Linear actuator

Abstract

The invention discloses a linear actuator which comprises a motor, a tubular telescopic component and a force transmission chain. The force transmission chain is arranged to transmit power of the motor to the tubular telescopic component so as to drive the tubular telescopic component to do linear motion. The first force transmission chain comprises a planet wheel speed reducing mechanism in transmission connection with the output end of the motor, a second force transmission chain in transmission connection with the first force transmission chain, and a third force transmission chain in transmission connection with the second force transmission chain; the third force transmission chain comprises a lead screw and a transmission nut which is in threaded fit with the lead screw, and the transmission nut is connected with the tubular telescopic component; the force transmission direction of the first force transmission chain intersects with the force transmission direction of the second force transmission chain, and the force transmission direction of the second force transmission chain intersects with the force transmission direction of the third force transmission chain. The situation that the output shaft of the motor is perpendicular to the lead screw is avoided, the overall size of the linear actuator is reduced, and transportation and installation are convenient.

Description

Technical Field

[0001] The present invention relates to the field of linear actuators, and in particular to a linear actuator. Background Art

[0002] Electric-driven actuation systems are widely used in electric lifting tables, electric beds, electric sofas / chairs and other equipment. These devices rely on the output torque of the motor to achieve linear displacement or move the load in other ways. Usually, the motor cannot directly output torque to the actuator (screw nut assembly) because it cannot obtain sufficient thrust. A reduction mechanism is required to convert and transmit power between them, such as a worm gear transmission. However, the reduction ratio it provides is low in upper limit and narrow in range, resulting in a small rated load of the actuation system and limited application. CN118293189A discloses a common linear drive using a worm gear as a reduction mechanism.

[0003] There is also a prior art that uses a planetary gear reduction mechanism, as described in CN109083998A: through the transmission action of the planetary gear assembly, the rotation speed of the worm wheel can be reduced and the torque of the lead screw can be increased, so that the lead screw has a greater thrust, but the planetary gear reduction mechanism and the worm wheel are arranged in the same straight line direction, which undoubtedly increases the length of the actuator.

[0004] In the above solutions, because a worm gear transmission is used, the motor is vertically arranged relative to the lead screw. The vertically placed motor needs to occupy a larger lateral space of the linear actuator, which is not conducive to the transportation and installation of the product. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, the present invention provides a linear actuator having the advantage of small overall volume.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A linear actuator comprising:

[0008] Motor;

[0009] Tubular telescopic member;

[0010] A force transmission chain, configured to transmit power of the motor to the tubular telescopic component to drive the tubular telescopic component to perform linear motion;

[0011] The force transmission chain comprises:

[0012] A first force transmission chain includes a planetary gear reduction mechanism drivingly connected to an output end of the motor;

[0013] A second force transmission chain drivingly connected to the first force transmission chain comprises a speed transmission mechanism having gears and / or worm gears;

[0014] A third force transmission chain drivingly connected to the second force transmission chain, comprising a screw rod and a transmission nut threadedly engaged with the screw rod, wherein the transmission nut is connected to the tubular telescopic component;

[0015] The force transmission direction of the first force transmission chain intersects with the force transmission direction of the second force transmission chain, and the force transmission direction of the second force transmission chain intersects with the force transmission direction of the third force transmission chain;

[0016] A clutch is used to lock the inner gear ring of the planetary gear reduction mechanism to prevent rotation;

[0017] A release component drives the clutch to release the inner ring gear and activates the release function of the linear actuator.

[0018] By adopting the above technical solution, during normal operation, the torque generated by the motor is transmitted to the screw rod through the first force transmission chain and the second force transmission chain, wherein the first force transmission chain includes a planetary gear reduction mechanism, and the second force transmission chain is transmitted to the screw rod including a speed change transmission mechanism, so that the planetary gear reduction mechanism and the speed change transmission mechanism are used to reduce speed and increase torque multiple times, and the deceleration effect and torque increase effect are good; when released, the load drives the screw rod to rotate in the opposite direction, and is transmitted to the first force transmission chain through the second force transmission chain. This time, the release component drives the clutch to release the inner gear ring, so that the inner gear ring rotates to complete the force unloading, and the second force transmission chain plays a role of increasing speed and reducing torque, so that the load transmitted to the first force transmission chain The torque becomes smaller, thereby starting to reduce the impact force on the reduction mechanism; the output end of the motor is transmission-connected to the planetary gear reduction mechanism of the first force transmission chain, so that the axial direction of the output end of the motor is parallel to the force transmission direction of the first force transmission chain, and at the same time, the force transmission direction of the first force transmission chain intersects with the force transmission direction of the second force transmission chain, and the force transmission direction of the second force transmission chain intersects with the force transmission direction of the third force transmission chain. The force transmission direction of the first force transmission chain axially parallel to the output end of the motor and the force transmission direction of the third force transmission chain where the lead screw is located will not be perpendicular to each other, thus avoiding the situation where the output shaft of the motor and the lead screw are perpendicular to each other, reducing the overall volume of the linear actuator, and facilitating transportation and installation.

[0019] Optionally, the force transmission direction of the first force transmission chain is from the input end to the output end of the planetary gear reduction mechanism;

[0020] The force transmission direction of the second force transmission chain is from the input end to the output end of the speed change transmission mechanism;

[0021] The force transmission direction of the third force transmission chain is the displacement direction of the transmission nut on the screw rod;

[0022] The force transmission direction of the first force transmission chain and the force transmission direction of the third force transmission chain are arranged in parallel.

[0023] By adopting the above technical solution, when the force transmission direction of the first force transmission chain and the force transmission direction of the third force transmission chain are set to be parallel, compared with the previous method of setting the motor perpendicular to the lead screw, the first force transmission chain and the third force transmission chain are close to each other in a parallel posture. Generally speaking, the motor can directly output torque to the first force transmission chain, which makes the output shaft axial direction of the motor parallel to the force transmission direction of the first force transmission chain, and then makes the motor parallel to the lead screw, and the overall volume of the linear actuator is reduced, which is convenient for transportation and installation in a small space.

[0024] Optionally, the first force transmission chain and the third force transmission chain are located on the same side of the second force transmission chain.

[0025] By adopting the above technical solution, when the first force transmission chain and the third force transmission chain are located on the same side of the second force transmission chain, the overall length of the linear actuator depends on the relatively larger length of the first force transmission chain and the third force transmission chain, rather than the sum of the lengths of the first force transmission chain and the third force transmission chain, thereby greatly reducing the overall length of the linear actuator.

[0026] Optionally, the linear actuator further comprises a centrifugal brake for balancing the load torque applied to the first force transmission chain after the linear actuator releases its function.

[0027] By adopting the above technical solution, when released, the centrifugal brake balances the load torque applied to the first force transmission chain and plays a braking role, thereby reducing the reversal speed of the screw rod, thereby reducing the retraction speed of the tubular telescopic part, avoiding the impact of the tubular telescopic part due to excessive retraction speed.

[0028] Optionally, the planetary gear reduction mechanism further includes:

[0029] A sun gear drivingly connected to the output end of the motor;

[0030] a planetary gear meshed between the sun gear and the internal gear;

[0031] A retaining frame drivingly connected to the third power transmission chain, used for carrying the planetary gear;

[0032] When the inner gear ring is locked by the clutch, the power of the motor does not trigger the centrifugal brake, and is output to the third power transmission chain through the retaining frame to reduce speed and increase torque;

[0033] When the inner gear ring is released by the clutch, the load torque is output to the centrifugal brake through the inner gear ring to increase the speed and reduce the torque, and the centrifugal brake is triggered to brake by the load torque.

[0034] By adopting the above technical solution, during normal operation, the inner gear ring is locked by the clutch, and the power of the motor does not trigger the centrifugal brake, thereby avoiding affecting normal operation; when released, the inner gear ring is released, and at this time the sun gear cannot rotate due to the braking torque of the motor itself, and the load torque is transmitted to the inner gear ring through the retaining frame and the planetary gear to drive it to rotate, and the rotating inner gear ring activates the centrifugal brake, which plays a braking role.

[0035] Optionally, the centrifugal brake comprises:

[0036] A rotating component driven to rotate by the inner gear ring;

[0037] A brake housing, providing a braking friction surface;

[0038] The brake pad disposed between the rotating member and the brake housing generates centrifugal motion due to the rotational motion of the rotating member and contacts the brake friction surface.

[0039] By adopting the above technical solution, the inner gear ring drives the rotating part to rotate, and the rotating part drives the brake block to generate centrifugal motion so as to contact the brake friction surface of the brake shell to generate friction, thereby generating directional braking force to achieve the deceleration braking effect; in addition, the greater the load torque, the greater the rotation speed of the rotating part, and thus the greater the friction braking force generated, and the smaller the load torque, the smaller the rotation speed of the rotating part, and thus the smaller the friction braking force generated, so that similar release speeds can be achieved under different loads.

[0040] Optionally, the rotating component is configured as a part of the inner gear ring or is attached to the inner gear ring.

[0041] By adopting the above technical solution, when the rotating component is integrated with the inner gear ring, the number of parts is reduced, which is convenient for assembly; when the rotating component is attached to the inner gear ring, it is convenient for subsequent disassembly and replacement of the rotating component.

[0042] Optionally, one of the brake block and the rotating component is provided with a radial guide groove, and the other is provided with a radial guide block, and the radial guide block is inserted into the radial guide groove to guide the centrifugal movement of the brake block;

[0043] Alternatively, the outer peripheral surface of the rotating component has a guide groove adapted to the brake block, the brake block is embedded in the guide groove, and the brake block and the rotating component keep synchronous rotation in the circumferential direction and can move relative to each other in the radial direction;

[0044] Alternatively, one end of the brake block is pivotally connected to the rotating component, and the other end constitutes a free end capable of radially moving relative to the rotating component.

[0045] By adopting the above technical solution, the brake block will rotate together with the rotating component, and centrifugal force will be generated during the rotation. At least part of the brake block will press against the brake friction surface due to the centrifugal force to generate friction.

[0046] Optionally, the linear actuator further comprises a torsion spring brake for balancing the load torque applied to the third force transmission chain after the linear actuator activates a release function.

[0047] By adopting the above technical solution, before the load torque is transmitted to the centrifugal brake, reverse braking is first performed through the torsion spring brake, so that the load torque transmitted to the centrifugal brake will be relatively smaller, thereby reducing the wear of the centrifugal brake and increasing the service life of the centrifugal brake; in addition, the centrifugal brake and the torsion spring brake play a role in balancing the load torque together, so that the entire actuator can withstand a larger load torque, and there is no need to set the braking performance of the centrifugal brake and the torsion spring brake in a scenario where the two work separately; when one of the centrifugal brake and the torsion spring brake fails, the entire actuator still has the function of balancing the load torque.

[0048] Optionally, the torsion spring brake comprises a first torsion spring seat, a second torsion spring seat, a braking torsion spring and a friction element, wherein the first torsion spring seat is non-rotatably connected to the lead screw;

[0049] When the screw rotates in the first direction, the braking torsion spring holds the first torsion spring seat and the second torsion spring seat tightly to form a braking state, and the friction damping force provided by the friction element to the second torsion spring seat balances the load torque applied to the third force transmission chain;

[0050] When the lead screw rotates in a second direction opposite to the first direction, the brake torsion spring is forced to release the first torsion spring seat.

[0051] By adopting the above technical solution, during braking, the screw rod rotates in the opposite direction to drive the first torsion spring seat to move and rotate. During this process, the torsion force of the braking torsion spring gradually increases, thereby driving the second torsion spring seat and the friction element to rotate together, thereby generating friction to achieve braking effect.

[0052] Optionally, the clutch includes a fixed sleeve, a movable sleeve and a biasing element, the connection between the fixed sleeve and the movable sleeve allows the two to move axially relative to each other and be fixed circumferentially relative to each other, the movable sleeve engages with the inner gear ring to implement anti-rotation locking, the release component drives the movable sleeve to disengage from the inner gear ring, and the movable sleeve maintains a tendency to engage with the inner gear ring due to the biasing force of the biasing element.

[0053] By adopting the above technical solution, the inner gear ring is stopped and unlocked by engaging or disengaging the movable sleeve axially moving relative to the fixed sleeve, and the structure is simple. At the same time, the presence of the biasing element makes it difficult for the movable sleeve to disengage from the inner gear ring, thereby ensuring normal operation.

[0054] Optionally, the engagement between the movable sleeve and the inner gear ring is configured as one of a ratchet fit, a spline fit and an axial hole pin fit.

[0055] By adopting the above technical solution, one of the ratchet fit, spline fit and axial hole pin fit can limit the rotation of the movable sleeve and the inner gear ring in at least one direction, with more configurations and more flexible combinations.

[0056] Optionally, the linear actuator further comprises a housing for accommodating the first force transmission chain and the second force transmission chain, and the fixing sleeve is directly or indirectly fixed to the housing.

[0057] By adopting the above technical scheme, the first force transmission chain and the second force transmission chain are arranged in the shell, the first force transmission chain and the second force transmission chain are well protected, and the installation and support of the first force transmission chain and the second force transmission chain are convenient; the fixed sleeve is directly or indirectly fixed to the shell, and the fixing of the fixed sleeve is more convenient and stable, which is conducive to improving the accuracy of the axial movement of the movable sleeve.

[0058] Optionally, the linear actuator also includes a partition fixedly connected to the shell, the first force transmission chain is accommodated between the partition and the first side of the shell, the second force transmission chain is accommodated between the partition and the second side of the shell opposite to the first side, and the fixed sleeve is fixed to the partition.

[0059] By adopting the above technical solution, the partition is used as an intermediate support, so that the installation positions of the first force transmission chain and the second force transmission chain are more stable.

[0060] Optionally, the release component includes an operating rod and a shift rod, and the shift rod is pulled by the operating rod to produce axial translation or rotation, so as to drive the clutch to release the inner gear ring.

[0061] By adopting the above technical solution, the lever drives the clutch to move axially, which has a simple structure and is easy to operate.

[0062] Optionally, an annular stop is provided on the clutch along its circumference, and the shift rod has an arc-shaped shift block, and the shift block axially pushes against the annular stop to drive the clutch.

[0063] By adopting the above technical solution, the annular stopper cooperates with the arc-shaped shifting block of the shifting rod, which is simple to process and convenient to connect.

[0064] Optionally, the release component includes at least two groups of operating rods and shifting rods distributed along the circumference of the clutch, and all the operating rods are connected by connecting rods so as to be pulled synchronously.

[0065] By adopting the above technical solution, all operating rods and levers distributed along the circumference of the clutch can be moved synchronously through the connecting rod, which is easy to operate. In addition, the cooperation between multiple levers and the clutch makes the relative position between the two more stable, thereby making the movement direction of the driven clutch more accurate.

[0066] Optionally, the speed change transmission mechanism includes:

[0067] An input component configured as one of a gear, a worm wheel, and a worm, and configured to be drivingly connected to a planetary gear holder in the planetary gear reduction mechanism;

[0068] An output component configured as one of a gear, a worm wheel, and a worm, and used for fixed connection with the lead screw;

[0069] The speed change unit engages the input member and the output member to form at least two speed change stages.

[0070] By adopting the above technical solution, the speed change unit with at least two speed change stages can achieve a better deceleration effect, thereby further increasing the torque of the screw rod and making the screw rod have a greater thrust. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 It is a structural schematic diagram of the present invention.

[0072] Figure 2 It is a schematic structural diagram of the cross section of the present invention.

[0073] Figure 3 It is a schematic diagram of the structure of the present invention with the external shell omitted.

[0074] Figure 4 It is a schematic structural diagram of the cross section of the motor side of the present invention.

[0075] Figure 5 It is a schematic structural diagram of the cross section of the planetary gear set of the present invention.

[0076] Figure 6 It is an exploded schematic diagram of the present invention.

[0077] Figure 7 It is an exploded schematic diagram of the planetary gear set of the present invention.

[0078] Figure 8 It is a schematic structural diagram of the clutch and the inner gear ring of the present invention.

[0079] Fig. 9It is a structural schematic diagram of the torsion spring brake of the present invention.

[0080] Fig.10 It is a schematic diagram of the force transmission chain direction of other embodiments of the present invention.

[0081] Fig.11 It is a schematic structural diagram of a cross section of other embodiments of the present invention.

[0082] Description of reference numerals:

[0083] 10. Outer tube; 11. Upper shell; 12. Lower shell; 13. Shell; 14. Motor cover; 15. Partition plate; 16. Top bearing;

[0084] 20. Tubular telescopic components;

[0085] 30. telescopic driving mechanism; 31. screw rod; 32. transmission nut;

[0086] 40. Speed-changing transmission mechanism; 41. Level 3 spur teeth; 42. Central transmission shaft; 43. Level 2 second spur teeth; 44. Level 2 first spur teeth; 45. Level 1 spur teeth;

[0087] 50. Motor;

[0088] 60. planetary gear reduction mechanism; 61. cage; 611. retaining frame; 612. planetary gear shaft; 613. bottom plate; 614. snap ring; 62. planetary gear; 63. sun gear; 64. inner gear ring; 640. locking spline groove; 641. radial guide block; 65. brake block; 650. radial guide groove; 66. brake housing; 661. mounting strip;

[0089] 70, clutch; 71, movable sleeve; 711, sliding spline; 712, annular stopper; 713, locking spline; 72, fixed sleeve; 73, compression spring;

[0090] 80. Torsion spring brake; 81. First torsion spring seat; 82. Braking torsion spring; 83. Second torsion spring seat; 84. Friction element;

[0091] 90, release component; 91, connecting rod; 911, external screw; 92, operating rod; 93, lever;

[0092] 100. First force transmission chain;

[0093] 200, second force transmission chain;

[0094] 300, third force transmission chain;

[0095] a, first force transmission direction; b, second force transmission direction; c, third force transmission direction. DETAILED DESCRIPTION

[0096] The following is combined with Figure 1-11 The present invention is described in further detail.

[0097] Embodiment 1: A linear actuator is disclosed, referring to Figure 1-Figure 3 , including an outer tube 10, a shell 13, a motor 50, a tubular telescopic component 20 and a force transmission chain; the force transmission chain includes a first force transmission chain 100, a second force transmission chain 200 and a third force transmission chain 300; the motor 50 is fixed to the shell 13 by bolts; the first force transmission chain 100 and the second force transmission chain 200 are arranged in the shell 13; the third force transmission chain 300 is arranged on the shell 13; the outer tube 10 is fixed to the shell 13; the tubular telescopic component 20 is telescopically arranged in the outer tube 10; the power of the motor 50 sequentially passes through the first force transmission chain 100, the second force transmission chain 200 and the third force transmission chain 300 to drive the tubular telescopic component 20 to perform linear motion. When the tubular telescopic component 20 extends and moves, the force transmission direction of the first force transmission chain 100 is the first force transmission direction a, the force transmission direction of the second force transmission chain 200 is the second force transmission direction b, and the force transmission direction of the third force transmission chain 300 is the third force transmission direction c.

[0098] refer to Figure 1-Figure 4 The housing 13 includes an upper shell 11, a lower shell 12 and a partition 15; the upper shell 11 and the lower shell 12 are screwed together to form a transmission box with a hollow interior; the outer tube 10 is fixed to the end surface of the upper shell 11 away from the lower shell 12 by screws; the partition 15 is fixed in the upper shell 11 by screws; the first force transmission chain 100 is located between the side of the partition 15 close to the motor 50 and the upper shell 11; the second force transmission chain 200 is located between the side of the partition 15 away from the motor 50 and the lower shell 12; the first force transmission chain 100 and the third force transmission chain 300 are located on the same side of the partition 15 and the force transmission directions of the two are arranged in parallel. The overall length of the linear actuator depends on The relatively large length of the first force transmission chain 100 and the third force transmission chain 300 is not the sum of the lengths of the first force transmission chain 100 and the third force transmission chain 300, so the overall length of the linear actuator is greatly reduced; in addition, compared with the previous method of setting the motor perpendicular to the lead screw, the first force transmission chain 100 and the third force transmission chain 300 are close to each other in a parallel posture. Generally speaking, the motor can directly output torque to the first force transmission chain 100, which makes the output shaft axial direction of the motor parallel to the first force transmission direction a, and then makes the motor parallel to the lead screw, and the overall volume of the linear actuator is reduced, which is convenient for transportation and installation in a small space.

[0099] refer to Figure 1 and Figure 3 , in order to protect the motor 50, refer to Figure 1 and Figure 2 The motor 50 is provided with a motor cover 14; the motor cover 14 is fixed to the upper shell 11 by screws.

[0100] refer to Figure 2-Figure 7 The first force transmission chain 100 includes a planetary gear reduction mechanism 60; the planetary gear reduction mechanism 60 includes a sun gear 63, a retainer 61, four planetary gears 62 rotatably connected to the retainer 61, and an inner gear ring 64; the sun gear 63 is coaxially arranged in the inner gear ring 64; the four planetary gears 62 are located between the sun gear 63 and the inner gear ring 64; the planetary gears 62 are meshed with the sun gear 63 and the inner gear ring 64 respectively; the end of the output shaft of the motor 50 is double flat; the end surface of the rotating shaft of the sun gear 63 close to the motor 50 is formed with a slot that matches the output shaft of the motor 50. The input end of the first force transmission direction a is the sun gear 63, and the output end is the retainer 61.

[0101] refer to Figure 2-Figure 7 The retaining frame 61 includes a retaining main frame 611 and a cross-shaped bottom plate 613; the retaining main frame 611 and the cross-shaped bottom plate 613 are formed with four connecting through holes; the planetary gear 62 is integrally formed with a planetary gear shaft 612; the two ends of the planetary gear shaft 612 pass through the connecting through holes on the corresponding sides; the two ends of the planetary gear shaft 612 are respectively formed with annular groove-shaped clamping grooves; a clamping ring 614 is clamped in the clamping groove; the center of the bottom plate 613 is formed with a vertically penetrating central through hole; the sun gear 63 passes through the central through hole During installation, the four planetary gear shafts 612 pass through the four central through holes of the retaining main frame 611, and then the base plate 613 is sleeved on the other ends of the four planetary gear shafts 612, and finally the retaining rings 614 are clamped in the clamping grooves of the four planetary gear shafts 612; both ends of the planetary gear 62 are respectively formed with coaxially arranged annular contact rings, and the contact rings are connected to the base plate 613 or the retaining main frame 611. Since the area of ​​the contact rings is smaller than the end area of ​​the planetary gear 62, such a design can reduce friction.

[0102] refer to Figure 2 , Figure 3 and Figure 5 The third force transmission chain 300 includes a telescopic drive mechanism 30, which includes a screw rod 31 and a transmission nut 32 threadedly engaged with the screw rod; the screw rod 31 is connected to the partition 15 through a bearing; the axial direction of the screw rod 31 is parallel to the axial direction of the retaining frame 61. The tubular telescopic component 20 is fixed to the transmission nut 32 by screws. When the tubular telescopic component 20 is extended, the third force transmission direction c is the displacement direction of the transmission nut 32 on the screw rod 31, so that the third force transmission direction c is parallel to the first force transmission direction a.

[0103] refer to Figure 2 , Figure 3 and Figure 5The second force transmission chain 200 includes a speed transmission mechanism 40; the speed transmission mechanism 40 includes a primary spur gear 45, a secondary spur gear and a tertiary spur gear 41; the tertiary spur gear 41 is coaxially connected to the screw rod 31 and the connection method between the two can refer to the connection method between the rotating shaft of the sun gear 63 and the output shaft of the motor 50, that is, the connection method through a non-circular hole and a non-cylindrical shaft; the partition 15 is rotatably connected to a central transmission shaft 42 through a bearing; the secondary spur gear is coaxially fixed on the central transmission shaft 42; the secondary spur gear includes a secondary second spur gear 43 and a secondary first spur gear 44 connected as one body; the primary spur gear 45 is integrally formed The type has a primary spur gear shaft; the primary spur gear 45 meshes with the secondary first spur gear 44; the secondary second spur gear 43 meshes with the tertiary spur gear 41; the diameter of the primary spur gear 45 is smaller than the diameter of the secondary first spur gear 44; the diameter of the secondary second spur gear 43 is smaller than the diameter of the tertiary spur gear 41; the end of the screw rod 31 away from the outer tube 10 is double flat, and the center of the tertiary spur gear 41 is formed with a hole that matches one end of the double flat of the screw rod 31; the end of the rotating shaft of the retaining frame 61 holding the main frame 611 is double flat; the end face of the primary spur gear shaft of the primary spur gear 45 is formed with a slot that matches the rotating shaft of the star main frame 611. The input end of the second force transmission direction b is the primary spur gear 45, and the output end is the tertiary spur gear 41.

[0104] The above-mentioned speed change transmission mechanism 40 is a two-stage speed change. Of course, according to actual needs, the speed change transmission mechanism 40 can also be provided with a multi-stage speed change such as a three-stage speed change.

[0105] In addition, the second force transmission chain 200 may also change speed through a worm gear instead of a gear meshing speed change. Of course, the gear and the worm gear may be combined to achieve the speed change purpose. At the same time, other common speed change structures may also be used.

[0106] To sum up, during normal operation, the speed transmission mechanism 40 can select one of the gear, worm wheel and worm as the input component, which is connected to the retaining frame 61; and can select one of the gear, worm wheel and worm as the output component, which is connected to the screw 31.

[0107] In order to improve the installation stability of the planetary gear reduction mechanism 60 and the speed change transmission mechanism 40, refer to Figure 3 An inner abutment column 141 is formed on the inner side wall of the lower shell 14; a top bearing 16 is installed on the inner abutment column 141; and a coaxially arranged mounting groove that cooperates with the top bearing 16 is formed at the center of the end of the first-stage spur gear 45.

[0108] In order to realize the release function, that is, the load drives the tubular telescopic part 20 to contract, a clutch 70 and a release part 90 are also arranged between the upper shell 11 and the partition 15; the clutch 70 is used to implement anti-rotation locking of the inner ring gear 64; the release part 90 is used to drive the clutch 70 to release the inner ring gear 64 and activate the release function of the linear actuator.

[0109] refer to Figure 4-Figure 6 and Figure 8 The clutch 70 includes a fixed sleeve 72, a movable sleeve 71 and a compression spring 73; the movable sleeve 71 includes a circular center clutch ring; one end of the central clutch ring is formed with a coaxial circular ring-shaped sliding ring; five sliding splines 711 evenly distributed on the outer cylindrical surface of the sliding ring are formed; the fixed sleeve 72 is connected to the partition 15 by screws; the bottom of the sliding cavity of the fixed sleeve 72 is formed with a clutch through hole for the primary spur gear shaft of the primary spur gear 45 to pass through; one end of the fixed sleeve 72 is formed with a sliding cavity for the axial sliding of the sliding ring; one end of the compression spring 73 is pressed against the The sliding cavity is against the bottom of the sliding cavity, and the other end is against the movable sleeve 71; five sliding spline grooves are formed on the inner cylindrical surface of the sliding cavity for the sliding spline 711 to move axially; the inner diameter of the inner gear ring 64 is larger than the center clutch ring; four locking splines 713 are formed on the outer cylindrical surface of the center clutch ring and are evenly distributed around the circumference; the inner gear ring 64 is formed with four locking spline grooves 640 for the locking spline 713 to be axially inserted at one end thereof close to the movable sleeve 71; the function of the compression spring 73 is to bias the movable sleeve 71 toward the inner gear ring 64 so that the locking spline 713 is inserted into the locking spline groove 640. In addition, the outer diameter of the center clutch ring is larger than the inner diameter of the sliding cavity, so that the moving direction of the movable sleeve 71 away from the inner gear ring 64 is limited by the spacing, and when the movable sleeve 71 reaches the limit position of the moving side away from the inner gear ring 64, the locking spline 713 is disengaged from the locking spline groove 640.

[0110] The above is to achieve the stopping of the inner gear ring 64 by spline matching, that is, in normal operation, the inner gear ring 64 cannot rotate, so that the power of the motor 50 can be transmitted to the primary spur 45 through the sun gear 63, the planetary gear 62, and the retainer 61 in sequence. Therefore, the engagement method of the inner gear ring 64 and the movable sleeve 71 can also be one of the ratchet matching and the axial hole pin matching. When the ratchet is matched, one of the inner gear ring 64 and the movable sleeve 71 is fixed with a ratchet, and the other is connected with a ratchet in rotation. In normal operation, the ratchet and the ratchet match so that the inner gear ring 64 cannot rotate forward. When released, the inner gear ring 64 can rotate in the opposite direction; when the axial hole pin is matched, one of the inner gear ring 64 and the movable sleeve 71 is formed with a hole that is not coaxial with the other but parallel to the axial direction, and the other is formed with a pin that matches it.

[0111] refer to Figure 6 and Figure 8The release component 90 includes a pair of levers 93, a pair of operating rods 92 and a connecting rod 91; the operating rods 92 correspond to the levers 93 one by one; the levers 93 include an arc-shaped shifting block and a vertical plate formed on the outer cylindrical surface of the shifting block; screws are formed at both ends of the operating rod 92; one screw of the operating rod 92 is screwed to the vertical plate of the lever 93, and the other screw vertically passes through the end of the connecting rod 91 and is screwed with a nut; a pair of annular stops 712 are formed in the middle of the movable sleeve 71; the shifting blocks of the pair of levers 93 are radially inserted between the pair of annular stops 712; the pair of operating rods 92 pass through the lower shell 12 and the connecting rod 91 is located outside the transmission box. In order to reduce friction, the movable sleeve 71 is made of self-lubricating plastic material, which ultimately reduces noise.

[0112] In order to facilitate pulling the release component 90, an outer screw 911 is vertically fixed to the middle of the end surface of the connecting rod 91 away from the transmission box; the outer screw 911 can be used to connect an external handle or a pedal to facilitate driving the release operating member; preferably, the outer screw 911 is located in the middle of a pair of operating rods 92.

[0113] Of course, the lever 93 may not be translated. The center of the vertical plate portion of the lever 93 is rotatably connected to the transmission box, and then the end of the vertical plate portion of the lever 93 away from the shift block extends out of the transmission box and the operating rod 92 is connected to it. In this way, the lever 93 is driven to rotate by the operating rod 92, and the shift block of the lever 93 abuts against and pushes the annular stopper 712 on the corresponding side, thereby driving the movable sleeve 71 to move axially along the fixed sleeve 72; due to the presence of the compression spring 73, there can be only one annular stopper 712 and it is located on the side of the shift block of the lever 93 away from the inner gear ring 64.

[0114] In addition to the above-mentioned case where the release component 90 includes a pair of levers 93 and a pair of operating rods 92, in other embodiments, the release component 90 may include more than two levers 93 and operating rods 92, so that the movable sleeve 71 will not move in a biased direction due to the eccentric force of the movable sleeve 71 during movement as when a single fork is driven. In this way, the movable sleeve 71 and the fixed sleeve 72 do not need high matching accuracy to achieve precise guiding, thereby reducing processing costs.

[0115] Working principle of embodiment 1: During normal operation, one end of the central clutch ring of the movable sleeve 71 is inserted into one end of the inner gear ring 64. At this time, the locking spline 713 is located in the locking spline groove 640 of the inner gear ring 64. Since the movable sleeve 71 is axially slidingly arranged in the fixed sleeve 72 and the fixed sleeve 72 is fixedly connected to the partition 15, the inner gear ring 64 is locked and cannot rotate; the motor 50 drives the sun gear 63 to rotate, and the sun gear 63 drives the four planetary gears 62 to rotate. Due to the action of the inner gear ring 64 in a fixed state, the four planetary gears 62 drive the retaining frame 61 to rotate, thereby driving the primary spur gear 45 to rotate, and then through the secondary first spur gear 44, the secondary second spur gear 43 and the tertiary spur gear 41, the screw rod 31 of the third force transmission chain 300 is driven to rotate, and the transmission nut 32 of the third force transmission chain 300 moves axially along the outer tube 11, thereby driving the tubular telescopic component 20 to extend.

[0116] When the motor 50 loses power, the motor 50 itself has a braking torque, so the sun gear 63 cannot rotate. In this way, the fixed sun gear 63 and the inner ring gear 64 restrict the rotation of the planetary gear 62, so that the retaining frame 61 cannot rotate, and the electric lifting linear actuator cannot retract. At this time, the connecting rod 91 is pulled, and the movable sleeve 71 is moved axially through a pair of operating rods 92 and the movable sleeve 71, so that the movable sleeve 71 is away from the inner ring gear 64, so that the locking spline 713 is disengaged from the locking spline groove 640, so that the inner ring gear 64 is unlocked and can rotate freely. Due to the weight of the load itself, the tubular telescopic component 20 is driven to retract, that is, the transmission nut 32 returns to its position, thereby driving the screw rod 31 to rotate in the opposite direction, and then the retaining frame 61 is driven to rotate through the third-stage spur teeth 41, the second-stage second spur teeth 43, the second-stage first spur teeth 44 and the first-stage spur teeth 45 in sequence, thereby achieving release, and at the same time, the inner ring gear 64 is driven to rotate by the planetary gear 62.

[0117] Embodiment 2: The difference between Embodiment 2 and Embodiment 1 is: Figure 5 and Figure 6, also includes a centrifugal brake; the centrifugal brake is connected to the inner ring gear 64 and only when the inner ring gear 64 rotates, the centrifugal brake will generate a braking force to balance the load torque applied to the first power transmission chain 100; combined with the first embodiment, it can be seen that when the tubular telescopic component 20 is extended, the inner ring gear 64 is restricted, and the inner ring gear 64 cannot rotate at this time, so the centrifugal brake will not be triggered, and the power of the motor 50 passes through the sun gear 63, the four planetary gears 62, the retainer 61, the second power transmission chain 200 and the third power transmission chain 300 in sequence, and the third power transmission chain 300 is used for deceleration and torque increase output. During this process, the centrifugal brake does not work; when the motor 50 loses power and the inner ring gear 64 is released, the load torque passes through the third power transmission chain 300, the second power transmission chain 200, the retainer 61, the planetary gear 62 and the four planetary gears 62 in sequence to drive the inner ring gear 64 to rotate, and the rotating inner ring gear 64 triggers the centrifugal brake, and the centrifugal brake generates a centrifugal braking force to balance the load torque.

[0118] refer to Figure 5 The centrifugal brake includes a rotating component and a brake housing 66; the rotating component is integrally formed on the outer circumferential surface of the inner gear ring 64 and the two are coaxially arranged; the inner gear ring 64 is located in the brake housing 66 and the two are coaxially arranged; a gap is set between the rotating component and the brake housing 66 and six fan-shaped brake blocks 65 are set in the gap.

[0119] refer to Figure 5 , wherein six radial guide blocks 641 evenly distributed on the outer circumference of the rotating component are formed; the radial guide blocks 641 correspond to the brake blocks 65 one by one; the brake blocks 65 are formed with radial guide grooves 650 cooperating with the radial guide blocks 641 in the middle of the inner surface near the inner gear ring 64; the radial guide grooves 650 are radially sleeved on the corresponding radial guide blocks 641; the brake blocks 65 can move radially in the gap between the rotating component and the brake shell 66. Of course, the radial guide blocks 641 can also be set on the inner side of the brake blocks 65, and the radial guide grooves 650 can be set on the outer circumference of the rotating component; in other embodiments, six guide grooves can also be formed on the outer cylindrical surface of the rotating component, and the brake blocks 65 move radially in the guide grooves. The above structures are all driven by the rotating inner gear ring 64 to rotate together, so that the brake blocks 65 generate centrifugal force to move radially outward, thereby generating braking force by friction with the brake shell 66.

[0120] In addition, the brake block 65 may also not use the above-mentioned radial guiding method. One end of the brake block 65 can be hinged to the outer circumference of the rotating component, while the other end is in a free state. When the brake block 65 is subjected to centrifugal force, the free end of the brake block 65 can abut against the inner circumference of the brake housing 66 to generate a reverse braking force.

[0121] In order to facilitate the connection between the brake shell 66 and the upper shell 11, a pair of mounting strips 661 evenly distributed around the circumference are formed on the outer cylindrical surface of the brake shell 66; a pair of mounting slots matching the mounting strips 661 are formed on the inner surface of the upper shell 11; the mounting slots are set to open at one end toward the lower shell 12.

[0122] In addition, in order to facilitate the subsequent maintenance of the rotating component, the rotating component can also be an independent part, which is connected to the inner gear ring 64 in a detachable manner such as screws.

[0123] Working principle of the second embodiment: when releasing, the rotating inner gear ring 64 drives the rotating parts and the brake block 65 to rotate. Since the brake block 65 is arranged to move radially, the brake block 65 moves outward due to the centrifugal force, and generates friction with the brake shell 66, thereby playing a role of reverse braking, so that the contraction speed will not be too fast and will not form an impact. In addition, the load is different, the moving speed of the transmission nut 32 is different, and the rotation speed of the screw rod 31 is also different, so the rotation speed of the inner gear ring 64 after transmission is also different, that is, the rotation of the brake block 65 is also different, and finally different friction forces are generated; the greater the load, the greater the friction force, and the greater the reverse braking force; the smaller the load, the smaller the friction force, and the smaller the reverse braking force; so it is possible to achieve a release speed close to that under different loads.

[0124] Embodiment 3: The difference between Embodiment 3 and Embodiment 1 is: Fig. 9 The linear actuator also includes a torsion spring brake 80, which includes a first torsion spring seat 81, a second torsion spring seat 83, a braking torsion spring 82 and a friction element 84; the first torsion spring seat 81 is connected to the end of the screw rod 31 away from the transmission nut 32, and the screw rod 31 and the first torsion spring seat 81 rotate synchronously at the same speed. The connection method between the two can refer to the connection method between the rotating shaft of the sun gear 63 and the output shaft of the motor 50, that is, the connection method through a non-circular hole and a non-cylindrical shaft, so that the first torsion spring seat 81 is non-rotatably connected to the screw rod 31, and a nut is screwed on the end of the screw rod 31 to separate the first torsion spring seat 81 from the screw rod 31; the two ends of the braking torsion spring 82 are respectively clamped with the first torsion spring seat 81 and the second torsion spring seat 83; when the first torsion spring seat 81 and the second torsion spring seat 83 rotate relative to each other, the braking torsion spring 82 can be released or tightened; the friction element 84 is fixed to the end of the second torsion spring seat 83 away from the braking torsion spring 82 and abuts against the inner surface of the lower shell 12. During operation, the first torsion spring seat rotates with the screw rod 31 to release the brake torsion spring; when released, the first torsion spring seat rotates with the screw rod 31 to tighten the brake torsion spring, and finally drives the second torsion spring seat and the friction element to rotate together, and the friction element and the inner surface of the lower shell 12 generate friction braking force.

[0125] In this way, when released, before the load torque is transmitted to the centrifugal brake, reverse braking is first performed through the torsion spring brake, so that the load torque transmitted to the centrifugal brake will be relatively smaller, thereby reducing the wear of the centrifugal brake and increasing the service life of the centrifugal brake; in addition, the centrifugal brake and the torsion spring brake play a role in balancing the load torque together, so that the entire actuator can withstand a larger load torque, and there is no need to set the braking performance of the centrifugal brake and the torsion spring brake in a scenario where the two work separately; when one of the centrifugal brake and the torsion spring brake fails, the entire actuator still has the function of balancing the load torque.

[0126] Example 3: Reference Figure 2 , the first force transmission direction a, the second force transmission direction b and the third force transmission direction c of the first embodiment are all on the XY plane, the first force transmission direction a intersects with the second force transmission direction b, and the second force transmission direction b intersects with the third force transmission direction c; reference Fig.10 In embodiment three, the second force transmission direction b and the third force transmission direction c can be set on the XY plane, and the first force transmission direction a can be set on the XZ plane. In this way, the first force transmission direction a and the installation direction of the motor connected to the first force transmission chain 100 can be changed to adapt to different usage spaces, which is more adaptable.

[0127] Embodiment 4: The difference between Embodiment 4 and Embodiment 2 is: Fig.11 The fixed sleeve 72 is fixed in the upper shell 11 , the planetary gear reduction mechanism 60 and the clutch 70 are located in the fixed sleeve 72 ; the clutch 70 is located between the planetary gear reduction mechanism 60 and the motor 50 ; the output shaft of the motor 50 coaxially passes through the movable sleeve 71 .

[0128] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A linear actuator, comprising: Motor; Tubular telescopic member; A force transmission chain, configured to transmit power of the motor to the tubular telescopic component to drive the tubular telescopic component to perform linear motion; It is characterized in that: the force transmission chain comprises: A first force transmission chain includes a planetary gear reduction mechanism drivingly connected to an output end of the motor; A second force transmission chain drivingly connected to the first force transmission chain comprises a speed transmission mechanism having gears and / or worm gears; A third force transmission chain drivingly connected to the second force transmission chain, comprising a screw rod and a transmission nut threadedly engaged with the screw rod, wherein the transmission nut is connected to the tubular telescopic component; The force transmission direction of the first force transmission chain intersects with the force transmission direction of the second force transmission chain, and the force transmission direction of the second force transmission chain intersects with the force transmission direction of the third force transmission chain; A clutch is used to lock the inner gear ring of the planetary gear reduction mechanism to prevent rotation; A release component drives the clutch to release the inner ring gear and activates the release function of the linear actuator.

2. A linear actuator according to claim 1, characterized in that: The force transmission direction of the first force transmission chain is from the input end to the output end of the planetary gear reduction mechanism; The force transmission direction of the second force transmission chain is from the input end to the output end of the speed change transmission mechanism; The force transmission direction of the third force transmission chain is the displacement direction of the transmission nut on the screw rod; The force transmission direction of the first force transmission chain and the force transmission direction of the third force transmission chain are arranged in parallel.

3. A linear actuator according to claim 2, characterized in that: The first force transmission chain and the third force transmission chain are located on the same side of the second force transmission chain.

4. A linear actuator according to claim 1, characterized in that: The linear actuator further comprises a centrifugal brake for balancing a load torque applied to the first force transmission chain after the linear actuator is released from function.

5. A linear actuator according to claim 4, characterized in that: The planetary gear reduction mechanism also includes: A sun gear drivingly connected to the output end of the motor; a planetary gear meshed between the sun gear and the internal gear; A retaining frame drivingly connected to the third power transmission chain, used for carrying the planetary gear; When the inner gear ring is locked by the clutch, the power of the motor does not trigger the centrifugal brake, and is output to the third power transmission chain through the retaining frame to reduce speed and increase torque; When the inner gear ring is released by the clutch, the load torque is output to the centrifugal brake through the inner gear ring to increase the speed and reduce the torque, and the centrifugal brake is triggered to brake by the load torque.

6. A linear actuator according to claim 4, characterized in that: The centrifugal brake comprises: A rotating component driven to rotate by the inner gear ring; A brake housing, providing a braking friction surface; The brake pad disposed between the rotating member and the brake housing generates centrifugal motion due to the rotational motion of the rotating member and contacts the brake friction surface.

7. A linear actuator according to claim 6, characterized in that: The rotating component is configured as a part of the inner ring gear or is attached to the inner ring gear.

8. A linear actuator according to claim 6, characterized in that: One of the brake block and the rotating component is provided with a radial guide groove, and the other is provided with a radial guide block, wherein the radial guide block is inserted into the radial guide groove to guide the centrifugal movement of the brake block; Alternatively, the outer peripheral surface of the rotating component has a guide groove adapted to the brake block, the brake block is embedded in the guide groove, and the brake block and the rotating component keep synchronous rotation in the circumferential direction and can move relative to each other in the radial direction; Alternatively, one end of the brake block is pivotally connected to the rotating component, and the other end constitutes a free end capable of radially moving relative to the rotating component.

9. A linear actuator according to claim 4, characterized in that: The linear actuator further comprises a torsion spring brake for balancing the load torque applied to the third force transmission chain after the linear actuator activates a release function.

10. A linear actuator according to claim 9, characterized in that: The torsion spring brake comprises a first torsion spring seat, a second torsion spring seat, a braking torsion spring and a friction element, wherein the first torsion spring seat is non-rotatably connected to the lead screw; When the screw rotates in the first direction, the braking torsion spring holds the first torsion spring seat and the second torsion spring seat tightly to form a braking state, and the friction damping force provided by the friction element to the second torsion spring seat balances the load torque applied to the third force transmission chain; When the lead screw rotates in a second direction opposite to the first direction, the brake torsion spring is forced to release the first torsion spring seat.

11. A linear actuator according to claim 1, characterized in that: The clutch includes a fixed sleeve, a movable sleeve and a biasing element. The connection between the fixed sleeve and the movable sleeve allows the two to move axially relative to each other and to be fixed circumferentially relative to each other. The movable sleeve is engaged with the inner gear ring to implement anti-rotation locking. The release component drives the movable sleeve to disengage from the inner gear ring. The movable sleeve is biased by the biasing force of the biasing element and maintains a tendency to engage with the inner gear ring.

12. A linear actuator according to claim 11, characterized in that: The engagement between the movable sleeve and the inner gear ring is configured as one of a ratchet fit, a spline fit and an axial hole pin fit.

13. A linear actuator according to claim 11, characterized in that: The linear actuator further comprises a housing for accommodating the first force transmission chain and the second force transmission chain, and the fixing sleeve is directly or indirectly fixed to the housing.

14. A linear actuator according to claim 13, characterized in that: The linear actuator also includes a partition fixedly connected to the shell, the first force transmission chain is accommodated between the partition and the first side of the shell, the second force transmission chain is accommodated between the partition and the second side of the shell opposite to the first side, and the fixed sleeve is fixed to the partition.

15. A linear actuator according to claim 1, characterized in that: The release component includes an operating rod and a shifting rod. The shifting rod is pulled by the operating rod to generate axial translation or rotation, so as to drive the clutch to release the inner gear ring.

16. A linear actuator according to claim 15, characterized in that: An annular stop is arranged on the clutch along its circumference, and the shifting rod has an arc-shaped shifting block, and the shifting block axially pushes against the annular stop to drive the clutch.

17. A linear actuator according to claim 16, characterized in that: The release component comprises at least two groups of operating rods and shifting rods distributed along the circumference of the clutch, and all the operating rods are connected by connecting rods so as to be pulled synchronously.

18. A linear actuator according to claim 1, characterized in that: The speed change transmission mechanism comprises: An input component configured as one of a gear, a worm wheel, and a worm, and configured to be drivingly connected to a planetary gear holder in the planetary gear reduction mechanism; An output component configured as one of a gear, a worm wheel, and a worm, and used for fixed connection with the lead screw; The speed change unit engages the input member and the output member to form at least two speed change stages.

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