Electric push rod
By using the axial engagement and disengagement mechanism of the fixed sleeve and the movable sleeve in the transmission device, the problem of pinching injury when the electric push rod clamps onto objects or people is solved, achieving a simple and stable anti-pinch function and reducing costs.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ZHEJIANG JIECHANG LINEAR MOTION TECH
- Filing Date
- 2025-06-30
- Publication Date
- 2026-05-15
AI Technical Summary
Existing electric actuators are prone to trapping objects or people when the tubular telescopic components retract, resulting in complex structures, high costs, and easy failure.
The transmission device includes a fixed sleeve, a movable sleeve, and an elastic element. It achieves clutch engagement through axial relative movement, preventing the tubular telescopic component from pinching objects or people when it retracts. The structure is simple and requires no control system.
It achieves anti-pinch in mechanical structure, is stable and effective in use, avoids damage to objects or people, simplifies structural design, and reduces costs.
Smart Images
Figure CN2025105814_15052026_PF_FP_ABST
Abstract
Description
An electric linear actuator Technical Field
[0001] This invention relates to the field of linear actuators, and more particularly to an electric linear actuator. Background Technology
[0002] Electric linear actuators are widely used in furniture, medical equipment, solar power generation, and other fields. Their main structure includes a drive motor, an intermediate transmission device, a lead screw, and a transmission nut. The working principle is that the drive motor starts and drives the lead screw to rotate through the intermediate transmission device. 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.
[0003] In general, if an object or a person is caught in the tubular telescopic component during the retraction of an electric linear actuator, the control device on the electric linear actuator will stop the tubular telescopic component from retracting. However, this method requires a monitoring system and a circuit control system to control the actuator and transmission system, which is complex, costly, and prone to failure. Summary of the Invention
[0004] To overcome the shortcomings of the prior art, the present invention provides an electric linear actuator, which has the advantages of simple structure and stable and effective use.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] An electric linear actuator, comprising:
[0007] Electric motor;
[0008] Tubular telescopic components;
[0009] The transmission device transmits the power of the motor to the tubular telescopic component to drive the tubular telescopic component to perform linear motion;
[0010] The transmission device includes a lead screw and a transmission nut threaded onto the lead screw, and the transmission nut is connected to the tubular telescopic component;
[0011] The transmission device further includes a clutch; the clutch includes a fixed sleeve, a movable sleeve, and an elastic element; the fixed sleeve is driven to rotate by the output power of the motor; the movable sleeve is connected to the lead screw; when the fixed sleeve and the movable sleeve are engaged, they remain circumferentially fixed and can move axially relative to each other, allowing the lead screw to move in the extension direction of the tubular telescopic component when subjected to axial tension, thereby causing the fixed sleeve and the movable sleeve to separate axially; the elastic element acts on the lead screw to maintain its force state in the retraction direction of the tubular telescopic component.
[0012] By adopting the above technical solution, during normal operation, the motor's output power drives the fixed sleeve to rotate. The movable sleeve, which meshes with the fixed sleeve, drives the lead screw to rotate, which in turn drives the tubular telescopic component to perform a linear telescopic movement through the transmission nut. However, when the tubular telescopic component retracts, if it clamps an object or a person, the tubular telescopic component will be subjected to a reverse pulling force. This causes the transmission nut, lead screw, and movable sleeve connected to the tubular telescopic component to move outward together. At this time, the movable sleeve and the fixed sleeve separate, the motor's output power cannot be transmitted to the lead screw, the lead screw cannot continue to rotate, and the tubular telescopic component cannot retract. Thus, the object or person will not be pulled back and injured. No control system is required during this process, achieving anti-pinch in the mechanical structure. The structure is simple and the use is stable and effective.
[0013] Optionally, the fixed sleeve has a first engaging block parallel to its axial direction; the movable sleeve has a second engaging block parallel to its axial direction; the first engaging block and the second engaging block cooperate with each other to achieve the engagement of the fixed sleeve and the movable sleeve.
[0014] By adopting the above technical solution, the first and second connecting blocks are joined by axially parallel blocks, and the connection and separation of the fixed sleeve and the movable sleeve are achieved when they move relative to each other axially. This structure is simple to connect and has high connection and separation efficiency.
[0015] Optionally, at least one of the first and second joining blocks has a joining guide surface to guide the first and second joining blocks to join.
[0016] By adopting the above technical solution, the presence of the engagement guide surface makes the connection between the engagement blocks on the fixed sleeve and the movable sleeve smoother during engagement.
[0017] Optionally, the fixed sleeve and the movable sleeve are engaged by a ratchet mechanism.
[0018] By adopting the above technical solution, the fixed sleeve and the movable sleeve are engaged by a ratchet mechanism, which makes the clutch more smooth when disengaging and engaging, and prevents situations where disengagement and engagement are impossible.
[0019] Optionally, the ratchet teeth of the fixed sleeve and the movable sleeve are respectively the first engaging block and the second engaging block; the inclined surface of the ratchet teeth is the engaging guide surface; the angle between the engaging guide surface and the axial direction of the fixed sleeve and the movable sleeve is 20-65 degrees.
[0020] By adopting the above technical solution, the inclined surface of the ratchet is at an angle of 20-65 degrees to the axis of the fixed sleeve and the movable sleeve, so that the ratchet is less likely to slip when engaged, which is conducive to the normal transmission of torque.
[0021] Optionally, the fixed sleeve and the movable sleeve are joined by a pointed spline.
[0022] By adopting the above technical solution, the fixed sleeve and the movable sleeve are engaged by a pointed spline method; this makes the clutch engagement and disengagement smoother, preventing situations where engagement or disengagement is impossible. Furthermore, the pointed spline method can withstand greater torque than the ratchet method, and it is also simpler to manufacture than the ratchet method.
[0023] Optionally, the key teeth of the fixed sleeve and the movable sleeve are the first engaging block and the second engaging block, respectively; one end of the key tooth is formed with a sharp corner and the inclined surface of the sharp corner is the engaging guide surface.
[0024] By adopting the above technical solution, when the movable sleeve approaches the fixed sleeve, the sharp corners of the key teeth can guide the key teeth on the movable sleeve and the fixed sleeve to engage quickly, resulting in a smoother connection.
[0025] Optionally, it also includes a reduction transmission mechanism with a planetary gear assembly or a worm gear assembly, wherein the sun gear or worm is the input component and the planetary gear carrier or worm gear is the output component; the output component is connected to the fixed sleeve in a transmission connection.
[0026] By adopting the above technical solutions, the reduction transmission mechanism of the planetary gear assembly or worm gear assembly can achieve speed reduction and torque increase to withstand greater loads.
[0027] Optionally, the lead screw passes through the fixed sleeve; the fixed sleeve and the output component are circumferentially fixed and axially movable; the tail of the electric push rod is provided with a thrust bearing, which abuts against the tail pull of the electric push rod; the axial thrust borne by the lead screw passes through the output component and reaches the thrust bearing through the clutch.
[0028] By adopting the above technical solution, since the fixed sleeve and the output component are circumferentially fixed and axially movable, the axial thrust borne by the electric push rod will not be transmitted to the output component through the lead screw, but will directly reach the thrust bearing through the clutch. The thrust bearing replaces the gearbox housing in bearing the force, making the gearbox housing less prone to deformation and avoiding affecting the connection of the components inside the gearbox.
[0029] Optionally, a stop ring is provided on the fixed sleeve; a stop member is connected to the end of the lead screw near the thrust bearing; the stop ring is located at the end of the fixed sleeve near the stop member; the elastic member provides a thrust that moves the stop member and the fixed sleeve away from each other.
[0030] By adopting the above technical solution, the elastic element is set at the end of the lead screw, which makes assembly convenient; the function of the elastic element ensures that the stop ring always abuts against the output component, that is, the fixed sleeve and the output component are always in a normal transmission connection state, which is conducive to torque transmission; in addition, when the lead screw is subjected to axial tension, the elastic element increases the thrust on the fixed sleeve, making it more difficult for the fixed sleeve to detach from the output component. Attached Figure Description
[0031] Figure 1 is a structural schematic diagram of Embodiment 1 of the present invention.
[0032] Figure 2 is a partial cross-sectional structural diagram of Embodiment 1 of the present invention.
[0033] Figure 3 is a schematic diagram of the explosion structure of Embodiment 1 of the present invention.
[0034] Figure 4 is a schematic diagram of the explosion structure of Embodiment 1 of the present invention.
[0035] Figure 5 is a schematic diagram of the separation of the fixed sleeve and the movable sleeve in Embodiment 1 of the present invention.
[0036] Figure 6 is a schematic diagram of the explosion structure of Embodiment 2 of the present invention.
[0037] Figure 7 is a schematic diagram of the separation of the fixed sleeve and the movable sleeve in Embodiment 2 of the present invention.
[0038] Explanation of reference numerals in the attached drawings: 10. Gearbox; 11. Motor cover; 12. Tail pull; 13. Outer tube; 20. Motor; 30. Reduction transmission mechanism; 31. Worm; 32. Worm wheel; 40. Clutch; 41. Movable sleeve; 42. Fixed sleeve; 421. Racket; 422. Inclined surface; 423. Key; 424. Inclined surface; 425. Stop ring; 43. Elastic element; 50. Torsion spring brake; 51. Torsion spring seat; 52. Brake torsion spring; 60. Thrust bearing; 70. Lead screw; 80. Transmission nut; 90. Tubular telescopic component. Detailed Implementation
[0039] The present invention will be further described in detail below with reference to Figures 1-7.
[0040] Example 1: An electric actuator is disclosed. Referring to Figures 1 and 2, it includes a housing, a motor 20, a transmission device, and a tubular telescopic component 90. The housing includes a gearbox 10, a motor housing 11, and an outer tube 13. The motor housing 11 and the outer tube 13 are respectively connected to the gearbox 10. A tail pull 12 is fixed to the end of the gearbox 10 away from the outer tube 13. The motor 20 is located inside the motor housing 11. The transmission device includes a reduction transmission mechanism 30, a clutch 40, a lead screw 70, and a transmission nut 80 threadedly engaged with the lead screw 70. The output power of the motor 20 is transmitted to the lead screw 70 through the reduction transmission mechanism 30 and the clutch 40. The reduction transmission mechanism 30 and the clutch 40 are disposed inside the gearbox 10. The tubular telescopic component 90 is threadedly connected to the transmission nut 80. The transmission nut 80 is axially sliding inside the outer tube 13. The tubular telescopic component 90 is axially telescopically disposed inside the outer tube 13.
[0041] Referring to Figure 3, the reduction transmission mechanism 30 includes a worm 31 and a worm wheel 32 that mesh with each other; the worm 31 is coaxially and fixedly connected to the output shaft of the motor 20; the worm wheel 32 is connected to the clutch 40; in this case, the worm 31 is the input component of the reduction transmission mechanism 30, and the worm wheel 32 is the output component of the reduction transmission mechanism 30; in other embodiments, the reduction transmission mechanism 30 includes a planetary gear assembly; the planetary gear assembly refers to existing structures; the sun gear of the planetary gear assembly is coaxially and fixedly connected to the output shaft of the motor 20, serving as the input component; the planet carrier of the planetary gear assembly serves as the output component and is connected to the clutch 40; in addition, the reduction transmission mechanism 30 includes a gear reduction assembly; the driving gear of the gear reduction assembly is coaxially and fixedly connected to the output shaft of the motor 20, serving as the input component; the driven gear of the gear reduction assembly serves as the output component and is connected to the clutch 40.
[0042] Referring to Figures 2 and 3, the clutch 40 includes a fixed sleeve 42, a movable sleeve 41, and an elastic element 43. The fixed sleeve 42 is coaxially connected to the worm gear 32 via a spline, so that the worm gear 32 and the fixed sleeve 42 are axially fixed and parallel to each other. The rotating worm gear 32 can drive the fixed sleeve 42 to rotate, but the axial force on the fixed sleeve 42 will not be transmitted to the worm gear 32. The movable sleeve 41 is coaxially sleeved on the lead screw 70 and the two are interference-fitted. In other embodiments, the fixed sleeve 42 and the worm gear 32 can also be fitted by an axial hole pin. In this case, one of the fixed sleeve 42 and the worm gear 32 is formed with a hole that is not coaxial with both but axially parallel, and the other is formed with a pin that fits with it.
[0043] Referring to Figures 2-4, the end of the lead screw 70 near the tail pull 12 coaxially passes through the fixed sleeve 42, and this end is connected to a retaining element; the retaining element includes a retaining ring 72; the retaining ring 72 is fixed to the end of the lead screw 70 by a limiting screw 71; the elastic element 43 can be any one of a compression spring, a disc spring, and a rubber spring; the end of the fixed sleeve 42 near the tail pull 12 is formed with a circular cylindrical groove for the elastic element mounting; the compression spring is sleeved on the lead screw 70, with one end abutting against the retaining ring 72 and the other end abutting against the inner wall of the elastic element mounting groove, so that the compression spring provides a thrust that pushes the retaining ring 72 and the fixed sleeve 42 away from each other. In order to ensure the connection stability between the fixed sleeve 42 and the worm gear 32, a stop ring 425 is formed on the fixed sleeve 42; the stop ring 425 abuts against the end face of the worm gear 32 near the tail pull 12 under the action of the compression spring, so that the fixed sleeve 42 is not easy to detach from the worm gear 32.
[0044] Referring to Figure 5, the movable sleeve 41 and the fixed sleeve 42 are connected at their close ends by a ratchet mechanism. Specifically, both the movable sleeve 41 and the fixed sleeve 42 have ratchet teeth 421 formed at their respective ends. The angle between the inclined surface 422 of the ratchet teeth 421 and the axial direction of the movable sleeve 41 and the fixed sleeve 42 is 20-65 degrees. Under the action of the elastic element 43, the movable sleeve 41 and the fixed sleeve 42 are engaged together through the ratchet teeth 421 to transmit torque. Because the angle between the inclined surface 422 of the ratchet teeth 421 and the axial direction of the movable sleeve 41 and the fixed sleeve 42 is 20-65 degrees, slippage is less likely during torque transmission, achieving stable torque transmission. As the movable sleeve 41 and the fixed sleeve 42 approach each other, the inclined surface 422 of the ratchet teeth 421 guides the ratchet teeth 421 of the movable sleeve 41 and the fixed sleeve 42 to engage quickly, resulting in smoother engagement.
[0045] Referring to Figures 2 and 3, to improve the rotational stability of the fixed sleeve 42, both ends of the fixed sleeve 42 are rotatably connected to the gearbox 10 via bearings. Simultaneously, to prevent stress on the gearbox 10 housing, a thrust bearing 60 is installed at the tail pull 12, and the fixed sleeve 42 abuts against the thrust bearing 60. Thus, when the lead screw 70 bears axial thrust, the axial thrust is directly transmitted to the thrust bearing 60 through the guides of the movable sleeve 41 and the fixed sleeve 42. This prevents stress on the gearbox 10 housing, making it less prone to deformation and thus not affecting the connection of components within the gearbox 10.
[0046] Working principle of Example 1: When the tubular telescopic component 90 extends, the motor 20 drives the fixed sleeve 42 to rotate after deceleration and torque increase through the worm 31 and worm wheel 32. The fixed sleeve 42 drives the lead screw 70 to rotate through the movable sleeve 41 connected to it. The lead screw 70 drives the transmission nut 80 screwed to it to slide along the axial direction of the outer tube 13. The transmission nut 80 drives the tubular telescopic component 90 to extend. When the tubular telescopic component 90 retracts, the motor 20 reverses and drives the tubular telescopic component 90 to retract through the above working principle.
[0047] During the retraction of the tubular telescopic component 90, when it clamps an object or a person, the tubular telescopic component 90 will be subjected to axial tension. This causes the transmission nut 80, movable sleeve 41, lead screw 70, and movable sleeve 41 to move outward together, causing the movable sleeve 41 to separate from the fixed sleeve 42. As a result, the output power of the motor 20 cannot be transmitted to the lead screw 70, and the lead screw 70 stops rotating, thus preventing the clamped object or person from being pulled back and causing damage. When the object or person is removed, due to the action of the elastic element 43, the lead screw 70 moves axially inward, causing the movable sleeve 41 to re-engage with the fixed sleeve 42. The output power of the motor 20 drives the lead screw 70 to rotate, thereby causing the transmission nut 80 and the tubular telescopic component 90 to retract.
[0048] Example 2: The difference between Example 2 and Example 1 is as follows: Referring to Figures 5-7, the movable sleeve 41 and the fixed sleeve 42 are joined by a pointed spline method. That is, the ends of the movable sleeve 41 and the fixed sleeve 42 that are close to each other are formed with key teeth 423, and the joint ends of the key teeth 423 are formed with pointed corners. When the movable sleeve 41 and the fixed sleeve 42 are joined, the torque is transmitted through the mutually abutting key teeth 423, so the torque transmission is smooth and can withstand a large torque. During the joining process of the movable sleeve 41 and the fixed sleeve 42, the inclined surface 424 of the pointed corner guides the key teeth 423 to engage quickly, making the engagement smoother. Of course, it is not necessary for all key teeth 423 to have pointed corners; pointed corners can also be machined on the key teeth 423 of the movable sleeve 41 or on the key teeth 423 of the movable sleeve 41.
[0049] In Embodiment 1 and Embodiment 2, ratchet 421 and key 423 serve as engagement blocks parallel to the axial direction of movable sleeve 41 and fixed sleeve 42 to connect movable sleeve 41 and fixed sleeve 42. The inclined surface 422 of ratchet 421 and the inclined surface 424 of the tip of key 423 serve as engagement guide surfaces to guide engagement. In other embodiments, the engagement blocks on movable sleeve 41 and fixed sleeve 42 can be different. For example, fixed sleeve 42 uses an isosceles triangular block as the first engagement block, and movable sleeve 41 uses a pointed key as the second engagement block. During engagement, the tip of the first engagement block is inserted between an adjacent pair of pointed key teeth, and the inclined surface of the tip of the first engagement block abuts against the inclined surface of the tip of the second engagement block.
[0050] Example 3: The difference between Example 3 and Example 1 is that a torsion spring brake 50 is provided between the fixed sleeve 42 and the tail pull 12. The torsion spring brake 50 includes a torsion spring seat 51 and a braking torsion spring 52. The end of the fixed sleeve 42 near the tail pull 12 is double-flat. A slot is formed on the torsion spring seat 51 to mate with the end of the fixed sleeve 42. Both the torsion spring seat 51 and the tail pull 12 have connecting slots formed to mate with the end of the braking torsion spring 52. The braking torsion spring 52 is sleeved on the torsion spring seat 51 and its two ends are respectively inserted into the connecting slots of the torsion spring seat 51 and the tail pull 12. When the tubular telescopic component 90 extends, the torsion spring seat 41 rotates clockwise with the torsion spring seat 51, causing the braking torsion spring 52 to release. When the tubular telescopic component 90 retracts, the torsion spring seat 41 rotates counterclockwise with the torsion spring seat 51, causing the braking torsion spring 52 to tighten, so as to balance part of the load torque and reduce the force on the reduction transmission mechanism 30.
[0051] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.
Claims
1. An electric linear actuator, comprising: Electric motor; Tubular telescopic components; The transmission device transmits the power of the motor to the tubular telescopic component to drive the tubular telescopic component to perform linear motion; The transmission device includes a lead screw and a transmission nut threaded onto the lead screw, and the transmission nut is connected to the tubular telescopic component; The transmission device is characterized by the following features: it further includes a clutch; the clutch includes a fixed sleeve, a movable sleeve, and an elastic element; the fixed sleeve is driven to rotate by the output power of the motor; the movable sleeve is connected to the lead screw; when the fixed sleeve and the movable sleeve are engaged, they remain circumferentially fixed and can move axially relative to each other, allowing the lead screw to move in the extension direction of the tubular telescopic component when subjected to axial tension, thereby causing the fixed sleeve and the movable sleeve to separate axially; the elastic element acts on the lead screw to maintain its force state in the retraction direction of the tubular telescopic component.
2. The electric linear actuator according to claim 1, characterized in that: The fixed sleeve has a first engaging block parallel to its axial direction; the movable sleeve has a second engaging block parallel to its axial direction; the first engaging block and the second engaging block cooperate with each other to achieve the engagement of the fixed sleeve and the movable sleeve.
3. An electric linear actuator according to claim 2, characterized in that: At least one of the first and second joint blocks has a joint guide surface to guide the first and second joint blocks to join together.
4. An electric linear actuator according to claim 3, characterized in that: The fixed sleeve and the movable sleeve are engaged by a ratchet mechanism.
5. An electric linear actuator according to claim 4, characterized in that: The ratchet teeth of the fixed sleeve and the movable sleeve are respectively the first engaging block and the second engaging block; the inclined surface of the ratchet teeth is the engaging guide surface; the angle between the engaging guide surface and the axial direction of the fixed sleeve and the movable sleeve is 20-65 degrees.
6. An electric linear actuator according to claim 3, characterized in that: The fixed sleeve and the movable sleeve are joined by a pointed spline.
7. An electric linear actuator according to claim 6, characterized in that: The key teeth of the fixed sleeve and the movable sleeve are the first joint block and the second joint block, respectively; one end of the key tooth is formed with a sharp corner and the inclined surface of the sharp corner is the joint guide surface.
8. An electric linear actuator according to claim 1, characterized in that: The transmission device further includes a reduction transmission mechanism with a planetary gear assembly or a worm gear assembly, wherein the sun gear or worm is the input component and the planetary gear carrier or worm gear is the output component; the output component is connected to the fixed sleeve in a transmission connection.
9. An electric linear actuator according to claim 8, characterized in that: The lead screw passes through the fixed sleeve; the fixed sleeve and the output component are circumferentially fixed and axially movable; the tail of the electric push rod is provided with a thrust bearing, which abuts against the tail pull of the electric push rod; the axial thrust borne by the lead screw passes through the output component and reaches the thrust bearing through the clutch.
10. An electric linear actuator according to claim 9, characterized in that: A stop ring is provided on the fixed sleeve; a stop member is connected to the end of the lead screw near the thrust bearing; the stop ring is located at the end of the fixed sleeve near the stop member; the elastic member provides a thrust that moves the stop member and the fixed sleeve away from each other.