Linear drive with contact safety nut and aerial work platform

Abstract

The application relates to the technical field of aerial work platforms, in particular to a linear driver with a contact type safety nut and an aerial work platform. The linear driver comprises a central screw rod, a transmission nut mechanism and a safety nut mechanism. The central screw rod has a spiral raceway. The safety nut mechanism comprises a safety nut seat sleeved on the periphery of the central screw rod. A limiting hole channel is formed in the safety nut seat and points to the central screw rod. An elastic buffer is arranged in the limiting hole channel. A safety ball is arranged between the elastic buffer and the central screw rod. The safety ball is partially located in the spiral raceway and partially located in the limiting hole channel. The safety ball can roll along the spiral raceway and can move along the limiting hole channel. The contact type safety nut can keep the linear driver safe, stable and accurate during the conversion process when the transmission nut mechanism fails and the safety nut mechanism works.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aerial work platforms, and particularly relates to a linear driver with a contact type safety nut and an aerial work platform. BACKGROUND

[0002] Linear actuators are widely used in various fields, including medical devices, home and office, solar power generation, etc. The structure of the linear actuator usually includes a driving motor, a transmission screw, a worm gear and a transmission nut. The driving motor drives the rotating screw to rotate, and the rotating screw drives the transmission nut to move axially when the rotating screw rotates. The transmission nut can be connected to a driven object to achieve the driving purpose. When running, the linear actuator not only needs to bear the axial force, but also needs to bear a certain lateral force, so that the transmission nut is damaged due to abnormal wear and material defects, thereby causing sudden drop and high risk. In order to improve the safety performance during use, a safety nut is arranged in the transmission nut of many linear actuators. The safety nut is not arranged on the thread or ball of the transmission nut to keep the push rod continue to run after the thread or ball is damaged, but only allows the push rod to drop to a safe position. When the transmission nut is running normally, the safety nut is not in action, so the safety nut is usually not engaged with the screw at this time. When the transmission nut is damaged during the ascending process, the linear actuator will not continue to ascend, but will rotate at the original position. If the motor is reversed, the linear actuator can be returned to the safe position by the transmission of the safety nut.

[0003] Because the safety nut is engaged with the screw rod to play a role only when the screw rod fails, the safety nut is not in action when the screw rod lifter is running normally, and the safety nut is not engaged with the screw rod, which does not affect the normal operation of the screw rod lifter. For example, a lifting device disclosed in a patent with publication number CN113840794A includes a center screw rod, a main nut mechanism, and an auxiliary nut mechanism. The main nut mechanism is engaged with the center screw rod, and the auxiliary nut mechanism is disengaged from the center screw rod. In the event of a failure of the main nut mechanism, the auxiliary nut mechanism is configured to engage the center screw rod to avoid the dangerous situation of the lifting device descending rapidly. Then, the lifting controller is configured to allow the work platform to descend to a stowed or transport position to allow the worker or operator to safely leave the carrier. The auxiliary nut mechanism in the patent can engage the center screw rod in the event of a failure of the main nut mechanism to play a role in ensuring safety, but the auxiliary nut mechanism is always disengaged from the center screw rod when the main nut mechanism is running normally. Therefore, a relatively severe impact will occur when the auxiliary nut mechanism engages the center screw rod, which may cause damage to the center screw rod and the auxiliary nut mechanism, and cause relatively severe vibration of the actuator and the lifted platform, which endangers the safety of the personnel on the platform. In addition, after the auxiliary nut mechanism acts, the lifting device is not directly stationary at the current position waiting for maintenance, and the actuator still needs to operate to complete the current lifting task or at least needs to descend to a safe height. The auxiliary nut mechanism and the center screw rod are engaged through a helical thread, specifically by moving closer to each other along the axial direction of the center screw rod and engaging each other. Although the original gap is small, the engagement still causes a significant positional error of the actuator in the axial direction of the center screw rod, resulting in a large error in the entire lifting control. SUMMARY

[0004] The present application is improved in view of the above-mentioned prior art, i.e. the technical problem to be solved by the present application is to provide a linear drive with a contact safety nut, comprising a central screw rod, a transmission nut mechanism and a safety nut mechanism, the central screw rod has a spiral raceway, the safety nut mechanism comprises a safety nut seat sleeved on the periphery of the central screw rod, the safety nut seat is provided with a limiting hole channel pointing to the central screw rod, an elastic buffer is arranged in the limiting hole channel, a safety ball is arranged between the elastic buffer and the central screw rod, the safety ball is partially located in the spiral raceway and partially located in the limiting hole channel, and the safety ball can roll along the spiral raceway and can move along the limiting hole channel. The elastic buffer and the safety ball of the present application form an elastic ball mechanism, and the safety nut mechanism always maintains engagement with the central screw rod through the elastic ball mechanism. The transmission nut mechanism is, for example, a traditional ball screw nut, which converts the rotary actuation of the central screw rod into translational motion. In the normal working state of the transmission nut mechanism without failure, compared with the prior art in which the safety nut mechanism is disengaged from the central screw rod at this time, the safety nut mechanism of the present application always maintains elastic engagement with the central screw rod through the specially configured elastic ball mechanism, i.e. the contact safety nut. When the transmission nut mechanism fails, the elastic ball mechanism does not affect the engagement of the safety nut mechanism with the central screw rod.

[0005] As a preferred embodiment of the present application, a plurality of limiting hole channels are circumferentially arranged on the safety nut seat, and the elastic buffer and the safety ball are arranged in each limiting hole channel.

[0006] As a preferred embodiment of the present application, the inner wall of the safety nut seat has a spiral top tooth which extends into the spiral raceway and is spaced apart from the central screw rod.

[0007] As a preferred embodiment of the present application, the limiting hole channel is filled with oil, and the cross-sectional diameter of the limiting hole channel is consistent with the diameter of the safety ball.

[0008] As a preferred embodiment of the present application, the limiting hole channel penetrates the inner and outer walls of the safety nut seat, the safety ball seals the outlet of the limiting hole channel close to the central screw rod, a plunger is detachably mounted at the inlet of the limiting hole channel away from the central screw rod, the plunger seals the inlet of the limiting hole channel, and the elastic buffer is located between the plunger and the safety ball.

[0009] As a preferred embodiment of the present application, the safety nut seat and the transmission nut mechanism have a gap and form an oil supplement cavity, the oil supplement cavity surrounds the central screw rod, and the safety nut seat is provided with a transfer hole channel communicating the limiting hole channel and the oil supplement cavity.

[0010] As a preferred embodiment of the present application, the limiting hole channels are arranged in a circumferential array on the screw top teeth along the circumference of the safety nut seat.

[0011] As a preferred embodiment of the present application, the outlets of all the limiting hole channels are arranged along the helical extension direction of the screw top teeth.

[0012] As a preferred embodiment of the present application, the elastic buffer is a spring, and the diameter of the spring is smaller than the diameter of the safety ball.

[0013] A high-altitude operation platform comprising the linear driver with the contact safety nut.

[0014] Advantages:

[0015] The design of the contact safety nut enables the linear driver to maintain safety, stability and precision during the transition process when the transmission nut mechanism fails and the safety nut mechanism intervenes. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A perspective view of the transmission nut mechanism and the safety nut mechanism installed on the central screw rod;

[0017] Figure 2 A schematic view of the safety nut seat and the central screw rod;

[0018] Figure 3 A sectional view of Figure 1 ;

[0019] Figure 4 A schematic view of Figure 3 , in which the plunger and the elastic buffer are omitted;

[0020] Figure 5 A schematic view of the limiting hole channels with their outlets on the screw top teeth;

[0021] Figure 6 A schematic view of the outlets of all the limiting hole channels arranged along the helical extension direction of the screw top teeth on the screw top teeth;

[0022] Figure 7 A schematic view of the overall structure of the scissor lifting device;

[0023] Figure 8 A schematic view of the hydraulic buffer in operation;

[0024] Figure 9 A schematic view of the structure of the hydraulic buffer;

[0025] Figure 10 A schematic view of the lower connecting end;

[0026] Figure 11 This is a schematic diagram of the upper connection end;

[0027] In the diagram: 1. Central screw; 11. Spiral raceway; 2. Transmission nut mechanism; 3. Safety nut mechanism; 31. Safety nut seat; 32. Limiting channel; 33. Elastic buffer; 34. Safety ball; 35. Spiral tooth; 36. Piston; 37. Transfer channel; 38. Oil replenishment chamber; 4. Scissor mechanism; 41. Cross support; 42. Scissor frame; 5. Hydraulic buffer; 51. Hydraulic cylinder; 52. Piston rod; 53. Dust cover; 6. Lower connecting end; 61. Lower arc-shaped seat; 62. Lower arc groove; 63. Lower opening and closing part; 64. Mounting plate; 7. Upper connecting end; 71. Upper arc-shaped seat; 72. Upper arc groove; 73. Upper opening and closing part; 81. Lower fastener; 82. Upper fastener; 9. Lifting mechanism. Detailed Implementation

[0028] The following specific embodiments are merely illustrative of the present invention and are not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.

[0029] Example 1:

[0030] The linear driver with the contact type safety nut comprises a center screw rod 1, a transmission nut mechanism 2 and a safety nut mechanism 3, the center screw rod 1 has a spiral raceway 11, the safety nut mechanism 3 comprises a safety nut seat 31 sleeved on the periphery of the center screw rod 1, the safety nut seat 31 is not in contact with the center screw rod 1, the safety nut seat 31 is provided with a limiting hole channel 32 directed to the center screw rod 1, the limiting hole channel 32 is provided with an elastic buffer 33, the elastic buffer 33 is provided with a safety ball 34 between the center screw rod 1, the end of the elastic buffer 33 away from the safety ball 34 can be supported, specifically, the end of the elastic buffer 33 away from the safety ball 34 can be fixedly connected with the inner wall of the limiting hole channel 32, or the end of the limiting hole channel 32 away from the center screw rod 1 is not through but has a bottom surface, and the elastic buffer 33 directly abuts against the bottom surface, the safety ball 34 is partially located in the spiral raceway 11 and partially located in the limiting hole channel 32, the safety ball 34 can roll along the spiral raceway 11 and can move along the limiting hole channel 32, the safety ball 34 is completely attached to the spiral raceway 11, and the safety ball 34 can stably roll in the spiral raceway 11. When the linear driver normally operates, the transmission nut mechanism 2 mainly plays a transmission role, the safety nut mechanism 3 does not play a role but still needs to follow the transmission nut to move, only the safety ball 34 in the safety nut mechanism 3 falls in the spiral raceway 11 of the center screw rod 1 and can roll along the spiral raceway 11, the remaining components in the safety nut mechanism 3 are not in contact with the center screw rod 1, but the safety nut mechanism 3 is engaged with the center screw rod 1 through the safety ball 34, the safety ball 34 is located between the elastic buffer 33 and the center screw rod 1, and when the safety ball 34 is subjected to an external force, the safety ball 34 can move in the limiting hole channel 32 by overcoming the elastic force of the elastic buffer 33, so that the safety ball 34 is not tightly pressed in the spiral raceway 11, but only rolls along the spiral raceway 11, so that the existence of the safety ball 34 does not affect the normal operation of the transmission nut mechanism 2.When the transmission nut mechanism 2 fails, usually due to the loss of balls in the transmission nut mechanism 2; at this time in the axial direction along the center screw 1, the safety ball 34 in the safety nut mechanism 3 is tightly pressed against the side wall of the spiral raceway 11, and the safety ball 34 itself is completely in contact with the spiral raceway 11, so there is no displacement of the safety ball 34 in the axial direction, and there is no instantaneous violent impact between the safety ball 34 and the center screw 1 at the moment of action, ensuring the stability of the entire linear drive, and avoiding damage to the safety ball 34 and the center screw 1; and the safety ball 34 is partially located in the limiting hole 32, so it can limit the displacement of the safety nut seat 31 in the axial direction by blocking the limiting hole 32, so that the safety nut mechanism 3 will not cause position error in the axial direction of the linear drive when it is working, and the safety ball 34 also plays the role of replacing the lost balls in the transmission nut mechanism 2 at this time, temporarily playing a transmission role, so that the linear drive can still complete the current lifting task, or descend to a safe height. In short, it can still ensure the accuracy of operation, and there is no need to recheck the accuracy when replacing the transmission nut mechanism 2 later. In the lateral direction perpendicular to the axial direction of the center screw 1, the safety nut seat 31 is pressed towards the center screw 1, and the safety ball 34 will move towards the limiting hole 32 against the elastic force of the elastic buffer 33. The elastic buffer 33 plays a buffering role to avoid the safety nut mechanism 3 from shaking violently, avoid the linear drive from shaking violently, and ensure the safety of the lifting equipment, but in this direction the safety ball 34 cannot be tightly pressed in the spiral raceway 11, and the safety nut seat 31 is directly pressed on the center screw 1, playing the role of locking the center screw 1 by the safety nut mechanism 3, ensuring safety. In short, the design of the contact type safety nut makes the linear drive always maintain safety, stability and precision without loss during the conversion process when the transmission nut mechanism 2 fails and the safety nut mechanism 3 intervenes.

[0031] The limiting hole 32 in the embodiment refers to the center screw 1, and the extending direction of the limiting hole 32 is perpendicular to the axial direction of the center screw 1. There is only one safety ball 34 in each limiting hole 32 in the safety nut mechanism 3. In order to ensure the overall effect of the safety nut, the safety nut seat 31 is preferably provided with a plurality of limiting holes 32 in the circumferential direction, and each limiting hole 32 is provided with the elastic buffer 33 and the safety ball 34. In the embodiment, the safety nut mechanism 3 mainly relies on the direct extrusion of the safety nut seat 31 and the center screw 1 to resist the lateral force and play a locking role. However, the inner wall of the safety nut seat 31 and the center screw 1 are smoothly attached, and if the lateral force is small, the locking effect is general, and the locking effect in the axial direction is very general. Therefore, the inner wall of the safety nut seat 31 is preferably provided with a spiral tooth 35, which extends into the spiral raceway 11 and is spaced apart from the center screw 1. When the transmission nut mechanism 2 is normally running, the spiral tooth 35 does not contact the center screw 1. When the transmission nut mechanism 2 fails, the safety ball 34 still plays the above role, and the safety nut seat 31 no longer directly extrudes the center screw 1, but extrudes in the spiral raceway 11 of the center screw 1 through the spiral tooth 35. In this way, the spiral tooth 35 can directly press the center screw 1 in the lateral direction, and the locking effect is good. At the same time, it can also share the burden of the safety ball 34 in the axial direction, so as to ensure the strength and reliability of the safety nut mechanism 3.

[0032] When the transmission nut mechanism 2 is normally running, the safety ball 34 is not tightly pressed in the spiral raceway 11, and is rolling in the spiral raceway 11, so it will not have a great impact on the normal operation of the transmission nut mechanism 2. However, the friction between the safety ball 34 and the spiral raceway 11 will still have some impact on the normal operation of the transmission nut mechanism 2, especially the running efficiency, accuracy and energy consumption. Therefore, the limiting hole 32 is preferably filled with oil, and the cross-sectional diameter of the limiting hole 32 is consistent with the diameter of the safety ball 34. The outer circle of the safety ball 34 is completely attached to the inner wall of the limiting hole 32, and the safety ball 34 is clamped in the limiting hole 32 to limit the effect of the safety nut seat 31. The movement of the safety ball 34 in the limiting hole 32 is fully limited by the limiting hole 32, which is very stable. The safety ball 34 blocks the limiting hole 32 to prevent oil from flowing out of the limiting hole 32. The oil directly contacts the surface of the safety ball 34, and the safety ball 34 with oil on the surface rolls in the spiral raceway 11. The oil plays a lubricating role, reducing the friction between the safety ball 34 and the spiral raceway 11, and further reducing the impact of the safety nut mechanism 3 on the normal operation of the transmission nut mechanism 2. In addition, the oil in the limiting hole 32 can also play a certain buffering role for the safety ball 34, further improving the shock absorption effect.

[0033] Further improvement, the embodiment preferably that the limiting hole 32 penetrates the inner and outer sidewalls of the safety nut seat 31, the safety ball 34 blocks the outlet of the limiting hole 32 close to the center screw 1, the inlet of the limiting hole 32 away from the center screw 1 is detachably installed with the plunger 36, the plunger 36 blocks the inlet of the limiting hole 32, the elastic buffer 33 is located between the plunger 36 and the safety ball 34, the design of the limiting hole 32 penetration and the plunger 36 can facilitate the installation of the elastic buffer 33 and the safety ball 34, and also facilitate the filling of oil; during installation, first install the safety nut seat 31, then put the safety ball 34 and the elastic buffer 33 into the limiting hole 32 in turn, then fill the oil, and finally install the plunger 36 in the inlet of the limiting hole 32 to block it, which is very convenient to install, without the need to manufacture the elastic buffer 33, the safety ball 34 and the safety nut seat 31 together at the time of production, which reduces the manufacturing cost and maintenance cost; during use, the oil will continue to be lost, when the oil needs to be added, the plunger 36 is removed, then the oil is supplemented and filled, and the plunger 36 is installed again for continuous use. Preferably, the plunger 36 and the limiting hole 32 are threadedly connected.

[0034] The spiral teeth 35 effectively improve the locking ability of the safety nut mechanism 3, but in actual operation, the linear driver still needs to run under the action of the safety nut mechanism 3 to complete the current lifting task or to drop to a safe height, so under the action of the driving force, the spiral teeth 35 on the safety nut mechanism 3 need to slide along the spiral raceway 11 to realize the travel of the safety nut mechanism 3. The embodiment preferably that the safety nut seat 31 and the transmission nut mechanism 2 have a gap and form an oil supplement cavity 38, the oil supplement cavity 38 surrounds the center screw 1, the safety nut seat 31 is provided with a transfer hole 37 communicating the limiting hole 32 and the oil supplement cavity 38, the limiting hole 32, the transfer hole 37 and the oil supplement cavity 38 are filled with oil during oil filling, the oil in the oil supplement cavity 38 directly flows into the spiral raceway 11 of the center screw 1, reducing the friction between the spiral teeth 35 and the spiral raceway 11, so that the safety nut mechanism 3 can more easily travel along the center screw 1 under the driving of the driving force.

[0035] The embodiment preferably arranges the limiting hole channels 32 in a circumferential array along the circumference of the safety nut seat 31, which refers to the planar arrangement of the limiting hole channels 32 in the axial view of the central screw 1. In fact, the limiting hole channels 32 can have a spacing in the axial direction of the central screw 1, and are not in one cross section. The embodiment is further improved, and preferably, the outlets of all the limiting hole channels 32 are arranged on the spiral top teeth 35 along the spiral extension direction of the spiral top teeth 35. Thus, all the safety balls 34 are also arranged along the spiral extension direction of the spiral top teeth 35. Therefore, the safety balls 34 and the spiral top teeth 35 are combined to jointly play their respective roles at the same position of the spiral raceway 11, and simultaneously play the axial and lateral locking roles at the same position, thereby improving the locking effect. In the embodiment, the elastic buffer 33 is a spring, the diameter of the spring is smaller than the diameter of the safety ball 34, and the spring and the safety ball 34 do not need to have a connection relationship, but can directly abut against each other to interact with each other, which is convenient for installation and has good force transmission effect.

[0036] The aerial work platform of the application comprises the linear driver with the contact type safety nut, and the safety nut mechanism 3 in the linear driver is safe and stable and has no loss of precision when it works, so that the aerial work platform can be safe and stable and have good precision when it encounters a linear driver failure. The aerial work platform can be a commonly used aerial work platform such as a scissor-type aerial work platform and an aerial work platform with a loading platform.

[0037] Embodiment two

[0038] The scissor-type lifting device with the hydraulic buffer 5 for maintenance of the application comprises the hydraulic buffer 5 and the scissor mechanism 4. The hydraulic buffer 5 comprises a hydraulic cylinder 51 and a piston rod 52. The hydraulic cylinder 51 has a lower connecting end 6, and the piston rod 52 has an upper connecting end 7. The hydraulic buffer 5 can support the scissor mechanism 4 after the upper connecting end 7 and the lower connecting end 6 are connected to the scissor mechanism 4. The hydraulic buffer 5 is used for support. When the scissor mechanism 4 exerts pressure on the hydraulic buffer 5, the piston rod 52 is gradually pressed into the hydraulic cylinder 51. In this process, the hydraulic buffer 5 has the characteristics of strong buffering capacity and strong load capacity. The hydraulic buffer 5 is safe and stable when it supports the scissor mechanism 4, and can resist impact by using the buffering performance, so as to avoid damage to itself and the scissor mechanism 4. In addition, the maximum load value can be large, and in actual maintenance, the hydraulic buffer 5 can be used for support only, without starting the lifting mechanism 9 to provide additional support force. In the long maintenance process, energy can be saved effectively. In the embodiment, the hydraulic buffer 5 has the lower connecting end 6 and the upper connecting end 7 specially connected to the scissor mechanism 4, and the connection is firm and safe.

[0039] The scissors mechanism 4 includes two groups of scissors frames 42 in front and back, and a cross support 41 arranged between the two groups of scissors frames 42 and arranged in the up-down direction on the left and right sides of the scissors mechanism 4; when the scissors frame 42 is unfolded, the cross supports 41 on the same side are away from each other in the up-down direction, and when the scissors frame 42 is contracted, the cross supports 41 on the same side are close to each other in the up-down direction; the hydraulic buffer 5 is arranged between two cross supports 41 adjacent in the up-down direction in the middle cross support 41 on one side, and is connected with the cross support 41 above through the upper connecting end 7, and is connected with the cross support 41 below through the lower connecting end 6, and supports the two cross supports 41 to support the entire scissors mechanism 4. The hydraulic buffer 5 can be damaged, and the load capacity of the hydraulic buffer 5 required for different actual situations is different, and both of these two conditions need to replace the hydraulic buffer 5, so the connection form between the lower connecting end 6 and the cross support 41 in the embodiment is detachable fixing.

[0040] The specific connection form between the hydraulic buffer 5 and the cross support 41, the lower connecting end 6 in the embodiment preferably includes a lower arc-shaped seat 61, the lower arc-shaped seat 61 has a lower arc-shaped groove 62 capable of completely abutting on the outer wall of the cross support 41 to realize clamping; both ends of the lower arc-shaped seat 61 are rotatably connected with a lower opening and closing part 63, the lower opening and closing part 63 is arc-shaped and can completely abut on the outer wall of the cross support 41, the ends of the two lower opening and closing parts 63 are connected with a lower fastener 81, the lower fastener 81 can pull the ends of the two lower opening and closing parts 63 towards each other to realize locking. The lower arc-shaped seat 61 is an integral molded part, and has high structural strength, and plays a main clamping support role, the cross support 41 is a circular rod, the shape of the lower arc-shaped groove 62 is matched with the shape of the outer wall of the cross support 41, the lower arc-shaped seat 61 semi-encloses the cross support 41 through the lower arc-shaped groove 62, and the clamping relationship is very stable and reliable; the lower opening and closing part 63 completely clamps the cross support 41, and further improves the engagement firmness, and the lower fastener 81 has a force of pulling the ends of the two lower opening and closing parts 63 towards each other when locking, so that the two lower opening and closing parts 63 clamp the cross support 41. During installation, the two lower opening and closing parts 63 are in an open state, the lower arc-shaped seat 61 is clamped with the cross support 41, then the two lower opening and closing parts 63 clamp the cross support 41, and the lower fastener 81 is locked.

[0041] If the two lower open-close parts 63 are in contact after clamping the horizontal support rod 41, interference actually exists between the two ends, and no matter how the lower fastener 81 increases the locking force, it is difficult to act on the two lower open-close parts 63. Therefore, in this embodiment, preferably, after the two lower open-close parts 63 are completely attached to the outer wall of the horizontal support rod 41, a gap is provided between the two ends of the two lower open-close parts 63. In this way, when the lower fastener 81 increases the locking force, the clamping force between the lower open-close part 63 and the horizontal support rod 41 can be improved, and the locking effect is further improved. After locking, the lower connecting end 6 is difficult to move relative to the horizontal support rod 41, so it can be considered to be in a fixed state. The end of the lower open-close part 63 has a mounting piece 64 for mounting the lower fastener 81. The mounting piece 64 is vertically arranged, and the locking force generated by the lower fastener 81 is perpendicular to the mounting piece 64. The lower fastener 81 pulls the two mounting pieces 64, improving the transmission effect of the locking force of the lower fastener 81, and further improving the locking effect. Preferably, the lower fastener 81 includes a bolt and a nut. The mounting piece 64 is provided with a through hole for the bolt to pass through. The bolt is simultaneously arranged in the through holes of the two mounting pieces 64, and then the nut is tightened to generate the locking force.

[0042] In this embodiment, the upper connecting end 7 includes an upper arc-shaped seat 71, which has an upper arc-shaped groove 72 capable of being completely attached to the outer wall of the horizontal support rod 41 to achieve clamping. Both ends of the upper arc-shaped seat 71 are rotationally connected with an upper open-close part 73, which is arc-shaped and capable of being completely attached to the outer wall of the horizontal support rod 41. The ends of the two upper open-close parts 73 are connected with an upper fastener 82, which can pull the ends of the two upper open-close parts 73 towards each other to achieve locking. The functions of the upper arc-shaped seat 71, the upper open-close part 73, and the upper fastener 82 are the same as those of the lower arc-shaped seat 61, the lower open-close part 63, and the lower fastener 81, respectively. The installation principle is also the same. Of course, it can be further preferred that the ends of the two upper open-close parts 73 also have a gap after clamping the horizontal support rod 41, and the ends of the two upper open-close parts 73 both have a mounting piece 64 for mounting the upper fastener 82 to better exert the locking effect of the upper fastener 82. The composition of the upper fastener 82 is the same as that of the lower fastener 81.

[0043] The hydraulic bumper 5 is only used when the equipment is maintained, and the hydraulic bumper 5 does not work when the forklift is in normal operation. The lower connecting end 6 and the upper connecting end 7 can be directly removed, but there is usually no extra space to place the hydraulic bumper 5, and it is too cumbersome to disassemble every time it is used. Therefore, the embodiment preferably has an opening upwardly arranged on the side wall of one of the fork frames 42 towards the other fork frame 42, and the lower connecting end 6 can move along the horizontal support rod 41 towards the fork frame 42 with the storage box when the lower fastener 81 is loosened. The lower fastener 81 can rotate relative to the horizontal support rod 41, so that the hydraulic bumper 5 falls into the storage box. In use, the hydraulic bumper 5 is usually located in the middle position of the horizontal support rod 41 for better support, and the storage box is arranged on the side wall of the fork frame 42, which is a direct fixed connection relationship. The closer the closer, the higher the firmness, and interference with the lifting mechanism 9 can be avoided. Therefore, when the hydraulic bumper 5 is stored, the upper connecting end 7 is first disengaged from the horizontal support rod 41, then the nut in the lower fastener 81 is loosened, so that the lower opening and closing part 63 no longer tightly grips the horizontal support rod 41, and the lower connecting end 6 can move or rotate relative to the horizontal support rod 41. First move towards the fork frame 42 with the storage box until the hydraulic bumper 5 is aligned with the storage box, then rotate the lower connecting end 6 relative to the horizontal support rod 41, and the hydraulic bumper 5 falls into the storage box to achieve storage. Further, the opening of the storage box is preferably provided with a detachable cover plate, and when the hydraulic bumper 5 is stored in the storage box, the cover plate is installed to avoid the hydraulic bumper 5 from being separated from the storage box, which affects the normal operation of the equipment.

[0044] In order to avoid impurities entering the hydraulic cylinder 51 through the gap and affecting the normal operation of the hydraulic cylinder 51, the hydraulic buffer 5 of the embodiment preferably further comprises a dust cover 53 sleeved on one end of the hydraulic cylinder 51, the dust cover 53 is fixed on the piston rod 52, the dust cover 53 can move relative to the hydraulic cylinder 51 following the piston rod 52, the dust cover 53 circumferentially surrounds one end of the hydraulic cylinder 51, is sealed on one axial side and is fixed with the piston rod 52, and is open on the other axial side and allows the hydraulic cylinder 51 to extend into. In this way, the dust cover 53 can prevent impurities from entering the hydraulic cylinder 51. The hydraulic buffer cylinder has a maximum load capacity, and if the load capacity is exceeded, the hydraulic buffer cylinder will be damaged and fail. Therefore, the outer wall of the hydraulic cylinder 51 is provided with a warning scale, and when the dust cover 53 moves, a visible distance change occurs between the lower edge of the dust cover 53 and the warning scale. When the lower edge of the dust cover 53 reaches the warning scale, the hydraulic buffer 5 reaches the maximum load capacity. When using the hydraulic buffer 5, first use the lifting mechanism 9 to lift the scissor mechanism 4, so that the distance between the two adjacent upper and lower horizontal support rods 41 is greater than the total length of the hydraulic buffer 5 in the initial state. Then, the hydraulic buffer 5 is lifted from the storage box, and the upper horizontal support rod 41 is placed in the upper arc groove 72 in the upper arc seat 71 of the upper connecting end 7. Then, the lowering function module of the lifting mechanism 9 is started to drive the scissor mechanism 4 to shrink and descend, so that the horizontal support rod 41 enters the upper arc groove 72, and the hydraulic buffer 5 continues to descend to support the horizontal support rod 41. During the continuous descending process, the lifting mechanism 9 needs to be stopped in time before the lower edge of the dust cover 53 exceeds the warning scale, so as to avoid damage to the hydraulic buffer 5. In this way, only the scissor mechanism 4 presses on the hydraulic buffer 5, which is usually the load that the hydraulic buffer 5 can withstand.

[0045] However, in actual operation, the operator may forget to turn off the lifting mechanism 9 due to carelessness, and the lifting mechanism 9 continues to descend. The hydraulic buffer 5 bears the pressure of the scissor mechanism 4 and the thrust of the lifting mechanism 9. When the lower edge of the dust cover 53 exceeds the warning scale, the hydraulic buffer 5 is damaged. Therefore, the scissor lifting device of the embodiment preferably further comprises a lifting mechanism 9, a controller, and a switch. The lifting mechanism 9 supports the scissor mechanism 4 and has a lifting function module and a lowering function module that can drive the scissor mechanism 4 to extend or shrink. The switch is arranged on the hydraulic buffer 5, and the lower edge of the dust cover 53 can trigger the switch when it reaches the warning scale. The controller can receive the signal of the switch and control the lifting mechanism 9 to stop the descending action, so as to avoid damage to the hydraulic buffer 5. The lifting mechanism 9 uses the linear driver with a contact safety nut described in Embodiment 1.

[0046] Based on the above-mentioned scissor lift device with a maintenance hydraulic buffer 5, the present application proposes a control method of a scissor lift device with a maintenance hydraulic buffer 5, in particular a control method during maintenance, comprising the following steps:

[0047] S01: Start the lifting function module of the lifting mechanism 9 to drive the scissor mechanism 4 to extend until the distance between the two adjacent horizontal support rods 41 in the up-down direction exceeds the total length of the hydraulic buffer 5 in the initial state;

[0048] S02: Take out the hydraulic buffer 5 from the storage position and support it upwards, so that the upper connecting end 7 of the hydraulic buffer 5 is aligned with the horizontal support rod 41 of the scissor mechanism 4;

[0049] S03: Start the descending function module of the lifting mechanism 9 to drive the scissor mechanism 4 to contract, and the horizontal support rod 41 located above the hydraulic buffer 5 and closest to the upper connecting end 7 moves towards the upper connecting end 7 until it is engaged with the upper connecting end 7;

[0050] S04: The lifting mechanism 9 continues to drive the scissor mechanism 4 to contract, the horizontal support rod 41 presses the hydraulic buffer 5, the hydraulic buffer 5 gradually contracts, and the lower edge of the dust cover 53 gradually approaches the warning scale;

[0051] S05: Before the lower edge of the dust cover 53 exceeds the warning scale, turn off the descending function module of the lifting mechanism 9 to stop the contraction of the scissor mechanism 4, and the hydraulic buffer 5 supports the scissor mechanism 4.

[0052] For further improvement of the above-mentioned step S05, when the lower edge of the dust cover 53 reaches the warning scale in step S05, the dust cover 53 triggers the switch, and the controller controls the lifting mechanism 9 to turn off the descending function module after receiving the signal of the switch.

[0053] Further improvement, after step S05, there is also step S06, after the descending function module of the lifting mechanism 9 is turned off, the controller controls the lifting mechanism 9 to start the lifting function module, the support force output by the lifting function module can maintain the static state of the scissor mechanism 4 together with the hydraulic buffer 5, reducing the burden of the hydraulic buffer 5, and even in the extreme case of sudden failure of the hydraulic buffer 5, the lifting mechanism 9 can also play a supporting role, further ensuring safety.

[0054] The above control method utilizes the lifting mechanism 9, so it is suitable for the case of repairing parts other than the lifting mechanism 9. If the lifting mechanism 9 needs to be repaired, another control method is required. The present application is a control method for a scissor lifting device with a hydraulic buffer 5 for maintenance, comprising the following steps:

[0055] S01: Pull up the scissor mechanism 4 to stretch it until the distance between the two adjacent horizontal support rods 41 exceeds the total length of the hydraulic buffer 5 in the initial state;

[0056] S02: Take the hydraulic buffer 5 out of the storage position and hold it up, aligning the upper connecting end 7 of the hydraulic buffer 5 with the horizontal support rod 41 of the scissor mechanism 4;

[0057] S03: Keep pulling up the scissor mechanism 4 and gradually lower it using the pulling force, causing the scissor mechanism 4 to contract, the horizontal support rod 41 closest to the upper connecting end 7 above the hydraulic buffer 5 to move towards the upper connecting end 7 until it is engaged with the upper connecting end 7;

[0058] S04: As the scissor mechanism 4 continues to contract, the hydraulic buffer 5 gradually supports the horizontal support rod;

[0059] S05: Remove the pulling force to make the scissor mechanism 4 fully supported by the hydraulic buffer 5.

[0060] The pulling force in the control method is provided by the suspension device.

[0061] The above is only a specific embodiment of the present application, but the scope of protection of the present application is not limited to this. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be covered within the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. Linear drive with a contact safety nut, characterized in that The device comprises a central screw (1), a transmission nut mechanism (2) and a safety nut mechanism (3), the central screw (1) has a spiral raceway (11), the safety nut mechanism (3) comprises a safety nut seat (31) sleeved on the periphery of the central screw (1), the safety nut seat (31) is provided with a limiting hole (32) pointing to the central screw (1), the limiting hole (32) is provided with an elastic buffer (33), the elastic buffer (33) and the central screw (1) are provided with a safety ball (34), the safety ball (34) is partially in the spiral raceway (11) and partially in the limiting hole (32), the safety ball (34) can roll along the spiral raceway (11) and can move along the limiting hole (32); the safety nut seat (31) is provided with a plurality of limiting holes (32) in the circumferential direction, and the limiting hole (32) is provided with the elastic buffer (33) and the safety ball (34). The inner wall of the safety nut seat (31) has a spiral top tooth (35), the spiral top tooth (35) extends into the spiral raceway (11) and is spaced apart from the central screw (1); when the transmission nut mechanism (2) is in normal operation, the spiral top tooth (35) does not contact the central screw (1); when the transmission nut mechanism (2) fails, the spiral top tooth (35) is pressed in the spiral raceway (11) of the central screw (1), so that the spiral top tooth (35) directly presses the central screw (1) laterally; The limiting hole (32) is filled with oil, the cross-sectional diameter of the limiting hole (32) is consistent with the diameter of the safety ball (34), the outer circle of the safety ball (34) completely abuts against the inner wall of the limiting hole (32), the safety ball (34) is clamped in the limiting hole (32), and the movement of the safety ball (34) in the limiting hole (32) is fully limited by the limiting hole (32); The limiting hole (32) penetrates the inner and outer side walls of the safety nut seat (31), the safety ball (34) blocks the outlet of the limiting hole (32) close to the central screw (1), and the inlet of the limiting hole (32) away from the central screw (1) is detachably provided with a plunger (36), the plunger (36) blocks the inlet of the limiting hole (32), and the elastic buffer (33) is located between the plunger (36) and the safety ball (34); The safety nut seat (31) and the transmission nut mechanism (2) have a gap and form an oil supplement cavity (38), the oil supplement cavity (38) surrounds the central screw (1), and the safety nut seat (31) is provided with a transfer hole (37) communicating the limiting hole (32) and the oil supplement cavity (38).

2. Linear drive with contact safety nut according to claim 1, characterized in that The limiting hole (32) is arranged in a circumferential array along the circumference of the safety nut seat (31).

3. Linear drive with contact safety nut according to claim 2, characterized in that The outlets of all the limiting holes (32) are arranged on the spiral top teeth (35) along the spiral extension direction of the spiral top teeth (35).

4. Linear drive with contact safety nut according to claim 1, characterized in that The elastic buffer (33) is a spring, and a diameter of the spring is smaller than a diameter of the safety ball (34).

5. An aerial work platform, characterized in that, A linear drive with a contact safety nut according to any one of claims 1-4.

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