Electric push rod

Abstract

The utility model discloses an electric push rod which comprises a motor, a speed reduction assembly, a lead screw and a telescopic assembly, the motor drives the lead screw to rotate through the speed reduction assembly, the telescopic assembly is driven by the lead screw to do linear telescopic motion, and the speed reduction assembly comprises a planetary gear set and a transmission sleeve. The planetary gear set comprises a sun gear driven by a motor, a gear ring used for driving the transmission sleeve, a locked planet carrier and a planet gear rotationally installed on the planet carrier, the lead screw penetrates through the sun gear and can rotate relative to the sun gear, the gear ring drives the lead screw to rotate through the transmission sleeve, and the outer side of the transmission sleeve is sleeved with a self-locking torsional spring. When the lead screw rotates reversely under the action of a load, the transmission sleeve drives the self-locking torsional spring to act so as to brake the lead screw. According to the electric push rod provided by the utility model, the reduction ratio of the speed reduction assembly can be increased, so that the electric push rod meets the use requirement of high thrust output.

Description

TECHNICAL FIELD

[0001] The utility model relates to electric push rod technical field especially electric push rod. BACKGROUND

[0002] The prior art electric push rod comprises a motor, a speed reducer assembly, a screw rod and a telescopic assembly, the motor drives the screw rod to rotate through the speed reducer assembly, the telescopic assembly is driven by the screw rod to make linear telescopic movement, and the high-speed rotation of the motor can be reduced to the required low speed through the speed reducer assembly to adapt to the working requirement of mechanical equipment. The pushing force of the electric push rod depends on the torque of the output end of the speed reducer assembly, the greater the torque is, the greater the pushing force of the electric push rod is, therefore, selecting a speed reducer assembly with a large enough speed reduction ratio can effectively increase the output torque and further increase the pushing force of the push rod.

[0003] The prior art speed reducer assembly comprises a worm and gear structure, the worm is connected with the output shaft of the motor, and the worm wheel is in transmission connection with the screw rod. This power transmission mode only undergoes one-stage speed reduction, and since the worm and gear speed reduction is limited, large torque output cannot be realized. When the electric push rod is applied to a medical bed and linear displacement of a large load, it needs to have a large enough pushing force, therefore, the prior art electric push rod cannot meet the use requirement of large pushing force output. CONTENT OF THE UTILITY MODEL

[0004] The utility model solves the technical problem in the prior art and provides an electric push rod which can increase the speed reduction ratio of the speed reducer assembly to meet the use requirement of large pushing force output.

[0005] To solve the above technical problem, the utility model adopts the following technical scheme:

[0006] The electric push rod comprises a motor, a speed reducer assembly, a screw rod and a telescopic assembly, the motor drives the screw rod to rotate through the speed reducer assembly, the telescopic assembly is driven by the screw rod to make linear telescopic movement, the speed reducer assembly comprises a planetary gear set and a transmission sleeve, the planetary gear set comprises a sun gear driven by the motor, a gear ring for driving the transmission sleeve, a locked planet carrier and a planet wheel rotatably installed on the planet carrier, the screw rod penetrates through the sun gear and can rotate relative to the sun gear, the gear ring drives the screw rod to rotate through the transmission sleeve, a self-locking torsional spring is sleeved outside the transmission sleeve, and the screw rod is reversely rotated under the action of a load, the self-locking torsional spring is driven by the transmission sleeve to expand and contact the self-locking sleeve to be self-locked, and the transmission sleeve drives the self-locking torsional spring to contract to move away from the self-locking sleeve when the gear ring drives the screw rod to rotate.

[0007] In the above electric push rod, the electric push rod further comprises a self-locking sleeve which is sleeved outside the self-locking torsional spring and is circumferentially locked, the screw rod is reversely rotated under the action of a load, the self-locking torsional spring is driven by the transmission sleeve to expand and contact the self-locking sleeve to be self-locked, and the transmission sleeve drives the self-locking torsional spring to contract to move away from the self-locking sleeve when the gear ring drives the screw rod to rotate.

[0008] In the above electric push rod, the transmission sleeve includes an outer transmission sleeve fixed in the circumferential direction relative to the gear ring and an inner transmission sleeve fixed in the circumferential direction relative to the screw rod. When the outer transmission sleeve drives the screw rod to rotate in the positive direction through the inner transmission sleeve, the outer transmission sleeve drives the self-locking torsion spring to contract. When the screw rod reverses under the action of a load and drives the inner transmission sleeve to rotate, the inner transmission sleeve drives the self-locking torsion spring to expand. When the outer transmission sleeve drives the screw rod to reverse through the inner transmission sleeve, the outer transmission sleeve has an idling stroke relative to the inner transmission sleeve and a working stroke to drive the inner transmission sleeve to rotate. When the outer transmission sleeve is in the idling stroke, the outer transmission sleeve drives the self-locking torsion spring to contract.

[0009] In the above electric push rod, the outer transmission sleeve is provided with a plurality of transmission grooves at intervals in the circumferential direction, and the inner transmission sleeve is provided with a transmission block inserted into the transmission grooves. The transmission grooves have a first transmission surface abutting against the transmission block and a second transmission surface having a gap with the transmission block. When the outer transmission sleeve drives the screw rod to rotate in the positive direction and the screw rod reverses under the action of a load, the transmission block abuts against the first transmission surface.

[0010] In the above electric push rod, the self-locking torsion spring includes a first leg and a second leg. The first leg is inserted into the transmission groove and located outside the gap, and the axial projection of the first leg is located within the axial projection of the gap. The second leg is clamped between the side of the transmission block away from the gap and the side wall of the transmission groove. When the screw rod rotates in the positive direction, the second leg is driven to rotate by the outer transmission sleeve to make the self-locking torsion spring contract. When the screw rod reverses under the action of a load, the second leg is driven to rotate by the inner transmission sleeve to make the self-locking torsion spring expand. When the outer transmission sleeve is in the idling stroke, the first leg is driven to make the self-locking torsion spring contract.

[0011] In the above electric push rod, the inner transmission sleeve is provided with a first limiting portion, the outer transmission sleeve is provided with a second limiting portion, and the self-locking torsion spring is axially limited between the first limiting portion and the second limiting portion.

[0012] In the above electric push rod, the planet carrier is connected with a brake sleeve sleeved outside the self-locking sleeve. The brake sleeve is fixed in the circumferential direction relative to the planet carrier. One of the self-locking sleeve and the brake sleeve is provided with a first positioning protrusion, and the other is provided with a first positioning groove. The first positioning protrusion and the first positioning groove are inserted and matched to fix the self-locking sleeve and the brake sleeve in the circumferential direction. Alternatively, the brake sleeve forms the self-locking sleeve.

[0013] In the above electric push rod, the speed reduction assembly further includes a first housing, and the planetary gear set is installed in the first housing. The planet carrier is fixed in the circumferential direction relative to the first housing.

[0014] In the electric push rod, the first housing is internally provided with a brake sleeve fixed relative to the first housing in the circumferential direction, the brake sleeve is sleeved outside the gear ring, one of the brake sleeve and the planet carrier is provided with a second positioning protrusion, and the other is provided with a second positioning groove, and the second positioning protrusion and the second positioning groove are inserted and connected to fix the brake sleeve and the planet carrier relative to each other in the circumferential direction.

[0015] In the electric push rod, the speed reduction assembly further comprises a worm wheel and a worm, the worm wheel is connected with the sun gear and rotates synchronously, and the worm is connected with the output shaft of the motor.

[0016] In the electric push rod, the telescopic assembly comprises an inner tube, an outer tube and a nut, the nut is fixedly arranged in the inner tube and is threadedly connected with the lead screw, when the motor drives the lead screw to rotate in the positive direction through the speed reduction assembly, the nut drives the inner tube to move to elongate the telescopic assembly, and when the lead screw reverses, the nut drives the inner tube to move to shorten the telescopic assembly.

[0017] The electric push rod has the advantages that:

[0018] In the electric push rod, the planet carrier is locked and cannot rotate, the power of the motor is input through the sun gear, transmitted through the planetary gear and then output through the gear ring, the number of teeth of the sun gear is less than that of the planetary gear, one-stage reduction is realized through the transmission of the sun gear and the planetary gear, two-stage reduction is realized through the transmission of the planetary gear and the gear ring, compared with the worm and gear reduction mode in the prior art, one-stage reduction is added, that is, the reduction ratio of the planetary gear set is greater than that of the worm and gear, so that the use requirement of large thrust output can be met; in addition, after the electric push rod drives the lead screw to rotate in the positive direction and pushes the load to a specified height, the motor stops rotating, the lead screw reverses under the action of the gravity of the load, the load descends, the load cannot be stably arranged at a certain height, and the user is easily injured during the descending process of the load, safety is poor; the transmission sleeve outside the transmission sleeve is sleeved with a self-locking torsional spring, when the lead screw reverses under the action of the load, the self-locking torsional spring is driven to act through the transmission sleeve to brake the lead screw, so that the lead screw is prevented from reversing under the action of the load and causing the load to descend, and safety accidents are avoided.

[0019] The characteristics and advantages of the electric push rod will be disclosed in detail in the following specific embodiments and drawings.

DRAWINGS

[0020] The electric push rod will be further described below with reference to the drawings:

[0021] Figure 1 It is a structure schematic view of the electric push rod in the embodiment one of the electric push rod.

[0022] Figure 2 It is an explosion schematic view of the electric push rod in the embodiment one of the electric push rod. Figure 1 ;

[0023] Figure 3 An exploded view of the electric push rod in the first embodiment of the present application Figure 2 ;

[0024] Figure 4 A sectional view of the electric push rod in the first embodiment of the present application

[0025] Figure 5 A partial enlarged view of A in the first embodiment of the present application Figure 4

[0026] A structural view of the planetary gear set in the first embodiment of the present application Figure 6

[0027] A sectional view of the planetary gear set in the first embodiment of the present application Figure 7

[0028] An exploded view of the transmission sleeve in the first embodiment of the present application Figure 8

[0029] An assembly view of the inner transmission sleeve and the outer transmission sleeve in the first embodiment of the present application Figure 9

[0030] An assembly view of the transmission sleeve and the self-locking torsion spring in the first embodiment of the present application Figure 10

[0031] A front view of the structure in the first embodiment of the present application Figure 11 Figure 10 An assembly view of the electric push rod in the first embodiment of the present application

[0032] Figure 12 Reference signs:

[0033] Reference signs:

[0034] ​100, motor; 200, speed reduction assembly; 210, planetary gear set; 211, sun gear; 212, planet gear; 213, planet carrier; 2130, second positioning groove; 214, ring gear; 2140, protrusion; 220, transmission sleeve; 221, outer transmission sleeve; 2210, insertion groove; 2211, transmission groove; 2212, first transmission surface; 2213, second transmission surface; 2214, second limiting portion; 222, inner transmission sleeve; 2221, transmission block; 2222, first limiting portion; 223, gap; 230, first housing; 2301, half housing; 231, brake sleeve; 2310, second positioning protrusion; 240, worm gear; 250, worm; 300, lead screw; 310, bearing; 320, limiting piece; 330, spring; 400, telescopic assembly; 410, inner tube; 420, outer tube; 430, nut; 500, self-locking torsional spring; 510, first pin; 520, second pin; 600, self-locking sleeve; 610, first positioning protrusion. [DETAILED DESCRIPTION]

[0035] The utility model provides an electric push rod, including motor, speed reduction assembly, lead screw and telescopic assembly, the motor passes through speed reduction assembly and drives the rotation of lead screw, and telescopic assembly is driven by lead screw and makes linear telescopic motion, the speed reduction assembly includes planetary gear set and transmission sleeve, and the planetary gear set includes the sun gear of motor drive, the ring gear for driving transmission sleeve, the planet carrier of being locked and the planet gear of rotation installation on planet carrier, and the lead screw passes through sun gear and can rotate relative to sun gear, the ring gear drives the rotation of lead screw through transmission sleeve, the transmission sleeve outside is equipped with self -locking torsional spring, when the lead screw reverses under the action of load, drives self -locking torsional spring action to implement the brake of lead screw through transmission sleeve.

[0036] The planet carrier in the utility model is locked and cannot rotate, the power of motor is input through the sun gear, is output by the ring gear after planetary gear transmission, the number of teeth of sun gear is less than the number of teeth of planet gear by making, can realize one -stage reduction through the transmission of sun gear and planet gear, and then realizes two -stage reduction through the transmission of planet gear and ring gear, compared with the mode of worm gear reduction in the prior art, it has one -stage reduction, that is, the reduction ratio of planetary gear set is greater than the reduction ratio of worm gear, thereby meeting the use demand of large thrust output, in addition, after the electric push rod drives the lead screw and rotates positively and pushes the load to the specified height, the motor stops rotating, the lead screw will reverse under the gravity of load and cause the load to drop, so that the load cannot be stabilized at a certain height, and the load is also easy to hurt the user in the process of dropping, and the safety is poor, the transmission sleeve outside in the utility model is equipped with self -locking torsional spring, the lead screw reverses under the action of load, drives self -locking torsional spring action to implement the brake of lead screw through transmission sleeve, so it can avoid the lead screw from reversing under the action of load and causing the load to drop, thereby avoiding the occurrence of safety accidents.

[0037] The technical solutions of the embodiments of the present invention are explained and illustrated below in conjunction with the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all of them. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without making creative work all fall within the scope of protection of the present invention. In addition, it should be understood that the following words indicating orientation or positional relationship such as "up", "down", "left", "right", "longitudinal", "lateral", "inside", "outside", "vertical", "horizontal", "top", "bottom", etc. are only based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] Example 1

[0039] like Figures 1 to 12 As shown, the electric linear actuator in this embodiment includes a motor 100, a reduction assembly 200, a screw 300, and a telescopic assembly 400. The motor 100 drives the screw 300 to rotate through the reduction assembly 200. The telescopic assembly 400 is driven by the screw 300 to perform linear telescopic motion. The telescopic assembly 400 includes an inner tube 410, an outer tube 420, and a nut 430. The nut 430 is fixed within the inner tube 410 and threadedly connected to the screw 300. The nut 430 is fixed circumferentially and axially relative to the inner tube 410. When the motor 100 drives the screw 300 to rotate forward through the reduction assembly 200, the nut 430 drives the inner tube 410 to move, thereby extending the telescopic assembly 400. When the screw 300 rotates reversely, the nut 430 drives the inner tube 410 to move, thereby shortening the telescopic assembly 400. When the electric linear actuator is used to push a load to move up or down, the load is raised when the screw 300 rotates forward, and lowered when the screw 300 rotates reversely.

[0040] The speed reduction assembly 200 in the embodiment comprises a planetary gear set 210 and a transmission sleeve 220, the planetary gear set 210 comprises a sun gear 211, planet gears 212, a planet carrier 213 and a ring gear 214, the planet gears 212 are rotationally installed on the planet carrier 213, a plurality of planet gears 212 are arranged outside the sun gear 211 and mesh with the sun gear 211, the ring gear 214 is arranged outside the plurality of planet gears 212 and meshes with the planet gears 212, the lead screw 300 in the embodiment comprises a light shaft section and a threaded section, the light shaft section is arranged through the sun gear 211 and rotationally cooperates with the sun gear 211, so that the lead screw 300 can rotate relative to the sun gear 211 and shuttle freely, the threaded section is threadedly connected with the nut 430, the light shaft section and the threaded section are integrally processed and formed or are separately processed and formed and then assembled and fixed, the sun gear 211 is driven to rotate by the motor 100, the planet carrier 213 is locked and cannot rotate, and the ring gear 214 can rotate, so that the power of the motor 100 is input through the sun gear 211, transmitted through the planet gears 212 and then output by the ring gear 214, and the ring gear 214 drives the lead screw 300 to rotate through the transmission sleeve 220.

[0041] The number of teeth of the sun gear 211 in the embodiment is less than the number of teeth of the planet gears 212, so that one-stage speed reduction can be realized through the transmission of the sun gear 211 and the planet gears 212, and two-stage speed reduction can be realized through the transmission of the planet gears 212 and the ring gear 214, that is, the speed reduction ratio of the planetary gear set 210 is greater than the speed reduction ratio of the worm gear, so that the use requirement of large thrust output can be met; in addition, after the electric push rod drives the lead screw 300 to rotate in the positive direction to push the load to a specified height, the motor 100 stops rotating, the lead screw 300 reverses under the action of the gravity of the load, the load descends, the load cannot be stably kept at a certain height, and the user is easily injured during the descending of the load, so that the safety is poor; the transmission sleeve 220 in the embodiment is provided with the self-locking torsional spring 500 outside, when the lead screw 300 reverses under the action of the load, the self-locking torsional spring 500 is driven to act through the transmission sleeve 220 to brake the lead screw 300, so that the lead screw 300 cannot reverse under the action of the load to cause the load to descend, and the occurrence of safety accidents is avoided.

[0042] In order to lock the planet carrier 213, the speed reduction assembly 200 in the embodiment further comprises a first housing 230, the first housing 230 is formed by butting two half housings 2301 and connected by screws, the planetary gear set 210 is installed in the first housing 230, and the planet carrier 213 is fixed in the circumferential direction relative to the first housing 230, so that the planet carrier 213 can be locked and cannot rotate.

[0043] Specifically, as shown in FIG. 6, the first housing 230 is provided with a plurality of first screw holes 231, the planet carrier 213 is provided with a plurality of second screw holes 2131, and the first screw holes 231 and the second screw holes 2131 are arranged in a one-to-one correspondence, so that the planet carrier 213 can be fixed in the circumferential direction relative to the first housing 230 through the first screw holes 231 and the second screw holes 2131. Figures 3 to 6As shown, the first shell 230 is provided with a brake sleeve 231 fixed relative to the circumference of the first shell 230, the outer circumference of the brake sleeve 231 is fixed relative to the inner side wall of the first shell 230 by means of spline cooperation, or the brake sleeve 231 is fixed relative to the first shell 230 by means of screw connection, or the brake sleeve 231 is integrally formed with the first shell 230, in the embodiment, the brake sleeve 231 is sleeved outside the gear ring 214, the planet carrier 213 includes spaced upper supports and lower supports, the edges of the lower supports extend to the outside of the gear ring 214, the planet wheel 212 is rotatably installed between the upper supports and the lower supports by means of a rotating shaft, wherein the lower end of the brake sleeve 231 is provided with a plurality of second positioning protrusions 2310 spaced in the circumference, and the edges of the lower supports are provided with a plurality of second positioning grooves 2130 spaced in the circumference, the second positioning protrusions 2310 and the second positioning grooves 2130 are inserted and matched to fix the brake sleeve 231 and the planet carrier 213 relative to the circumference, so that the planet carrier 213 is locked on the first shell 230 and cannot rotate.

[0044] It can be understood that in other embodiments of the utility model, the second positioning protrusions can also be provided on the lower supports, and the second positioning grooves can also be provided on the brake sleeve.

[0045] It can be understood that in other embodiments of the utility model, the brake sleeve can also be integrally formed with the lower supports, and such design can also fix the brake sleeve and the planet carrier relative to the circumference.

[0046] In order to simplify the structure, the electric push rod in the embodiment further includes a self-locking sleeve 600 fixed relative to the circumference, the self-locking sleeve 600 is sleeved outside the self-locking torsional spring 500, when the screw rod 300 reverses under the action of the load, the self-locking torsional spring 500 is driven to expand and contact the self-locking sleeve 600 through the transmission sleeve 220, so that the frictional resistance between the self-locking torsional spring 500 and the self-locking sleeve 600 can be generated, the frictional resistance can prevent the self-locking torsional spring 500 from rotating relative to the self-locking sleeve 600, and further prevent the transmission sleeve 220 from rotating, thereby preventing the screw rod 300 from continuing to reverse and causing the load to decrease, and realizing the self-locking of the screw rod 300 under the action of the load, when the gear ring 214 drives the screw rod 300 to rotate through the transmission sleeve 220, the self-locking torsional spring 500 is driven to contract to move away from the self-locking sleeve 600, so that the self-locking torsional spring 500 can rotate relative to the self-locking sleeve 600 smoothly, and when the power of the motor 100 is used as a power source to drive the screw rod 300 to rotate forward and reverse, the frictional resistance will not exist between the self-locking torsional spring 500 and the self-locking sleeve 600, thereby reducing the power consumption of the motor 100.

[0047] In order to realize the circumferential locking of the self-locking sleeve 600, the brake sleeve 231 in the embodiment surrounds the outside of the self-locking sleeve 600, the outer circumferential side of the self-locking sleeve 600 is provided with a plurality of first positioning protrusions 610 extending in the axial direction, the inner circumferential side of the brake sleeve 231 is provided with a plurality of first positioning grooves extending in the axial direction, and the first positioning protrusions 610 and the first positioning grooves are inserted and matched to fix the self-locking sleeve 600 and the brake sleeve 231 circumferentially relative. Since the brake sleeve 231 is fixed circumferentially relative to the first shell 230, the self-locking sleeve 600 is also circumferentially locked.

[0048] It can be understood that in other embodiments of the utility model, the first positioning protrusions can also be arranged on the inner side of the brake sleeve and extend in the axial direction, and the first positioning grooves are arranged on the outer circumferential side of the self-locking sleeve and extend in the axial direction.

[0049] It can be understood that in other embodiments of the utility model, the self-locking sleeve is integrally processed with the first shell to realize circumferential locking; or the brake sleeve forms the self-locking sleeve.

[0050] Since the self-locking torsion spring 500 will be in contact with the self-locking sleeve 600 after expansion, and frictional resistance will be generated between the self-locking torsion spring 500 and the self-locking sleeve 600, in order to prolong the service life of the self-locking sleeve 600, the self-locking sleeve 600 in the embodiment is independently processed and formed and is made of wear-resistant material.

[0051] As shown in Figure 5 , Figure 6 , Figures 8 to 12 The transmission sleeve 220 in the embodiment includes an outer transmission sleeve 221 and an inner transmission sleeve 222, wherein the outer transmission sleeve 221 is fixed circumferentially relative to the gear ring 214, that is, the inner circumferential side of the gear ring 214 is circumferentially spaced apart from a plurality of protrusions 2140 extending radially inward, and the outer transmission sleeve 221 is provided with a plurality of insertion grooves 2210 inserted and matched with the protrusions 2140, so that the outer transmission sleeve 221 can be fixed circumferentially relative to the gear ring 214, and the inner transmission sleeve 222 is fixed circumferentially relative to the lead screw 300, that is, the inner transmission sleeve 222 is fixed circumferentially relative to the lead screw 300 through the spline connection.

[0052] It can be understood that in other embodiments of the utility model, the outer transmission sleeve can also be integrally processed with the gear ring; or the inner transmission sleeve is integrally processed with the lead screw.

[0053] When the outer transmission sleeve 221 drives the lead screw 300 to rotate forward through the inner transmission sleeve 222, the outer transmission sleeve 221 drives the self-locking torsion spring 500 to contract, at this time the transmission sleeve 220 will not be subjected to the frictional resistance applied by the self-locking sleeve 600, thereby reducing the power consumption of the motor 100; while the lead screw 300 reverses under the action of the load and drives the inner transmission sleeve 222 to rotate, the inner transmission sleeve 222 drives the self-locking torsion spring 500 to expand, thereby achieving the braking of the lead screw 300, and when the outer transmission sleeve 221 drives the lead screw 300 to reverse through the inner transmission sleeve 222, the outer transmission sleeve 221 has an idle stroke of idling relative to the inner transmission sleeve 222 and a working stroke of driving the inner transmission sleeve 222 to rotate, when the outer transmission sleeve 221 is in the idle stroke, the outer transmission sleeve 221 drives the self-locking torsion spring 500 to contract, so that when the motor 100 drives the lead screw 300 to reverse, the self-locking torsion spring 500 is first caused to contract away from the self-locking sleeve 600 to avoid contact between the two to generate frictional resistance, and then the inner transmission sleeve 222 is driven to rotate to cause the lead screw 300 to reverse to drive the load to descend, thereby the entire descending process will not be subjected to the frictional resistance applied by the self-locking sleeve 600, reducing the power consumption of the motor 100.

[0054] The outer transmission sleeve 221 comprises a plurality of arc-shaped blocks arranged circumferentially and spaced around the axis of the lead screw 300, and a transmission groove 2211 is formed between adjacent two arc-shaped blocks, so that the outer transmission sleeve 221 has a plurality of transmission grooves 2211, the inner transmission sleeve 222 is provided with a transmission block 2221 extending radially outward and inserted into the transmission groove 2211, the arc length of the transmission block 2221 is smaller than the arc length of the transmission groove 2211, the transmission groove 2211 has a first transmission face 2212 and a second transmission face 2213, i.e. the two side faces of the adjacent two arc-shaped blocks opposite in the circumferential direction form the first transmission face 2212 and the second transmission face 2213 respectively, when the telescopic assembly 400 is in the shortest state, the first transmission face 2212 abuts against the transmission block 2221, and a gap 223 is formed between the second transmission face 2213 and the transmission block 2221, the forward rotation direction of the lead screw 300 is the rotation direction of the first transmission face 2212 rotating towards the second transmission face 2213 located on the same transmission groove 2211, so that when the outer transmission sleeve 221 drives the lead screw 300 to rotate forward through the inner transmission sleeve 222 and the lead screw 300 drives the inner transmission sleeve 222 to reverse under the action of the load, the transmission block 2221 always abuts against the first transmission face 2212, while when the outer transmission sleeve 221 drives the lead screw 300 to reverse through the inner transmission sleeve 222, since the second transmission face 2213 has the gap 223 with the transmission block 2221, the outer transmission sleeve 221 is in the idle stroke of idling relative to the inner transmission sleeve 222 before the second transmission face 2213 abuts against the transmission block 2221, and the outer transmission sleeve 221 is in the working stroke of driving the inner transmission sleeve 222 to rotate after the second transmission face 2213 abuts against the transmission block 2221.

[0055] As Figure 9 ,Figure 10 and Figure 11 As shown in the figure, the spiral direction of the self-locking torsion spring 500 in the embodiment is the same as the positive rotation direction of the lead screw 300, which comprises a first pin 510 at the lower end and a second pin 520 at the upper end, the first pin 510 is inserted into the transmission groove 2211 and located outside the gap 223, that is, the first pin 510 is located between the two adjacent arc blocks and below the transmission block 2221, the axial projection of the first pin 510 is located within the axial projection of the gap 223, the second transmission surface 2213 is provided with a notch, the second pin 520 is located in the notch, and the second pin 520 is clamped between the side of the transmission block 2221 away from the gap 223 and the side wall of the transmission groove. In this way, when the lead screw 300 rotates positively, the second pin 520 is driven to rotate positively by the first transmission surface 2212 on the outer transmission sleeve 221 to make the self-locking torsion spring 500 contract, and when the lead screw 300 reverses under the action of the load, the second pin 520 is driven to reverse by the transmission block 2221 on the inner transmission sleeve 222 to make the self-locking torsion spring 500 expand and contact the self-locking sleeve 600, and when the motor 100 drives the lead screw 300 to reverse, the first pin 510 is driven to reverse by the second transmission surface 2213 when the outer transmission sleeve 221 is in the idle stroke to make the self-locking torsion spring 500 contract.

[0056] It can be understood that in other embodiments of the utility model, the spiral direction of the self-locking torsion spring can also be the same as the reverse direction, and the fixing mode of the first pin and the second pin can be adaptively changed, which will not be described in detail here.

[0057] In order to realize the axial limiting of the self-locking torsion spring 500, the outer transmission sleeve 221 in the embodiment further comprises an annular second limiting portion 2214, the arc block is integrally formed on the top surface of the second limiting portion 2214, the insertion groove 2210 is arranged on the second limiting portion 2214, and the inner transmission sleeve 222 is provided with a first limiting portion 2222, that is, the top of at least one transmission block 2221 extends radially outward to form the first limiting portion 2222, and the self-locking torsion spring 500 is axially limited between the first limiting portion 2222 and the second limiting portion 2214. Preferably, one side of the first limiting portion 2222 abuts against the second pin 520 to increase the contact area of the second pin 520 and the transmission block 2221, thereby increasing the installation reliability of the second pin 520.

[0058] In addition, the speed reduction assembly 200 in the embodiment further comprises a worm wheel 240 and a worm 250, the sun gear 211 comprises a meshing section provided with teeth and a connecting section extending axially downward, the worm wheel 240 is connected with the connecting section of the sun gear 211 in a manner of spline connection or interference fit, so that the worm wheel 240 and the sun gear 211 can rotate synchronously, and the worm 250 is connected with the output shaft of the motor 100, so that the power of the motor 100 is transmitted to the sun gear 211 after being reduced by the worm wheel and worm, that is, the output rotating speed of the gear ring 214 is further reduced, the output torque of the speed reduction assembly 200 is improved, that is, the speed reduction ratio of the speed reduction assembly 200 is increased, and the use requirement of large thrust output can be further met.

[0059] Finally, as shown in Figure 5 the spline transmission is provided between the lead screw 300 and the inner transmission sleeve 222, the lead screw 300 is rotationally connected with the sun gear 211 through the bearing 310, the lead screw 300 is axially movable relative to the planetary gear set 210, the lower end of the lead screw 300 is provided with the limiting piece 320 fixed by a screw, the lower end of the lead screw 300 is provided with the spring 330, the lower end of the spring 330 is connected with the limiting piece 320, and the upper end of the spring 330 is connected with the bearing 310. When the inner tube 410 in the telescopic assembly 400 is clamped by an object or a human body during the retraction driven by the motor 100, the lead screw 300 is pulled out because the inner tube 410 cannot be retracted under the driving of the nut 430, at this time, the external spline on the lead screw 300 can be disengaged from the internal spline on the inner transmission sleeve 222, that is, the connection between the lead screw 300 and the speed reduction assembly 200 is disconnected, the lead screw 300 stops rotating, the nut 430 stops moving, and the inner tube 410 stops retracting, so that the anti-pinch effect is realized. When the lead screw 300 is pulled out, the spring 330 is compressed, so when the clamped object or human body is removed, the lead screw 300 can be pulled back because the spring 330 has restoring force after being compressed, so that the external spline on the lead screw 300 is re-engaged with the internal spline on the inner transmission sleeve 222, and the electric push rod resumes normal operation.

[0060] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited to this. Those skilled in the art should understand that the present application includes but is not limited to the contents described in the drawings and the above specific implementation. Any modification not deviating from the function and structural principle of the present application shall be included in the protection scope of the claims.

Claims

1. An electric push rod, comprising a motor, a reduction assembly, a screw and a telescopic assembly, wherein the motor drives the screw to rotate through the reduction assembly, and the telescopic assembly is driven by the screw to perform linear telescopic motion, characterized in that: The speed reduction assembly comprises a planetary gear set and a transmission sleeve, the planetary gear set comprises a sun gear driven by a motor, a ring gear for driving the transmission sleeve, a locked planet carrier and planet gears rotatably mounted on the planet carrier, a lead screw penetrates through the sun gear and is rotatable relative to the sun gear, the ring gear drives the lead screw to rotate through the transmission sleeve, a self-locking torsion spring is sleeved outside the transmission sleeve, when the lead screw reverses under load, the self-locking torsion spring is driven to act through the transmission sleeve to brake the lead screw.

2. The motorized push rod of claim 1, wherein, The electric push rod further comprises a self-locking sleeve sleeved outside the self-locking torsion spring and circumferentially locked, when the lead screw reverses under load, the self-locking torsion spring is driven to expand and contact the self-locking sleeve through the transmission sleeve to be self-locked, when the ring gear drives the lead screw to rotate through the transmission sleeve, the transmission sleeve drives the self-locking torsion spring to contract to move away from the self-locking sleeve.

3. The motorized push rod of claim 2, wherein, The transmission sleeve comprises an outer transmission sleeve fixed circumferentially relative to the ring gear and an inner transmission sleeve fixed circumferentially relative to the lead screw, when the outer transmission sleeve drives the lead screw to rotate through the inner transmission sleeve, the outer transmission sleeve drives the self-locking torsion spring to contract, when the lead screw reverses under load and drives the inner transmission sleeve to rotate, the inner transmission sleeve drives the self-locking torsion spring to expand, when the outer transmission sleeve drives the lead screw to reverse through the inner transmission sleeve, the outer transmission sleeve has an idle stroke of idling relative to the inner transmission sleeve and a working stroke of driving the inner transmission sleeve to rotate, when the outer transmission sleeve is in the idle stroke, the outer transmission sleeve drives the self-locking torsion spring to contract.

4. The motorized push rod of claim 3, wherein, The outer transmission sleeve is circumferentially spaced with a plurality of transmission grooves, the inner transmission sleeve is provided with transmission blocks inserted into the transmission grooves, the transmission grooves have first transmission surfaces abutting the transmission blocks and second transmission surfaces having gaps with the transmission blocks, when the outer transmission sleeve drives the lead screw to rotate through the inner transmission sleeve and the lead screw reverses under load, the transmission blocks abut the first transmission surfaces.

5. The motorized push rod of claim 4, wherein, The self-locking torsion spring comprises first and second pins, the first pin is inserted into the transmission groove and located outside the gap, and an axial projection of the first pin is located within an axial projection of the gap, the second pin is clamped between a side of the transmission block away from the gap and a side wall of the transmission groove, when the lead screw rotates through the outer transmission sleeve to drive the second pin to rotate to make the self-locking torsion spring contract, when the lead screw reverses under load through the inner transmission sleeve to drive the second pin to rotate to make the self-locking torsion spring expand, when the outer transmission sleeve is in the idle stroke, the outer transmission sleeve drives the first pin to make the self-locking torsion spring contract.

6. The motorized push rod of claim 3, wherein, The inner transmission sleeve is provided with a first limiting portion, the outer transmission sleeve has a second limiting portion, and the self-locking torsion spring is axially limited between the first limiting portion and the second limiting portion.

7. The motorized push rod of claim 2, wherein, The planet carrier is connected with a brake sleeve sleeved outside the self-locking sleeve, the brake sleeve is circumferentially fixed relative to the planet carrier, one of the self-locking sleeve and the brake sleeve is provided with a first positioning protrusion, and the other is provided with a first positioning groove, the first positioning protrusion and the first positioning groove are inserted and matched to circumferentially fix the self-locking sleeve and the brake sleeve relative to each other; or, the brake sleeve forms the self-locking sleeve.

8. The electric push rod according to any one of claims 1 to 7, characterized in that The speed reduction assembly further comprises a first housing, the planetary gear set is mounted in the first housing, and the planet carrier is circumferentially fixed relative to the first housing.

9. The motorized push rod of claim 8, wherein, The first shell is internally provided with a brake sleeve fixed relative to the first shell in the circumferential direction, the brake sleeve is sleeved outside the gear ring, one of the brake sleeve and the planet carrier is provided with a second positioning protrusion, and the other is provided with a second positioning groove, the second positioning protrusion and the second positioning groove are inserted and connected to fix the brake sleeve and the planet carrier relative to each other in the circumferential direction.

10. The electric push rod according to any one of claims 1 to 7, wherein The speed reduction assembly further comprises a worm gear and a worm, the worm gear is connected with the sun gear and rotates synchronously, and the worm is connected with the output shaft of the motor.

11. The electric push rod according to any one of claims 1 to 7, wherein The telescopic assembly comprises an inner tube, an outer tube and a nut, the nut is fixedly arranged in the inner tube and is threadedly connected with the lead screw, when the motor drives the lead screw to rotate in the positive direction through the speed reduction assembly, the nut drives the inner tube to move so that the telescopic assembly is elongated, and when the lead screw is reversed, the nut drives the inner tube to move so that the telescopic assembly is shortened.

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