A lifting device

Abstract

The utility model discloses a lifting device, be applied to lifting equipment technical field, include: inner arm support, the lower extreme of inner arm support is equipped with the machine base, middle arm support, coaxial sleeve is established in the outer periphery of inner arm support, middle arm support can along the axial lifting of inner arm support, outer arm support, coaxial sleeve is established in the outer periphery of middle arm support, the cavity is equipped between the inner wall of outer arm support and the outer wall of middle arm support, and outer arm support can along the axial lifting of middle arm support, drive mechanism, locate in the cavity, drive mechanism is used for driving outer arm support lifting, linkage mechanism, one end connects outer arm support, and the other end connects middle arm support, linkage mechanism is used for when driving middle arm support synchronous lifting with outer arm support lifting, and the lifting speed of outer arm support is greater than the lifting speed of middle arm support. Under the prerequisite of not increasing the whole machine contraction size, realize greater lifting stroke.

Description

Technical Field

[0001] This utility model relates to the field of lifting equipment technology, and in particular to a lifting device. Background Technology

[0002] Existing lifting devices generally adopt a two-section telescopic boom structure, with hydraulic cylinders or electric push rods directly driving the boom to extend and retract to achieve lifting. This type of solution is limited by the number of sections, resulting in a short single-stage stroke and insufficient total lifting height; the drive mechanism directly bears the entire load, leading to high stress and rapid wear on the gears, racks, or push rods, thus limiting the rated load; the boom is mostly driven at a single point, and the guide length shortens sharply with the extension height, reducing lateral stiffness and significantly increasing platform sway, affecting operational safety and comfort.

[0003] Therefore, there is an urgent need for a new type of lifting device that can achieve a greater lifting height and stronger load-bearing capacity with the same folded size, which is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0004] The purpose of this invention is to provide a lifting device that can achieve a greater lifting stroke without increasing the overall size of the machine when folded up.

[0005] To solve the above-mentioned technical problems, this utility model provides a lifting device, comprising:

[0006] An inner boom frame, the lower end of which is provided with a base;

[0007] The middle boom is coaxially sleeved on the outer periphery of the inner boom, and the middle boom can be raised and lowered along the axial direction of the inner boom;

[0008] An outer boom is coaxially sleeved on the outer periphery of the middle boom. A cavity is provided between the inner wall of the outer boom and the outer wall of the middle boom. The outer boom can be raised and lowered along the axial direction of the middle boom.

[0009] A drive mechanism is located inside the cavity, and the drive mechanism is used to drive the outer boom to lift and lower.

[0010] The linkage mechanism is connected to the outer boom at one end and the middle boom at the other end. The linkage mechanism is used to drive the middle boom to rise and fall synchronously when the outer boom is raised and lowered, and the raising and lowering speed of the outer boom is greater than that of the middle boom.

[0011] Optionally, the linkage mechanism includes:

[0012] A pulley is provided on the central boom, and the pulley is located inside the cavity;

[0013] A connecting rope, the middle of which is wrapped around the pulley, and the two ends of which are fixed to the inner wall of the outer boom and the outer wall of the middle boom, respectively.

[0014] Optionally, the linkage mechanism has no less than two sets; at least one set of pulleys is located at the lower end of the middle boom, and at least another set of pulleys is located at the upper end of the middle boom.

[0015] Optionally, the drive mechanism includes a drive wheel, a pulley, and a timing belt surrounding both; the drive wheel's shaft is rotatably supported on the boom, and the pulley's shaft is fixedly connected to the boom.

[0016] Optionally, the drive mechanism further includes:

[0017] The first gear is coaxially fixedly connected to the pulley;

[0018] The second gear meshes with the first gear, and the shaft of the second gear is fixed to the outer boom.

[0019] The third gear meshes with the second gear, and the shaft of the third gear is fixed to the outer boom.

[0020] Two racks are arranged vertically at intervals on the central boom, and the second gear and the third gear respectively mesh with the two racks.

[0021] Optionally, the middle boom is fixed with an upper stop block and a lower stop block above and below the rack, respectively; the outer boom is correspondingly provided with an upper limit block and a lower limit block. When the upper limit block abuts against the upper stop block, the middle boom and the outer boom simultaneously reach the highest limit position. When the lower limit block abuts against the lower stop block, the bottom surfaces of the middle boom and the outer boom simultaneously sit on the base, forming the lowest limit position.

[0022] Optionally, the inner boom has a chamber inside, in which a drive cylinder is installed. The cylinder body end of the drive cylinder is hinged to the base, and the piston rod end extends upward and is hinged to the top of the outer boom. The drive cylinder extends and retracts synchronously with the lifting and lowering of the outer boom.

[0023] Optionally, the minimum stroke of the drive cylinder corresponds to the lowest limit position of the boom, and the maximum stroke of the drive cylinder corresponds to the highest limit position of the boom.

[0024] Optionally, a centrifugal pawl is hinged to the rim of the second gear or the third gear. When the second gear or the third gear stops rotating, the centrifugal pawl is thrown out by inertia and engages with the corresponding tooth of the rack.

[0025] Optionally, front and rear limiting components and left and right limiting components are provided in the gap between the cavity, the outer wall of the inner boom and the inner wall of the middle boom, to constrain the lateral and longitudinal displacement of each boom.

[0026] The lifting device provided by this utility model has a middle boom coaxially sleeved around the outer periphery of the inner boom, and an outer boom coaxially sleeved around the outer periphery of the middle boom. The drive mechanism drives the outer boom, which directly receives the driving thrust. Simultaneously, a portion of the displacement is transmitted to the middle boom in a multiplicative manner through a linkage mechanism, causing the middle boom to rise synchronously, but at a lower linear velocity than the outer boom. This creates a differential lifting motion where the outer boom is faster and the inner boom is slower. Conversely, when the drive mechanism runs in the opposite direction, the linkage mechanism transmits the descending motion to the middle boom at the same multiplicative speed, ensuring that the outer boom and middle boom retract synchronously.

[0027] Compared to existing technologies, the advantages of this invention lie in the fact that the inner boom, middle boom, and outer boom form a three-layered, nested telescopic column. The drive mechanism applies a unidirectional thrust to the outer boom, which automatically drives the middle boom to extend and retract via the mechanical coupling of the linkage mechanism, eliminating the need for an additional power source for the middle boom. The differential speed relationship achieves a greater extension height at the same retracted height; compared to the two-section boom in existing technologies, the three-section boom design achieves a significantly increased lifting stroke while maintaining the same retracted dimensions. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 A schematic diagram of the lifting device provided in a specific embodiment of this utility model;

[0030] Figure 2 Here is another schematic diagram of the lifting device;

[0031] Figure 3 for Figure 2 A magnified view of a section at point D;

[0032] Figure 4 This is a schematic diagram of the drive mechanism;

[0033] Figure 5 Another schematic diagram of the drive mechanism;

[0034] Figure 6 A schematic diagram showing the connections of each boom;

[0035] Figure 7 This is a schematic diagram of the transmission on the inner side of the outer boom.

[0036] Figure 8 for Figure 7 A magnified view of a section at point A in the middle;

[0037] Figure 9 for Figure 7 A magnified view of a section at point B in the middle;

[0038] Figure 10 This is a schematic diagram of the rack structure;

[0039] Figure 11 for Figure 10 A magnified view of a section at point C.

[0040] Figure label:

[0041] 1-Drive wheel; 2-Handle; 3-Synchronous belt; 4-Tensioner; 5-Rack; 6-Third gear; 7-Second gear; 8-Pulley; 9-First gear; 10-Pulley; 11-Inner boom; 12-Middle boom; 13-Outer boom; 14-Connecting rope; 15-Chain; 16-Roller; 17-Drive cylinder. Detailed Implementation

[0042] The core of this utility model is to provide a lifting device that achieves a greater lifting stroke without increasing the overall size of the machine when folded up.

[0043] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0044] In one specific embodiment provided by this utility model, please refer to... Figures 1-11 The lifting device mainly includes an inner boom 11, a middle boom 12, an outer boom 13, a drive mechanism, and a linkage mechanism.

[0045] The lower end of the inner boom 11 is equipped with a base;

[0046] The middle boom 12 is coaxially sleeved on the outer periphery of the inner boom 11, and the middle boom 12 can be raised and lowered along the axial direction of the inner boom 11.

[0047] The outer boom 13 is coaxially sleeved on the outer periphery of the middle boom 12. A cavity is provided between the inner wall of the outer boom 13 and the outer wall of the middle boom 12. The outer boom 13 can be raised and lowered along the axial direction of the middle boom 12.

[0048] The drive mechanism is located inside the cavity and is used to drive the outer boom 13 to lift.

[0049] The linkage mechanism is connected to the outer boom 13 at one end and the middle boom 12 at the other end. The linkage mechanism is used to drive the middle boom 12 to lift synchronously when the outer boom 13 is lifted and lowered, and the lifting speed of the outer boom 13 is greater than the lifting speed of the middle boom 12.

[0050] It should be noted that the lower end of the inner boom 11 is provided with a base, which is fixed to the ground or a moving platform by anchor bolts or welding, providing a static reference for the entire lifting device. The middle boom 12 is coaxially sleeved on the outer periphery of the inner boom 11, with an annular sliding gap between them. Preferably, a linear guide rail or wear-resistant slide bar is provided in this gap, allowing the middle boom 12 to slide up and down without deviation along the axial direction of the inner boom 11. At the same time, dustproof sealing rings are embedded at the upper and lower ends of the sliding surface to prevent dust from entering the sliding interface. The outer boom 13 is coaxially sleeved on the outer periphery of the middle boom 12, with a cavity between its inner wall and the outer wall of the middle boom 12. This cavity is closed circumferentially and runs vertically through, providing installation and operating space for the drive mechanism and linkage mechanism. The closed annular layout of the cavity covers the drive mechanism and linkage mechanism, preventing the intrusion of external dust and moisture, and reducing the risk of personnel contact. Preferably, the outer boom 13 is also slidably engaged with the middle boom 12 via a linear guide element, allowing it to rise and fall along the axial direction of the middle boom 12, and ensuring that the outer boom 13 and the middle boom 12 remain coaxial during the lifting process. Each boom maintains sufficient overlap throughout its movement, and the guide surface covers the load application area, resulting in uniform lateral force distribution, higher overall rigidity, and smoother operation.

[0051] The drive mechanism is housed within the cavity, with its fixed end connected to the outer boom 13. The motion of the drive end is converted into linear motion, directly propelling the outer boom 13 to rise and fall relative to the middle boom 12. One end of the linkage mechanism is hinged or bolted to the inner wall of the outer boom 13, and the other end is hinged or bolted to the outer wall of the middle boom 12, forming a closed force transmission chain. That is, the outer boom 13 directly receives the driving thrust, and simultaneously, through the linkage mechanism, a portion of the displacement is transmitted to the middle boom 12 in a multiplied manner, causing the middle boom 12 to rise synchronously, but at a lower linear velocity than the outer boom 13, thus creating a differential lifting motion where the outer boom 13 is faster and the inner boom 11 is slower. Conversely, when the drive mechanism operates in the opposite direction, the linkage mechanism transmits the descending motion to the middle boom 12 at the same multiplied speed, ensuring that the outer boom 13 and the middle boom 12 retract synchronously.

[0052] With the above structure, the inner boom 11, middle boom 12, and outer boom 13 form a three-layered, nested telescopic column. The drive mechanism applies a unidirectional thrust to the outer boom 13, which automatically drives the middle boom 12 to extend and retract via the mechanical coupling of the linkage mechanism, eliminating the need for an additional power source for the middle boom 12. The differential speed relationship achieves a greater extension height at the same retracted height; compared to the two-section boom in the prior art, the three-section boom design achieves a significantly increased lifting stroke while maintaining the same retracted dimensions.

[0053] In some embodiments, the linkage mechanism consists of a pulley 10 and a connecting rope 14, both of which are concealed within the cavity between the middle boom 12 and the outer boom 13, without occupying additional external space or affecting the boom's retracted dimensions. The pulley 10 is fixed to the middle boom 12 via a short shaft perpendicular to the axis of the middle boom 12. A reinforcing rib may be provided at the root of the short shaft to ensure the pulley 10 remains axially stable under bidirectional tension. The pulley 10 has convex edges on both sides of its rim, forming a U-shaped rope groove to constrain the lateral position of the connecting rope 14 and prevent it from slipping out of the groove during lifting. A polyurethane ring is embedded at the bottom of the rope groove of the pulley 10. The surface friction coefficient of the polyurethane ring is higher than that of the pulley 10 base, used to suppress micro-slippage of the connecting rope 14. The connecting rope 14 is preferably made of flexible steel wire rope with minimal tensile deformation. The middle of the connecting rope 14 originates from either the upper or lower end of the pulley 10, and both ends extend in opposite directions to wrap around the pulley 10. The two ends are respectively fixed to the inner wall of the outer boom 13 and the outer wall of the middle boom 12, forming a folded return path. The fixed end of the connecting rope 14 can be connected by a chain 15, or it can be an adjustable rope head assembly consisting of a pressure plate, wedge sleeve, and locking screw. This facilitates tensioning during installation and allows for readjustment after long-term use, eliminating slack caused by creep.

[0054] When the drive mechanism pushes the outer boom 13 upward, the outer boom 13 generates relative displacement with respect to the middle boom 12, and the connecting rope 14 is pulled synchronously. Since the pulley 10 is fixed on the middle boom 12, the folded return structure of the connecting rope 14 allows the middle boom 12 to achieve approximately twice the rope pulling stroke, thus realizing a differential effect where the speed of the outer boom 13 is higher than that of the middle boom 12. Conversely, when the outer boom 13 descends, the connecting rope 14 loosens, and the middle boom 12 retracts synchronously under its own weight or the action of the reset element, preventing slackness caused by one side. The pulley 10 and the connecting rope 14 are located entirely within a closed cavity, preventing external impurities from entering the rope groove, allowing the lubricant to be retained for a long time, significantly reducing wear and noise; at the same time, the rope force acts on the boom wall without generating additional bending moment, making the overall structure compact, with reasonable force distribution, and smooth operation.

[0055] In some embodiments, the linkage mechanism is configured with no fewer than two sets, each set of linkage mechanisms being distributed circumferentially to form a symmetrical tension structure. At least one set of pulleys 10 is installed at the lower end of the boom 12, with both ends of its connecting rope 14 located above the pulleys 10, mainly bearing the tension side load during the upward stroke. At least another set of pulleys 10 is installed at the upper end of the boom 12, with both ends of its connecting rope 14 located below the pulleys 10, mainly bearing the retraction side load during the downward stroke, so that the boom 12 obtains bidirectional balanced force throughout its entire stroke.

[0056] For example, the short shafts of the lower pulley 10 and the upper pulley 10 pass horizontally through the reinforcing plate at the bottom of the middle boom 12, and shoulder retaining rings are added on both sides to allow the pulley 10 to rotate freely without axial movement. The lower pulley 10 has one end of its connecting rope 14 fixed to the lower region of the inner wall of the outer boom 13, and the other end wraps downwards around the pulley 10 and then turns upwards, finally fixing to the upper region of the middle boom 12, forming an upper tension arm. The upper pulley 10 has one end of its connecting rope 14 fixed to the upper region of the inner wall of the outer boom 13, and the other end wraps upwards around the pulley 10 and then turns downwards, finally fixing to the lower region of the middle boom 12, forming a lower tension arm. The two sets of pulleys 10 and their connecting ropes 14 can be arranged spatially and cross each other within the cavity, or located on the left and right sides of the cavity respectively, avoiding interference between rope segments and ensuring that the middle boom 12 is simultaneously subjected to two sets of rope forces of opposite direction and equal magnitude.

[0057] When the drive mechanism pushes the outer boom 13 upward, the connecting rope 14 at the lower fixed point of the outer boom 13 is first tightened, transmitting the tension force to the middle boom 12. Simultaneously, the connecting rope 14 at the upper fixed point of the outer boom 13 relaxes, forming differential following. During descent, the connecting rope 14 at the upper fixed point of the outer boom 13 becomes tensioned again, transmitting the contraction force to the middle boom 12. Correspondingly, the connecting rope 14 at the lower fixed point of the outer boom 13 relaxes, maintaining symmetrical movement. The alternating upward and downward action ensures that the middle boom 12 experiences balanced force throughout its entire lifting stroke, effectively suppressing uncontrollable, skewed, or jammed movements caused by unilateral tension. Simultaneously, the elongation of each set of connecting ropes 14 can compensate for each other, and the pulleys 10 maintain consistent rotational speed, thereby achieving synchronous lifting and lowering of the middle boom 12 and the outer boom 13, further improving the overall stability and reliability of the movement.

[0058] In a preferred embodiment, the pulley 10 of each linkage mechanism is a coaxial double-groove pulley. The middle part of the connecting rope 14 is wound in parallel around the two grooves of the double-groove pulley, and the two ends are respectively fixed to the inner wall of the outer boom 13 and the outer wall of the middle boom 12.

[0059] It should be noted that each linkage mechanism preferably uses a coaxial double-groove pulley, that is, two parallel rope grooves are machined on the same hub, with a rim partition between the two grooves. The partition is thick enough to isolate the rope forces in the two grooves and also allows the connecting rope 14 to wind smoothly in the same plane. The hub of the pulley 10 is fixed to the middle boom 12 by a short shaft. A reinforcing rib is provided at the root of the short shaft. This reinforcing rib is integrally formed with the middle boom 12 and can withstand the bidirectional tension transmitted from the double grooves, preventing the short shaft from bending and deforming. The connecting rope 14 first winds through the first groove of the double-groove pulley, then turns back, and then winds through the second groove, forming a double-turnback path. The rope segments between the two grooves are parallel and have equal tension, keeping the pulley 10 in force balance and preventing lateral overturning. When the outer boom 13 moves relative to the middle boom 12, the connecting rope 14 is pulled synchronously. Since the double-groove pulley is fixed, the double-turnback structure allows the middle boom 12 to obtain a stroke twice that of the rope end displacement, thereby realizing differential lifting.

[0060] In a preferred embodiment, a torsion spring tension arm is disposed adjacent to one side of the pulley 10. This torsion spring tension arm consists of a torsion spring, a rocker arm, and a roller sleeve. The torsion spring is sleeved on the extended end of the short shaft, with its fixed end connected to the end cap of the short shaft and its movable end fixed to the root of the rocker arm. A freely rotatable roller sleeve is installed at the end of the rocker arm, and the outer circumferential surface of the roller sleeve rolls against the return section of the connecting rope 14. The torsion spring is pre-torsed during assembly, causing the rocker arm to continuously tend to rotate towards the rope side. The roller sleeve thus applies a constant preload to the return section, which is determined by the effective length of the rocker arm and the stiffness of the torsion spring. When the connecting rope 14 experiences slight elongation due to creep or load changes, the rocker arm automatically swings inward under the drive of the torsion spring, absorbing excess rope length in real time to ensure that the rope lengths at both fixed points are equal. Conversely, when the connecting rope 14 contracts due to a decrease in temperature or load, the rocker arm swings back in the opposite direction, releasing the preload and preventing excessive rope tension. The roller sleeve and the connecting rope 14 are in pure rolling contact, which ensures constant clamping force and eliminates sliding wear, making the rope length adjustment process smooth and noiseless. As a result, the linkage mechanism can achieve self-balancing and self-adjustment within the closed cavity, significantly extending the life of the connecting rope 14 and improving the motion synchronization accuracy.

[0061] In some embodiments, the drive mechanism includes a drive wheel 1, a pulley 8, and a synchronous belt 3 surrounding both. The drive mechanism employs a closed belt drive. Both the drive wheel 1 and the pulley 8 are arranged within the cavity between the middle boom 12 and the outer boom 13, with their rotation axes parallel to each other and their relative positions fixed. The synchronous belt 3 is a closed loop belt with teeth on its inner circumference, its teeth meshing with the outer teeth of the drive wheel 1 and the pulley 8 to form a slip-free meshing transmission. The inner teeth of the synchronous belt 3 maintain meshing with the wheel teeth throughout the entire wrap angle region, preventing slippage even under impact loads or sudden changes in direction, ensuring the synchronicity and positioning accuracy of the lifting movement. The shaft of the drive wheel 1 is rotatably supported on the side wall of the outer boom 13 via a bearing assembly. An end cap is provided on the outer side of the bearing housing to seal the grease and block external impurities. The outer end of the drive wheel 1 can be connected to an external motor or a handle 2; the drive wheel 1 rotates when torque is input.

[0062] The shaft of pulley 8 is fixedly connected to the outer boom 13. Specifically, the hub of pulley 8 is interference-fitted with a short shaft, one end of which is fixed in the reinforcing rib seat of the outer boom 13 and equipped with a lock nut to prevent axial movement. Since pulley 8 is stationary relative to the outer boom 13, when the synchronous belt 3 is pulled by the drive wheel 1, pulley 8 directly transmits the tension of the synchronous belt 3 to the outer boom 13, giving the outer boom 13 a thrust for linear lifting and lowering.

[0063] During operation, the drive wheel 1 rotates under external power, and the synchronous belt 3 forms a closed-loop meshing motion between the drive wheel 1 and the pulley 8. Since the shaft of the pulley 8 is fixed to the outer boom 13, the tension of the straight section of the synchronous belt 3 is applied to the outer boom 13 through the shaft of the pulley 8, pushing the outer boom 13 to rise and fall along the axis of the middle boom 12. The synchronous belt 3 itself has a certain degree of flexibility, which can absorb minor installation errors and impact loads, reduce the impact on the bearings of the drive wheel 1, and extend the service life of the mechanism. By converting the rotational input into belt tension output, the drive mechanism can achieve linear drive without additional gears, racks, pinions, or lead screws. The structure is simple and compact. During maintenance, the synchronous belt 3 can be observed or replaced by opening the side plate of the outer boom 13, which significantly improves assembly and maintenance efficiency.

[0064] In a preferred embodiment, after the synchronous belt 3 engages with the drive wheel 1 and pulley 8, a tensioning wheel 4 abuts against the outer or inner side of the straight section of its closed loop belt. The tensioning wheel 4 is used to maintain the tension of the synchronous belt 3 in real time, preventing the belt from loosening due to temperature changes, running wear, or load impact, which could lead to skipped teeth or abnormal noise. The tensioning wheel 4 consists of a hub, a bearing, an eccentric seat, and an elastic pressing element. The outer circumference of the hub is machined with grooves corresponding to the tooth shape of the synchronous belt 3, so that the tensioning wheel 4 and the belt maintain tooth meshing rather than sliding friction. The bearing is embedded in the inner hole of the hub and supported by a small-diameter short shaft. The root of the short shaft is inserted into the eccentric seat, and the eccentric seat is then fixed to the reinforcing rib of the outer arm frame 13. By rotating the eccentric seat, the radial position of the short shaft relative to the synchronous belt 3 can be adjusted, thereby changing the pressing amount and realizing stepless adjustment of the tension. The elastic pressure element can be a helical spring or a torsion spring, with one end abutting against the eccentric seat and the other end abutting against the inner wall of the outer boom 13, so that the tensioning wheel 4 applies a constant elastic pressure to the synchronous belt 3 during operation and automatically compensates for the slight elongation of the belt.

[0065] The tension pulley 4 can be arranged flexibly. It can be placed inside the synchronous belt 3 to directly press against the belt back, increasing the wrap angle of the meshing section between the belt teeth and the drive wheel 1 and pulley 8, thereby improving the transmission capacity. Alternatively, it can be placed outside the synchronous belt 3 to pull the belt back outward, forming external tension along the length of the belt. The tension pulley 4 can be placed close to the drive wheel 1 to form pre-tension before the belt enters the drive wheel 1, reducing the impact on the root of the drive wheel 1 teeth. It can also be placed close to the pulley 8 to maintain the tension of the back section after the belt leaves the pulley 8, preventing slack side vibration at the end of the pulley 8. Regardless of whether it uses internal pressing or external pulling, the tension pulley 4 is independent of the plane connecting the drive wheel 1 and the pulley 8. Through the cooperation of the eccentric seat and the elastic pressing element, it maintains rolling contact with the synchronous belt 3, providing continuous tension without introducing additional sliding resistance. At the same time, the adjustable structure of the tension pulley 4 eliminates the need for precise cutting of the synchronous belt 3 during assembly, reducing assembly difficulty and improving the adaptability and maintenance convenience of the drive mechanism.

[0066] In some embodiments, the drive mechanism is equipped with five sets of gears and racks on the basis of belt drive to further amplify the output force and improve the positioning rigidity, so that the lifting guide length is located within the overlapping section, thereby further improving the overall rigidity and running stability.

[0067] The first gear 9 is coaxially fixed to the pulley 8, meaning that the first gear 9 and the pulley 8 share the same short shaft and are fixed to the hub of the pulley 8 via a flat key or spline, rotating synchronously with the pulley 8. The external teeth of the first gear 9 mesh with the external teeth of the second gear 7. The shaft of the second gear 7 is supported in the reinforcing rib seat of the outer boom 13, and the shaft end is axially locked with an elastic retaining ring, so that the second gear 7 can only rotate around a fixed axis and cannot produce axial movement. The third gear 6 meshes with the external teeth of the second gear 7. The center distance between their shafts is ensured by two pairs of bearing seat holes on the outer boom 13. The shaft of the third gear 6 is also fixed to the outer boom 13, forming a parallel double gear layout. Two racks 5 are arranged parallel to each other in the vertical direction on the outer wall of the middle boom 12. Specifically, the back of the rack 5 may be provided with a positioning boss, which is embedded in the longitudinal groove of the middle boom 12 and tightened with bolts, so that the rack 5 remains fixed throughout the lifting process. There is a gap between the two racks 5, and the outer teeth of the second gear 7 and the third gear 6 are respectively embedded in the tooth grooves of the corresponding racks 5 to form a double-point meshing.

[0068] During operation, external power is transmitted to pulley 8 via drive wheel 1 and synchronous belt 3. Pulley 8 rotates coaxially with first gear 9. First gear 9 drives second gear 7, which in turn drives third gear 6. While the two gears rotate on a fixed axis, their teeth generate tangential thrust on rack 5. Since rack 5 is fixed to the middle boom 12, according to the principle of action and reaction, the reaction thrust on the gear shaft is directly transmitted to the outer boom 13, pushing the outer boom 13 to rise and fall along the axis of the middle boom 12. The meshing of gears and rack 5 on both sides converts the driving torque into double-sided thrust. That is, second gear 7 and third gear 6 mesh simultaneously on the left and right racks 5, making the forces on both sides of the outer boom 13 symmetrical and effectively suppressing off-center load. The meshing surfaces are in line contact, with high load-bearing capacity and small meshing clearance. Even under impact loads or frequent reversing conditions, creeping and retraction can be avoided, ensuring the synchronicity and positioning accuracy of the lifting movement.

[0069] With the adoption of rack and pinion drive, the load-bearing capacity is improved, making it suitable for heavy-duty working conditions; the continuous rack and pinion guide increases the lateral stiffness of the boom, thereby reducing the platform sway and improving operating comfort; at the same time, the rack and pinion material has high hardness and long fatigue life, and with the dual redundant braking, its reliability is better than that of traditional hydraulic or ball screw solutions, significantly extending the service life of the entire machine.

[0070] In a preferred embodiment, the second gear 7 and / or the third gear 6 are double-plate backlash-eliminating gears. The double-plate backlash-eliminating gear consists of two gear bodies and a wave spring sandwiched between them. The wave spring is used to automatically eliminate the backlash of the gear and rack 5 and maintain non-impact meshing within the set range of center distance variation.

[0071] In some embodiments, the inner boom 11 has an axially extending chamber for accommodating the drive cylinder 17 and providing it with telescopic guidance space. The cylinder body of the drive cylinder 17 is hinged to the base via a pin, and the pin seat is welded to the upper surface of the base. Preferably, a copper alloy bushing is provided inside the pin seat, allowing the cylinder body to swing freely within a small angle range to compensate for manufacturing and installation errors. The piston rod extends upward and is hinged to the lifting lug at the top of the outer boom 13 via a ball joint or clevis bearing. The lifting lug is integrally welded to or bolted to the top plate of the outer boom 13, forming an upward force transmission path. An annular gap is left between the cylinder body exterior and the inner wall of the chamber. Wear-resistant strips or ball bushings can be installed in the gap to prevent lateral swaying of the cylinder body during lifting and to avoid direct metal-to-metal contact that could cause abnormal noise. At the same time, a dustproof sealing cover is provided at the upper end of the chamber. The sealing cover has a circular hole in the center for the piston rod to pass through, and a dustproof ring is embedded in the hole to prevent dust from entering the chamber and extend the life of the seals of the drive cylinder 17.

[0072] During operation, when the drive mechanism pushes the outer boom 13 upward, the top of the outer boom 13 applies tension to the piston rod through a ball joint. The drive cylinder 17 then extends, converting hydraulic or pneumatic energy within the cylinder into mechanical thrust. This thrust, along with the synchronous belt 3 and gear system of the drive mechanism, shares the load, achieving a combined electric and hydraulic or pneumatic drive. When the drive mechanism reverses or suddenly loses power, the drive cylinder 17 can control the return oil or exhaust speed through a throttle valve or balance valve, allowing the outer boom 13 to descend smoothly and preventing excessive speed descent due to gravity.

[0073] Since the cylinder body of the drive cylinder 17 is hinged to the stationary base and the piston rod is hinged to the moving outer boom 13, the cylinder body itself is located in the cavity of the inner boom 11 and extends and retracts synchronously with the lifting and lowering of the outer boom 13. This makes full use of the idle space of the inner boom 11, making the overall shape of the machine simple, without occupying additional external space, and without interfering with the timing belt 3, gears, and racks 5. The extension and retraction stroke of the drive cylinder 17 corresponds to the lifting and lowering stroke of the outer boom 13, forming a built-in power assist and holding unit.

[0074] In some embodiments, the middle boom 12 is fixed with an upper stop block above and a lower stop block below the rack 5, respectively. Both stops are bolted to the middle boom 12 to form rigid stops. The lower edge of the upper stop block is in contact with the top surface of the rack 5 or has a gap, and the upper edge of the lower stop block is in contact with the bottom surface of the rack 5 or has a gap. The outer boom 13 is welded or bolted with an upper limit block and a lower limit block at corresponding positions. Both limit blocks extend horizontally toward the side facing the middle boom 12, and the extended ends are machined with contact surfaces that match the contours of the stops. Preferably, wear-resistant copper pads are embedded to absorb impact energy and reduce noise. When the upper limit block rises with the outer boom 13 and abuts against the upper stop block, the upward movement of the outer boom 13 is cut off, and the middle boom 12 and the outer boom 13 reach the highest limit position simultaneously; when the lower limit block falls with the outer boom 13 and abuts against the lower stop block, the bottom surfaces of the middle boom 12 and the outer boom 13 simultaneously sit on the base, forming the lowest limit position, thus achieving dual protection of the upper and lower ends through purely mechanical hard limit.

[0075] In the same or additional embodiments, the minimum stroke of the drive cylinder 17 corresponds to the lowest limit position of the boom 13, and the maximum stroke of the drive cylinder 17 corresponds to the highest limit position of the boom 13. This correspondence is achieved through mechanical or hydraulic limiting devices inside the cylinder or on the pipeline. For example, a buffer boss is provided at the end of the piston rod, and a buffer cavity is provided inside the cylinder head. When the piston moves to the end, the boss enters the buffer cavity, forming end deceleration and hard stop. Simultaneously, the balance valve or stroke valve automatically cuts off the oil or air supply when the piston approaches its limit position, ensuring that the end point of the cylinder extension / retraction coincides with the mechanical limit end point of the boom 13. Thus, the entire extension / retraction stroke of the drive cylinder 17 matches the lifting / lowering stroke of the boom 13, forming both electrical and mechanical limits. During normal operation, the end point is controlled by the drive cylinder 17. In extreme cases, the impact is absorbed by the hard contact between the upper limit block and the upper stop block, and the lower limit block and the lower stop block, preventing the piston of the drive cylinder 17 from continuing to move and preventing damage to the seals due to over-stroke.

[0076] This structure integrates the mechanical stop, limit block, and the end point of the drive cylinder 17's own stroke on the same lifting path, achieving high-precision protection of the upper and lower ends without the need for additional sensors, thus improving the reliability and safety of the device.

[0077] In some embodiments, the rim of the second gear 7 or the third gear 6 has a radial groove, and a centrifugal pawl is hinged in the radial groove. The root of the centrifugal pawl is connected to the rim of the gear via a pin. A torsion spring is sleeved on the pin, with one end of the torsion spring abutting against the rim and the other end abutting against the inner side of the centrifugal pawl, so that the centrifugal pawl remains in a retracted state when at low speed or at rest. When the second gear 7 or the third gear 6 suddenly decelerates or stops, the centrifugal pawl overcomes the torsion spring force and is thrown outward under the action of inertial centrifugal force. Its wedge-shaped front end engages with the corresponding teeth of the rack 5, forming a mechanical backstop. The size matching between the centrifugal pawl and the teeth of the rack 5 is one-way locking, that is, the centrifugal pawl is allowed to slide over the tooth tip when the gear rotates normally, and the pawl is locked when the gear stops or reverses, thereby preventing the outer boom 13 from sliding down under the action of gravity. The centrifugal pawl is integrated inside the gear rim, without occupying additional cavity space or requiring external control signals. It relies on pure mechanical inertia to form a dual-redundant braking system with the electromagnetic power failure brake. That is, when the electrical side brake fails, the centrifugal pawl can still bear the load independently and provide a safe lock.

[0078] In a preferred embodiment, the shaft of pulley 8 or first gear 9 is connected to the rotor of the electromagnetic power failure brake. For example, the shaft of pulley 8 or first gear 9 extends outward and forms a key connection with the rotor of the electromagnetic power failure brake. Friction plates are embedded in the outer circumference of the rotor hub. The stator of the electromagnetic power failure brake is fixedly connected to the outer boom 13. The stator coil of the electromagnetic power failure brake is connected to the power supply. For example, the stator of the electromagnetic power failure brake is fixed to the inner wall of the outer boom 13 by a flange. A spring is fitted on the outer edge of the stator core. One end of the spring abuts against the bottom of the stator boom, and the other end pushes the armature. The stator coil is connected to the main power supply of the equipment via a lead wire, forming a control logic of power-off braking and power-on release.

[0079] At the moment of power failure, the stator coils lose magnetism, and the pre-compressed annular spring pushes the armature against the rotor end face. The friction plates simultaneously engage with the armature and stator friction surfaces, generating axial clamping force that instantly brakes the rotor. This locks the pulley 8 or the first gear 9, which is coaxial with the rotor, preventing the synchronous belt 3 from slipping backward, thus achieving power failure self-locking. Upon power restoration, the stator coils generate electromagnetic attraction, which overcomes the spring force to pull the armature back, releasing the friction plates. The rotor can then rotate freely with the shaft, restoring the lifting function. Because the electromagnetic power failure brake is integrated into the extended shaft section of the pulley 8 or the first gear 9, it does not occupy additional axial length of the cavity, and the braking torque acts directly on the upstream drive, enabling rapid locking on the shortest possible transmission chain.

[0080] The two locking structures described above can be used simultaneously or individually. When both are used simultaneously, they complement each other at the upstream drive end and the downstream actuator end, improving the safety and reliability of the lifting device in the event of power failure, belt breakage, or unexpected gear reversal.

[0081] In a preferred embodiment, the annular space between the outer wall of the middle boom 12 and the inner wall of the outer boom 13 is directly divided into a first cavity and a second cavity. No physical partition is needed between them; the two cavities can be naturally enclosed by the wall of the outer boom 13 to form a functionally independent channel. The first cavity is located on the front of the middle boom 12 and the outer boom 13, formed by the front wall of the outer boom 13 and the corresponding outer wall of the middle boom 12, creating a vertically connected spatial channel. The drive wheel 1, pulley 8, and synchronous belt 3 of the drive mechanism are all arranged within this channel. The shaft of the drive wheel 1 is directly fixed to the front wall of the outer boom 13 via a bearing seat. The short shaft of the pulley 8 is also interference-fitted with the reinforcing rib seat of the front wall of the outer boom 13 and equipped with a locking nut. Sufficient clearance is maintained between the front and rear of the synchronous belt 3 and the inner wall of the outer boom 13 and the outer wall of the middle boom 12 to avoid friction during operation. Here, "front" refers to the side facing the handle 2 or the drive motor, facilitating operation and maintenance. The second cavity is located on the left and right sides of the middle boom 12 and the outer boom 13, and is formed by the left and right walls of the outer boom 13 and the corresponding outer walls of the middle boom 12, forming a symmetrical spatial channel. Two sets of linkage mechanisms are respectively arranged in the second cavity on both sides. The short shaft of the pulley 10 is directly fixed in the grooves on the left and right outer walls of the middle boom 12. The grooves are reinforced with ribs on both sides to withstand the bidirectional tension of the connecting rope 14 without bending deformation. The two ends of the connecting rope 14 are respectively fixed to the rope end fixing seats on the left and right inner walls of the outer boom 13 and the corresponding fixing seats on the left and right outer walls of the middle boom 12. The rope path and the synchronous belt 3 in the first cavity are independent of each other and do not interfere with each other.

[0082] In some embodiments, front and rear limiting components and left and right limiting components are provided in the gap between the cavity, the outer wall of the inner boom 11 and the inner wall of the middle boom 12, in order to constrain the lateral and longitudinal displacement of each boom and ensure that the lifting process is stable and without deviation.

[0083] The front and rear limiting components are set within the cavity and gap. Specifically, longitudinal protrusions are machined on the front and rear sides of the outer wall of the middle boom 12, and wear-resistant sliding strips are bolted to the corresponding positions on the inner wall of the outer boom 13. The protrusions and sliding strips slide together to limit the front and rear displacement of the middle boom 12 relative to the outer boom 13. Similarly, wear-resistant sliding strips are bolted to the front and rear sides of the outer wall of the inner boom 11, and longitudinal protrusions are machined on the corresponding positions on the inner wall of the middle boom 12. The protrusions and sliding strips slide together to limit the front and rear displacement of the middle boom 12 relative to the inner boom 11. The front and rear limiting components can also adopt a roller 16 and guide rail structure. In this case, the roller 16 is located between the two racks 5, which not only limits the front and rear displacement but also provides lateral limiting.

[0084] The left and right limiting components employ a symmetrically arranged roller 16 and guide rail structure. Specifically, within the cavity, the guide rail is fixed to the outer wall of the middle boom 12, and the roller 16 bracket is fixed to the inner wall of the outer boom 13. The roller 16 clamps the guide rail flange, limiting the left and right displacement of the outer boom 13 relative to the middle boom 12. Within the gap, the guide rail is fixed to the outer wall of the inner boom 11, and the roller 16 bracket is fixed to the inner wall of the middle boom 12. The roller 16 clamps the guide rail flange, limiting the left and right displacement of the middle boom 12 relative to the inner boom 11. The left and right limiting components can also employ a sliding engagement of a convex strip and a sliding bar.

[0085] The front and rear limit components and the left and right limit components are arranged in segments and continuously within the cavity and gap. The guide length covers the entire lifting stroke, so that the inner boom 11, middle boom 12 and outer boom 13 maintain the designed coaxiality at any position, avoiding lateral swaying or twisting and jamming, and ensuring that the lifting process is stable and without deviation.

[0086] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0087] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lifting device, characterized in that, include: An inner boom (11) is provided with a base at its lower end; The middle boom (12) is coaxially sleeved on the outer periphery of the inner boom (11), and the middle boom (12) can be raised and lowered along the axial direction of the inner boom (11); The outer boom (13) is coaxially sleeved on the outer periphery of the middle boom (12). A cavity is provided between the inner wall of the outer boom (13) and the outer wall of the middle boom (12). The outer boom (13) can be raised and lowered along the axial direction of the middle boom (12). A drive mechanism is located inside the cavity, and the drive mechanism is used to drive the outer boom (13) to lift. The linkage mechanism is connected to the outer boom (13) at one end and the middle boom (12) at the other end. The linkage mechanism is used to drive the middle boom (12) to lift synchronously when the outer boom (13) is lifted and lowered, and the lifting speed of the outer boom (13) is greater than the lifting speed of the middle boom (12).

2. The lifting device according to claim 1, characterized in that, The linkage mechanism includes: A pulley (10) is provided on the middle boom (12), and the pulley (10) is located inside the cavity; The connecting rope (14) is wrapped around the pulley (10) in the middle and its two ends are fixed to the inner wall of the outer boom (13) and the outer wall of the middle boom (12), respectively.

3. The lifting device according to claim 2, characterized in that, The linkage mechanism shall be no less than two sets; at least one set of pulleys (10) shall be located at the lower end of the middle boom (12), and at least another set of pulleys (10) shall be located at the upper end of the middle boom (12).

4. The lifting device according to claim 1, characterized in that, The drive mechanism includes a drive wheel (1), a pulley (8), and a timing belt (3) surrounding both; the shaft of the drive wheel (1) is rotatably supported on the outer boom (13), and the shaft of the pulley (8) is fixedly connected to the outer boom (13).

5. The lifting device according to claim 4, characterized in that, The drive mechanism also includes: The first gear (9) is coaxially fixed to the pulley (8); The second gear (7) meshes with the first gear (9), and the shaft of the second gear (7) is fixed to the outer boom (13). The third gear (6) meshes with the second gear (7), and the shaft of the third gear (6) is fixed to the outer boom (13). Two racks (5) are arranged vertically at intervals on the middle boom (12), and the second gear (7) and the third gear (6) respectively mesh with the two racks (5).

6. The lifting device according to claim 5, characterized in that, The middle boom (12) is fixed with an upper stop block and a lower stop block above and below the rack (5), respectively; the outer boom (13) is provided with an upper limit block and a lower limit block. When the upper limit block abuts against the upper stop block, the middle boom (12) and the outer boom (13) reach the highest limit position simultaneously. When the lower limit block abuts against the lower stop block, the bottom surfaces of the middle boom (12) and the outer boom (13) sit on the base at the same time, forming the lowest limit position.

7. The lifting device according to claim 6, characterized in that, The inner boom (11) has a chamber inside, in which a drive cylinder (17) is installed. The cylinder body end of the drive cylinder (17) is hinged to the base, and the piston rod end extends upward and is hinged to the top of the outer boom (13). The drive cylinder (17) extends and retracts synchronously with the lifting and lowering of the outer boom (13).

8. The lifting device according to claim 7, characterized in that, The minimum stroke of the drive cylinder (17) corresponds to the lowest limit position of the outer boom (13), and the maximum stroke of the drive cylinder (17) corresponds to the highest limit position of the outer boom (13).

9. The lifting device according to claim 5, characterized in that, A centrifugal pawl is hinged to the rim of the second gear (7) or the third gear (6). When the second gear (7) or the third gear (6) stops rotating, the centrifugal pawl is thrown out by inertia and gets into the corresponding tooth of the rack (5).

10. The lifting device according to claim 1, characterized in that, The cavity, the gap between the outer wall of the inner boom (11) and the inner wall of the middle boom (12) are all equipped with front and rear limiting components and left and right limiting components to constrain the lateral and longitudinal displacement of each boom.

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