CN116730245A - Screw assembly, linear actuating device and lifting device - Google Patents
Screw assembly, linear actuating device and lifting device Download PDFInfo
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- CN116730245A CN116730245A CN202311018770.4A CN202311018770A CN116730245A CN 116730245 A CN116730245 A CN 116730245A CN 202311018770 A CN202311018770 A CN 202311018770A CN 116730245 A CN116730245 A CN 116730245A
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- nut
- screw
- safety
- safety nut
- circumferential surface
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- 230000007246 mechanism Effects 0.000 claims abstract description 53
- 230000005540 biological transmission Effects 0.000 claims description 12
- 230000009471 action Effects 0.000 claims description 5
- 230000000717 retained effect Effects 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 description 8
- 230000007257 malfunction Effects 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
- B66F7/10—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported directly by jacks
- B66F7/12—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported directly by jacks by mechanical jacks
- B66F7/14—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported directly by jacks by mechanical jacks screw operated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F13/00—Common constructional features or accessories
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F17/00—Safety devices, e.g. for limiting or indicating lifting force
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
- B66F7/02—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms suspended from ropes, cables, or chains or screws and movable along pillars
- B66F7/025—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms suspended from ropes, cables, or chains or screws and movable along pillars screw operated
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mechanical Engineering (AREA)
- Structural Engineering (AREA)
- Transmission Devices (AREA)
Abstract
The application provides a screw assembly, a linear actuating device and lifting equipment. The screw assembly includes a center screw, a main nut engaged with the center screw to convert rotational movement of the center screw into translational movement, and a safety nut engaged with the center screw when the main nut fails, wherein the screw assembly further includes a clutch mechanism disposed between the main nut and the safety nut, the clutch mechanism being configured such that the safety nut is engaged with the main nut to move the main nut when the center screw is rotated in one direction, and the safety nut is disengaged from the main nut to not move the main nut when the center screw is rotated in a direction opposite to the one direction. The screw rod assembly is simple in structure, low in cost and high in reliability.
Description
Technical Field
The present application relates to a screw assembly, and a linear actuation device and a lifting device comprising such a screw assembly.
Background
Lifting devices such as operating tables, aerial platforms, cranes or scissor lifts, etc., typically employ linear actuators to drive the corresponding load bearing platform. The linear actuation device generally includes an electric motor, a transmission mechanism such as a gear box, and a screw assembly connected to a rotating shaft of the electric motor through the transmission mechanism. The lead screw assembly includes a center screw, a main nut engaged with the center screw to convert rotational movement of the center screw into translational movement, and a safety nut engaged with the center screw in the event of failure of the main nut.
The safety nut is not in contact with the central screw when the main nut is operating normally, but engages and carries the load under the load (in the present application "load" may include the load carrying platform and the people and things thereon) once the screw of the main nut fails due to abnormal wear or material imperfections, the balls between the main nut and the central screw come off or other faults cause the main nut to fail to operate normally. Because the friction force between the safety nut and the central screw rod is larger, the effect of clamping the central screw rod can be achieved. When the safety nut is engaged with the center screw, this indicates that the screw assembly has failed or is damaged. In this case, for example, in the case of an aerial platform, if the push tube of the screw assembly is extended outwards with respect to the protective tube and the load is lifted by the screw assembly, this may create serious safety hazards; in the case of a lifting frame for car repair, for example, the screw assembly can likewise present serious safety hazards if the push tube of the screw assembly is retracted inwards relative to the protective tube. Since the driving power efficiency of the linear actuator is remarkably deteriorated when the safety nut is engaged with the center screw, an electronic control system has been proposed which monitors the change in the driving power efficiency of the linear actuator by a controller to determine whether the linear actuator is malfunctioning, and when it is determined that the malfunction is occurring, controls the operation of the motor such that the push tube of the screw assembly can only be lowered but cannot be raised. The electronic control system for controlling the movement of the push tube based on the operation of the control motor is complex in structure, high in cost and low in reliability, and the safety risk existing in the operation process of the linear actuating device cannot be completely eliminated.
Accordingly, there is a need for improvements in existing lead screw assemblies for linear actuation devices.
Disclosure of Invention
The object of the present application is to overcome the above-mentioned drawbacks of the prior art and to provide a screw assembly, and a linear actuator and a lifting device comprising such a screw assembly, which can ensure, by means of a mechanical structure, that the screw assembly can only extend or retract the push tube outwards or inwards with respect to the protective tube in case of failure of the main nut and not functioning properly.
According to an aspect of the present application, there is provided a screw assembly comprising:
a central screw;
a main nut engaged with the central screw to convert rotational movement of the central screw into translational movement; and
a safety nut engaged with the central screw upon failure of the main nut;
wherein the screw assembly further comprises a clutch mechanism disposed between the main nut and the safety nut, the clutch mechanism being configured such that the safety nut is coupled to the main nut to move when the center screw is rotated in one direction, and the safety nut is uncoupled from the main nut to not move when the center screw is rotated in a direction opposite to the one direction.
Preferably, the clutch mechanism is disposed radially between the main nut and the safety nut.
Preferably, the lead screw assembly further comprises a tail cap disposed around the central screw, the tail cap being fixedly connected to the main nut so as to define a space with the main nut for holding the safety nut.
Preferably, a receiving cavity is formed at one end of the main nut, the safety nut being partially retained in the receiving cavity.
Preferably, a receiving cavity is formed at one end of the main nut, the safety nut being disposed entirely in the receiving cavity and being held in the receiving cavity by a bearing disposed radially between the safety nut and the main nut.
Preferably, the lead screw assembly further comprises a spring member arranged to bear against the safety nut to urge the safety nut axially onto the main nut.
Preferably, the lead screw assembly further comprises a plurality of balls disposed between axially opposed surfaces of the main nut and the safety nut.
Preferably, the clutch mechanism includes:
a plurality of wedge grooves formed circumferentially spaced apart on an outer circumferential surface of the safety nut, the wedge grooves having a flat bottom surface; and
a roller disposed in each of the wedge grooves;
wherein the safety nut and the tail cap are locked together by the roller when the center screw is rotated in the one direction, and are disengaged when the center screw is rotated in a direction opposite to the one direction.
Preferably, the clutch mechanism includes:
a plurality of wedge grooves formed circumferentially spaced apart on an outer circumferential surface of the safety nut, the wedge grooves having a flat bottom surface; and
a roller disposed in each of the wedge grooves;
wherein the safety nut and the main nut are locked together by the roller when the center screw is rotated in the one direction, and are disengaged when the center screw is rotated in the opposite direction.
Preferably, an axial groove is formed on the bottom surface near an end of the wedge groove having a larger depth, in which a torsion spring is provided, one end of which abuts against the roller and the other end abuts against a wall of the wedge groove.
Preferably, the clutch mechanism includes:
a plurality of mounting grooves formed on an outer circumferential surface of the safety nut at a circumferential interval;
the free ends of the pawls extend out of the outer circumferential surface under the action of the elastic sheets; and
a plurality of inclined pawl receiving grooves formed circumferentially spaced apart on an inner circumferential surface of the tail cap;
wherein the pawl is engaged with the pawl receiving slot when the central screw is rotated in the one direction and the pawl is disengaged from the pawl receiving slot when the central screw is rotated in a direction opposite to the one direction.
Preferably, the clutch mechanism includes:
a plurality of mounting grooves formed on an outer circumferential surface of the safety nut at a circumferential interval;
the free ends of the pawls extend out of the outer circumferential surface under the action of the elastic sheets; and
a plurality of inclined pawl receiving grooves formed circumferentially spaced apart on an inner circumferential surface of the main nut;
wherein the pawl is engaged with the pawl receiving slot when the central screw is rotated in the one direction and the pawl is disengaged from the pawl receiving slot when the central screw is rotated in a direction opposite to the one direction.
Preferably, the clutch mechanism includes:
a plurality of camming wedges circumferentially spaced apart between an outer circumferential surface of the safety nut and an inner circumferential surface of the tail cap, a major diameter of the camming wedges being greater than a spacing between the outer circumferential surface of the safety nut and the inner circumferential surface of the tail cap, a minor diameter of the camming wedges being less than the spacing; and
the spiral springs are arranged on the supporting point of each cam wedge block so as to reset the cam wedge blocks;
wherein the safety nut and the tail cap are locked together by the camming wedge when the central screw is rotated in the one direction, and the safety nut is disengaged from the tail cap when the central screw is rotated in a direction opposite to the one direction.
Preferably, the clutch mechanism includes:
a plurality of camming wedges circumferentially spaced apart between an outer circumferential surface of the safety nut and an inner circumferential surface of the main nut, a major diameter of the camming wedges being greater than a spacing between the outer circumferential surface of the safety nut and the inner circumferential surface of the main nut, a minor diameter of the camming wedges being less than the spacing; and
the spiral springs are arranged on the supporting point of each cam wedge block so as to reset the cam wedge blocks;
wherein the safety nut and the main nut are locked together by the camming wedge when the central screw is rotated in the one direction, and the safety nut is disengaged from the main nut when the central screw is rotated in the opposite direction.
Preferably, an annular groove for receiving the camming wedge is formed on the outer circumferential surface of the safety nut.
According to another aspect of the present application, there is provided a linear actuation device comprising:
a motor;
a lead screw assembly as described above; and
and the transmission mechanism is used for connecting the rotating shaft of the motor with the central screw rod of the screw rod assembly.
Preferably, the linear actuation device further comprises an electromagnetic brake having a release handle, the electromagnetic brake being arranged to brake the motor when de-energized.
According to a further aspect of the application there is provided a lifting device, wherein the lifting device comprises a screw assembly as described above or a linear actuation means as described above.
According to the application, in the event of failure of the main nut, when the central screw rotates in the one direction, the safety nut and the main nut are locked together by the clutch mechanism to drive the main nut and the push tube to move, so as to retract the push tube or extend the push tube relative to the protection tube; when the central screw rod rotates along the direction opposite to the one direction, the safety nut and the main nut are separated, the safety nut is turned in situ, the main nut and the push tube are not driven to move, and the push tube and the load are kept in place relative to the protection tube. Therefore, the screw assembly according to the present application completely uses a mechanical structure to control the movement of the main nut and the push tube without requiring a complex electronic control system, and thus has a simple structure, low cost, and high reliability, thereby minimizing or eliminating the safety risk existing during the operation of the linear actuator.
In order to more clearly illustrate the structural features and efficacy of the present application, the present application will be described in detail below with reference to the accompanying drawings and examples.
Drawings
FIG. 1 is a cross-sectional view schematically showing a linear actuator of the present application;
fig. 2 is a cross-sectional view schematically showing a screw assembly according to a first preferred embodiment of the present application;
FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2;
FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 2;
FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 2;
FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 2;
FIG. 7 is a cross-sectional view schematically showing a lead screw assembly according to a second preferred embodiment of the present application;
FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 7;
FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 7;
FIG. 10 is a cross-sectional view taken along line 10-10 of FIG. 7;
FIG. 11 is a cross-sectional view taken along line 11-11 of FIG. 7;
FIG. 12 is a cross-sectional view schematically showing a lead screw assembly according to a third preferred embodiment of the present application;
FIG. 13 is a cross-sectional view taken along line 13-13 of FIG. 12;
FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. 12;
FIG. 15 is a cross-sectional view taken along line 15-15 of FIG. 12;
FIG. 16 is a cross-sectional view taken along line 16-16 of FIG. 12; and
fig. 17 is a sectional view schematically showing a screw assembly according to a fourth preferred embodiment of the present application.
Detailed Description
Specific embodiments of the application will be described in detail below with reference to the drawings, but it should be understood that the drawings are for illustration only and are not to be construed as limiting the application.
Fig. 1 is a sectional view schematically showing a linear actuator of the present application. As shown in fig. 1, the linear actuation device 1 generally includes an electric motor 3 for providing power, a transmission mechanism 5 such as a gear box, belt transmission, chain transmission, and a screw assembly 7 connected to a rotating shaft of the electric motor 3 through the transmission mechanism 5. The screw assembly 7 includes a central screw 9, a main nut 11 engaged with the central screw 9 to convert rotational movement of the central screw 9 into translational movement, and a safety nut 13 engaged with the central screw 9 when the main nut 11 fails. The screw assembly 7 may further comprise a push tube 15 arranged around the central screw 9, the push tube 15 being rigidly connected at a proximal end to the main nut 11 and provided at a distal end with a rotatable joint 17 for rotatably connecting the push tube 15 to a carrying platform (not shown). The lead screw assembly 7 may further comprise a shield tube 19 disposed around the central screw 9, the main nut 11, the safety nut 13 and the push tube 15, the proximal end of the shield tube 19 being fixed to the transmission mechanism 5, the distal end of the shield tube 19 being provided with an opening 21, the opening 21 being configured to slidably receive the push tube 15.
Upon forward rotation of the motor 3, the transmission mechanism 5, which is connected to the rotation shaft of the motor 3 and the center screw 9 of the screw assembly 7, respectively, transmits the rotational movement of the rotation shaft of the motor 3 to the center screw 9 at a reduced rotation speed, and the main nut 11, which is engaged with the center screw 9, converts the rotational movement of the center screw 9 into a translational movement, thereby pushing the push tube 15 to protrude outward with respect to the shield tube 19 to push or raise the load far. Upon reverse rotation of the motor 3, the main nut 11 brings the push tube 15 to retract inwardly relative to the shield tube 19 to retract or lower the load.
The linear actuation device 1 may further comprise an electromagnetic brake 25 with a release handle 23, the electromagnetic brake 25 being arranged in a braking state in the de-energized state for braking the motor in case of a sudden de-energizing of the motor 3, thereby preventing the rotation of the central screw 9, so that the push tube 15 is prevented from retracting into the protective tube 19 under external pressure in case of a de-energizing or other malfunction. When it is desired to retract the push tube 15 to lower the load, the operator can release the braking state of the electromagnetic brake 25 by pulling the release handle 23 due to the power failure, so that the push tube 15 is retracted into the protective tube 19 under the load. In a preferred embodiment, an electromagnetic brake 25 is provided at the end of the motor 3 opposite to the connection with the transmission 5 for braking the rotation shaft of the motor 3 in case of a power failure or other malfunction.
Although the screw composed of the center screw 9 and the main nut 11 may be a trapezoidal screw, a ball screw or a roller screw is more practically used due to a lower transmission efficiency of the trapezoidal screw. When the trapezoidal screw is in failure of threads of the main nut due to abnormal abrasion or material defects, balls between the main nut and the central screw of the ball screw fall off, rollers between the main nut and the central screw of the roller screw fall off or other faults cause the main nut to work abnormally, the safety nut is engaged with the central screw under the action of load and bears the load. According to the application, the screw assembly 7 further comprises a clutch mechanism 29 arranged between the main nut 11 and the safety nut 13, the clutch mechanism 29 being configured such that the safety nut 13 is coupled to the main nut 11 to move together when the central screw 9 is rotated in one direction, and such that the safety nut 13 is uncoupled from the main nut 11 to not move together when the central screw 9 is rotated in the opposite direction. Thus, in case that the main nut 11 fails and cannot work normally, when the central screw 9 rotates in one direction, the safety nut 13 is combined with the main nut 11 to drive the main nut 11 and thus the push tube 15 to move together, so as to retract the push tube 15 or extend the push tube 15 relative to the protection tube 19; when the central screw 9 is rotated in the opposite direction to this one direction, the safety nut 13 is disengaged from the main nut 11, the safety nut 13 idles with respect to the main nut 11 and does not bring the main nut 11 and the push tube 15 together, the push tube 15 and the load remaining in place with respect to the protection tube 19.
Fig. 2 is a sectional view schematically showing a lead screw assembly of a first preferred embodiment of the present application, fig. 3 is a sectional view taken along line 3-3 of fig. 2, fig. 4 is a sectional view taken along line 4-4 of fig. 2, fig. 5 is a sectional view taken along line 5-5 of fig. 2, and fig. 6 is a sectional view taken along line 6-6 of fig. 2. As shown in fig. 2, a receiving cavity 31 is formed at the proximal end of the main nut 11 (i.e., remote from the end connected to the push tube 15) for at least partially receiving the safety nut 13 disposed around the central screw 9. The tail cap 33, which is arranged around the central screw 9, is fixedly connected to the main nut 11 by means of a connecting means 35, such as a screw, in order to hold the safety nut 13 in a space 37 defined by the main nut 11 and the tail cap 33. A disc spring 39 may be provided between the tail cap 33 and the safety nut 13 to urge the safety nut 13 axially against the main nut 11. The disc spring may be replaced with a wave spring, and the type of the spring member is not limited as long as the safety nut can be axially pressed against the main nut. Preferably, a plurality of balls 41 may be provided between axially opposed surfaces of the main nut 11 and the safety nut 13 to facilitate smooth rotation of the safety nut 13 relative to the main nut 11. As shown in fig. 2-6, according to a first preferred embodiment of the present application, the clutch mechanism 29 includes a plurality of wedge grooves 45 formed circumferentially spaced apart on the outer circumferential surface 43 of the safety nut 13, the wedge grooves 45 having a generally flat bottom surface 47 so as to have a progressively varying radial depth along the circumferential direction. The clutch mechanism 29 further includes a roller 49 disposed in each wedge groove 45.
The safety nut 13 engages the central screw 9 in the event of failure of the main nut 11. Due to the high friction between the safety nut 13 and the central screw 9, when the motor 3 drives the central screw 9 to rotate in one direction, the safety nut 13 tends to rotate in the clockwise direction in fig. 3-6, and the rollers 49 lock with the safety nut 13 and the tail cap 33 to cause the tail cap 33 to rotate in the clockwise direction. Since the tail cap 33 is connected with the main nut 11 by the connecting means 35, the main nut 11 and the push tube 15 are eventually moved together, allowing the push tube 15 to be retracted or extended with respect to the protective tube 19. When the motor 3 drives the central screw 9 to rotate in the other direction, the safety nut 13 has a tendency to rotate in a counter-clockwise direction in fig. 3-6, and the roller 49 is disengaged from the safety nut 13 and the tail cap 33. Under the pretension of the disc spring 39, the safety nut 13 is turned in place by means of the balls 41. Thus, the main nut 11 and the push tube 15 will not move, and the push tube 15 and the load will remain in place relative to the shield tube 19. Thus, after the safety nut 13 has been engaged with the central screw 9, only the main nut 11 can be driven in one way by means of the clutch mechanism 29.
An axial groove 51 may be formed on the bottom surface 47 at the end of the wedge groove 45 having a greater depth, and a torsion spring 53 is provided in the axial groove 51, one end of the torsion spring 53 abutting the roller 49 and the other end abutting the wall of the wedge groove 45. In this way, the position of the roller 49 in the wedge groove 45 can be restricted, so that the response speed of the clutch mechanism 29 when switching from the disengaged state to the locked state can be improved.
Fig. 7 is a sectional view schematically showing a screw assembly according to a second preferred embodiment of the present application, fig. 8 is a sectional view taken along line 8-8 of fig. 7, fig. 9 is a sectional view taken along line 9-9 of fig. 7, fig. 10 is a sectional view taken along line 10-10 of fig. 7, and fig. 11 is a sectional view taken along line 11-11 of fig. 7. For brevity, descriptions of the same elements of the second preferred embodiment of the present application as those of the first preferred embodiment of the present application will be omitted below.
As shown in fig. 7 to 11, according to the second preferred embodiment of the present application, the clutch mechanism 29 includes a plurality of mounting grooves 55 formed on the outer circumferential surface 43 of the safety nut 13 at intervals in the circumferential direction, each of the mounting grooves 55 having a pawl 57 provided therein, and a free end of the pawl 57 protruding beyond the outer circumferential surface 43 of the safety nut 13 by a spring piece, not shown. The clutch mechanism 29 further includes a plurality of inclined pawl receiving grooves 59 formed circumferentially spaced apart on the inner circumferential surface of the tail cap 33 such that the tail cap 33 is formed as an inner ratchet.
When the safety nut 13 has a tendency to rotate in a clockwise direction in fig. 8-11, the pawl 57 on the safety nut 13 engages the pawl receiving slot 59 on the inner circumferential surface of the tail cap 33 to lock together, ultimately moving the main nut 11 and push tube 15 together, allowing the push tube 15 to retract or extend relative to the protective tube 19. When the safety nut 13 has a tendency to rotate in a counterclockwise direction in fig. 8-11, the pawl 57 on the safety nut 13 disengages from the pawl receiving groove 59 on the inner circumferential surface of the tail cap 33. Under the pretension of the disc spring 39, the safety nut 13 is turned in place by means of the balls 41. Thus, the main nut 11 and the push tube 15 will not move, and the push tube 15 and the load will remain in place relative to the shield tube 19. Thus, after the safety nut 13 has been engaged with the central screw 9, only the main nut 11 can be driven in one way by means of the clutch mechanism 29.
Fig. 12 is a sectional view schematically showing a lead screw assembly according to a third preferred embodiment of the present application, fig. 13 is a sectional view taken along line 13-13 of fig. 12, fig. 14 is a sectional view taken along line 14-14 of fig. 12, fig. 15 is a sectional view taken along line 15-15 of fig. 12, and fig. 16 is a sectional view taken along line 16-16 of fig. 12. For brevity, descriptions of the elements of the third preferred embodiment of the present application that are identical to the elements of the first preferred embodiment of the present application will be omitted.
As shown in fig. 12 to 16, according to the third preferred embodiment of the present application, the clutch mechanism 29 includes a plurality of camming wedges 61 that are disposed circumferentially spaced between the outer circumferential surface 43 of the safety nut 13 and the inner circumferential surface of the tail cap 33. Each camming wedge 61 has two diameters of different sizes, wherein the longer diameter is greater than the spacing between the outer circumferential surface 43 of the safety nut 13 and the inner circumferential surface of the tail cap 33 and the shorter diameter is less than the spacing between the outer circumferential surface 43 of the safety nut 13 and the inner circumferential surface of the tail cap 33. A coil spring 63, which is connected end to form a ring shape, is provided on the fulcrum of each cam wedge 61 so as to restore the cam wedge 61. In a preferred embodiment, an annular groove 64 may be formed on the outer circumferential surface 43 of the safety nut 13 for receiving the plurality of camming wedges 61. Furthermore, in the preferred embodiment, two rings of camming wedges 61 are provided between the outer circumferential surface 43 of the safety nut 13 and the inner circumferential surface of the tail cap 33, it being understood that only one ring of camming wedges 61 or more rings of camming wedges 61 may be provided.
When the safety nut 13 has a tendency to rotate in a clockwise direction in fig. 13-16, since the long diameter of the camming wedge 61 is greater than the spacing between the outer circumferential surface 43 of the safety nut 13 and the inner circumferential surface of the tail cap 33, the camming wedge 61 is captured between the tail cap 33 and the safety nut 13 such that the safety nut 13 and the tail cap 33 are locked together, ultimately moving the main nut 11 and the push tube 15 together, allowing the push tube 15 to retract or extend relative to the protective tube 19. When the safety nut 13 has a tendency to rotate in a counterclockwise direction in fig. 13-16, the cam wedge 61 is not caught between the tail cap 33 and the safety nut 13, and the safety nut 13 is separated from the tail cap 33 because the minor diameter of the cam wedge 61 is smaller than the distance between the outer circumferential surface 43 of the safety nut 13 and the inner circumferential surface of the tail cap 33. Under the pretension of the disc spring 39, the safety nut 13 is turned in place by means of the balls 41. Thus, the main nut 11 and the push tube 15 will not move, and the push tube 15 and the load will remain in place relative to the shield tube 19. Thus, after the safety nut 13 has been engaged with the central screw 9, only the main nut 11 can be driven in one way by means of the clutch mechanism 29.
In the preferred embodiments described above, the clutch mechanism 29 is arranged to move the tail cap 33 with the main nut 11 in a clockwise direction of rotation in figures 3-6, 8-11 and 13-16, it being understood that the clutch mechanism 29 may be arranged to move the tail cap 33 with the main nut 11 in a counter-clockwise direction of rotation in these figures as desired.
In the first to third preferred embodiments, the safety nut 13 is only partially disposed in the receiving cavity 31 at the proximal end of the main nut 11, but it should be understood that the safety nut 13 may be disposed entirely in the receiving cavity 31 at the proximal end of the main nut 11. Fig. 17 is a sectional view schematically showing a screw assembly according to a fourth preferred embodiment of the present application. The fourth preferred embodiment is substantially identical to the first preferred embodiment except that the safety nut 13 is disposed entirely within the receiving cavity 31 at the proximal end of the main nut 11, and that a bearing 65, such as a deep groove ball bearing, is disposed radially between the safety nut 13 and the main nut 11 at the open end of the receiving cavity 31. The bearing 65 prevents the safety nut 13 from falling off when the linear actuator is arranged vertically on the one hand, and allows the safety nut 13 and the main nut 11 to be rotated at different times on the other hand. Of course, the clutch structure in the fourth preferred embodiment may be replaced with the clutch structures of the second and third preferred embodiments. It will be appreciated that the tail caps in the second and third preferred embodiments may also be replaced by bearings. Furthermore, it is also possible that no receiving cavity 31 is formed at the proximal end of the main nut 11, in which case the safety nut 13 is substantially held in the receiving cavity formed by the cup-shaped tail cap.
In the fourth preferred embodiment, the clutch mechanism 29 is disposed radially directly between the safety nut 13 and the main nut 11. In the first to third preferred embodiments, the clutch mechanism 29 is disposed radially directly between the safety nut 11 and the tail cap 33, and since the tail cap 33 is coupled to the main nut 11, the clutch mechanism 29 can also be understood as being disposed between the safety nut 13 and the main nut 11. Thus, in the present application, the clutch mechanism 29 radially disposed between the safety nut 13 and the main nut 11 is understood to include the case where the clutch mechanism is disposed directly between the safety nut 13 and the main nut 11 and the case where the clutch mechanism is disposed indirectly between the safety nut 13 and the main nut 11. Furthermore, although in the preferred embodiment the clutch mechanism 29 is disposed radially between the safety nut 13 and the main nut 11, it should also be appreciated that the clutch mechanism 29 may be disposed axially between the safety nut 13 and the main nut 11, such as may be disposed between axially opposed surfaces of the main nut 11 and the safety nut 13. In the latter case, the constituent elements of the clutch 29 can be adapted. Thus, in the present application, the clutch mechanism 29 provided between the safety nut 13 and the main nut 11 is understood to include a case where the clutch mechanism is provided radially between the safety nut 13 and the main nut 11 and a case where the clutch mechanism is provided axially between the safety nut 13 and the main nut 11.
The foregoing describes preferred embodiments of the application, but the spirit and scope of the application is not limited to the specific embodiments disclosed herein. Those skilled in the art can make numerous modifications and substitutions in light of the teachings of the present application which are within the spirit and scope of the present application. The spirit and scope of the present application are not limited by the specific embodiments, but by the appended claims.
Claims (18)
1. A lead screw assembly, comprising:
a central screw (9);
a main nut (11) engaged with the central screw (9) to convert a rotational movement of the central screw (9) into a translational movement; and
a safety nut (13) engaged with the central screw (9) in the event of failure of the main nut (11);
wherein the screw assembly further comprises a clutch mechanism (29) arranged between the main nut (11) and the safety nut (13), the clutch mechanism (29) being configured such that when the central screw (9) rotates in one direction, the safety nut (13) is combined with the main nut (11) to drive the main nut (11) to move, and when the central screw (9) rotates in a direction opposite to the one direction, the safety nut (13) is disengaged from the main nut (11) without driving the main nut (11) to move.
2. A screw assembly according to claim 1, wherein the clutch mechanism (29) is arranged radially between the main nut (11) and the safety nut (13).
3. A screw assembly according to claim 2, further comprising a tail cap (33) arranged around the central screw (9), the tail cap (33) being fixedly connected to the main nut (11) so as to define with the main nut (11) a space (37) for holding the safety nut (13).
4. A screw assembly according to claim 3, wherein a receiving cavity (31) is formed at one end of the main nut (11), the safety nut (13) being partially retained in the receiving cavity (31).
5. A screw assembly according to claim 2, wherein a receiving cavity (31) is formed at one end of the main nut (11), the safety nut (13) being arranged entirely in the receiving cavity (31) and being held in the receiving cavity (31) by means of a bearing (65) arranged radially between the safety nut (13) and the main nut (11).
6. A screw assembly according to claim 3 or 5, further comprising a spring member (39) arranged to abut the safety nut (13) to urge the safety nut (13) axially onto the main nut (11).
7. A screw assembly according to claim 3 or 5, further comprising a plurality of balls (41) arranged between axially opposite surfaces of the main nut (11) and the safety nut (13).
8. A screw assembly according to claim 3, wherein the clutch mechanism (29) comprises:
-a plurality of wedge grooves (45) formed circumferentially spaced apart on an outer circumferential surface (43) of the safety nut (13), the wedge grooves (45) having a flat bottom surface (47); and
a roller (49) disposed in each of said wedge grooves (45);
wherein the safety nut (13) and the tail cap (33) are locked together by the roller (49) when the center screw (9) rotates in the one direction, and the safety nut (13) and the tail cap (33) are disengaged when the center screw (9) rotates in the opposite direction to the one direction.
9. The screw assembly of claim 5, wherein the clutch mechanism (29) comprises:
-a plurality of wedge grooves (45) formed circumferentially spaced apart on an outer circumferential surface (43) of the safety nut (13), the wedge grooves (45) having a flat bottom surface (47); and
a roller (49) disposed in each of said wedge grooves (45);
wherein the safety nut (13) and the main nut (11) are locked together by the roller (49) when the central screw (9) rotates in the one direction, and the safety nut (13) and the main nut (11) are disengaged when the central screw (9) rotates in the opposite direction to the one direction.
10. Screw assembly according to claim 8 or 9, wherein an axial groove (51) is formed on the bottom surface (47) near the end of the wedge groove (45) having a greater depth, a torsion spring (53) being provided in the axial groove (51), one end of the torsion spring (53) abutting the roller (49) and the other end abutting the wall of the wedge groove (45).
11. A screw assembly according to claim 3, wherein the clutch mechanism (29) comprises:
a plurality of mounting grooves (55) formed on an outer circumferential surface (43) of the safety nut (13) at intervals in the circumferential direction;
a pawl (57) provided in each of the mounting grooves (55), the free end of the pawl (57) protruding beyond the outer circumferential surface (43) under the action of a spring piece; and
a plurality of inclined pawl receiving grooves (59) formed on an inner circumferential surface of the tail cap (33) at a circumferential interval;
wherein the pawl (57) is engaged with the pawl receiving groove (59) when the center screw (9) rotates in the one direction, and the pawl (57) is disengaged from the pawl receiving groove (59) when the center screw (9) rotates in a direction opposite to the one direction.
12. The screw assembly of claim 5, wherein the clutch mechanism (29) comprises:
a plurality of mounting grooves (55) formed on an outer circumferential surface (43) of the safety nut (13) at intervals in the circumferential direction;
a pawl (57) provided in each of the mounting grooves (55), the free end of the pawl (57) protruding beyond the outer circumferential surface (43) under the action of a spring piece; and
a plurality of inclined pawl receiving grooves (59) formed on an inner circumferential surface of the main nut (11) at a circumferential interval;
wherein the pawl (57) is engaged with the pawl receiving groove (59) when the center screw (9) rotates in the one direction, and the pawl (57) is disengaged from the pawl receiving groove (59) when the center screw (9) rotates in a direction opposite to the one direction.
13. A screw assembly according to claim 3, wherein the clutch mechanism (29) comprises:
a plurality of cam wedges (61) disposed between an outer circumferential surface (43) of the safety nut (13) and an inner circumferential surface of the tail cap (33) at intervals along a circumferential direction, a long diameter of the cam wedges (61) being larger than a distance between the outer circumferential surface (43) of the safety nut (13) and the inner circumferential surface of the tail cap (33), a short diameter of the cam wedges (61) being smaller than the distance; and
-coil springs (63) connected end to form a ring, said coil springs (63) being arranged on the fulcrum of each of said camming wedges (61) to return said camming wedges (61);
wherein the safety nut (13) and the tail cap (33) are locked together by the camming wedge (61) when the central screw (9) is rotated in the one direction, the safety nut (13) being disengaged from the tail cap (33) when the central screw (9) is rotated in the opposite direction to the one direction.
14. The screw assembly of claim 5, wherein the clutch mechanism (29) comprises:
a plurality of cam wedges (61) disposed between an outer circumferential surface (43) of the safety nut (13) and an inner circumferential surface of the main nut (11) at intervals along a circumferential direction, a long diameter of the cam wedges (61) being larger than a distance between the outer circumferential surface (43) of the safety nut (13) and the inner circumferential surface of the main nut (11), a short diameter of the cam wedges (61) being smaller than the distance; and
-coil springs (63) connected end to form a ring, said coil springs (63) being arranged on the fulcrum of each of said camming wedges (61) to return said camming wedges (61);
wherein the safety nut (13) and the main nut (11) are locked together by the camming wedge (61) when the central screw (9) is rotated in the one direction, the safety nut (13) being disengaged from the main nut (11) when the central screw (9) is rotated in the opposite direction to the one direction.
15. Screw assembly according to claim 13 or 14, wherein an annular groove (64) for receiving the camming wedge (61) is formed on the outer circumferential surface (43) of the safety nut (13).
16. A linear actuation device comprising:
a motor (3);
a screw assembly as claimed in any one of claims 1 to 15; and
and a transmission mechanism (5) for connecting the rotation shaft of the motor (3) with the central screw (9) of the screw assembly (7).
17. Linear actuation device according to claim 16, wherein the linear actuation device further comprises an electromagnetic brake (25) with a release handle (23), the electromagnetic brake (25) being arranged to brake the motor (3) when de-energized.
18. A lifting device, wherein the lifting device comprises a screw assembly according to any one of claims 1-15 or a linear actuation device according to claim 16 or 17.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311018770.4A CN116730245B (en) | 2023-08-14 | 2023-08-14 | Screw assembly, linear actuating device and lifting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311018770.4A CN116730245B (en) | 2023-08-14 | 2023-08-14 | Screw assembly, linear actuating device and lifting device |
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| Publication Number | Publication Date |
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| CN116730245A true CN116730245A (en) | 2023-09-12 |
| CN116730245B CN116730245B (en) | 2023-11-21 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202311018770.4A Active CN116730245B (en) | 2023-08-14 | 2023-08-14 | Screw assembly, linear actuating device and lifting device |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1045638A (en) * | 1989-03-17 | 1990-09-26 | 蒋小钢 | A kind of screw mechanism |
| CN113187866A (en) * | 2021-05-26 | 2021-07-30 | 江苏恒立液压股份有限公司 | Electric cylinder with controllable power-loss fall-back speed |
| CN215974776U (en) * | 2021-09-22 | 2022-03-08 | 济南泰成科技有限公司 | Lifting device and car lifting jack using same |
| CN216112858U (en) * | 2021-03-24 | 2022-03-22 | 中科晶源微电子技术（北京）有限公司 | Lifting device, positioning equipment and chamber equipment |
| CN115259008A (en) * | 2022-07-13 | 2022-11-01 | 中国空气动力研究与发展中心高速空气动力研究所 | Screw lift with telescopic and rotary lead screw |
| CN115523272A (en) * | 2022-09-24 | 2022-12-27 | 浙江鼎力机械股份有限公司 | Linear driver with contact type safety nut and aerial work platform |
-
2023
- 2023-08-14 CN CN202311018770.4A patent/CN116730245B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1045638A (en) * | 1989-03-17 | 1990-09-26 | 蒋小钢 | A kind of screw mechanism |
| CN216112858U (en) * | 2021-03-24 | 2022-03-22 | 中科晶源微电子技术（北京）有限公司 | Lifting device, positioning equipment and chamber equipment |
| CN113187866A (en) * | 2021-05-26 | 2021-07-30 | 江苏恒立液压股份有限公司 | Electric cylinder with controllable power-loss fall-back speed |
| CN215974776U (en) * | 2021-09-22 | 2022-03-08 | 济南泰成科技有限公司 | Lifting device and car lifting jack using same |
| CN115259008A (en) * | 2022-07-13 | 2022-11-01 | 中国空气动力研究与发展中心高速空气动力研究所 | Screw lift with telescopic and rotary lead screw |
| CN115523272A (en) * | 2022-09-24 | 2022-12-27 | 浙江鼎力机械股份有限公司 | Linear driver with contact type safety nut and aerial work platform |
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| Publication number | Publication date |
|---|---|
| CN116730245B (en) | 2023-11-21 |
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