Low-noise shaded pole motor

Abstract

The invention discloses a low-noise shaded pole motor, and belongs to the technical field of motors, the low-noise shaded pole motor comprises a rotor part, a stator part and a coil part, the stator part is provided with a first limiting frame and a second limiting frame, the first limiting frame and the second limiting frame are fixedly connected with the stator part through a bearing bolt assembly, and a rotating shaft is rotatably connected with the first limiting frame through a bearing. One end of the rotor part is rotationally connected with the second limiting frame through a rotary joint, a push-type abutting assembly is installed on the first limiting frame, one end of the push-type abutting assembly is connected with the rotor part and used for abutting and limiting the rotor part, and an annular centering positioning piece and a rotary driving assembly are further installed on the first limiting frame; the annular centering positioning piece is connected with the rotary driving assembly; according to the invention, the problem that the rotor part stretches out and draws back during high-speed rotation and the problem that the rotor part collides with the stator part are avoided, the overall stability and durability of the motor are effectively enhanced, and the noise in the operation process is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and particularly to a low-noise shaded-pole motor. Background Art

[0002] A shaded-pole motor is a type of single-phase AC motor, usually adopting a cage-type skewed-slot cast-aluminum rotor. According to the different shapes of the stator, it is divided into a salient-pole shaded-pole motor and a non-salient-pole shaded-pole motor. The characteristic of a shaded-pole motor is that part of the magnetic pole of the rotor is covered by a shaded cover, causing the rotor magnetic field to rotate. This kind of motor has the advantages of simple structure, easy manufacturing, reliable operation, convenient maintenance, etc. At the same time, its speed is precisely synchronized with the power frequency applied to the motor, and it is usually applicable to low-torque applications such as small household appliances, such as fans and air circulators.

[0003] However, when the existing shaded-pole motor is in use, due to wear, the distance between the bearing and the washer will increase, causing the rotor and the rotating shaft to move back and forth during operation, generating abnormal noises. At the same time, the wear of the bearing is likely to cause the rotor to sink, easily resulting in collisions between the rotor and the stator, with relatively large noises, and there are certain drawbacks in the use process.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] Therefore, the present invention provides a low-noise shaded-pole motor to solve the above problems.

[0006] The present invention provides the following technical solution: A low-noise shaded-pole motor, including a rotor part, a stator part, and a coil part. The coil part is fixed on the stator part, and a short-circuit ring is fixedly installed on the coil part. The rotor part is rotatably inserted on the stator part, and a rotating shaft is fixedly installed on the rotor part. It is characterized in that: a first limiting frame and a second limiting frame are installed on the stator part. The first limiting frame and the second limiting frame are fixedly connected to the stator part through the supporting pin assembly. The rotating shaft is rotatably connected to the first limiting frame through the bearing. One end of the rotor part is rotatably connected to the second limiting frame through the rotary joint. A pushing type pressing component is installed on the first limiting frame. One end of the pushing type pressing component is connected to the rotor part for pressing and limiting the rotor part. A ring-shaped centering positioning part and a rotary driving component are also installed on the first limiting frame. The ring-shaped centering positioning part is connected to the rotary driving component, and the ring-shaped centering positioning part rolls and fits on the outer wall of the smooth ring installed on the rotor part.

[0007] As a preferred solution of the present invention, in order to enable the bidirectional screw to rotate in the limit chute through the rotating joint by controlling the first screwing head, the supporting pin assembly includes the first connecting head, the second connecting head and the mounting strip. The first connecting head and the second connecting head are respectively fixed on the first limit frame and the second limit frame. The mounting strip is fixed on the stator part. A limit chute is provided on the mounting strip, and the bidirectional screw is installed in the limit chute. One end of the bidirectional screw is rotatably connected to the inner wall of one end of the limit chute through the rotating joint, and the other end of the bidirectional screw is fixedly installed with the first screwing head.

[0008] As a preferred solution of the present invention, in order to enable the two gathering sliders to slide synchronously in opposite directions in the limit chute by controlling the rotation of the bidirectional screw, so that the positioning pin can be driven by the first U-shaped frame and the second U-shaped frame to be inserted into the first connecting head and the second connecting head. The gathering sliders are threadedly installed on the bidirectional screw. The gathering sliders are slidably clamped in the limit chute, and the number of the gathering sliders is two. The two gathering sliders are respectively located at the reverse thread ends of the bidirectional screw. The first U-shaped frame and the second U-shaped frame are respectively fixedly installed on the two gathering sliders. The positioning pins are fixedly installed on the inner walls of one ends of the first U-shaped frame and the second U-shaped frame. One end of the positioning pin is inserted into the first connecting head and the second connecting head.

[0009] As a preferred solution of the present invention, in order to enable the push screw to rotate on the fixed mounting base through the rotating stud by controlling the second screwing head, so as to drive the threaded slider to move. The push-type pressing assembly includes the fixed mounting base and the connecting ring. The fixed mounting base is fixed on the first limit frame. The push screw is installed on the fixed mounting base. One end of the push screw is rotatably connected to the fixed mounting base through the rotating stud, and the other end of the push screw is fixedly installed with the second screwing head. The threaded slider is installed on the push screw.

[0010] As a preferred solution of the present invention, in order to enable the threaded slider to drive the smooth ball to advance forward through the push rod. The push rod is fixedly installed on the threaded slider. The push rod is slidably inserted into the fixed mounting base. One end of the push rod is fixedly installed with the smooth ball. The connecting ring is fixed on the rotor part. The smooth ball is slidably clamped in the smooth circular ring groove opened on the connecting ring.

[0011] As a preferred embodiment of the present invention, in order to enable the square connection block to move relative to the annular mounting block through the correction slide bar, the annular centering member includes the arc connection head, the arc connection head is fixed on the first limiting frame, the annular mounting block is fixedly installed on the arc connection head, the annular mounting block is located outside the smooth ring, the correction slide bar is slidably inserted into the annular mounting block, the correction slide bars are evenly distributed in a circumferential manner, one end of the correction slide bar is fixedly installed with the square connection block, and the square connection block is elastically connected to the inner wall of the annular mounting block through the return spring.

[0012] As a preferred embodiment of the present invention, in order to be able to extrude the smooth ring through the smooth roller while avoiding affecting the rotation of the smooth ring, the square connection block is fixedly installed with the ramp connection block, the smooth roller is rotatably installed on the ramp connection block, and the smooth roller is in rolling contact with the outer wall of the smooth ring.

[0013] As a preferred embodiment of the present invention, in order to enable the rotation drive ring to rotate or be fixed by controlling the extension connection block, so that the smooth extrusion rod can perform a circular motion or positioning, and realize the extrusion of the ramp connection block, the rotation drive assembly includes the rotation drive ring, the rotation drive ring is rotatably installed on the first limiting frame through the arc-shaped slider, the extension connection block is fixedly installed on the arc-shaped slider, the extension connection block is fixed on the first limiting frame through the positioning screw, the smooth extrusion rod is fixedly installed on the rotation drive ring, and the smooth extrusion rod is in fitting connection with the inclined side wall of the ramp connection block.

[0014] The beneficial effects of the present invention are as follows: 1. Through the push-type tightening assembly, the problem of expansion and contraction of the rotor part during high-speed rotation is avoided, effectively enhancing the overall stability and durability of the motor, and significantly reducing the noise during operation; 2. Through the coordinated work of the annular centering member and the rotation drive assembly, not only the precise centering of the rotor part is realized, avoiding the collision between the rotor part and the stator part, but also the friction loss is greatly reduced through rolling contact, further achieving the effect of noise reduction. Brief Description of the Drawings

[0015] The present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 is the overall structural schematic diagram of the present invention; Figure 2 is the installation structural schematic diagram of the connection ring of the present invention; Figure 3It is a schematic diagram of the installation structure of the bidirectional screw of the present invention; Figure 4 It is a schematic diagram of the installation structure of the positioning pin rod of the present invention; Figure 5 It is a schematic diagram of the structure of the push-type tightening assembly of the present invention; Figure 6 It is a schematic diagram of the connection structure of the annular centering positioning member and the rotary drive assembly of the present invention.

[0017] Figure 7 It is a schematic diagram of the structure of the annular centering positioning member of the present invention.

[0018] Figure 8 It is a schematic diagram of the structure of the rotary drive assembly of the present invention.

[0019] Legend description: 1. Rotor part; 2. Stator part; 3. Coil part; 4. Short-circuit ring; 5. Rotating shaft; 6. First limiting frame; 7. Second limiting frame; 8. Supporting plug assembly; 801. First connecting head; 802. Second connecting head; 803. Installation strip block; 804. Bidirectional screw; 805. Rotating joint; 806. First screwing head; 807. Gathering slider; 808. First U-shaped frame; 809. Second U-shaped frame; 810. Positioning pin rod; 9. Bearing; 10. Rotary joint; 11. Push-type tightening assembly; 1101. Fixed mounting seat; 1102. Connecting ring; 1103. Push screw; 1104. Rotating stud; 1105. Second screwing head; 1106. Threaded slider; 1107. Push slide bar; 1108. Smooth ball; 12. Annular centering positioning member; 1201. Arc-shaped connecting head; 1202. Annular mounting block; 1203. Correction slide bar; 1204. Square connecting block; 1205. Return spring; 1206. Slope-shaped connecting block; 1207. Smooth roller; 13. Rotary drive assembly; 1301. Rotary drive ring; 1302. Arc-shaped slider; 1303. Extension connecting block; 1304. Positioning screw; 1305. Smooth extrusion rod; 14. Smooth ring. Detailed implementation manners

[0020] 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 the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] The following gives specific embodiments.

[0022] As Figures 1-8As shown in the figure, a low-noise shaded-pole motor includes a rotor part 1, a stator part 2, and a coil part 3. The coil part 3 is fixed on the stator part 2, and a short-circuit ring 4 is fixedly installed on the coil part 3. The rotor part 1 is rotatably inserted into the stator part 2, and a rotating shaft 5 is fixedly installed on the rotor part 1. It is characterized in that: a first limit frame 6 and a second limit frame 7 are installed on the stator part 2. The first limit frame 6 and the second limit frame 7 are fixedly connected to the stator part 2 through a supporting pin assembly 8. The rotating shaft 5 is rotatably connected to the first limit frame 6 through a bearing 9. One end of the rotor part 1 is rotatably connected to the second limit frame 7 through a rotary joint 10. A push-type tightening assembly 11 is installed on the first limit frame 6. One end of the push-type tightening assembly 11 is connected to the rotor part 1 for tightly limiting the rotor part 1. An annular centering positioning member 12 and a rotation driving assembly 13 are also installed on the first limit frame 6. The annular centering positioning member 12 is connected to the rotation driving assembly 13, and the annular centering positioning member 12 rolls and fits on the outer wall of a smooth ring 14 installed on the rotor part 1. When in use, ensure that the motor is correctly installed and powered on. After the motor starts, the rotor part 1 starts to rotate in the stator part 2. The first limit frame 6 and the second limit frame 7 are firmly connected to the stator part 2 through the supporting pin assembly 8, providing a stable support structure for the rotation of the rotor part 1 and improving the convenience of disassembly and assembly. The rotating shaft 5 is connected to the first limit frame 6 through a precision bearing 9 to ensure a smooth rotation process with low noise. One end of the rotor part 1 is connected to the second limit frame 7 through a rotary joint 10 to achieve flexible rotational connection. The push-type tightening assembly 11 functions on the first limit frame 6, and one end of it is tightly connected to the rotor part 1, effectively preventing the rotor part 1 and the rotating shaft 5 from expanding and contracting during high-speed rotation, enhancing the stability and durability of the motor and greatly reducing the generation of noise. At the same time, the annular centering positioning member 12 and the rotation driving assembly 13 work together. The annular centering positioning member 12 tightly fits on the outer wall of the smooth ring 14 of the rotor part 1, not only ensuring the centering positioning of the rotor part 1 but also reducing the friction loss through rolling contact, further reducing the noise. The rotation driving assembly 13 provides the necessary power to effectively control the annular centering positioning member 12.

[0023] The supporting plug component 8 includes a first connector 801, a second connector 802 and a mounting bar block 803. The first connector 801 and the second connector 802 are respectively fixed on the first limiting frame 6 and the second limiting frame 7. The mounting bar block 803 is fixed on the stator part 2. A limiting sliding groove is formed in the mounting bar block 803. A bidirectional screw rod 804 is installed in the limiting sliding groove. One end of the bidirectional screw rod 804 is rotatably connected to the inner wall of one end of the limiting sliding groove through a rotating joint 805. A first screwing head 806 is fixedly installed at the other end of the bidirectional screw rod 804. A gathering slider 807 is threadedly installed on the bidirectional screw rod 804. The gathering slider 807 is slidably clamped in the limiting sliding groove, and the number of the gathering sliders 807 is two. The two gathering sliders 807 are respectively located at the reverse thread ends of the bidirectional screw rod 804. A first U-shaped frame 808 and a second U-shaped frame 809 are respectively fixedly installed on the two gathering sliders 807. A positioning pin rod 810 is fixedly installed on the inner wall of one end of the first U-shaped frame 808 and the second U-shaped frame 809. One end of the positioning pin rod 810 is inserted into the first connector 801 and the second connector 802. During use, the first connector 801 and the second connector 802 are respectively firmly fixed on the first limiting frame 6 and the second limiting frame 7. Then, the mounting bar block 803 is accurately fixed at a predetermined position of the stator part 2, ensuring that both ends of the mounting bar block 803 are aligned with the first connector 801 and the second connector 802. The bidirectional screw rod 804 is driven to rotate in the limiting sliding groove by rotating the first screwing head 806. With the rotation of the bidirectional screw rod 804, the two gathering sliders 807 approach each other due to the action of the reverse threads and slide along the limiting sliding groove until they reach the required positions. The first U-shaped frame 808 and the second U-shaped frame 809 respectively installed on the two gathering sliders 807 also move accordingly until the positioning pin rods 810 thereon are accurately inserted into the reserved holes of the first connector 801 and the second connector 802, realizing a firm connection. This not only simplifies the installation process but also ensures the firmness and stability of the connection between the limiting frame and the stator part 2, providing a solid foundation for the smooth operation of the motor.

[0024] The pushing and clamping assembly 11 includes a fixed mounting base 1101 and a connecting ring 1102. The fixed mounting base 1101 is fixedly mounted on the first limiting frame 6. A pushing lead screw 1103 is mounted on the fixed mounting base 1101. One end of the pushing lead screw 1103 is rotatably connected to the fixed mounting base 1101 through a rotating stud head 1104. A second screwing head 1105 is fixedly mounted at the other end of the pushing lead screw 1103. A threaded slider 1106 is mounted on the pushing lead screw 1103. A pushing slide rod 1107 is fixedly mounted on the threaded slider 1106. The pushing slide rod 1107 is slidably inserted into the fixed mounting base 1101. A smooth ball 1108 is fixedly mounted at one end of the pushing slide rod 1107. The connecting ring 1102 is fixed on the rotor part 1. The smooth ball 1108 is slidably clamped in a smooth circular ring 14 groove opened on the connecting ring 1102. When in use, first ensure that the fixed mounting base 1101 has been firmly mounted on the first limiting frame 6. Then, drive the pushing lead screw 1103 to rotate in the fixed mounting base 1101 by rotating the second screwing head 1105. As the pushing lead screw 1103 rotates, the threaded slider 1106 moves along the thread track of the lead screw, driving the pushing slide rod 1107 to slide smoothly under the guidance of the fixed mounting base 1101. The smooth ball 1108 fixedly mounted at one end of the pushing slide rod 1107 moves accordingly until it closely abuts and is slidably clamped in the smooth circular ring 14 groove opened on the connecting ring 1102 of the rotor part 1. By continuously rotating the second screwing head 1105, the position of the smooth ball 1108 in the circular ring groove can be adjusted, so as to apply an appropriate clamping force to the rotor part 1, ensuring its stability and accuracy during rotation, preventing the rotor part 1 and the rotating shaft 5 from telescoping and moving, and being able to flexibly adjust the clamping force according to needs, providing a strong guarantee for the smooth and low-noise operation of the motor.

[0025] The annular centering positioning member 12 includes an arc-shaped connecting head 1201, the arc-shaped connecting head 1201 is fixed on the first limiting frame 6, an annular mounting block 1202 is fixedly installed on the arc-shaped connecting head 1201, the annular mounting block 1202 is located outside the smooth ring 14, a correction sliding rod 1203 is slidably inserted on the annular mounting block 1202, the correction sliding rods 1203 are evenly distributed in a circumferential manner, a square connecting block 1204 is fixedly installed at one end of the correction sliding rod 1203, the square connecting block 1204 is elastically connected with the inner wall of the annular mounting block 1202 through a return spring 1205, a ramp-shaped connecting block 1206 is fixedly installed on the square connecting block 1204, a smooth roller 1207 is rotatably installed on the ramp-shaped connecting block 1206, the smooth roller 1207 is in rolling contact with the outer wall of the smooth ring 14. During use, ensure that the arc-shaped connecting head 1201 has been firmly fixed on the first limiting frame 6, and the annular mounting block 1202 is thereby positioned outside the smooth ring 14. The correction sliding rods 1203 evenly distributed in a circumferential manner on the annular mounting block 1202 are elastically connected with the square connecting block 1204 through the return spring 1205, so that the smooth roller 1207 on the ramp-shaped connecting block 1206 can closely fit on the outer wall of the smooth ring 14. When the motor is started and the rotor part 1 drives the smooth ring 14 to rotate, the smooth roller 1207 rolls on the outer wall of the ring accordingly, ensuring that the rotor part 1 always maintains a centered position. If the rotor part 1 has a slight deviation during the rotation process, the return spring 1205 will push the ramp-shaped connecting block 1206 and the smooth roller 1207 to make fine adjustments through the square connecting block 1204 and the correction sliding rod 1203, quickly correcting the rotor part 1 back to the central position, improving the positioning accuracy of the rotor part 1, and also reducing the friction loss and noise through rolling contact, further enhancing the operating efficiency and stability of the motor.

[0026] The rotation drive assembly 13 includes a rotation drive ring 1301. The rotation drive ring 1301 is rotatably mounted on the first limit frame 6 through an arc-shaped slider 1302. An extended connection block 1303 is fixedly mounted on the arc-shaped slider 1302. The extended connection block 1303 is fixed to the first limit frame 6 through a positioning screw 1304. A smooth extrusion rod 1305 is fixedly mounted on the rotation drive ring 1301. The smooth extrusion rod 1305 is in fit connection with the inclined side wall of the ramp-shaped connection block 1206. During use, ensure that the rotation drive ring 1301 is rotatably and flexibly mounted on the first limit frame 6 through the arc-shaped slider 1302. The extended connection block 1303 on the arc-shaped slider 1302 is firmly fixed to the first limit frame 6 through the positioning screw 1304, providing stable support for the rotation drive ring 1301. As the smooth extrusion rod 1305 moves along the inclined side wall of the ramp-shaped connection block 1206, it will push the ramp-shaped connection block 1206 forward, causing the smooth roller 1207 to push the smooth ring 14, realizing the centering correction of the smooth ring 14, enabling the rotor part 1 to be kept in the centered position, avoiding the collision between the rotor part 1 and the stator part 2 during rotation due to the skew of the rotor part 1 and generating noise, and improving the stability of the motor during use.

[0027] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and all these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-noise shaded-pole motor, comprising a rotor part (1), a stator part (2) and a coil part (3), the coil part (3) is fixed on the stator part (2), a short-circuit ring (4) is fixedly installed on the coil part (3), the rotor part (1) is rotatably inserted on the stator part (2), and a rotating shaft (5) is fixedly installed on the rotor part (1), characterized in that: A first limiting frame (6) and a second limiting frame (7) are mounted on the stator part (2). The first limiting frame (6) and the second limiting frame (7) are fixedly connected to the stator part (2) through a supporting pin assembly (8). The rotating shaft (5) is rotatably connected to the first limiting frame (6) through a bearing (9). One end of the rotor part (1) is rotatably connected to the second limiting frame (7) through a rotary joint (10). A pushing type tightening assembly (11) is mounted on the first limiting frame (6). One end of the pushing type tightening assembly (11) is connected to the rotor part (1) for tightly limiting the rotor part (1). An annular centering positioning member (12) and a rotary driving assembly (13) are further mounted on the first limiting frame (6). The annular centering positioning member (12) is connected to the rotary driving assembly (13), and the annular centering positioning member (12) is in rolling contact with the outer wall of a smooth ring (14) mounted on the rotor part (1).

2. The shaded-pole motor with low noise according to claim 1, wherein: The supporting pin assembly (8) includes a first connecting head (801), a second connecting head (802) and a mounting strip block (803). The first connecting head (801) and the second connecting head (802) are respectively fixed on the first limiting frame (6) and the second limiting frame (7). The mounting strip block (803) is fixed on the stator part (2). A limiting sliding groove is formed in the mounting strip block (803). A bidirectional screw rod (804) is mounted in the limiting sliding groove. One end of the bidirectional screw rod (804) is rotatably connected to the inner wall of one end of the limiting sliding groove through a rotating joint (805). A first screwing head (806) is fixedly mounted at the other end of the bidirectional screw rod (804).

3. The shaded-pole motor with low noise according to claim 2, wherein: Two gathering sliders (807) are threadedly mounted on the bidirectional screw rod (804). The gathering sliders (807) are slidably clamped in the limiting sliding groove, and the number of the gathering sliders (807) is two. The two gathering sliders (807) are respectively located at the reverse thread ends of the bidirectional screw rod (804). A first U-shaped frame (808) and a second U-shaped frame (809) are respectively fixedly mounted on the two gathering sliders (807). Positioning pin rods (810) are fixedly mounted on the inner walls of one ends of the first U-shaped frame (808) and the second U-shaped frame (809). One ends of the positioning pin rods (810) are inserted into the first connecting head (801) and the second connecting head (802).

4. The shaded-pole motor with low noise according to claim 1, wherein: The pushing type tightening assembly (11) includes a fixed mounting seat (1101) and a connecting ring (1102). The fixed mounting seat (1101) is fixed on the first limiting frame (6). A pushing lead screw (1103) is mounted on the fixed mounting seat (1101). One end of the pushing lead screw (1103) is rotatably connected to the fixed mounting seat (1101) through a rotating stud head (1104). A second screwing head (1105) is fixedly mounted at the other end of the pushing lead screw (1103). A threaded slider (1106) is mounted on the pushing lead screw (1103).

5. The shaded-pole motor with low noise according to claim 4, wherein: A propulsion slide rod (1107) is fixedly installed on the threaded slider (1106). The propulsion slide rod (1107) is slidably inserted into the fixedly installed seat (1101). A smooth ball (1108) is fixedly installed at one end of the propulsion slide rod (1107). The connecting ring (1102) is fixed on the rotor part (1). The smooth ball (1108) is slidably clamped in the smooth circular ring (14) groove formed on the connecting ring (1102).

6. The shaded-pole motor with low noise according to claim 1, wherein: The annular centering member (12) includes an arc-shaped connecting head (1201). The arc-shaped connecting head (1201) is fixed on the first limiting frame (6). An annular mounting block (1202) is fixedly installed on the arc-shaped connecting head (1201). The annular mounting block (1202) is located outside the smooth circular ring (14). A correction slide rod (1203) is slidably inserted into the annular mounting block (1202). The correction slide rods (1203) are evenly distributed in a circular pattern. A square connecting block (1204) is fixedly installed at one end of the correction slide rod (1203). The square connecting block (1204) is elastically connected to the inner wall of the annular mounting block (1202) through a return spring (1205).

7. The shaded-pole motor with low noise according to claim 6, wherein: A ramp-shaped connecting block (1206) is fixedly installed on the square connecting block (1204). A smooth roller (1207) is rotatably installed on the ramp-shaped connecting block (1206). The smooth roller (1207) is in rolling contact with the outer wall of the smooth circular ring (14).

8. The shaded-pole motor with low noise according to claim 7, wherein: The rotary drive assembly (13) includes a rotary drive ring (1301). The rotary drive ring (1301) is rotatably installed on the first limiting frame (6) through an arc-shaped slider (1302). An extension connecting block (1303) is fixedly installed on the arc-shaped slider (1302). The extension connecting block (1303) is fixed on the first limiting frame (6) through a positioning screw (1304). A smooth extrusion rod (1305) is fixedly installed on the rotary drive ring (1301). The smooth extrusion rod (1305) is in fit connection with the inclined side wall of the ramp-shaped connecting block (1206).

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