Waterproof and dustproof electric push rod

Abstract

The present application relates to the field of push rod, in particular to a waterproof and dustproof electric push rod, including drive module, outer tube assembly, inner tube, screw rod, sliding nut, wherein the screw rod and the inner tube are located in the outer tube assembly, the sliding nut is movably assembled on the screw rod, the drive module is drivingly connected with the screw rod, the inner tube is sleeved on the limiting nut and extends to the outside of the outer tube assembly or retracts into the outer tube assembly along the length direction of the screw rod, a waterproof and dustproof module is clamped between the inner tube and the outer tube assembly, wherein the waterproof and dustproof module includes single-lip oil seal, first anti-swing ring, piston oil seal and second anti-swing ring arranged in sequence along the retracting direction of the inner tube, when the inner tube retracts, the inner circle of the single-lip oil seal, the first anti-swing ring, the piston oil seal and the second anti-swing ring is tightly attached to the outer side wall of the inner tube, the single-lip oil seal plays a role in scraping the dirt (dust, sand, etc.) on the surface of the inner tube, and the internal piston oil seal has waterproof and dustproof effect.

Description

Technical Field

[0001] This invention relates to the field of linear actuators, and more particularly to a waterproof and dustproof electric linear actuator. Background Technology

[0002] An electric linear actuator is an electrically driven device that converts the rotary motion of an electric motor into the linear reciprocating motion of a linear actuator. It can be used as an actuator in various simple or complex processes to achieve remote, centralized, or automated control. It is widely used in motion drive units in industries such as home appliances, kitchenware, medical devices, and automobiles.

[0003] Existing electric linear actuators do not have corresponding waterproof or dustproof structures. Due to the varied operating environments of electric linear actuators, the outer wall of the actuator exposed to the outdoor environment will inevitably accumulate a certain amount of mud, sand, moisture, and dust. When the motor drives the actuator to retract, the mud, sand, moisture, and dust on the outer wall of the actuator will directly enter the actuator's interior. Over time, this can lead to moisture corrosion of the internal structure or internal circuitry, and can also easily cause rust and other issues that affect normal operation.

[0004] Therefore, the inventors dedicated themselves to designing a waterproof and dustproof electric actuator to solve the above problems. Summary of the Invention

[0005] To solve the above problems, the present invention provides a waterproof and dustproof electric actuator. By setting a single-lip oil seal, a first anti-sway ring, a piston oil seal, and a second anti-sway ring, the inner rings of the single-lip oil seal, the first anti-sway ring, the piston oil seal, and the second anti-sway ring are tightly attached to the outer wall of the inner tube. When the inner tube retracts, because the inner rings of the single-lip oil seal, the first anti-sway ring, the piston oil seal, and the second anti-sway ring are tightly attached to the outer wall of the inner tube, the single-lip oil seal can scrape off dirt (dust, mud, etc.) from the surface of the inner tube, and the internal piston oil seal can provide waterproof and dustproof protection.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a waterproof and dustproof electric push rod, comprising a drive module, an outer tube assembly, an inner tube, a lead screw, and a sliding nut, wherein the lead screw and the inner tube are both located inside the outer tube assembly, and the sliding nut is movably mounted on the lead screw. The drive module is drivenly connected to the lead screw. The inner tube is sleeved on the limiting nut and extends out of the outer tube assembly or retracts into the outer tube assembly along the length direction of the lead screw. A waterproof and dustproof module is clamped between the inner tube and the outer tube assembly, wherein the waterproof and dustproof module comprises a single-lip oil seal, a first anti-sway ring, a piston oil seal, and a second anti-sway ring arranged sequentially along the retraction direction of the inner tube. The inner rings of the single-lip oil seal, the first anti-sway ring, the piston oil seal, and the second anti-sway ring are tightly fitted to the outer wall of the inner tube.

[0007] Furthermore, the inner walls of the first anti-sway ring and the second anti-sway ring are provided with several threaded oil storage grooves, and the threaded oil storage grooves and the outer wall of the inner tube form an oil storage cavity.

[0008] Furthermore, the outer tube assembly includes an outer tube body and a fixed end cap, wherein the front end of the outer tube body is provided with an opening, and the fixed end cap covers the opening, and the center of the fixed end cap is provided with an outlet for the inner tube to pass through.

[0009] Furthermore, the inner wall of the outer tube body is provided with multiple sliding teeth at intervals; the sliding nut includes a sliding assembly and a sliding sleeve. The inner wall of the sliding assembly is provided with an internal thread, one end of the sliding assembly is provided with an external thread, the sliding sleeve is sleeved on the other end of the sliding assembly, and the outer wall of the sliding sleeve is provided with multiple sliding grooves. Each sliding groove is arranged along the axial direction of the sliding sleeve, and the multiple sliding teeth of the outer tube and the multiple sliding grooves of the sliding sleeve are matched one by one.

[0010] Furthermore, an oil seal mounting slot is provided on the back of the fixed end cap corresponding to the outlet position, wherein the single-lip oil seal is sealed and mounted in the oil seal mounting slot by a sealing ring, and the surface of the oil seal mounting slot is covered by a sealing cap.

[0011] Furthermore, the sliding teeth of the outer tube body are tightly fitted with the outer rings of the first anti-sway ring, the piston oil seal, and the second anti-sway ring.

[0012] Furthermore, the sliding assembly includes a slider and a threaded sleeve. Both the slider and the threaded sleeve are annular. The internal thread is provided on the inner wall of the threaded sleeve. The slider is sleeved on the outside of the threaded sleeve. The slider and the threaded sleeve are positioned by two positioning screws. The two positioning screws are axially located between the slider and the threaded sleeve. A part of the same positioning screw is located on the inner wall groove of the slider, and the other part of the positioning screw is located on the outer wall groove of the threaded sleeve. The two positioning screws are located on the end faces of the slider and the threaded sleeve and are arranged opposite to each other.

[0013] Furthermore, the external thread is located on the outer wall of the slider. The outer wall of the slider at the end away from its external thread is provided with multiple side grooves, multiple grooves and an annular limiting platform. The multiple side grooves are arranged along the axial direction of the slider, the multiple grooves are arranged along the radial direction of the slider, the multiple side grooves and the multiple grooves are intersecting and communicating, and the limiting platform is located between the multiple grooves and the external thread.

[0014] Furthermore, the inner wall of the sliding sleeve is rotated and limited to the outer wall of the slider. The outer wall of the sliding sleeve extends outward to a limiting part. Multiple material removal holes are provided on the end face of the sliding sleeve. When the sliding sleeve is fitted onto the slider, the external thread and the limiting platform on the slider are located outside the sliding sleeve.

[0015] Furthermore, the inner wall of the outer tube body is also provided with two hanging grooves and a positioning part. Multiple sliding teeth, two hanging grooves and positioning part are all arranged along the axial direction of the outer tube body. A fixed frame is hung on the inner wall of the outer tube body along its axial direction. The two ends of the fixed frame are respectively provided with long strip-shaped hanging platforms. The two hanging platforms are respectively matched with the two hanging grooves of the outer tube body. The end of the fixed frame away from the outer tube body is provided with a positioning groove. The positioning groove is matched with the positioning part of the outer tube body. Micro switches are fixed at both ends of the fixed frame. The sliding sleeve 1 is located between the two micro switches. The limiting part of the sliding sleeve is located on the side of the fixed frame.

[0016] The beneficial effects of the present invention are as follows: 1. The drive module drives the lead screw to rotate, and the lead screw drives the entire sliding nut to slide back and forth in the outer tube, thereby realizing the extension and retraction of the inner tube. At the same time, in this application, the waterproof and dustproof module includes a single-lip oil seal, a first anti-sway ring, a piston oil seal, and a second anti-sway ring arranged in sequence along the retraction direction of the inner tube. When the inner tube retracts, since the inner rings of the single-lip oil seal, the first anti-sway ring, the piston oil seal, and the second anti-sway ring are in close contact with the outer wall of the inner tube, the single-lip oil seal plays a role in scraping off dirt (dust, mud, etc.) on the surface of the inner tube, and the internal piston oil seal plays a role in waterproofing and dustproofing.

[0017] 2. In addition, the inner walls of the first and second anti-sway rings are provided with several threaded oil reservoirs. Assuming a single-lip oil seal is used, sand and dust need to move slowly upwards through the threaded oil reservoirs to prevent them from entering easily. Applying grease to the threaded oil reservoirs during assembly can make the inner tube more lubricated. The inner tube can store grease, so the first and second anti-sway rings play a lubricating role every time the inner tube extends or retracts.

[0018] 3. The sliding teeth of the outer tube body are closely attached to the outer rings of the first anti-sway ring, piston oil seal, and second anti-sway ring. The first and second anti-sway rings of the front support seat machining parts do not have the draft angle of die casting, and are more compactly attached to the inner wall of the outer tube, resulting in better support and concentricity, and less swaying of the inner tube. Attached Figure Description

[0019] Figure 1 This is an exploded perspective view of the electric actuator of the present invention;

[0020] Figure 2 This is a three-dimensional structural diagram of the electric actuator of the present invention, omitting the outer tube body and the fixing frame;

[0021] Figure 3 yes Figure 2 The three-dimensional structural diagram omitting the inner tube and drive module is shown below.

[0022] Figure 4 yes Figure 3 A sectional view;

[0023] Figure 5 yes Figure 4 Enlarged view at point B;

[0024] Figure 6 This is a three-dimensional structural diagram of the sliding nut of the present invention;

[0025] Figure 7 This is a three-dimensional structural schematic diagram of the sliding nut of the present invention from another perspective;

[0026] Figure 8 This is a three-dimensional exploded three-dimensional structural diagram of the sliding nut of the present invention;

[0027] Figure 9 This is a three-dimensional structural diagram of the present invention after omitting the driving module;

[0028] Figure 10 yes Figure 9 Enlarged view at point A in the middle;

[0029] Figure 11 This is a three-dimensional enlarged view of the telescopic rod of the present invention after removing the outer tube body and the waterproof and dustproof module;

[0030] Figure 12 This is a three-dimensional enlarged view of the outer tube and the fixing frame of the present invention.

[0031] The following are the reference numerals: 1. Sliding sleeve; 11. Sliding groove; 12. Material removal hole; 13. Limiting part; 2. Sliding block; 21. Side groove; 22. Groove; 23. Limiting platform; 3. Screw sleeve; 31. Positioning screw; 4. Outer tube body; 41. Fixing bracket; 411. Hanging platform; 412. Positioning groove; 42. Micro switch; 43. Sliding tooth; 5. Lead screw; 51. Driven gear; 6. Inner tube; 7. Motor; 71. Drive gear; 8. Base; 9. Fixed end cover; 90. Single lip oil seal; 91. First anti-sway ring; 92. Second anti-sway ring; 92. Threaded oil reservoir; 920. Piston oil seal; 93. Sealing ring; 94. Sealing cover; 95. Detailed Implementation

[0032] Please see Figure 1-12 As shown, this invention relates to a waterproof and dustproof electric actuator, comprising a drive module, an outer tube assembly, an inner tube 6, a lead screw 5, and a sliding nut. The lead screw 5 and the inner tube 6 are both located within the outer tube assembly. The sliding nut is movably mounted on the lead screw 5. The drive module is drivenly connected to the lead screw 5. The inner tube 6 is sleeved on a limiting nut and extends outward from the outer tube assembly or retracts into the outer tube assembly along the length direction of the lead screw 5. A waterproof and dustproof module is engaged between the inner tube 6 and the outer tube assembly. This waterproof and dustproof module includes a single-lip oil seal 90, a first anti-sway ring 91, a piston oil seal 93, and a second anti-sway ring 92 arranged sequentially along the retraction direction of the inner tube 6. The inner rings of the single-lip oil seal 90, the first anti-sway ring 91, the piston oil seal 93, and the second anti-sway ring 92 are tightly fitted to the outer wall of the inner tube 6.

[0033] The drive module drives the lead screw 5 to rotate, and the lead screw 5 drives the entire sliding nut to slide back and forth in the outer tube, realizing the extension and retraction of the inner tube 6. At the same time, in this application, the waterproof and dustproof module includes a single-lip oil seal 90, a first anti-sway ring 91, a piston oil seal 93, and a second anti-sway ring 92 arranged in sequence along the retraction direction of the inner tube 6. The inner rings of the single-lip oil seal 90, the first anti-sway ring 91, the piston oil seal 93, and the second anti-sway ring 92 are in close contact with the outer wall of the inner tube 6. When the inner tube 6 retracts, because the inner rings of the single-lip oil seal 90, the first anti-sway ring 91, the piston oil seal 93, and the second anti-sway ring 92 are in close contact with the outer wall of the inner tube 6, the single-lip oil seal 90 plays a role in scraping off dirt (dust, mud, etc.) on the surface of the inner tube 6, and the internal piston oil seal 93 plays a role in waterproofing and dustproofing.

[0034] It should be noted that the single-lip oil seal 90 and piston oil seal 93 used in this application are products that can be purchased directly from the market, so their specific structures will not be discussed in detail.

[0035] Please see Figure 5 As shown, the inner walls of the first anti-sway ring 91 and the second anti-sway ring 92 are provided with several threaded oil storage grooves 920, and the threaded oil storage grooves 920 and the outer wall of the inner tube 6 form an oil storage cavity.

[0036] In addition, the inner walls of the first anti-sway ring 91 and the second anti-sway ring 92 are provided with several threaded oil reservoirs 920. Assuming the front single-lip oil seal 90, sand and dust need to move slowly upward through the threaded oil reservoirs 920 to prevent sand and dust from entering easily. Applying grease to the threaded oil reservoirs 920 during assembly can make the inner tube 6 more lubricated. The inner tube can store grease, so the first anti-sway ring 91 and the second anti-sway ring 92 play a lubricating role every time the inner tube 6 extends or retracts.

[0037] Furthermore, the outer tube assembly includes an outer tube body 4 and a fixed end cap 9, wherein the front end of the outer tube body 4 is provided with an opening, and the fixed end cap 9 covers the opening, and the center of the fixed end cap 9 is provided with an outlet for the inner tube 6 to pass through.

[0038] Please see Figure 12 As shown, further, the inner wall of the outer tube body 4 is provided with multiple sliding teeth 43 at intervals; the sliding nut includes a sliding assembly and a sliding sleeve 1. The inner wall of the sliding assembly is provided with an internal thread, one end of the sliding assembly is provided with an external thread, the sliding sleeve 1 is sleeved on the other end of the sliding assembly, and the outer wall of the sliding sleeve 1 is provided with multiple sliding grooves 11. Each sliding groove 11 is arranged along the axial direction of the sliding sleeve 1, and the multiple sliding teeth 43 of the outer tube are matched one-to-one with the multiple sliding grooves 11 of the sliding sleeve 1.

[0039] The outer tube body 4 is long and tubular. Multiple sliding teeth 43 are spaced out on the inner wall of the outer tube body 4. When the entire sliding nut slides in the outer tube, the multiple sliding teeth 43 of the outer tube body 4 correspond one-to-one with the multiple sliding grooves 11 of the sliding sleeve 1, so that the inner tube 6 slides more smoothly relative to the outer tube body 4.

[0040] Furthermore, an oil seal mounting groove is provided on the back of the fixed end cap 9 corresponding to the outlet position. A single-lip oil seal 90 is sealed and mounted within the oil seal mounting groove by a sealing ring 94, and a sealing cap 95 covers the surface of the oil seal mounting groove. In this specific embodiment, the sealing performance of the single-lip oil seal 90 within the oil seal mounting groove by the sealing ring 94 is further improved, and displacement of the single-lip oil seal 90 can be prevented. Therefore, a sealing cap 95 covers the surface of the oil seal mounting groove.

[0041] Furthermore, the sliding teeth 43 of the outer tube body 4 are closely attached to the outer rings of the first anti-sway ring 91, the piston oil seal 93, and the second anti-sway ring 92.

[0042] The sliding teeth 43 of the outer tube body 4 are closely attached to the outer rings of the first anti-sway ring 91, piston oil seal 93, and second anti-sway ring 92. The first anti-sway ring 91 and second anti-sway ring 92 of the front support seat machining parts do not have the die-casting draft angle, and are more compactly attached to the inner wall of the outer tube, with better support force and concentricity, and the inner tube 6 swings less.

[0043] Please see Figure 6-8 As shown, the sliding assembly further includes a slider 2 and a threaded sleeve 3. Both the slider 2 and the threaded sleeve 1 are annular. The internal thread is provided on the inner wall of the threaded sleeve 3. The slider 2 is sleeved on the outside of the threaded sleeve 3. The slider 2 and the threaded sleeve 3 are positioned by two positioning screws 31. The two positioning screws 31 are axially arranged between the slider 2 and the threaded sleeve 3. A part of the same positioning screw 31 is located on the inner wall groove of the slider 2, and the other part of the positioning screw 31 is located on the outer wall groove of the threaded sleeve 3. The two positioning screws 31 are located on the end faces of the slider 2 and the threaded sleeve 3 and are arranged opposite to each other.

[0044] The sliding assembly includes a slider 2 and a threaded sleeve 3. Both the slider 2 and the threaded sleeve 3 are annular. The internal thread is provided on the inner wall of the threaded sleeve 3. The slider 2 is sleeved on the outside of the threaded sleeve 3. In this embodiment, the outer wall of the threaded sleeve 3 and the inner wall of the slider 2 are connected by threads, so that the slider 2 and the threaded sleeve 3 move together. In order to prevent the threaded sleeve 3 from rotating relative to the slider 2, the slider 2 and the threaded sleeve 3 are positioned by two positioning screws 31. The two positioning screws 31 are axially provided between the slider 2 and the threaded sleeve 3. A part of the same positioning screw 31 is located on the inner wall groove of the slider 2, and the other part of the positioning screw 31 is located on the outer wall groove of the threaded sleeve 3. The two positioning screws 31 are located on the end faces of the slider 2 and the threaded sleeve 3 and are arranged opposite each other.

[0045] Furthermore, the external thread is located on the outer wall of the slider 2. The outer wall of the slider 2 away from its external thread is provided with multiple side grooves 21, multiple grooves 22 and an annular limiting platform 23. The multiple side grooves 21 are arranged along the axial direction of the slider 2, the multiple grooves 22 are arranged along the radial direction of the slider 2, the multiple side grooves 21 and the multiple grooves 22 are intersecting and communicating, and the limiting platform 23 is located between the multiple grooves 22 and the external thread.

[0046] Please see Figure 8 As shown, furthermore, the inner wall of the sliding sleeve 1 is rotatably limited to the outer wall of the slider 2. A limiting portion 13 extends outward from the outer wall of the sliding sleeve 1. Multiple material removal holes 12 are provided on the end face of the sliding sleeve 1. When the sliding sleeve 1 is fitted onto the slider 2, the external thread and the limiting platform 23 on the slider 2 are located outside the sliding sleeve 1.

[0047] Please see Figure 9-12 As shown, the inner wall of the outer tube body 4 is further provided with two hanging grooves and a positioning part. Multiple sliding teeth 43, two hanging grooves and positioning part are all arranged along the axial direction of the outer tube body 4. A fixed frame 41 is hung on the inner wall of the outer tube body 4 along its axial direction. The two ends of the fixed frame 41 are respectively provided with long strip-shaped hanging platforms 411. The two hanging platforms 411 are respectively matched with the two hanging grooves of the outer tube body 4. The end of the fixed frame 41 away from the outer tube body 4 is provided with a positioning groove 412. The positioning groove 412 is matched with the positioning part of the outer tube body 4. Micro switches 42 are fixed at both ends of the fixed frame 41. The sliding sleeve 1 is located between the two micro switches 42. The limiting part 13 of the sliding sleeve 1 is located on the side of the fixed frame 41.

[0048] The entire sliding nut can slide between two microswitches 42. When the limiting part 13 of the sliding sleeve 1 touches one of the microswitches 42, the internal circuit board will control the motor 7 to stop working. The position of the two microswitches 42 determines the upper and lower limits of the movement of the inner tube 6.

[0049] The lead screw 5 is threaded through the sleeve 3, that is, the outer wall of the lead screw 5 is threadedly connected to the sleeve 3. The inner tube 6 is sleeved on the external thread of the slider 2 near the nut and presses against its limiting platform 23 so that the inner tube 6 and the slider 2 are fixedly connected by threads.

[0050] In this specific embodiment, the drive module includes a motor 7, the output end of the motor 7 is provided with a drive gear 71, the lead screw 5 of the telescopic rod is provided with a driven gear 51, the drive gear 71 meshes with the driven gear 51 through multiple transmission gears, and the drive gear 71, transmission gears and driven gear 51 are all located in a base 8.

[0051] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A waterproof and dustproof electric linear actuator, characterized in that, The system includes a drive module, an outer tube assembly, an inner tube, a lead screw, and a sliding nut. The lead screw and the inner tube are both located inside the outer tube assembly. The sliding nut is movably mounted on the lead screw. The drive module is connected to the lead screw. The inner tube is sleeved on a limiting nut and extends out of the outer tube assembly or retracts into the outer tube assembly along the length of the lead screw. A waterproof and dustproof module is fitted between the inner tube and the outer tube assembly. This waterproof and dustproof module includes a single-lip oil seal, a first anti-sway ring, a piston oil seal, and a second anti-sway ring arranged sequentially along the retraction direction of the inner tube. The inner rings of the single-lip oil seal, the first anti-sway ring, the piston oil seal, and the second anti-sway ring are tightly fitted to the outer wall of the inner tube. The outer tube assembly includes an outer tube body and a fixed end cap. The front end of the outer tube body is provided with an opening, and the fixed end cap covers the opening. The center of the fixed end cap is provided with an outlet for the inner tube to pass through. The inner wall of the outer tube body is provided with multiple sliding teeth at intervals; the sliding nut includes a sliding assembly and a sliding sleeve. The inner wall of the sliding assembly is provided with an internal thread, one end of the sliding assembly is provided with an external thread, the sliding sleeve is sleeved on the other end of the sliding assembly, and the outer wall of the sliding sleeve is provided with multiple sliding grooves. Each sliding groove is arranged along the axial direction of the sliding sleeve, and the multiple sliding teeth of the outer tube and the multiple sliding grooves of the sliding sleeve are matched one by one. The sliding assembly includes a slider and a threaded sleeve, both of which are annular. The internal thread is provided on the inner wall of the threaded sleeve. The slider is sleeved on the outside of the threaded sleeve. The slider and the threaded sleeve are positioned by two positioning screws. The two positioning screws are axially located between the slider and the threaded sleeve. A part of the same positioning screw is located on the inner wall groove of the slider, and the other part of the positioning screw is located on the outer wall groove of the threaded sleeve. The two positioning screws are located on the end faces of the slider and the threaded sleeve and are arranged opposite to each other.

2. The waterproof and dustproof electric actuator according to claim 1, characterized in that: The inner walls of the first anti-sway ring and the second anti-sway ring are provided with several threaded oil storage grooves, and the threaded oil storage grooves and the outer wall of the inner tube form an oil storage cavity.

3. The waterproof and dustproof electric actuator according to claim 1, characterized in that: The back of the fixed end cap is provided with an oil seal mounting slot corresponding to the outlet position. The single-lip oil seal is sealed and mounted in the oil seal mounting slot by a sealing ring, and the surface of the oil seal mounting slot is covered with a sealing cap.

4. A waterproof and dustproof electric actuator according to claim 3, characterized in that: The sliding teeth of the outer tube body are in close contact with the outer rings of the first anti-sway ring, the piston oil seal, and the second anti-sway ring.

5. A waterproof and dustproof electric actuator according to claim 1, characterized in that: The external thread is located on the outer wall of the slider. The outer wall of the slider at the end away from the external thread is provided with multiple side grooves, multiple grooves and an annular limiting platform. The multiple side grooves are arranged along the axial direction of the slider, the multiple grooves are arranged along the radial direction of the slider, the multiple side grooves and the multiple grooves are intersecting and communicating, and the limiting platform is located between the multiple grooves and the external thread.

6. A waterproof and dustproof electric actuator according to claim 1, characterized in that: The inner wall of the sliding sleeve is rotated and limited to the outer wall of the slider. The outer wall of the sliding sleeve extends outward to a limiting part. Multiple material removal holes are provided on the end face of the sliding sleeve. When the sliding sleeve is fitted onto the slider, the external thread and the limiting platform on the slider are located outside the sliding sleeve.

7. A waterproof and dustproof electric actuator according to claim 1, characterized in that: The inner wall of the outer tube body is also provided with two hanging slots and a positioning part. Multiple sliding teeth, two hanging slots and positioning part are all arranged along the axial direction of the outer tube body. A fixed frame is hung on the inner wall of the outer tube body along its axial direction. The two ends of the fixed frame are respectively provided with long strip-shaped hanging platforms. The two hanging platforms are respectively matched with the two hanging slots of the outer tube body. The end of the fixed frame away from the outer tube body is provided with a positioning groove. The positioning groove is matched with the positioning part of the outer tube body. Micro switches are fixed at both ends of the fixed frame. The sliding sleeve is located between the two micro switches. The limiting part of the sliding sleeve is located on the side of the fixed frame.

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