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 first force transmission chain comprises a planet wheel speed reducing mechanism in transmission connection with the output end of the motor and a centrifugal brake in transmission connection with the output end of the planet wheel speed reducing mechanism; the second force transmission chain is in transmission connection with the output end of the centrifugal brake; the third force transmission chain is in transmission connection with the second force transmission chain and 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. According to the linear actuator, 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 utility model relates to the field of linear actuators, in particular to a linear actuator. Background Art

[0002] Linear actuators, also known as electric push rods, are widely used in furniture, medical equipment, solar power generation and other fields. Their main structure includes a drive motor, an intermediate transmission mechanism, a lead screw, and a transmission nut. The working principle is that the drive motor is started 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. The transmission nut is generally connected to a tubular telescopic component, thereby realizing the telescopic movement of the tubular telescopic component; the intermediate transmission mechanism includes a planetary gear reduction mechanism, and the planetary gear reduction mechanism acts as a reducer.

[0003] For existing linear actuators on the market, after being released, the load will drive the tubular telescopic component to contract, and the contraction speed of the tubular telescopic component is proportional to the load. When the load is very large, the tubular telescopic component will contract very quickly, which will cause impact on the entire linear actuator and cause harm to the user. Utility Model Content

[0004] In order to overcome the deficiencies in the prior art, the utility model provides a linear actuator having the advantage of stable contraction.

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

[0006] A linear actuator comprising:

[0007] Motor;

[0008] Tubular telescopic member;

[0009] 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;

[0010] The force transmission chain comprises:

[0011] The first force transmission chain includes: a planetary gear reduction mechanism drivingly connected to the output end of the motor, and a centrifugal brake drivingly connected to the output end of the planetary gear reduction mechanism;

[0012] A second force transmission chain drivingly connected to the output end of the centrifugal brake, comprising a speed transmission mechanism having gears and / or worm gears;

[0013] 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;

[0014] 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.

[0015] By adopting the above technical scheme, when the tubular telescopic component is extended, the power of the motor drives the tubular telescopic component to perform linear motion through the first force transmission chain, the second force transmission chain and the third force transmission chain in sequence. When the tubular telescopic component is retracted, the load torque is transmitted through the third force transmission chain, the second force transmission chain and the first force transmission chain in sequence. Due to the existence of the centrifugal brake on the first force transmission chain, a braking force is generated to balance the load torque, so that the retraction speed of the tubular telescopic component will not be too fast and the retraction is stable. In addition, the output end of the motor is 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 parallel to the axial direction of the output end of the motor and the force transmission direction of the third force transmission chain where the lead screw is located are not perpendicular to each other, so as to avoid the situation where the output shaft of the motor and the lead screw are perpendicular to each other, reduce the overall volume of the linear actuator, and facilitate transportation and installation.

[0016] Optionally, the force transmission direction of the first force transmission chain is from the input end of the planetary gear reduction mechanism to the output end of the centrifugal brake;

[0017] 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;

[0018] The force transmission direction of the third force transmission chain is the displacement direction of the transmission nut on the screw rod;

[0019] 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.

[0020] 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.

[0021] Optionally, the first force transmission chain and the third force transmission chain are located on the same side of the second force transmission chain.

[0022] By adopting the above technical solution, when the first force transmission chain and the third force transmission chain are 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. Therefore, the overall length of the linear actuator is greatly reduced.

[0023] Optionally, the first force transmission chain further includes a clutch and a release component;

[0024] The clutch is disposed between the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake;

[0025] The release component drives the clutch to cut off the power transmission between the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake to activate the release function of the linear actuator.

[0026] By adopting the above technical solution, during normal operation, the clutch is in driving connection with the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake. In this way, the power of the motor can be transmitted to the lead screw through the planetary gear reduction mechanism, the clutch, the centrifugal brake, and the second force transmission chain. The lead screw drives the tubular telescopic component to perform linear motion. During this process, through multiple decelerations and torque increases by the planetary gear reduction mechanism and the variable speed transmission mechanism, the deceleration effect and the torque increase effect are good; before release, due to the braking torque existing in the motor itself, the planetary gear reduction mechanism cannot move; when the release component drives the clutch to cut off the power between the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake, the immovable planetary gear reduction mechanism will no longer play a braking role, and the linear actuator is released. The lead screw can rotate in reverse, and at the same time, the load torque will only be transmitted to the centrifugal brake and will not be transmitted to the planetary gear reduction mechanism. The planetary gear reduction mechanism will not participate in the subsequent work, thereby reducing wear and increasing the service life.

[0027] Optionally, the centrifugal brake includes:

[0028] A rotating component, which is in driving connection between the clutch and the input end of the second force transmission chain;

[0029] A brake housing, which provides a braking friction surface;

[0030] A brake block disposed between the rotating component and the brake housing, which generates centrifugal motion by means of the rotational motion of the rotating component and contacts the braking friction surface.

[0031] By adopting the above technical solution, the centrifugal brake 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.

[0032] 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;

[0033] 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;

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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 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; at the same time, the centrifugal brake and the torsion spring brake are used in combination to achieve a better braking effect.

[0038] Optionally, the rotating component includes a connecting shaft and a clutch seat that are engaged with each other; the clutch seat is engaged with the clutch; and the connecting shaft is drivingly connected to the input end of the second force transmission chain.

[0039] By adopting the above technical solution, the rotating component is split into two components: a connecting shaft and a clutch seat, which is convenient for subsequent replacement and maintenance.

[0040] The clutch includes a movable sleeve and a biasing element. The connection between the movable sleeve and the output end of the planetary gear reduction mechanism allows axial relative movement and circumferential relative fixation between the two. The release member drives the movable sleeve away from the input end of the centrifugal brake, and the movable sleeve is biased by the biasing element to maintain a tendency to engage with the input end of the centrifugal brake.

[0041] By adopting the above technical solution, the rotation stop and unlocking of the internal gear ring are achieved by engaging or disengaging the movable sleeve that axially moves relative to the output end of the planetary gear reduction mechanism. The structure is simple, and the locking and unlocking operations are convenient. At the same time, the presence of the biasing element makes it difficult for the movable sleeve to disengage from the output end of the planetary gear reduction mechanism, ensuring normal operation.

[0042] Optionally, the engagement between the movable sleeve and the input end of the centrifugal brake is set to be one of ratchet fit, spline fit, axial hole and pin fit, and non-circular shaft and hole fit.

[0043] By adopting the above technical solution, one of ratchet fit, spline fit, axial hole and pin fit, and non-circular shaft and hole fit can restrict the rotation stop of the movable sleeve and the internal gear ring in at least one direction, and the structure is simple.

[0044] Optionally, the release member includes an operating rod and a lever. The lever is axially translated or rotated under the traction of the operating rod, and is used to drive the clutch away from the input end of the centrifugal brake.

[0045] By adopting the above technical solution, the lever drives the clutch to axially move for disengagement, with a simple structure and convenient operation.

[0046] Optionally, an annular stop is provided along the circumference of the clutch. The lever has an arc-shaped block, and the block axially pushes against the annular stop to drive the clutch.

[0047] By adopting the above technical solution, the annular stop cooperates with the arc-shaped block of the lever, with simple machining and convenient connection.

[0048] Optionally, the release member includes at least two groups of operating rods and levers distributed along the circumference of the clutch, and all the operating rods are connected by a connecting rod and can be synchronously tractioned.

[0049] By adopting the above technical solution, all the operating rods and levers distributed along the circumference of the clutch can be synchronously moved through the connecting rod, with convenient operation. In addition, the cooperation of multiple levers and the clutch makes the relative position between the two more stable, so that the moving direction of the driven clutch is more accurate.

[0050] 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.

[0051] 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.

[0052] 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;

[0053] 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;

[0054] 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.

[0055] 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.

[0056] Optionally, one of the internal gear and the retaining frame of the planetary gear reduction mechanism serves as an output end.

[0057] By adopting the above technical solution, the internal gear and the retaining frame of the planetary gear reduction mechanism can both be used as output ends. When the retaining frame is used as the output end, the internal gear is fixed; when the internal gear is used as the output end, the internal gear rotates freely; this provides a wider range of solution options.

[0058] Optionally, the speed transmission mechanism includes:

[0059] An input component configured as one of a gear, a worm wheel, and a worm, and configured to be fixedly connected to the centrifugal brake;

[0060] An output component configured as one of a gear, a worm wheel, and a worm, and used for fixed connection with the lead screw;

[0061] A speed change unit meshes with the input component and the output component respectively to form at least two speed change stages.

[0062] By adopting the above technical solution, the speed change unit with at least two speed change stages has a better deceleration effect, thereby further increasing the torque of the lead screw and enabling the lead screw to have a greater thrust. Description of the Drawings

[0063] Figure 1 is a schematic structural diagram of the present utility model.

[0064] Figure 2 is a schematic structural diagram of the cross-section of the present utility model.

[0065] Figure 3 is of the present utility model Figure 2 schematic structural diagram of the partial enlargement.

[0066] Figure 4 is a schematic structural diagram of the present utility model with the external housing omitted.

[0067] Figure 5 is an explosion schematic diagram of the present utility model.

[0068] Figure 6 is an explosion schematic diagram of the internal gear ring, movable sleeve and centrifugal brake of the present utility model.

[0069] Figure 7 is an explosion schematic diagram of the internal gear ring, movable sleeve and centrifugal brake of the present utility model.

[0070] Figure 8 is a schematic structural diagram of the cross-section of the planetary gear reduction mechanism of the present utility model.

[0071] Figure 9 is an explosion structural diagram of the planetary gear reduction mechanism of the present utility model.

[0072] Figure 10 is an explosion structural diagram of the centrifugal brake of the present utility model.

[0073] Figure 11 is a schematic structural diagram of the torsion spring brake of the present utility model.

[0074] Figure 12 is a schematic diagram of the force transmission chain direction of other embodiments of the present utility model

[0075] Description of the Reference Numerals:

[0076] 10. Outer tube; 11. Upper shell; 12. Lower shell; 13. Housing; 14. Positioning plate; 15. Support plate;

[0077] 20. Tubular telescopic member;

[0078] 30. Telescopic drive mechanism; 31. Lead screw; 32. Transmission nut;

[0079] 40. Variable speed transmission mechanism; 41. Three-stage spur gear; 42. Central transmission shaft; 43. Second spur gear of the second stage; 44. First spur gear of the second stage; 45. First-stage spur gear;

[0080] 50. Motor;

[0081] 60. Planetary gear reduction mechanism; 61. Sun gear; 62. Cage; 63. Planetary gear shaft; 64. Planetary gear; 65. Internal gear ring; 651. Slip ring seat; 6510. Spline groove of the internal gear ring; 66. Spacer ring; 67. Snap ring;

[0082] 70. Release mechanism; 71. Movable sleeve; 711. Clutch support ring; 7110. Lever slot; 712. First connecting ring; 7121. First spline; 713. Second connecting ring; 7131. Second spline; 72. Compression spring; 73. Lever; 74. Operating lever;

[0083] 80. Centrifugal brake; 81. Clutch seat; 810. Connecting spline groove; 811. Limit ring plate; 812. Radial guide block; 814. Spline groove of the clutch seat; 82. Brake block; 820. Radial guide groove; 83. Brake housing; 84. Connecting shaft; 841. Connecting main seat; 842. Connecting column; 843. Connecting spline;

[0084] 90. Torsion spring brake; 91. First torsion spring seat; 92. Brake torsion spring; 93. Second torsion spring seat; 94. Friction element;

[0085] 100. First power transmission chain;

[0086] 200. Second power transmission chain;

[0087] 300. Third power transmission chain;

[0088] a. First power transmission direction; b. Second power transmission direction; c. Third power transmission direction. Detailed implementation mode

[0089] The following is a further detailed description of the present utility model in conjunction with the attached Figure 1-12 figures.

[0090] 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 to the housing 13 by bolts; the first force transmission chain 100 and the second force transmission chain 200 are disposed inside the housing 13; the third force transmission chain 300 is disposed on the housing 13; the outer tube 10 is fixed to the housing 13; the tubular telescopic member 20 is telescopically disposed 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 a 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.

[0091] Reference Figures 1-3 , the housing 13 includes an upper shell 11, a lower shell 12, a positioning plate 14, and a support plate 15; the upper shell 11 and the lower shell 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 shell 11 away from the lower shell 12 by screws; the support plate 15 is fixed inside the lower shell 12 by screws; the positioning plate 14 is fixed inside the upper shell 11 by screws; the positioning plate 14 and the support plate 15 are arranged in parallel; the first force transmission chain and the second force transmission chain are located between the support plate 15 close to the motor 50 and the upper shell 11; the first force transmission chain and the third force transmission chain 30 are located on the same side of the support plate 15 and their force transmission directions 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. Therefore, 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. The overall volume of the linear actuator is reduced, facilitating transportation and installation in small spaces.

[0092] Reference Figure 2 , the first force transmission chain 100 includes a planetary gear reduction mechanism 60, a release mechanism 70, and a centrifugal brake 80.

[0093] Reference Figure 3 and Figure 8, the planetary gear reduction mechanism 60 includes a sun gear 61, a cage 62, four planetary gears 64 rotatably connected to the cage 62, and an internal gear ring 65; the sun gear 61 is coaxially arranged inside the internal gear ring 65; the four planetary gears 64 are located between the sun gear 61 and the internal gear ring 65; the planetary gears 64 are respectively meshed with the sun gear 61 and the internal gear ring 65; the end of the output shaft of the motor 50 has 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 61 close to the motor 50.

[0094] Reference Figure 9 , the cage 62 is cross-shaped; vertical through rotating connection holes are respectively formed at the four ends and the center of the cage 62; a planetary gear shaft 63 is axially penetrated through the middle of the planetary gear 64; ring-shaped clamping grooves are formed at both ends of the planetary gear shaft 63; one end of the planetary gear shaft 63 passes through the rotating connection hole at the end of the cage 62 and a snap ring 67 is installed in its clamping groove; a spacer ring 66, a planetary gear 64 and a spacer ring 66 are sequentially sleeved on the end of the planetary gear shaft 63 away from the cage 62 and a snap ring 67 is installed in the clamping groove at the end; the end of the planetary gear shaft 63 away from the cage 62 is rotatably connected to the upper shell 11; the sun gear 61 is integrally formed with a sun gear shaft; a ring-shaped clamping groove is formed at the end of the sun gear shaft away from the sun gear 61; the sun gear shaft passes through the rotating connection hole at the center of the cage 62 and a snap ring 67 is installed in the clamping groove at the end; a spacer ring 66 is sleeved on the sun gear shaft and both ends of this spacer ring 66 respectively contact the sun gear 61 and the cage 62. Since the area of the spacer ring 66 is smaller than the end area of the planetary gear 64 or the sun gear 61, such a design can reduce friction.

[0095] Reference Figure 2 and Figure 3 , the main body of the internal gear ring 65 is a cylinder with one end open and teeth are formed on the inner cylindrical surface; the cage 62, the planetary gears 64 and the sun gear 61 are located inside the opening of the main body of the internal gear ring 65; the internal gear ring 65 is rotatably connected to the side wall of the upper shell 12 away from the lower shell 13 through a bearing; in order to reduce weight, a coaxial through top hole is formed on the top surface of the main body of the internal gear ring 65.

[0096] Reference Figures 2-7, the release mechanism 70 includes a clutch and a release component; the clutch includes a movable sleeve 71 and six compression springs 72; the movable sleeve 71 includes an annular clutch support ring 711; one end of the clutch support ring 711 is formed with a coaxially arranged annular first connection ring 712, and the other end is formed with a coaxially arranged annular second connection ring 713; the inner diameters of the second connection ring 713 and the first connection ring 712 are the same as the inner diameter of the clutch support ring 711, and the outer diameters are both smaller than the outer diameter of the clutch support ring 711; eight first splines 7121 evenly distributed in the circumferential direction are formed on the outer cylindrical surface of the first connection ring 712; one end of the first spline 7121 is fixed to the clutch support ring 711; six second splines 7131 evenly distributed in the circumferential direction are formed on the outer cylindrical surface of the second connection ring 713; one end of the second spline 7131 is fixed to the clutch support ring 711; an annular sliding ring seat 651 coaxially arranged is formed on the end face of the internal gear ring 65 close to the movable sleeve 71; six internal gear ring spline grooves 6510 respectively mating with the second splines 7131 are formed on the inner cylindrical surface of the sliding ring seat 651; the compression springs 72, the internal gear ring spline grooves 6510 and the second splines 7131 are in one-to-one correspondence; the second splines 7131 are slidably arranged in the internal gear ring spline grooves 6510 on the corresponding side; the compression springs 72 are located in the internal gear ring spline grooves 6510 on the corresponding side, one end abuts against the bottom surface of the internal gear ring spline groove 6510 on the corresponding side, and the other end abuts against the second spline 7131 on the corresponding side; the function of the compression spring 72 is to bias the movable sleeve 71 towards the centrifugal brake 80, so that the movable sleeve 71 is not easily separated from the centrifugal brake 80, ensuring the normal transmission of the motor power; in order to prevent the compression spring 72 from shifting, spring slots into which the compression spring 72 is inserted are respectively formed on the bottom surface of the internal gear ring spline groove 6510 and the end face of the second spline 7131 close to the internal gear ring spline groove 6510, and both ends of the compression spring 72 are respectively located in the spring slots on the corresponding side, so that the compression spring 72 is not easily shifted.

[0097] The above realizes the connection between the movable sleeve 71 and the internal gear ring 65 through spline fitting. That is, during normal operation, the power of the motor 50 can be transmitted to the second force transmission chain successively through the sun gear 61, the planet gear 62, the internal gear ring 65, the movable sleeve 71 and the centrifugal brake 80. Of course, the engagement mode between the internal gear ring 65 and the movable sleeve 71 can be one of ratchet fitting, axial hole pin fitting and non-circular shaft hole fitting. When ratchet fitting is used, one of the internal gear ring 65 and the movable sleeve 75 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 65 unable to rotate forward. When released, the internal gear ring 65 can rotate backward. When axial hole pin fitting is used, one of the internal gear ring 65 and the movable sleeve 74 is formed with a hole that is non-coaxial and axially parallel to both of them, and the other is formed with a pin that cooperates with it. When non-circular shaft hole fitting is used, one of the internal gear ring 65 and the movable sleeve 74 is formed with a coaxial non-circular hole, and the other is formed with a non-cylindrical pin that cooperates with it, such as a square columnar pin.

[0098] In this embodiment, the internal gear ring 65 is freely rotatably arranged, and the internal gear ring 65 is the output end of the planetary gear reduction mechanism 60. In other embodiments, the internal gear ring 65 can also be fixed, and then the cage 62 is used as the output end of the planetary gear reduction mechanism 60, and then the movable sleeve 75 is axially slidably connected relative to the cage 62. The connection mode between the movable sleeve 75 and the cage 62 can refer to the connection mode between the movable sleeve 75 and the internal gear ring 65.

[0099] Reference Figures 2-7 , a shift lever slot 7110 in the shape of an annular groove is formed on the outer cylindrical surface in the middle of the clutch support ring 711, so that both axial sides of the shift lever slot 7110 are formed as annular stops; the release component includes a shift lever 73 and an operating lever 74; the shift lever 73 includes an arc-shaped shift block and a vertical plate portion formed on the outer cylindrical surface of the shift block; a square groove-shaped operation limit groove 121 is formed by the side wall of the upper shell 12 away from the telescopic drive mechanism 30 protruding outward; the operating lever 74 is axially inserted into the operation limit groove 121 and both ends of the operating lever 74 extend out of the operation limit groove 121. The axial direction of the operating lever 74 is parallel to the axial direction of the movable sleeve 71; the shift block of the shift lever 73 is radially inserted into the shift lever slot 7110, and the vertical plate portion is screwed onto the operating lever 74. In order to reduce the friction between the movable sleeve 71 and the shift lever 73, the movable sleeve 71 is made of self-lubricating plastic material, and finally the noise is reduced.

[0100] Of course, the lever 73 may not translate. The center of the vertical plate portion of the lever 73 is rotatably connected to the transmission case, and then the end of the vertical plate portion of the lever 73 away from the shifting block extends out of the transmission case and is connected to the operating lever 72. In this way, the operating lever 74 drives the lever 73 to rotate, and the shifting block of the lever 73 abuts against and pushes the corresponding annular stopper, thereby driving the movable sleeve 71 to move axially along the internal gear ring 65. Due to the presence of the compression spring 72, there may be only one annular stopper and it is located on the side of the shifting block of the lever 73 close to the internal gear ring 65.

[0101] Reference Figure 3 and Figure 5 As shown in FIGS. 7 and 8, the centrifugal brake 80 includes a rotating member, a brake housing 83, and six fan-shaped brake blocks 82. The rotating member includes a connecting shaft 84 and a clutch seat 81 that are engaged with each other. The brake housing 83 is fixed to the positioning plate 14. The clutch seat 81 is located inside the brake housing 83 and they are coaxially arranged. The clutch seat 81 of the rotating member is the input end of the centrifugal brake 80, and the clutch is arranged between the clutch seat 81 and the output end of the planetary gear reduction mechanism. When the tubular telescopic member 20 extends, the movable sleeve 71 of the clutch connects the clutch seat 81 and the output end of the planetary gear reduction mechanism. At this time, the power of the motor passes through the planetary gear reduction mechanism, the movable sleeve 71, the clutch seat 81, the connecting shaft 84, the second power transmission chain 200, and the third power transmission chain 300. The third power transmission chain 300 outputs with reduced speed and increased torque. At this time, since the rotating speed of the rotating member is relatively slow, the brake blocks 82 will not contact the brake housing 83, and thus no frictional braking force will be generated. When the motor 50 loses power, due to the braking torque existing in the motor 50 itself, the output end of the planetary gear reduction mechanism cannot rotate in the reverse direction. At this time, the release member drives the movable sleeve 71 to disengage from the clutch seat 81, thereby cutting off the power transmission between the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake. The load torque can drive the clutch seat 81 to rotate successively through the third power transmission chain 300, the second power transmission chain 200, and the connecting shaft 84. In this way, the release function of the linear actuator is activated. At the same time, the rotating clutch seat 81 drives the brake blocks 82 to move and rotate. The brake blocks 82 move radially outwards due to centrifugal force and contact the brake housing 83 to generate centrifugal braking force to balance the load torque.

[0102] Reference Figure 6 and Figure 7, the clutch seat 81 is in an annular shape; eight clutch seat spline grooves 814 respectively corresponding to the spline grooves of the first spline 7121 are formed at one end of the inner cylindrical surface of the clutch seat 81 close to the movable sleeve 71; the connecting shaft 84 includes a connecting main seat 841 in a stepped cylindrical shape; a flat column-shaped connecting column 842 arranged coaxially is formed at the large-diameter end of the connecting main seat 841; four connecting splines 843 evenly distributed in a circumferential direction are formed at the step of the connecting shaft 84; four connecting spline grooves 810 respectively cooperating with the connecting splines 843 are formed at one end of the inner cylindrical surface of the clutch seat 81 far from the movable sleeve 71; the positioning plate 14 and the connecting main seat 841 of the connecting shaft 84 are rotationally connected through a bearing; a circular hole through which the connecting column 842 passes and rotates is formed on the support plate 15. The input end of the first force transmission direction a is the sun gear 63, and the output end is the connecting shaft 84.

[0103] Reference Figure 5 and Figure 11 , a gap is provided between the clutch seat 81 and the brake housing 83, and six fan-shaped brake blocks 82 are evenly distributed in a circumferential direction within this gap; six radially guiding blocks 812 evenly distributed in a circumferential direction are formed on the outer cylindrical surface of the clutch seat 81; the radially guiding blocks 812 correspond to the brake blocks 82 one by one; a radially guiding groove 820 cooperating with the radially guiding block 812 is formed in the middle of the inner surface of the brake block 82 close to the clutch seat 81; the radially guiding groove 820 is radially sleeved on the corresponding radially guiding block 812; the brake block 82 can move radially within the gap between the clutch seat 81 and the brake housing 83. Of course, the radially guiding block 812 can also be arranged on the inner side surface of the brake block 82, and the radially guiding groove 820 can be arranged on the outer peripheral surface of the rotating part. In other embodiments, six guiding grooves can also be formed on the outer cylindrical surface of the clutch seat 81, and the brake block 82 moves radially within the guiding grooves. The above structures all drive the brake block 82 to rotate together with the rotating clutch seat 81, so that the brake block 82 generates a centrifugal force and moves radially outward to friction with the brake housing 83 to generate a braking force.

[0104] Six partition vertical plates can also be formed on the outer cylindrical surface of the clutch seat 81; the partition vertical plates are located between adjacent brake blocks 82. In addition, the brake block 82 can also not use the above-mentioned radial guiding method. One end of the brake block 82 is hinged to the outer peripheral surface of the rotating part, and the other end is in a free state. When the brake block 82 is subjected to a centrifugal force, the free end of the brake block 82 can abut against the inner peripheral surface of the brake housing 83 to generate a reverse braking force.

[0105] In order to prevent the brake block 82 from shifting, a coaxial annular limiting ring plate 811 is formed at one end of the outer cylindrical surface of the clutch seat 81 close to the movable sleeve 71; the brake block 82 is located between the limiting ring plate 811 and the positioning plate 14.

[0106] Reference Figures 2-6The third force transmission chain 300 includes a telescopic drive mechanism 30; the telescopic drive mechanism 30 includes a screw rod 31 and a transmission nut 32 threadedly engaged with the screw rod; the screw rod 31 is connected to the upper shell 11 and the partition 15 through a bearing; the axial direction of the screw rod 31 is parallel to the axial direction of the inner gear ring 65. The tubular telescopic component 20 is fixed to the transmission nut 32 by screws. 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.

[0107] refer to Figures 2-5 The 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 61 and the output shaft of the motor 50, that is, the connection method through a non-circular hole and a non-cylindrical shaft; one end of the tertiary spur gear 41 is rotatably connected to the upper shell 12 through a bearing, and the other end is rotatably connected to the support plate 15 through a bearing; a central transmission shaft 42 is rotatably connected between the support plate 15 and the positioning plate 14 through a bearing; the secondary spur gear is coaxially fixed to the center On the transmission shaft 42, the secondary spur teeth include the second spur teeth 43 and the first spur teeth 44 connected in one piece; the center of the primary spur teeth 45 is formed with a central connection hole that matches the connection column 842; the connection column 842 is sequentially sleeved with a gasket and the primary spur teeth 45; the connection column 842 is clamped with a snap ring; the primary spur teeth 45 and the gasket are axially limited by the snap ring; the primary spur teeth 45 are meshed with the first spur teeth 44; the second spur teeth 43 are meshed with the third spur teeth 41; the diameter of the primary spur teeth 45 is smaller than the diameter of the first spur teeth 44; the diameter of the second spur teeth 43 is smaller than the diameter of the third spur teeth 41. The input end of the second force transmission direction b is the primary spur teeth 45, and the input end is the third spur teeth 41.

[0108] 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.

[0109] 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 purpose of speed change. At the same time, other common speed change structures may also be used.

[0110] 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 transmission connected to the retaining frame 62; and can select one of the gear, worm wheel and worm as the output component, which is transmission connected to the screw 31.

[0111] Working principle of the first embodiment: During normal operation, the movable sleeve 71 is close to the clutch seat 81 and the first spline 7121 of the movable sleeve 71 is inserted into the clutch seat spline groove 814 of the clutch seat 81, and the second spline 7131 of the movable sleeve 71 is located in the internal gear ring spline groove 6510 of the internal gear ring 65. In this way, the internal gear ring 65, the movable sleeve 71, and the clutch seat 81 are integrated. Thus, the motor 50 drives the sun gear 61 to rotate, the sun gear 61 drives the four planet gears 64 to rotate on their own axes, and the four rotating planet gears 64 drive the internal gear ring 65 to rotate. Through the movable sleeve 71, the clutch seat 81, the connecting shaft 84, and the first-stage spur gear 45 rotate synchronously. Then, through the second-stage first spur gear 44, the second-stage second spur gear 43, and the third-stage spur gear 41, the lead screw 31 of the telescopic drive mechanism 30 is driven to rotate, and the transmission nut 32 of the telescopic drive mechanism 30 moves axially along the outer tube 11, thereby driving the tubular telescopic member 20 to extend.

[0112] When released, the operating rod 74 drives the lever 73 and the movable sleeve 71 to move away from the clutch seat 81 until the first spline 7121 of the movable sleeve 71 disengages from the clutch seat spline groove 814 of the clutch seat 81. At this time, due to the load, the tubular telescopic member 20 retracts, that is, the transmission nut 32 returns to its original position, which drives the lead screw 31 of the telescopic drive mechanism 30 to rotate in the reverse direction. Then, through the third-stage spur gear 41, the second-stage second spur gear 43, the second-stage first spur gear 44, and the first-stage spur gear 45 in sequence, the connecting shaft 84 and the clutch seat 81 are driven to rotate, thus achieving release. In this way, the load torque is not transmitted to the planetary gear reduction mechanism 60, and the components of the planetary gear reduction mechanism 60 do not participate in the work at this time, thereby reducing wear and increasing service life.

[0113] When released, the rotating clutch seat 81 drives the brake block 82 to rotate together. Since the brake block 82 is arranged to move radially, the brake block 82 moves outward due to the centrifugal force and rubs against the brake housing 83 to generate frictional force, thereby playing a role in reverse braking. In this way, the contraction speed of the tubular telescopic member 20 will not be too fast and no impact will be formed. In addition, due to different load magnitudes, the moving speed of the transmission nut 32 is different, and the rotational speed of the lead screw 31 is also different. Thus, the rotational speed of the clutch seat 81 after transmission is also different, that is, the rotational speed of the brake block 82 is also different, and finally different frictional forces are generated; the greater the load, the greater the frictional force and the greater the reverse braking force; the smaller the load, the smaller the frictional force and the smaller the reverse braking force; therefore, a nearly constant release speed can be achieved under different loads.

[0114] Embodiment 2: The difference between Embodiment 2 and Embodiment 1 is that: The release component includes two lever rods 73 and two operating rods 74, and also includes a connecting rod; The block of the lever rod 73 is radially inserted into the lever rod slot 7110 at the same time, and then the operating rod 74 passes through the transmission case. One end of the operating rod 74 is fixedly connected to the vertical plate part of the corresponding side lever rod 73, and the other end is fixedly connected to the connecting rod; During operation, driving the connecting rod can achieve the synchronous movement of the two operating rods 74 and the two lever rods 73, making the driving direction more accurate.

[0115] Except for the case where the above release component includes a pair of lever rods 73 and a pair of operating rods 74, in other embodiments, the number of lever rods 73 and operating rods 74 included in the release component can be more than two, so that during the movement of the movable sleeve 71, it will not show a situation of moving deviation due to the eccentric force of the movable sleeve 71 during single fork drive. In this way, there is no need for a high matching accuracy between the movable sleeve 71 and the clutch seat 81 to achieve precise guidance, thereby reducing the processing cost.

[0116] Embodiment 3: The difference between Embodiment 3 and Embodiment 1 is that: Refer to Figure 11 , the linear actuator further includes a torsion spring brake 90, and the torsion spring brake 90 includes a first torsion spring seat 91, a second torsion spring seat 93, a braking torsion spring 92 and a friction element 94; The first torsion spring seat 91 is connected to one end of the lead screw 31 away from the transmission nut 32. The lead screw 31 rotates synchronously with the first torsion spring seat 91 at the same speed. The connection method between the two can refer to the connection method between the rotating shaft of the sun gear 61 and the output shaft of the motor 50, that is, by connecting a non-circular hole and a non-cylindrical shaft. In this way, the first torsion spring seat 91 is non-rotatably connected to the lead screw 31; The two ends of the braking torsion spring 92 are respectively clamped to the first torsion spring seat 91 and the second torsion spring seat 93; When the first torsion spring seat 91 and the second torsion spring seat 93 rotate relative to each other, the braking torsion spring 92 can be released or tightened; The friction element 84 is fixed to one end of the second torsion spring seat 93 away from the braking torsion spring 92 and abuts against the inner surface of the lower housing 12. During operation, the first torsion spring seat rotates with the lead screw 31 to release the braking torsion spring; When releasing, the first torsion spring seat rotates with the lead screw 31 to tighten the braking 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 housing 12 generate a frictional braking force.

[0117] 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.

[0118] Example 4: Reference Figure 2 In the first embodiment, the first force transmission direction a, the second force transmission direction b and the third force transmission direction c 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; Figure 12 In embodiment 4, 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.

[0119] The above are all preferred embodiments of the present utility model, and are not intended to limit the protection scope of the present utility model. Therefore, any equivalent changes made based on the structure, shape, and principle of the present utility model should be included in the protection scope of the present utility model.

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 comprises: A first force transmission chain, comprising: a planetary gear reduction mechanism drivingly connected to the output end of the motor, and a centrifugal brake drivingly connected to the output end of the planetary gear reduction mechanism; A second force transmission chain drivingly connected to the output end of the centrifugal brake, comprising a speed change transmission mechanism having gears and / or worm gears; A third force transmission chain drivingly connected to the second force transmission chain, comprising a lead screw and a transmission nut threadedly engaged with the lead screw, the transmission nut being connected to the tubular telescopic member; 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.

2. The linear actuator according to claim 1, characterized in that: The force transmission direction of the first force transmission chain is from the input end of the planetary gear reduction mechanism to the output end of the centrifugal brake; 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 directions of the first force transmission chain and 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 first force transmission chain further comprises a clutch and a release member; The clutch is disposed between the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake; The release member drives the clutch to cut off the power transmission between the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake to activate the release function of the linear actuator.

5. A linear actuator according to claim 4, characterized in that: The centrifugal brake comprises: A rotating member drivingly connected between the clutch and the input end of the second force transmission chain; A brake housing providing a braking friction surface; A brake block disposed between the rotating member and the brake housing, generating a centrifugal motion by means of the rotational motion of the rotating member and contacting the braking friction surface.

6. The linear actuator according to claim 5, characterized in that: One of the brake block and the rotating member is provided with a radial guiding groove, and the other is provided with a radial guiding block, and the radial guiding block is inserted into the radial guiding groove to guide the centrifugal motion of the brake block; Alternatively, the outer peripheral surface of the rotating member has a guiding groove adapted to the brake block, the brake block is fitted into the guiding groove, and the brake block rotates synchronously with the rotating member in the circumferential direction and can move radially relative to the rotating member; Alternatively, one end of the brake block is pivotally connected to the rotating member, and the other end constitutes a free end capable of moving radially relative to the rotating member.

7. A linear actuator according to claim 5, characterized in that: The rotating member includes a connecting shaft and a clutch seat engaged with each other; the clutch seat is engaged with the clutch; the connecting shaft is drivingly connected to the input end of the second force transmission chain.

8. A linear actuator according to claim 4, wherein: The clutch comprises a movable sleeve and a biasing element. The connection between the movable sleeve and the output end of the planetary gear reduction mechanism allows the two to move relative to each other axially and to be relatively fixed circumferentially. The release component drives the movable sleeve to disengage from the input end of the centrifugal brake. The movable sleeve is biased by the biasing force of the biasing element and maintains a tendency to engage with the input end of the centrifugal brake.

9. A linear actuator according to claim 8, wherein: The engagement of the movable sleeve with the input end of the centrifugal brake is configured as one of ratchet fit, spline fit, axial hole pin fit and non-circular shaft hole fit.

10. A linear actuator according to claim 4, 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 disengage from the input end of the centrifugal brake.

11. A linear actuator according to claim 10, wherein: 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.

12. A linear actuator according to claim 10, 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.

13. A linear actuator according to claim 1, 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.

14. A linear actuator according to claim 13, 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.

15. A linear actuator according to claim 1, characterized in that: One of the internal gear and the retaining frame of the planetary gear reduction mechanism serves as an output end.

16. 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 fixedly connected to the centrifugal brake; 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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