Linear actuator

Abstract

The invention 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. The situation that the output shaft of the motor is perpendicular to the lead screw is avoided, the overall size of the linear actuator is reduced, and transportation and installation are convenient.

Description

Technical Field

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

[0002] 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 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. 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, which 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. Summary of the invention

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

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[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 located on the same side of the second force transmission chain, the overall length of the linear actuator depends on the relatively larger length of the first force transmission chain and the third force transmission chain, rather than the sum of the lengths of the first force transmission chain and the third force transmission chain, thereby greatly reducing the overall length of the linear actuator.

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

[0024] A clutch, arranged 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 transmission connects the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake, so that the power of the motor can be transmitted to the screw through the planetary gear reduction mechanism, the clutch, the centrifugal brake, and the second force transmission chain. The screw is used for the transmission nut to drive the tubular telescopic component to perform linear motion. In this process, the planetary gear reduction mechanism and the speed change transmission mechanism are used to reduce speed and increase torque for many times, and the deceleration effect and torque increase effect are good; before release, the planetary gear reduction mechanism cannot move due to the braking torque of the motor itself; 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 planetary gear reduction mechanism that cannot move will no longer play a braking role, the linear actuator is released, the screw can be reversed, and at the same time, the load torque will only be transmitted to the centrifugal brake but not to the planetary gear reduction mechanism, and the planetary gear reduction mechanism will not participate in subsequent work, thereby reducing wear and improving service life.

[0027] Optionally, the centrifugal brake comprises:

[0028] A rotating component drivingly connected between the clutch and an input end of the second force transmission chain;

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

[0030] The brake pad disposed between the rotating member and the brake housing generates centrifugal motion due to the rotational motion of the rotating member and contacts the brake friction surface.

[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 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.

[0041] By adopting the above technical solution, the inner gear ring is stopped and unlocked by engaging or disengaging from the output end of the planetary gear reduction mechanism through a movable sleeve that moves axially 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, thereby ensuring normal operation.

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

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

[0044] Optionally, the release component includes an operating rod and a shift rod, and the shift rod is pulled by the operating rod to produce axial translation or rotation, so as to drive the clutch to disengage from the input end of the centrifugal brake.

[0045] By adopting the above technical solution, the lever drives the clutch to move axially to disengage, which has a simple structure and is easy to operate.

[0046] Optionally, an annular stop is provided on the clutch along its circumference, and the shift rod has an arc-shaped shift block, and the shift block axially pushes against the annular stop to drive the clutch.

[0047] By adopting the above technical solution, the annular stopper cooperates with the arc-shaped shifting block of the shifting rod, which is simple to process and convenient to connect.

[0048] Optionally, the release component includes at least two groups of operating rods and shifting rods distributed along the circumference of the clutch, and all the operating rods are connected by connecting rods so as to be pulled synchronously.

[0049] By adopting the above technical solution, all operating rods and levers distributed along the circumference of the clutch can be moved synchronously through the connecting rod, which is easy to operate. In addition, the cooperation between multiple levers and the clutch makes the relative position between the two more stable, thereby making the movement direction of the driven clutch more accurate.

[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 rod 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 change 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] The speed change unit engages the input member and the output member 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 can achieve a better deceleration effect, thereby further increasing the torque of the screw rod and making the screw rod have a greater thrust. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a structural schematic diagram of the present invention.

[0064] Figure 2 It is a schematic structural diagram of the cross section of the present invention.

[0065] Figure 3 The present invention Figure 2 A locally enlarged structural diagram.

[0066] Figure 4 It is a schematic diagram of the structure of the present invention with the external shell omitted.

[0067] Figure 5 It is an exploded schematic diagram of the present invention.

[0068] Figure 6 It is an exploded schematic diagram of the inner gear ring, the movable sleeve and the centrifugal brake of the present invention.

[0069] Figure 7 It is an exploded schematic diagram of the inner gear ring, the movable sleeve and the centrifugal brake of the present invention.

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

[0071] Fig. 9 It is a schematic diagram of the exploded structure of the planetary gear reduction mechanism of the present invention.

[0072] Fig.10 It is a schematic diagram of the explosion structure of the centrifugal brake of the present invention.

[0073] Fig.11 It is a structural schematic diagram of the torsion spring brake of the present invention.

[0074] Fig.12 Schematic diagram of the force transmission chain direction of other embodiments of the present invention

[0075] Description of reference numerals:

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

[0077] 20. Tubular telescopic components;

[0078] 30. telescopic driving mechanism; 31. screw rod; 32. transmission nut;

[0079] 40. Speed-changing transmission mechanism; 41. Level 3 spur teeth; 42. Central transmission shaft; 43. Level 2 second spur teeth; 44. Level 2 first spur teeth; 45. Level 1 spur teeth;

[0080] 50. Motor;

[0081] 60. planetary gear reduction mechanism; 61. sun gear; 62. cage; 63. planetary gear shaft; 64. planetary gear; 65. inner gear ring; 651. sliding ring seat; 6510. inner gear ring spline groove; 66. gasket; 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, limiting ring plate; 812, radial guide block; 814, clutch seat spline groove; 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. Braking torsion spring; 93. Second torsion spring seat; 94. Friction element;

[0085] 100. First force transmission chain;

[0086] 200, second force transmission chain;

[0087] 300, third force transmission chain;

[0088] a, first force transmission direction; b, second force transmission direction; c, third force transmission direction. DETAILED DESCRIPTION

[0089] The following is combined with Figure 1-12 The present invention is described in further detail.

[0090] Embodiment 1: A linear actuator is disclosed, referring to Figure 1-Figure 3, including an outer tube 10, a shell 13, a motor 50, a tubular telescopic component 20 and a force transmission chain; the force transmission chain includes a first force transmission chain 100, a second force transmission chain 200 and a third force transmission chain 300; the motor 50 is fixed to the shell 13 by bolts; the first force transmission chain 100 and the second force transmission chain 200 are arranged in the shell 13; the third force transmission chain 300 is arranged on the shell 13; the outer tube 10 is fixed to the shell 13; the tubular telescopic component 20 is telescopically arranged in the outer tube 10; the power of the motor 50 sequentially passes through the first force transmission chain 100, the second force transmission chain 200 and the third force transmission chain 300 to drive the tubular telescopic component 20 to perform linear motion. When the tubular telescopic component 20 extends and moves, the force transmission direction of the first force transmission chain 100 is the first force transmission direction a, the force transmission direction of the second force transmission chain 200 is the second force transmission direction b, and the force transmission direction of the third force transmission chain 300 is the third force transmission direction c.

[0091] refer to Figure 1-Figure 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 screwed to form a transmission box with a hollow interior; the outer tube 10 is fixed to the end surface of the upper shell 11 away from the lower shell 12 by screws; the support plate 15 is fixed in the lower shell 12 by screws; the positioning plate 14 is fixed in 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 side of 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 the force transmission directions of the two are arranged in parallel, and the linear actuator The overall length 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 previous method of setting the motor perpendicular to the lead screw, the first force transmission chain 100 and the third force transmission chain 300 are close to each other in a parallel posture. Generally speaking, the motor can directly output torque to the first force transmission chain 100, which makes the output shaft axial direction of the motor parallel to the first force transmission direction a, and then makes the motor parallel to the lead screw, and the overall volume of the linear actuator is reduced, which is convenient for transportation and installation in a small space.

[0092] refer to 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] refer to Figure 3 and Figure 8The planetary gear reduction mechanism 60 includes a sun gear 61, a retaining frame 62, four planetary gears 64 rotatably connected to the retaining frame 62, and an inner gear ring 65; the sun gear 61 is coaxially arranged in the inner gear ring 65; the four planetary gears 64 are located between the sun gear 61 and the inner gear ring 65; the planetary gears 64 are respectively meshed with the sun gear 61 and the inner gear ring 65; the end of the output shaft of the motor 50 is double-flat; a slot that cooperates with 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] refer to Fig. 9 The retainer 62 is cross-shaped; the four ends and the center of the retainer 62 are respectively formed with vertically penetrating rotation connection holes; the middle part of the planetary wheel 64 is axially penetrated by a planetary wheel shaft 63; both ends of the planetary wheel shaft 63 are formed with annular groove-shaped clamping grooves; one end of the planetary wheel shaft 63 passes through the rotation connection hole at the end of the retainer 62 and a clamping ring 67 is installed in its clamping groove; the end of the planetary wheel shaft 63 away from the retainer 62 is sequentially sleeved with a backing ring 66, a planetary wheel 64 and a backing ring 66 A snap ring 67 is installed in the clamping groove at the end; the end of the planetary gear shaft 63 away from the retainer 62 is rotatably connected to the upper shell 11; the sun gear 61 is integrally formed with a sun gear shaft; the end of the sun gear shaft away from the sun gear 61 is formed with a circular groove-shaped clamping groove; the sun gear shaft passes through the central rotation connection hole of the retainer 62 and a snap ring 67 is installed in the clamping groove at the end; a backing ring 66 is sleeved on the sun gear shaft and the two ends of the backing ring 66 contact the sun gear 61 and the retainer 62 respectively. Since the area of ​​the backing 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] refer to Figure 2 and Figure 3 The main body of the inner gear ring 65 is a cylinder with an opening at one end and teeth are formed on the inner cylindrical surface; the retaining frame 62, the planetary gear 64 and the sun gear 61 are located in the opening of the main body of the inner gear ring 65; the inner 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 top hole is formed on the top surface of the main body of the inner gear ring 65.

[0096] refer to Figure 2-Figure 7The 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 connecting ring 712, and the other end is formed with a coaxially arranged annular second connecting ring 713; the inner diameters of the second connecting ring 713 and the first connecting ring 712 are respectively the same as the inner diameter of the clutch support ring 711, and the outer diameters are both smaller than the clutch support ring The outer diameter of 711; the outer cylindrical surface of the first connecting ring 712 is formed with eight first splines 7121 evenly distributed around the circumference; one end of the first spline 7121 is fixed to the clutch support ring 711; the outer cylindrical surface of the second connecting ring 713 is formed with six second splines 7131 evenly distributed around the circumference; one end of the second spline 7131 is fixed to the clutch support ring 711; the end surface of the inner gear ring 65 close to the movable sleeve 71 is formed with a coaxially arranged annular sliding ring seat 651; the sliding ring seat 651 is fixed to the clutch support ring ... the one end of the first spline 7121 is fixed to the clutch support ring 711; the outer cylindrical surface of the second connecting ring 713 is formed with six second splines 7131 evenly distributed around the circumference; the one end of the second spline 7131 is fixed to the clutch support ring 711; the outer cylindrical surface of the second connecting ring 713 is formed with six second splines 7131 evenly distributed around the Six inner gear ring spline grooves 6510 respectively matched with the second spline 7131 are formed on the inner cylindrical surface of the transfer ring seat 651; the compression spring 72, the inner gear ring spline groove 6510 and the second spline 7131 correspond to each other; the second spline 7131 is slidably arranged in the inner gear ring spline groove 6510 on the corresponding side; the compression spring 72 is located in the inner gear ring spline groove 6510 on the corresponding side, and one end of the compression spring 72 abuts against the bottom surface of the inner gear ring spline groove 6510 on the corresponding side, and the other end abuts against the second spline 7131 on the corresponding side. 31; The function of the compression spring 72 is to bias the movable sleeve 71 toward the centrifugal brake 80, so that the movable sleeve 71 is not easily separated from the centrifugal brake 80, thereby ensuring the normal transmission of the motor power; in order to prevent the compression spring 72 from shifting, the bottom surface of the inner gear ring spline groove 6510 and the end surface of the second spline 7131 close to the inner gear ring spline groove 6510 are respectively formed with compression spring slots for inserting the compression spring 72, and the two ends of the compression spring 72 are respectively located in the compression spring slots on the corresponding sides, so that the compression spring 72 is not easily shifted.

[0097] The above is to realize the connection between the movable sleeve 71 and the inner gear ring 65 by spline matching, that is, when working normally, the power of the motor 50 can be transmitted to the second power transmission chain through the sun gear 61, the planetary gear 62, the inner gear ring 65, the movable sleeve 71 and the centrifugal brake 80 in sequence. Of course, the engagement mode between the inner gear ring 65 and the movable sleeve 71 can be one of ratchet matching, axial hole pin matching and non-circular shaft hole matching. When the ratchet is matched, one of the inner gear ring 65 and the movable sleeve 75 is fixed with the ratchet, and the other is rotatably connected with the ratchet. During normal operation, the ratchet and the ratchet cooperate to prevent the inner gear ring 65 from rotating forward. When released, the inner gear ring 65 can rotate in the opposite direction; when the axial hole pin is matched, one of the inner gear ring 65 and the movable sleeve 74 is formed with a hole that is non-coaxial and axially parallel to the other, and the other is formed with a pin that matches it; when the non-circular shaft hole is matched, one of the inner 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 matches it, such as a square cylindrical pin.

[0098] In this embodiment, the inner ring gear 65 is freely rotatable, and the inner ring gear 65 is the output end of the planetary gear reduction mechanism 60; in other embodiments, the inner ring gear 65 can also be fixed, and then the retaining frame 62 can be used as the output end of the planetary gear reduction mechanism 60, and then the movable sleeve 75 and the retaining frame 62 are connected with relative axial sliding; the connection method between the movable sleeve 75 and the retaining frame 62 can refer to the connection method between the movable sleeve 75 and the inner ring gear 65.

[0099] refer to Figure 2-Figure 7 The outer cylindrical surface of the middle part of the clutch support ring 711 is formed with a circular groove-shaped lever slot 7110 so that the axial sides of the lever slot 7110 are respectively formed into annular stops; the release component includes a lever 73 and an operating rod 74; the lever 73 includes an arc-shaped shift block and a vertical plate portion formed on the outer cylindrical surface of the shift block; the side wall of the upper shell 12 away from the telescopic drive mechanism 30 protrudes outward and is formed with a square groove-shaped operation limit groove 121; the operating rod 74 is axially penetrated in the operation limit groove 121 and the two ends of the operating rod 74 are transmitted out of the operation limit groove 121. The axial direction of the operating rod 74 is parallel to the axial direction of the movable sleeve 71; the shift block of the lever 73 is radially inserted in the lever slot 7110, and the vertical plate portion is screwed on the operating rod 74. In order to reduce the friction between the movable sleeve 71 and the lever 73, the movable sleeve 71 is made of self-lubricating plastic material, which ultimately reduces noise.

[0100] Of course, the lever 73 may not be translated. The center of the vertical plate portion of the lever 73 is rotatably connected to the transmission box, and then the end of the vertical plate portion of the lever 73 away from the shift block extends out of the transmission box and the operating rod 72 is connected thereto. In this way, the lever 73 is driven to rotate by the operating rod 74, and the shift block of the lever 73 abuts against and pushes the annular stop on the corresponding side, thereby driving the movable sleeve 71 to move axially along the inner gear ring 65; due to the presence of the compression spring 72, there can be only one annular stop and it is located on the side of the shift block of the lever 73 close to the inner gear ring 65.

[0101] refer to Figure 3 and Figure 5 The centrifugal brake 80 includes a rotating part, a brake housing 83 and six fan-shaped brake blocks 82; the rotating part includes a connecting shaft 84 and a clutch seat 81 that are engaged with each other; the brake housing 83 is fixed on the positioning plate 14; the clutch seat 81 is located in the brake housing 83 and the two are coaxially arranged. The clutch seat 81 of the rotating part 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 part 20 is extended, 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 force transmission chain 200 and the third force transmission chain 300, and the third force transmission chain 300 is used for deceleration and torque increase output. At this time, due to the slow rotation speed of the rotating part, the brake block 82 will not contact the brake housing 83, so that no friction braking force will be generated; when the motor 50 loses power When force is applied, due to the braking torque of the motor 50 itself, the output end of the planetary gear reduction mechanism cannot rotate in the opposite direction. At this time, the release component 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 through the third force transmission chain 300, the second force transmission chain 200, and the connecting shaft 84 in sequence, so that the release function of the linear actuator is activated. At the same time, the rotating clutch seat 81 drives the brake block 82 to move and rotate. The brake block 82 moves radially outward due to the centrifugal force and contacts the brake shell 83 to generate a centrifugal braking force to balance the load torque.

[0102] refer to Figure 6 and Figure 7The clutch seat 81 is annular; the inner cylindrical surface of the clutch seat 81 is formed with eight clutch seat spline grooves 814 respectively matched with the first spline 7121 at one end thereof near the movable sleeve 71; the connecting shaft 84 includes a stepped cylindrical connecting main seat 841; the large diameter end of the connecting main seat 841 is formed with a coaxially arranged flat columnar connecting column 842; the step of the connecting shaft 84 is formed with four circumferentially evenly distributed connecting splines 843; the inner cylindrical surface of the clutch seat 81 is formed with four connecting spline grooves 810 respectively matched with the connecting splines 843 at one end thereof away from the movable sleeve 71; the positioning plate 14 is rotatably connected with the connecting main seat 841 of the connecting shaft 84 through a bearing; the supporting plate 15 is formed with a circular hole for the connecting column 842 to pass through and rotate. 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] refer to Figure 5 and Fig.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 the gap; six radial guide blocks 812 are formed on the outer cylindrical surface of the clutch seat 81 and are evenly distributed; the radial guide blocks 812 correspond to the brake blocks 82 one by one; a radial guide groove 820 matching the radial guide block 812 is formed in the middle of the inner surface of the brake block 82 near the clutch seat 81; the radial guide groove 820 is radially sleeved on the corresponding radial guide block 812; the brake block 82 can move radially in the gap between the clutch seat 81 and the brake housing 83. Of course, the radial guide block 812 can also be set on the inner side surface of the brake block 82, and the radial guide groove 820 can be set on the outer circumferential surface of the rotating component. In other embodiments, six guide grooves can also be formed on the outer cylindrical surface of the clutch seat 81, and the brake block 82 moves radially in the guide groove. In the above structures, the rotating clutch seat 81 drives the brake block 82 to rotate together, so that the brake block 82 generates centrifugal force and moves radially outward, thereby rubbing with the brake housing 83 to generate braking force.

[0104] Six partitioning vertical plates may also be formed on the outer cylindrical surface of the clutch seat 81; the partitioning vertical plates are located between adjacent brake blocks 82. In addition, the brake block 82 may not be radially guided in the manner described above, and one end of the brake block 82 may be hinged to the outer peripheral surface of the rotating component, while the other end is in a free state. When the brake block 82 is subjected to centrifugal force, the free end of the brake block 82 may 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 coaxially arranged annular limiting ring plate 811 is formed on 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] refer to Figure 2-Figure 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 Figure 2-Figure 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 transmission mechanism 40 can select one of the gear, worm wheel and worm as the input component, which is connected to the retaining frame 62; and can select one of the gear, worm wheel and worm as the output component, which is connected to the screw 31.

[0111] Working principle of embodiment 1: 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 inner ring spline groove 6510 of the inner ring 65, so that the inner ring 65, the movable sleeve 71 and the clutch seat 81 are connected as a whole, so that the motor 50 drives the sun gear 61 to rotate, the sun gear 61 drives the four planetary gears 64 to rotate, and the four rotating planetary gears 64 drive the inner ring 65 to rotate, and the clutch seat 81, the connecting shaft 84 and the first-level spur gear 45 are driven to rotate synchronously through the movable sleeve 71, and then the second-level first spur gear 44, the second-level second spur gear 43 and the third-level spur gear 41 are used to drive the screw 31 of the telescopic drive mechanism 30 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 component 20 to extend.

[0112] When released, the operating rod 74 drives the lever 73 and the movable sleeve 71 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, the tubular telescopic component 20 is retracted due to the load, that is, the transmission nut 32 returns to its position, thereby driving the screw 31 of the telescopic drive mechanism 30 to rotate in the opposite direction, and then drives the connecting shaft 84 and the clutch seat 81 to rotate through the third-level spur teeth 41, the second-level second spur teeth 43, the second-level first spur teeth 44 and the first-level spur teeth 45 in sequence, thereby achieving release. In this way, the load torque will not be transmitted to the planetary gear reduction mechanism 60, and the components of the planetary gear reduction mechanism 60 will not participate in the work at this time, thereby reducing wear and increasing service life.

[0113] When releasing, 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 shell 83 to generate friction, thereby playing a role of reverse braking, so that the contraction speed of the tubular telescopic component 20 will not be too fast and will not form an impact. In addition, the load size 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 clutch seat 81 after transmission is also different, that is, the rotation speed of the brake block 82 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.

[0114] Embodiment 2: The difference between Embodiment 2 and Embodiment 1 is that the release component includes two shifting rods 73 and two operating rods 74, and also includes a connecting rod; the shifting blocks of the shifting rods 73 are radially inserted into the shifting rod slots 7110 at the same time, and then the operating rods 74 pass through the transmission box, one end of the operating rod 74 is fixedly connected to the vertical plate part of the shifting rod 73 on the corresponding side, and the other end is fixedly connected to the connecting rod; during operation, driving the connecting rod can realize the synchronous movement of the two operating rods 74 and the two shifting rods 73, so that the driving direction is more accurate.

[0115] In addition to the case where the release component includes a pair of levers 73 and a pair of operating rods 74, in other embodiments, the release component can have more than two levers 73 and operating rods 74, so that the movable sleeve 71 will not move in a biased direction due to the eccentric force of the movable sleeve 71 during movement as when a single fork is driven. In this way, the movable sleeve 71 and the clutch seat 81 do not need high matching accuracy to achieve precise guiding, thereby reducing processing costs.

[0116] Embodiment 3: The difference between Embodiment 3 and Embodiment 1 is: Fig.11 The linear actuator also includes a torsion spring brake 90, which 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 the end of the lead screw 31 away from the transmission nut 32, and the lead screw 31 and the first torsion spring seat 91 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 61 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 91 is non-rotatably connected to the lead screw 31; the two ends of the braking torsion spring 92 are respectively clamped with 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 the end of the second torsion spring seat 93 away from the braking torsion spring 92 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.

[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; Fig.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 invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A linear actuator, comprising: Motor; Tubular telescopic member; A force transmission chain, configured to transmit power of the motor to the tubular telescopic component to drive the tubular telescopic component to perform linear motion; It is characterized in that: the force transmission chain includes: 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; 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; A third force transmission chain drivingly connected to the second force transmission chain, comprising a screw rod and a transmission nut threadedly engaged with the screw rod, wherein the transmission nut is connected to the tubular telescopic component; The force transmission direction of the first force transmission chain intersects with the force transmission direction of the second force transmission chain, and the force transmission direction of the second force transmission chain intersects with the force transmission direction of the third force transmission chain.

2. A linear actuator according to claim 1, characterized in that: The force transmission direction of the first force transmission chain is from the input end 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 screw rod; The force transmission direction of the first force transmission chain and the force transmission direction of the third force transmission chain are arranged in parallel.

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

4. A linear actuator according to claim 1, characterized in that: The first force transmission chain also includes a clutch and a release component; A clutch, arranged between the output end of the planetary gear reduction mechanism and the input end of the centrifugal brake; 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.

5. A linear actuator according to claim 4, characterized in that: The centrifugal brake comprises: A rotating component drivingly connected between the clutch and an input end of the second force transmission chain; A brake housing, providing a braking friction surface; The brake pad disposed between the rotating member and the brake housing generates centrifugal motion due to the rotational motion of the rotating member and contacts the brake friction surface.

6. A linear actuator according to claim 5, characterized in that: One of the brake block and the rotating component is provided with a radial guide groove, and the other is provided with a radial guide block, wherein the radial guide block is inserted into the radial guide groove to guide the centrifugal movement of the brake block; Alternatively, the outer peripheral surface of the rotating component has a guide groove adapted to the brake block, the brake block is embedded in the guide groove, and the brake block and the rotating component keep synchronous rotation in the circumferential direction and can move relative to each other in the radial direction; Alternatively, one end of the brake block is pivotally connected to the rotating component, and the other end constitutes a free end capable of radially moving relative to the rotating component.

7. A linear actuator according to claim 5, characterized in that: 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.

8. A linear actuator according to claim 4, characterized in that: 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, characterized in that: 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, characterized in that: An annular stop is arranged on the clutch along its circumference, and the shifting rod has an arc-shaped shifting block, and the shifting block axially pushes against the annular stop to drive the clutch.

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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