Parallel shaft multi-stage transmission structure of electric push rod

Abstract

The invention relates to the technical field of electric push rods, solves the problems of single-side stress and bearing bottleneck, insufficient space efficiency and easy generation of noise and vibration in gear meshing of a traditional parallel-shaft electric push rod, and provides an electric push rod parallel-shaft multistage transmission structure which comprises an electric push rod and a motor, and the electric push rod comprises a front shell and a rear shell; a push rod is arranged in the front shell and is provided with a connecting pipe fitting, and the connecting pipe fitting is connected with a screw rod; an output shaft of the motor is connected with a worm, a duplex shaft is arranged in the rear shell, a worm gear meshed with the worm is arranged in the middle of the duplex shaft, secondary transmission gears are arranged at the two ends of the duplex shaft, a staggered shaft is arranged in the rear shell, a staggered gear meshed with the secondary transmission gears is arranged at the lower end of the staggered shaft, a tertiary transmission gear is arranged at the upper end of the staggered shaft, and a driven gear is arranged at the upper end of the screw. And the driven gear is simultaneously meshed with the three-stage transmission gears on the two sides. The invention has the advantages that the symmetrical load design improves the load capacity, and the compact and efficient parallel shaft layout reduces the operation noise.

Description

Technical Field

[0001] This invention relates to the field of electric linear actuator technology, specifically to an electric linear actuator with a parallel shaft multi-stage transmission structure. Background Technology

[0002] Linear drive is a concept that converts the rotary motion of a DC motor into linear reciprocating motion. A linear drive system is an integration of an electric linear actuator, a switching power supply, a controller, or a panel. It is widely used in mechanical systems for lifting, extending, and angle adjustment. As a linear drive actuator, the electric linear actuator is widely used in various fields such as smart homes, smart healthcare, smart offices, smart kitchens, and industrial automation due to its advantages such as compact structure, precise control, and ease of integration. Its core performance indicators include output thrust, operating speed, noise level, reliability, lifespan, and installation space requirements.

[0003] Traditional electric linear actuator transmission structures, especially those for parallel-axis electric linear actuators, have the following limitations: 1. In common single-stage or asymmetrical multi-stage transmission structures, the final output stage (such as the gear driving the screw) often bears the meshing force on one side. This not only increases the load on key gears and bearings and limits the increase of maximum thrust, but may also cause uneven wear of transmission components, affecting life and smoothness. 2. Although worm gear drives have a high reduction ratio, their axes are usually spatially intersecting, resulting in a more prominent structure in a single dimension. If a larger reduction ratio or higher thrust is required, an additional reduction stage (such as a parallel shaft gear or planetary gear) is needed, which will further increase the overall size and make it difficult to meet the growing demand for ultra-compact push rods. 3. Worm gear meshing and high-speed gear meshing are prone to generating noise and vibration, especially in the case of metal-to-metal hard meshing, which affects the user experience (such as medical beds and household electric furniture). Summary of the Invention

[0004] To address the problems of unilateral force and load-bearing bottlenecks, insufficient space efficiency, and noise and vibration caused by gear meshing in traditional parallel-axis electric linear actuators, this invention provides a multi-stage transmission structure for parallel-axis electric linear actuators.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a multi-stage transmission structure of parallel shaft for electric push rod, including electric push rod and motor, the electric push rod including front housing and rear housing for providing transmission space, the front housing and rear housing are connected by a sealing connection to form a closed transmission cavity; A push rod is slidably provided axially inside the front housing. The push rod extends to the outer side of the front end of the front housing. A connecting pipe is provided at the end of the push rod. The connecting pipe is slidably connected to the front housing. A screw is threadedly connected to the connecting pipe. The screw extends into the hollow push rod and is rotatably connected to the front housing. The motor is fixed to the outside of the rear housing. The motor output shaft extends into the rear housing and is connected to a worm gear. A double coupling is rotatably installed inside the rear housing. A worm wheel meshing with the worm gear is located in the middle of the double coupling. Two-stage transmission gears are symmetrically arranged at both ends of the double coupling. Crossed shafts are symmetrically arranged inside the rear housing and on both sides of the screw. Each crossed shaft has a crossed gear meshing with the two-stage transmission gear at its lower end. A three-stage transmission gear is located at the upper end of the crossed shaft. A driven gear is located at the upper end of the screw. The driven gear meshes with the three-stage transmission gears on both sides simultaneously, forming a parallel-axis multi-stage transmission chain of "motor → worm gear → worm wheel → double coupling → two-stage transmission gear → crossed gear → three-stage transmission gear → driven gear → screw".

[0006] Furthermore, the axis of the screw is parallel to the axis of the worm.

[0007] Furthermore, the topology of the transmission chain formed by the interlaced shafts is arranged symmetrically.

[0008] Furthermore, the material pairing of each gear pair in the transmission chain also includes any of the following combinations: (a) In the pairing of the worm gear (10) and the worm (8), one of the metal parts is replaced by a non-metallic material; (b) In the pairing of the secondary transmission gear (11) and the interlocking gear (13), one of the metal parts is replaced by a non-metallic material; (c) In the pairing of the three-stage transmission gear (14) and the driven gear (15), one of the metal parts is replaced by a non-metallic material.

[0009] The advantages of this invention are: 1. Symmetrical load design: The design of the two-stage transmission gears with symmetrical ends at both ends of the double shaft, the staggered shafts and gears with symmetrical sides, and the driven gear meshing with the three-stage transmission gears on both sides at the same time, makes the load of the final drive screw evenly distributed on both sides, reducing the load on individual gears and bearings, and improving the overall load-bearing capacity and service life. 2. The compact and efficient parallel shaft layout means that all axes of the entire transmission chain (from the motor to the screw) are arranged in parallel (the worm and the screw are parallel, and the shafts of each gear are parallel), which avoids complex spatial interlacing structures, greatly optimizes the utilization of internal space, and makes the overall transmission structure very compact, especially suitable for application scenarios with strict limitations on installation space. 3. Noise reduction: By requiring the replacement of metal parts in key gear pairs (worm gear, secondary gear pair, tertiary gear and driven gear) with non-metallic materials, impact can be effectively absorbed, meshing noise and vibration can be reduced, and the smoothness and quietness of operation can be improved. Attached Figure Description

[0010] Figure 1 This is an exploded structural diagram of the present invention.

[0011] Figure 2 This is a partially enlarged schematic diagram of the explosion structure of the present invention.

[0012] Figure 3 This is a plan view of the transmission structure of the present invention.

[0013] Figure 4 This is an axial sectional view of the screw of the present invention.

[0014] Figure 5 This is a schematic diagram of the structure of the present invention.

[0015] As shown in the figure: 1. Electric push rod; 2. Motor; 3. Front housing; 4. Rear housing; 5. Push rod; 6. Connecting pipe; 7. Screw; 8. Worm gear; 9. Double shaft; 10. Worm wheel; 11. Secondary transmission gear; 12. Interlaced shaft; 13. Interlaced gear; 14. Tertiary transmission gear; 15. Driven gear. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings.

[0017] Combined with appendix Figure 1-5 A multi-stage transmission structure for a parallel shaft of an electric actuator includes an electric actuator 1 and a motor 2. The electric actuator 1 includes a front housing 3 and a rear housing 4, which are sealed together with a sealing ring on the mating surface to form a closed transmission cavity. The rear housing 4 has a reserved mounting seat for the motor 2 to fix the motor 2. The output shaft of the motor 2 is connected to a worm gear 8 via a flat key (the worm gear 8 can be integrally formed with the output shaft).

[0018] Primary transmission: 10 worm gears and 8 worm shafts The two ends of the double-coupling 9 are supported on the rear housing 4 by bearings, and the worm gear 10 in the middle meshes with the worm 8.

[0019] Secondary transmission: parallel gear pair The secondary transmission gears 11 at both ends of the double shaft 9 mesh with the interlocking gears 13 on both sides respectively.

[0020] Three-stage transmission: symmetrical output gear pair The three-stage transmission gear 14 at the upper end of the interlaced shaft 12 meshes with the driven gear 15 at the top of the screw 7, forming a symmetrical force splitting structure.

[0021] Motion conversion mechanism: The upper end of the screw 7 is supported by a bearing within the front housing 3, and the lower end extends into the hollow push rod 5.

[0022] The connecting pipe 6 is embedded in the screw 7 to form a T-shaped thread pair, which converts the rotational motion into the linear motion of the push rod 5.

[0023] In a specific implementation case, motor 2 drives worm 8 to rotate, and after being reduced by worm wheel 10, it drives double shaft 9 to rotate. The secondary transmission gears 11 at both ends of double shaft 9 synchronously drive the interlaced gears 13 on both sides to achieve power splitting. The tertiary transmission gears 14 at the upper end of the interlaced shaft 12 mesh together with the driven gear 15 to drive screw 7 to rotate. The rotation of screw 7 drives the connecting pipe 6 to move linearly, pushing push rod 5 to extend / retract.

[0024] Implementation Case 1: Spur Gear Scheme for Three-Stage Transmission Gears Structural change: Replace all helical gears with spur gears. The three-stage transmission gear 14 and driven gear 15 were modified to use spur gears with a pressure angle of 20° while maintaining the original module and center distance. After comparative testing, it was found that the helical gear scheme has better transmission efficiency and axial force.

[0025] Implementation Case 2: All-Metal Gear Transmission Solution All gear pairs in the transmission chain are made of metal, and the tooth surfaces of the gears are reinforced. They are suitable for high-temperature working environments (such as mechanical gates in steel plants). The measured operating noise of the electric push rod 51 is relatively high.

[0026] Implementation Case 3: Metal-Nonmetal Hybrid Transmission Solution Worm Gear 10 and Worm Gear 8 Set: Adopting a metal worm gear 8 and a POM worm gear 10, the noise is reduced by 12dB; Two-stage gear pair: Metal gear two-stage transmission gear 11 and PA66 interlocking gear 13, resulting in an 8dB noise reduction; Three-stage gear pair: PEEK three-stage gear and metal driven gear 15, resulting in a 6dB reduction in noise; The non-metallic gear mounting holes are all elliptical, and the metal shaft surface is coated with polytetrafluoroethylene to reduce friction.

[0027] Implementation Case 4: All-Non-Metallic Gear Transmission Solution All gear pairs in the transmission chain are made of non-metallic materials to meet the requirements of special working conditions. The overall structural weight is reduced by more than 45%, making it suitable for light working scenarios at normal temperature. In actual operation with small thrust fluctuations, it is stable and has low noise.

[0028] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A multi-stage transmission structure for an electric linear actuator with parallel shafts, characterized in that: It includes an electric push rod (1) and a motor (2). The electric push rod (1) includes a front housing (3) and a rear housing (4) for providing a transmission space. The front housing (3) and the rear housing (4) are connected by a sealed connection to form a closed transmission cavity. A push rod (5) is slidably provided axially inside the front housing (3). The push rod (5) extends to the outer side of the front end of the front housing (3). A connecting pipe (6) is provided at the end of the push rod (5). The connecting pipe (6) is slidably connected to the front housing (3). A screw (7) is threadedly connected inside the connecting pipe (6). The screw (7) extends into the hollow push rod (5). The screw (7) is rotatably connected to the front housing (3). The motor (2) is fixed to the outside of the rear housing (4). The output shaft of the motor (2) extends into the rear housing (4) and is connected to a worm gear (8). A double-coupling shaft (9) is rotatably provided inside the rear housing (4). A worm wheel (10) meshing with the worm gear (8) is provided in the middle of the double-coupling shaft (9). Two-stage transmission gears (11) are symmetrically provided at both ends of the double-coupling shaft (9). Crossed shafts (12) are symmetrically provided inside the rear housing (4) and on both sides of the screw (7). Each crossed shaft (12) has a lower end that is connected to a two-stage transmission gear. (11) Interlocking gears (13), the upper end of the interlocking shaft (12) is provided with a three-stage transmission gear (14), the upper end of the screw (7) is provided with a driven gear (15), the driven gear (15) meshes with the three-stage transmission gears (14) on both sides at the same time, forming a parallel shaft multi-stage transmission chain of "motor (2) → worm (8) → worm wheel (10) → double shaft (9) → two-stage transmission gear (11) → interlocking gear (13) → three-stage transmission gear (14) → driven gear (15) → screw (7)".

2. The electric linear actuator parallel shaft multi-stage transmission structure according to claim 1, characterized in that: The axis of the screw (7) is parallel to the axis of the worm (8).

3. The electric linear actuator parallel shaft multi-stage transmission structure according to claim 1, characterized in that: The topology of the transmission chain formed by the interlaced shafts (12) is arranged in a symmetrical manner.

4. The electric linear actuator parallel shaft multi-stage transmission structure according to claim 1, characterized in that: The material pairing of each gear pair in the transmission chain also includes any of the following combinations: (a) In the pairing of the worm gear (10) and the worm (8), one of the metal parts is replaced by a non-metallic material; (b) In the pairing of the secondary transmission gear (11) and the interlocking gear (13), one of the metal parts is replaced by a non-metallic material; (c) In the pairing of the three-stage transmission gear (14) and the driven gear (15), one of the metal parts is replaced by a non-metallic material.

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