Electric push rod

Abstract

The invention discloses an electric push rod. The electric push rod comprises a motor; a tubular telescopic member; the transmission device transmits power of the motor to the tubular telescopic component so as to drive the tubular telescopic component to do linear motion; the transmission device comprises a lead screw and a transmission nut in threaded fit with the lead screw, and the transmission nut is connected with the tubular telescopic component; the transmission device further comprises a clutch. The clutch comprises a fixed sleeve, a movable sleeve and an elastic piece; the fixed sleeve is driven by output power of the motor to rotate; the movable sleeve is connected to the screw rod; when the fixed sleeve and the movable sleeve are jointed, the fixed sleeve and the movable sleeve are kept relatively fixed in the circumferential direction and can move relatively in the axial direction, and the lead screw is allowed to move in the extending direction of the tubular telescopic component when being subjected to axial tension so that the fixed sleeve and the movable sleeve can be separated in the axial direction. The elastic piece acts on the lead screw to keep the stress state of the lead screw in the retraction direction of the tubular telescopic component. No control system needs to be added, clamping prevention is achieved on a mechanical structure, the structure is simple, and use is stable and effective.

Description

Technical Field

[0001] The invention relates to the field of push rods, in particular to an electric push rod. Background Art

[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 to drive the lead screw to rotate through the intermediate transmission device, 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.

[0003] Generally, when an electric push rod is retracting a tubular telescopic part, if it catches an object or a human body, the control device on the electric push rod will stop the retraction of the tubular telescopic part. However, this method requires the use of a monitoring system and a circuit control system to control the actuator and the transmission system, which has a complex structure, high cost, and is prone to failure. Summary of the invention

[0004] In order to overcome the deficiencies in the prior art, the present invention provides an electric push rod, which has the advantages of simple structure and stable and effective use.

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

[0006] An electric push rod, comprising:

[0007] Motor;

[0008] Tubular telescopic member;

[0009] A transmission device, which 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 comprises a screw rod and a transmission nut threadedly engaged with the screw rod, and the transmission nut is connected to the tubular telescopic component;

[0011] The transmission device also includes a clutch; the clutch includes a fixed sleeve, a movable sleeve and an elastic member; the fixed sleeve is driven to rotate by the output power of the motor; the movable sleeve is connected to the screw rod; the fixed sleeve and the movable sleeve remain relatively fixed in the circumferential direction when engaged and can move relative to each other axially, allowing the screw rod 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 member acts on the screw rod 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 output power of the motor drives the fixed sleeve to rotate, and the movable sleeve engaged with the fixed sleeve drives the screw rod to rotate, and then drives the tubular telescopic component to perform telescopic linear motion through the transmission nut; however, when the tubular telescopic component retracts, if an object or a human body is clamped, the tubular telescopic component will be subjected to a reverse pulling force, so that the transmission nut, the screw rod and the movable sleeve connected to the tubular telescopic component move outward together, and the movable sleeve and the fixed sleeve are separated at this time, and the output power of the motor cannot be transmitted to the screw rod, the screw rod cannot continue to rotate, and the tubular telescopic component cannot retract, so that the object or the human body will not be driven to retract together and be damaged. In this process, there is no need to add a control system, and anti-pinching is achieved 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 realize the engagement of the fixed sleeve and the movable sleeve.

[0014] By adopting the above technical solution, the engagement is achieved through the axially parallel first engagement block and the second engagement block, and the connection and separation of the fixed sleeve and the movable sleeve are achieved when the fixed sleeve and the movable sleeve move axially relative to each other. This has a simple structure and high connection and separation efficiency.

[0015] Optionally, at least one of the first engaging block and the second engaging block has an engaging guide surface to guide the first engaging block and the second engaging block to achieve engagement.

[0016] By adopting the above technical solution, the existence of the engagement guide surface makes the engagement blocks on the fixed sleeve and the movable sleeve connected more smoothly during engagement.

[0017] Optionally, the fixed sleeve and the movable sleeve are engaged with each other by means of a ratchet.

[0018] By adopting the above technical solution, the fixed sleeve and the movable sleeve are engaged by ratchet, which can make the clutch smoother when disengaging and engaging, and prevent the situation where it cannot be disengaged and engaged.

[0019] Optionally, the ratchet teeth of the fixed sleeve and the movable sleeve are the first engagement block and the second engagement block respectively; the inclined surface of the ratchet teeth is the engagement guide surface; and the angle between the engagement 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 20-65 degrees to the axial direction of the fixed sleeve and the movable sleeve, so that the ratchet is not easy to slip when engaged, which is conducive to the normal transmission of torque.

[0021] Optionally, the fixed sleeve and the movable sleeve are engaged with each other by means of a pointed spline.

[0022] By adopting the above technical solution, the fixed sleeve and the movable sleeve are engaged by the sharp angle spline method; the clutch can be made smoother when disengaging and engaging, and the situation of being unable to disengage and engage can be prevented; at the same time, the sharp angle spline method can withstand greater torque than the ratchet method, and the sharp angle spline method is simpler in manufacturing and processing than the ratchet method.

[0023] Optionally, the key teeth of the fixed sleeve and the movable sleeve are respectively the first engaging block and the second engaging block; 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 quickly engage, making the connection smoother.

[0025] Optionally, it also includes a reduction transmission mechanism with a planetary gear assembly or a worm gear assembly, the sun gear or the worm gear is the input component, and the planetary gear carrier or the worm gear is the output component; the output component is drivingly connected to the fixed sleeve.

[0026] By adopting the above technical solution, the reduction transmission mechanism of the planetary gear assembly or the worm gear assembly can achieve speed reduction and torque increase to withstand a larger load.

[0027] Optionally, the screw rod passes through the fixed sleeve; the fixed sleeve and the output component are relatively fixed in the circumferential direction and move relatively in the axial direction; a thrust bearing is provided at the tail of the electric push rod to counteract the tail pull of the electric push rod; the axial thrust borne by the screw rod is guided by the clutch through the output component directly to the thrust bearing.

[0028] By adopting the above technical solution, since the fixed sleeve and the output component are relatively fixed in the circumferential direction and move relatively in the axial direction, the axial thrust borne by the electric push rod will not be transmitted to the output component through the screw rod, but will directly reach the thrust bearing through the clutch. The thrust bearing replaces the gearbox housing to bear the force, and the gearbox housing is not easily deformed, thereby avoiding affecting the connection of components in the gearbox.

[0029] Optionally, a stop ring is provided on the fixed sleeve; an abutment member is connected to one end of the screw rod close to the thrust bearing; the stop ring is located at one end of the fixed sleeve close to the abutment member; and the elastic member provides a thrust to move the abutment member and the fixed sleeve away from each other.

[0030] By adopting the above technical solution, the elastic member is arranged at the end of the screw rod, which makes assembly convenient; the elastic member makes the stop ring always abut against the output component, that is, the fixed sleeve and the output component are always in a normal transmission connection state, which is beneficial to the transmission of torque; in addition, when the screw rod is subjected to axial tension, the elastic member increases the thrust on the fixed sleeve, making it more difficult for the fixed sleeve to separate from the output component. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of embodiment 1 of the present invention.

[0032] Figure 2 It is a schematic structural diagram of a partial cross section of the first embodiment of the present invention.

[0033] Figure 3 It is a schematic diagram of the explosion structure of the first embodiment of the present invention.

[0034] Figure 4 It is a schematic diagram of the explosion structure of the first embodiment of the present invention.

[0035] Figure 5 It is a schematic structural diagram of the fixed sleeve and the movable sleeve separated in the first embodiment of the present invention.

[0036] Figure 6 It is a schematic diagram of the explosion structure of the second embodiment of the present invention.

[0037] Figure 7 It is a schematic structural diagram of the fixed sleeve and the movable sleeve separated in the second embodiment of the present invention.

[0038] Description of reference numerals:

[0039] 10. Gearbox; 11. Motor shield; 12. Tail pull; 13. Outer tube;

[0040] 20. Motor;

[0041] 30. reduction transmission mechanism; 31. worm; 32. worm wheel;

[0042] 40. Clutch; 41. Movable sleeve; 42. Fixed sleeve; 421. Ratchet; 422. Inclined surface; 423. Key teeth; 424. Inclined surface; 425. Stop ring; 43. Elastic member;

[0043] 50. torsion spring brake; 51. torsion spring seat; 52. brake torsion spring;

[0044] 60. Thrust bearing;

[0045] 70. Screw rod;

[0046] 80. Transmission nut;

[0047] 90. Tubular telescopic component. DETAILED DESCRIPTION

[0048] The following joints are attached Figure 1-7 The present invention is described in further detail.

[0049] Embodiment 1: Disclose an electric push rod, referring to Figure 1 and Figure 2 , including a shell, a motor 20, a transmission device and a tubular telescopic component 90; the shell includes a gearbox 10, a motor shield 11 and an outer tube 13; the motor shield 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 in the motor shield 11; the transmission device includes a reduction transmission mechanism 30, a clutch 40, a screw rod 70 and a transmission nut 80 threadedly matched with the screw rod 70; the output power of the motor 20 is transmitted to the screw rod 70 through the reduction transmission mechanism 30 and the clutch 40; the reduction transmission mechanism 30 and the clutch 40 are arranged in the gearbox 10; the tubular telescopic component 90 is threadedly connected with the transmission nut 80; the transmission nut 80 is axially slidably arranged in the outer tube 13; the tubular telescopic component 90 is axially telescopically arranged in the outer tube 13.

[0050] refer 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 fixedly connected to the output shaft of the motor 20; the worm wheel 32 is connected to the clutch 40; at this time, 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 the existing structure; the sun gear of the planetary gear assembly is coaxially fixedly connected to the output shaft of the motor 20, which is the input component; the planetary wheel carrier of the planetary gear assembly is connected to the clutch 40 as an output component; in addition, the reduction transmission mechanism 30 includes a gear reduction assembly; the driving gear of the gear reduction assembly is coaxially fixedly connected to the output shaft of the motor 20, which is the input component; the driven gear of the gear reduction assembly is connected to the clutch 40 as an output component.

[0051] refer to Figure 2 and Figure 3The clutch 40 includes a fixed sleeve 42, a movable sleeve 41 and an elastic member 43; the fixed sleeve 42 is coaxially connected to the worm wheel 32 by a spline, so that the worm wheel 32 and the fixed sleeve 42 are relatively axially fixed and axially relatively parallel, and the rotating worm wheel 32 can drive the fixed sleeve 42 to rotate, but the axial force exerted on the fixed sleeve 42 will not be transmitted to the worm wheel 32; the movable sleeve 41 is coaxially sleeved on the screw rod 70 and the two are interference fit; in other embodiments, the fixed sleeve 42 and the worm wheel 32 can also be matched with an axial hole pin, at this time, one of the fixed sleeve 42 and the worm wheel 32 is formed with a hole that is not coaxial with the two but axially parallel to the two, and the other is formed with a pin that matches therewith.

[0052] refer to Figure 2-Figure 4 , one end of the screw rod 70 near the tail pull 12 coaxially passes through the fixed sleeve 42 and this end is connected with a support member; the support member includes a retaining ring 72; the retaining ring 72 fixes the end of the screw rod 70 through a limit screw 71; the elastic member 43 can be any one of a compression spring, a disc spring and a rubber spring; one end of the fixed sleeve 42 near the tail pull 12 is formed with a circular column groove-shaped elastic member installation groove; the compression spring is sleeved on the screw rod 70 and one end abuts against the retaining ring 72 and the other end abuts against the inner side wall of the elastic member installation groove, so that the compression spring provides a thrust for the retaining ring 72 and the fixed sleeve 42 to move away from each other. In order to ensure the connection stability between the fixed sleeve 42 and the worm wheel 32, a stop ring 425 is formed on the fixed sleeve 42; the stop ring 425 abuts against the end face of the worm wheel 32 near the tail pull 12 under the action of the compression spring, so that the fixed sleeve 42 is not easy to separate from the worm wheel 32.

[0053] refer to Figure 5 The ends of the movable sleeve 41 and the fixed sleeve 42 that are close to each other are connected by a ratchet, that is, the movable sleeve 41 and the fixed sleeve 42 are both formed with ratchet teeth 421 at one end, and 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 member 43, the movable sleeve 41 and the fixed sleeve 42 are connected as a whole through the ratchet teeth 421 to transmit torque, and since 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, the two are not easy to slip during the torque transmission process, thereby realizing stable torque transmission; in the process of the movable sleeve 41 and the fixed sleeve 42 approaching 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 quickly engage, and the engagement is smoother.

[0054] refer to Figure 2 and Figure 3In order to improve the rotation stability of the fixed sleeve 42, the two axial ends of the fixed sleeve 42 are respectively connected to the gearbox 10 through bearings; at the same time, in order to prevent the housing of the gearbox 10 from being stressed, a thrust bearing 60 is installed on the tail pull 12, and the fixed sleeve 42 abuts against the thrust bearing 60. In this way, when the screw rod 70 is subjected to axial thrust, the axial thrust is directly transmitted to the thrust bearing 60 through the guidance of the movable sleeve 41 and the fixed sleeve 42, so that the housing of the gearbox 10 is not subjected to stress and is not easily deformed, thereby not affecting the connection of components in the gearbox 10.

[0055] Working principle of embodiment 1: when the tubular telescopic component 90 is extended, the motor 20 drives the fixed sleeve 42 to rotate after decelerating and increasing the torque through the worm 31 and the worm wheel 32, and the fixed sleeve 42 drives the screw rod 70 to rotate through the movable sleeve 41 engaged therewith, and the screw rod 70 drives the transmission nut 80 threaded therewith to slide axially along the outer tube 13, and the transmission nut 80 drives the tubular telescopic component 90 to extend; when the tubular telescopic component 90 is retracted, the motor 20 reverses and drives the tubular telescopic component 90 to retract through the above working principle.

[0056] During the retraction process of the tubular telescopic component 90, when an object or a human body is clamped, the tubular telescopic component 90 will be subjected to axial tension, so that the transmission nut 80, the movable sleeve 41, the screw rod 70 and the movable sleeve 41 will move outward together, so that the movable sleeve 41 is separated from the fixed sleeve 42, so that the output power of the motor 20 cannot be transmitted to the screw rod 70, and the screw rod 70 stops rotating, so as not to pull the clamped object or human body to retract together and cause damage; when the object or human body is taken out, due to the action of the elastic member 43, the screw rod 70 moves axially inward so that the movable sleeve 41 re-engages with the fixed sleeve 42, and the output power of the motor 20 drives the screw rod 70 to rotate, thereby driving the transmission nut 80 and the tubular telescopic component 90 to retract.

[0057] Embodiment 2: The difference between Embodiment 2 and Embodiment 1 is: Figure 5-Figure 7 The movable sleeve 41 and the fixed sleeve 42 are connected by a sharp angle spline, that is, the end of the movable sleeve 41 and the fixed sleeve 42 that is close to each other is formed with a key tooth 423, and the engagement end of the key tooth 423 is formed with a sharp angle; when the movable sleeve 41 and the fixed sleeve 42 are connected, the torque is transmitted through the key teeth 423 that abut against each other, so that the torque transmission is smooth and can withstand a large torque; in the process of connecting the movable sleeve 41 and the fixed sleeve 42, the inclined surface 424 with a sharp angle guides the key teeth 423 to connect quickly, and the connection is smoother. Of course, it is not necessary for all the key teeth 423 to have sharp angles, and sharp angles can also be processed on the key teeth 423 of the movable sleeve 41 or on the key teeth 423 of the movable sleeve 41.

[0058] In the first and second embodiments, the ratchet tooth 421 and the key tooth 423 are used as engaging blocks parallel to the axial direction of the movable sleeve 41 and the fixed sleeve 42 to realize the connection between the movable sleeve 41 and the fixed sleeve 42, and the inclined surface 422 of the ratchet tooth 421 and the inclined surface 424 of the sharp angle of the key tooth 423 are used as engaging guide surfaces to guide the engaging; in other embodiments, the engaging blocks on the movable sleeve 41 and the fixed sleeve 42 may be different, for example, the fixed sleeve 42 has an isosceles triangle block as the first engaging block, and the movable sleeve 41 has a sharp-angle key tooth as the second engaging block. When engaging, the sharp corner of the first engaging block is inserted between a pair of adjacent sharp-angle key teeth and the inclined surface of the sharp corner of the first engaging block abuts against the inclined surface of the sharp corner of the second engaging block.

[0059] Embodiment 3: Embodiment 3 is different from Embodiment 1 in that: a torsion spring brake 50 is provided between the fixed sleeve 42 and the tail pull 12, and the torsion spring brake 50 includes a torsion spring seat 51 and a brake 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 match the end of the fixed sleeve 42; a connecting slot is formed on the torsion spring seat 51 and the tail pull 12 to match the end of the brake torsion spring 52; the brake 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 is extended, the torsion spring seat 41 rotates forward with the torsion spring seat 51 to release the brake torsion spring 52; when the tubular telescopic component 90 is retracted, the torsion spring seat 41 rotates reversely with the torsion spring seat 51 to hold the brake torsion spring 52 tightly, so as to balance part of the load torque and reduce the force on the reduction transmission mechanism 30.

[0060] 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. An electric linear actuator, comprising: Motor; Tubular telescopic member; A transmission device, which transmits the power of the motor to the tubular telescopic component to drive the tubular telescopic component to perform linear motion; The transmission device comprises a screw rod and a transmission nut threadedly engaged with the screw rod, and the transmission nut is connected to the tubular telescopic component; The invention is characterized in that: the transmission device also includes a clutch; the clutch includes a fixed sleeve, a movable sleeve and an elastic member; the fixed sleeve is driven to rotate by the output power of the motor; the movable sleeve is connected to the screw rod; the fixed sleeve and the movable sleeve remain relatively fixed in the circumferential direction when engaged and can move relative to each other axially, allowing the screw rod to move in the extending 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 member acts on the screw rod to maintain its force state in the retracting direction of the tubular telescopic component.

2. The electric push rod 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 realize the engagement of the fixed sleeve and the movable sleeve.

3. The electric push rod according to claim 2, characterized in that: At least one of the first engaging block and the second engaging block has an engaging guide surface for guiding the first engaging block and the second engaging block to achieve engagement.

4. The electric push rod according to claim 3, characterized in that: The fixed sleeve is engaged with the movable sleeve by a ratchet method.

5. The electric push rod according to claim 4, characterized in that: The ratchet teeth of the fixed sleeve and the movable sleeve are the first engagement block and the second engagement block respectively; the inclined surface of the ratchet teeth is the engagement guide surface; and the angle between the engagement guide surface and the axial direction of the fixed sleeve and the movable sleeve is 20-65 degrees.

6. The electric push rod according to claim 3, characterized in that: The fixed sleeve is engaged with the movable sleeve by a pointed spline.

7. The electric push rod according to claim 6, characterized in that: 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 teeth is formed with a sharp corner and the inclined surface of the sharp corner is the engaging guide surface.

8. The electric linear actuator according to claim 1, characterized in that: The transmission device also includes a reduction transmission mechanism having a planetary gear assembly or a worm gear assembly, the sun gear or the worm gear is an input component, and the planetary gear carrier or the worm gear is an output component; the output component is drivingly connected to the fixed sleeve.

9. The electric linear actuator according to claim 8, characterized in that: The screw rod passes through the fixed sleeve; the fixed sleeve and the output component are relatively fixed in the circumferential direction and relatively movable in the axial direction; a thrust bearing is provided at the tail of the electric push rod to resist the tail pull of the electric push rod; the axial thrust borne by the screw rod passes through the output component through the guidance of the clutch and directly reaches the thrust bearing.

10. The electric push rod according to claim 9, characterized in that: A stop ring is provided on the fixed sleeve; an end of the screw rod close to the thrust bearing is connected to a support member; the stop ring is located at an end of the fixed sleeve close to the support member; and the elastic member provides a thrust to move the support member and the fixed sleeve away from each other.

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