Lifting machine and its control method

Abstract

A lifting machine and its control method are disclosed. The lifting machine includes a main body, support legs, a ball screw assembly, a power unit, a braking device, and a self-locking device. The self-locking device includes: a gear plate surrounding and fixedly connected to the ball screw; a toothed pawl corresponding to the gear plate and rotatably connected to the side of the main body; a first elastic element and an electric actuator providing force to the toothed pawl. The control method includes: upon receiving a lifting command, controlling the braking device to disengage from the braking state and controlling the toothed pawl of the self-locking device to switch to a disengaged state; then controlling the power unit to actuate and drive the support legs and the main body to move relative to each other; upon receiving a stop command, controlling the braking device to engage from the braking state and controlling the toothed pawl of the self-locking device to switch to an engaged state. This lifting machine uses the dual action of the braking device and the self-locking device to maintain the lifting machine in the lifted state, and the self-locking device acts directly on the ball screw, resulting in higher reliability.

Description

Technical Field

[0001] This invention relates to the field of lifting machines based on ball screw pairs, specifically a lifting machine and its control method. Background Technology

[0002] Some existing lifting machines include a main body for connecting the object to be lifted, support legs sleeved with the main body and movable vertically relative to the main body, a ball screw assembly connecting the main body and the support legs, a power unit for driving the screw to rotate, and a braking device disposed on the power unit. The ball screw assembly includes a ball screw and a nut, wherein the nut is fixedly connected to the support legs, and the screw is fixedly connected to the main body through a support seat. The ball screw assembly converts the rotational motion of the screw into the linear motion of the nut. The linear motion of the nut drives the support legs to move vertically relative to the main body, thereby achieving the lifting function. After lifting, the power unit stops working, and the braking device generates braking force on the shaft of the power unit to hold the lifting machine in the lifted state.

[0003] Ball screw assemblies, due to their low coefficient of rolling friction, offer high transmission efficiency. However, a critical weakness is their lack of self-locking capability compared to trapezoidal screw assemblies. This results in the following technical drawbacks for lifting machines using ball screw assemblies: 1. Increased risk of the lifted object falling. In the lifted state, overload, brake failure, or a failure in the transmission chain between the power unit and the screw assembly can cause the screw to reverse, leading to the object falling. 2. Limited application. When used in vehicles, the support legs are retracted under no-load conditions, maintained by the brakes on the power unit. Failure of the brakes or the transmission chain between the power unit and the screw assembly can cause the support legs to slide under their own weight, posing a safety hazard to vehicles.

[0004] In view of this, the present invention proposes an improvement. Summary of the Invention

[0005] The main objective of this invention is to provide a lifting machine that solves the problem that the lifted object will fall when the existing lifting machine using ball screw pairs is in the lifting state if overload, braking device failure, or transmission chain failure occurs, thereby improving the reliability of the lifting machine.

[0006] A further objective of this invention is to address the problem that when this type of lifting machine is used in vehicles, the support legs may slide down if the braking device or transmission chain fails when the machine is unloaded, thereby improving the safety of this type of lifting machine when used in vehicles.

[0007] To achieve the above-mentioned main objectives, the present invention provides a lifting machine comprising:

[0008] The main body for connecting the object being topped includes a cylindrical structure;

[0009] Support legs that are sleeved with the cylindrical structure of the main body and can move up and down relative to the main body;

[0010] A ball screw assembly, the ball screw assembly including a screw and a nut, the nut being fixedly connected to the support leg, the screw including a support seat, the support seat being fixedly connected to the main body;

[0011] A power device for driving the lead screw to rotate;

[0012] Braking device provided in the power unit; and

[0013] A self-locking device, the self-locking device comprising:

[0014] A gear disc that surrounds the lead screw and is fixedly connected to the lead screw;

[0015] The toothed pawl, which corresponds to the toothed disc and is rotatably connected to the side of the main body, includes an engaged state and a disengaged state. In the engaged state, the toothed pawl is located inside the tooth groove on the toothed disc, and in the disengaged state, the toothed pawl is located outside the tooth groove on the toothed disc.

[0016] A first elastic element provides a force to the pawl to cause it to engage; and

[0017] An electric actuator that provides force to the pawl to cause the pawl to enter a disengaged state.

[0018] The aforementioned lifting machine includes both a braking device and a self-locking device, allowing it to remain in the lifted state through the combined action of the braking and self-locking devices, thus improving reliability. Specifically, the self-locking device includes a geared disc surrounding and fixedly connected to the lead screw; a pawl corresponding to the geared disc and rotatably connected to the side of the main body, the pawl having an engaged state and a disengaged state. In the engaged state, the pawl is within a groove on the geared disc; in the disengaged state, the pawl is outside the groove on the geared disc; a first elastic element provides force to the pawl to engage it; and an electric actuator provides force to the pawl to disengage it. This allows the self-locking device to act directly on the lead screw, ensuring that the lifting machine remains in the lifted state even when the braking device and the transmission chain between the power device and the lead screw fail.

[0019] Optionally, the electric actuator includes an energized state and an de-energized state. In the energized state, the toothed pawl is in a disengaged state, and in the de-energized state, the toothed pawl is in a engaged state.

[0020] Optionally, the self-locking device further includes a manual actuator, the manual actuator comprising:

[0021] A crank handle is located on the outside of the main body and is fixedly connected to the rotating shaft of the toothed claw;

[0022] A plunger disposed on the crank handle, the plunger being movable in a direction parallel to the rotation center line of the toothed pawl; and

[0023] Corresponding to the separated state of the toothed claw and the plunger hole provided on the side of the main body.

[0024] Optionally, the crank handle is further provided with a locking mechanism for locking the position of the plunger.

[0025] To achieve the aforementioned further objective, the lifting machine further includes a fall prevention device, which includes:

[0026] A friction washer surrounding the lead screw and fixedly connected to the upper end of the support base of the lead screw; and

[0027] A damping sleeve surrounds the lead screw and its end is in frictional engagement with the upper end of the friction washer; the damping sleeve is fixedly connected to the lead screw.

[0028] With the addition of the aforementioned anti-fall device, when the lead screw rotates due to the gravity of the support leg, the damping sleeve will rub against the friction washer, generating a reverse resistance torque to prevent the lead screw from rotating, thus preventing the support leg from falling due to gravity. The specific structure of the anti-fall device allows it to act directly on the lead screw, unaffected by transmission chain failures between the lead screw and its power unit. Furthermore, it is entirely implemented by a mechanical structure, unaffected by power outages, thus possessing good reliability. It also boasts advantages such as simple structure and low cost.

[0029] Optionally, the anti-fall device further includes a second elastic element that surrounds the lead screw and acts downward on the lead screw.

[0030] Optionally, the second elastic element includes:

[0031] Spring washers; and

[0032] A gasket, the gasket including a central hole and a positioning groove surrounding the central hole, the spring washer being fixed to the positioning groove, and the central hole being slidably engaged with the optical axis of the lead screw.

[0033] Optionally, the size of the friction washer is configured as: (D+d) / 2≥FS*R / (2π*FS*μ), where D is the outer diameter of the friction washer, d is the inner diameter of the friction washer, μ is the friction coefficient between the friction washer and the damping sleeve, FS is the weight of the support leg, and R is the lead of the lead screw pair.

[0034] Optionally, the power unit includes a reducer and a motor fixedly connected to the side of the main body;

[0035] The main body is rotatably connected to the top of the lead screw. The drive shaft is perpendicular to the lead screw. The drive shaft includes a power input end, a power output end, and a first bevel gear. The power input end is connected to the power output shaft of the reducer, and the power output end extends out of the main body.

[0036] The lead screw is fixedly connected to a second bevel gear, which meshes with the first bevel gear.

[0037] One control method for the aforementioned lifting machine includes the following steps:

[0038] Upon receiving the lifting command, the braking device is disengaged from the braking state, and the power device and electric actuator are linked to switch the pawl of the self-locking device to the disengaged state.

[0039] When the pawl enters the disengaged state, the power device is controlled to move the support leg and the main body relative to each other.

[0040] Upon receiving a stop command or feedback indicating that the travel has been completed, the braking device is controlled to enter the braking state, and the electric actuator is controlled to release the force on the pawl, so that the pawl of the self-locking device switches to the engaged state.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] This lifting machine includes both a braking device and a self-locking device, allowing it to remain in the lifted state through the combined action of the braking and self-locking devices, thus improving reliability. Specifically, the self-locking device includes a geared disc surrounding and fixedly connected to the lead screw; a pawl corresponding to the geared disc and rotatably connected to the side of the main body, the pawl having an engaged state and a disengaged state. In the engaged state, the pawl is within a groove on the geared disc; in the disengaged state, the pawl is outside the groove on the geared disc; a first elastic element provides force to the pawl to engage it; and an electric actuator provides force to the pawl to disengage it. This allows the self-locking device to act directly on the lead screw, ensuring that the lifting machine remains in the lifted state even when the braking device and the transmission chain between the power unit and the lead screw fail.

[0043] With the addition of the aforementioned anti-fall device, when the lead screw rotates due to the gravity of the support leg, the damping sleeve will rub against the friction washer, generating a reverse resistance torque to prevent the lead screw from rotating, thus preventing the support leg from falling due to gravity. The specific structure of the anti-fall device allows it to act directly on the lead screw, unaffected by transmission chain failures between the lead screw and its power unit. Furthermore, it is entirely implemented by a mechanical structure, unaffected by power outages, thus possessing good reliability. It also boasts advantages such as simple structure and low cost. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the external structure of a lifting machine according to one embodiment;

[0045] Figure 2 This is a schematic diagram of the side panel that connects to the vehicle.

[0046] Figure 3 This is a schematic diagram of the transmission chain between the lead screw and the first motor;

[0047] Figure 4 A schematic diagram showing the combination of its self-locking device, main body, and lead screw pair;

[0048] Figure 5 A schematic diagram of the toothed claw of the self-locking device;

[0049] Figure 6 A schematic diagram of the toothed disc of the self-locking device;

[0050] Figure 7 This is a schematic diagram showing the position of the manual actuator on the main body.

[0051] Figure 8 This is a schematic diagram of the manual actuator.

[0052] Figure 9 for Figure 8 Decomposition state diagram;

[0053] Figure 10 A schematic diagram of the combination of the anti-fall device and the lead screw assembly;

[0054] Figure 11 A schematic diagram of the damping sleeve for the anti-fall device;

[0055] Figure 12 A schematic diagram of the friction washer for the anti-fall device;

[0056] Figure 13 This is a schematic diagram of the structure of the washer sleeve for a spring washer. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0058] Unless otherwise specified, the terms "first," "second," etc., in this application are used to distinguish different components with the same name and do not imply any degree of importance or sequential relationship.

[0059] Reference Figures 1-10 The lifting machine in this embodiment includes: support leg 10, main body 20, power unit 30, braking device 40, ball screw pair 50, self-locking device 60, and anti-fall device 70.

[0060] The main body 20 includes a cylindrical structure for accommodating the support leg 10 and for fixing the electric lift to the object being lifted, such as a vehicle. In this embodiment, the main body 20 specifically adopts a quadrangular prism cylindrical structure, with one side of the quadrangular prism forming a mounting surface. This side is provided with a connecting hole. During installation, this side is aligned with the mounting surface on the vehicle, and a bolt 21 is passed through the connecting hole and locked to secure the lift to the vehicle.

[0061] The support leg 10 is sleeved with the cylindrical structure of the main body 20, and can move up and down relative to the main body 20.

[0062] The ball screw assembly 50 includes a ball screw 52 and a nut 51, wherein the nut 51 is fixedly connected to the support leg 10. The ball screw 52 includes a support seat 522, an upper thrust bearing 523 and a lower thrust bearing 521. The support seat 522 is welded to the main body 20. The upper thrust bearing 523 corresponds to the upper end of the support seat 522, and the lower thrust bearing 521 corresponds to the lower end of the support seat 522.

[0063] The power unit 30 includes a reducer 31 and a first motor 32, which are fixedly mounted on one side of the main body 20 to provide power to the lead screw pair 50. In this embodiment, a laterally extending drive shaft 82 is specifically provided at the upper end of the main body 20. The drive shaft 82 is connected to the power output end of the reducer 31, and the drive shaft 82 is connected to the lead screw 52 via a bevel gear pair 81. The bevel gear pair 81 includes a first bevel gear mounted on the drive shaft 82 and a second bevel gear mounted on the lead screw 52. The power output by the first motor 32 is reduced by the reducer 31 and drives the drive shaft 82 to rotate. The rotational motion of the drive shaft 82 is transmitted to the lead screw 52 through the bevel gear pair 81, providing the power to rotate the lead screw 52.

[0064] The reducer 31, the drive shaft 82, and the bevel gear pair 81 together form the transmission chain between the first motor 32 and the lead screw 52.

[0065] When the first motor 32 rotates forward, the support leg 10 moves upward and retracts, detaching from the ground; when the first motor 32 rotates in reverse, the support leg 10 moves downward and contacts the ground to form support, thereby lifting the vehicle upward. Or vice versa.

[0066] The first motor 32 includes a power shaft, which has a head end and a tail end, and the head end is connected to the reducer 31.

[0067] A braking device 40 is located at the tail end of the power shaft of the first motor 32 to brake the first motor 32. Optionally, the braking device 40 is an electromagnetic brake, preferably an electromagnetic brake that: brakes the power shaft of the first motor 32 when power is lost and releases the power shaft of the first motor 32 when power is restored.

[0068] Reference Figures 4-6 The self-locking device 60 includes a toothed disc 61, a toothed pawl 62, a first elastic element, and an electric actuator 63.

[0069] The gear disk 61 includes a first central hole 612 and a plurality of tooth grooves 611 formed around the first central hole 612 on the upper end of the gear disk 61. The first central hole 612 is fixedly connected to the lead screw 52.

[0070] The toothed pawl 62 corresponds to the gear disc 61. The toothed pawl 62 includes a connecting pin 621 and a rotating shaft 622. The toothed pawl 62 is rotatably connected to the side of the main body 20 through the rotating shaft 622. The connecting pin 621 is used to connect the electric actuator 63. The toothed pawl 62 has an engaged state and a disengaged state. In the engaged state, the toothed pawl 62 is located within the tooth groove 611 on the gear disc 61, restricting the reverse rotation of the gear disc 61 and the lead screw 52. In the disengaged state, the toothed pawl 62 is located outside the tooth groove 611 on the gear disc 61, and does not obstruct the rotation of the lead screw 52.

[0071] The first elastic element provides a force to the pawl 62 to engage it. This first elastic element can be a torsion spring, which is fitted onto the pivot 622 of the pawl 62, with its two arms connected to the pawl 62 and the main body 20 respectively, to provide the force. Alternatively, the first elastic element can be a compression spring or a tension spring, with one end connected to the main body 20 and the other end connected to the pawl 62 at a position offset from the pivot 622 to provide the force.

[0072] An electric actuator 63 is used to drive the pawl 62 into the disengaged state. Specifically, the electric actuator 63 is a push rod electromagnet, the body of which is fixed to the side of the lifting machine's main body 20. The push rod of the push rod electromagnet is connected to a pin 621 on the pawl 62. The upward movement of the push rod drives the pawl 62 into the disengaged state. The electric actuator 63 can also be a push rod motor. Preferably, the pawl 62 is in the disengaged state when the electric actuator 63 is energized, and in the engaged state when the electric actuator 63 is de-energized, to achieve better reliability.

[0073] Since this lifting machine includes both a braking device 40 and a self-locking device 60, it can be kept in the lifting state by the dual action of the braking device 40 and the self-locking device 60, thus making it more reliable. The self-locking device 60 includes a gear disk 61 surrounding and fixedly connected to the lead screw 52; a toothed pawl 62 corresponding to the gear disk 61 and rotatably connected to the side of the main body 20, the toothed pawl 62 having an engaged state and a disengaged state, the toothed pawl 62 being in the tooth groove on the gear disk 61 in the engaged state, and the toothed pawl 62 being outside the tooth groove on the gear disk 61 in the disengaged state; a first elastic member providing force to the toothed pawl 62 to cause the toothed pawl 62 to enter the engaged state; and an electric actuator 63 providing force to the toothed pawl 62 to cause the toothed pawl 62 to enter the disengaged state, so that the self-locking device 60 can directly act on the lead screw 52, ​​and when the braking device 40 and the transmission chain between the power device 30 and the lead screw 52 all fail, the self-locking device 60 can still keep the lifting machine in the lifting state.

[0074] Reference Figures 7-9Furthermore, the self-locking device 60 also includes a manual actuator 64, which is disposed on the outer side of the main body 20 corresponding to the toothed pawl 62. The manual actuator 64 specifically includes a crank handle 641, a plunger 642, a first plunger hole 643, and a second plunger hole 644. The crank handle 641 is disposed on the outer side of the main body 20 and is fixedly connected to the rotating shaft 622 of the toothed pawl 62. The plunger 642 is disposed on the crank handle 641, and the first plunger hole 643 and the second plunger hole 644 are disposed on the side of the main body 20, corresponding to the plunger 642. The plunger 642 can move along a direction parallel to the rotation center line of the toothed pawl 62. In this embodiment, the crank handle 641 specifically includes a handle 6411 and a crank 6412. The rotating shaft 622 of the toothed pawl 62 is fixedly connected to the crank 6412. The rotating shaft 622 is disposed on the bearing seat 65. The first plunger hole 643 and the second plunger hole 644 are disposed on the outer cover plate 66. The bearing seat 65 and the outer cover plate 66 are disposed opposite to each other, and the bearing seat 65 and the outer cover plate 66 are respectively located on the inner and outer sides of the side of the main body 20. The bearing seat 65 and the outer cover plate 66 are fixed to the side of the main body 20 by screws. Specifically, there are two plunger holes. The second plunger hole 644 corresponds to the disengaged state of the toothed pawl 62, and the first plunger hole 643 corresponds to the engaged state of the toothed pawl 62.

[0075] When the electric actuator 63 fails to start, the self-locking device 60 can be operated by the manual actuator 64. Specifically, rotating the crank 641 clockwise causes the rotating shaft 622 to rotate, which in turn causes the toothed pawl 62 to rotate clockwise. When the toothed pawl 62 is engaged, the plunger 642 aligns with the first plunger hole 643, pushing the plunger 642 into the first plunger hole 643. The first plunger hole 643 and the plunger 642 cooperate to keep the toothed pawl 62 in the engaged state. Similarly, the second plunger hole 644, corresponding to the disengaged state of the toothed pawl 62, is used to cooperate with the plunger 642 to keep the toothed pawl 62 in the disengaged state.

[0076] Furthermore, a locking mechanism is provided on the crank handle 641. This locking mechanism is used to lock the position of the plunger 642, ensuring that after the plunger 642 is inserted into the first plunger hole 643 or the second plunger hole 644, it will not dislodge from the plunger hole due to vibration or accidental impact. Specifically, threads can be provided between the plunger hole and the plunger to lock the plunger in the plunger hole. Alternatively, the plunger can be a spring pin, using the elastic force of the spring pin to lock the plunger in the plunger hole, and applying an outward pulling force to pull the plunger out of the plunger hole.

[0077] When the vehicle is in motion, the support legs 10 of the lifting machine are in the retracted state, which is also a suspended state; this state is also called the unloaded state. In the unloaded state, the braking device 40 is in the braking state, locking the motor's power shaft and thus keeping the support legs 10 in the retracted state. If the braking device 40 fails or the transmission chain between the ball screw 52 and its power unit fails, the braking force will not be applied to the ball screw pair. Since the ball screw pair does not have a self-locking function, under the weight of the support legs 10 themselves, the screw will reverse, causing the support legs 10 to slide down, posing a safety hazard. This can be solved by using the anti-fall device 70.

[0078] Reference Figure 10-13 The anti-fall device 70 includes a friction washer 73 and a damping sleeve 72.

[0079] Friction washer 73 surrounds the lead screw 52 and is fixedly connected to the upper end of the support seat 522 of the lead screw 52. (Refer to...) Figure 12 In this embodiment, the friction washer 73 specifically includes: a second central hole 732 and a plurality of first pin holes 731, all of which are distributed around the second central hole 732. Figure 10 and Figure 12 The second center hole 732 mates with the optical axis of the lead screw 52, ​​and the first pin hole 731 connects with the connecting pin at the upper end of the support base 521. The friction washer 73 can also be fixedly connected to the support base 522 in other ways, such as welding.

[0080] The damping sleeve 72 surrounds the lead screw 52, ​​and its end is in frictional engagement with the upper end of the friction washer 73. The damping sleeve 72 is fixedly connected to the lead screw 52. (Refer to...) Figure 11 In this embodiment, the damping sleeve 72 specifically includes: a base plate 721 having a third central hole 722, and a cylindrical portion 724 extending perpendicularly from the edge of the third central hole 722 to the base plate 721. The cylindrical portion 724 is provided with a second pin hole 723. Figure 10 and Figure 11 The cylindrical portion 724 is sleeved with the lead screw 52, ​​and the second pin hole 723 is connected to the pin connection 71 on the lead screw 52, ​​so that the damping sleeve 72 is fixedly connected to the lead screw 52. The base plate 721 and the friction washer 73 form a friction fit. The damping sleeve 72 can also be fixedly connected to the lead screw 52 in other ways, such as by welding. When welding is used, the damping sleeve 72 may not have the cylindrical portion 724 and the second pin hole 723.

[0081] With the aforementioned anti-fall device 70 installed, when the lead screw 52 rotates due to the gravity of the support leg 10, the damping sleeve 72 will rub against the friction washer 73, thereby generating a reverse resistance torque to prevent the lead screw 52 from rotating, thus preventing the support leg 10 from falling due to gravity. The specific structure of the aforementioned anti-fall device 70 allows it to act directly on the lead screw 52, ​​unaffected by the failure of the transmission chain between the lead screw 52 and its power device 30. Furthermore, it is entirely implemented by a mechanical structure, unaffected by power outages, thus possessing good reliability. It also boasts advantages such as simple structure and low cost.

[0082] The sizes of the friction washer 73 and the damping sleeve 72 can be configured according to the following formula: (D+d) / 2≥FS*R / (2π*FS*μ), where D is the outer diameter of the friction washer, d is the inner diameter of the friction washer, μ is the coefficient of friction between the friction washer and the damping sleeve, FS is the weight of the support leg, and R is the lead of the lead screw pair. In some embodiments, the coefficient of friction μ is in the range of [0.1-0.15], the friction washer 73 is made of steel, and the damping sleeve 72 is made of tin bronze.

[0083] The anti-fall device 70 effectively solves the problem that when a lifting machine using a ball screw pair is used in a vehicle, the support leg 10 will slide down if the brake device 40 or the transmission chain fails when unloaded, thus improving the safety of this type of lifting machine when used in a vehicle.

[0084] During vehicle operation, road surface undulations may cause the friction washer 73 and damping sleeve 72 to temporarily detach, resulting in a slight drop in the support leg 10. Over prolonged driving, this slight drop can accumulate and potentially cause the support leg 10 to contact the ground, leading to an accident. To further address this issue, a second elastic element is added. This element generates downward elastic pressure on the damping sleeve 72, which pre-tightens the friction washer 73 and damping sleeve 72. This counteracts the upward pressure exerted on the damping sleeve 72 by the lead screw 52 during vehicle vibrations, ensuring a seamless connection between the friction washer 73 and damping sleeve 72.

[0085] Reference Figure 10 In this embodiment, the second elastic element includes a spring washer 75. Specifically, the lower thrust bearing 521 includes an upper race 5211 and a lower race 5212. The spring washer 75 is press-fitted with the upper race 5211 of the lower thrust bearing 521 and the lower end of the support seat 522, respectively, to form a downward elastic pressure on the lead screw 52. This elastic pressure is transmitted to the damping sleeve 72 through the lead screw 52, ​​thereby causing the friction washer 73 and the damping sleeve 72 to be pre-tightened.

[0086] Furthermore, the second elastic element also includes a gasket 74, combined with... Figure 10 and Figure 13The bushing 74 includes a fourth central hole 741 and a positioning groove 742 surrounding the fourth central hole 741. The spring washer 75 is fixed to the positioning groove 742, and the fourth central hole 741 is slidably engaged with the optical axis of the lead screw 72. The bushing 74 can provide radial positioning for the spring washer 75, ensuring consistent preload.

[0087] It should be noted that the second elastic element is not necessarily located on the lower side of the support base 522; it can also be located on the upper side of the support base 522. Furthermore, the second elastic element can act directly on the damping sleeve 72 or indirectly on the damping sleeve 72. For example, the second elastic element can also be located on the upper side of the damping sleeve 72, directly generating downward elastic pressure on the damping sleeve 72. Alternatively, the second elastic element can also be located on the upper side of the upper thrust bearing 523, transmitting the downward elastic pressure to the lead screw 52 through the upper thrust bearing 523, and then to the damping sleeve 72 through the lead screw 52.

[0088] The aforementioned lifting machine includes a self-locking device 60. In the lifted state, the braking device 40 and the self-locking device 60 work together to maintain the lifting machine in its lifted state. One control method is as follows:

[0089] Upon receiving the lifting command, the braking device 40 is controlled to disengage from the braking state, and the power device 30 and the electric actuator 63 are controlled to work together to switch the pawl 62 of the self-locking device 60 to the disengaged state. Specifically, the power device 30 first drives the lead screw 52 to move for a certain period of time, so that the friction between the pawl 62 and the toothed disc 61 is released. Then, the electric actuator 63 drives the pawl 62 to move around its rotating shaft 622 and enter the disengaged state.

[0090] When the toothed claw 62 enters the separation state, the power device 30 is controlled to move the support leg 10 and the main body 20 relative to each other. Specifically, a sensor can be installed on one side of the toothed claw 62 to detect whether the toothed claw 62 has entered the separation state.

[0091] Upon receiving a stop command or feedback information indicating that the travel has reached its limit, the braking device 40 is controlled to enter the braking state, and the electric actuator 63 is controlled to release the force on the pawl 62. Under the action of the first elastic element, the pawl 62 enters the engagement state or the waiting engagement state (the waiting engagement state means that the pawl 62 is on the tooth top of the tooth disk 61. In this state, as long as the tooth disk 61 rotates, the pawl 62 will fall into the tooth groove 611 of the tooth disk 61 and enter the engagement state). This allows the braking device 40 and the self-locking device 60 to work together to maintain the lifting state of the lifting machine.

[0092] The present invention has been described in detail above through specific embodiments. These detailed descriptions are only intended to help those skilled in the art understand the content of the present invention and should not be construed as limiting the scope of protection of the present invention. Various modifications and equivalent transformations made by those skilled in the art to the above solutions under the concept of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lifting machine, characterized in that, include: The main body (20) for connecting the top object includes a cylindrical structure; Support legs (10) that are sleeved with the cylindrical structure of the main body and can move up and down relative to the main body; A ball screw assembly (50) includes a screw (52) and a nut (51), the nut being fixedly connected to the support leg, and the screw including a support seat, the support seat being fixedly connected to the main body; A power device (30) for driving the lead screw to rotate; Braking device (40) installed in the power unit; as well as Self-locking device (60), the self-locking device comprising: A toothed disc (61) surrounds the lead screw and is fixedly connected to the lead screw; The toothed claw (62) is rotatably connected to the side of the main body and corresponds to the toothed disc. The toothed claw has an engaged state and a disengaged state. In the engaged state, the toothed claw is located in the tooth groove on the toothed disc, and in the disengaged state, the toothed claw is located outside the tooth groove on the toothed disc. A first elastic element provides a force to the pawl to cause it to engage; and An electric actuator (63) provides force to the pawl to cause the pawl to enter a disengaged state; The lifting machine also includes an anti-fall device (70) to prevent the support leg from sliding down due to gravity. The anti-fall device includes: A friction washer (73) surrounding the lead screw and fixedly connected to the upper end of the support seat of the lead screw; and A damping sleeve (72) surrounds the lead screw and its end is in frictional engagement with the upper end of the friction washer; the damping sleeve is fixedly connected to the lead screw. The self-locking device (60) further includes a manual actuator (64), which includes: A rocker handle (641) is located on the outside of the main body and is fixedly connected to the pivot of the toothed claw; A plunger (642) disposed on the crank handle, the plunger being movable in a direction parallel to the rotation center line of the toothed pawl; and Corresponding to the separated state of the toothed claw and the plunger hole disposed on the side of the main body; The size of the friction washer is configured as follows: (D+d) / 2≥FS*R / (2π*FS*µ)where D is the outer diameter of the friction washer, d is the inner diameter of the friction washer, µ is the friction coefficient between the friction washer and the damping sleeve, FS is the weight of the support leg, and R is the lead of the lead screw pair.

2. The lifting machine according to claim 1, characterized in that, The electric actuator includes an energized state and an de-energized state. In the energized state, the toothed jaws are in a disengaged state, and in the de-energized state, the toothed jaws are in a engaged state.

3. The lifting machine according to claim 1, characterized in that, The crank handle is also provided with a locking mechanism, which is used to lock the position of the plunger.

4. The lifting machine according to claim 1, characterized in that, The anti-fall device further includes a second elastic element that surrounds the lead screw and acts downward on the lead screw.

5. The lifting machine according to claim 4, characterized in that, The second elastic element includes: Spring washer (75); and The sleeve (74) includes a central hole and a positioning groove surrounding the central hole. The spring washer is fixed to the positioning groove, and the central hole is slidably engaged with the optical axis of the lead screw.

6. The lifting machine according to claim 1, characterized in that, The power unit (30) includes a reducer (31) and a motor fixedly connected to the side of the main body; The main body is rotatably connected to the top of the lead screw by a transmission shaft (82). The transmission shaft is perpendicular to the lead screw. The transmission shaft includes a power input end, a power output end and a first bevel gear. The power input end is connected to the power output shaft of the reducer and the power output end extends out of the main body. The lead screw is fixedly connected to a second bevel gear, which meshes with the first bevel gear.

7. A lifting machine control method, characterized in that, The lifting machine is the lifting machine as described in any one of claims 1-6, and the control method includes the following steps: Upon receiving the lifting command, the braking device is disengaged from the braking state, and the power device and electric actuator are linked to switch the pawl of the self-locking device to the disengaged state. When the pawl enters the disengaged state, the power device is controlled to move the support leg and the main body relative to each other. Upon receiving a stop command or feedback information indicating that the travel is complete, the braking device is controlled to enter the braking state, and the electric actuator is controlled to release the force on the pawl, so that the pawl of the self-locking device switches to the engaged state.

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