CN106763594B

CN106763594B - Operation mesa elevating gear

Info

Publication number: CN106763594B
Application number: CN201710176672.1A
Authority: CN
Inventors: 王春爱; 江春霞; 刘庆梅; 徐婷; 申作剑; 辛本强; 胡家宁
Original assignee: Rizhao Polytechnic
Current assignee: Rizhao Polytechnic
Priority date: 2015-02-16
Filing date: 2015-02-16
Publication date: 2020-05-15
Anticipated expiration: 2035-02-16
Also published as: CN106838177A; CN107061654A; CN106838177B; CN106821652A; CN106838176B; CN106838176A; CN104653735B; CN106821652B; CN106821651B; CN106821651A; CN104653735A; CN107061654B; CN106763594A

Abstract

The invention discloses an operation table top lifting device, which belongs to the field of machinery and is characterized in that: comprises a rack, a motor, a gear rack, a shell and a plurality of gears; the rack is meshed with the first gear; the output shaft of the motor is connected with a third gear, and the third gear is meshed with the second gear; the gear rack is hinged with a shaft where the first gear and the second gear are located; the motor is fixedly connected with the gear frame; a fourth gear is arranged below the second gear, is meshed with the second gear and is fixedly connected with a coaxial first star wheel; the gear rack is provided with a fifth gear and a sixth gear which are meshed with each other, and the fifth gear and the sixth gear are fixedly connected with a second star wheel and a third star wheel which are coaxial respectively. Compared with the prior art have the characteristics of power saving, stable performance.

Description

Operation mesa elevating gear

Technical Field

The invention relates to a mechanical device, in particular to a lifting device suitable for a medical operation table top, which is a divisional application of an invention patent application, namely a lifting device (application number: 2015100829442).

Background

The lifting structure is widely applied to various mechanical devices, such as material lifting, auxiliary lifting and the like. At present, the most widely used lifting device is electric lifting, wherein in order to prevent the free descending speed from being too fast to cause larger impact in the descending process, the descending is generally decelerated and descended by adopting a motor-driven descending and friction mode. The former causes power loss during the descending process, and the latter causes failure phenomenon due to the abrasion of the friction piece after long-term use.

Disclosure of Invention

The technical task of the invention is to provide a power-saving and stable-performance operating table top lifting device aiming at the defects of the prior art.

The technical scheme for solving the technical problem is as follows: the utility model provides an operation mesa elevating gear which characterized in that: the gear locking device comprises a rack, a motor, a gear rack, a shell, a plurality of gears and a locking device; the rack is vertically arranged and penetrates through the shell, the rack is meshed with the first gear, the first gear and the second gear form a duplicate gear together, and a shaft of the duplicate gear is arranged on the shell; the output shaft of the motor is connected with a third gear, and the third gear is meshed with the second gear; the gear rack is hinged with a shaft where the first gear and the second gear are located; the motor is fixedly connected with the gear frame; a fourth gear is arranged below the second gear, is meshed with the second gear and is fixedly connected with a coaxial first star wheel; the shaft of the fourth gear and the shaft of the first star wheel are arranged on the shell; the gear rack is provided with a fifth gear and a sixth gear which are meshed with each other, and the fifth gear and the sixth gear are respectively and fixedly connected with a second star wheel and a third star wheel which are coaxial; the three star wheels are positioned on the same vertical plane, and the sum of the maximum radiuses of the second star wheel and the third star wheel is smaller than the sum of the radiuses of the reference circles of the fifth gear and the sixth gear; when the gear rack rotates to the lowest position, the sharp corner of the second star wheel and the sharp corner of the third star wheel can collide with the sharp corner of the first star wheel; when the gear rack rotates to the highest position, the sharp corner of the second star wheel and the sharp corner of the third star wheel cannot collide with the sharp corner of the first star wheel; under the action of gravity, in a natural state, the gear rack is positioned at the lowest part of the stroke of the gear rack; the locking device comprises a first ratchet and a pawl, the first ratchet is fixed in position, and the tooth surface of the first ratchet faces the rack; a horizontal blind hole and a vertical hole are arranged in the rack, the opening of the horizontal blind hole is positioned on one surface of the rack facing the first ratchet strip, and the lower end of the vertical hole is communicated with the middle part of the horizontal blind hole; a first clamping block is arranged in the horizontal hole, and the end, close to the first ratchet bar, of the first clamping block is hinged with the pawl; a first spring is arranged between the first clamping block and the blind end of the horizontal blind hole; a first operating rod is arranged in the vertical hole, and an inclined plane is arranged at the lower end of the first operating rod, which is far away from the first ratchet strip; a triangular groove which is matched with the upper end of the first operating rod is arranged at the position where the upper side surface of the first clamping block is contacted with the first operating rod, and the matching means that the triangular groove can just accommodate the lower end of the first operating rod; the upper end of the vertical hole is provided with a first electromagnet, the upper end of the first operating rod is provided with a magnet, and the polarity of the upper end of the magnet is the same as that of the lower end of the first electromagnet; the side surface of the middle of the first operating rod facing the first ratchet strip is provided with a first protrusion, the position of the rack close to the first protrusion is hinged with a direction-finding block, one side of the direction-finding block facing the first ratchet strip is provided with a sharp corner, one side of the direction-finding block far away from the first ratchet strip is provided with a second protrusion, and the second protrusion is positioned below the first protrusion.

The diameter of the first gear is smaller than that of the second gear, the diameter of the second gear is larger than that of the fourth gear, and the diameter of the fourth gear is smaller than the maximum diameter of the first star wheel.

Compared with the prior art, the invention has the following outstanding beneficial effects:

1. the electric energy is saved by the self gravity descending;

2. the slow descending speed cannot be changed due to the abrasion of parts, and the performance is stable;

3. the slow descending speed does not change obviously due to different weights of users.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Fig. 2 is a schematic structural diagram of an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of the second embodiment of the present invention.

FIG. 4 is a schematic diagram of a third structure of the embodiment of the present invention.

Fig. 5 is a schematic diagram of a fourth structure according to the embodiment of the present invention.

Fig. 6 is a schematic structural diagram of a lifting device and a locking device in the fourth embodiment of the present invention.

Fig. 7 is a schematic structural diagram of a fifth embodiment of the present invention.

Fig. 8 is a top view of a funnel in a fifth embodiment of the present invention.

Fig. 9 is a schematic structural diagram of a lifting device and a locking device in the fifth embodiment of the present invention.

Fig. 10 is a six-structure diagram of the embodiment of the invention.

Fig. 11 is a schematic structural view of a lifting device in the sixth embodiment of the present invention.

Fig. 12 is a cross-sectional view taken along line a-a of fig. 10 in accordance with the present invention.

Detailed Description

The invention is further described with reference to the drawings and the detailed description.

As shown in fig. 1, the present invention is a lifting device, and the embodiment of the lifting device includes a rack 7, a motor 9, a gear rack 10, a housing 8, and a plurality of gears, wherein the motor 9, the gear rack 10, the housing 8, and the plurality of gears are located inside the housing 8.

The rack 7 is vertically placed and penetrates through the shell 8, the rack 7 is connected with an object to be lifted, the rack 7 is meshed with the first gear 1, the first gear 1 and the second gear 2 jointly form a duplicate gear, and a shaft of the duplicate gear is installed on the shell 8. The output shaft of the motor 9 is connected with a third gear 3, and the third gear 3 is meshed with the second gear 2.

The gear rack 10 is hinged with the shaft where the first gear 1 and the second gear 2 are located, the rotation angle of the gear rack 10 is limited by the shell 8, and the limiting structure can be the external shape of the shell 8 or a protrusion in the shell 8. The motor 9 is fixedly connected with the gear frame 10. Since the carrier 10 rotates about the axis of the second gear 2, the third gear 3 can always mesh with the second gear 2 during the rotation.

The four-gear 4 is arranged below the second gear 2, the four-gear 4 is meshed with the second gear 2, the four-gear 4 is fixedly connected with a coaxial first star wheel 11, shafts of the four-gear 4 and the first star wheel 11 are arranged on the shell 8, a fifth gear 5 and a sixth gear 6 which are mutually meshed are arranged on the gear frame 10, and the fifth gear 5 and the sixth gear 6 are respectively fixedly connected with a coaxial second star wheel 12 and a coaxial third star wheel 13, the three star wheels are positioned on the same vertical plane, and the requirements that the sum of the maximum radiuses (namely the distance between the sharp corners and the circle centers) of the ① second star wheel 12 and the third star wheel 13 is smaller than the sum of the indexing circle radiuses of the fifth gear 5 and the sixth star wheel 6 are met so as to ensure that the second star wheel 12 and the third star wheel 13 cannot collide with each other when the gear frame 10 rotates to the lowest position, the sharp corners of the second star wheel 12 and the third star wheel 13 and the sharp corners of the first star wheel 11 can not collide with each other when the gear frame 10 rotates to the lowest position, and the star wheel carrier can not collide with the sharp corners of the first star wheel 12 and the highest star wheel 10 under the action of the natural stroke.

The working principle of the lifting device is as follows: when an object to be lifted drives the rack 7 to descend, the first gear 1 rotates clockwise, the second gear 2 drives the fourth gear 4 to rotate anticlockwise, the first star wheel 11 rotates anticlockwise, the sharp corner of the first star wheel 11 collides with the sharp corner of the second star wheel 12 firstly, the second star wheel 12 rotates clockwise, the fifth gear 5 rotates clockwise, the sixth gear 6 rotates anticlockwise, the third star wheel 13 rotates anticlockwise, the sharp corner of the first star wheel 11 collides with the third star wheel 13 which rotates anticlockwise, the third star wheel 13 is reversed, namely rotates clockwise, the sixth gear 6 rotates clockwise, the fifth gear 5 rotates anticlockwise, the second star wheel 12 rotates anticlockwise, the next sharp corner of the first star wheel 11 collides … … with the second star wheel 12 which rotates anticlockwise, and the collision is repeated, the rotating speed of the first star wheel 11 is always controlled at a lower speed, namely, the process of slowly descending the rack 7 is realized. The slow descending process is realized in a mechanical mode, and the motor 9 is not required to be started, so that the energy loss is reduced; the slow descending process is realized in a collision rather than friction mode, so that the friction coefficient change caused by the abrasion of parts and the change of the slow descending speed are avoided.

When an object needing to be lifted needs to be lifted, the motor 9 is started, the motor 9 drives the third gear 3 to rotate clockwise, the third gear 3 drives the second gear 2 to rotate anticlockwise, meanwhile, the first gear 1 rotates anticlockwise, and the first gear 1 drives the rack 7 to slowly lift; meanwhile, the third gear 3 is subjected to the counterclockwise moment acted by the second gear 2, the gear frame 10 is subjected to the clockwise moment acted by the third gear 3, the moment drives the gear frame 10 to rotate clockwise at the position of the double-dot chain line in the figure, and the second star wheel 12 and the third star wheel 13 do not collide with the first star wheel 11 any more, so that energy loss is avoided.

In the optimized scheme, in order to obtain a better speed reduction effect, the diameter of the first gear 1 is smaller than that of the second gear 2, the diameter of the second gear 2 is larger than that of the fourth gear 4, and the diameter of the fourth gear 4 is smaller than the maximum diameter (namely twice of the distance between the sharp corner and the circle center) of the first star wheel 11.

The present invention may be used in a variety of mechanical applications, the following of which are specific implementations. The structure of the lifting device in the following embodiments is specific to the present invention, and the composition and connection relationship thereof are shown in the above specific embodiments, and the repetitive portions thereof will not be described below.

The first embodiment is a lifting device.

In an embodiment, the lifting device further includes a locking device in addition to the above-mentioned lifting device. The object to be lifted can be an operation table top, a material platform and the like, and the table top or the platform is fixedly connected with the rack 7 after the object to be lifted is lifted.

As shown in fig. 2, said locking device comprises a first ratchet 15 and a pawl 23, said first ratchet 15 is fixed in position, and the tooth surface of said first ratchet 15 faces said rack 7. The rack 7 is internally provided with a horizontal blind hole and a vertical hole, the opening of the horizontal blind hole is positioned on one surface of the rack 7 facing the first ratchet 15, and the lower end of the vertical hole is communicated with the middle part of the horizontal blind hole. A first block 16 is arranged in the horizontal hole, and the end of the first block 16 close to the first ratchet 15 is hinged with the pawl 23. A first spring 17 is arranged between the first clamping block 16 and the blind end of the horizontal blind hole. A first operating rod 18 is arranged in the vertical hole, and an inclined surface is arranged at the lower end of the first operating rod 18 far away from the first ratchet strip 15. A triangular groove which is matched with the upper end of the first operating rod 18 is arranged at the position where the upper side surface of the first clamping block 16 is contacted with the first operating rod 18, and the matching means that the triangular groove can just accommodate the lower end of the first operating rod 18. The upper end of the vertical hole is provided with a first electromagnet 14, the upper end of a first operating rod 18 is provided with a magnet 19, and the polarity of the upper end of the magnet 19 is the same as that of the lower end of the first electromagnet 14. The middle side of the first operating rod 18 facing the first ratchet 15 is provided with a first protrusion 21, the rack 7 is hinged with a direction-finding block 20 at a position close to the first protrusion 21 for detecting the moving direction of the rack 7, the direction-finding block 20 has a sharp corner facing the first ratchet 15, the direction-finding block 20 is provided with a second protrusion 22 at a side far away from the first ratchet 15, and the second protrusion 22 is positioned below the first protrusion 21.

The rack 7 can be clamped by the pawl 23 and the first ratchet strip 15, so that the rack is prevented from falling randomly. When the first electromagnet 14 is energized, the magnet 19 and the first operating lever 18 move downward due to the repulsion of like poles. Because rack 7 is metal or other magnetic-attracting materials, after the outage, because magnet 19 can adsorb on the lateral wall of its place hole, so can not upwards remove by oneself. When the first operating rod 18 moves downwards, the first clamping block 16 is pushed to the end far away from the first ratchet 15 by the combined action of the inclined surface at the lower end of the first operating rod 18 and the groove, the pawl 23 can not clamp the first ratchet 15 any more, and the rack 7 can fall; when the rack 7 moves downwards, the sharp corner of the direction-finding block 20 can rotate upwards under the action of the first ratchet strip 15, when the rack 7 ascends under the driving of the motor 9, the sharp corner of the direction-finding block 20 rotates downwards under the action of the first ratchet strip 15, meanwhile, the second protrusion 22 rotates upwards, the second protrusion 22 drives the first operating rod 18 to move upwards through the first protrusion 21, the first fixture block 16 is released, the pawl 23 can touch the first ratchet strip 15, and therefore the rack 7 can be clamped at any time after the motor 9 stops, and the rack 7 is prevented from automatically falling.

The second embodiment is a medical auxiliary device, which can be used for helping pregnant and lying-in women, old and weak patients or disabled people to sit up.

As shown in fig. 3, a ring 24 is fixedly connected to the lower end of the rack 7 of the lifting device. The housing of this embodiment may be installed in a ceiling or other device, or a ceiling or the like may be used as the housing, and thus fig. 3 omits a specific shape of the housing.

The operation flow is as follows: when a user sits down, the arm passes through the ring 24 at the lower end of the rack 7, the ring 24 is sleeved at the armpit, and the user is driven to slowly sit down through the device. When the user stands up, the arm passes through the ring 24 at the lower end of the rack 7, the motor 9 is started, and the user is driven to slowly stand up through the device.

The third embodiment is a nursing auxiliary device which can be used for helping pregnant and lying-in women, old and weak patients or disabled people to sit up in a toilet.

As shown in fig. 4, the main body of the lifting device is partially positioned below the floor, the upper end of the rack 7 passes through a hole on the floor to expose the floor, and the upper end of the rack 7 is fixedly connected with the armpit support 25. Also, fig. 4 omits the specific shape of the housing. The switch of the motor 9 is positioned on the rack 7 below the armpit support 25 and is electrically connected with the motor 9 through an electric wire.

The operation flow is as follows: when the patient goes to the toilet, the armpit support 25 is placed under the armpit, and under the action of the weight, the lifting device drives the patient to slowly sit down. When the patient stands up, the arm passes through the armpit support 25 at the lower end of the rack 7, the motor 9 is started, and the patient is driven to slowly stand up through the device.

The fourth embodiment is a teaching aid, which is used for lifting teaching screens and also can be used for lifting demonstration screens in business activities.

As shown in fig. 5 and 6, the lifting device is located behind the screen 26 and is fixedly connected with a wall or other supporting structures, and the rack 7 is fixedly connected with the screen 26.

The embodiment further comprises a locking device, wherein the locking device comprises a second ratchet strip 27, the second ratchet strip 27 is fixedly connected with the shell 8, and the tooth surface of the second ratchet strip 27 faces the rack 7. The rack 7 is internally provided with a horizontal blind hole and a vertical hole, the opening of the horizontal blind hole is positioned on one surface of the rack 7 facing the second ratchet strip 27, the upper end of the vertical hole is communicated with the middle part of the horizontal blind hole, and the lower end of the vertical hole is opened. A second fixture block 28 is arranged in the horizontal hole, one end of the second fixture block 28 is exposed out of the hole, and an inclined plane is arranged on the upper side of the exposed end. And a second spring 29 is arranged between the second clamping block 28 and the blind end of the horizontal blind hole. The vertical hole is internally provided with a second operating rod 30, the diameter of the second operating rod 30 is equal to the inner diameter of the vertical hole in which the second operating rod is positioned, the lower end of the second operating rod 30 is exposed, and the upper end of the second operating rod is provided with an inclined plane far away from the second ratchet strip 27. The position where the lower side surface of the second clamping block 28 contacts the second operating rod 30 is provided with a triangular groove which is matched with the upper end of the second operating rod 30, and the matching means that the triangular groove can just accommodate the upper end of the second operating rod 30.

The operation flow is as follows: when the screen 26 is lowered, the second operating lever 30 is pushed up, the second latch 28 is retracted by the second operating lever 30, and the second operating lever 30 is not rebounded by the frictional force of the vertical hole. The screen 26 is slowly lowered by gravity.

When the screen 26 is raised, the motor 9 is started, and the screen 26 is slowly raised by the device.

The fifth embodiment is a bulk cargo hopper which can be used for bulk cargo loading in ports and cargo yards.

As shown in fig. 7 and 8, the bulk hopper comprises a hopper 34, a supporting frame 35, a rubber skirt 37, a lifting device and a blocking device.

The funnel 34 is supported by the support frame 35. The feed opening of the hopper 34 is provided with a rod-shaped buffer 39 which is horizontally arranged, so that the cargo leakage speed and flow rate are effectively controlled, and the impact on the box body of the transport vehicle is reduced. The lower end is provided with a fixed skirt 36. The rubber skirt board 37 is nested on the fixed skirt board 36. Rubber skirtboard 37 accessible elevating gear reciprocate to can adapt to the car of various co-altitude, through the combined action of fixed skirtboard 36 and rubber skirtboard 37, do not spill over when making the goods load, can lock bulk cargo floating dust simultaneously, reduce the raise dust, reduce air pollution.

As shown in fig. 9, the lifting device housing 8 is fixedly connected to the hopper 34. The rack 7 is fixedly connected with the rubber apron board 37.

The locking device comprises a third ratchet 31, the third ratchet 31 is fixedly connected with the fixed skirt plate 36, and the tooth surface of the third ratchet 31 faces the rack 7. A horizontal blind hole is arranged in the rack 7, and the opening of the horizontal blind hole is positioned on one surface of the rack 7 facing the third ratchet 31. A third clamping block 32 is arranged in the horizontal hole, the third clamping block 32 is a magnetic clamping block, specifically, the third clamping block can be made of a magnetic metal material or one end of the third clamping block is fixedly connected with a magnet, and an inclined surface is arranged on the upper side surface of the third clamping block 32 close to the third ratchet strip 31. And a second electromagnet 33 is arranged at the blind end of the horizontal blind hole.

After the second electromagnet 33 is powered on, when the polarities of the second electromagnet 33 and the third clamping block 32 facing to each other are the same, the third clamping block 32 is pushed out by the repulsive force, and the rubber skirt 37 can be clamped by the third clamping block 32 and the third ratchet 31 structure, so that the rubber skirt is prevented from falling randomly. When the rubber apron 37 is required to fall, the second electromagnet 33 is electrified with reverse current, the polarity of the second electromagnet 33 is changed, the third clamping block 32 is attracted by attraction force and is sucked into the hole, so that the rubber apron 37 can fall freely, and when the rubber apron 37 falls to a proper position, the second electromagnet 33 is electrified with forward current to push out the third clamping block 32 and clamp the rubber apron 37.

The operation flow is as follows: when the automobile unloading device is used, an automobile is firstly driven to the lower part of the unloading opening, the rubber skirt board 37 descends through gravity according to the height of the automobile, and the height of the rubber skirt board 37 is gradually increased through the lifting device along with the accumulation of goods in a carriage until the loading is finished.

The sixth embodiment is medical equipment, and is particularly used for lifting a bed board of a hospital bed.

As shown in fig. 10 and 11, the present embodiment includes a bed 40, the lifting device and the locking device.

The bed body 40 is provided with a fixed bed board 44 and a lifting bed board 42, and the lifting bed board 42 is hinged with the fixed bed board 44 through one side edge. A beam 43 is arranged under the bed plate. For convenience of description, the direction of the elevation plate 42 is set to the front, and the direction of the fixed plate 44 is set to the rear.

Two ends of the connecting rod 41 are respectively hinged with the lifting bed plate 42 and the rack 7. The rack 7 is horizontally arranged. The cross beam 43 is provided with a hole along the front-back direction of the bed body 40, and the rack 7 passes through the hole.

As shown in fig. 12, the locking device specifically includes: the rack 7 and the cross beam 43 are respectively provided with a horizontal hole along the width direction of the bed body 40, a fourth fixture block 46 is arranged in the horizontal hole of the rack 7, one end of the fourth fixture block 46 is exposed, and an inclined plane is arranged at the rear side of the exposed end. The other end of the fourth latch 46 is provided with a third spring 47. One end of the horizontal hole of the cross beam 43 is communicated with the hole where the rack 7 is located on the cross beam 43, a third operating rod 45 is arranged in the horizontal hole of the cross beam 43, one end of the third operating rod 45 can touch the rack 7, and the other end of the third operating rod is exposed out of the hole, so that the operation of a user is facilitated.

The operation flow is as follows: when the lifting bed plate 42 is lifted, the fourth block 46 is blocked in the horizontal hole on the cross beam 43, so as to fix the rack 7. When the lifting bed plate 42 needs to fall down, the third operating rod 45 is pressed down to push the fourth fixture block 46, and the lifting bed plate 42 is slowly fallen down through the lifting device under the action of gravity.

When the lifting bed plate 42 needs to be lifted, the motor 9 is started, the rack 7 moves backwards, and the bed plate is driven to be slowly lifted through the lifting device.

It should be noted that while the invention has been described in detail with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various obvious changes can be made therein without departing from the spirit and scope of the invention.

Claims

1. The utility model provides an operation mesa elevating gear which characterized in that: the gear locking device comprises a rack, a motor, a gear rack, a shell, a plurality of gears and a locking device; the rack is vertically arranged and penetrates through the shell, the rack is meshed with the first gear, the first gear and the second gear form a duplicate gear together, and a shaft of the duplicate gear is arranged on the shell; the output shaft of the motor is connected with a third gear, and the third gear is meshed with the second gear; the gear rack is hinged with a shaft where the first gear and the second gear are located; the motor is fixedly connected with the gear frame; a fourth gear is arranged below the second gear, is meshed with the second gear and is fixedly connected with a coaxial first star wheel; the shaft of the fourth gear and the shaft of the first star wheel are arranged on the shell; the gear rack is provided with a fifth gear and a sixth gear which are meshed with each other, and the fifth gear and the sixth gear are respectively and fixedly connected with a second star wheel and a third star wheel which are coaxial; the three star wheels are positioned on the same vertical plane, and the sum of the maximum radiuses of the second star wheel and the third star wheel is smaller than the sum of the radiuses of the reference circles of the fifth gear and the sixth gear; when the gear rack rotates to the lowest position, the sharp corner of the second star wheel and the sharp corner of the third star wheel can collide with the sharp corner of the first star wheel; when the gear rack rotates to the highest position, the sharp corner of the second star wheel and the sharp corner of the third star wheel cannot collide with the sharp corner of the first star wheel; under the action of gravity, in a natural state, the gear rack is positioned at the lowest part of the stroke of the gear rack; the locking device comprises a first ratchet and a pawl, the first ratchet is fixed in position, and the tooth surface of the first ratchet faces the rack; a horizontal blind hole and a vertical hole are arranged in the rack, the opening of the horizontal blind hole is positioned on one surface of the rack facing the first ratchet strip, and the lower end of the vertical hole is communicated with the middle part of the horizontal blind hole; a first clamping block is arranged in the horizontal hole, and the end, close to the first ratchet bar, of the first clamping block is hinged with the pawl; a first spring is arranged between the first clamping block and the blind end of the horizontal blind hole; a first operating rod is arranged in the vertical hole, and an inclined plane is arranged at the lower end of the first operating rod, which is far away from the first ratchet strip; a triangular groove which is matched with the lower end of the first operating rod is arranged at the position where the upper side surface of the first clamping block is contacted with the first operating rod, and the matching means that the triangular groove can just accommodate the lower end of the first operating rod; the upper end of the vertical hole is provided with a first electromagnet, the upper end of the first operating rod is provided with a magnet, and the polarity of the upper end of the magnet is the same as that of the lower end of the first electromagnet; a first protrusion is arranged on the side surface of the middle of the first operating rod facing the first ratchet strip, a direction-finding block is hinged to the position, close to the first protrusion, of the rack, a sharp corner is arranged on one side, facing the first ratchet strip, of the direction-finding block, a second protrusion is arranged on one side, far away from the first ratchet strip, of the direction-finding block, and the second protrusion is located below the first protrusion; when an object needing to be lifted drives the rack to descend, the first star wheel rotates anticlockwise, the sharp corner of the first star wheel collides with the sharp corner of the second star wheel firstly, the second star wheel rotates clockwise, the fifth gear rotates clockwise simultaneously to drive the sixth gear to rotate anticlockwise, the third star wheel rotates anticlockwise simultaneously, the sharp corner of the first star wheel collides with the third star wheel rotating anticlockwise immediately, the third star wheel is made to rotate reversely, namely, the sixth gear rotates clockwise simultaneously to drive the fifth gear to rotate anticlockwise, the second star wheel rotates anticlockwise simultaneously, and the next sharp corner of the first star wheel collides with the second star wheel rotating anticlockwise immediately.

2. An operating table lifting device as claimed in claim 1, wherein: the diameter of the first gear is smaller than that of the second gear, the diameter of the second gear is larger than that of the fourth gear, and the diameter of the fourth gear is smaller than the maximum diameter of the first star wheel.