CN114927386A

CN114927386A - Direct current contactor electromagnetic driving mechanism capable of fast responding

Info

Publication number: CN114927386A
Application number: CN202210653514.1A
Authority: CN
Inventors: 顾春朋; 张昆; 蔡一飞; 陈建华; 李康
Original assignee: Kunshan Guoli Yuantong New Energy Technology Co ltd
Current assignee: Kunshan Guoli Yuantong New Energy Technology Co ltd
Priority date: 2022-06-09
Filing date: 2022-06-09
Publication date: 2022-08-19

Abstract

The invention discloses a direct current contactor electromagnetic driving mechanism capable of quickly responding, which comprises: the coil is fixedly connected with the rotor, the permanent magnet is further installed in the inner cavity of the yoke, and when the coil is powered on, each conducting wire of the coil is subjected to ampere force in a magnetic field formed by the permanent magnet, so that the coil drives the rotor to move perpendicular to the current direction of the rotor. The direct current contactor electromagnetic driving mechanism capable of fast responding is characterized in that the coil is fixedly connected with the rotor, the yoke is provided with the permanent magnet, the coil is acted by ampere force in a magnetic field generated by the permanent magnet after being electrified, so that the coil drives the rotor to move, the action response time can be reduced to the level of several ms, the purpose of fast response is achieved, the response speed identical to that of an electronic switch can be achieved, the electromagnetic driving mechanism is compact in structure, and the action response mode is simple and controllable.

Description

Direct current contactor electromagnetic driving mechanism capable of fast responding

Technical Field

The invention relates to the technical field of direct current contactors, in particular to a direct current contactor electromagnetic driving mechanism capable of quickly responding.

Background

The direct current contactor is an electromagnetic switch for controlling the on-off of a large current through the on-off of a small current, and is mainly used in the fields of electric automobiles, charging piles, photovoltaics, energy storage and the like.

The existing direct current contactor is driven in a mechanical switch mode, coils in the contactor are all static and fixed, and only a movable iron core and a pushing mechanism move. The movement mode is that the coil is electrified to generate a magnetic field, the movable iron core is magnetized and magnetic attraction force is generated, so that the movable iron core drives the pushing mechanism to move, and finally the movable contact is in contact with the fixed contact to be conducted. After the coil is electrified, a magnetic loop is firstly generated around the coil to magnetize the movable iron core and the magnetic conduction plate, and then attraction force can be generated between the movable iron core and the magnetic conduction plate to make the movable iron core act, and the action response time of the process is dozens of ms, so that the action response of the direct current contactor switch is slow, and the action response is not fast due to electronic switching.

Disclosure of Invention

The invention aims to provide a direct current contactor electromagnetic driving mechanism capable of responding quickly, so as to overcome the defect that the existing direct current contactor has slow switching action response.

The technical scheme adopted by the invention for solving the technical problem is as follows: a fast response dc contactor electromagnetic drive mechanism comprising: the coil and the rotor are arranged in the inner cavity of the yoke, the coil is fixedly connected with the rotor, the permanent magnet is further arranged in the inner cavity of the yoke, and when the coil is electrified, each conducting wire of the coil is subjected to ampere force in a magnetic field formed by the permanent magnet, so that the coil drives the rotor to move in a direction perpendicular to the current direction of the rotor.

As a further improvement of the present invention, the mover is magnetized by a magnetic field generated when the coil is energized to displace, and the displacement direction of the mover is the same as the movement direction in which the coil is energized to receive an ampere force.

As a further improvement of the present invention, the magnetic coil assembly further includes a magnetic conductive plate fixed at the top opening end of the yoke, and when the coil is energized, a magnetic loop can be formed among the yoke, the magnetic conductive plate and the mover to drive the mover to move upward and attract the mover to the magnetic conductive plate.

As a further improvement of the present invention, an iron core is disposed in an inner cavity of the yoke along an axis thereof, the mover is slidably sleeved on the iron core, and the coil is wound on an outer side of the mover.

As a further improvement of the invention, two permanent magnets are arranged, are fixed on the inner side wall of the yoke and are symmetrically distributed on two sides of the coil;

the polarity of one side surface of each permanent magnet, which faces the coil, is N-pole, and the polarity of the other side surface of each permanent magnet is S-pole; or the polarities of one side surface of the two permanent magnets facing the coil are S poles, and the polarities of the other side surface of each permanent magnet are N poles.

As a further improvement of the invention, two permanent magnets are arranged and symmetrically embedded on the side wall of the yoke and arranged close to the bottom wall;

the polarities of the upper ends of the two permanent magnets are N poles, and the polarities of the lower ends of the two permanent magnets are S poles; or the polarities of the upper ends of the two permanent magnets are S poles, and the polarities of the lower ends of the two permanent magnets are N poles.

As a further improvement of the invention, two permanent magnets are arranged, are horizontally embedded on the bottom wall of the yoke iron and are symmetrically distributed on two sides of the iron core;

the polarities of the ends, close to each other, of the two permanent magnets are both N poles, and the polarities of the ends, far away from each other, of the two permanent magnets are both S poles; or the polarities of the ends, close to each other, of the two permanent magnets are S poles, and the polarities of the ends, far away from each other, of the two permanent magnets are N poles.

As a further improvement of the invention, the permanent magnet is annular, is sleeved on the iron core and is positioned below the rotor;

the polarity of the upper end of the permanent magnet is an N pole, and the polarity of the lower end of the permanent magnet is an S pole; or the polarity of the upper end of the permanent magnet is S pole, and the polarity of the lower end of the permanent magnet is N pole.

As a further improvement of the present invention, an iron core is disposed in an inner cavity of the yoke along an axis thereof, the permanent magnet is annular, the permanent magnet is fixedly sleeved on the iron core, the coil is wound on an outer side of the permanent magnet and can slide up and down relative to the permanent magnet, and the mover is fixed on a top of the coil;

the polarity of the peripheral surface of the permanent magnet is an N pole, and the polarity of the inner peripheral surface of the permanent magnet is an S pole; or the polarity of the peripheral surface of the permanent magnet is S pole, and the polarity of the inner peripheral surface of the permanent magnet is N pole.

The beneficial effects of the invention are: the invention provides a direct current contactor electromagnetic driving mechanism capable of fast responding, wherein a coil is fixedly connected with a rotor, a permanent magnet is arranged on a yoke, the coil is acted by ampere force in a magnetic field generated by the permanent magnet after being electrified, so that the coil drives the rotor to move, the action response time can be reduced to the level of several ms, the purpose of fast responding is achieved, the response speed same as that of an electronic switch can be achieved, the advantages of a mechanical switch can be kept, the electromagnetic driving mechanism is compact in structure, and the action response mode is simple and controllable.

Drawings

Fig. 1 is a schematic cross-sectional view of a first embodiment of an electromagnetic driving mechanism of a dc contactor according to the present invention;

FIG. 2 is a schematic cross-sectional view of a second embodiment of the electromagnetic driving mechanism of the quick response DC contactor according to the present invention;

FIG. 3 is a schematic cross-sectional view of a third embodiment of an electromagnetic driving mechanism of a fast response DC contactor according to the present invention;

FIG. 4 is a schematic cross-sectional view of a fourth embodiment of the electromagnetic driving mechanism of the quick response DC contactor according to the present invention;

fig. 5 is a schematic cross-sectional view of an embodiment of a dc contactor electromagnetic driving mechanism according to the invention;

fig. 6 is a schematic cross-sectional view of a sixth embodiment of the electromagnetic driving mechanism of the dc contactor according to the present invention;

fig. 7 is a schematic cross-sectional view of a seventh embodiment of an electromagnetic driving mechanism of a dc contactor according to the present invention.

In fig. 1, the directions of arrows shown by the yoke, the mover and the magnetic conductive plate are directions of magnetic loops generated when the coil is energized; in fig. 2, the directions of arrows shown along the yoke and the magnetic conductive plate are the directions of magnetic loops generated when the coil is energized; the directions of arrows shown in the permanent magnets in fig. 1 and 2 are the directions of magnetic fields generated by the permanent magnets; the directions of arrows shown in fig. 3 to 7 are all the directions of magnetic fields generated by the permanent magnets; the labeled "N" in fig. 1 to 7 indicates that the polarity of the corresponding end of the permanent magnet is N-pole, and the labeled "S" indicates that the polarity of the corresponding end of the permanent magnet is S-pole.

The following description is made with reference to the accompanying drawings:

1. a yoke iron; 101. an iron core; 2. a coil; 3. a mover; 4. a permanent magnet; 5. a magnetic conduction plate.

Detailed Description

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Example one

Referring to fig. 1, the present invention provides a dc contactor electromagnetic driving mechanism capable of fast response, including: yoke 1, coil 2, active cell 3, at least one permanent magnet 4 and magnetic conduction board 5. The yoke 1 is cup-shaped, not limited to a square or circular configuration, and has a bottom wall and a peripheral wall integrally connected around the bottom wall, the top of the yoke 1 being an open end, and an inner cavity formed inside thereof. The coil 2 and the rotor 3 are both arranged in the inner cavity of the yoke 1.

Further, the yoke 1 extends upwards from the inner bottom wall along the axis of the yoke in the inner cavity to form an iron core 101, the mover 3 is slidably sleeved on the iron core 101, and the coil 2 is wound on the outer side of the mover 3. The coil 2 is fixedly connected with the mover 3, and the coil 2 may be directly fixed on the outer periphery of the mover 3 or indirectly fixed on the outer side of the mover 3 through parts such as a coil frame and the like, so that the coil 2 and the mover 3 can synchronously move up and down in the inner cavity of the yoke 1.

It should be noted that the shape and material of the mover 3 in this embodiment are not limited, but a cylindrical shape with a hole at the center is preferable for facilitating assembly with the coil 2. The material can be mild steel or industrial pure iron, so that the material has the characteristics of easy magnetization and quick demagnetization.

The magnetic conductive plate 5 is an iron sheet, the fixing cover is arranged at the top opening end of the yoke 1, a certain gap is left between the top end of the iron core 101 and the magnetic conductive plate 5, and a magnetic loop (see an arrow marked along the yoke 1 and the magnetic conductive plate 5 in fig. 1) can be formed between the yoke 1 and the iron core 101 thereof, and the mover 3 and the magnetic conductive plate 5 by a magnetic field generated when the coil 2 is electrified, so that the mover 3 is magnetized to generate displacement, and moves upwards to be attracted to the magnetic conductive plate 5. The permanent magnet 4 is also installed in the inner cavity of the yoke 1, and the magnetic field formed by the permanent magnet 4 around the coil 2 can make each wire of the coil 2 subject to an ampere force when the coil 2 is electrified, so that the coil 2 drives the rotor 3 to move perpendicular to the current direction, in other words, to move upwards perpendicular to the cross section of the coil 2.

The shape of the permanent magnet 4 is not limited to a bar shape, a tile shape, a ring shape, or the like, and the material thereof may be neodymium iron boron or ferrite.

As a preferred embodiment, the yoke 1 has a square cup shape, and the permanent magnet 4 is provided in two, each having a bar shape. The two permanent magnets 4 are respectively fixed on the left and right inner side walls of the yoke 1 and symmetrically distributed on two sides of the coil 2. The fixing mode of the two permanent magnets 4 and the inner side wall of the yoke 1 is not limited, and the two permanent magnets can be fixed by gluing preferably.

In the present embodiment, according to the winding direction of the coil 2, referring to fig. 1, the current flow direction after the coil 2 is energized is defined as the right side flowing in the direction perpendicular to the paper surface and the left side flowing out in the direction perpendicular to the paper surface. In a suitable manner, the polarities of the two permanent magnets 4 facing one side of the coil 2 are both set to be N-pole, the polarities of the other side of each permanent magnet are both set to be S-pole, and the directions of the generated magnetic fields are as shown in fig. 1 along the directions of the arrows marked by the two permanent magnets 4.

When the coil 2 is energized, a current flows through each wire of the coil 2 (or each coil of the coil 2), according to the left-hand rule, each wire of the coil 2 is acted by an ampere force in the magnetic field generated by the two permanent magnets 4, and after the ampere force is resolved, the direction of the total ampere force applied to the coil 2 is vertically upward, so that the upward movement perpendicular to the cross section of the coil 2 is generated. Meanwhile, after the coil 2 is electrified, a magnetic field is generated, a magnetic loop is formed among the yoke 1, the rotor 3 and the magnetic conduction plate 5 are magnetized, opposite magnetic poles are attracted between the rotor 3 and the magnetic conduction plate 5, the rotor 3 is driven to move upwards and is attracted to the magnetic conduction plate 5, and then the rotor 3 pushes the moving contact to be in contact with the fixed contact through the push rod transmission assembly, so that the direct current contactor is closed. Therefore, it can be seen that this application is through with coil 2 and active cell 3 looks fixed connection, coil 2 receives the effect of ampere force and the magnetic attraction that active cell 3 received in the magnetic field that permanent magnet 4 produced after the circular telegram superposes mutually, impel active cell 3 to move, action response time can reduce to several ms rank, reach the purpose of quick response, can accomplish the response speed the same with electronic switch, can remain mechanical switch's advantage simultaneously again, and this electromagnetic drive mechanism compact structure, the action response mode is simply controllable.

Similarly, when the winding direction of the coil 2 is opposite, in other words, when the coil 2 is energized, the current flow direction is defined as the left side flowing in the direction perpendicular to the paper surface and the right side flowing out in the direction perpendicular to the paper surface, at this time, the magnetic poles of the two permanent magnets 4 should be correspondingly placed in opposite directions, that is, the polarities of one side surface of the two permanent magnets 4 facing the coil 2 are both S poles, and the polarities of the other side surface of each permanent magnet 4 are both N poles.

As another preferred embodiment of the present application, when the yoke 1 is a circular cup with an open top, the preferred permanent magnet 4 can be two tile-shaped or an integral ring structure, which can achieve the above technical effects.

Example two

Referring to fig. 2, the difference between the present embodiment and the first embodiment is: the top end of the iron core 101 in the yoke 1 extends upward close to the magnetic conductive plate 5. Thus, when the coil 2 is energized, a closed magnetic circuit is formed in the yoke 1, the core 101 thereof, and the magnetic conductive plate 5, and the mover 3 is magnetically short-circuited, so that the mover 3 is not magnetized. Therefore, only by means of the action of ampere force when the coil 2 is electrified, the mover 3 is driven to move upwards synchronously, and the purpose of quick response can be achieved by the structural mode.

The following examples respectively illustrate the preferred placement positions of several permanent magnets in the present application.

EXAMPLE III

The difference between this embodiment and the first or second embodiment is: the structure of yoke 1 and the position of putting and the magnetic pole direction of permanent magnet 4 are different, and two permanent magnets 4 symmetry are inlayed and are established on the lateral wall of yoke 1 and are close to the diapire setting.

Specifically, referring to fig. 3, the left and right side walls of the yoke 1 are both provided with mounting grooves with a size matching that of the permanent magnets 4 at positions close to the bottom wall, and the two permanent magnets 4 are respectively fixed in the two mounting grooves and fixed by gluing. The upper end of the circumferential wall of the yoke 1 positioned in the mounting groove is provided with a right-angle wall, the upper end of the permanent magnet 4 abuts against the right-angle wall, and the lower end of the permanent magnet 4 abuts against the bottom wall of the yoke 1.

In the present embodiment, referring to fig. 3, the current flow direction after the coil 2 is energized is defined as the right side flowing in the direction perpendicular to the paper surface and the left side flowing out in the direction perpendicular to the paper surface. The polarities of the upper ends of the two permanent magnets 4 are set to be N poles, the polarities of the lower ends of the two permanent magnets are set to be S poles, and the directions of the magnetic fields formed by the two permanent magnets 4 on the two sides of the iron core 101 are as indicated by arrows in fig. 3, so that the coil 2 is upward under the total ampere force when being electrified, and the mover 3 is driven to move upward, thereby achieving the same technical effect as the embodiment.

Similarly, when the current direction of the coil 2 is opposite, the polarities of the upper ends of the two permanent magnets 4 are set to be S poles, and the polarities of the lower ends of the two permanent magnets are set to be N poles.

Example four

The present embodiment is different from the third embodiment in that: the two permanent magnets 4 are fixed to the yoke 1 in a different manner.

Specifically, referring to fig. 4, mounting grooves matched with the permanent magnet 4 in size are formed between the left and right side walls of the yoke 1 and the bottom wall, the lower ends of the mounting grooves extend to the bottom wall of the yoke 1 and are provided with positioning grooves, a right-angle wall is formed at the upper end of the mounting groove on the peripheral wall of the yoke 1, the upper end of the permanent magnet 4 abuts against the right-angle wall, and the lower end of the permanent magnet 4 abuts against the positioning grooves on the bottom wall, so that the permanent magnet 4 is embedded and fixed. Compared with the third embodiment, the fixing mode of the permanent magnet 4 does not need gluing and other fixing modes, the assembling process is simple, and the structure is more compact.

EXAMPLE five

Referring to fig. 5, the difference between the present embodiment and the first or second embodiment is: the two permanent magnets 4 are horizontally embedded on the bottom wall of the yoke 1 and below the coil 2. Specifically, two mounting holes matched with the two permanent magnets 4 in size are symmetrically formed in the two sides, located on the iron core 101, of the bottom wall of the yoke 1, and the two permanent magnets 4 are respectively embedded in the two mounting holes in a gluing or interference fit mode.

In the present embodiment, referring to fig. 5, the current flow direction after the coil 2 is energized is defined as the right side flowing in the direction perpendicular to the paper surface and the left side flowing out in the direction perpendicular to the paper surface. With it looks adaptation, all set up the polarity of the one end that two permanent magnets 4 are close to each other to the N utmost point, all set up the polarity of the one end that keeps away from each other to the S utmost point, the magnetic field direction that two permanent magnets 4 formed in the both sides of iron core 101 is as the arrow point direction in fig. 5 for receive total ampere force direction upwards when coil 2 circular telegram, drive active cell 3 upward movement, can reach the same technological effect with the embodiment.

Similarly, when the current direction of the coil 2 is opposite, the polarities of the ends close to each other of the two permanent magnets 4 are set to be S-poles and the polarities of the ends far away from each other are set to be N-poles, which is not described in detail in this embodiment.

EXAMPLE six

Referring to fig. 6, the difference between the present embodiment and the first or second embodiment is: the permanent magnet 4 is in an integrated ring shape, is sleeved on the iron core 101, is positioned below the rotor 3, and is fixedly connected with the bottom wall of the yoke 1.

In the present embodiment, referring to fig. 6, the current flow direction after the coil 2 is energized is defined as the right side flowing in the direction perpendicular to the paper surface and the left side flowing out in the direction perpendicular to the paper surface. The upper ends of the permanent magnets 4 are arranged to be N-poles in a matched manner, the lower ends of the permanent magnets are arranged to be S-poles in a matched manner, and the directions of magnetic fields formed by the two permanent magnets 4 on the two sides of the iron core 101 are as the directions indicated by arrows in fig. 6, so that the coil 2 is upwards subjected to the total ampere force when being electrified, and the mover 3 is driven to upwards move, and the technical effect similar to that of the embodiment can be achieved.

Similarly, when the current direction of the coil 2 is opposite, the polarity of the upper end of the permanent magnet 4 is set to be the S pole, and the polarity of the lower end of the permanent magnet is set to be the N pole, which is not described in detail in this embodiment.

EXAMPLE seven

Referring to fig. 7, the difference between the present embodiment and the first or second embodiment is: the permanent magnet 4 is in an integrated ring shape and fixedly sleeved on the iron core 101. The coil 2 is wound on the outer side of the permanent magnet 4 and can slide up and down relative to the permanent magnet 4, and the rotor 3 is fixed on the top of the coil 2.

In the present embodiment, referring to fig. 7, the current flow direction after the coil 2 is energized is defined as the right side flowing in the direction perpendicular to the paper surface and the left side flowing out in the direction perpendicular to the paper surface. The polarity of the outer circumferential surface of the permanent magnet 4 is set to be N, the polarity of the inner circumferential surface is set to be S, and the direction of the generated magnetic field is as shown in fig. 7 along the direction of the arrow marked on the outer circumferential surface of the permanent magnet 4, so that the coil 2 is upward under the total ampere force when being electrified, and the mover 3 is driven to move upward, thereby achieving the same technical effect as the embodiment.

Similarly, when the current direction of the coil 2 is opposite, the polarity of the outer peripheral surface of the permanent magnet 4 is set to be S-pole, and the polarity of the inner peripheral surface thereof is set to be N-pole, which is not described in detail in this embodiment.

In the above description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The foregoing description is that of the preferred embodiment of the invention only, and the invention can be practiced in many ways other than as described herein, so that the invention is not limited to the specific implementations disclosed above. And that those skilled in the art may, using the methods and techniques disclosed above, make numerous possible variations and modifications to the disclosed embodiments, or modify equivalents thereof, without departing from the scope of the claimed embodiments. Any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. The utility model provides a but quick response's direct current contactor electromagnetic drive mechanism, includes yoke (1) and installs in coil (2) and active cell (3) in yoke (1) inner chamber, its characterized in that: the coil (2) is fixedly connected with the rotor (3), the permanent magnet (4) is further installed in the inner cavity of the yoke (1), when the coil (2) is electrified, each conducting wire of the coil is subjected to ampere force action in a magnetic field formed by the permanent magnet (4), and therefore the coil (2) drives the rotor (3) to move perpendicular to the current direction of the rotor.

2. The dc contactor electromagnetic drive mechanism of claim 1, wherein: the mover (3) can be magnetized and displaced under the action of a magnetic field generated when the coil (2) is electrified, and the displacement direction of the mover (3) is the same as the movement direction of the coil (2) subjected to the action of ampere force when the coil is electrified.

3. The direct current contactor electromagnetic drive mechanism capable of fast response according to claim 2, characterized in that: still include magnetic conductive plate (5), fix the open-top end department of yoke (1), coil (2) can be in when circular telegram yoke (1) magnetic conductive plate (5) and form magnetic circuit between active cell (3), order about active cell (3) rebound actuation is in on the magnetic conductive plate (5).

4. The direct current contactor electromagnetic drive mechanism capable of fast response according to claim 1, characterized in that: an iron core (101) is arranged in an inner cavity of the yoke (1) along the axis of the yoke, the rotor (3) can be slidably sleeved on the iron core (101), and the coil (2) is wound on the outer side of the rotor (3).

5. The dc contactor electromagnetic drive mechanism of claim 4, wherein: the two permanent magnets (4) are fixed on the inner side wall of the yoke (1) and symmetrically distributed on two sides of the coil (2);

the polarities of one side surface of each permanent magnet (4) facing the coil (2) are N poles, and the polarities of the other side surface of each permanent magnet are S poles; or the polarities of one side surface of the two permanent magnets (4) facing the coil (2) are S poles, and the polarities of the other side surface of each permanent magnet are N poles.

6. The dc contactor electromagnetic drive mechanism of claim 4, wherein: the two permanent magnets (4) are symmetrically embedded on the side wall of the yoke (1) and are arranged close to the bottom wall;

the polarities of the upper ends of the two permanent magnets (4) are N poles, and the polarities of the lower ends of the two permanent magnets are S poles; or the polarities of the upper ends of the two permanent magnets (4) are S poles, and the polarities of the lower ends of the two permanent magnets are N poles.

7. The direct current contactor electromagnetic drive mechanism capable of fast response according to claim 4, wherein: the two permanent magnets (4) are horizontally embedded on the bottom wall of the yoke (1) and symmetrically distributed on two sides of the iron core (101);

the polarities of the ends, close to each other, of the two permanent magnets (4) are both N poles, and the polarities of the ends, far away from each other, of the two permanent magnets are both S poles; or the polarities of the ends, close to each other, of the two permanent magnets (4) are S poles, and the polarities of the ends, far away from each other, of the two permanent magnets are N poles.

8. The direct current contactor electromagnetic drive mechanism capable of fast response according to claim 4, wherein: the permanent magnet (4) is annular, is sleeved on the iron core (101), and is positioned below the rotor (3);

the polarity of the upper end of the permanent magnet (4) is an N pole, and the polarity of the lower end of the permanent magnet is an S pole; or the polarity of the upper end of the permanent magnet (4) is S pole, and the polarity of the lower end of the permanent magnet is N pole.

9. The direct current contactor electromagnetic drive mechanism capable of fast response according to claim 1, characterized in that: an iron core (101) is arranged in an inner cavity of the yoke (1) along the axis of the yoke, the permanent magnet (4) is annular and fixedly sleeved on the iron core (101), the coil (2) is wound on the outer side of the permanent magnet (4) and can slide up and down relative to the permanent magnet (4), and the rotor (3) is fixed at the top of the coil (2);

the polarity of the peripheral surface of the permanent magnet (4) is N pole, and the polarity of the inner peripheral surface of the permanent magnet is S pole; or the polarity of the peripheral surface of the permanent magnet (4) is S pole, and the polarity of the inner peripheral surface of the permanent magnet is N pole.