CN109869455B

CN109869455B - Lifting table

Info

Publication number: CN109869455B
Application number: CN201910266765.2A
Authority: CN
Inventors: 区赞勋
Original assignee: Guangzhou Jinxin Furniture Co ltd
Current assignee: Guangzhou Jinxin Furniture Co ltd
Priority date: 2019-04-03
Filing date: 2019-04-03
Publication date: 2024-04-16
Anticipated expiration: 2039-04-03
Also published as: WO2020199409A1; KR20200117990A; CN109869455A; KR102386620B1; JP7034510B2; JP2021520237A; TW202037826A; TWI730696B

Abstract

The invention provides a lifting table. The lifting table comprises a table top, an energy conversion device (30) and a leg assembly, wherein the energy conversion device (30) is connected below the table top, the energy conversion device (30) is used for converting elastic potential energy into auxiliary energy for lifting the table top, the lifting table comprises a torsion spring (31), a middle shaft (33) and a speed changer (32), a first end of the torsion spring (31) is connected to an input part of the speed changer (32), the middle shaft (33) is connected to an output part of the speed changer (32), the rotating speed of the input part is smaller than that of the output part, the leg assembly is connected with the middle shaft (33), and in the forward rotation or reverse rotation process of the middle shaft (33), the leg assembly is shortened or lengthened to enable the table top to descend or ascend. According to the lifting table disclosed by the invention, the elastic potential energy stored by the torsion spring is not completely released in the whole process of lifting the table top, so that the external force from an operator required by the table top is small.

Description

Lifting table

Technical Field

The invention relates to the field of furniture or production operation equipment, in particular to a lifting table capable of changing height, which can be expressed as a table, a chair, an operation table or a display table and is suitable for household furniture, office furniture, teaching tables and chairs, production operation tables and the like.

Background

The lift table in the prior art is typically manually operated by an operator to change the height of the table top, and in order to reduce the work difficulty of the operator, the lift table may include an energy storage device (hereinafter also simply referred to as an energy storage device). For example, in a lift table using a torsion spring as an energy storage device, the torsion spring may be rotated several turns about its own axis to accumulate elastic potential energy, and then released to provide auxiliary energy to assist in raising the table when raising the table is desired. Along with the lifting of the table top, the elastic potential energy of the torsion spring and the gravitational potential energy of the table top are mutually converted.

Assuming a maximum travel of 500mm for the table top of the lift table to rise from a lowermost position (e.g. 700mm from the floor) to an uppermost position (e.g. 1200mm from the floor), the torsion spring needs to rotate 5 turns during the entire rise of the table top, i.e. every turn of the torsion spring, the table top rises by 100mm.

Assuming that the torsion arm length of the torsion spring is 0.025m, the torsion spring needs to have a torque of 0.75 N.m when rotating for one turn, namely, the elastic potential energy of 0.75 N.m is stored. When the torsion spring rotates one turn, the torsion force generated by the torsion spring is 0.75 N.m/0.025 m=30N; when the torsion spring rotates two times, the torsion force generated by the torsion spring is 60N.

Assuming a total load of 150N for the table, it is now desired to raise the table from the lowest position to the highest position. The torsion spring is rotated for 5 circles in advance, the elastic potential energy stored by the torsion spring is 5 multiplied by 0.75N.m=3.75N.m, the torsion spring externally generates torsion force of 150N, and the torsion force is balanced with the total load of the table top. At this point, giving the table an upward initial momentum, the table can be raised.

When the table surface rises by 100mm, the torsion spring rotates one circle (rotates in the direction opposite to the preset direction) to release potential energy of 0.75N.m, at the moment, the potential energy stored by the torsion spring is reduced to 3.75N.m-0.75N.m=3N.m, and the corresponding external torsion force is 3 N.m/0.025 m=120N. In order to maintain the table top at a constant elevation, an additional 30N upward force is required to be applied to the table top by the operator.

Similarly, in order to ensure stable lifting of the table top, an upward force (hereinafter referred to as an external force) applied to the table top by an operator needs to be continuously increased during the continuous lifting of the table top. When the table surface rises by 200mm, the required external force is 60N; when the table surface is raised by 400mm, the required external force is 120N. The continuously increased external force demand brings a larger burden to operators.

Disclosure of Invention

The object of the present invention is to overcome or at least alleviate the above-mentioned drawbacks of the prior art and to provide a lifting platform which provides a continuously stable auxiliary force.

The invention provides a lifting table, which comprises a table top, an energy conversion device and a leg assembly, wherein the energy conversion device and the leg assembly are connected below the table top,

the energy conversion device is used for converting elastic potential energy into auxiliary energy for lifting the table top and comprises a torsion spring, a middle shaft and a speed changer, wherein the first end of the torsion spring is connected with an input part of the speed changer, the middle shaft is connected with an output part of the speed changer, the rotating speed of the input part is smaller than that of the output part,

the leg assembly is connected with the central shaft, and shortens or extends to enable the table top to descend or ascend in the process that the central shaft rotates forwards or reversely.

In at least one embodiment, the transmission is a planetary gear transmission comprising a ring gear, a sun gear, a plurality of planet gears, and a planet carrier;

the gear ring is fixed, the planet carrier is used as the input part to be connected with the torsion spring, and the sun gear is used as the output part to be connected with the middle shaft;

the torsion spring is sleeved on the periphery of the center shaft and is coaxially arranged with the center shaft.

In at least one embodiment, the transmission includes a large gear as the input member and a small gear as the output member, the axes of rotation of the large gear and the small gear being non-collinear.

In at least one embodiment, the lift table further comprises a cross beam secured to the table top, the energy conversion device further comprising a clutch, a brake fork, and a drive assembly;

the clutch is fixed on the cross beam, and the middle shaft can pass through the clutch in a rotating way around the axis of the middle shaft;

the brake fork is fixed on the middle shaft and can be selectively locked or released by the clutch; when the brake fork is locked by the clutch, the middle shaft cannot rotate; when the brake fork is released by the clutch, the middle shaft can rotate around the axis of the middle shaft;

the transmission assembly is coupled to the second end of the torsion spring, and the second end of the torsion spring can be rotated relative to the first end by operating the transmission assembly to cause the torsion spring to accumulate elastic potential energy.

In at least one embodiment, the leg assembly includes a first leg, a second leg, and a synchronous lifting device, the first leg being capable of moving toward or away from the second leg in an axial direction of the second leg,

the synchronous lifting device comprises:

a support frame in a strip shape;

the two driving wheels are arranged at two end parts of the supporting frame;

the annular transmission piece is tightly sleeved on the two transmission wheels by the two transmission wheels; and

the synchronous connector is fixed on the annular transmission piece; wherein,

the center shaft is connected with the annular transmission piece, the support frame is fixedly connected to the first leg, and the synchronous connector is fixedly connected to the second leg.

In at least one embodiment, the first leg is sleeved on the outer periphery of the second leg.

In at least one embodiment, the leg assemblies are two, one on each side of the energy conversion device in the axial direction.

In at least one embodiment, the energy conversion device further comprises an outer stub shaft movably nested with the central shaft in an axial direction of each other at an end of the central shaft.

In at least one embodiment, a spring is provided at the junction of the outer stub shaft and the central shaft, the outer stub shaft being able to be brought close to the central shaft by squeezing the spring.

In at least one embodiment, the leg assembly further comprises a pressure cylinder, the cylinder body of the pressure cylinder is fixedly connected with the support frame, and the piston rod of the pressure cylinder is fixedly connected with the second leg.

In at least one embodiment, the piston of the pressure cylinder divides the cylinder body into a first chamber and a second chamber, the first chamber and the second chamber being in fluid communication, the piston rod extending from the second chamber out of the cylinder body,

the cylinder is divided into a first region and a second region in the axial direction, the second region is closer to the extending end of the piston rod than the first region,

in the first region, the inner diameter of the cylinder body becomes gradually larger in a direction from the first chamber to the second chamber, and in the second region, the inner diameter of the cylinder body is kept constant in a direction from the first chamber to the second chamber.

According to the lifting table disclosed by the invention, the elastic potential energy stored by the torsion spring is not completely released in the whole process of lifting the table top, so that the external force from an operator required by the table top is small.

Drawings

Fig. 1 is a schematic structural view of a main body portion of a lift table according to an embodiment of the present invention.

Fig. 2 is a schematic structural view of an energy conversion device according to an embodiment of the present invention.

Fig. 3 and 4 are schematic structural views of a transmission according to an embodiment of the present invention.

Fig. 5 is a schematic structural view of a synchronous lifting device according to an embodiment of the present invention.

Fig. 6 is a schematic structural view of a leg assembly according to one embodiment of the present invention.

FIG. 7 is a schematic illustration of a portion of the structure of a leg assembly and cross-beam assembly according to one embodiment of the invention.

Fig. 8 is a schematic structural view of a pressure cylinder according to an embodiment of the present invention.

Description of the reference numerals

10 cross beams;

a 20 leg; 21 a first leg; 22 second leg;

30 energy conversion means; 31 torsion springs;

a 32 transmission; 321 planet carrier; 322 sun gear; 323 planet gears; 324 ring gear; 325 a housing;

33, a central axis; 34 outer minor axis; 341 springs; a 35 clutch; 351 clutch switch; 36 brake fork; 37 drive assembly; 371 handles; 372 staff gauge;

40 synchronous lifting device; 41 support frames; 42 drive chain; 43 a synchronous connector; a 44 phase connector; 441 connection ring;

a 50-pressure cylinder; a 51 cylinder; 52 piston rod; 53 pistons.

Detailed Description

Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific illustrations are for the purpose of illustrating how one skilled in the art may practice the invention, and are not intended to be exhaustive of all of the possible ways of practicing the invention, nor to limit the scope of the invention.

The specific structure and method of use of the lift table according to the present invention will be described below with reference to fig. 1 to 8.

The lifting platform of the present embodiment includes a table top (not shown), a hollow cross beam 10 fixed under the table top, an energy conversion device 30 accommodated in an inner cavity of the cross beam 10, two hollow legs 20 fixed at both sides of the cross beam 10, a synchronous lifting device 40 accommodated in an inner cavity of the legs 20, and a pressure cylinder 50.

The energy conversion device 30 is used for providing first auxiliary energy (first auxiliary power) during lifting of a lifting portion of the lifting platform (the lifting portion mainly comprises a table top, and the table top is only used for replacing the lifting portion when the lifting portion is mentioned for convenience of description), and elastic potential energy stored by the energy storage device in the energy conversion device 30 can be converted into gravitational potential energy of the table top, so that the burden of an operator is reduced.

Referring to fig. 2, the energy conversion device 30 includes a torsion spring 31, a transmission 32, a central shaft 33, an outer stub shaft 34, a clutch 35, a brake fork 36, and a transmission assembly 37.

The clutch 35 is fixed to the cross member 10, and the center shaft 33 passes through the clutch 35 and is rotatable about its own axis with respect to the clutch 35. The brake fork 36 is fixed to the bottom bracket 33, and the brake fork 36 can be selectively locked or released by the clutch 35 by the clutch switch 351. When the brake fork 36 is released by the clutch 35, the bottom bracket 33 can rotate in the forward or reverse direction; when the brake fork 36 is locked by the clutch 35, the bottom bracket 33 cannot rotate.

The torsional spring 31 is sleeved on the periphery of the center shaft 33, a first end of the torsional spring 31 is connected with the center shaft 33 through the transmission 32, and a second end of the torsional spring 31 is connected with the transmission assembly 37. The transmission assembly 37 is used for transmitting an external force to the second end of the torsion spring 31 to rotate the torsion spring 31 around its own axis. In this embodiment, the transmission assembly 37 is a worm gear assembly, the transmission assembly 37 is connected to the handle 371, the rotation axis of the handle 371 is perpendicular to the rotation axis of the torsion spring 31, and an operator can transmit an external force to the torsion spring 31 by rotating the handle 371. An indication device 372 is also arranged on the wall of the crossbeam 10, and the rotation amplitude of the handle 371 can be displayed by the indication device 372. The indication device 372 may be a mechanical pointer, and is linked with the handle 371 through a transmission member such as a gear rack; the rotation amplitude of the handle 371 may be measured by a photoelectric sensor or the like. The operator can know the relative amount of energy stored by the torsion spring 31 through the indicating means 372.

The implementation mode of accumulating elastic potential energy by the torsion spring 31: the clutch switch 351 is controlled so that the brake fork 36 is locked by the clutch 35, and at this time, the handle 371 is turned, and the first end of the torsion spring 31 is fixed and the second end is turned.

The implementation mode of releasing elastic potential energy by the torsion spring 31: the handle 371 is locked, and the second end of the torsion spring 31 is fixed, and at this time, the clutch switch 351 is controlled to release the brake fork 36 by the clutch 35, and the first end of the torsion spring 31 rotates relative to the second end and drives the center shaft 33 to rotate.

The transmission 32 connects the torsion spring 31 and the bottom bracket 33 such that rotation of the torsion spring 31 is transmitted to the bottom bracket 33 in an amplified manner. As will be appreciated by the reader below, the number of turns of the central shaft 33 is fixed corresponding to a certain distance of lifting of the table top, whereas if the central shaft 33 is rotated several turns, the torsion spring 31 is rotated only by a small angle, the elastic potential energy of the torsion spring 31 is not completely released during lifting of the table top. For the same rising distance, the change of the assist force provided by the torsion spring 31 in this embodiment is small compared to the adjustment process in which the elastic potential energy of the torsion spring 31 is completely released, so that the rising of the table top is smoother and the external force required to be dynamically supplemented by the operator is smaller.

With reference to fig. 3 and 4, the specific structure and function of the transmission 32 according to the present embodiment will be described below. In order to save space in the inner cavity of the cross beam 10 and facilitate the positioning of the central shaft 33 and the torsion spring 31, the transmission 32 used in the present embodiment is a planetary gear transmission. The transmission 32 includes a carrier 321, a sun gear 322, three planet 323 ring gears 324, and a housing 325. The carrier 321 is adapted to be fixed to a first end of the torsion spring 31, and the planetary wheel 323 is rotatably fixed to the carrier 321 about its own axis. The central shaft 33 passes axially through the sun gear 322 and is connected to the sun gear 322 in a rotationally fixed manner. The outer periphery of the ring gear 324 has notches that mate with protrusions in the housing 325 so that the ring gear 324 is held by the housing.

The operation of the transmission 32 corresponds to the release of elastic potential energy by the torsion spring 31. In this process, the ring gear 324 is stationary, the carrier 321 is active, the sun gear 322 is passive, and an accelerating transmission effect from the carrier 321 to the sun gear 322 is achieved.

The benefits of the present invention of adding transmission 32 are described next by taking a gear ratio (i.e., rotational speed (angular velocity) ratio) between carrier 321 and sun gear 322 of 1:10 as an example. The auxiliary support to the table discussed herein is tentatively not considered to be a consideration of the effects of the cylinder assemblies described below.

Assuming that the torsion arm length of the torsion spring 31 is 0.025m, the torsion spring 31 needs to have a torque of 7.5n·m, i.e., stores a potential energy of 7.5n·m, for each rotation of the torsion spring 31. Thus, the force transmitted to the central shaft 33 through the transmission 32 is 7.5n·m/0.025 m/10=30n per one rotation of the torsion spring 31.

For a table top with a load of 150N that needs to be raised 500mm, it is assumed that the table top is raised 100mm for each rotation of the central shaft 33. When defining the initial state, the torsion spring 31 is preset to rotate forward 5 turns such that the torsion spring 31 stores elastic potential energy of 5×7.5n·m=37.5 n·m, and the force transmitted to the center shaft 33 through the transmission 32 is 37.5n·m/0.025 m/10=150n. At this time, the supporting force provided to the table top by the torsion spring 31 is balanced with the load of the table top, and the table top can be lifted by giving a minute upward initial momentum to the table top.

After the table surface rises by 100mm, the center shaft 33 rotates 1 turn, the torsion spring 31 rotates 1/10 turn (36 °) in the opposite direction to the preset rotation direction, and the torsion spring 31 releases the elastic potential energy of 7.5n·m×1/10=0.75 n·m. At this time, the elastic potential energy stored in the torsion spring 31 is reduced to 37.5n·m-0.75n·m=36.75 n·m, and the force transmitted from the torsion spring 31 to the center shaft 33 through the transmission 32 is reduced to 36.75n·m/0.025 m/10=147N. The supporting force provided to the table top by the torsion spring 31 is reduced by 3N as compared to the initial state. At this time, only the operator is required to additionally provide an upward external force of 3N for the table top, and the table top can still ascend at a constant speed.

Similarly, when the table surface rises by 200mm, the required external force is 6N; when the table surface is raised by 400mm, the required external force is 12N. When the table surface rises by 500mm, the torsion spring 31 rotates in the opposite direction for 5/10 turns (180 degrees) to release the elastic potential energy of 3.75 n.m, at this time, the elastic potential energy stored in the torsion spring 31 is reduced to 37.5 n.m-3.75 n.m=33.75 n.m, and the force transmitted to the center shaft 33 by the torsion spring 31 through the transmission 32 is reduced to 33.75 n.m/0.025 m/10=135N. The supporting force provided to the table top by the torsion spring 31 is reduced by only 15N compared to the initial state.

Thus, the external force provided by the operator during the 500mm ascent of the table is greatly reduced compared to the prior art solution without the use of the transmission 32.

Next, how the table top is lifted by rotating the center shaft 33 will be described with reference to fig. 5 to 7.

The synchronous lifting device 40 connects the center shaft 33 and the legs 20, and not only can the rotation of the center shaft 33 and the conversion between the telescopic movements of the legs 20 be realized by the synchronous lifting device 40, but also the two legs 20 can be ensured to be synchronously telescopic.

Referring to fig. 5, the synchronous lifting device 40 includes a support frame 41, a transmission chain 42, a synchronous connector 43, and a phase connector 44. The support 41 is in a strip shape, two ends of the support 41 are respectively connected with a phase connector 44, and each phase connector 44 comprises a driving wheel. An endless drive chain 42 is stretched over the drive wheels of two phase connectors 44. The synchronizing coupler 43 is fixed to the drive chain 42, and the forward and reverse rotation of the drive chain 42 will cause the synchronizing coupler 43 to reciprocate between the two phase couplers 44. The rotation of the transmission chain 42 is synchronous with the rotation of the transmission wheel, the rotation of the transmission wheel drives the rotation of the connecting ring 441, and the connecting ring 441 can be connected with the middle shaft 33 in a non-rotatable manner; thus, the rotation of the central shaft 33 and the reciprocation of the synchronization coupler 43 are mutually restrained.

Referring to fig. 6, the connection relationship between the synchronous lifting device 40 and the leg 20 will be described. The leg 20 includes first and second leg portions 21, 22 nested within each other, the first and second leg portions 21, 22 being capable of being moved toward and away from each other to effect shortening or lengthening of the leg 20. The support frame 41 of the synchronous lifting device 40 is fixedly connected to the first leg 21 and the synchronous connector 43 is fixedly connected to the second leg 22. Thus, when the relative positions of the first leg 21 and the second leg 22 are changed, the position of the synchronization connector 43 on the support frame 41 is also changed correspondingly, while the connection ring 441 is rotated. In the present embodiment, since the first leg portion 21 and the second leg portion 22 are nested with each other, the first leg portion 21 is fitted around the outer periphery of the second leg portion 22 so that the first leg portion 21 and the second leg portion 22 do not interfere with the position of the synchronization connector 43 when relatively moving.

Next, how the center shaft 33 is connected to the phase connector 44 will be described with reference to fig. 7. The beam assembly (including the beam 10 and the energy conversion device 30) of this embodiment can be easily detached from the leg assembly (including the legs 20, the synchronous lifting device 40, and the pressure cylinder 50 described further below), so that the lifting platform can be independently packaged and transported in the process of being transported from the manufacturer to the customer, saving the logistical cost. Flexible disassembly and assembly of the beam assembly to the leg assembly is achieved by the outer stub shaft 34 and the spring 341. The center shaft 33 (not shown in fig. 6) is provided at both ends with a hollow structure, and the outer stub shaft 34 can be inserted into the inner cavity at the end of the center shaft 33 and connected to the center shaft 33 in a non-rotatable manner, for example, the cross section of the inner cavity at the end of the center shaft 33 and the cross section of the outer stub shaft 34 are both hexagonal. The outer short shaft 34 is sleeved with the middle shaft 33 and provided with a spring 341, and in a natural state, the spring 341 keeps the original length, and the outer short shaft 34 is in an extending state. The outer stub shaft 34 can extend further into the interior cavity of the central shaft 33 upon application of pressure to the outer stub shaft 34 in an axial direction toward the central shaft 33. The cross-sectional shape of the outer stub shaft 34 is adapted to the cross-sectional shape of the annular bore of the phase collar 441 such that the outer stub shaft 34 can extend into the phase collar 441 exactly and rotation of one of the outer stub shaft 34 or the phase collar 441 can drive the other to rotate in phase, the phases of rotation being mutually constrained, i.e. the two are not rotatably connected.

Preferably, the distance between the two legs 20 of the completed lift (approximately equal to the distance between the two connecting rings 441) is smaller than the distance between the protruding ends of the two outer stub shafts 34 of the energy conversion device 30 in the natural state. The outer stub shafts 34 are then at least partially pressed into the central shaft 33 when the beam assembly and the leg assembly are mounted, until both outer stub shafts 34 project into the corresponding phase connection rings 441. The outer stub shaft 34 then partially springs back out of the central shaft 33 under the force of the spring 341, making the beam assembly and leg assembly more securely assembled.

It should be appreciated that the telescoping assembly of the outer stub shaft 34 with the central shaft 33 is not limited to the form described above that allows the outer stub shaft 34 to be nested within the central shaft 33. It is also possible, for example, to arrange the end of the outer stub shaft 34 connected to the central shaft 33 in a hollow structure so that the central shaft 33 can extend partially into the interior of the outer stub shaft 34.

The pressure cylinder 50 (see fig. 8) in the present embodiment provides the second auxiliary energy (second auxiliary power) for raising the table top. In the present embodiment, the pressure cylinder 50 is a pneumatic cylinder, and the cylinder 51 is filled with high-pressure nitrogen gas. The cylinder 51 is fixedly connected to the support 41 or the first leg 21, and the piston rod 52 is fixedly connected to the second leg 22. During the table-top ascent, the piston rod 52 continues to extend out of the cylinder 51 to provide auxiliary power.

Preferably, the inner diameter of the pressure tube 50 is of a special design in order to keep the output force of the piston rod 52 during extension stable. This is because, since the piston rod 52 occupies a certain space inside the cylinder 51, the volume of gas inside the cylinder 51 gradually becomes larger and the pressure of gas inside the cylinder 51 gradually decreases during the outward extension of the piston rod 52. If the surface area of the upper and lower surfaces of the piston 53 remains unchanged, the outward output force of the piston rod 52 will be continuously reduced during the entire outward extension of the piston rod 52. In the preferred embodiment described below, the inner diameter of the cylinder 51 is varied in the axial direction so that the surface areas of the upper and lower surfaces of the piston 53 are correspondingly varied during movement.

The construction of this preferred pressure cylinder 50 is described below with reference to fig. 8.

The interior of the cylinder 51 is divided by the piston 53 into a first chamber C1 and a second chamber C2 in the axial direction, the first chamber C1 being in fluid communication with the second chamber C2.

The cylinder 51 is divided into two regions in the axial direction according to the difference in the inner diameter of the cylinder 51, and the extending direction of the piston rod 52 is defined as "up", and the second region is located above the first region. The cylinder inner diameter of the first region becomes gradually larger and the cylinder inner diameter of the second region remains unchanged in the direction from the first region toward the second region in the axial direction of the cylinder 51.

The piston 53 has a certain elasticity, can be in close contact with the inner wall of the cylinder 51, and is adaptively deformed according to the change of the cylinder inner diameter. During the movement of the piston rod 52 out of the cylinder 51, when the piston 53 moves in the first region, the difference Δs in the surface area of the upper and lower surfaces of the piston 53 (the surface of the piston 53 facing the first chamber C1 is the lower surface thereof, and the surface of the piston 53 facing the second chamber C2 is the upper surface thereof) gradually decreases; while when the piston 53 moves in the second region, the surface area difference Δs' of the upper and lower surfaces of the piston 53 remains unchanged. The broken line portion in fig. 8 is a schematic of several positions in the movement locus of the piston 53, and table 1 shows the surface area differences of the upper and lower surfaces of the piston 53 at the above-described several positions. It should be noted that the cylinder inner diameter design in practical application needs to be combined with the external force applied to the piston rod 52, and takes into consideration the physical state of the high-pressure nitrogen in the cylinder, the structure of the device, the arrangement of the gas valve, and the like.

TABLE 1

The whole process of extending the piston rod 52 is as follows: Δs < Δs', which adaptively compensates for the gas pressure difference in the cylinder 51 during the process, so that the variation of the output force of the piston rod 52 is small and the auxiliary power provided by the pressure cylinder 50 is smooth.

The following describes a lifting operation procedure of the lifting table according to the present embodiment with reference to fig. 1 and 2:

(1) Lifting table is lifted

In the initial state, the clutch switch 351 is in the connected state, and the brake fork 36 is locked by the clutch 35.

The handle 371 is rotated to store energy by the positive rotation of the torsion spring 31, and the torsion spring 31 stores elastic potential energy suitable for the total weight of the table top by combining the reading of the indicating device 372.

The clutch switch 351 is put in an off state. The brake fork 36 is disengaged from the clutch 35, the torsion spring 31 reversely rotates to release elastic potential energy, and the transmission 32 drives the middle shaft 33 and the outer short shafts 34 at the two ends to rotate, so that first auxiliary power is transmitted to the synchronous lifting device.

The table top is brought close to a suspended state with the support of the second auxiliary power provided by the pressure cylinder 50 and the above-mentioned first auxiliary power. At this point the table top can be lifted slightly giving the table top an initial upward momentum and the piston rod 52 of the pressure cylinder 50 is extended. The legs 20 are elongated (the first leg portions 21 are lifted up near uniform speed), and the lifting of the first leg portions 21 on both sides is kept synchronized.

In the process of lifting the table top, an operator can give a certain artificial external force to the table top according to the movement state of the table top.

After the table reaches the desired height, the clutch switch 351 is placed in the connected state and the brake fork 36 is locked by the clutch 35. The extension process of the legs 20 (i.e., the raising process of the table top) is terminated, the height of the raising and lowering table is determined, and the gravitational potential energy of the table top is increased.

(2) The lifting platform descends

The clutch switch 351 is turned off, the brake fork 36 is disengaged from the lock of the clutch 35, and the center shaft 33 and the outer stub shafts 34 at both ends are in a rotatable state.

The lightly pressed table gives the table a downward initial momentum and the table descends under its own weight. During the descending process of the table top, the center shaft 33 rotates forward (relative to the center shaft 33 and the torsion spring 31 rotate reversely during the ascending process of the lifting table), the brake fork 36 and the torsion spring 31 are driven to rotate forward, and the torsion spring 31 stores energy.

After the table top reaches the desired height, the clutch switch 351 is put in the connected state, the brake fork 36 is locked by the clutch 35, the lowering process is terminated, the height of the lifting table is determined, and the gravitational potential energy of the table top is converted into the elastic potential energy of the torsion spring 31.

The present invention has at least one of the following advantages:

(i) The present invention uses the torsion spring 31 to provide a first auxiliary power for the lifting of the lifting platform, and the auxiliary power is transmitted to the center shaft 33 via the transmission 32 and further to the synchronous lifting device 40. The transmission 32 plays a lever-like adjusting role in the transmission process of force and motion, and the transmission transmits the rotation angle of the torsion spring 31 to the center shaft 33 after amplifying, so that the elastic potential energy accumulated by the torsion spring 31 can not be completely released in the whole process of lifting the table top.

(ii) The transmission 32 adopts a planetary gear transmission structure, the torsion spring 31 is connected to the planet carrier 321 which is an input part of the transmission 32, the middle shaft 33 is connected to the sun gear 322 which is an output part of the transmission 32, the torsion spring 31 can be sleeved on the periphery of the middle shaft 33 and arranged coaxially with the middle shaft 33, and the middle shaft 33 can axially pass through the transmission 32, so that the space of the inner cavity of the cross beam 10 is saved.

(iii) The synchronous lifting device 40 is connected with the energy conversion device 30, so that not only is the transmission between the rotation of the center shaft 33 and the telescopic movement of the legs 20 realized, but also the synchronous telescopic movement of the legs 20 arranged in pairs can be ensured.

(iv) The outer short shaft 34 and the middle shaft 33 can relatively move a certain distance in the axial direction, so that the synchronous lifting device 40 and the energy conversion device 30 can be conveniently assembled and disassembled. Manufacturers can produce and package the leg assemblies, the beam assemblies and the table tops of the lifting tables separately and individually, and then leave the overall assembly process of the lifting tables to the consumer for completion, due to storage, logistics costs and the like.

Of course, the present invention is not limited to the above-described embodiments, and various modifications may be made to the above-described embodiments of the present invention by those skilled in the art in light of the present teachings without departing from the scope of the present invention. For example:

(i) According to the elevating platform of the present invention, the pressure cylinder 50 may not be used to provide the second auxiliary power, i.e., the provision of the pressure cylinder 50 may be omitted. When the pressure cylinder 50 is used to provide the second auxiliary power, a normal pressure cylinder having the cylinder inner diameter equal in the axial direction may also be used.

(ii) The lifting platform according to the invention may have only one (but not two) leg 20, in which case the synchronous lifting device 40 connected to the leg 20 acts to transmit the rotation of the central shaft 33.

(iii) Instead of a planetary gear arrangement, the transmission 32 may be provided with a common gear arrangement, for example, in which the transmission 32 is provided with a large gear and a small gear, the rotation axes of which are not collinear, in which case the torsion spring 31 is connected to the large gear as the input member and the central shaft 33 is connected to the small gear as the output member. Although the common speed changer may occupy more space than the planetary gear speed changer, the common speed changer has low precision requirement on parts, more flexible gear ratio setting and convenient maintenance.

(iv) The drive chain 42 may also be an endless drive member of other forms such as a belt, a rope, etc.

Claims

1. A lifting platform comprises a platform surface, an energy conversion device (30) connected below the platform surface and a leg assembly, and is characterized in that,

the energy conversion device (30) is used for converting elastic potential energy into auxiliary energy for lifting the table top, and comprises a torsion spring (31), a center shaft (33) and a speed changer (32), wherein the torsion spring (31) is sleeved on the periphery of the center shaft (33), the first end of the torsion spring (31) is connected to an input part of the speed changer (32), the center shaft (33) is connected to an output part of the speed changer (32), the rotating speed of the input part is smaller than that of the output part,

the leg assembly is connected with the central shaft (33), and the leg assembly shortens or lengthens to enable the table top to descend or ascend in the process of forward rotation or reverse rotation of the central shaft (33),

the transmission (32) is a planetary gear transmission and comprises a gear ring (324), a sun gear (322), a plurality of planet gears (323) and a planet carrier (321), wherein the gear ring (324) is fixed, the planet carrier (321) is used as an input part to be connected with the torsion spring (31), the sun gear (322) is used as an output part to be connected with the central shaft (33), the central shaft (33) axially passes through the sun gear (322) and is connected with the sun gear (322) in a non-rotatable manner, the torsion spring (31) and the central shaft (33) are coaxially arranged, or,

the transmission (32) includes a large gear as the input member and a small gear as the output member, the rotational axes of the large gear and the small gear being non-collinear.

2. The lift table according to claim 1, characterized in that it further comprises a cross beam (10) fixed to the table top, the energy conversion device (30) further comprising a clutch (35), a brake fork (36) and a transmission assembly (37);

the clutch (35) is fixed on the cross beam (10), and the middle shaft (33) can pass through the clutch (35) in a rotating way around the self axis;

-said brake fork (36) being fixed to said central shaft (33), said brake fork (36) being selectively lockable or releasable by said clutch (35); when the brake fork (36) is locked by the clutch (35), the middle shaft (33) cannot rotate; when the brake fork (36) is released by the clutch (35), the middle shaft (33) can rotate around the axis of the middle shaft;

the transmission assembly (37) is connected to a second end of the torsion spring (31), the second end of the torsion spring (31) being rotatable relative to the first end by operation of the transmission assembly (37) to cause the torsion spring (31) to accumulate elastic potential energy.

3. The lift table of claim 1, wherein the leg assembly includes a first leg (21), a second leg (22), and a synchronous lift device (40), the first leg (21) being movable toward and away from the second leg (22) along an axial direction of the second leg (22),

the synchronous lifting device (40) comprises:

a support (41) which is long;

two driving wheels arranged at two ends of the supporting frame (41);

a synchronization connector (43) fixed to the endless transmission member; wherein,

the central shaft (33) is connected with the annular transmission part, the supporting frame (41) is fixedly connected to the first leg part (21), and the synchronous connector (43) is fixedly connected to the second leg part (22).

4. A lifting platform according to claim 3, characterized in that the first leg (21) is sleeved on the outer periphery of the second leg (22).

5. The lifting platform according to claim 1, characterized in that the energy conversion device (30) further comprises an outer stub shaft (34), which outer stub shaft (34) is movably nested in the axial direction of each other at the end of the central shaft (33) and the central shaft (33).

6. A lifting platform according to claim 5, characterized in that a spring (341) is provided at the junction of the outer stub shaft (34) and the centre shaft (33), the outer stub shaft (34) being able to be brought close to the centre shaft (33) by pressing the spring (341).

7. A lifting platform according to claim 3, characterized in that the leg assembly further comprises a pressure cylinder (50), a cylinder body (51) of the pressure cylinder (50) being fixedly connected with the support frame (41), a piston rod (52) of the pressure cylinder (50) being fixedly connected with the second leg (22).

8. Elevating platform according to claim 7, characterized in that the piston (53) of the pressure cylinder (50) divides the cylinder (51) into a first chamber (C1) and a second chamber (C2), the first chamber (C1) and the second chamber (C2) being in fluid communication, the piston rod (52) protruding from the second chamber (C2) out of the cylinder (51),

the cylinder (51) is divided into a first region and a second region in the axial direction, the second region is closer to the protruding end of the piston rod (52) than the first region,

in the first region, the inner diameter of the cylinder (51) becomes gradually larger in the direction from the first chamber (C1) to the second chamber (C2), and in the second region, the inner diameter of the cylinder (51) is kept constant in the direction from the first chamber to the second chamber.