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 lead screw is driven by power transmitted by the speed reduction assembly to rotate, and the telescopic assembly is driven by the lead screw to do linear telescopic motion. The speed reduction assembly comprises a planetary gear set, the planetary gear set comprises a sun gear driven by a motor, a gear ring used for driving a lead screw to rotate, a planet carrier rotationally arranged in the first shell and a planet gear rotationally installed on the planet carrier, and the lead screw penetrates through the sun gear and can rotate relative to the sun gear. The planet carrier is connected with a brake sleeve fixed relative to the planet carrier in the circumferential direction. The electric push rod further comprises a torsional spring brake, the torsional spring brake has a release state for releasing circumferential braking of the braking sleeve and a locking state for implementing circumferential braking on the braking sleeve in a normal state, when the torsional spring brake is in the locking state, the planet carrier is locked in the circumferential direction, and when the torsional spring brake is in the release state, the planet carrier can rotate freely. The electric push rod provided by the utility model can meet the use requirement of high thrust output.

Description

TECHNICAL FIELD

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

[0002] The electric push rod in prior art includes motor, reduction assembly, screw rod and telescopic assembly, motor drives screw rod rotation by reduction assembly, telescopic assembly is driven by screw rod and makes linear telescopic motion, the high-speed rotation of motor can be reduced to the low speed required by reduction assembly, to adapt to the work demand of mechanical equipment.The pushing force of electric push rod depends on the torque of reduction assembly output end, and the pushing force of electric push rod is also greater when torque is greater, so enough large reduction ratio of reduction assembly can effectively increase the torque output, and then increase the pushing force of push rod.

[0003] The existing reduction assembly includes worm gear structure, worm is connected with the output shaft of motor, worm gear is drivingly connected with screw rod, this power transmission mode only passes through one stage reduction, since worm gear reduction is limited, so large torque output cannot be realized, when electric push rod is applied to medical bed and linear displacement of large load, it needs to have enough large pushing force, so the existing electric push rod cannot meet the use demand of large pushing force output. CONTENT OF UTILITY MODEL

[0004] The technical problem to be solved by the utility model is to overcome the prior art deficiencies and provide an electric push rod, which can increase the reduction ratio of reduction assembly, so that the electric push rod meets the use demand of large pushing force output.

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

[0006] An electric push rod, comprising:

[0007] Motor and reduction assembly; and,

[0008] Screw rod and telescopic assembly, the screw rod is driven to rotate by the power transmitted by reduction assembly, and the telescopic assembly is driven by the screw rod to make linear telescopic motion.

[0009] The reduction assembly includes planetary gear set, the planetary gear set includes sun gear driven by motor, gear ring for driving screw rod to rotate, planet carrier rotatingly arranged in first housing and planet wheel rotatingly installed on planet carrier, the screw rod penetrates sun gear and can rotate relative to sun gear, and the planet carrier is connected with brake sleeve fixed relative to its circumferential direction.

[0010] The electric push rod further comprises a torsion spring brake having a release state for releasing the circumferential brake of the brake sleeve and a normal state for locking the brake sleeve, when the torsion spring brake is in the normal state, the planet carrier is circumferentially locked, when the torsion spring brake is in the release state, the planet carrier can rotate freely.

[0011] In the electric push rod, the reduction assembly further comprises a first housing for accommodating the planetary gear set, the torsion spring brake comprises a release device and a brake torsion spring for normally clamping the brake sleeve, the brake torsion spring comprises a first pin and a second pin fixed on the first housing, the release device is used to pull the first pin to release the brake sleeve of the brake torsion spring to release the circumferential brake of the brake sleeve.

[0012] In the electric push rod, the release device comprises a release plate slidingly installed on the first housing, the release plate is connected with the first pin, and driving the release plate to move to pull the first pin to rotate in the loosening direction of the brake torsion spring can release the brake sleeve of the brake torsion spring.

[0013] In the electric push rod, the release device further comprises a release pull rod, the release plate is provided with a guide groove extending along the screw shaft and inclinedly arranged, the release pull rod is provided with a transmission pin inserted into the guide groove and slidingly matched with the guide groove, and pulling the release pull rod to move towards one end of the screw shaft to drive the release plate to move to release the brake sleeve of the brake torsion spring.

[0014] In the electric push rod, the release plate is provided with a connecting hole, and the first pin is inserted into the connecting hole.

[0015] In the electric push rod, the gear ring drives the screw shaft to rotate through the transmission sleeve, the transmission sleeve is provided on the outside with a self-locking torsion spring, the electric push rod further comprises a self-locking sleeve provided on the outside of the self-locking torsion spring and circumferentially fixed with the brake sleeve, when the gear ring drives the screw shaft 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, and when the screw shaft reverses under the action of the load, the transmission sleeve drives the self-locking torsion spring to expand to contact the self-locking sleeve to brake the screw shaft.

[0016] In the electric push rod, the transmission sleeve comprises an outer transmission sleeve circumferentially fixed relative to the gear ring and an inner transmission sleeve circumferentially fixed relative to the screw shaft, when the outer transmission sleeve drives the screw shaft 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 shaft reverses under the action of the 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 shaft to reverse through the inner transmission sleeve, the outer transmission sleeve has an idling 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 idling stroke, the outer transmission sleeve drives the self-locking torsion spring to contract.

[0017] In the electric push rod, the outer transmission sleeve is circumferentially spaced apart from a plurality of transmission grooves, the inner transmission sleeve is provided with a transmission block inserted into the transmission groove, the transmission groove has a first transmission surface abutting against the transmission block and a second transmission surface having a gap with the transmission block, and the outer transmission sleeve is driven by the inner transmission sleeve to rotate the screw in a positive direction and to reverse the screw under the action of a load.

[0018] In the electric push rod, the self-locking torsion spring includes a third pin inserted into the transmission groove and located outside the gap, and an axial projection of the third pin is located within an axial projection of the gap, and a fourth pin is clamped between a side of the transmission block away from the gap and a side wall of the transmission groove, the fourth pin is driven to rotate by the outer transmission sleeve to contract the self-locking torsion spring when the screw rotates in the positive direction, the fourth pin is driven to rotate by the inner transmission sleeve to expand the self-locking torsion spring when the screw reverses under the action of the load, and the third pin is driven to contract the self-locking torsion spring when the outer transmission sleeve is in an idle stroke.

[0019] In the electric push rod, the speed reduction assembly further includes a worm wheel and a worm, the worm wheel is connected with the sun gear and rotates synchronously, the worm is connected with the output shaft of the motor, and the screw is braked by the worm gear self-locking when the screw reverses under the action of the load.

[0020] The electric push rod has the advantages that:

[0021] When the electric push rod drives the screw to rotate in the positive direction to elongate the telescopic assembly, the brake sleeve is in the circumferential braking state of the torsion spring brake, and the brake sleeve is circumferentially fixed relative to the planet carrier, so that the planet carrier is circumferentially locked by circumferential braking of the brake sleeve, that is, the planet carrier cannot rotate, the power of the motor is input through the sun gear, transmitted through the planet gear, and output through the gear ring, the number of teeth of the sun gear is less than that of the planet gear, one-stage reduction is realized through transmission of the sun gear and the planet gear, two-stage reduction is realized through transmission of the planet gear and the gear ring, and the reduction ratio of the planetary gear set is greater than that of the worm gear, so that the use requirement of large thrust output is met.

[0022] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

Brief Description of the Drawings

[0023] The present invention will be further described below with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic structural diagram of the electric push rod in the first embodiment of the present utility model;

[0025] Figure 2 Schematic diagram of the explosion of the electric push rod in the first embodiment of the present utility model Figure 1 ;

[0026] Figure 3 Schematic diagram of the explosion of the electric push rod in the first embodiment of the present utility model Figure 2 ;

[0027] Figure 4 This is a cross-sectional view of the electric push rod in the first embodiment of the present utility model;

[0028] Figure 5 for Figure 4 A partial enlarged schematic diagram;

[0029] Figure 6 This is a schematic structural diagram of a planetary gear set in the first embodiment of the present invention;

[0030] Figure 7 This is a cross-sectional view of the planetary gear set in the first embodiment of the present invention;

[0031] Figure 8 This is a schematic diagram of the internal structure of the electric push rod in Example 1 of the present utility model;

[0032] Figure 9 This is a structural diagram of the brake torsion spring in the first embodiment of the present invention when it is tightly holding the brake sleeve;

[0033] Figure 10 for Figure 9 The main view;

[0034] Figure 11 for Figure 10 Cross-sectional view of the middle BB;

[0035] Figure 12 This is a schematic structural diagram of the brake torsion spring in the first embodiment of the present invention when the brake sleeve is released;

[0036] Figure 13 for Figure 12 The main view;

[0037] Figure 14 for Figure 13 Cross-sectional view of CC;

[0038] Figure 15 It is an explosion schematic view of the transmission sleeve in the embodiment one of the utility model;

[0039] Figure 16 It is an assembly schematic view of the inner transmission sleeve and the outer transmission sleeve in the embodiment one of the utility model;

[0040] Figure 17 It is an assembly schematic view of the transmission sleeve and the self-locking torsional spring in the embodiment one of the utility model;

[0041] Figure 18 It is Figure 10 The main view of the structure in the embodiment one of the utility model;

[0042] Figure 19 It is the assembly schematic view of the electric push rod part structure in the embodiment one of the utility model.

[0043] Reference signs:

[0044] 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 slot; 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 shell; 2301, half shell; 231, brake sleeve; 2310, second positioning protrusion; 232, mounting plate; 2321, limiting groove; 233, positioning pin; 240, worm gear; 250, worm; 300, lead screw; 310, bearing; 320, limiting sheet; 330, spring; 400, telescopic assembly; 410, inner tube; 420, outer tube; 430, nut; 500, self-locking torsional spring; 510, third pin; 520, fourth pin; 600, self-locking sleeve; 610, first positioning protrusion; 700, torsional spring brake; 710, release device; 711, release plate; 7110, guide slot; 7111, connecting hole; 712, release pull rod; 7120, transmission pin; 720, brake torsional spring; 721, first pin; 722, second pin.

DETAILED DESCRIPTION

[0045] The utility model provides a kind of electric push rod, comprising:

[0046] Motor and speed reduction assembly;And,

[0047] Lead screw and telescopic assembly, the lead screw is rotated by the power transmission of speed reduction assembly, and telescopic assembly is driven by lead screw and makes linear telescopic motion;

[0048] The speed reduction assembly comprises a planetary gear set, the planetary gear set comprising a sun gear driven by the motor, a ring gear for driving the screw rod to rotate, a carrier rotatingly arranged in the first housing and a plurality of planet gears rotatingly mounted on the carrier, the screw rod penetrating through the sun gear and being capable of rotating relative to the sun gear, the carrier being connected with a brake sleeve fixed relative to the carrier in the circumferential direction;

[0049] The electric push rod further comprises a torsion spring brake, the torsion spring brake having a release state for releasing the circumferential braking of the brake sleeve and a locking state for implementing the circumferential braking of the brake sleeve in the normal state, the carrier being circumferentially locked when the torsion spring brake is in the locking state, and the carrier being capable of freely rotating when the torsion spring brake is in the release state.

[0050] In the electric push rod, when the screw rod is driven to rotate forward to elongate the telescopic assembly, the brake sleeve is in the state of being circumferentially braked by the torsion spring brake, and the brake sleeve is fixed relative to the carrier in the circumferential direction, so that the carrier is circumferentially locked by the circumferential braking of the brake sleeve, i.e., the carrier cannot rotate, the power of the motor is input through the sun gear, transmitted through the planet gears and output through the ring gear, the number of teeth of the sun gear is less than that of the planet gears, so that one-stage speed reduction is realized through the transmission between the sun gear and the planet gears, and two-stage speed reduction is realized through the transmission between the planet gears and the ring gear, compared with the worm and gear speed reduction mode in the prior art, one-stage speed reduction is added, i.e., the speed 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, when the motor drives the screw rod to rotate reversely to shorten the telescopic assembly, the energy consumption and required time are relatively large, in order to reduce the energy consumption of the motor and shorten the time, the torsion spring brake can be in the release state to release the circumferential braking of the brake sleeve, so that the carrier can freely rotate, in this case, the planetary gear set does not transmit power, so that the screw rod can be rapidly reversed through the action of the load or the pressing of the screw rod to rapidly shorten the telescopic assembly, the rapid release function is realized, the motor is not required to be driven, and the electric push rod is also applicable to the case of motor failure or power failure or other cases requiring to cut off power.

[0051] 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.

[0052] Example 1

[0053] like Figures 1 to 4 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.

[0054] like Figures 5 to 7As shown, the reduction assembly 200 in this embodiment includes a planetary gear set 210, which includes a sun gear 211, planetary gears 212, a planetary carrier 213 and a ring gear 214. The planetary gears 212 are rotatably mounted on the planetary carrier 213. A plurality of planetary gears 212 surround the outer side of the sun gear 211 and mesh with the sun gear 211. The number of teeth of the sun gear 211 is less than the number of teeth of the planetary gears 212. The ring gear 214 surrounds the outer side of the plurality of planetary gears 212 and meshes with the planetary gears 212. The screw rod 300 in this embodiment includes The optical axis section and the threaded section are provided, and the optical axis section passes through the sun gear 211 and rotates with the sun gear 211 so that the screw rod 300 can rotate and shuttle freely relative to the sun gear 211. The threaded section is threadedly connected to the nut 430. The optical axis section and the threaded section are integrally processed and formed or the two are separately processed and formed and then assembled and fixed. The sun gear 211 is driven to rotate by the motor 100, and the planetary carrier 213 is connected to the brake sleeve 231, which is arranged on the outside of the ring gear 214. The brake sleeve 231 is relatively fixed to the planetary carrier 213 in the circumferential direction.

[0055] like Figures 3 to 14 As shown, the electric push rod also includes a torsion spring brake 700, which has a release state for releasing the circumferential braking of the brake sleeve 231 and a locked state for applying circumferential braking to the brake sleeve 231 under normal conditions. When the torsion spring brake 700 is in the locked state, the planetary carrier 213 is circumferentially locked. When the torsion spring brake 700 is in the released state, the planetary carrier 213 can rotate freely.

[0056] The electric push rod in the embodiment drives the screw rod 300 to rotate forward to extend the telescopic assembly 400, at this time, the brake sleeve 231 is in the circumferential braking state of the torsional spring brake 700, and the brake sleeve 231 is circumferentially fixed relative to the planet carrier 213, so that the circumferential locking of the planet carrier 213 can be realized by circumferential braking of the brake sleeve 231, that is, the planet carrier 213 cannot rotate, and the power of the motor 100 is input through the sun gear 211, transmitted through the planet gear 212, and then output by the gear ring 214 to drive the screw rod 300 to rotate. By making the number of teeth of the sun gear 211 less than the number of teeth of the planet gear 212, one-stage reduction can be realized through the transmission of the sun gear 211 and the planet gear 212, and two-stage reduction can be realized through the transmission of the planet gear 212 and the gear ring 214. Compared with the worm and gear reduction mode in the prior art, one more stage of reduction is added, that is, the reduction ratio of the planetary gear set 210 is greater than that of the worm and gear, so that the use requirement of large thrust output can be met. In addition, when the motor 100 drives the screw rod 300 to rotate reversely to shorten the telescopic assembly 400, the energy consumption and the required time are relatively large, in order to reduce the energy consumption of the motor 100 and shorten the time, the torsional spring brake 700 can be in a released state in the embodiment to release the circumferential braking of the brake sleeve 231, so that the planet carrier 213 can rotate freely. In this case, the planet gear set 210 will not transmit power, so that the screw rod 300 can be quickly reversed by the action of the load or the pressing of the screw rod 300 to make the telescopic assembly 400 quickly retract, thereby realizing the quick release function without the need of driving of the motor 100, and also applicable to the case of motor 100 failure or power failure or other cases requiring cutting off of power. Of course, the quick release function can also be used for quick extension of the telescopic assembly 400.

[0057] The reduction assembly 200 in the embodiment further includes a first housing 230, the first housing 230 is formed by two half housings 2301 which are butted and connected by screws, the planetary gear set 210 is installed in the first housing 230, and the planet carrier 213 is rotatably installed in the first housing 230 by a bearing to make the planet carrier 213 rotate in the first housing 230. In order to realize the circumferential relative fixing of the planet carrier 213 and the brake sleeve 231, the planet carrier 213 in the embodiment includes spaced upper and lower supports, and the planet gear 212 is rotatably installed between the upper and lower supports by a rotating shaft. The edge of the lower support extends to the outside of the gear ring 214, wherein the lower end of the brake sleeve 231 protrudes a plurality of second positioning protrusions 2310 which are circumferentially spaced, and the edge of the lower support is provided with a plurality of second positioning grooves 2130 which are circumferentially spaced. The second positioning protrusions 2310 and the second positioning grooves 2130 are inserted and matched to circumferentially fix the brake sleeve 231 and the planet carrier 213 relative to each other.

[0058] It can be understood that in other embodiments of the utility model, the second positioning protrusion can also be arranged on the lower support, and the second positioning groove can also be arranged on the brake sleeve.

[0059] It can be understood that in other embodiments of the utility model, the brake sleeve can also be integrally machined with the lower support, and such design can also enable the brake sleeve to be fixed relative to the planet carrier in the circumferential direction.

[0060] The torsional spring brake 700 in the embodiment comprises a release device 710 and a brake torsional spring 720, wherein the brake torsional spring 720 is normally clamped outside the brake sleeve 231, the brake torsional spring 720 comprises a first pin 721 and a second pin 722 fixed on the first housing 230, and the release device 710 is used to pull the first pin 721 to expand the brake torsional spring 720, thereby releasing the brake sleeve 231, achieving the release of the brake sleeve 231, and thus the brake sleeve 231 can rotate relative to the planet carrier 213 in the circumferential direction, thereby achieving the quick release function, and the structure is relatively simple.

[0061] As shown in Figure 3 , Figures 8 to 11 , for the convenience of the following description, the direction in which the telescopic assembly 400 is located is upward, and the direction in which the speed reduction assembly 200 is located is downward, the release device 710 comprises a release plate 711, two mounting plates 232 are circumferentially arranged on the outer side of the first housing 230, both of the mounting plates 232 extend along the axis of the lead screw 300, each of the mounting plates 232 is provided with a limiting groove 2321 which is closed at the lower end and open at the upper end, the limiting groove 2321 penetrates through the mounting plate 232 along the thickness direction of the mounting plate 232, the release plate 711 is located on the outer side of the first housing 230, and both ends of the release plate 711 are respectively in sliding fit with the two limiting grooves 2321, so that the release plate 711 can slide relative to the first housing 230, and the two mounting plates 232 are further embedded with a positioning pin 233, the positioning pin 233 is located between the release plate 711 and the slot of the limiting groove 2321, so as to prevent the end of the release plate 711 from being pulled out of the limiting groove 2321, and the release plate 711 in the embodiment is a flat plate, so its sliding path is a straight line. The first housing 230 is provided with a through hole through which the first pin 721 penetrates, the release plate 711 is connected with the first pin 721, the first pin 721 has a first position and a second position, when the first pin 721 is at the first position (as shown in Figures 8 to 11 , the brake torsional spring 720 clamps the brake sleeve 231, at this time the torsional spring brake 700 is in the locked state; when the first pin 721 is at the second position (as shown in Figures 12 to 14As shown in the figure), the brake torsion spring 720 releases the brake sleeve 231, at this time the torsion spring brake 700 is in the released state. By driving the release plate 711 to pull the first pin 721 to rotate in the direction of loosening the brake torsion spring 720, that is, to rotate in the direction of the second position, the brake torsion spring 720 can release the brake sleeve 231.

[0062] In order to facilitate the user to operate the release device 710, the release device 710 in the embodiment further includes a release pull rod 712, which extends along the axis of the screw rod 300 in the direction of the telescopic assembly 400, the lower end of the release pull rod 712 is connected with the release plate 711, the release plate 711 is provided with a guide groove 7110, which is an inclined groove extending along the axis of the screw rod 300 and is inclinedly arranged, the release pull rod 712 is provided with a transmission pin 7120 inserted into the guide groove 7110 and slidably matched with the guide groove 7110, when the transmission pin 7120 is matched with the lower end of the guide groove 7110, the first pin 721 is in the first position, at this time the upper end of the guide groove 7110 extends in the direction relative to the second position, the brake torsion spring 720 in the embodiment is left-handed, so the first position is located on the left side of the second position, and correspondingly the upper end of the guide groove 7110 extends leftward. When quick release is needed, the user can drive the release plate 711 to move rightward by pulling the release pull rod 712 upward through the traction rod or traction rope, so as to rotate the first pin 721 in the direction of loosening the brake torsion spring 720, thereby releasing the brake sleeve 231 (as shown in the figure), and further releasing the screw rod 300, the release speed of the screw rod 300 depends on the displacement amount of the release pull rod 712. Figures 12 to 14 When the telescopic assembly 400 is quickly retracted, the release pull rod 712 is loosened, at this time the first pin 721 is reset to the first position under the restoring force of the brake torsion spring 720, so that the brake torsion spring 720 regrasps the brake sleeve 231 to implement circumferential braking on the brake sleeve 231.

[0063] In order to facilitate the connection of the release plate 711 and the first pin 721, the release plate 711 in the embodiment is provided with a connecting hole 7111, and the first pin 721 is inserted into the connecting hole 7111.

[0064] It can be understood that in other embodiments of the utility model, the release pull rod can be omitted, and the brake torsion spring can also release the brake sleeve by directly driving the release plate to move; or the release pull rod and the release plate can be omitted, and the brake torsion spring can also release the brake sleeve by directly moving the first pin with hands.

[0065] It can be understood that in other embodiments of the utility model, the release plate can also be slidably arranged outside the first shell along the circumference of the brake torsion spring, and the sliding path is an arc line.

[0066] It can be understood that in other embodiments of the utility model, when the spiral direction of the brake torsion spring is opposite, those skilled in the art can easily think of how to adaptively change the inclination direction of the guide groove according to the above-mentioned scheme, and will not be described in detail here.

[0067] It should be noted that the brake sleeve 231 in the embodiment is only released from the circumferential brake when rapid release is required, so under normal load support conditions, the torsion spring brake 700 is in a locked state to circumferentially brake the brake sleeve 231.

[0068] As shown in Figure 3 , Figure 5 , Figure 6 , Figures 15 to 19 , after the electric push rod driving screw 300 is rotated in the forward direction to push the load to a specified height, the motor 100 stops rotating, and the screw 300 will be reversed under the action of the gravity of the load, causing the load to drop, so that the load cannot be stabilized at a certain height, and the user is also easily injured during the load drop process, and the safety is poor. In order to solve the technical problem, the gear ring 214 in the embodiment drives the screw 300 to rotate through the transmission sleeve 220, the transmission sleeve 220 is sleeved with the self-locking torsion spring 500 on the outside, and the electric push rod further comprises a self-locking sleeve 600, which is sleeved on the outside of the self-locking torsion spring 500 and is circumferentially fixed relative to the brake sleeve 231. When the gear ring 214 drives the screw 300 to rotate through the transmission sleeve 220, the transmission sleeve 220 drives the self-locking torsion spring 500 to contract to move away from the self-locking sleeve 600, so that the self-locking torsion spring 500 can rotate smoothly relative to the self-locking sleeve 600. Therefore, when the motor 100 drives the screw 300 to rotate in the forward direction and reverse direction as a power source, there will be no frictional resistance between the self-locking torsion spring 500 and the self-locking sleeve 600, thereby reducing the power consumption of the motor 100. When the screw 300 is reversed under the action of the load, the brake sleeve 231 and the self-locking sleeve 600 are circumferentially locked, so that the self-locking torsion spring 500 is driven by the transmission sleeve 220 to expand and contact the self-locking sleeve 600. In this way, frictional resistance can be generated between the self-locking torsion spring 500 and the self-locking sleeve 600, which can prevent the self-locking torsion spring 500 from rotating relative to the self-locking sleeve 600, thereby preventing the transmission sleeve 220 from rotating, thereby achieving the brake of the screw 300. In this way, the screw 300 can be prevented from being reversed under the action of the load, thereby avoiding the occurrence of safety accidents.

[0069] In order to realize the circumferential relative fixation of the self-locking sleeve 600 and the brake sleeve 231, the brake sleeve 231 in the embodiment is surrounded on 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 thereof, and the inner circumferential side of the brake sleeve 231 is provided with a plurality of first positioning grooves extending in the axial direction thereof, 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 to each other.

[0070] It can be understood that in other embodiments of the utility model, the first positioning protrusion can also be arranged on the inner side of the brake sleeve and extend along the axial direction thereof, and the first positioning groove is arranged on the outer circumferential side of the self-locking sleeve and extends along the axial direction thereof.

[0071] It can be understood that in other embodiments of the utility model, the brake sleeve forms the self-locking sleeve, that is, the brake sleeve and the self-locking sleeve are integrally machined and formed.

[0072] Since the self-locking torsion spring 500 is expanded outward and contacts the self-locking sleeve 600, and frictional resistance is 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 machined and formed and is made of wear-resistant material.

[0073] 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 in the circumferential direction 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, 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 in the circumferential direction relative to the gear ring 214, and the inner transmission sleeve 222 is fixed in the circumferential direction relative to the lead screw 300, that is, the inner transmission sleeve 222 is connected with the lead screw 300 through the spline to be fixed in the circumferential direction.

[0074] It can be understood that in other embodiments of the utility model, the insertion groove can also be arranged on the gear ring, and the protrusion is arranged on the outer transmission sleeve; or the outer transmission sleeve can also be integrally machined and formed with the gear ring; or the inner transmission sleeve can also be integrally machined and formed with the lead screw.

[0075] When the outer transmission sleeve 221 drives the lead screw 300 to rotate forward in this embodiment, 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 motor 100 needs to drive the lead screw 300 to reverse, at this time the brake sleeve 231 is tightly held by the brake torsion spring 720 and is circumferentially braked, thereby enabling the outer transmission sleeve 221 to drive the lead screw 300 to reverse through the inner transmission sleeve 222, in this process, the outer transmission sleeve 221 has an idling 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 idling stroke, the outer transmission sleeve 221 drives the self-locking torsion spring 500 to contract, thus when the motor 100 drives the lead screw 300 to reverse, the self-locking torsion spring 500 can be first contracted away from the self-locking sleeve 600 to avoid the contact between the two to generate frictional resistance, i.e. to release the self-locking of the self-locking torsion spring 500, and then the inner transmission sleeve 222 is driven to rotate to make the lead screw 300 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.

[0076] The outer transmission sleeve 221 comprises a plurality of arc blocks arranged circumferentially and spaced around the axis of the screw 300, and a transmission groove 2211 is formed between two adjacent arc 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 less than that 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 circumferentially opposite side faces of two adjacent arc blocks 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 positive rotation direction of the screw 300 is the rotation direction of the first transmission face 2212 when the first transmission face 2212 rotates towards the second transmission face 2213 on the same transmission groove 2211. Thus, when the outer transmission sleeve 221 drives the screw 300 to rotate positively through the inner transmission sleeve 222, and the screw 300 drives the inner transmission sleeve 222 to rotate reversely under the action of a load, the transmission block 2221 always abuts against the first transmission face 2212. When the outer transmission sleeve 221 drives the screw 300 to rotate reversely 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 an idling stroke of idling relative to the inner transmission sleeve 222 before the second transmission face 2213 abuts against the transmission block 2221. When the second transmission face 2213 abuts against the transmission block 2221, the outer transmission sleeve 221 is in a working stroke of driving the inner transmission sleeve 222 to rotate.

[0077] As Figure 17 , Figure 18 and Figure 19As shown, the spiral direction of the self-locking torsion spring 500 in the embodiment is the same as the forward rotation direction of the screw rod 300, which comprises a third pin 510 at the lower end and a fourth pin 520 at the upper end, the third pin 510 is inserted into the transmission groove 2211 and located outside the gap 223, i.e. the third pin 510 is located between the two adjacent arc blocks and below the transmission block 2221, the third pin 510 is axially projected within the axial projection of the gap 223, the second transmission surface 2213 is provided with a notch, the fourth pin 520 is located in the notch, and the fourth 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 screw rod 300 rotates forward, the fourth pin 520 is driven to rotate forward by the first transmission surface 2212 on the outer transmission sleeve 221 to make the self-locking torsion spring 500 contract, and when the screw rod 300 reverses under the action of the load, the fourth 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 screw rod 300 to reverse, the third 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.

[0078] 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 third pin and the fourth pin can be adapted accordingly, which will not be described in detail here.

[0079] In order to realize the axial limiting of the self-locking torsion spring 500, the outer transmission sleeve 221 in the embodiment further comprises a 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, i.e. the top of at least one of the transmission blocks 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 fourth pin 520 to increase the contact area of the fourth pin 520 with the transmission block 2221, thereby increasing the installation reliability of the fourth pin 520.

[0080] Further, the speed reduction assembly 200 in the embodiment also 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.

[0081] For the convenience of understanding, the working process of the electric push rod in the embodiment is described as follows:

[0082] In normal state, the torsional spring brake 700 implements circumferential braking on the brake sleeve 231, at this time, the planet carrier 213 is locked and cannot rotate, the motor 100 can drive the lead screw 300 to rotate forward to elongate the telescopic assembly 400 or rotate reversely to shorten the telescopic assembly 400 through the gear ring 214 in the planetary gear set 210, and the load can be pushed to a specified height by elongation of the telescopic assembly 400. The lead screw 300 is braked by the contact of the self-locking torsional spring 500 and the self-locking sleeve 600 to prevent the load from descending.

[0083] When it is needed to quickly release the electric push rod, the torsional spring brake 700 can be switched to the release state by operating the release device 710 to release the circumferential braking on the brake sleeve 231, at this time, the planet carrier 213 can rotate freely, and the lead screw 300 can be reversely rotated by the action of the load or pressing the lead screw 300, although the reverse rotation of the lead screw 300 drives the self-locking torsional spring 500 to expand outward and contact the self-locking sleeve 600, but the self-locking sleeve 600 and the brake sleeve 231 can also realize free rotation, so that the self-locking between the self-locking torsional spring 500 and the self-locking sleeve 600 is disabled, thereby the lead screw 300 can be reversely rotated quickly to make the telescopic assembly 400 retract quickly, and the quick release function is realized without the need of driving by the motor 100.

[0084] Finally, as Figure 5As shown, the screw rod 300 in the embodiment is in spline transmission with the inner transmission sleeve 222, the screw rod 300 is in rotational cooperation with the sun gear 211 through the bearing 310, the screw rod 300 is axially movable relative to the planetary gear set 210, the lower end of the screw rod 300 is provided with a limiting piece 320 fixed through a screw, the lower end of the screw rod 300 is provided with a 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 when being driven to retract by the motor 100, the screw rod 300 is pulled out because the inner tube 410 cannot be retracted under the driving of the nut 430, at this time, the outer spline on the screw rod 300 can be disengaged from the inner spline on the inner transmission sleeve 222, that is, the connection between the screw rod 300 and the speed reduction assembly 200 is disconnected, the screw rod 300 stops rotating, the nut 430 stops moving, and the inner tube 410 stops retracting, so that the anti-clamping effect is realized. When the screw rod 300 is pulled out, the spring 330 is compressed, so when the clamped object or human body is removed, the screw rod 300 can be pulled back because the spring 330 has restoring elastic force after being compressed, so that the outer spline on the screw rod 300 is re-engaged with the inner spline on the inner transmission sleeve 222, and the electric push rod resumes normal operation.

[0085] It can be understood that, in other embodiments of the utility model, the worm and gear has the characteristics of self-locking, and when the screw rod is reversed under the action of load, the worm and gear can be self-locked to brake the screw rod, so that the self-locking torsional spring and the transmission sleeve and other structures can be omitted, and the gear ring is directly connected with the screw rod through spline cooperation.

[0086] The above is only a specific embodiment of the utility model, but the protection scope of the utility model is not limited to this, and those skilled in the art should understand that the utility model includes but is not limited to the contents described in the drawings and the above specific embodiment. Any modification not deviating from the function and structural principle of the utility model will be included in the scope of claims.

Claims

1. An electric push rod, comprising: a motor and a speed reduction assembly; and a screw rod and a telescopic assembly, the screw rod is driven to rotate by power transmitted from the speed reduction assembly, the telescopic assembly is driven to linearly extend and retract by the screw rod; characterized in that the speed reduction assembly comprises a planetary gear set, the planetary gear set comprises a sun gear driven by the motor, a ring gear for driving the screw rod to rotate, a carrier rotatingly arranged in a first housing, and a plurality of planet gears rotatingly arranged on the carrier, the screw rod penetrates through the sun gear and is rotatable relative to the sun gear, the carrier is connected with a brake sleeve fixedly arranged in a circumferential direction of the carrier; the electric push rod further comprises a torsion spring brake, the torsion spring brake has a releasing state for releasing the circumferential brake of the brake sleeve and a locking state for circumferentially braking the brake sleeve in a normal state, when the torsion spring brake is in the locking state, the carrier is circumferentially locked, when the torsion spring brake is in the releasing state, the carrier is freely rotatable. the speed reduction assembly further comprises the first housing for accommodating the planetary gear set, the torsion spring brake comprises a brake torsion spring for tightly holding the brake sleeve in the normal state and a releasing device, the brake torsion spring comprises a first leg and a second leg fixedly arranged on the first housing, the releasing device is used for pulling the first leg to release the brake sleeve of the brake torsion spring to release the circumferential brake of the brake sleeve.

2. An electric push rod as claimed in claim 1, characterized in that the releasing device comprises a releasing plate slidingly arranged on the first housing, the releasing plate is connected with the first leg, driving the releasing plate to move to pull the first leg to rotate in a loosening direction of the brake torsion spring can release the brake sleeve of the brake torsion spring.

3. An electric push rod as claimed in claim 2, characterized in that the releasing device further comprises a releasing pull rod, the releasing plate is provided with a guide slot extending along an axial direction of the screw rod and arranged in an inclined manner, the releasing pull rod is provided with a transmission pin inserted into the guide slot and slidingly matched with the guide slot, pulling the releasing pull rod to move towards one end of the axial direction of the screw rod to drive the releasing plate to move to release the brake sleeve of the brake torsion spring.

4. An electric push rod as claimed in claim 3, characterized in that the releasing plate is provided with a connecting hole, the first leg is inserted into the connecting hole.

5. An electric push rod as claimed in claim 3, characterized in that the ring gear drives the screw rod to rotate through a transmission sleeve, a self-locking torsion spring is arranged outside the transmission sleeve, the electric push rod further comprises a self-locking sleeve arranged outside the self-locking torsion spring and fixedly arranged in a circumferential direction of the brake sleeve, when the ring gear drives the screw rod 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, when the screw rod reverses under the action of a load, the transmission sleeve drives the self-locking torsion spring to expand to contact the self-locking sleeve to brake the screw rod.

6. An electric push rod as claimed in claim 1, characterized in that the transmission sleeve comprises an outer transmission sleeve fixedly arranged in a circumferential direction of the ring gear and an inner transmission sleeve fixedly arranged in a circumferential direction of the screw rod, when the outer transmission sleeve drives the screw rod to rotate 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 for idling relative to the inner transmission sleeve and a working stroke for driving 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.

7. An electric push rod as claimed in claim 6, characterized in that ​ 8. An electric push rod as claimed in claim 7, characterized in that The outer transmission sleeve is circumferentially spaced apart from a plurality of transmission grooves, the inner transmission sleeve is provided with a transmission block inserted into the transmission groove, the transmission groove has 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 is driven by the inner transmission sleeve to rotate in a positive direction and the screw reversely rotates under the load, the transmission block abuts against the first transmission surface.

9. An electric push rod as claimed in claim 8, characterized in that The self-locking torsion spring includes a third pin and a fourth pin, the third pin is inserted into the transmission groove and located outside the gap, and the axial projection of the third pin is located in the axial projection of the gap, the fourth pin is clamped between the side of the transmission block away from the gap and the side wall of the transmission groove, when the screw rotates in a positive direction, the fourth pin is driven to rotate by the outer transmission sleeve to make the self-locking torsion spring contract, when the screw reversely rotates under the load, the fourth pin is driven to rotate by the inner transmission sleeve to make the self-locking torsion spring expand, when the outer transmission sleeve is in an idle stroke, the third pin is driven to make the self-locking torsion spring contract.

10. An electric push rod according to any one of claims 1 to 9, characterized in that The speed reduction assembly further includes a worm wheel and a worm, the worm wheel is connected with the sun gear and rotates synchronously, the worm is connected with the output shaft of the motor, when the screw reversely rotates under the load, the worm wheel and the worm are self-locked to brake the screw.

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