Magnetic exhaust valve

Abstract

The utility model belongs to the technical field of exhaust valves, and particularly relates to a magnetic exhaust valve. In order to overcome the defect that a valve element is abraded due to the fact that a pair of repellent magnetic parts is adopted in an existing magnetic exhaust valve and the valve element is prone to deflection in the moving process, the magnetic exhaust valve comprises a valve seat, an exhaust hole, a valve rod and a valve rod, the exhaust valve core moves axially and is provided with a sealing part for opening and closing the exhaust hole; the guide seat is fixedly arranged; the first magnetic part is fixed on the guide seat; the second magnetic part moves axially and is far away from the exhaust hole in the axial direction compared with the exhaust valve element and the first magnetic part; an axial guide structure is formed between the exhaust valve element and the guide seat; attractive magnetic force is generated between the first magnetic part and the second magnetic part, so that the exhaust valve element moves towards the exhaust hole. According to the magnetic exhaust valve, abrasion of the exhaust valve element can be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of exhaust valves, and particularly relates to a magnetic exhaust valve. Background Art

[0002] The applicant's prior utility model patent (publication number CN218644813U) discloses a magnetic exhaust valve, which includes: a valve seat provided with an exhaust hole; an exhaust valve core axially movable in the exhaust hole; a first magnetic member provided at one end of the exhaust valve core away from the exhaust hole; a guide seat arranged along the axial direction of the exhaust hole; a second magnetic member fixed on the guide seat; wherein, an axial guiding structure is formed between the exhaust valve core and the guide seat; and wherein, a mutually repulsive magnetic force is generated between the first magnetic member and the second magnetic member. The magnetic exhaust valve of this utility model realizes a magnetic structure on the exhaust valve.

[0003] However, through experiments and analysis, the applicant found that in the solution of the aforementioned utility model, due to the repulsion between the first magnetic member and the second magnetic member, it is difficult to keep the first magnetic member and the second magnetic member on the same center line without external constraints. The problems arising therefrom are: the valve core and the first magnetic member will deflect during the reciprocating movement, resulting in relatively fast wear of the valve core. In addition, in order to prevent the two magnetic members from coming off, the assembly is also rather troublesome. Summary of the Invention

[0004] Aiming at the deficiency of the existing magnetic exhaust valve that uses a pair of mutually repulsive magnetic members, and the valve core is prone to deflection during the movement, resulting in wear of the valve core, the utility model provides a magnetic exhaust valve that uses a pair of mutually attractive magnetic members to avoid or reduce the deflection of the valve core during the movement, thereby avoiding or reducing the wear of the valve core.

[0005] To achieve the above object, the utility model adopts the following technical scheme: a magnetic exhaust valve, which includes:

[0006] A valve seat, fixedly arranged, provided with an exhaust hole;

[0007] An exhaust valve core, axially movable, having a sealing portion for opening and closing the exhaust hole;

[0008] A guide seat, fixedly arranged;

[0009] A first magnetic member, sleeved on the guide seat;

[0010] A second magnetic member, axially movable, axially farther away from the exhaust hole than the exhaust valve core and the first magnetic member;

[0011] Wherein, an axial guiding structure is formed between the exhaust valve core and the guide seat;

[0012] Wherein, an attractive magnetic force that causes the exhaust valve core to move toward the exhaust hole is generated between the first magnetic member and the second magnetic member.

[0013] The magnetic exhaust valve of the present utility model includes a valve seat, an exhaust valve core, a guide seat, a first magnetic member, and a second magnetic member. The first magnetic member is fixed, and the second magnetic member is axially away from the exhaust hole compared with the exhaust valve core and the first magnetic member, so as to realize that the first magnetic member and the second magnetic member generate an attractive magnetic force to push the exhaust valve core toward the exhaust hole and seal the exhaust hole. The magnetic structure not only has the advantage that the exhaust valve core in the spring structure closes sensitively, but also avoids the fracture and failure phenomenon of the spring structure. It has a simple structure, a long service life, and high operating reliability. An axial guiding structure is formed between the exhaust valve core and the guide seat to ensure reliable axial reciprocation of the exhaust valve core and the first magnetic member. Compared with the repulsive structure, the attractive structure can ensure that the force on the exhaust valve core is the same as the axis direction without deflection, thereby reducing the wear of the exhaust valve core.

[0014] As an improvement, a guide hole portion is formed at one end of the guide seat close to the exhaust hole, a guide hole is opened in the guide hole portion, a guide portion that cooperates with the guide hole is formed at one end of the exhaust valve core away from the exhaust hole, and the guide portion is inserted into the guide hole to form the axial guiding structure.

[0015] As an improvement, the first magnetic member is sleeved on the guide hole portion; the guide portion and the guide hole are in clearance fit; one end of the guide portion away from the exhaust hole is always farther from the exhaust hole than the guide hole portion. The first magnetic member and the guide hole portion adopt one of the three shaft-hole fit methods (i.e., clearance fit, transition fit, or interference fit), and the difference between the inner diameter of the first magnetic member and the outer diameter of the wire hole portion is small to avoid radial displacement of the first magnetic member.

[0016] As an improvement, a receiving portion is formed at one end of the guide seat away from the exhaust port, the radial dimension of the receiving portion is larger than the radial dimension of the guide hole portion, a receiving cavity communicating with the guide hole is opened in the receiving portion, and the opening of the receiving cavity is away from the exhaust port.

[0017] As an improvement, the magnetic exhaust valve further includes a T-shaped member, the T-shaped member includes a large-diameter portion close to the first magnetic member and a small-diameter portion away from the first magnetic member, and the second magnetic member is tightly sleeved on the small-diameter portion.

[0018] As an improvement, an annular convex portion is formed by extending the outside of the receiving portion of the guide seat, and the annular convex portion is adjacent to the guide hole portion.

[0019] As an improvement, the accommodation cavity guides the large-diameter part axially, and the large-diameter part is in clearance fit with the accommodation cavity, and / or, the accommodation cavity guides the second magnetic member axially, and the second magnetic member is in clearance fit with the accommodation cavity; and / or,

[0020] The exhaust valve core, the guide seat and the T-shaped member are all made of polyether ether ketone material.

[0021] As an improvement, the magnetic exhaust valve further includes a buffer pad. The buffer pad is farther away from the exhaust hole than the guide seat. The axial dimension of the small-diameter part is greater than the axial dimension of the second magnetic member. When the small-diameter part abuts against the buffer pad, the exhaust valve core reaches the limit position. At this time, there is an axial gap between the sealing part of the exhaust valve core and the guide seat.

[0022] As an improvement, the T-shaped member is butt-jointed with the end face of the exhaust valve core.

[0023] As an improvement, when the magnetic exhaust valve is erected, a tapered hole with a larger upper part and a smaller lower part is opened on the valve seat, and the exhaust valve core includes the sealing part with a tapered shape with a larger upper part and a smaller lower part; and / or,

[0024] Both the first magnetic member and the second magnetic member are permanent magnets; and / or,

[0025] Both the first magnetic member and the second magnetic member are in the shape of a circular ring.

[0026] The beneficial effects of the magnetic exhaust valve of the present utility model are as follows: The first magnetic member is fixed, and the second magnetic member is axially away from the exhaust hole compared with the exhaust valve core and the first magnetic member, so as to realize that the first magnetic member and the second magnetic member generate an attractive magnetic force to push the exhaust valve core to move towards the exhaust hole and seal the exhaust hole; The magnetic structure not only has the advantage of sensitive closing of the exhaust valve core in the spring structure, but also avoids the fracture and failure phenomenon of the spring structure; The structure is simple, the service life is long, and the operation reliability is high; An axial guiding structure is formed between the exhaust valve core and the guide seat to ensure reliable axial reciprocation of the exhaust valve core and the first magnetic member; Compared with the repulsive structure, the attractive structure can ensure that the force on the exhaust valve core is the same as the axis direction without deflection, thereby reducing the wear of the exhaust valve core. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0028] Figure 2 It is a cross-sectional view (sealing state) of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0029] Figure 3 It is a cross-sectional view (exhaust state) of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0030] Figure 4 It is an exploded view of the structure of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0031] Figure 5 It is a schematic structural view of the valve seat of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0032] Figure 6 It is a schematic structural view of the exhaust valve core of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0033] Figure 7 It is a schematic structural view of the first magnetic member of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0034] Figure 8 It is a schematic structural view of the guide seat of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0035] Figure 9 It is a schematic structural view of the second magnetic member of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0036] Figure 10 It is a schematic structural view of the T-shaped member of the magnetic exhaust valve according to the first embodiment of the present utility model.

[0037] Figure 11 It is a schematic structural view when the magnetic exhaust valve according to the first embodiment of the present utility model is installed on the end cover of the recycling machine.

[0038] In the figure, 1, valve seat; 11, exhaust hole; 12, intake hole;

[0039] 2, exhaust valve core; 21, sealing part; 22, guiding part;

[0040] 3, first magnetic member;

[0041] 4, guide seat; 41, guide hole part; 42, accommodating part; 43, annular convex part;

[0042] 5, second magnetic member;

[0043] 6, T-shaped member; 61, large diameter part; 62, small diameter part;

[0044] 7, buffer pad;

[0045] 8, end cover. Detailed implementation manners

[0046] Combined with the accompanying drawings of the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be explained and described. However, the following embodiments are only the preferred embodiments of the present invention, not all of them. Based on the embodiments in the implementation manner, other embodiments obtained by those skilled in the art without creative efforts all belong to the protection scope of the present invention.

[0047] See Figures 1 to 11 , a magnetic exhaust valve of the present utility model, the magnetic exhaust valve includes:

[0048] A valve seat, fixedly arranged, provided with an exhaust hole;

[0049] An exhaust valve core, axially movable, having a sealing portion for opening and closing the exhaust hole;

[0050] A guide seat, fixedly arranged;

[0051] A first magnetic member, sleeved on the guide seat;

[0052] A second magnetic member, axially movable, axially away from the exhaust hole compared with the exhaust valve core and the first magnetic member;

[0053] Wherein, an axial guiding structure is formed between the exhaust valve core and the guide seat;

[0054] Wherein, an attracting magnetic force is generated between the first magnetic member and the second magnetic member, so that the exhaust valve core moves towards the exhaust hole.

[0055] The magnetic exhaust valve of the present utility model includes a valve seat, an exhaust valve core, a guide seat, a first magnetic member, and a second magnetic member. The first magnetic member is fixed, and the second magnetic member is axially away from the exhaust hole compared with the exhaust valve core and the first magnetic member, so as to realize that the first magnetic member and the second magnetic member generate an attracting magnetic force to push the exhaust valve core towards the exhaust hole and seal the exhaust hole; the magnetic structure not only has the advantage of sensitive closing of the exhaust valve core in the spring structure, but also avoids the fracture and failure phenomenon of the spring structure; the structure is simple, the service life is long, and the operation reliability is high; an axial guiding structure is formed between the exhaust valve core and the guide seat to ensure reliable axial reciprocation of the exhaust valve core and the first magnetic member; the attracting structure can ensure that the force on the exhaust valve core is the same as the axis without deflection compared with the repulsive structure, thereby reducing the wear of the exhaust valve core.

[0056] Embodiment 1

[0057] See Figures 1 to 11 , a magnetic exhaust valve of Embodiment 1 of the present utility model, the magnetic exhaust valve includes:

[0058] A valve seat 1, fixedly arranged, provided with an exhaust hole 11;

[0059] The exhaust valve core 2 is axially movable and has a sealing portion 21 for opening and closing the exhaust hole 11;

[0060] The guide seat 4 is fixedly arranged;

[0061] The first magnetic member 3 is sleeved on the guide seat 4;

[0062] The second magnetic member 5 is axially movable and axially away from the exhaust hole 11 compared with the exhaust valve core 2 and the first magnetic member 3;

[0063] Wherein, an axial guiding structure is formed between the exhaust valve core 2 and the guide seat 4;

[0064] Wherein, an attracting magnetic force is generated between the first magnetic member 3 and the second magnetic member 5, so that the exhaust valve core 2 moves towards the exhaust hole 11.

[0065] See Figure 11 , in this embodiment, when the magnetic exhaust valve is installed on the end cover 8 of the recycling machine, the magnetic exhaust valve is erected, a tapered hole with a larger upper part and a smaller lower part is formed on the valve seat 1, and the exhaust valve core 2 includes the sealing portion 21 which is tapered with a larger upper part and a smaller lower part. An air inlet hole 12 is also formed on the valve seat 1, and the air inlet hole 12 is a tapered hole with a larger lower part and a smaller upper part.

[0066] See Figure 2 , Figure 3 and Figure 8 , in this embodiment, a guide hole portion 41 is formed at one end of the guide seat 4 close to the exhaust hole 11, a guide hole is formed in the guide hole portion 41, a guide portion 22 matched with the guide hole is formed at one end of the exhaust valve core 2 away from the exhaust hole 11, and the guide portion 22 is inserted into the guide hole to form the axial guiding structure.

[0067] In this embodiment, the first magnetic member 3 is loosely sleeved on the guide hole portion 41 (with clearance fit) to facilitate the assembly between the first magnetic member 3 and the guide hole portion 41. In other embodiments, the first magnetic member can also be tightly sleeved on the guide hole portion (with interference fit or transition fit). To avoid radial displacement of the first magnetic member 3 and ensure that the attracting magnetic force between the first magnetic member 3 and the second magnetic member 5 is along the axis of the exhaust hole 11, the aperture of the first magnetic member 3 and the outer diameter of the guide hole portion 41 should not differ too much.

[0068] In this embodiment, the guide portion 22 and the guide hole have clearance fit; one end of the guide portion 22 away from the exhaust hole 11 is always farther from the exhaust hole 11 than the guide hole portion 41.

[0069] In this embodiment, a receiving portion 42 is formed at one end of the guiding seat 4 away from the exhaust port. The radial dimension of the receiving portion 42 is larger than that of the guiding hole portion 41. A receiving cavity communicating with the guiding hole is formed in the receiving portion 42, and the opening of the receiving cavity is away from the exhaust port.

[0070] In this embodiment, the magnetic exhaust valve further includes a T-shaped member 6. The T-shaped member 6 includes a large-diameter portion 61 close to the first magnetic member 3 and a small-diameter portion 62 away from the first magnetic member 3. The second magnetic member 5 is tightly sleeved on the small-diameter portion 62.

[0071] See Figure 8 and Figure 11 , in this embodiment, an annular convex portion 43 is formed by extending the outer side of the receiving portion 42 of the guiding seat 4. The annular convex portion 43 is adjacent to the guiding hole portion 41. An installation hole for the guiding seat 4 is formed on the end cover 8. The installation hole is a stepped hole, and its small-diameter section is in clearance fit with the receiving portion 42, and its large-diameter section is in interference fit with the annular convex portion 43, so as to ensure the normal guiding of the guiding seat 4 to the T-shaped member 6.

[0072] See Figure 2 and Figure 3 , in this embodiment, the receiving cavity guides the axial direction of the large-diameter portion 61, and the large-diameter portion 61 is in clearance fit with the receiving cavity, and / or the receiving cavity guides the axial direction of the second magnetic member 5, and the second magnetic member 5 is in clearance fit with the receiving cavity.

[0073] In this embodiment, the exhaust valve core 2, the guiding seat 4 and the T-shaped member 6 are all made of polyether ether ketone (PEEK) material.

[0074] In this embodiment, the magnetic exhaust valve further includes a buffer pad 7. The buffer pad 7 is farther away from the exhaust hole 11 than the guiding seat 4. The axial dimension of the small-diameter portion 62 is larger than the axial dimension of the second magnetic member 5. When the small-diameter portion 62 abuts against the buffer pad 7, the exhaust valve core 2 reaches the limit position, and at this time, there is an axial gap between the sealing portion 21 of the exhaust valve core 2 and the guiding seat 4.

[0075] In this embodiment, the T-shaped member 6 is butt-jointed with the end face of the exhaust valve core 2, and the end faces of the T-shaped member 6 and the exhaust valve core 2 are in contact only under the action of magnetic force to facilitate disassembly and assembly. In other embodiments, the T-shaped member 6 and the exhaust valve core 2 can also be connected by bonding, plugging, etc.

[0076] In this embodiment, both the first magnetic member 3 and the second magnetic member 5 are permanent magnets.

[0077] In this embodiment, both the first magnetic member 3 and the second magnetic member 5 are in the shape of a circular ring.

[0078] See Figure 11 In this embodiment, the process of installing the magnetic exhaust valve onto the end cap 8 of the recycling machine mainly includes: First, the end cap 8 can be inverted, and the buffer pad 7 is installed into the end cap 8. After the buffer pad 7 is installed, the second magnetic member 5 and the T-shaped member 6 are sleeved together and placed into the accommodating cavity of the guide seat 4. The first magnetic member 3 is sleeved onto the guide hole portion 41 of the guide seat 4. Then, the second magnetic member 5, the T-shaped member 6, the guide seat 4, and the first magnetic member 3 are installed into the end cap 8. Secondly, the guide portion 22 of the exhaust valve core 2 is inserted into the guide hole of the guide hole portion 41 of the guide seat 4. Preferably, the valve seat 1 is installed (the intake valve is installed first before installing the valve seat 1).

[0079] The working principle of the magnetic exhaust valve in this embodiment is as follows: In the initial state, the first magnetic member 3 and the second magnetic member 5 attract each other. The second magnetic member 5 transmits the force to the exhaust valve core 2 through the T-shaped member 6, causing the exhaust valve core 2 to seal the exhaust hole 11 of the valve seat 1 (the gravity of the second magnetic member 5, the T-shaped member 6, and the exhaust valve core 2 also plays a role). When the recycling machine is working, the generated pressure is greater than the magnetic force between the first magnetic member 3 and the second magnetic member 5 (plus the gravity sum of the second magnetic member 5, the T-shaped member 6, and the exhaust valve core 2), so that the exhaust valve core 2, the second magnetic member 5, and the T-shaped member 6 are lifted, and the exhaust hole 11 is opened for exhaust. When the exhaust is completed, when the pressure on the exhaust valve core 2 is less than the magnetic force plus the gravity of the second magnetic member 5, the T-shaped member 6, and the exhaust valve core 2, under the action of the magnetic force and gravity, the exhaust valve core 2 reseals the exhaust hole 11 again. During the process of the exhaust valve core 2 moving towards the exhaust hole 11, since the force generated between the first magnetic member 3 and the second magnetic member 5 is an attractive force, it can ensure that the force generated on the exhaust valve core 2 is always along the axis of the exhaust hole 11, avoiding the deflection of the exhaust valve core 2, and ultimately avoiding or reducing the wear of the exhaust valve core 2 and prolonging the service life of the exhaust valve core 2.

[0080] The beneficial effects of the magnetic exhaust valve according to the first embodiment of the present utility model are as follows: The first magnetic member 3 is fixed, and the second magnetic member 5 is axially away from the exhaust hole 11 compared with the exhaust valve core 2 and the first magnetic member 3, so that the first magnetic member 3 and the second magnetic member 5 generate an attractive magnetic force to push the exhaust valve core 2 towards the exhaust hole 11 and seal the exhaust hole 11; The magnetic structure not only has the advantage of sensitive closing of the exhaust valve core 2 in the spring structure, but also avoids the fracture and failure phenomenon of the spring structure; It has a simple structure, a long service life and high operation reliability; An axial guiding structure is formed between the exhaust valve core 2 and the guiding seat 4 to ensure reliable axial reciprocation of the exhaust valve core 2 and the first magnetic member 3; Compared with the repulsive structure, the attractive structure can ensure that the force on the exhaust valve core 2 is the same as the axis of the exhaust hole 11 without deviation, thereby reducing the wear of the exhaust valve core 2 and prolonging the service life of the exhaust valve core 2; During the exhaust process, by setting the buffer pad 7 and the T-shaped member 6, the T-shaped member 6 collides with the buffer pad 7, and the T-shaped member 6 and the buffer pad 7 bear the impact, reducing or avoiding the impact on the exhaust valve core 2; There is no need for a clamping structure, and the components are installed in a plug-in manner (some need interference fit), which is easy to disassemble and assemble.

[0081] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the content described in the above specific implementation manner. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A magnetic exhaust valve, characterized in that: The magnetic exhaust valve includes: A valve seat (1), fixedly arranged, with an exhaust hole (11) formed thereon; An exhaust valve core (2), axially movable, having a sealing portion (21) for opening and closing the exhaust hole (11); A guide seat (4), fixedly arranged; A first magnetic member (3), sleeved on the guide seat (4); A second magnetic member (5), axially movable, axially farther from the exhaust hole (11) than the exhaust valve core (2) and the first magnetic member (3); Wherein, an axial guiding structure is formed between the exhaust valve core (2) and the guide seat (4); Wherein, an attracting magnetic force that causes the exhaust valve core (2) to move towards the exhaust hole (11) is generated between the first magnetic member (3) and the second magnetic member (5).

2. The magnetic exhaust valve according to claim 1, wherein: One end of the guide seat (4) close to the exhaust hole (11) forms a guide hole portion (41), the guide hole portion (41) is provided with a guide hole, one end of the exhaust valve core (2) far from the exhaust hole (11) forms a guiding portion (22) matching with the guide hole, and the guiding portion (22) is inserted into the guide hole to form the axial guiding structure.

3. The magnetic exhaust valve according to claim 2, characterized in that: The first magnetic member (3) is sleeved on the guide hole portion (41); the guiding portion (22) and the guide hole are in clearance fit; one end of the guiding portion (22) far from the exhaust hole (11) is always farther from the exhaust hole (11) than the guide hole portion (41).

4. A magnetic exhaust valve according to claim 2, characterized in that: One end of the guide seat (4) far from the exhaust port (11) forms a receiving portion (42), the radial dimension of the receiving portion (42) is larger than that of the guide hole portion (41), the receiving portion (42) is provided with a receiving cavity communicating with the guide hole, and the opening of the receiving cavity is far from the exhaust port (11).

5. A magnetic exhaust valve according to claim 4, characterized in that: The magnetic exhaust valve further includes a T-shaped member (6), the T-shaped member (6) includes a large-diameter portion (61) close to the first magnetic member (3) and a small-diameter portion (62) far from the first magnetic member (3), and the second magnetic member (5) is tightly sleeved on the small-diameter portion (62).

6. A magnetic exhaust valve according to claim 4, characterized in that: An annular convex portion (43) is formed by extending the outer side of the receiving portion (42) of the guide seat (4), and the annular convex portion (43) is adjacent to the guide hole portion (41).

7. The magnetic exhaust valve according to claim 5, characterized in that: The receiving cavity guides the axial direction of the large-diameter portion (61), the large-diameter portion (61) is in clearance fit with the receiving cavity, and / or, the receiving cavity guides the axial direction of the second magnetic member (5), the second magnetic member (5) is in clearance fit with the receiving cavity; and / or, The exhaust valve core (2), the guide seat (4) and the T-shaped member (6) are all made of polyether ether ketone material.

8. A magnetic exhaust valve according to claim 5, characterized in that: The magnetic exhaust valve further includes a buffer pad, the buffer pad is farther from the exhaust hole (11) than the guide seat (4), the axial dimension of the small-diameter portion (62) is larger than the axial dimension of the second magnetic member (5), when the small-diameter portion (62) abuts against the buffer pad, the exhaust valve core (2) reaches the limit position, and at this time, there is an axial gap between the sealing portion (21) of the exhaust valve core (2) and the guide seat (4).

9. The magnetic exhaust valve according to claim 5, wherein: The T-shaped part (6) is butt-jointed with the end face of the exhaust valve core (2).

10. A magnetic exhaust valve according to claim 1, characterized in that: When the magnetic exhaust valve is arranged vertically, a tapered hole with a larger upper part and a smaller lower part is formed in the valve seat (1), and the exhaust valve core (2) includes the sealing part (21) with a tapered shape that is larger at the upper part and smaller at the lower part; and / or, Both the first magnetic member (3) and the second magnetic member (5) are permanent magnets; and / or, Both the first magnetic member (3) and the second magnetic member (5) are in an annular shape.

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