Electric push rod capable of accurately controlling stroke

Abstract

The invention relates to the technical field of electric push rods, in particular to an electric push rod capable of accurately controlling stroke, which comprises a shell, and a transmission assembly is arranged in the shell; the sleeve is connected with one end of the shell; the telescopic assembly is arranged in the sleeve and is in transmission connection with the switch assembly together with the output end of the transmission assembly; the transmission assembly comprises a driving motor, and the driving motor is a motor with double output ends; the travel control assembly is arranged at the tail end of the shell; the stroke control assembly is used for accurately controlling the stroke of the electric push rod; the pressure of the detection assembly is changed by changing the stroke of the detection assembly, high-precision detection of the stroke of the electric push rod is realized by matching the pressure change with the detection element, and the technical problem of low detection precision in the prior art is solved; meanwhile, the stroke control assembly is arranged at the tail end of the electric push rod, the length of the lead is reduced, the diameter size of the electric push rod can be reduced, and the push rod meeting the special size requirement is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric push rods, and particularly to an electric push rod with precise stroke control. Background Art

[0002] The electric push rod adopts worm and worm gear or gear transmission, and realizes linear motion through a lead screw and nut. The stroke control of the electric push rod is detected and controlled by means of mechanical limit, encoder and Hall feedback, PLC and controller, etc.

[0003] Chinese Patent CN202022043505.X discloses a high-load electric push rod, which includes a sleeve assembly, an inner tube assembly sleeved in the sleeve assembly and extending out of the sleeve assembly through the front end, a transmission mechanism for driving the inner tube assembly to perform telescopic motion, and a driving unit fixedly connected to the rear end of the sleeve assembly. The transmission mechanism includes a transmission screw sleeved in the inner tube assembly, and also includes a thrust plate that is installed on the rear end journal of the transmission screw by interference fit and is used for bearing and transmitting axial load force; by optimizing the design of a new type of elastic retaining ring, that is, the thrust plate, and installing it on the rear end of the transmission screw by interference fit, the thrust plate can provide large axial and radial pre-tightening forces, effectively replace the bearing of the original push plate, reduce the wear of parts, and has a simple structure, low cost and convenient and time-saving installation.

[0004] However, the control component of this technical solution is between the motor and the lead screw, and the control wire needs to be threaded along the inner wall of the sleeve assembly. During the assembly process, due to manual operation errors, the lead wire is easily squeezed and ground, resulting in wire breakage, affecting the detection accuracy or losing the detection accuracy, and the high-precision detection of the stroke of the electric push rod cannot be realized. Summary of the Invention

[0005] The purpose of the present invention is to provide an electric push rod with precise stroke control for the deficiencies of the prior art. By changing the stroke of the detection component, the pressure of the detection component is changed, and the pressure change is combined with the detection element to realize the high-precision detection of the stroke of the electric push rod. Compared with the Hall detection method of the prior art, the present application can confirm the specific position of the electric push rod after being powered on again after power failure, avoiding the technical problem that the Hall detection method cannot correctly judge the position of the electric push rod after power failure. At the same time, the present application sets the stroke control component at the tail end of the electric push rod, which not only reduces the length of the lead wire, but also can reduce the diameter size of the electric push rod, realizing a push rod that meets special size requirements in the present application.

[0006] To achieve the above object, the present invention provides the following technical solutions: An electric push rod with precise stroke control, comprising: A housing, in which a transmission component is provided; A sleeve, which is connected to one end of the housing; A telescopic assembly, which is arranged inside the sleeve and is in transmission connection with the output end of the transmission assembly; A switch assembly for controlling the stroke of the telescopic assembly; The transmission assembly includes a driving motor, and the driving motor is a motor with double output ends; the telescopic assembly is in transmission connection with the driving motor through a reducer; It further includes a stroke control assembly arranged at the tail end of the housing and in transmission connection with the transmission assembly; the stroke control assembly is used to accurately control the stroke of the electric push rod.

[0007] As an improvement, the stroke control assembly converts the rotation distance of the motor into a pressure change, and determines the actual stroke of the electric push rod by detecting the pressure magnitude.

[0008] As an improvement, the stroke control assembly includes: A support shaft, which is installed at the end of the driving motor; A gear shaft, which is rotatably installed on the support shaft and has external teeth thereon; A worm, which is sleeved on the gear shaft and rotates synchronously with the gear shaft; A multi-stage reduction assembly, the input end of which is connected to the output end of the driving motor, and the output end is in transmission connection with the gear shaft; And a detection assembly, which is used to detect the rotational displacement of the driving motor.

[0009] As an improvement, the stroke control assembly drives a volume change of the detection assembly, changes the internal pressure of the detection assembly, and thus determines the stroke of the electric push rod.

[0010] As an improvement, the detection assembly includes: A detection base, which is installed on one side of the driving motor; A detection element, which is installed at the inner bottom end of the detection base and detects the stroke of the electric push rod through a pressure change; A guide cylinder, which is installed on one side of the detection base and forms an internal sealed space with the detection base, and hydraulic oil is provided in the sealed space; A push rod piston, which is slidably arranged on the inner wall of the guide cylinder, and one end thereof passes through the guide cylinder, and the push rod piston reciprocates to change the pressure of the sealed space; And an adjusting block, which is in transmission connection with the worm and is connected to the push rod piston at the other end.

[0011] As an improvement, the detection component further includes a guide rod disposed on the outer wall of the guide cylinder; the adjusting block is slidably disposed between the guide rods.

[0012] As an improvement, the multi-stage speed reduction component is formed by the meshing of multi-stage gears, and includes a transmission gear connected to the output end of the driving motor in the middle, and multiple groups of first large gears and first small gears connected coaxially.

[0013] As an improvement, the telescopic component includes: A lead screw, the lead screw is connected to the output end of the transmission component; A transmission nut, the transmission nut is in threaded transmission connection with the lead screw, and the outside of the transmission nut is clamped and slidably connected to the sleeve; And a telescopic tube, the telescopic tube is connected to the transmission nut and reciprocates with the transmission nut.

[0014] As an improvement, the switch component includes a limit switch for limiting the maximum stroke and the minimum stroke of the telescopic tube.

[0015] As an improvement, it further includes a protection component for isolating the stroke control component. The protection component includes a bottom plate connected to the driving motor, a protective cover covering the stroke control component, and a groove for threading a wire provided on the outside of the protective cover.

[0016] The beneficial effects of the present invention are as follows: (1) By arranging the forming control component at the tail end of the electric push rod, the present invention reduces the lead length of the stroke control component, avoiding the problem in the prior art that when the wire is routed along the inner wall side of the electric push rod, during the assembly and use of the electric push rod, due to operational errors, the wire skin of the wire is damaged, which causes damage to the lead of the control component, and external factors affect the signal transmission accuracy, resulting in low stroke control accuracy of the electric push rod.

[0017] (2) By arranging the forming control component at the tail end of the push rod, the present invention does not need to route the wire inside the push rod, and can reduce the diameter size of the push rod. For working conditions with special size requirements, under the same size conditions, a larger output power can be provided.

[0018] (3) By converting the linear motion of the driving motor into the stroke of the detection component, and changing the pressure size of the detection component by changing the stroke of the detection component, and using the pressure change to cooperate with the detection element, the present invention realizes high-precision detection of the stroke of the electric push rod. Compared with the prior art using Hall detection, the present application can confirm the specific position of the electric push rod after being powered on again after power-off, avoiding the technical problem that the Hall detection method cannot correctly judge the position of the electric push rod after power-off.

[0019] (4) The present invention converts the rotational distance of the motor into the stroke change of the detection component through a multi-stage deceleration structure, and uses a dual-output motor to drive the lead screw transmission at one end and synchronously detect and control the transmission distance of the lead screw at the other end.

[0020] (5) The present invention drives the push rod piston to reciprocate through the adjustment block to realize the pressure change in the closed space, and cooperates with the detection element for detecting the pressure change in the closed space to accurately detect the stroke position of the electric push rod, and cooperates with the control board to accurately control the stroke of the electric push rod.

[0021] In summary, the present invention has the advantages of high detection accuracy and small external influencing factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a schematic cross-sectional view of the overall structure of the present invention; Figure 3 is a schematic diagram of the protection component of the present invention; Figure 4 is a schematic diagram of the stroke control component of the present invention; Figure 5 is of the present invention Figure 2 enlarged partial view at I in; Figure 6 is of the present invention Figure 2 enlarged partial view at II in; Figure 7 is a schematic cross-sectional view of the stroke control component of the present invention.

[0023] Reference Signs: 1. Housing; 2. Transmission Component; 21. Driving Motor; 22. Reducer; 3. Sleeve; 31. Positioning Member; 32. Guide Ring; 33. Sealing Ring; 4. Telescopic Component; 41. Lead Screw; 42. Transmission Nut; 43. Telescopic Tube; 5. Switch Component; 6. Stroke Control Component; 61. Support Shaft; 62. Gear Shaft; 63. Worm; 64. Multi-stage Deceleration Component; 641. Transmission Gear; 642. First Large Gear; 643. First Small Gear; 65. Detection Component; 651. Detection Base; 652. Detection Element; 653. Guide Tube; 654. Push Rod Piston; 655. Adjustment Block; 656. Guide Rod; 7. Protection Component; 71. Base Plate; 72. Protective Cover; 721. Groove. DETAILED DESCRIPTION OF THE INVENTION

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0026] Embodiment 1 As Figure 1 - Figure 2 shown, this embodiment provides an electric push rod for precisely controlling the stroke, including: A housing 1, in which a transmission component 2 is provided; A sleeve 3, which is connected to one end of the housing 1; A telescopic component 4, which is arranged in the sleeve 3 and is in transmission connection with the output end of the transmission component 2. By controlling the extension / retraction of the telescopic tube 43 through the transmission component 2, the stroke of the electric push rod is changed; the sleeve 3 guides the reciprocating movement of the telescopic component 4; A switch component 5, which is arranged between the telescopic component 4 and the transmission component 2 and is used to control the stroke of the telescopic component 4; The transmission component 2 includes: A driving motor 21, which is a motor with double output ends; the telescopic component 4 is in transmission connection with the driving motor 21 through a speed reducer 22; specifically, by adopting a driving motor 21 with double outputs, precise detection of the motor rotation is realized, that is, both ends of the motor are connected to the detection mechanism and the driving mechanism at the same time, realizing synchronous detection and transmission, so as to realize precise detection of the stroke of the electric push rod; It further includes a stroke control component 6 disposed at the tail end of the housing 1 and drivingly connected to the transmission component 2; the stroke control component 6 is used to accurately control the stroke of the electric push rod.

[0027] It should be noted that the stroke control component 6 is installed at the tail end of the housing 1, reducing the length of the connecting wire of the stroke control component 6 and avoiding problems such as extrusion damage to the wire during assembly and application due to too long a wire, which affects the stroke control accuracy of the electric push rod.

[0028] Preferably, the stroke control component 6 converts the rotation distance of the motor into a pressure change, and determines the actual stroke of the electric push rod by detecting the pressure magnitude.

[0029] Specifically, in this application, the rotation distance of the motor is converted into the stroke of the hydraulic component through a reduction structure, thereby changing the pressure magnitude inside the hydraulic component. The pressure sensing element provided inside the hydraulic component detects different pressure magnitudes, thereby judging the specific stroke of the electric push rod. At the same time, how much stroke distance is deduced from different pressure magnitudes can be calculated by the engineer before leaving the factory and informed to the user of the specific parameters, or the parameter data can be written into the processor for real-time retrieval.

[0030] Preferably, the telescopic component 4 includes: A lead screw 41, the lead screw 41 is connected to the output end of the transmission component 2; A transmission nut 42, the transmission nut 42 is in threaded transmission connection with the lead screw 41, and the outer side of the transmission nut 42 is clamped and slidably connected to the sleeve 3. Specifically, a guide groove is provided on the transmission nut 42, and a guide protrusion is provided on the inner wall of the sleeve 3. The guide groove is slidably provided on the guide protrusion, so that the transmission nut 42 makes a reciprocating linear motion along the sleeve 3, avoiding the rotation of the transmission nut 42, thereby driving the telescopic tube 43 to reciprocate. A telescopic tube 43, the telescopic tube 43 is connected to the transmission nut 42 and reciprocates with the transmission nut 42.

[0031] Furthermore, as Figure 5 shown, a positioning member 31 for guiding and sealing the telescopic tube 43 is further provided at the end of the sleeve 3. The positioning member 31 is connected to the sleeve 3, the inner wall of the positioning member 31 abuts against the telescopic tube 43, and a plurality of sealing rings 33 and guide rings 32 are provided between the two, realizing high-precision guiding and sealing of the telescopic tube 43.

[0032] Preferably, the switch assembly 5 includes limit switches for restricting the maximum and minimum strokes of the telescopic tube 43. Specifically, the maximum-stroke limit switch is provided at the extended end of the telescopic tube 43. When the telescopic tube 43 extends outward and presses the maximum-stroke limit switch, the telescopic tube 43 triggers a protection mechanism to prevent it from continuing to extend and damaging the electric push rod. Similarly, when the telescopic tube 43 runs to the minimum stroke, it presses the minimum-stroke limit switch to stop the electric push rod from running, preventing the telescopic tube 43 from damaging the internal structure of the push rod piston 654.

[0033] Embodiment 2 As Figure 4 , Figure 6 , Figure 7 shown, where the same or corresponding components as in Embodiment 1 are denoted by the corresponding reference numerals in Embodiment 1. For the sake of simplicity, only the differences from Embodiment 1 will be described below. The differences between this Embodiment 2 and Embodiment 1 are as follows: In this embodiment, the stroke control assembly 6 includes: A support shaft 61, which is installed at the end of the drive motor 21; A gear shaft 62, which is rotatably installed on the support shaft 61 and has external teeth thereon; A worm 63, which is sleeved on the gear shaft 62 and rotates synchronously with the gear shaft 62; specifically, a flat structure is provided on the outer diameter surface of one end of the gear shaft 62, and a flat groove adapted to the flat structure is provided in the inner diameter of the worm 63, so that the worm 63 rotates synchronously with the gear shaft 62; A multi-stage reduction assembly 64, whose input end is connected to the output end of the drive motor 21, and the output end is in transmission connection with the gear shaft 62; And a detection assembly 65, which is used to detect the rotational displacement of the drive motor 21.

[0034] Preferably, the stroke control assembly 6 determines the stroke of the electric push rod by driving a change in the volume of the detection assembly 65 and changing the internal pressure of the detection assembly 65.

[0035] Embodiment 3 As Figure 7 shown, where the same or corresponding components as in Embodiment 1 are denoted by the corresponding reference numerals in Embodiment 1. For the sake of simplicity, only the differences from Embodiment 1 will be described below. The differences between this Embodiment 3 and Embodiment 1 are as follows: In this embodiment, the detection assembly 65 includes: A detection base 651, which is installed on one side of the drive motor 21; The detection element 652 is installed at the inner bottom end of the detection base 651, and detects the stroke of the electric push rod through pressure changes; specifically, the detection element 652 can adopt a pressure sensor, which detects the internal pressure change through the pressure sensor, transmits the data to the PCB board for identification, and thus determines the stroke position of the electric push rod; the pressure sensor can adopt one or more combinations of strain gauge pressure sensors, piezoelectric sensors, capacitive pressure sensors, etc., to detect the pressure change in the confined space; A guide cylinder 653, wherein the guide cylinder 653 is installed at one side of the detection base 651 and forms an internal closed space with the detection base 651, and hydraulic oil is provided in the closed space; A push rod piston 654, wherein the push rod piston 654 is slidably disposed on the inner wall of the guide cylinder 653, one end of the push rod piston 654 passes through the guide cylinder 653, and the push rod piston 654 reciprocates to change the pressure of the enclosed space; The adjusting block 655 is transmission-connected to the worm 63 , and the other end of the adjusting block 655 is connected to the push rod piston 654 .

[0036] It should be noted that the rotation of the worm 63 drives the adjustment block 655 to move back and forth, thereby driving the push rod piston 654 to move back and forth, so that the circumferential motion of the worm 63 is converted into the linear motion of the adjustment block 655, thereby changing the pressure in the enclosed space, and determining the stroke of the electric push rod through the pressure change detected by the detection element 652. The method of determining the stroke of the push rod piston 654 in this application is significantly different from the method of using limit switches and Hall detection positions in the prior art. Specifically, the Hall detection position is a relative position detection. When encountering a power-off condition, after the electric push rod is turned on again, the Hall detection cannot determine the real-time position of the electric push rod, that is, the Hall sensor does not know the position of the push rod piston 654 after the power is turned on again, resulting in the inability to perform subsequent judgments normally, such as disengagement or jamming.

[0037] In addition, the Hall sensor has high requirements on environmental conditions. For some working conditions with strong magnetic fields that greatly interfere with the normal operation of the Hall sensor, the Hall sensor cannot perform high-precision stroke detection.

[0038] The present application uses pressure changes to determine the stroke position of the push rod piston 654, which has high detection accuracy, is suitable for special working conditions, and the control accuracy is less affected by external factors.

[0039] Furthermore, the detection assembly 65 also includes guide rods 656 disposed on the outer wall of the guide cylinder 653 ; the adjustment block 655 is slidably disposed between the guide rods 656 .

[0040] It should be noted that by setting the guide rod 656, the adjusting block 655 can move smoothly back and forth, improving the stroke control accuracy of the push rod piston 654.

[0041] Embodiment 4 As Figure 4 shown, the same or corresponding components as those in Embodiment 1 are denoted by the corresponding reference numerals in Embodiment 1. For the sake of simplicity, only the differences from Embodiment 1 will be described below. The difference between this Embodiment 4 and Embodiment 1 lies in: In this embodiment, the multi-stage deceleration assembly 64 is formed by the meshing of multi-stage gears, which includes a transmission gear 641 connected to the output end of the drive motor 21 in the middle, and multiple groups of coaxially connected first large gears 642 and first small gears 643.

[0042] It should be noted that the transmission gear 641 meshes with the first large gear 642, the first small gear 643 meshes with the first large gear 642 of another group for transmission, and the first large gear 642 meshes with the first small gear 643 of another group to achieve step-by-step deceleration; the first small gear 643 of the last group meshes with the external teeth on the gear shaft 62, thereby driving the worm 63 to rotate.

[0043] Embodiment 5 As Figure 3 shown, the same or corresponding components as those in Embodiment 1 are denoted by the corresponding reference numerals in Embodiment 1. For the sake of simplicity, only the differences from Embodiment 1 will be described below. The difference between this Embodiment 5 and Embodiment 1 lies in: In this embodiment, a protection assembly 7 for isolating the stroke control assembly 6 is further included. The protection assembly 7 includes a bottom plate 71 connected to the drive motor 21, and a protective cover 72 covering the stroke control assembly 6. A groove 721 for passing the lead wire is provided on the outer side of the protective cover 72, and the lead wire is arranged in the groove 721 to avoid extrusion and wear during the assembly process.

[0044] Specifically, one end of the stroke control assembly 6 passes through the bottom plate 71 and is connected to the drive motor 21. By setting the protection assembly 7, the cleanliness of the operating environment of the stroke control assembly 6 is improved, and the transmission accuracy is improved.

[0045] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric push rod for precisely controlling travel, comprising: A housing (1), wherein a transmission assembly (2) is arranged inside the housing (1); A sleeve (3), the sleeve (3) being connected to one end of the shell (1); A telescopic assembly (4), the telescopic assembly (4) being arranged in the sleeve (3) and being transmission-connected to the output end of the transmission assembly (2); A switch assembly (5) for controlling the travel of the telescopic assembly (4); The invention is characterized in that the transmission assembly (2) comprises a driving motor (21), and the driving motor (21) is a motor with two output ends; the telescopic assembly (4) is connected to the driving motor (21) through a reducer (22); It also comprises a stroke control component (6) which is arranged at the rear end of the housing (1) and is transmission-connected to the transmission component (2); the stroke control component (6) is used to accurately control the stroke of the electric push rod.

2. The electric push rod for accurately controlling the stroke according to claim 1, characterized in that: The stroke control component (6) converts the rotation distance of the motor into a pressure change, and determines the actual stroke of the electric push rod by detecting the pressure.

3. The electric push rod for accurately controlling the stroke according to claim 2, characterized in that: The stroke control component (6) comprises: A support shaft (61), the support shaft (61) being mounted on an end of the drive motor (21); a gear shaft (62), the gear shaft (62) being rotatably mounted on the support shaft (61) and having external teeth thereon; a worm (63), wherein the worm (63) is sleeved on the gear shaft (62) and rotates synchronously with the gear shaft (62); A multi-stage reduction assembly (64), wherein an input end of the multi-stage reduction assembly (64) is connected to an output end of the drive motor (21), and an output end is drivingly connected to the gear shaft (62); And a detection component (65), wherein the detection component (65) is used to detect the rotational displacement of the drive motor (21).

4. The electric push rod for accurately controlling the stroke according to claim 3, characterized in that: The stroke control component (6) drives the volume of the detection component (65) to change, thereby changing the internal pressure of the detection component (65), thereby determining the stroke of the electric push rod.

5. The electric push rod for accurately controlling the stroke according to claim 4, characterized in that: The detection component (65) comprises: A detection base (651), the detection base (651) being mounted on one side of the drive motor (21); A detection element (652), the detection element (652) being mounted on the inner bottom end of the detection base (651) and detecting the stroke of the electric push rod through pressure changes; A guide cylinder (653), the guide cylinder (653) being mounted on one side of the detection base (651) and forming an internal closed space with the detection base (651), wherein hydraulic oil is provided in the closed space; A push rod piston (654), wherein the push rod piston (654) is slidably disposed on the inner wall of the guide cylinder (653), one end of the push rod piston (654) passes through the guide cylinder (653), and the push rod piston (654) reciprocates to change the pressure of the closed space; and an adjusting block (655), wherein the adjusting block (655) is drivingly connected to the worm (63) and the other end is connected to the push rod piston (654).

6. The electric push rod for accurately controlling the stroke according to claim 5, characterized in that: The detection assembly (65) further comprises guide rods (656) arranged on the outer wall of the guide cylinder (653); the adjustment block (655) is slidably arranged between the guide rods (656).

7. The electric push rod for accurately controlling the stroke according to claim 3, characterized in that: The multi-stage reduction assembly (64) is formed by a plurality of gears meshing with each other, and comprises a transmission gear (641) whose middle portion is connected to the output end of the drive motor (21), and a plurality of sets of first large gears (642) and first small gears (643) that are coaxially connected.

8. The electric push rod for precisely controlling the stroke according to claim 1, characterized in that: The telescopic assembly (4) comprises: A screw rod (41), the screw rod (41) being connected to an output end of the transmission assembly (2); A transmission nut (42), the transmission nut (42) being threadedly connected to the screw rod (41), and the outer side of the transmission nut (42) being slidably connected to the sleeve (3); and a telescopic tube (43), wherein the telescopic tube (43) is connected to the driving nut (42) and reciprocates along with the driving nut (42).

9. The electric push rod for accurately controlling the stroke according to claim 8, characterized in that: The switch assembly (5) comprises a limit switch for limiting the maximum stroke and the minimum stroke of the telescopic tube (43).

10. The electric push rod for precisely controlling the stroke according to claim 1, characterized in that: The invention also comprises a protective component (7) for isolating the stroke control component (6), the protective component (7) comprising a base plate (71) connected to the drive motor (21), a protective cover (72) covering the stroke control component (6), and a groove (721) for passing a wire is provided on the outer side of the protective cover (72).

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