Linear actuator

Abstract

The utility model discloses a linear actuator. The linear actuator comprises a motor; and a tubular telescopic member; the force transmission chain is arranged to transmit the power of the motor to the tubular telescopic component so as to drive the tubular telescopic component to do linear motion; the force transmission chain comprises a planet wheel speed reducing mechanism which is in transmission connection with the output end of the motor; the clutch is used for implementing rotation stopping locking on an inner gear ring of the planet wheel speed reducing mechanism; the release component comprises at least two groups of operating rods and shifting forks which are distributed along the circumferential direction of the clutch; the shifting fork is dragged by the operating rod to generate axial translation or rotation and is used for driving the clutch to release the inner gear ring so as to activate the release function of the linear actuator; all the operating rods are connected through a connecting rod and can be pulled synchronously. According to the clutch, the movement accuracy of the clutch can be achieved without achieving accurate guiding through high matching accuracy of parts of the clutch.

Description

Technical Field

[0001] The utility model relates to the field of linear actuators, in particular to a linear actuator. Background Art

[0002] A linear actuator, also known as an electric push rod, is widely used in fields such as furniture, medical equipment, solar power generation, etc. Its main structure includes a driving motor, an intermediate transmission mechanism, a lead screw, and a transmission nut. The working principle is that the driving motor starts to drive the lead screw to rotate through the intermediate transmission mechanism, and the rotation of the lead screw drives the transmission nut to move axially. Generally, an inner tube is connected to the transmission nut, so as to realize the telescopic movement of the inner tube.

[0003] Some existing linear actuators on the market have a release function, which is realized through a clutch or the like. However, a part of the existing clutches is realized by the rotation of a screw rod. Such a method has a troublesome overall layout and is inconvenient for synchronous operation. In addition, there is also a method realized by a single fork. This overcomes the above-mentioned defects, but in the method of driving the clutch by a single fork, the movement accuracy of the clutch is affected. Therefore, the processing of parts requires a very high production accuracy to ensure, but it has a certain processing difficulty, which will greatly increase the processing cost. Summary of the Utility Model

[0004] In order to overcome the deficiencies in the prior art, the utility model provides a linear actuator, which has the advantages of not requiring high-precision manufacturing of parts to reduce the processing cost.

[0005] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0006] A linear actuator, comprising:

[0007] A motor;

[0008] A tubular telescopic member;

[0009] A force transmission chain, which is arranged to transmit the power of the motor to the tubular telescopic member to drive the tubular telescopic member to perform linear motion;

[0010] The force transmission chain includes a planetary gear reduction mechanism that is in transmission connection with the output end of the motor;

[0011] A clutch that implements anti-rotation locking on the internal gear ring of the planetary gear reduction mechanism;

[0012] A release member, including at least two groups of operating rods and forks distributed circumferentially along the clutch; the fork is axially translated or rotated under the traction of the operating rod, and is used to drive the clutch to release the internal gear ring to activate the release function of the linear actuator; all the operating rods are connected by a connecting rod and can be synchronously tractioned.

[0013] By adopting the above technical solution, since the release component includes at least two groups of operating rods and shift forks distributed along the circumference of the clutch, and all the operating rods are connected by connecting rods and can be pulled synchronously, the operation is convenient. At the same time, the clutch will not move in a biased direction due to eccentric force during the operation process unlike when a single shift fork is driven. In this way, the clutch parts do not need high matching accuracy to achieve precise guidance to achieve clutch movement accuracy.

[0014] Optionally, an annular stop is provided on the clutch along its circumference, and the shift fork has an arc-shaped shift block, and the shift block axially pushes against the annular stop to drive the clutch.

[0015] By adopting the above technical solution, the annular stopper cooperates with the arc-shaped shifting block of the shift fork, which is simple to process and convenient to connect.

[0016] Optionally, the force transmission chain includes:

[0017] A first force transmission chain, comprising the planetary gear reduction mechanism;

[0018] A second force transmission chain drivingly connected to the first force transmission chain comprises a speed transmission mechanism having gears and / or worm gears;

[0019] 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;

[0020] 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;

[0021] 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;

[0022] The force transmission direction of the third force transmission chain is the displacement direction of the transmission nut on the screw rod;

[0023] 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.

[0024] 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.

[0025] Optionally, the first force transmission chain and the third force transmission chain are located on the same side of the second force transmission chain.

[0026] 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 among 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. Therefore, the overall length of the linear actuator is greatly reduced.

[0027] Optionally, the speed change transmission mechanism includes:

[0028] An input component configured as one of a gear, a worm wheel, and a worm, for drivingly connecting with the planet carrier in the planetary gear reduction mechanism;

[0029] An output component configured as one of a gear, a worm wheel, and a worm, for fixedly connecting with the lead screw;

[0030] A speed change unit, respectively meshing with the input component and the output component to constitute at least two speed change stages.

[0031] By adopting the above technical solution, the speed change unit with at least two speed change stages enables better speed change effect and more stable operation.

[0032] Optionally, the linear actuator further includes a housing for accommodating the first force transmission chain and the second force transmission chain.

[0033] By adopting the above technical solution, the first force transmission chain and the second force transmission chain are arranged in the housing, and the first force transmission chain and the second force transmission chain are well protected, while facilitating the installation and support of the first force transmission chain and the second force transmission chain.

[0034] Optionally, the linear actuator further includes a partition fixedly connected with the housing. The first force transmission chain is accommodated between the partition and the first side of the housing, and the second force transmission chain is accommodated between the partition and the second side of the housing opposite to the first side.

[0035] By adopting the above technical solution, the partition serves as an intermediate support, making the installation positions of the first force transmission chain and the second force transmission chain more stable.

[0036] Optionally, the planetary gear reduction mechanism further includes:

[0037] A sun gear drivingly connected with the output end of the motor;

[0038] A planetary gear meshing between the sun gear and the internal gear;

[0039] A carrier serving as the output end, for carrying the planetary gear;

[0040] When the internal gear ring is locked against rotation by the clutch, the power of the motor is output through the cage with speed reduction and torque increase.

[0041] When the internal gear ring is released by the clutch, the load torque is released through the freely rotating internal gear ring.

[0042] By adopting the above technical solution, during normal operation, the internal gear ring is locked against rotation by the clutch, and the power of the motor is output through the cage with speed reduction and torque increase; when released, the internal gear ring is released. At this time, due to the braking torque of the motor itself, the sun gear cannot rotate, and the load torque is transmitted to the internal gear ring through the cage and the planet gears, and the internal gear ring rotates to release the load torque.

[0043] 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 relative axial movement and relative circumferential fixation between the two. The movable sleeve engages with the internal gear ring to implement anti-rotation locking. The release component drives the movable sleeve to disengage from the internal gear ring, and the movable sleeve is biased by the biasing element to maintain the engagement tendency with the internal gear ring.

[0044] By adopting the above technical solution, the anti-rotation and unlocking of the internal gear ring are realized by the engagement or disengagement of the movable sleeve that axially moves relative to the fixed sleeve with the internal gear ring, 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 internal gear ring, ensuring normal operation.

[0045] Optionally, the engagement between the movable sleeve and the internal gear ring is set to be one of ratchet fit, spline fit and axial hole and pin fit.

[0046] By adopting the above technical solution, one of ratchet fit, spline fit and axial hole and pin fit can restrict the anti-rotation of the movable sleeve and the internal gear ring in at least one direction, and the structure is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic structural diagram of the present invention.

[0048] Figure 2 is a schematic sectional structural diagram of the present invention.

[0049] Figure 3 is a schematic structural diagram of the present invention with the external housing omitted.

[0050] Figure 4 is a schematic sectional structural diagram of the motor side of the present invention.

[0051] Figure 5 is a schematic sectional structural diagram of the planet gear set of the present invention.

[0052] Figure 6 It is an explosion schematic diagram of the present invention.

[0053] Figure 7 It is an explosion schematic diagram of the planetary gear set of the present invention.

[0054] Figure 8 It is a structural schematic diagram of the clutch and the internal gear ring of the present invention.

[0055] Figure 9 It is a structural schematic diagram of the torsion spring brake of the present invention.

[0056] Figure 10 It is a schematic diagram of the force transmission chain direction of other embodiments of the present invention.

[0057] Figure 11 It is a structural schematic diagram of the cross-section of other embodiments of the present invention.

[0058] Explanation of reference numerals:

[0059] 10. Outer tube; 11. Upper shell; 12. Lower shell; 13. Housing; 14. Motor cover; 15. Partition board; 16. Top bearing;

[0060] 20. Tubular telescopic member;

[0061] 30. Telescopic drive mechanism; 31. Lead screw; 32. Transmission nut;

[0062] 40. Variable speed transmission mechanism; 41. Three-stage straight teeth; 42. Central transmission shaft; 43. Second-stage second straight teeth; 44. Second-stage first straight teeth; 45. First-stage straight teeth;

[0063] 50. Motor;

[0064] 60. Planetary gear reduction mechanism; 61. Cage; 611. Main cage; 612. Planetary gear shaft; 613. Base plate; 614. Snap ring; 62. Planetary gear; 63. Sun gear; 64. Internal gear ring; 640. Locking spline groove; 641. Radial guide block; 65. Brake block; 650. Radial guide groove; 66. Brake housing; 661. Installation insert;

[0065] 70. Clutch; 71. Movable sleeve; 711. Sliding spline; 712. Annular stop; 713. Locking spline; 72. Fixed sleeve; 73. Compression spring;

[0066] 80. Torsion spring brake; 81. First torsion spring seat; 82. Brake torsion spring; 83. Second torsion spring seat; 84. Friction element;

[0067] 90. Release component; 91. Connecting rod; 911. Outer screw; 92. Operating rod; 93. Poking rod;

[0068] 100, the first force transmission chain;

[0069] 200, the second force transmission chain;

[0070] 300, the third force transmission chain;

[0071] a, the first force transmission direction; b, the second force transmission direction; c, the third force transmission direction. Detailed implementation mode

[0072] The following is combined with the attached Figures 1-11 to further elaborate on the present invention in detail.

[0073] Embodiment 1: Disclose a linear actuator. Refer to Figures 1-3 , including an outer tube 10, a housing 13, a motor 50, a tubular telescopic member 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 on the housing 13 by bolts; the first force transmission chain 100 and the second force transmission chain 200 are arranged inside the housing 13; the third force transmission chain 300 is arranged on the housing 13; the outer tube 10 is fixed on the housing 13; the tubular telescopic member 20 is telescopically arranged inside 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 member 20 to perform linear motion. When the tubular telescopic member 20 extends, 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.

[0074] Refer to Figures 1-4, the housing 13 includes an upper housing 11, a lower housing 12 and a partition 15; the upper housing 11 and the lower housing 12 are assembled by screws to form a transmission box with a hollow interior; the outer tube 10 is fixed to the end face of the upper housing 11 away from the lower housing 12 by screws; the partition 15 is fixed inside the upper housing 11 by screws; the first force transmission chain 100 is located between the partition 15 close to the motor 50 and the upper housing 11; the second force transmission chain 200 is located between the partition 15 away from the motor 50 and the lower housing 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 larger length of the first force transmission chain 100 and the third force transmission chain 300, rather than 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 conventional method of setting the motor perpendicular to the lead screw, the first force transmission chain 100 and the third force transmission chain 300 approach each other in a parallel posture. Generally speaking, the motor can directly output torque to the first force transmission chain 100, which makes the axial direction of the output shaft of the motor parallel to the first force transmission direction a, and further makes the motor parallel to the lead screw, reducing the overall volume of the linear actuator and facilitating transportation and installation in small spaces.

[0075] Reference Figure 1 and Figure 3 , in order to protect the motor 50, reference Figure 1 and Figure 2 , a motor cover 14 is sleeved outside the motor 50; the motor cover 14 is fixed to the upper housing 11 by screws.

[0076] Reference Figures 2-7 , 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 cage 61, four planetary gears 62 rotatably connected to the cage 61 and an internal gear ring 64; the sun gear 63 is coaxially arranged inside the internal gear ring 64; the four planetary gears 62 are located between the sun gear 63 and the internal gear ring 64; the planetary gears 62 are respectively meshed with the sun gear 63 and the internal gear ring 64; the end of the output shaft of the motor 50 is in a double-flat position; a slot matching the output shaft of the motor 50 is formed on the end face of the rotating shaft of the sun gear 63 close to the motor 50. The input end of the first force transmission direction a is the sun gear 63, and the output end is the cage 61.

[0077] Reference Figures 2-7, the cage 61 includes a main cage 611 and a cross-shaped bottom plate 613; four connecting through holes are formed on both the main cage 611 and the cross-shaped bottom plate 613; the planet gear 62 is integrally formed with a planet gear shaft 612; both ends of the planet gear shaft 612 pass through the connecting through holes on the corresponding side; two annular groove-shaped clamping grooves are formed at both ends of the planet gear shaft 612; a snap ring 614 is clamped in the clamping groove; a vertically penetrating central through hole is formed at the center of the bottom plate 613; the sun gear 63 passes through the central through hole; during installation, the four planet gear shafts 612 pass through the four central through holes of the main cage 611 in sequence, then the bottom plate 613 is sleeved on the other ends of the four planet gear shafts 612, and finally the snap ring 614 is clamped in the clamping grooves of the four planet gear shafts 612; circular contact rings are formed at both ends of the planet gear 62 coaxially, and the contact rings are in contact with the bottom plate 613 or the main cage 611. Since the area of the contact ring is smaller than the end area of the planet gear 62, such a design can reduce the friction force.

[0078] Reference Figure 2 、 Figure 3 and Figure 5 , the third force transmission chain 300 includes a telescopic driving mechanism 30, and the telescopic driving mechanism 30 includes a lead screw 31 and a transmission nut 32 threadedly engaged with the lead screw; the lead screw 31 is connected to the partition plate 15 through a bearing; the axial direction of the lead screw 31 is parallel to the axial direction of the cage 61. The tubular telescopic member 20 is fixed to the transmission nut 32 by screws. When the tubular telescopic member 20 extends, the third force transmission direction c is the displacement direction of the transmission nut 32 on the lead screw 31, so that the third force transmission direction c is parallel to the first force transmission direction a.

[0079] Reference 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.

[0080] 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.

[0081] 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.

[0082] To sum up, during normal operation, the speed change 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.

[0083] 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.

[0084] 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.

[0085] Reference Figures 4-6 and Figure 8 Figure 8

[0086] The above realizes the anti-rotation of the internal gear ring 64 through the spline fitting method. That is, during normal operation, the internal gear ring 64 cannot rotate, so the power of the motor 50 can be sequentially transmitted to the first-stage straight gear 45 through the sun gear 63, the planetary gear 62, and the cage 61. Therefore, the engagement method between the internal gear ring 64 and the movable sleeve 71 can also be one of ratchet fitting and axial hole pin fitting. When ratchet fitting is used, one of the internal gear ring 64 and the movable sleeve 71 is fixed with a ratchet and the other is rotatably connected with a ratchet tooth. During normal operation, the cooperation between the ratchet and the ratchet tooth makes the internal gear ring 64 unable to rotate forward. When released, the internal gear ring 64 can rotate backward. When axial hole pin fitting is used, one of the internal gear ring 64 and the movable sleeve 71 is formed with a hole that is non-coaxial but axially parallel to both of them, and the other is formed with a pin that cooperates with it.

[0087] Reference Figure 6 and Figure 8, the release member 90 includes a pair of toggle levers 93, a pair of operating levers 92 and a connecting rod 91; the operating levers 92 correspond to the toggle levers 93 one by one; the toggle lever 93 includes an arc-shaped toggle block and a vertical plate portion formed on the outer cylindrical surface of the toggle block; both ends of the operating lever 92 are formed with screw rods; one screw rod of the operating lever 92 is screwed on the vertical plate portion of the toggle lever 93, and the other screw rod vertically passes through the end of the connecting rod 91 and is screwed with a nut; a pair of annular stoppers 712 are formed in the middle of the movable sleeve 71; the toggle blocks of the pair of toggle levers 93 are radially inserted between the pair of annular stoppers 712; the pair of operating levers 92 pass through the lower housing 12 and the connecting rod 91 is located outside the transmission case. In order to reduce friction, the movable sleeve 71 is made of self-lubricating plastic material, ultimately reducing noise.

[0088] In order to facilitate pulling the release member 90, an external screw rod 911 is vertically fixed in the middle of the end face of the connecting rod 91 away from the transmission case; the external screw rod 911 can be used to connect an external handle or a pedal to facilitate driving the release operating member; preferably, the external screw rod 911 is located exactly in the middle of the pair of operating levers 92.

[0089] Of course, the toggle lever 93 may not be translated. The center of the vertical plate portion of the toggle lever 93 is rotatably connected to the transmission case, and then the end of the vertical plate portion of the toggle lever 93 away from the toggle block extends out of the transmission case and is connected to the operating lever 92. In this way, the operating lever 92 drives the toggle lever 93 to rotate, and the toggle block of the toggle lever 93 abuts against and pushes the corresponding annular stopper 712 to drive the movable sleeve 71 to move axially along the fixed sleeve 72; due to the presence of the compression spring 73, there may be only one annular stopper 712 and it is located on the side of the toggle block of the toggle lever 93 away from the internal gear ring 64.

[0090] In addition to the above situation where the release member 90 includes a pair of toggle levers 93 and a pair of operating levers 92, in other embodiments, the number of toggle levers 93 and operating levers 92 of the release member 90 can be more than two, so that during the movement of the movable sleeve 71, it will not be biased as in the case of single fork drive due to the eccentric force on the movable sleeve 71. In this way, there is no need for a high matching accuracy between the movable sleeve 71 and the fixed sleeve 72 to achieve precise guidance, thereby reducing the processing cost.

[0091] Working principle of the first embodiment: During normal operation, one end of the central clutch ring of the movable sleeve 71 is inserted into one end of the internal gear ring 64. At this time, the locking spline 713 is located in the locking spline groove 640 of the internal gear ring 64. Since the movable sleeve 71 is axially slidably arranged in the fixed sleeve 72 and the fixed sleeve 72 is fixedly connected to the partition plate 15, the internal gear ring 64 is locked at this time and cannot rotate; the motor 50 drives the sun gear 63 to rotate, and the sun gear 63 drives the four planet gears 62 to rotate around their own axes. Due to the action of the fixed internal gear ring 64, the four planet gears 62 drive the cage 61 to rotate around its own axis, thereby driving the first-stage straight gear 45 to rotate. Then, through the second-stage first straight gear 44, the second-stage second straight gear 43, and the third-stage straight gear 41, the lead screw 31 of the third transmission chain 300 is driven to rotate. The transmission nut 32 of the third transmission chain 300 moves axially along the outer tube 11, thereby driving the tubular telescopic member 20 to extend.

[0092] 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 internal gear ring 64 restrict the rotation of the planet gears 62, so that the cage 61 cannot rotate, and thus the electric lifting linear actuator cannot contract; at this time, the connecting rod 91 is pulled, and through a pair of operating rods 92 and the axial movement of the movable sleeve 71, the movable sleeve 71 is moved away from the internal gear ring 64, so that the locking spline 713 is disengaged from the locking spline groove 640. In this way, the internal gear ring 64 is unlocked and can rotate freely. Due to the self-weight of the load, the tubular telescopic member 20 is driven to retract, that is, the transmission nut 32 returns to its original position, which drives the lead screw 31 to rotate in the reverse direction. Then, through the third-stage straight gear 41, the second-stage second straight gear 43, the second-stage first straight gear 44, and the first-stage straight gear 45 in sequence, the cage 61 is driven to rotate, thereby realizing the release. At the same time, the internal gear ring 64 is driven by the planet gears 62 to rotate.

[0093] The second embodiment: The difference between the second embodiment and the first embodiment lies in: Refer to Figure 5 and Figure 6, further comprising a centrifugal brake; the centrifugal brake is connected to the internal gear ring 64, and only when the internal gear ring 64 rotates, the centrifugal brake will generate a braking force to balance the load torque applied to the first power transmission chain 100; combining with the first embodiment, when the tubular telescopic member 20 extends out, the internal gear ring 64 is restricted and cannot rotate at this time, so the centrifugal brake will not be triggered. The power of the motor 50 sequentially passes through the sun gear 63, four planet gears 62, the cage 61, the second power transmission chain 200 and the third power transmission chain 300, and the third power transmission chain 300 outputs with deceleration and increased torque. During this process, the centrifugal brake does not work; when the motor 50 loses power and the internal gear ring 64 is released, the load torque sequentially passes through the third power transmission chain 300, the second power transmission chain 200, the cage 61, the planet gear 62 and the four planet gears 62 to drive the internal gear ring 64 to rotate. The rotating internal gear ring 64 triggers the centrifugal brake, and the centrifugal brake generates a centrifugal braking force to balance the load torque.

[0094] Reference Figure 5 , the centrifugal brake includes a rotating member and a brake housing 66; the rotating member is integrally formed on the outer peripheral surface of the internal gear ring 64 and they are coaxially arranged; the internal gear ring 64 is located inside the brake housing 66 and they are coaxially arranged; there is a gap between the rotating member and the brake housing 66, and six fan-shaped brake blocks 65 are arranged in this gap.

[0095] Reference Figure 5 , wherein six radially guiding blocks 641 are formed on the outer peripheral surface of the rotating member and are evenly distributed circumferentially; the radially guiding blocks 641 correspond to the brake blocks 65 one by one; a radially guiding groove 650 that cooperates with the radially guiding block 641 is formed in the middle of the inner surface of the brake block 65 close to the internal gear ring 64; the radially guiding groove 650 is radially sleeved on the corresponding radially guiding block 641; the brake block 65 can move radially in the gap between the rotating member and the brake housing 66. Of course, the radially guiding block 641 can also be arranged on the inner side surface of the brake block 65, and the radially guiding groove 650 can be arranged on the outer peripheral surface of the rotating member; in other embodiments, six guiding grooves can also be formed on the outer cylindrical surface of the rotating member, and the brake block 65 moves radially in the guiding grooves. The above structures all drive the brake block 65 to rotate together with the rotating internal gear ring 64, so that the brake block 65 generates a centrifugal force and moves radially outwards to friction with the brake housing 66 to generate a braking force.

[0096] In addition, the brake block 65 does not have to use the above-mentioned radial guiding method. One end of the brake block 65 is hinged to the outer peripheral surface of the rotating member, and the other end is in a free state. When the brake block 65 is subjected to a centrifugal force, the free end of the brake block 65 can abut against the inner peripheral surface of the brake housing 66 to generate a reverse braking force.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] Embodiment 3: The difference between Embodiment 3 and Embodiment 1 is: Figure 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.

[0101] 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.

[0102] 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 Figure 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.

[0103] Embodiment 4: The difference between Embodiment 4 and Embodiment 2 is: Figure 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 .

[0104] 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: A motor; A tubular telescopic member; A force transmission chain configured to transmit the power of the motor to the tubular telescopic member to drive the tubular telescopic member to perform a linear motion; Characterized in that: the force transmission chain includes a planetary gear reduction mechanism drivingly connected to the output end of the motor; A clutch that rotationally locks the internal gear ring of the planetary gear reduction mechanism; A release member including at least two groups of operating rods and fork levers circumferentially distributed along the clutch; the fork levers are axially translated or rotated under the traction of the operating rods, and are used to drive the clutch to release the internal gear ring to activate the release function of the linear actuator; all the operating rods are connected by connecting rods and can be synchronously tractioned.

2. The linear actuator according to claim 1, wherein: An annular stop is provided along the circumference of the clutch, and the fork lever has an arc-shaped block, and the block axially abuts against the annular stop to drive the clutch.

3. The linear actuator according to claim 1, characterized in that: The force transmission chain includes: A first force transmission chain including the planetary gear reduction mechanism; A second force transmission chain drivingly connected to the first force transmission chain, including a speed change transmission mechanism having gears and / or worm gears; A third force transmission chain drivingly connected to the second force transmission chain, including a lead screw and a transmission nut threadedly engaged with the lead screw, and the transmission nut is connected to the tubular telescopic member; 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 lead screw; 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.

4. A linear actuator according to claim 3, 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.

5. A linear actuator according to claim 3, characterized in that: The speed change transmission mechanism includes: An input member configured as one of a gear, a worm wheel, and a worm, and is used to drivingly connect with the planet carrier of the planetary gear reduction mechanism; An output member configured as one of a gear, a worm wheel, and a worm, and is used to fixedly connect with the lead screw; A speed change unit that meshes with the input member and the output member respectively to form at least two speed change stages.

6. A linear actuator according to claim 3, wherein: The linear actuator further includes a housing that houses the first force transmission chain and the second force transmission chain.

7. A linear actuator according to claim 6, characterized in that: The linear actuator further includes a partition fixedly connected to the housing. The first force transmission chain is housed between the partition and the first side of the housing, and the second force transmission chain is housed between the partition and the second side of the housing opposite to the first side.

8. A linear actuator according to claim 1, characterized in that: The planetary gear reduction mechanism further includes: A sun gear drivingly connected to the output end of the motor; Planetary gears meshing between the sun gear and the internal gear ring; A carrier as the output end for carrying the planetary gears; When the internal gear ring is rotationally locked by the clutch, the power of the motor is output through the carrier with speed reduction and torque increase; When the internal gear ring is released by the clutch, the load torque is released through the freely rotating internal gear ring.

9. 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 relative axial movement and relative circumferential fixation therebetween. The movable sleeve is engaged with the internal gear ring to implement anti-rotation locking. The release member drives the movable sleeve to disengage from the internal gear ring. The movable sleeve is biased by the biasing element to maintain a tendency to engage with the internal gear ring.

10. A linear actuator according to claim 9, characterized in that: The engagement between the movable sleeve and the internal gear ring is configured as one of a ratchet fit, a spline fit, and an axial pin fit.

Images