Anti-sagging control method and control system for suspended door

Abstract

The invention relates to the technical field of door body control, in particular to an anti-sagging control method and a control system for a suspended door, which are characterized in that whether a door row meets a support triggering condition or not is judged by acquiring a suspended door operation state signal and a door row extension state signal, and support wheels are controlled to be unfolded to support the bottom of the door row when the condition is met; and when the conditions are not met, the supporting wheels are controlled to be stored. According to the method, unfolding and folding of the supporting wheels can be coordinated and matched with the operation process of the suspended door to form closed-loop control, so that drooping of the door row is effectively inhibited on the premise that the weight of the door row structure is not remarkably increased, and the operation stability and reliability of the suspended door are improved.

Description

Technical Field

[0001] This invention relates to the field of door control technology, and in particular to a method and control system for preventing sagging of a suspended door. Background Technology

[0002] Suspended gates are widely used in industrial parks, factory entrances and municipal passages because they do not require a ground track, are highly adaptable to ground conditions, and have a clean overall appearance. Existing suspended gates typically use load-bearing roller assemblies installed in columns or a gantry frame to provide cantilever support for the gate, allowing it to move horizontally during opening and closing.

[0003] However, as the application scenarios of suspended gates expand, the length and overall weight of the gate panels continue to increase. When the gate panel extends outwards significantly during closing, the front end of the panel is prone to sagging or slight tilting under its own weight. This sagging issue not only affects the appearance and user experience of the suspended gate but also easily leads to increased operating resistance, increased drive load, and even abnormal stress on the load-bearing wheel assembly, thus affecting the long-term operational stability of the suspended gate.

[0004] To address the aforementioned issues, existing technologies typically improve the rigidity of the gate structure by increasing its stiffness, such as thickening the gate profiles, adding reinforcing ribs, or installing fixed support components inside the gate. However, these methods primarily rely on passively enhancing structural strength, which significantly increases the overall weight of the gate and burdens the drive system. Furthermore, they are difficult to dynamically adjust based on changes in the gate's operating status and extension length, and thus cannot effectively suppress gate sagging under specific operating conditions.

[0005] In addition, some technical solutions attempt to install auxiliary support wheels at the bottom of the gate, allowing the gate to contact the ground at a specific position to share some of the weight. However, existing auxiliary support wheels mostly adopt fixed or simple flip-up structures, and their deployment and retraction usually rely on manual operation or simple mechanical linkage. They lack an active control mechanism based on the operating status of the cantilever gate and the extension status of the gate, which can easily lead to problems such as unreasonable timing of support wheel deployment, untimely retraction, or interference with the operation of the gate body. It is difficult to meet the stability and reliability requirements of the cantilever gate at different operating stages.

[0006] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0007] The purpose of this invention is to provide a method and control system for preventing sagging of a cantilever gate, addressing the shortcomings of existing technologies. The aim is to make judgments based on the operating state and the extension state of the gate, and to coordinate the deployment and retraction of the support wheels, so as to improve the stability of the cantilever gate during operation without significantly increasing the weight of the gate structure.

[0008] This invention achieves the above-mentioned objective through the following technical solution: a method for controlling the sagging of a suspended door, applied to a suspended door including a bottom beam, wherein a support wheel mechanism is provided on the bottom beam, the support wheel mechanism including a mounting base and a ball screw structure thereon, a crank rod connected to the ball screw, a connecting rod fixed to the crank rod at a fixed angle, a pull rod with both ends hinged to the mounting base and the connecting rod respectively, and a support wheel installed at the end of the connecting rod; the method includes the following steps: Operation acquisition steps: The operation status acquisition component acquires the floating door operation status signal and the door extension status signal and sends them to the control processing component; Condition judgment step: The control processing component determines the support triggering condition based on the suspended door operation status signal and the door extension status signal and outputs the trigger judgment signal; Deployment command steps: When the trigger judgment signal is true, the control processing component sends the support wheel deployment control command to the execution drive component; The support wheel deployment process is as follows: The drive assembly drives the ball screw motor of the ball screw structure to move the ball components of the ball screw structure, and through the linkage of the crank, connecting rod, and tie rod, the support wheel contacts the ground. Status feedback step: The support wheel status detection unit acquires the support wheel status signal and feeds it back to the control processing component; Storage instruction steps: When the trigger judgment signal is false or the floating door operation status signal indicates that the floating door is in the open operation state, the control processing component sends the support wheel storage control instruction to the execution drive component; Support wheel storage steps: The drive assembly reverses the drive of the ball screw structure to move the ball components, causing the support wheel to lift off the ground.

[0009] Furthermore, the operation acquisition steps are as follows: the door status detection unit outputs the suspended door opening status signal or the suspended door closing status signal as the suspended door operation status signal, and the door displacement detection unit outputs the door extension length signal as the door extension status signal. The support triggering conditions in the condition judgment step include the gate extension length reaching or exceeding a preset threshold; The supporting triggering conditions in the condition judgment step include simultaneously satisfying the door extension length reaching or exceeding a preset threshold and the suspended door operation status signal indicating that the suspended door is in a closed operation state.

[0010] Furthermore, the process between the acquisition step and the conditional judgment step also includes: Phase identification step: The control processing component generates an operating phase signal based on the rate of change of the gate extension status signal and inputs the operating phase signal into the condition judgment step. The condition judgment step only performs the judgment on the support triggering condition when the operating phase signal indicates that the suspended gate is in a uniform speed operation phase or a deceleration operation phase. Between the conditional judgment step and the instruction expansion step, there is also: Early triggering step: When the gate extension status signal indicates that the gate extension length has entered the preset warning range, the control processing component sends the support wheel deployment control command to the execution drive component in advance, so that the support wheel can be deployed before the gate reaches the maximum extension position.

[0011] Furthermore, the status feedback step is as follows: the support wheel status detection unit outputs the support wheel contact signal with the ground and / or the support wheel limit position signal as the support wheel status signal; The steps following the deployment of the support wheel also include: Complete the judgment step: The control processing component determines whether the support wheel has reached the fully deployed state based on the support wheel status signal.

[0012] Furthermore, the completion determination step also includes the following if the support wheel fails to reach the fully deployed state within a preset time: Abnormal handling steps: The control processing component outputs an abnormal status signal and controls the suspended door to stop operating.

[0013] An anti-sagging control system for a suspended door includes: a support wheel mechanism; an operating status acquisition component; a control processing component; and an execution drive component. The support wheel mechanism is set on the bottom beam of the cantilever gate and includes a mounting base and a ball screw structure. The ball screw structure includes a screw motor, a screw component, a guide rail, and ball components. The ball components are hinged to the crank rod, and the connecting rod is fixed to the crank rod and forms a fixed angle with the crank rod. The mounting base and the connecting rod are respectively hinged at both ends of the pull rod. The support wheel is installed at the end of the connecting rod away from the crank rod and is used to switch between the unfolded state and the retracted state to support the bottom of the gate. The operation status acquisition component is installed on the cantilever gate and includes a gate body status detection unit, a gate displacement detection unit, and a support wheel status detection unit, which are used to output the cantilever gate operation status signal, the gate extension status signal, and the support wheel status signal. The control processing component is installed on the cantilever gate and electrically connected to the operation status acquisition component. It is used to receive the cantilever gate operation status signal, the gate extension status signal and the support wheel status signal, and output the support wheel deployment control command or the support wheel retraction control command. The drive assembly is mounted on the bottom beam of the gate and connected to the control processing assembly and the ball screw structure. It is used to drive the screw motor to drive the support wheel to unfold or retract according to the support wheel unfolding control command or the support wheel retraction control command.

[0014] Furthermore, in the ball screw structure, the ball components are movably mounted on the screw component and guided by the guide rail, so that they can move linearly along the guide rail when the screw motor drives the screw component to rotate. The control processing component is configured to make a joint judgment based on the gate extension length corresponding to the gate extension status signal and the suspended door closing operation status corresponding to the suspended door operation status signal, in order to determine whether to output the support wheel deployment control command. The control processing component is configured to generate an operating phase signal based on the rate of change of the gate extension status signal, and to allow the output of a support wheel deployment control command when the operating phase signal indicates that the cantilever gate is in a constant speed operating phase or a deceleration operating phase.

[0015] Furthermore, the control processing component is configured to output a support wheel deployment control command in advance when the gate extension status signal indicates that the gate extension length has entered a preset warning range; The support roller condition detection unit includes a ground contact detection component and an extreme position detection component, which are used to output the support roller contact signal with the ground and the support roller extreme position signal, respectively.

[0016] Furthermore, the control processing component is configured to output an abnormal status signal and control the suspended gate to stop operating if it does not receive a ground contact signal or a limit position signal from the support wheel status detection unit within a preset time after outputting the support wheel deployment control command; The control processing component is configured to prohibit the output of support wheel deployment control commands when the suspended gate operation status signal indicates that the suspended gate is in the open operation state.

[0017] Furthermore, the drive assembly is configured to output a forward drive signal to the lead screw motor to drive the support wheel to unfold, output a reverse drive signal to the lead screw motor to drive the support wheel to retract, and output a stop drive signal to the lead screw motor when a support wheel limit position signal is received.

[0018] The beneficial effects of this invention are: This method acquires the operating status signals and extension status signals of the cantilever gate during operation, and performs conditional judgments based on these signals. It then controls the deployment and retraction of the support wheels when the gate meets preset support trigger conditions, ensuring that the movement of the support wheels matches the actual operating state of the cantilever gate. This approach avoids malfunctions of the support wheels when no support is needed, improving the rationality and reliability of the support wheel movements from a control logic perspective.

[0019] During the closing process of the suspended gate, when the gate extends outwards to a considerable length, this method can control the support wheels to deploy in a timely manner and make contact with the ground, providing effective support for the front end of the gate. This reduces the sagging or slight tilting of the gate under its own weight, helping to improve the stress state during the closing process and making the suspended gate operate more smoothly. Simultaneously, when the suspended gate enters the open operating state or when the gate no longer requires support, this method can control the support wheels to automatically retract and detach from the ground, thus avoiding interference between the support wheels and the ground or other structures during the gate's opening process and ensuring the smoothness of the suspended gate's opening.

[0020] Furthermore, this method detects the status of the support wheels during or after deployment and feeds the detection results back to the control processing component. This allows the control processing component to make subsequent control decisions based on the actual status of the support wheels, thus forming a closed-loop control process consisting of status acquisition, condition judgment, execution control, and status feedback. This is beneficial for improving the overall stability and operational reliability of the cantilever gate under different operating stages and complex working conditions. By rationally controlling the deployment and retraction processes of the support wheels, this method eliminates the need to passively suppress sagging by increasing the rigidity of the gate structure or adding weight to the gate. It can effectively control gate sagging without significantly increasing the drive load, demonstrating good engineering applicability and promotional value. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure and a magnified schematic diagram of a part of the structure of the present invention.

[0022] Figure 2 for Figure 1 A schematic diagram of the structure after the diagonal tie rod baffle is hidden.

[0023] Figure 3 This is a schematic diagram of the structure of the present invention after partially concealing the bottom beam structure of the door row, as well as an enlarged schematic diagram of a part of the structure.

[0024] Figure 4 This is a structural schematic diagram of one embodiment of the support wheel assembly of the present invention.

[0025] Figure 5 This is a schematic diagram of another embodiment of the support wheel assembly of the present invention.

[0026] Figure 6 This is a schematic diagram of the support wheel mechanism of the present invention.

[0027] Figure 7 This is a schematic diagram of the geometric structure of the support wheel of the present invention when it is in the deployed state.

[0028] Figure 8This is a geometric structural diagram of the intermediate state of the support wheel during the transition from the unfolded state to the retracted state.

[0029] Figure 9 This is a geometric structural diagram of the support wheel of the present invention in its stowed state.

[0030] Figure 10 This is a flowchart of the anti-sagging control method for the suspended door of the present invention. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0032] A method for preventing sagging of a suspended door, see [link to relevant documentation]. Figure 1 and Figure 6 This is applied to a suspended door including a bottom beam 11. The bottom beam 11 is equipped with a support wheel mechanism 4. The support wheel mechanism 4 includes a mounting base 41 and a ball screw structure 411 thereon, a crank rod 42 connected to the ball bearing 411d, a connecting rod 43 fixed to the crank rod 42 at a fixed angle, a pull rod 44 hinged at both ends to the mounting base 41 and the connecting rod 43 respectively, and a support wheel 24 mounted at the end of the connecting rod 43. (See also...) Figure 10 The method includes the following steps: Operation acquisition steps: The operation status acquisition component acquires the floating door operation status signal and the door extension status signal and sends them to the control processing component; Condition judgment step: The control processing component determines the support triggering condition based on the suspended door operation status signal and the door extension status signal and outputs the trigger judgment signal; Deployment command steps: When the trigger judgment signal is true, the control processing component sends the deployment control command of the support wheel 24 to the execution drive component; Support wheel deployment steps: The drive assembly drives the ball screw motor 411a of the ball screw structure 411 to move the ball component 411d of the ball screw structure 411, and through the linkage of the crank 42, connecting rod 43 and pull rod 44, the support wheel 24 contacts the ground. Status feedback step: The status detection unit of support wheel 24 acquires the status signal of support wheel 24 and feeds it back to the control processing component; Storage instruction steps: When the trigger judgment signal is false or the floating door operation status signal indicates that the floating door is in the open operation state, the control processing component sends the support wheel 24 storage control instruction to the execution drive component; Support wheel storage steps: The drive assembly reverses the movement of the ball screw structure 411's ball component 411d to move the support wheel 24 off the ground.

[0033] This method acquires the operating status signals and extension status signals of the cantilever gate during operation, and performs conditional judgments based on these signals. This allows for control of the deployment and retraction of the support wheels 24 when the gate meets preset support trigger conditions, ensuring that the movement of the support wheels 24 matches the actual operating state of the cantilever gate. This approach avoids malfunctions of the support wheels 24 when no support is needed, improving the rationality and reliability of the support wheel 24's actions from a control logic perspective.

[0034] During the closing process of the suspended gate, when the gate extends outwards to a considerable length, this method can control the support wheels 24 to deploy promptly and contact the ground, providing effective support for the front end of the gate. This reduces the sagging or slight tilting of the gate under its own weight, helping to improve the stress state during the closing process and making the suspended gate operate more smoothly. Simultaneously, when the suspended gate enters the open operating state or when the gate no longer requires support, this method can control the support wheels 24 to automatically retract and detach from the ground, thus preventing interference between the support wheels 24 and the ground or other structures during the gate's opening process, ensuring the smoothness of the suspended gate's opening.

[0035] Furthermore, this method detects the state of the support rollers 24 during or after their deployment and feeds the detection results back to the control processing component. This allows the control processing component to make subsequent control decisions based on the actual state of the support rollers 24, thus forming a closed-loop control process consisting of state acquisition, condition judgment, execution control, and state feedback. This is beneficial for improving the overall stability and operational reliability of the suspended gate under different operating stages and complex working conditions. By rationally controlling the deployment and retraction process of the support rollers 24, this method eliminates the need to passively suppress sagging by increasing the rigidity of the gate structure or adding weight to the gate. It can effectively control gate sagging without significantly increasing the drive load, demonstrating good engineering applicability and promotional value.

[0036] Furthermore, the operation acquisition steps are as follows: the door status detection unit outputs the suspended door opening status signal or the suspended door closing status signal as the suspended door operation status signal, and the door displacement detection unit outputs the door extension length signal as the door extension status signal. The support triggering conditions in the condition judgment step include the gate extension length reaching or exceeding a preset threshold; The supporting triggering conditions in the condition judgment step include simultaneously satisfying the door extension length reaching or exceeding a preset threshold and the suspended door operation status signal indicating that the suspended door is in a closed operation state.

[0037] Furthermore, the process between the acquisition step and the conditional judgment step also includes: Phase identification step: The control processing component generates an operating phase signal based on the rate of change of the gate extension status signal and inputs the operating phase signal into the condition judgment step. The condition judgment step only performs the judgment on the support triggering condition when the operating phase signal indicates that the suspended gate is in a uniform speed operation phase or a deceleration operation phase. Between the conditional judgment step and the instruction expansion step, there is also: Early triggering step: When the gate extension status signal indicates that the gate extension length has entered the preset warning range, the control processing component sends the support wheel 24 deployment control command to the execution drive component in advance, so that the support wheel 24 can complete the deployment before the gate reaches the maximum extension position.

[0038] Furthermore, the status feedback step is as follows: the status detection unit of the support wheel 24 outputs the contact signal between the support wheel 24 and the ground and / or the extreme position signal of the support wheel 24 as the status signal of the support wheel 24; The steps following the deployment of the support wheel also include: The judgment step is completed: the control processing component determines whether the support wheel 24 has reached the fully deployed state based on the status signal of the support wheel 24.

[0039] Furthermore, the completion determination step also includes the following if the support wheel 24 fails to reach the fully deployed state within a preset time: Abnormal handling steps: The control processing component outputs an abnormal status signal and controls the suspended door to stop operating.

[0040] An anti-sagging control system for a suspended door includes: a support wheel mechanism 4; an operating status acquisition component; a control processing component; and an execution drive component. The support wheel mechanism 4 is set on the bottom beam 11 of the suspended door and includes a mounting base 41 and a ball screw structure 411. The ball screw structure 411 includes a screw motor 411a, a screw component 411b, a guide rail 411c and a ball component 411d. The crank rod 42 is hinged to the ball component 411d. The connecting rod 43 is fixed to the crank rod 42 and forms a fixed angle with the crank rod 42. The two ends of the pull rod 44 are respectively hinged to the mounting base 41 and the connecting rod 43. The support wheel 24 is installed at the end of the connecting rod 43 away from the crank rod 42 and is used to switch between the unfolded state and the retracted state to support the bottom of the door. The operation status acquisition component is installed on the cantilever gate and includes a gate body status detection unit, a gate displacement detection unit, and a support wheel 24 status detection unit, which are used to output the cantilever gate operation status signal, the gate extension status signal, and the support wheel 24 status signal. A control processing component is installed on the cantilever gate and electrically connected to the operation status acquisition component. It is used to receive the cantilever gate operation status signal, the gate extension status signal and the support wheel 24 status signal, and output the support wheel 24 deployment control command or the support wheel 24 retraction control command. The drive assembly is mounted on the bottom beam 11 of the gate and connected to the control processing assembly and the ball screw structure 411. It is used to drive the screw motor 411a to drive the support wheel 24 to unfold or retract according to the control command for unfolding or retracting the support wheel 24.

[0041] Furthermore, in the ball screw structure 411, the ball element 411d is movably mounted on the screw element 411b and guided by the guide rail 411c, so that it can move linearly along the guide rail 411c when the screw motor 411a drives the screw element 411b to rotate. The control processing component is configured to make a joint judgment based on the gate extension length corresponding to the gate extension status signal and the suspended door closing operation status corresponding to the suspended door operation status signal, in order to determine whether to output the support wheel 24 deployment control command. The control processing component is configured to generate an operating phase signal based on the rate of change of the gate extension status signal, and to allow the output of the support wheel 24 deployment control command when the operating phase signal indicates that the cantilever gate is in a constant speed operating phase or a deceleration operating phase.

[0042] Furthermore, the control processing component is configured to output a control command to deploy the support wheel 24 in advance when the gate extension status signal indicates that the gate extension length has entered a preset warning range; The support roller 24 status detection unit includes a ground contact detection component and an extreme position detection component, which are used to output the ground contact signal of the support roller 24 and the extreme position signal of the support roller 24, respectively.

[0043] Furthermore, the control processing component is configured to output an abnormal status signal and control the suspended gate to stop operating if it does not receive a ground contact signal or a limit position signal of the support wheel 24 from the support wheel 24 status detection unit within a preset time after the output support wheel 24 deployment control command is given. The control processing component is configured to prohibit the output of control commands to deploy the support wheels 24 when the suspended gate operation status signal indicates that the suspended gate is in the open operation state.

[0044] Furthermore, the drive assembly is configured to output a forward drive signal to the lead screw motor 411a to drive the support wheel 24 to unfold, output a reverse drive signal to the lead screw motor 411a to drive the support wheel 24 to retract, and output a stop drive signal to the lead screw motor 411a when it receives the limit position signal of the support wheel 24.

[0045] Reference Figures 7 to 9 This embodiment provides a method for controlling the sagging of a suspended door and a specific implementation of its support wheel mechanism 4. To facilitate the explanation of the structural relationship and movement process of the support wheel mechanism 4 under different operating states, key connection positions and movement positions are marked with several letter points in the figure.

[0046] like Figures 7 to 9 As shown, point O represents the extreme position of ball bearing 411d at one end of ball screw structure 411, corresponding to the position of ball bearing 411d when support wheel 24 is in the fully retracted state; point Q represents another preset position of ball bearing 411d in ball screw structure 411, corresponding to the position of ball bearing 411d when support wheel 24 is in the fully extended state; point P represents the real-time movement position of ball bearing 411d in ball screw structure 411. Ball bearing 411d reciprocates between point O and point Q to realize the extension or retraction of support wheel 24.

[0047] Point S represents the connection fulcrum of the pull rod 44 on the mounting base 41. Point S is the fixed connection reference point of the support wheel mechanism 4 relative to the bottom beam 11 of the door row. Point R represents the connection fulcrum between the crank rod 42 and the connecting rod 43. The crank rod 42 converts the linear motion of the ball bearing 411d into the oscillation of the connecting rod 43 through point R. Point T represents the connection fulcrum between the pull rod 44 and the connecting rod 43. The pull rod 44 constrains the motion trajectory of the connecting rod 43 through point T. Point U represents the mounting point of the support wheel 24. The support wheel 24 is mounted on the end of the connecting rod 43 away from the crank rod 42 and moves with the connecting rod 43 through point U.

[0048] With support wheel 24 in the deployed state, as Figure 7 As shown, the ball bearing 411d is located at point Q. One end of the crank 42 is connected to the ball bearing 411d. The crank 42 drives the connecting rod 43 to rotate via point R. The connecting rod 43 swings downward under the constraint of the tie rod 44 through points T and S, causing the support wheel 24 to move to the position in contact with the ground via point U, thereby providing support for the front end of the gate. At this time, the suspended gate is in the closed operation stage, and the gate extends a large length. The support wheel 24 participates in bearing the load to prevent the gate from sagging.

[0049] During the transition of support wheel 24 from the deployed state to the retracted state, such as Figure 8 As shown, the ball bearing 411d moves from point Q to point O. The linear displacement of the ball bearing 411d is gradually transmitted through the linkage of the crank 42, connecting rod 43 and pull rod 44. The support wheel 24 leaves the ground through point U and enters the recovery process, forming an intermediate transition state.

[0050] When the support wheel 24 is fully retracted, as Figure 9 As shown, the ball bearing 411d moves to position O, and the connecting rod 43 and the pull rod 44 rotate to the storage posture under the drive of the crank rod 42. The support wheel 24 completely leaves the ground through point U and is arranged close to the bottom beam 11 of the door. At this time, the suspended door is in the open operation stage. The support wheel 24 does not participate in the support and will not interfere with the operation of the suspended door.

[0051] In the above implementation process, the operation status acquisition component acquires the operation status signal of the suspended gate and the extension status signal of the gate panel. The control processing component determines whether the gate panel meets the support triggering condition based on the signals, and when the condition is met, controls the execution drive component to drive the ball screw structure 411, causing the ball component 411d to move between point O and point Q. This, in turn, drives the support wheel 24 to switch between the extended and retracted states through the real-time change of point P. Through the above point-position relationship and linkage mechanism, the support wheel 24 can participate in support as needed according to the operation status of the suspended gate, thereby improving the stress state during the operation of the suspended gate.

[0052] The core principle of this case is to actively control the deployment of the support rollers 24 when the gate is in a state of operation prone to sagging, so that the support rollers 24 contact the ground and provide temporary support to the front end of the gate. This changes the stress conditions of the gate in the cantilever state and reduces the bending moment and downward deflection caused by the gate's own weight. When the support is not required, the support rollers 24 are controlled to retract in time so that they do not participate in the operation of the gate, thereby avoiding interference and additional resistance.

[0053] In terms of specific mechanism, during the closing operation of the suspended gate, the gate panel gradually extends outward, increasing the distance between the front end of the gate panel and the support base. This increases the downward bending moment caused by the gate panel's own weight, which is the main reason for the gate panel sagging. This design uses an operating status acquisition component and a gate panel displacement detection unit to acquire the operating status signal and gate panel extension status signal of the suspended gate. The control processing component determines whether the gate panel has entered a high-risk sagging condition based on these signals. When the determination result indicates that the gate panel extension length reaches a preset threshold and the suspended gate is in the closing operation phase, the control processing component outputs a control command to deploy the support wheel 24, which in turn drives the ball screw structure 411 to operate via the execution drive component.

[0054] Under the control of the drive assembly, the ball screw structure 411 converts the rotational motion of the screw into the linear displacement of the ball bearings 411d. This linear displacement is transmitted and converted into force and displacement through a linkage mechanism consisting of the crank 42, connecting rod 43, and pull rod 44, causing the support roller 24 to move downward from its storage position along a predetermined trajectory and contact the ground. When the support roller 24 contacts the ground, the front end of the gate changes from a completely cantilevered state to a state where the load is shared by the suspended support and the ground support, thereby significantly reducing the downward bending tendency of the front end of the gate and suppressing sagging and slight tilting.

[0055] During and after the deployment of the support rollers 24, the support roller 24 status detection unit detects the status of the support rollers 24 and feeds back the detected status signal to the control processing component. This allows the control processing component to confirm whether the support rollers 24 have reached the expected support state, thus forming a closed-loop control mechanism that coordinates operation status acquisition, condition judgment, execution drive, and status feedback. When the suspended gate switches from the closed state to the open state, or when the gate extension length decreases to a range where support is no longer needed, the control processing component outputs a support roller 24 retraction control command, and the execution drive component reverses the drive of the ball screw structure 411, causing the support rollers 24 to be retracted and lifted off the ground through the linkage mechanism, thereby restoring the suspended gate to its normal operating state.

[0056] Based on the above principles and mechanisms, this invention enables the support rollers 24 to be deployed and retracted as needed during the operation of the suspended gate, allowing the support rollers 24 to participate in load bearing only under necessary working conditions. This avoids the problem of passively suppressing sagging by increasing the rigidity or weight of the gate structure, thereby improving the stability and reliability of the suspended gate during operation from the perspective of control and force conversion.

[0057] This case also illustrates another embodiment, such as Figure 1 and Figure 6 As shown, an anti-sagging type gate for a suspended gate is provided in this embodiment of the invention. The gate is provided with a bottom beam 11 located at the bottom of the gate, and the bottom beam 11 is provided with a support wheel mechanism 4. The support wheel mechanism 4 includes: Mounting base 41, with ball screw structure 411 arranged thereon; The crank 42 has one end connected to the ball component 411d of the ball screw structure 411; Link 43, one end of which is connected to the other end of crank 42 and forms a fixed angle with crank 42; Pull rod 44, one end of which is connected to mounting base 41, and the other end is connected to connecting rod 43; Support wheel 24 is installed at the end of connecting rod 43 away from crank rod 42.

[0058] In this design, the lead screw motor 411a drives the ball bearing 411d to reciprocate, causing the ball bearing 411d to move together with the crank rod 42 and the connecting rod 43. When the ball bearing 411d moves in the first direction M, the support roller 24 gradually opens to the optimal support point, allowing the support roller 24 to touch the ground and provide support, preventing the cantilever gate from sagging due to excessive extension. When the ball bearing 411d moves in the opposite direction N, the support roller 24 gradually retracts until it is fully retracted.

[0059] This structure is robust and reliable, with strong support and is not easily damaged, making it more suitable for the support strength of cantilever gates. The entire opening and closing process of the support wheels 24 can be achieved without the need for a costly gearbox structure, making the structure simpler and more robust.

[0060] Furthermore, the ball screw structure 411 includes a screw motor 411a, a screw component 411b, a guide rail 411c, and the ball component 411d movably mounted on the screw and the guide rail; One end of the crank 42 is hinged to the ball bearing 411d; One end of the connecting rod 43 is fixedly connected to the other end of the curved rod 42, and forms a fixed angle with the curved rod 42; One end of the pull rod 44 is hinged to the mounting base 41, and the other end is hinged to the connecting rod 43.

[0061] Furthermore, it also includes: Doorway top beam 16, located at the top of the doorway; The bottom beam rack 33 is installed inside the bottom beam 11 of the portal frame; The door tail diagonal tie rod 34 is connected at both ends to the top beam 16 and the bottom beam 11 of the door row, respectively.

[0062] An anti-sagging suspended door includes: The main gantry frame 31 has a first embedded part 311 at its bottom; The secondary gantry 32 is arranged on one side of the main gantry 31, and a second embedded part 321 is embedded at the bottom. The main drive motor 35 is mounted on the main gantry 31 and includes an output shaft that meshes with the bottom beam rack 33; The main pulley assembly 36 is located inside the bottom beam 11 of the portal frame and on the main gantry frame 31; The secondary pulley assembly 37 is located within the bottom beam 11 of the portal frame and on the side of the main gantry frame 31 away from the secondary gantry frame 32, with a third embedded part 371 embedded at its bottom; and The gate panel is an anti-sagging type gate panel of any of the aforementioned suspended gates.

[0063] This solution addresses the problem that existing suspended door panels, when extended to a large length, are prone to sagging and uneven stress due to their own weight, and are difficult to effectively suppress through passive structures. The solution involves installing a support wheel mechanism 4 on the bottom beam 11 of the door panel, consisting of a mounting base 41, a ball screw structure 411, a crank 42, a connecting rod 43, a tie rod 44, and a support wheel 24, which provides active support to the bottom of the door panel through a controllable mechanical transmission method.

[0064] Specifically, the ball screw structure 411, driven by the screw motor 411a, drives the ball component 411d to reciprocate along a preset direction. The linear displacement of the ball component 411d is transmitted to the connecting rod 43 through the crank 42 connected to it, and under the constraint of the fixed angle between the crank 42 and the connecting rod 43, it is converted into the swing motion of the connecting rod 43. Since the other end of the connecting rod 43 is equipped with a support wheel 24, and forms a geometric constraint relationship with the mounting base 41 through the tie rod 44, the connecting rod 43 can drive the support wheel 24 to switch between the storage position and the support position during the swing, thereby realizing the downward movement or upward movement of the support wheel 24 relative to the bottom beam 11 of the door.

[0065] As the gate opens and its extension length increases, the ball bearing 411d moves in the corresponding direction, causing the support roller 24 to gradually unfold and contact the ground, forming an additional support point at the bottom of the gate. This shares the downward bending load caused by the cantilevered state of the gate, reduces the deflection change at the front end of the gate, and lowers the probability of gate sagging. Compared to methods that rely solely on the rigidity of the gate itself or fixed reinforcing structures, this support method can actively participate in the stress distribution according to the gate's operating state, effectively improving the overall stress condition of the gate under different extension conditions.

[0066] When the gate is retracted or in a state where no auxiliary support is needed, the ball bearing 411d is controlled to move in the opposite direction, so that the support wheel 24 is gradually retracted into the bottom beam 11 of the gate under the transmission action of the crank 42 and the connecting rod 43. This avoids the support wheel 24 from being in long-term contact with the ground and generating additional resistance or wear, thus balancing the smooth operation of the gate and the durability of the structure.

[0067] Furthermore, this solution achieves the unfolding and retraction of the support wheel 24 through the mechanical transmission relationship formed by the ball screw structure 411, the crank 42, and the connecting rod 43. It eliminates the need for complex gearboxes or multi-stage transmission mechanisms, and the structure is clearly defined with a clear transmission path, which helps improve the stability and reliability of the overall mechanism and is suitable for long-term use in suspended door panels.

[0068] In other embodiments, such as Figures 1-5 As shown, this embodiment provides a gate structure for a suspended door, including: The bottom beam 11 of the gate is located at the bottom of the gate and extends along the length of the gate, serving as the basic load-bearing component of the gate; The gate railing 12 is installed above the gate bottom beam 11 and connected to the gate bottom beam 11, and is arranged along the length of the gate to form the upper external structure of the gate. The gate diagonal brace 13 is set above the gate bottom beam 11 and below the gate railing 12, is set along the length of the gate, and is fixed in the gate structure in a cross manner to enhance the overall structural strength of the gate. A diagonal brace baffle 14 is provided on the outside of the diagonal brace 13 of the gate, extends along the length of the gate, and is connected to the bottom beam 11 of the gate and the gate railing 12. It is used to cover the diagonal brace 13 of the gate, so that the diagonal brace 13 of the gate is hidden inside the gate when the gate is in normal use.

[0069] This design conceals the doorway's diagonal bracing 13 within the doorway structure during normal use by placing it above the bottom beam 11 and below the doorway railing 12, with a bracing baffle 14 on its outer side. This prevents the bracing 13 from being directly exposed as a structural component. The diagonal bracing 13 remains fixed to the doorway structure in a crisscross pattern, continuing its structural reinforcement function. Simultaneously, the baffle 14 conceals it, resulting in a continuous and simple external appearance, significantly improving the overall visual effect of the doorway. The doorway railing 12 and diagonal bracing 13 are arranged in layers along their height, preventing overlap at the same visual level and creating a clear hierarchy and more coherent lines in the external structure. The concealment of the diagonal bracing 13 within the doorway reduces the risk of accidental contact and bumping, while the baffle 14 provides some protection to the internal structure and facilitates later cleaning and maintenance.

[0070] In summary, by improving the structural arrangement of the door panel tie rod 13, this case achieves a synergistic improvement in appearance simplicity, safety, and structural stability while ensuring the structural strength of the suspended door panel.

[0071] Furthermore, it also includes a door panel top beam 16, which is disposed on the upper part of the door panel; The gate railing 12 is set in the upper area of ​​the gate, and its height accounts for 30%-60% of the total height of the gate. The gate diagonal brace 13 is set in the lower area of ​​the gate, and its height accounts for 40%-70% of the total height of the gate, so that the gate forms a layered layout of upper appearance functional area and lower structural reinforcement area in the height direction. The central axis 131 of the door panel diagonal brace 13 is located within the range of 1 / 4 to 1 / 2 of the total height of the door panel from the upper surface of the door panel bottom beam 11, so that the door panel diagonal brace 13 is arranged in the area where the bending moment of the door panel is large, thereby improving the door panel's anti-sagging ability.

[0072] Furthermore, the adjacent door row diagonal braces 13 are arranged in a cross manner, with a cross angle of 30° to 60°, so as to form a stable force triangle structure within the limited door row space; The upper end of the diagonal brace baffle 14 is connected to the transverse member 15 in the middle of the gate, and the lower end of the diagonal brace baffle 14 is connected to the bottom beam 11 of the gate, so that the diagonal brace baffle 14 is correspondingly set with the gate diagonal brace 13 in the height direction of the gate, thereby improving the overall structural rigidity of the gate together with the gate diagonal brace 13.

[0073] Furthermore, the distance between the outer surface of the inclined tie rod baffle 14 and the outer surface of the gate railing 12 is no more than 10mm, so that the outer side of the gate forms a continuous facade structure; The diagonal brace baffle 14 is installed on the gate structure by means of bolt connection, snap connection or sliding groove insertion, so as to facilitate the installation, maintenance or replacement of the gate diagonal brace 13.

[0074] Furthermore, a support wheel assembly 2 is provided inside the front end of the bottom beam 11 of the gate, and the support wheel assembly 2 is connected to the bottom beam 11 of the gate to provide ground support for the front end of the gate when the gate moves to the predetermined position; like Figure 4 As shown, the support wheel assembly 2 includes a drive wheel motor 21, a bevel gearbox 22, a wheel frame 23, and a support wheel 24. The drive wheel motor 21 is connected to the bevel gearbox 22, the wheel frame 23 is mounted on the output shaft of the bevel gearbox 22, and the support wheel 24 is mounted on the end of the wheel frame 23 away from the bevel gearbox 22, so that the drive wheel motor 21 drives the wheel frame 23 to swing through the bevel gearbox 22, thereby driving the support wheel 24 to retract and extend. Specifically, when the length of the cantilever gate is large, the front end of the gate tends to sag due to its own weight when it is in a cantilevered state when it is open or close to the end of the closing position. In this case, by setting the support wheel assembly 2 inside the front end of the gate bottom beam 11, a controllable ground support point can be formed at the front end of the gate when it runs to the predetermined position. Unlike methods using fixed, exposed support wheels, this design utilizes a drive wheel motor 21 in conjunction with a bevel gearbox 22 to drive the wheel frame 23 to swing around its axis. This allows the support wheel 24 to extend or retract within the bottom beam 11 of the gate, ensuring that the support wheel only participates in bearing load when support is needed and completely retracts when no support is required. Furthermore, the retractable support wheel structure provides support only to the front end of the gate during critical stroke sections where the gate is subjected to unfavorable loads, effectively suppressing gate sagging. It avoids structural redundancy and aesthetic damage caused by long-term load-bearing or fixed, exposed support wheels. The support function matches the gate's operating state, resulting in a more rational overall structure.

[0075] Furthermore, the motor shaft of the drive wheel motor 21 is arranged along the length direction of the gate bottom beam 11, and the bevel gearbox 22 is used to change the power transmission direction so that the swing axis of the wheel frame 23 is adapted to the internal space structure of the gate bottom beam 11. When the support wheel assembly 2 is fully retracted, its drive wheel motor 21, bevel gearbox 22, wheel frame 23, and support wheel 24 are all located within the outer contour of the gate bottom beam 11, ensuring that the gate bottom beam 11 maintains a continuous, flat appearance with no exposed parts. Given the limited internal space of the gate bottom beam 11, if the drive wheel motor 21 is arranged perpendicular to the length of the bottom beam, it can easily cause local structural protrusions in the bottom beam, affecting the overall appearance and structural continuity of the gate. This design addresses this by arranging the motor shaft of the drive wheel motor 21 along the length of the gate bottom beam 11 and using the bevel gearbox 22 to change the power transmission direction, thus adapting the swing axis of the wheel frame 23 to the internal spatial structure of the gate bottom beam 11, thereby achieving a forward arrangement of the drive mechanism along the length of the bottom beam. In this structure, the drive wheel motor 21, bevel gearbox 22, wheel frame 23, and support wheel 24 can be entirely accommodated within the internal contour of the gate bottom beam 11. Furthermore, it significantly improves the compactness of the support wheel assembly 2 inside the door bottom beam 11; avoids the bottom beam protruding or additional outer cover structure caused by unreasonable drive mechanism direction; when the support wheel 24 is fully retracted, the lower surface of the door bottom beam 11 remains continuous and flat, which is conducive to maintaining the consistency and integrity of the overall appearance of the suspended door; and achieves true hidden support wheels through the optimization of the structural layout, rather than simple obstruction.

[0076] Furthermore, a support wheel assembly 2 is provided inside the front end of the bottom beam 11 of the gate, and the support wheel assembly 2 is connected to the bottom beam 11 of the gate to provide ground support for the front end of the gate when the gate moves to the predetermined position; like Figure 5 As shown, the support wheel assembly 2 includes: The drive wheel motor 21 is connected to the first bevel gear 25; The wheel frame 23 has a second bevel gear 26 at one end that meshes with the first bevel gear 25; Support wheel 24 is installed at the end of wheel frame 23 away from the second bevel gear 26. The motor shaft of the drive wheel motor 21 is arranged along the length of the gate bottom beam 11. The first bevel gear 25 and the second bevel gear 26 are used to change the direction of power transmission, so that the swing axis of the wheel frame 23 is adapted to the internal spatial structure of the gate bottom beam 11. When the support wheel assembly 2 is fully retracted, its drive wheel motor 21, first bevel gear 25, second bevel gear 26, wheel frame 23, and support wheel 24 are all located within the outer contour of the gate bottom beam 11, so that the appearance of the gate bottom beam 11 remains continuous, flat, and without exposed parts. Specifically, during the operation of the suspended gate, the stress state experienced by the gate at different positions is not the same. When the gate is fully open or in the middle operating position, the cantilever length at the front end of the gate is relatively short, and the overall rigidity of the gate meets the usage requirements. However, when the gate moves to a position close to the closing end, the cantilever length at the front end reaches its maximum, and the bending moment borne by the gate's bottom beam 11 and the gate structure also increases accordingly. The current structure limits the support wheel assembly 2 to participate in support when the gate moves to a predetermined position, so that the support wheel provides ground support during the most unfavorable stage of the gate's stress, thereby forming effective support for the front end of the gate. Furthermore, the support wheel only works in the necessary stroke section, avoiding ineffective support; it improves the stability of the long gate during operation without increasing the overall weight and structural complexity of the gate; and it matches the gate's support structure with the stress state of the gate, making the overall design more in line with actual working conditions.

[0077] A novel suspended door, comprising the gate structure for a suspended door as described in any of the preceding claims.

[0078] Furthermore, it also includes: The main gantry frame 31 has a first embedded part 311 at its bottom; The secondary gantry 32 is arranged on one side of the main gantry 31, and a second embedded part 321 is embedded at the bottom. The bottom beam rack 33 is installed inside the bottom beam 11 of the portal frame; The door tail diagonal tie rod 34 is connected at both ends to the top beam 16 and the bottom beam 11 of the door row, respectively; The main drive motor 35 is mounted on the main gantry 31 and includes an output shaft that meshes with the bottom beam rack 33; The main pulley assembly 36 is located inside the bottom beam 11 of the portal frame and on the main gantry frame 31; The secondary pulley assembly 37 is located inside the bottom beam 11 of the gate and on the side of the main gantry 31 away from the secondary gantry 32, with a third embedded part 371 embedded at the bottom.

[0079] A new type of suspended door includes: Main gantry 31; Secondary gantry 32 is arranged on one side of main gantry 31; The gate is located on one side of the main gantry frame 31 and is configured to cooperate with the main gantry frame 31, and moves laterally along the opening and closing direction of the suspended door; The bottom beam 11 of the gate is provided at the lower part of the gate and extends along the length of the gate; The gate railing 12 is installed above the gate bottom beam 11 and connected to the gate bottom beam 11, and is arranged along the length of the gate to form the upper external structure of the gate. The gate diagonal brace 13 is set above the gate bottom beam 11 and below the gate railing 12, is set along the length of the gate, and is fixed in the gate structure in a cross manner to enhance the overall structural strength of the gate. A diagonal brace baffle 14 is provided on the outside of the diagonal brace 13 of the gate, extends along the length of the gate, and is connected to the bottom beam 11 of the gate and the gate railing 12. It is used to shield the diagonal brace 13 of the gate, so that the diagonal brace 13 of the gate is hidden inside the gate when the suspended gate is in normal use.

[0080] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art should be included within the protection scope of the present invention.

Claims

1. A method for controlling the sagging of a suspended door, characterized in that, Includes the following steps: Operation acquisition steps: The operation status acquisition component acquires the floating door operation status signal and the door extension status signal and sends them to the control processing component; Condition judgment step: The control processing component determines the support triggering condition based on the suspended door operation status signal and the door extension status signal and outputs the trigger judgment signal; Unfolding instruction steps: When the trigger judgment signal is true, the control processing component sends the support wheel (24) unfolding control instruction to the execution drive component; The support wheel deployment step: The drive assembly drives the ball screw motor (411a) of the ball screw structure (411) to move the ball component (411d) of the ball screw structure (411) and through the linkage of the crank (42), connecting rod (43) and pull rod (44), the support wheel (24) contacts the ground. Status feedback steps: The support wheel (24) status detection unit acquires the status signal of the support wheel (24) and feeds it back to the control processing component; Storage instruction steps: When the trigger judgment signal is false or the floating door operation status signal indicates that the floating door is in the open operation state, the control processing component sends the support wheel (24) storage control instruction to the execution drive component; Support wheel storage steps: The drive assembly reverses the movement of the ball bearing (411d) of the ball screw structure (411) to move the support wheel (24) off the ground.

2. The anti-sagging control method for a suspended door according to claim 1, characterized in that, The operation acquisition steps are as follows: the door status detection unit outputs the suspended door opening status signal or the suspended door closing status signal as the suspended door operation status signal, and the door displacement detection unit outputs the door extension length signal as the door extension status signal. The support triggering conditions in the condition judgment step include the gate extension length reaching or exceeding a preset threshold; The supporting triggering conditions in the condition judgment step include simultaneously satisfying the door extension length reaching or exceeding a preset threshold and the suspended door operation status signal indicating that the suspended door is in a closed operation state.

3. The anti-sagging control method for a suspended door according to claim 2, characterized in that, Between the acquisition step and the conditional judgment step, there is also: Phase identification step: The control processing component generates an operating phase signal based on the rate of change of the gate extension status signal and inputs the operating phase signal into the condition judgment step. The condition judgment step only performs the judgment on the support triggering condition when the operating phase signal indicates that the suspended gate is in a uniform speed operation phase or a deceleration operation phase. Between the conditional judgment step and the instruction expansion step, there is also: Early triggering step: When the gate extension status signal indicates that the gate extension length has entered the preset warning range, the control processing component sends the support wheel (24) deployment control command to the execution drive component in advance so that the support wheel (24) can be deployed before the gate reaches the maximum extension position.

4. The anti-sagging control method for a suspended door according to claim 3, characterized in that, The status feedback steps are as follows: the support wheel (24) status detection unit outputs the support wheel (24) contact signal with the ground and / or the support wheel (24) limit position signal as the support wheel (24) status signal; The steps following the deployment of the support wheel also include: Complete the judgment step: The control processing component determines whether the support wheel (24) has reached the unfolded state based on the status signal of the support wheel (24).

5. The anti-sagging control method for a suspended door according to claim 4, characterized in that, The completion judgment step also includes the following if the support wheel (24) fails to reach the fully deployed state within a preset time: Abnormal handling steps: The control processing component outputs an abnormal status signal and controls the suspended door to stop operating.

6. A sag control system for a suspended door, characterized in that, include: The support wheel mechanism (4) is set on the bottom beam (11) of the gate of the suspended door, including the mounting base (41) and the ball screw structure (411). The ball screw structure (411) includes the screw motor (411a), the screw component (411b), the guide rail (411c) and the ball component (411d). The crank rod (42) is hinged to the ball component (411d). The connecting rod (43) is fixed to the crank rod (42) and forms a fixed angle with the crank rod (42). The two ends of the pull rod (44) are respectively hinged to the mounting base (41) and the connecting rod (43). The support wheel (24) is installed at the end of the connecting rod (43) away from the crank rod (42) and is used to switch between the unfolded state and the retracted state to support the bottom of the gate. The running status acquisition component is set on the suspended gate, including a gate body status detection unit, a gate displacement detection unit and a support wheel (24) status detection unit, which are used to output the suspended gate running status signal, the gate extension status signal and the support wheel (24) status signal; The control processing component is installed on the suspended gate and electrically connected to the running status acquisition component. It is used to receive the running status signal of the suspended gate, the gate extension status signal and the support wheel (24) status signal and output the support wheel (24) unfolding control command or the support wheel (24) retracting control command. The drive assembly is mounted on the bottom beam (11) of the gate and connected to the control processing assembly and the ball screw structure (411). It is used to drive the screw motor (411a) to drive the support wheel (24) to unfold or retract according to the control command for unfolding or retracting the support wheel (24).

7. The anti-sagging control system for a suspended door according to claim 6, characterized in that, In the ball screw structure (411), the ball component (411d) is movably mounted on the screw component (411b) and guided by the guide rail (411c) so that it can move linearly along the guide rail (411c) when the screw motor (411a) drives the screw component (411b) to rotate. The control processing component is configured to make a joint judgment based on the gate extension length corresponding to the gate extension status signal and the suspension door closing operation status corresponding to the suspension door operation status signal, so as to determine whether to output the support wheel (24) deployment control command. The control processing component is configured to generate an operating phase signal based on the rate of change of the gate extension status signal, and to allow the output of a support wheel (24) deployment control command when the operating phase signal indicates that the suspended gate is in a constant speed operating phase or a deceleration operating phase.

8. The anti-sagging control system for a suspended door according to claim 7, characterized in that, The control processing component is configured to output a control command to deploy the support wheel (24) in advance when the gate extension status signal indicates that the gate extension length has entered a preset warning range; The support roller (24) status detection unit includes a ground contact detection component and an extreme position detection component, which are used to output the support roller (24) contact signal with the ground and the support roller (24) extreme position signal, respectively.

9. The anti-sagging control system for a suspended door according to claim 8, characterized in that, The control processing component is configured to output an abnormal status signal and control the suspended door to stop operating if it does not receive the contact signal between the support wheel (24) and the ground or the limit position signal of the support wheel (24) from the support wheel (24) status detection unit within a preset time after the output support wheel (24) unfold control command is given; The control processing component is configured to prohibit the output of support wheel (24) deployment control commands when the suspended gate operation status signal indicates that the suspended gate is in the open operation state.

10. The anti-sagging control system for a suspended door according to claim 9, characterized in that, The drive assembly is configured to output a forward drive signal to the lead screw motor (411a) to drive the support wheel (24) to unfold, output a reverse drive signal to the lead screw motor (411a) to drive the support wheel (24) to retract, and output a stop drive signal to the lead screw motor (411a) when the limit position signal of the support wheel (24) is received.

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