CN111146041B - Driving mechanism of vacuum switch - Google Patents

Abstract

The invention discloses a driving mechanism of a vacuum switch, which comprises a first pure iron plate; a second pure iron plate; a bottom plate; a first support column; a second support; the brake separating coil is fixed on the lower surface of the first pure iron plate; the closing coil is fixed on the upper surface of the second pure iron plate; the vortex disc is arranged between the opening coil and the closing coil; the upper end of the transmission shaft extends out of the upper surface of the first pure iron plate; the fixed seat is fixed on the lower surface of the second pure iron plate; the guide section is sleeved in the guide hole; the limiting groove is arranged on the guide section and extends along the circumferential direction of the guide section; the first elastic piece is arranged in the mounting hole; the limiting ball is arranged in the mounting hole and positioned between the first elastic piece and the guide section; the lower end of the mounting piece is fixed with the upper surface of the bottom plate, and the upper end of the mounting piece extends upwards; the limiting piece is arranged on the mounting piece; the second elastic piece is arranged between the end face of the lower end of the transmission shaft and the limiting piece. The vacuum switch is driven to be opened and closed quickly, the time is short, and the reliability of opening and closing of the vacuum switch can be ensured.

Description

A driving mechanism for a vacuum switch

Technical Field

The invention relates to a switch driving device in a flexible direct current ultra-high voltage converter valve control power transmission system, and in particular to a driving mechanism for a vacuum switch.

Background technique

The flexible DC UHV converter valve control is a solid-state switch composed of power electronic devices. Since DC does not cross zero, it is impossible to use the existing AC vacuum circuit breaker for disconnection. At present, the flexible DC UHV converter valve transmission system uses an improved vacuum switch, which usually uses a magnetic drive mechanism to drive the vacuum switch to open or close. The magnetic drive mechanism includes an opening coil, a closing coil, an eddy current disk, and a connecting rod. The pulse magnetic field generated by the opening coil and the closing coil drives the eddy current disk to move up and down, driving the contact to close and disconnect, completing the opening and closing action. According to needs, in order to keep the solid-state switch in the open or closed state, a magnetic mechanism is used to maintain it. The excitation time is relatively long, resulting in a slow response speed when switching between the open and closed states. In addition, the magnetic mechanism requires a permanent magnet, and the product cost is relatively high.

Therefore, how to shorten the response time of solid-state switches and reduce product costs has become a technical problem that needs to be solved urgently.

Summary of the invention

The object of the present invention is to provide a driving mechanism for a vacuum switch, which can drive the vacuum switch to open and close with a fast speed and a short time, and can ensure the reliability of the vacuum switch opening and closing.

The technical solution of the present invention for achieving the above-mentioned object is as follows:

A driving mechanism for a vacuum switch, comprising:

The first pure iron plate;

The second pure iron plate;

Base plate;

a first support, the upper end of which is fixed to the lower surface of the first pure iron plate, and the lower end of which is fixed to the upper surface of the second pure iron plate;

a second support, the upper end of which is fixed to the lower surface of the second pure iron plate, and the lower end of which is fixed to the upper surface of the bottom plate;

A tripping coil, which is fixed to the lower surface of the first pure iron plate;

a closing coil, which is fixed to the upper surface of the second pure iron plate;

The eddy current disk is arranged between the opening coil and the closing coil and can move toward the opening coil or the closing coil;

The transmission shaft, the upper end of which passes through the second pure iron plate, the closing coil, the eddy current disk, the opening coil, the first pure iron plate in sequence and extends out of the upper surface of the first pure iron plate, the lower end of which is located between the second pure iron plate and the base, and is fixed to the eddy current disk, and is movably matched with the first pure iron plate, the opening coil, the closing coil, and the second pure iron plate and can reciprocate up and down along its own axis;

A fixing seat, which is fixed to the lower surface of the second pure iron plate, and includes a guide hole penetrating along the vertical direction thereof and a mounting hole arranged on the side thereof and extending toward the inner wall of the guide hole and penetrating the inner wall of the guide hole;

The guide section is formed by the portion of the transmission shaft between the lower surface of the second pure iron plate and the lower end surface of the transmission shaft, and is sleeved in the guide hole and can reciprocate up and down along the guide hole;

A limiting groove, which is arranged on the guide section and extends along the circumference of the guide section;

A first elastic member, which is disposed in the mounting hole;

A limiting ball, which is arranged in the mounting hole and located between the first elastic member and the guide section;

A mounting member, the lower end of which is fixed to the upper surface of the bottom plate, and the upper end of which extends upward and points to the lower end surface of the transmission shaft;

A limiting member, which is arranged on the mounting member;

The second elastic member is arranged between the lower end surface of the transmission shaft and the limiting member.

The distance between the closing coil and the opening coil is greater than the stroke of the eddy current disk.

The opening coil, eddy current disk and closing coil are all circular, and their centers are collinear.

The gap distance between the eddy current disk and the closing coil is 1 mm, and the gap distance between the eddy current disk and the opening coil is 1 mm.

It also includes a first guide sleeve which is sleeved in the inner ring of the opening coil and passes through the first pure iron plate, the transmission shaft is sleeved in the first guide sleeve and slidably cooperates with the first guide sleeve, and the first guide sleeve is fixedly connected to the inner ring of the opening coil and the first pure iron plate; it also includes a second guide sleeve which is sleeved in the inner ring of the closing coil and passes through the second pure iron plate, the transmission shaft is sleeved in the second guide sleeve and slidably cooperates with the second guide sleeve, and the second guide sleeve is fixedly connected to the inner ring of the closing coil and the second pure iron plate.

The first elastic member is a compression spring, and the second elastic member is a top spring sleeved outside the mounting member.

The outer periphery of the end of the guide section facing the base is provided with a boss.

The mounting piece has an external thread, the limiting piece has a through hole, the inner wall of the through hole has an internal thread, and the mounting piece and the limiting piece are screwed together; or, the mounting piece and the limiting piece are made in one piece, and the lower end of the mounting piece is screwed together with a nut fixed to the upper surface of the base plate.

It also includes an adjusting piece, which is screwed into the mounting hole through an opening of the mounting hole located on the side of the fixing seat.

The beneficial effects of the present invention are:

When the present invention is applied to a vacuum switch in a flexible DC ultra-high voltage power transmission system, the upper end of the transmission shaft is connected to the moving contact of the vacuum switch. The present invention generates a magnetic field by energizing the opening/closing coil, which generates a repulsive force with the eddy current disk, drives the transmission shaft to move up and down, drives the moving contact in the vacuum switch to move upward and contact with the static contact to achieve closing, or drives the moving contact in the vacuum switch to move downward and separate from the static contact to achieve opening, thereby achieving the opening and closing of the vacuum switch. The up and down moving direction of the transmission shaft of the present invention is coaxial with the moving contact movement direction, and there is no crank lever. The mechanical transfer function of the driving system is simple and stable, and the action time dispersion is less than plus or minus 0.2ms, which is suitable for precise control. An external energy storage capacitor is used to discharge the closing and opening coils. The driving force strength is proportional to the capacitor energy storage. The capacitor energy storage method can output a large current so that the circuit breaker can complete closing and opening within 2ms. The moving and static contacts have fast closing and opening speeds, small movement inertia, high closing and opening efficiency, reduced closing and opening time, high control accuracy, short pre-breakdown time, short arc existence time, small switch on-state loss, low heat generation, small electrical wear on the surface of the moving and static contacts, and extended service life.

When the present invention is in the open state, the self-locking mechanism composed of the fixed seat, the guide section, the limit groove, the first elastic member, the limit ball, the mounting member, the limit member, and the second elastic member locks the transmission shaft, which can ensure that the present invention can reliably maintain the open state. When closing the switch, the self-locking mechanism extends the second elastic member to support the lower end surface of the transmission shaft, which can ensure that the moving contact and the static contact of the present invention can reliably maintain contact, prevent the moving contact from malfunctioning, and ensure the reliability of opening and closing. The self-locking mechanism of the present invention has a simple structure and reliable and stable performance. It flexibly applies the principle of mechanics to achieve the functions of opening self-locking and closing retention. It also replaces the traditional magnetic retention, reduces the excitation time, speeds up the opening and closing response speed, and reduces the cost of permanent magnets.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of the present invention.

FIG2 is a schematic diagram of the connection structure between the opening coil, the closing coil, the eddy current disk, and the transmission shaft of the present invention.

3 is a schematic diagram of the connection structure among the fixing seat, the guide section, the limiting groove, the limiting ball, the mounting member, and the second elastic member of the present invention.

FIG. 4 is an enlarged view of FIG. 1A .

FIG. 5 is a schematic structural diagram of a fixing base of the present invention.

Detailed ways

The examples given below are specific descriptions of the present invention. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention.

It should be noted that, in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. The descriptions involving "first", "second" and the like in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Fig. 1-2 exemplarily shows an embodiment of a driving mechanism of a vacuum switch in many embodiments of the present invention. The driving mechanism of the vacuum switch includes a first pure iron plate 1, a second pure iron plate 2, a bottom plate 3, a first support 4, a second support 5, an opening coil 6, a closing coil 7, an eddy current disc 8, a transmission shaft 9, a fixing seat 10, a first elastic member 11, a guide section 91, a limiting groove 92, a limiting ball 12, a mounting member 13, a limiting member 14, and a second elastic member 15.

In the embodiment shown in Fig. 1, the first pure iron plate 1, the second pure iron plate 2, and the bottom plate 3 are all flat plate structures. It can be understood that the first pure iron plate 1, the second pure iron plate 2, and the bottom plate 3 are not limited to flat plate structures, but can also be other structures as long as they can achieve their functions in the present invention.

The upper end of the first support 4 is fixed to the lower surface of the first pure iron plate 1, and the lower end thereof is fixed to the upper surface of the second pure iron plate 2, for example, by welding. The upper end of the second support 5 is fixed to the lower surface of the second pure iron plate 2, and the lower end thereof is fixed to the upper surface of the bottom plate 3, for example, by welding. Alternatively, the first pure iron plate 1, the second pure iron plate 2, the bottom plate 3, the first support 4, and the second support 5 are integrally formed.

In the embodiment presented in FIG1 , the number of the first pillars 4 and the second pillars 5 are both 4, and they are respectively distributed in a quadrilateral. It can be understood that the number of the first pillars 4 and the second pillars 5 is not a specific value, and can be other numbers according to actual needs. When the present invention is arranged in the manner presented in FIG1 , the first pillars 4 and the second pillars 5 both play a supporting role.

Referring to FIG. 2 , the opening coil 6 is fixed to the lower surface of the first pure iron plate 1 . The closing coil 7 is fixed to the upper surface of the second pure iron plate 2 . The eddy current disc 8 is arranged between the opening coil 6 and the closing coil 7 and can move toward the opening coil 6 or the closing coil 7 . The upper end of the transmission shaft 9 passes through the second pure iron plate 2 , the closing coil 7 , the eddy current disc 8 , the opening coil 6 , the first pure iron plate 1 in sequence and extends out of the first pure iron plate 1 , and its lower end is located between the second pure iron plate 2 and the base, and is fixed to the eddy current disc 8 , and is movably matched with the first pure iron plate 1 , the opening coil 6 , the closing coil 7 , and the second pure iron plate 2 and can reciprocate up and down along its own axis. Preferably, the upper end of the transmission shaft 9 is connected to a connecting seat 20 , and the connecting seat 20 is used to connect to the moving contact of the vacuum switch. The outer diameter of the connecting seat 20 is larger than the inner diameter of the through hole provided in the first pure iron plate 1 for the transmission shaft 9 to pass through, so as to prevent the travel of the transmission shaft 9 moving downward from exceeding the allowable range. The transmission shaft 9 may be a cylindrical stepped shaft.

The opening coil 6 includes a first coil frame 61 and a first enameled wire 62 disposed on the first coil frame 61 . The closing coil 7 includes a second coil frame 71 and a second enameled wire 72 disposed on the second coil frame 71 .

3-5, the fixing seat 10 is fixed to the lower surface of the second pure iron plate 2, and includes a guide hole 101 penetrating along the vertical direction thereof and a mounting hole 102 arranged on the side thereof and extending toward the inner wall of the guide hole 101 and penetrating the inner wall of the guide hole 101. The guide hole 101 guides the transmission shaft 9 to move up and down, and can prevent the lower end of the transmission shaft 9 from swinging sideways when the transmission shaft 9 moves up and down.

The guide section 91 is formed by the portion of the transmission shaft 9 between the lower surface of the second pure iron plate 2 and the lower end surface of the transmission shaft 9 , and is sleeved in the guide hole 101 and can reciprocate up and down along the guide hole 101 .

The limiting groove 92 is provided in the guide section 91 and extends circumferentially along the guide section 91. It is preferred that the limiting groove 92 extends circumferentially along the guide section 91 and is connected end to end.

The first elastic member 11 is disposed in the mounting hole 102 .

The limiting ball 12 is a spherical structure, which is disposed in the mounting hole 102 and located between the first elastic member 11 and the guide section 91. The limiting ball 12 can be, but is not limited to, a steel ball.

The lower end of the mounting member 13 is fixed to the upper surface of the base plate 3, and the upper end thereof extends upward and points to the lower end surface of the transmission shaft 9. The mounting member 13 can also prevent the travel of the transmission shaft 9 from moving downward beyond the allowable range.

The limiting member 14 is disposed on the mounting member 13 .

The second elastic member 15 is disposed between the lower end surface of the transmission shaft 9 and the limiting member 14 , and the limiting member 14 limits the second elastic member 15 from moving downward.

It is preferred that the up and down moving trajectory of the transmission shaft 9 coincides with its axis, so as to reliably ensure that the up and down moving direction of the transmission shaft 9 is coaxial with the moving direction of the moving contact of the vacuum switch without a crank arm lever.

In some embodiments, the distance between the closing coil 7 and the opening coil 6 is greater than the stroke of the eddy current disk 8 .

In some embodiments, the opening coil 6 , the eddy current disk 8 and the closing coil 7 are all circular, and their centers are collinear.

In some embodiments, the gap distance between the eddy current disk 8 and the closing coil 7 is 1 mm, and the gap distance between the eddy current disk 8 and the opening coil 6 is 1 mm.

In some embodiments, the present invention further includes a first guide sleeve 27 which is sleeved in the inner ring of the opening coil 6 and passes through the first pure iron plate 1, the transmission shaft 9 is sleeved in the first guide sleeve 27 and slidably cooperates with the first guide sleeve 27, and the first guide sleeve 27 is fixedly connected to the inner ring of the opening coil 6 and the first pure iron plate 1, so as to facilitate the flexible movement of the transmission shaft 9 in the first guide sleeve 27 and prevent the transmission shaft 9 from swinging sideways when moving up and down. It also includes a second guide sleeve 28 which is sleeved in the inner ring of the closing coil 7 and passes through the second pure iron plate 2, the transmission shaft 9 is sleeved in the second guide sleeve 28 and slidably cooperates with the second guide sleeve 28, and the second guide sleeve 28 is fixedly connected to the inner ring of the closing coil 7 and the second pure iron plate 2, so as to facilitate the flexible movement of the transmission shaft 9 in the second guide sleeve 28 and prevent the transmission shaft 9 from swinging sideways when moving up and down.

In some embodiments, the first elastic member 11 is a compression spring, and the second elastic member 15 is a top spring sleeved outside the mounting member 13 .

In some embodiments, the outer periphery of the end of the guide section 91 facing the base has a boss 93, which limits the upward movement of the transmission shaft 9 to prevent the second elastic member 15 from being positioned too far upward and causing damage to the moving contact and/or static contact of the vacuum switch.

In some embodiments, the mounting member 13 and the limiting member 14 are made in one piece, and the lower end of the mounting member 13 is screwed with a nut 18 fixed to the upper surface of the bottom plate 3. By rotating the mounting member 13, the torque of the second elastic member 15 can be easily adjusted. By adjusting the mounting member 13, the height of the upper end surface of the mounting member 13 relative to the upper surface of the bottom plate 3 can be adjusted, and the travel of the transmission shaft 9 moving downward can also be limited. Alternatively, the mounting member 13 has an external thread, the limiting member 14 has a through hole, and the inner wall of the through hole has an internal thread. The mounting member 13 is screwed with the limiting member 14, and the torque of the second elastic member 15 can be easily adjusted by rotating the limiting member 14.

In some embodiments, the present invention also includes an adjusting member 19, which is screwed into the mounting hole 102 from an opening of the mounting hole 102 located on the side of the fixing seat 10. Rotating the adjusting member 19 can adjust the torque of the first elastic member 11, thereby adjusting the pressure of the limiting ball 12 on the limiting groove 92, and further adjusting the self-locking force.

When the present invention is applied to a vacuum switch in a flexible DC ultra-high voltage power transmission system, the upper end of the transmission shaft 9 is connected to the moving contact of the vacuum switch. When the switch is opened, the opening coil 6 generates a magnetic field driven by an external energy storage capacitor, and a repulsive force is generated between the opening coil 6 and the eddy current disk 8, driving the eddy current disk 8 to move downward. The eddy current disk 8 applies a downward force to the transmission shaft 9, and this force overcomes the upward force applied to the transmission shaft 9 by the second elastic member 15, thereby driving the transmission shaft 9 to move downward, and the transmission shaft 9 drives the moving contact to move downward, and the moving contact is separated from the static contact of the vacuum switch to achieve opening. The limiting ball 12 is pressed on the side of the transmission shaft 9 under the elastic force of the first elastic member 11, and the limiting ball 12 and the side of the transmission shaft 9 together form a rolling pair. In the process of the eddy current disk 8 driving the transmission shaft 9 to move downward, under the action of friction, the transmission shaft 9 moves downward and drives the limiting ball 12 to rotate in the mounting hole 102. As the transmission shaft 9 continues to move downward, the limiting groove 92 and the mounting hole 102 on the inner wall of the guide hole 101 gradually align with each other. During this process, the limiting ball 12 gradually moves from the side wall of the transmission shaft 9 to the limiting groove 52 under the elastic force of the first elastic member 11, until the limiting ball 12 partially enters the limiting groove 92 and can no longer move toward the bottom surface of the limiting groove 92. At this time, part of the limiting ball 12 is located in the limiting groove 92, and the rest of the limiting ball 12 is located in the mounting hole 102. The limiting ball 12, the limiting groove 92, and the mounting hole 102 cooperate with each other to lock the transmission shaft 9 so that it cannot move freely up and down, thereby ensuring that the vacuum switch can reliably maintain the open state and realizing the self-locking function of the vacuum switch.

When closing the circuit breaker, the closing coil 7 generates a magnetic field driven by an external energy storage capacitor, and generates a repulsive force between the closing coil 7 and the eddy current disk 8, driving the eddy current disk 8 to move upward. Under the combined action of the eddy current disk 8 exerting an upward force on the transmission shaft 9 and the second elastic member 15 exerting an upward force on the transmission shaft 9, the transmission shaft 9 moves upward, and the transmission shaft 9 drives the moving contact to move upward, and the moving contact contacts the static contact of the vacuum switch to achieve closing. When the transmission shaft 9 just starts to move upward, the limiting ball 12 is subjected to the force of the edge of the side wall of the limiting groove 92, and one of the components of the force is directed to the first elastic member 11. The component overcomes the force of the first elastic member 11 on the limiting ball 12, and pushes the limiting ball 12 to move along the mounting hole 102 away from the transmission shaft 9. As the transmission shaft 9 continues to move upward, the limiting ball 12 gradually moves along the mounting hole 102 away from the transmission shaft 9, and the first elastic member 11 is gradually compressed until the limiting ball 12 completely leaves the limiting groove 92 and releases the self-locking. The transmission shaft 9 continues to move upward, and the limiting ball 12 is pressed against the side of the transmission shaft 9 under the elastic force of the first elastic member 11. The limiting ball 12 and the side of the transmission shaft 9 together form a rolling pair. During the process of the eddy current disk 8 driving the transmission shaft 9 to move upward, under the action of friction, the transmission shaft 9 moves upward to drive the limiting ball 12 to rotate in the mounting hole 102. After the transmission shaft 9 moves upward into position, the second elastic member 15 stretches upward to support the transmission shaft 9, ensuring that the vacuum switch can reliably maintain the closed state, realizing the closed-holding function of the vacuum switch. The second elastic member 15 can also play a buffering role when the transmission shaft 9 moves downward.

It should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

The present invention has been described in detail above with reference to the embodiments, which are illustrative rather than restrictive. Changes and modifications without departing from the overall concept of the present invention are within the protection scope of the present invention.

Claims (8)

1. A driving mechanism of a vacuum switch, which is used in a flexible DC ultra-high voltage power transmission system, characterized in that it comprises: First pure iron plate (1); Second pure iron plate (2); Bottom plate (3); A first support (4), the upper end of which is fixed to the lower surface of the first pure iron plate (1), and the lower end of which is fixed to the upper surface of the second pure iron plate (2); A second support (5), the upper end of which is fixed to the lower surface of the second pure iron plate (2), and the lower end of which is fixed to the upper surface of the bottom plate (3); A tripping coil (6) fixed to the lower surface of the first pure iron plate (1); A closing coil (7) fixed to the upper surface of the second pure iron plate (2); An eddy current disk (8) is arranged between the opening coil (6) and the closing coil (7) and is capable of moving toward the opening coil (6) or the closing coil (7); A transmission shaft (9), the upper end of which passes through the second pure iron plate (2), the closing coil (7), the eddy current disk (8), the opening coil (6), and the first pure iron plate (1) in sequence and extends out of the upper surface of the first pure iron plate (1); the lower end of which is located between the second pure iron plate (2) and the base, and is fixed to the eddy current disk (8); and it is movably matched with the first pure iron plate (1), the opening coil (6), the closing coil (7), and the second pure iron plate (2) and can reciprocate up and down along its own axis; A fixing seat (10) fixed to the lower surface of the second pure iron plate (2), comprising a guide hole (101) penetrating in the vertical direction thereof and a mounting hole (102) arranged on the side thereof and extending in the direction of the inner wall of the guide hole (101) and penetrating the inner wall of the guide hole (101); A guide section (91), which is formed by a portion of the transmission shaft (9) located between the lower surface of the second pure iron plate (2) and the lower end surface of the transmission shaft (9), and is sleeved in the guide hole (101) and can reciprocate up and down along the guide hole (101); A limiting groove (92) is provided on the guide section (91) and extends circumferentially along the guide section (91); A first elastic member (11) disposed in the mounting hole (102); A limiting ball (12) disposed in the mounting hole (102) and located between the first elastic member (11) and the guide section (91); A mounting member (13), the lower end of which is fixed to the upper surface of the bottom plate (3), and the upper end of which extends upward and points to the lower end surface of the transmission shaft (9); A limiting member (14) disposed on the mounting member (13); A second elastic member (15) disposed between the lower end surface of the transmission shaft (9) and the limiting member (14); The distance between the closing coil (7) and the opening coil (6) is greater than the stroke of the eddy current disk (8); The gap distance between the eddy current disk (8) and the closing coil (7) is 1 mm, and the gap distance between the eddy current disk (8) and the opening coil (6) is 1 mm. 2. The drive mechanism according to claim 1, characterized in that the opening coil (6), the eddy current disk (8) and the closing coil (7) are all circular, and their centers are collinear. 3. The drive mechanism according to claim 1 is characterized in that it also includes a first guide sleeve (16) sleeved in the inner ring of the opening coil (6) and passing through the first pure iron plate (1), the transmission shaft (9) is sleeved in the first guide sleeve (16) and slidably cooperates with the first guide sleeve (16), and the first guide sleeve (16) is fixedly connected to the inner ring of the opening coil (6) and the first pure iron plate (1); and also includes a second guide sleeve (17) sleeved in the inner ring of the closing coil (7) and passing through the second pure iron plate (2), the transmission shaft (9) is sleeved in the second guide sleeve (17) and slidably cooperates with the second guide sleeve (17), and the second guide sleeve (17) is fixedly connected to the inner ring of the closing coil (7) and the second pure iron plate (2). 4. The driving mechanism according to claim 1, characterized in that the first elastic member (11) is a compression spring, and the second elastic member (15) is a top spring sleeved outside the mounting member (13). 5. The driving mechanism according to claim 1, characterized in that the outer periphery of the end of the guide section (91) facing the base has a boss (93). 6. The driving mechanism according to claim 1 is characterized in that the mounting member (13) has an external thread, the limiting member (14) has a through hole, the inner wall of the through hole has an internal thread, and the mounting member (13) and the limiting member (14) are screwed together; or, the mounting member (13) and the limiting member (14) are made as one piece, and the lower end of the mounting member (13) is screwed together with a nut (18) fixed to the upper surface of the base plate (3). 7. The driving mechanism according to claim 1, characterized in that the upper end of the transmission shaft (9) is connected to a connecting seat (20), and the outer diameter of the connecting seat (20) is larger than the inner diameter of a through hole provided in the first pure iron plate (1) for the transmission shaft (9) to pass through. 8. The driving mechanism according to any one of claims 1 to 7, characterized in that it further comprises an adjusting member (19), wherein the adjusting member (19) is screwed into the mounting hole (102) from an opening of the mounting hole (102) located on the side of the fixing seat (10).