Miniature electric push rod structure

Abstract

A miniature electric push rod structure provided by the present invention comprises a shell, a stator, a rotor, a telescopic rod and a brushless stepping driver, the stator is fixed in the shell, a coil assembly is wound on the stator, the rotor is coaxially and rotatably installed in the stator, the rotor is of a hollow barrel-shaped structure, an internal thread is processed on the inner wall of the rotor, and the brushless stepping driver is arranged in the shell. The lower end of the telescopic rod is inserted into the hollow cavity of the rotor, external threads matched with the internal threads of the rotor are machined on the periphery of the lower end of the telescopic rod, so that the telescopic rod and the rotor form a lead screw nut transmission structure, and a brushless stepping driver is further installed at the bottom of the shell. The brushless stepping driver is used for adjusting the output current to control the extending and retracting stroke and position of the telescopic rod relative to the shell. The telescopic rod transmission assembly is directly arranged in the motor rotor, the structure is extremely simplified and miniaturized, and meanwhile the motor has the advantages of being high in precision and adjustable in speed.

Description

Technical Field

[0001] This invention relates to the field of electric linear actuator technology, and more particularly to a miniature electric linear actuator structure. Background Technology

[0002] An electric linear actuator is an electrically driven device that converts the rotary motion of a motor into the linear reciprocating motion of a linear actuator. It is widely used in home, industrial, medical, and robotic applications. Traditional electric linear actuators typically employ a transmission configuration of "motor + reducer + lead screw / trapezoidal lead screw." This structure has the following disadvantages: Complex structure and large size: intermediate transmission components such as reducers and couplings occupy a lot of space, making miniaturization difficult.

[0003] Limited control precision: Ordinary DC motors require complex closed-loop control systems (such as photoelectric encoders) to achieve precise positioning, which are complex and costly.

[0004] Slow response speed: The dynamic response performance of the system is affected by the presence of the speed reducer.

[0005] Difficulty in miniaturization: In confined spaces such as robotic dexterity hands, the size and weight of traditional actuators become the main obstacles to their application.

[0006] Therefore, there is an urgent need in this field for an electric linear actuator solution that is highly integrated in structure, has high control precision, fast response speed, and is easy to miniaturize. Summary of the Invention

[0007] This invention provides a miniature electric linear actuator structure. By technically modifying the existing linear actuator structure, it solves the problems of the existing electric linear actuator structure being relatively complex, occupying a large space, and having low adjustment accuracy.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A miniature electric actuator structure includes a housing, a stator, a rotor, a telescopic rod, and a brushless stepper driver. The stator is fixed inside the housing and has a coil assembly wound around it. A rotor is coaxially mounted inside the stator. The rotor has a hollow barrel structure with internal threads machined on its inner wall. The lower end of the telescopic rod is inserted into the hollow cavity of the rotor, and the outer circumference of the lower end of the telescopic rod is machined with external threads that mate with the internal threads of the rotor, so that the telescopic rod and the rotor form a screw-nut transmission structure. A brushless stepper driver is also installed at the bottom of the housing. The brushless stepper driver is electrically connected to the coil assembly and is used to adjust the output current to control the extension and retraction stroke and position of the telescopic rod relative to the housing.

[0009] Preferably, the rotor is rotatably mounted within the housing via at least one bearing.

[0010] Preferably, the upper end of the outer casing is provided with a guide bushing for radially guiding the telescopic rod.

[0011] Preferably, the upper end of the telescopic rod is equipped with a connector for connecting an external load.

[0012] Preferably, a limiting block is also installed inside the hollow cavity of the rotor. The limiting block is located on the upper and lower sides of the internal thread of the rotor, and the limiting block is used to limit the extension rod by contacting the lower end of the extension rod when the extension rod is extended or retracted.

[0013] Preferably, the brushless stepper driver is integrated and installed inside the housing, and the brushless stepper driver is electrically connected to the external control system through a connecting cable extending out of the housing.

[0014] Preferably, the above-mentioned electric actuator structure is applied to the drive structure of the dexterous finger joint of a robot.

[0015] The beneficial effects of this invention are as follows: 1. Extreme miniaturization and high integration: This application adopts an internal rotor structure, with the internal thread directly set inside the rotating rotor, realizing a highly integrated design of "motor rotor as nut", with an extremely short transmission chain and extreme compression of axial and radial dimensions.

[0016] 2. High precision and high resolution: The brushless stepper motor itself has angle control characteristics. Its step angle is small. By controlling the number of input pulses, the rotation angle of the rotor can be precisely controlled. Then, by converting the lead screw pitch, the linear displacement of the telescopic rod can be precisely controlled at the micron level.

[0017] 3. Adjustable speed and rapid response: The brushless stepper driver can smoothly adjust the motor speed by changing the pulse frequency, thereby achieving stepless adjustment of the push rod extension speed. At the same time, because the rotor is located in the center and has a small moment of inertia, the system's start-stop and commutation response is very rapid.

[0018] 4. Simple structure and high reliability: The number of parts is greatly reduced and the transmission chain is extremely short. This not only reduces manufacturing costs but also reduces potential failure points and improves the reliability of the entire drive unit.

[0019] 5. High torque and self-locking: The stepper motor can output a large torque at low speed, and combined with the lead screw transmission pair itself has a certain self-locking capability, so that the push rod can maintain its position well when the power is off. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the internal structure of the present invention; Figure 2 This is a schematic diagram of the installation structure of the present invention; Figure 3 This is a schematic diagram of the stator and rotor installation of the present invention; The reference numerals are as follows: 1. Housing; 2. Stator; 3. Rotor; 31. Cavity; 4. Telescopic rod; 41. Lower end; 5. Brushless stepper driver; 6. Coil assembly; 7. Bearing; 8. Guide bushing; 9. Connector; 10. Limiting block. Detailed Implementation

[0021] The specific content of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0022] Please see Figure 1-3 As shown, the present invention provides a miniature electric actuator structure, including a housing 1, a stator 2, a rotor 3, a telescopic rod 4, and a brushless stepper driver 5. The stator 2 is fixed inside the housing 1, and a coil assembly 6 is wound around the stator 2. The rotor 3 is coaxially rotatably mounted inside the stator 2. The rotor 3 has a hollow barrel structure with internal threads machined on its inner wall. The lower end 41 of the telescopic rod 4 is inserted into the hollow cavity 31 of the rotor 3, and the outer circumference of the lower end 41 of the telescopic rod 4 is machined with external threads that mate with the internal threads of the rotor 3, so that the telescopic rod 4 and the rotor 3 form a screw and nut transmission structure. The brushless stepper driver 5 is also installed at the bottom of the housing 1. The brushless stepper driver 5 is electrically connected to the coil assembly 6. The brushless stepper driver 5 is used to adjust the output current to control the extension and retraction stroke and position of the telescopic rod 4 relative to the housing 1.

[0023] The stator 2 is coaxially fixed on the inner wall of the housing 1 by interference fit or bonding. The stator 2 is preferably a toothed iron core structure made of silicon steel sheets, with coil assembly 6 wound on it. The coil assembly 6 is a multi-phase armature winding that is embedded in the toothed slot of the stator 2 according to a certain rule.

[0024] The rotor 3 is a hollow cylindrical structure. The rotor 3 is located on the radial inner side of the stator 2 and is coaxially arranged with the stator 2. The rotor 3 is rotatably supported on the outer shell 1 by at least one bearing 7 at the front and rear. The rotor 3 has a cavity 31 inside, and the inner side of the cavity 31 of the rotor 3 has a tight internal thread, which also functions as a nut. The rotor 3 is usually made of magnetically conductive material, and permanent magnets can be embedded or bonded to its outer periphery. Alternatively, in the case of multi-pole magnetization, the rotor 3 can be made of permanent magnet material.

[0025] The telescopic rod 4 is a slender metal rod with an external thread structure at its lower end 41 that matches the internal thread. During assembly, the lower end of the telescopic rod 4 is screwed into the internal thread hole of the rotor 3 to form a direct transmission connection. The upper end of the telescopic rod 4 extends out of the housing 1 through the guide bushing 8 at the end of the housing 1.

[0026] Furthermore, in order to enable the rotor 3 to rotate relative to the stator 2, the rotor 3 is rotatably mounted in the housing 1 via at least one bearing 7.

[0027] Furthermore, in order to guide and support the telescopic rod 4, a guide bushing 8 is provided at the upper end of the outer casing 1 for radially guiding the telescopic rod 4. The guide bushing 8 also restricts the axial rotation of the telescopic rod 4, enabling it to extend and retract.

[0028] Furthermore, a connector 9 for connecting an external load is installed at the upper end of the telescopic rod 4.

[0029] Furthermore, a limiting block 10 is also installed inside the hollow cavity 31 of the rotor 3. The limiting block 10 is located on the upper and lower sides of the internal thread of the rotor 3, and the limiting block 10 is used to limit the extension rod 4 by contacting the lower end 41 of the extension rod 4 when the extension rod 4 extends or retracts.

[0030] The limiting block 10 is detachably connected to the rotor 3, which facilitates the installation of the telescopic rod 4 in the inner cavity of the rotor 3.

[0031] Furthermore, the brushless stepper driver 5 is integrated and installed inside the housing 1, and the brushless stepper driver 5 is electrically connected to the external control system through a connecting cable extending out of the housing 1.

[0032] The brushless stepper driver 5 is electrically connected to the coil assembly 6 inside the housing 1 via wires. The driver receives control signals from the host computer and outputs excitation current to each phase of the coil assembly 6 in a preset sequence. The current generates a rotating magnetic field in the windings of the coil assembly 6, driving the rotor 3 located at the center to rotate.

[0033] Each pulse signal drives rotor 3 to rotate by a fixed step angle. By controlling the number and frequency of pulses, the displacement and speed of telescopic rod 4 can be precisely controlled.

[0034] During work: Extension: The brushless stepper driver 5 drives the coil assembly 6, causing the rotor 3 to rotate in one direction. Since the telescopic rod 4 cannot rotate due to the radial constraint of the guide bushing 8, according to the screw drive principle, the rotation of the rotor 3 will be converted into the upward linear extension motion of the telescopic rod 4.

[0035] Retraction: The brushless stepper driver 5 reverses the drive phase sequence, causing the rotor 3 to rotate in the opposite direction, and the telescopic rod 4 to retract downwards in a straight line.

[0036] Stop and Hold: Stop sending pulses, and the brushless stepper motor will remain in its current position, generating a holding torque to lock the telescopic rod 4.

[0037] Furthermore, the aforementioned electric actuator structure is applied to the drive structure of the dexterous finger joints of robots.

[0038] This application creates an extremely compact "motor-push rod" integrated unit by adopting an internal rotor 3 structure and integrating the transmission thread inside the rotor 3, which has broad application prospects in the field of micro-automation such as robot dexterous hands, precision medical devices, and optical focusing mechanisms.

[0039] This invention has the following characteristics: Extreme miniaturization and high integration: This application adopts an internal rotor 3 structure, with the internal thread directly set inside the rotating rotor 3, realizing a highly integrated design of "motor rotor 3 as nut", with an extremely short transmission chain and extreme compression of axial and radial dimensions.

[0040] High precision and high resolution: The brushless stepper motor itself has angle control characteristics. Its step angle is small. By controlling the number of input pulses, the rotation angle of rotor 3 can be precisely controlled. Then, by converting the lead screw pitch, the linear displacement of telescopic rod 4 can be precisely controlled at the micron level.

[0041] Adjustable speed and rapid response: The brushless stepper driver 5 can smoothly adjust the motor speed by changing the pulse frequency, thereby achieving stepless adjustment of the push rod extension and retraction speed. At the same time, since the rotor 3 is located in the center and has a small moment of inertia, the system's start-stop and commutation response is very rapid.

[0042] Simple structure and high reliability: The number of parts is greatly reduced and the transmission chain is extremely short, which not only reduces manufacturing costs but also reduces potential failure points and improves the reliability of the entire drive unit.

[0043] High torque and self-locking capability: The stepper motor can output a large torque at low speed, and combined with the lead screw transmission pair itself has a certain self-locking capability, the push rod can maintain its position well even when the power is off.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0045] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art. In addition, the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0046] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A miniature electric actuator structure, characterized in that, The device includes a housing, a stator, a rotor, a telescopic rod, and a brushless stepper driver. The stator is fixed inside the housing and has a coil assembly wound around it. A rotor is coaxially mounted inside the stator and has a hollow barrel-shaped structure with internal threads machined on its inner wall. The lower end of the telescopic rod is inserted into the hollow cavity of the rotor, and the outer circumference of the lower end of the telescopic rod has an external thread that matches the internal thread of the rotor, so that the telescopic rod and the rotor form a screw and nut transmission structure. A brushless stepper driver is also installed at the bottom of the housing. The brushless stepper driver is electrically connected to the coil assembly and is used to adjust the output current to control the extension and retraction stroke and position of the telescopic rod relative to the housing.

2. The miniature electric actuator structure according to claim 1, characterized in that, The rotor is rotatably mounted inside the housing via at least one bearing.

3. The miniature electric actuator structure according to claim 1, characterized in that, The upper end of the outer casing is provided with a guide bushing for radially guiding the telescopic rod.

4. The miniature electric actuator structure according to claim 1, characterized in that, The upper end of the telescopic rod is equipped with a connector for connecting to an external load.

5. The miniature electric actuator structure according to claim 1, characterized in that, The rotor's hollow cavity is also equipped with a limiting block, which is located on the upper and lower sides of the rotor's internal thread. The limiting block is used to limit the extension rod by contacting the lower end of the extension rod when the extension rod extends or retracts.

6. The miniature electric actuator structure according to claim 1, characterized in that, The brushless stepper driver is integrated and installed inside the housing, and the brushless stepper driver is electrically connected to the external control system through a connecting cable that passes through the housing.

7. A miniature electric actuator structure according to any one of claims 1-6, characterized in that, The aforementioned electric actuator structure is used in the drive structure of the dexterous finger joints of robots.

Images