracket (131)

[0074] The torsion adjustment bracket (131) is a core component of the torsion strength variable part (130) and forms an inclined surface structure that contacts the bent part (112), thereby changing the gap between the bent part and the outer side of the plate door. Through the inclined surface structure, the contact position of the bent part gradually changes, and the amount of twisting of the torsion providing part is adjusted.

[0075] The torsion adjustment bracket (131) is installed to allow for vertical movement, and as it moves upward, the gap between the bending part (112) and the outer surface of the door widens, increasing the initial twisting amount of the torsion providing part and consequently increasing the closing direction restoring force. Conversely, in the downward position, the elastic assist force is reduced, allowing for smoother opening and closing sensitivity.

[0076] The torsion adjustment bracket (131) may be formed of a high-strength metal material, and a friction-reducing coating or a wear-resistant pad may be applied to the inclined surface contact portion. This configuration can provide the effect of reducing wear caused by repeated contact with the bending portion and reducing noise during operation.

[0077] Additionally, the torsion adjustment bracket (131) is linked with the torsion adjustment bolt to secure its position, and is designed to ensure sufficient fastening strength so that its position does not change even with external vibration or impact after adjustment. If necessary, a scale mark or a reference position mark may be applied to allow the adjustment status to be checked intuitively.

[0078] The torsion adjustment bracket (131) is designed to stably guide the contact position of the bending part (112) without hindering the movement in the twisting direction, thereby effectively performing the auxiliary force adjustment function while maintaining the operating characteristics of the torsion supply part. This structure plays an important role in achieving optimal opening and closing performance under various operating conditions and improving user convenience.

[0079] Detailed description of the torsion adjustment bolt (132)

[0080] The torsion adjustment bolt (132) is an adjustment driving element that adjusts the upper and lower position of the torsion adjustment bracket (131) to change the gap between the bending part (112) and the outer side of the plate door, and thereby sets the magnitude of the elastic restoring force generated by the torsion providing part (110). The torsion adjustment bolt (132) performs the function of precisely moving the position of the bracket through a screw coupling structure mounted on the outer side of the plate door.

[0081] The torsion adjustment bolt (132) can be designed so that the torsion adjustment bracket (131) moves up and down in fine increments when rotated at a predetermined angle through a linear movement principle using screw threads. This structure enables fine adjustment of the elastic auxiliary force, thereby allowing for detailed settings tailored to the door weight, working environment, and user preference.

[0082] The torsion adjustment bolt (132) can be formed from high-strength carbon steel or alloy steel and designed so that no deformation or loosening occurs even under repetitive loads and vibration environments, and may be galvanized or anti-corrosion coated to prevent corrosion. In addition, it can be manufactured with a structure that takes into account durability to maintain fastening strength even in long-term use environments.

[0083] The torsion adjustment bolt (132) may be equipped with a spring washer, a nylon insert nut, or a double locking structure to prevent loosening due to vibration, and may be configured to secure sufficient frictional fixing force to maintain the set position after adjustment. This ensures that the set torsion strength does not change even in vibration or shock environments that occur during vehicle operation.

[0084] The torsion adjustment bolt (132) can be formed with a head shape that can be easily adjusted using a tool from the outside, such as a hexagonal bolt, a socket bolt, or a handle-type adjustment knob, and can be positioned with consideration for accessibility during maintenance. This structure provides the effect of improving operational convenience by allowing a field worker to easily reset the torsion strength.

[0085] Detailed description of the fixed bracket (133)

[0086] The fixed bracket (133) is a position restraint component that stably maintains the lateral position of the bent portion (112) to ensure that the contact position with the torsion adjustment bracket (131) is maintained at a constant level. The fixed bracket (133) is mounted on the outer side of the plate door and performs a structural function that restricts the movement of the bent portion in the left and right directions while allowing movement in the twisting direction.

[0087] The fixed bracket (133) guides the bent portion (112) to contact the torsion adjustment bracket (131) at an accurate position, thereby ensuring that the elastic action of the torsion providing portion (110) is stable. This position-maintaining function plays an important role in maintaining consistency in the elastic auxiliary force by ensuring that the contact position does not change even during repeated opening and closing movements.

[0088] The fixed bracket (133) can be formed as a guide structure that surrounds or supports the bent portion (112) from both sides, and can be designed to suppress lateral movement while having a sufficient gap so as not to hinder the torsional movement of the bent portion. This structure contributes to securing positional stability while maintaining the degree of freedom of torsion action.

[0089] The fixed bracket (133) can be formed from a high-strength metal material and designed so that no deformation occurs even under repetitive contact loads and vibration environments, and a synthetic resin liner or wear-resistant pad for reducing friction can be applied to the contact portion. This can reduce operating noise and minimize wear on the contact portion.

[0090] The fixed bracket (133) guides the bent portion (112) to be positioned in the correct location through an alignment reference plane and a position guide structure during assembly, and is securely fastened so that it does not deviate from its position even during long-term use. These structural characteristics increase the operational reliability of the torsion providing portion and contribute to maintaining stable opening and closing assistance performance in various operating environments.

[0091] As explained above, the torsion opening and closing device for an automobile liftgate plate door according to the present invention has the effect of improving the burden of the conventional structure in which a user must directly lift or push to close a heavy plate door. By having a torsion providing part positioned adjacent to the hinge axis accumulate torsional elastic force when the door is opened and provide a restoring force in the closing direction, the user can perform the opening and closing operation with less force, and the physical burden is significantly reduced even in a repetitive work environment.

[0092] In conventional environments where workers must continuously open and close doors during the repetitive process of loading and unloading cargo, accumulated fatigue and musculoskeletal strain have been identified as problems. The present invention is configured so that elastic energy accumulated upon opening the door assists the closing motion, thereby alleviating the burden of the work motion and contributing to a reduction in worker fatigue and improved work continuity. This leads to substantial improvements in work efficiency at logistics sites.

[0093] Unlike conventional gas springs or hydraulic auxiliary devices, which suffer from inconsistent performance or increased maintenance burdens due to temperature, leakage, or pressure fluctuations, the present invention minimizes performance deviations caused by changes in the external environment by adopting a structure that utilizes the torsional elasticity of a torsion bar. It has the advantage of maintaining stable auxiliary force even in long-term usage environments due to its simple structure and excellent mechanical durability.

[0094] Conventional problems such as play or noise occurring during driving due to insufficient sealing force during the door closing process can also be improved. The elastic restoring force of the present invention acts continuously when the door reaches the closed position to stably maintain a sealing state, and prevents the door from shaking or creating a gap even in a vibrating environment, thereby improving vehicle driving stability and quietness.

[0095] Furthermore, the present invention allows for the adjustment of the magnitude of the elastic restoring force generated by the torsion providing unit by controlling the gap between the bending unit and the outer surface of the door through a variable torsion strength unit. Accordingly, optimal auxiliary force can be set according to door weight, vehicle structure, user working environment, and operating conditions, thereby effectively improving the limitations of the application range of conventional fixed auxiliary force structures.

[0096] Even in environments where the plate door is located at the lower rear of the vehicle and exposed to dust, moisture, and contaminants, the structure of the present invention can effectively compensate for the difficulty of opening and closing caused by increased hinge rotational resistance. The restoring force provided by the torsion providing part offsets the increased opening and closing resistance, allowing the opening and closing sensitivity to be maintained similar to that of the initial state even after long-term use, and has the effect of preventing a decrease in ease of use.

[0097] In addition, it has the effect of improving safety by mitigating the phenomenon of the door rapidly falling or closing at an excessive speed during opening and closing operations, thereby reducing the risk of pinching accidents for workers. Since the movement of the door is cushioned by elastic restoring force and induced to close at a controlled speed, the safety of the working environment is improved, and as a result, it has the effect of comprehensively improving the work burden, maintenance issues, environmental dependence, and safety issues raised in conventional technology.

[0098] The above detailed description of the present invention describes only specific embodiments thereof. However, it should be understood that the present invention is not limited to the specific forms mentioned in the detailed description, but rather should be understood to include all variations, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims.

[0099] In other words, the present invention is not limited to the specific embodiments and descriptions described above, and any person skilled in the art to which the present invention pertains can make various modifications without departing from the essence of the invention as claimed in the claims, and such modifications fall within the scope of protection of the present invention. Explanation of the symbols

[0100] 100: Automotive liftgate plate door torsion opening / closing device 110: Torsion providing unit 111: Horizontal extension part 112: Bending part 113: Bending fixing part 120: Torsion bar fixing part 121: Fixed bushing 122: Fixed stopper 130: Variable torsion strength section 131: Torsion adjustment bracket 132: Torsion adjustment bolt 133: Fixing bracket 10: Plate door

Claims

Claim 1 A torsion opening / closing device that provides elastic restoring force to the opening and closing operation of a plate door constituting a lift gate mounted at the rear end of a vehicle cargo compartment, comprising: a torsion bar structure mounted on the outer side of the plate door adjacent to the hinge axis of the plate door and extended in a horizontal direction on both sides by a length corresponding to the width of the plate door, wherein a bent portion (112) is formed that contacts the outer side of the plate door, and is twisted by the opening operation of the plate door to generate elastic restoring force, and provides the generated elastic restoring force to the closing operation of the plate door through the bent portion (112); and a torsion bar fixing portion (120) that fixes the position of both ends of the torsion providing portion (110). and a torsion strength variable part (130) having a structure that is mounted on the outer side of the plate door and is mounted adjacent to the bent part (112) of the torsion providing part (110), and changes the magnitude of the elastic restoring force generated from the torsion providing part (110) by changing the spacing between the bent part (112) and the outer side of the plate door; wherein the torsion providing part (110) comprises: a horizontal extension part (111) which is mounted on the outer side of the plate door adjacent to the hinge axis of the plate door and extends in a horizontal direction on both sides by a length corresponding to the width of the plate door; and a bent part (112) which is formed on the horizontal extension part (111), has a structure that is bent upward in a U-shape by a predetermined height, and is in contact with the outer side of the plate door to twist the horizontal extension part (111) in opposition to the opening operation of the plate door. and a bent fixing part (113) formed at the other end of the horizontal extension part (111) and bent vertically upward to extend by a predetermined length; wherein the torsion bar fixing part (120) includes: a fixing bushing (121) mounted on one side of a lift gate unrelated to the opening and closing operation of the plate door, which is connected to one end of the horizontal extension part (111) of the torsion providing part (110) by a hinge structure that allows rotation in place; and a fixing stopper (122) that restrains and fixes the bent fixing part (113) of the torsion providing part (110) to one side of the lift gate unrelated to the opening and closing operation of the plate door.The torsion strength variable part (130) includes a torsion adjustment bracket (131) having a structure in which an inclined surface is formed that contacts the bent part (112) of the torsion providing part (110) and is positioned upward to expand the gap between the bent part (112) and the outer side of the plate door; and a torsion adjustment bolt (132) mounted on the outer side of the plate door, having a structure that changes the position of the torsion adjustment bracket (131) up and down, and changes the position of the torsion adjustment bracket (131) by a bolting fastening operation. A torsion opening / closing device for an automobile liftgate plate door, characterized by including: a fixing bracket (133) which is mounted on the outer side of the plate door and has a structure that restricts the lateral position change of the bending part (112) so that the position of the bending part (112) of the torsion providing part (110) is positioned adjacent to the position of the torsion adjustment bracket (131), and allows the position change in the twisting direction of the bending part (112) and the horizontal extension part (111). Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete

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