Magnetic circuit parallel moving magnetic type linear oscillation motor

Abstract

The invention provides a magnetic circuit parallel moving magnetic type cylindrical linear oscillation motor which comprises an inner stator and an outer stator, a rotor is located between the inner stator and the outer stator and comprises permanent magnets, the permanent magnets are divided into a main permanent magnet and auxiliary permanent magnets, and the auxiliary permanent magnets are symmetrically arranged at the two ends of the main permanent magnet. The outer stator comprises an axial magnetic field outer stator and two transverse magnetic field outer stators, the two transverse magnetic field outer stators are symmetrically distributed at the two ends of the axial magnetic field outer stator, the inner stator annular main body, the transverse magnetic circuit outer stator annular main body and the axial magnetic field outer stator annular main body are all of circular ring structures, and the rotor is of a sleeve structure. Compared with a traditional single-phase multi-pole permanent magnet linear oscillation motor, the single-phase multi-pole permanent magnet linear oscillation motor has the advantages that the rotor permanent magnets can be utilized to the greatest extent, the output of the unit permanent magnets is improved under the condition of not increasing the mass of the rotor, and meanwhile, the overall axial length of the motor is kept unchanged, so that the problem that the output of the unit permanent magnets of the existing linear oscillation motor is not high is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of linear motors and relates to a magnetic circuit parallel moving magnet type linear oscillating motor. Background Art

[0002] In the field of compression refrigeration, the most common way is to combine a rotary motor with a crankshaft to drive a piston to achieve linear reciprocating motion. However, this way not only leads to a large number of components and increased costs, but also due to the inevitable frictional losses of the mechanical conversion structure, the efficiency of the entire system is not high. The linear oscillating motor has the advantages of simple structure, high operating frequency, fast response speed, etc. Its mover can directly drive the compressor piston to achieve high-frequency reciprocating motion. Therefore, it is the most competitive solution to replace the traditional compressor.

[0003] Existing linear compressors can be divided into two types according to the assembly method: the transverse flux linear oscillating motor with axially stacked stators and the radial flux linear oscillating motor with circumferentially stacked stators. The stator structure of the transverse flux permanent magnet linear oscillating motor is similar to that of the traditional rotary motor stator. The silicon steel sheets are axially stacked. The number of stator slots of the motor is the same as the number of poles of the mover permanent magnet. Different polar magnetic fields are applied through the armature windings in the stator slots, so as to generate corresponding suction and repulsive forces with the mover permanent magnet, and the linear reciprocating operation of the mover is realized under the action of electromagnetic force. However, although this structure is relatively simple to assemble, the mass of the mover is large and it cannot achieve high-frequency operation. The magnetic circuit direction of the radial flux permanent magnet linear oscillating motor is coplanar with the mover operation direction. Therefore, it is necessary to adopt the method of circumferentially stacking silicon steel sheets to reduce eddy current losses. The stacking coefficient of this stator structure is low, and the output force and power density are not high. Therefore, it is necessary to increase the multi-pole permanent magnet structure to reduce the magnetic resistance in the air-gap magnetic circuit and improve the power density. Summary of the Invention

[0004] 1. Technical problems to be solved: The power density of the existing permanent magnet linear oscillating motor is not high, and the output capacity per permanent magnet needs to be improved. How to achieve a high thrust density for the permanent magnet linear oscillating motor.

[0005] 2. Technical solutions: To solve the above problems, the present invention provides a magnetic circuit parallel moving magnet type cylindrical linear oscillating motor, which includes an inner stator and an outer stator. The mover is located between the inner stator and the outer stator. The mover includes a permanent magnet, which is divided into a main permanent magnet and an auxiliary permanent magnet. The auxiliary permanent magnets are symmetrically arranged at both ends of the main permanent magnet. The outer stator includes an axial magnetic field outer stator and two transverse magnetic field outer stators. The two transverse magnetic field outer stators are symmetrically distributed at both ends of the axial magnetic field outer stator. The inner stator annular body, the transverse magnetic circuit outer stator annular body, and the axial magnetic field outer stator annular body are all circular ring structures. The mover is a sleeve structure.

[0006] The mover includes a mover support iron core and an output shaft. The mover support iron core is fixed on the output shaft. The mover support iron core is a non-magnetic structure, and permanent magnet positioning teeth are reserved on the outer surface. An inner air gap is formed between the mover support iron core and the inner stator. Placement grooves are provided on the mover support iron core according to the sizes of the main permanent magnet and the auxiliary permanent magnet. Both the main permanent magnet and the auxiliary permanent magnet are installed in the placement grooves. Both the main permanent magnet and the auxiliary permanent magnet are made of neodymium iron boron materials in the form of multiple tiles with the same quantity and angle. The main permanent magnet and the auxiliary permanent magnet tiles are centered and aligned during splicing. An outer air gap is formed between the main permanent magnet and the auxiliary permanent magnet and the outer stator.

[0007] The inner stator includes an inner stator annular body, an inner stator positioning ring, and an inner stator support ring. Annular positioning grooves are reserved on both end faces of the inner stator annular body. One end positioning groove cooperates with the protruding teeth in the inner stator positioning ring and is fastened by welding. The other end positioning groove of the inner stator annular body cooperates with the inner stator support ring, so that the inner stator annular body is fixed on the inner stator support ring. The inner stator annular body is integrally machined from a magnetic conductive material, or spliced from multiple sector-shaped magnetic conductive materials, or stacked along the circumferential direction by silicon steel sheets, or spliced from stator blocks composed of multiple silicon steel sheets.

[0008] The transverse magnetic field outer stator annular body is a ring structure. An even number of open slots are evenly distributed along the inner circumference direction. Parallel teeth are located between two open slots. The transverse magnetic field outer stator winding coils are distributed around the parallel teeth. Two transverse magnetic field outer stators are spaced by the positioning rings at the left and right ends of the axial magnetic field outer stator.

[0009] The transverse magnetic field outer stator is integrally machined from a magnetic conductive material, or laminated axially by annular silicon steel sheets. The axial magnetic field outer stator is spliced from stator blocks integrally machined from a magnetic conductive material, or spliced from stator blocks composed of silicon steel sheets.

[0010] The axial magnetic field outer stator body is a ring structure. Annular convex teeth are reserved on both end faces. The assembled complete axial magnetic field outer stator body stator blocks are fixed by the outer stator positioning ring to form a ring structure. An annular installation hole is provided inside the axial magnetic field outer stator body. The axial magnetic field outer stator winding coils are located in the annular installation hole.

[0011] The axial magnetic field outer stator is spliced from stator blocks integrally machined from a magnetic conductive material, or spliced from stator blocks composed of silicon steel sheets.

[0012] The number of main permanent magnet tiles is equal to the number of open slots in the transverse magnetic field outer stator, the number of stator blocks in the axial magnetic field outer stator, and the number of stator blocks in the inner stator.

[0013] The axial length of the axial magnetic field outer stator annular body is equal to the length of the inner stator annular body. The center lines of the main permanent magnet tiles, the stator teeth of the transverse magnetic field outer stator annular body, the stator blocks of the axial magnetic field outer stator annular body, and the stator blocks of the inner stator annular body are kept aligned. The axial length of the transverse magnetic field outer stator annular body is greater than the rated stroke of the motor. The distance between the transverse magnetic field outer stator annular body and the axial magnetic field outer stator annular body is equal to the rated stroke of the motor. The total axial length of the main permanent magnet and the two auxiliary permanent magnets is greater than the spacing between the two transverse magnetic field outer stator annular bodies. The number Np of the main permanent magnet tiles, the number Ns of the transverse magnetic field outer stator slots, the number Nr of the axial magnetic field outer stator silicon steel sheet stator blocks, and the number Ni of the inner stator silicon steel sheet stator blocks satisfy the following relational expression: Np = Ns = Nr = Ni. The center lines of the main permanent magnet tiles, the stator teeth of the transverse magnetic field outer stator annular body, the stator blocks of the axial magnetic field outer stator annular body, and the stator blocks of the inner stator annular body are kept aligned.

[0014] It further includes a housing. Positioning teeth are provided on the inner wall surface of the housing to fix the outer stator inside the housing in the arrangement mode of two transverse magnetic field outer stators in the middle and an axial magnetic field outer stator. A first end cover and a second end cover are respectively arranged at both ends of the housing. Installation holes are provided on both the first end cover and the second end cover. Linear bearings are fixedly connected in the installation holes. The first end cover is fixedly connected with an elastic member, and the other end of the elastic member is fixedly connected with the support of the mover core.

[0015] 3. Beneficial effects: The present invention provides a magnetic circuit parallel moving magnet type linear oscillating motor. The mover of the motor adopts a three-permanent magnet structure, and the polarity of the middle permanent magnet is opposite to that of the permanent magnets at both ends. Compared with the traditional single-phase multi-pole permanent magnet linear oscillating motor, a set of circumferentially laminated silicon steel sheet stators are respectively arranged in the spaces at both ends of the outer stator. A certain number of slots are provided in each stator, and two sets of armature coils are placed in each slot. By generating magnetic fields with different polarities through different currents in the coils, the attraction and repulsion of the mover permanent magnets are realized. Compared with the traditional motor, the motor can make the most of the mover permanent magnets, improve the output of a unit permanent magnet without increasing the mass of the mover, and keep the overall axial length of the motor unchanged, thereby solving the problem of low output of a unit permanent magnet in the existing linear oscillating motor. Description of the drawings

[0016] Figure 1 is a cross-sectional view of the linear oscillating motor of the present invention.

[0017] Figure 2 is an exploded view of the linear oscillating motor of the present invention.

[0018] Figure 3 is a structural diagram of the axial magnetic field outer stator of the present invention.

[0019] Figure 4 This is the structural diagram of the outer stator of the transverse magnetic field of the present invention.

[0020] Figure 5 This is the working principle diagram of the linear oscillating motor of the present invention.

[0021] Description of reference numerals: 1. Inner stator; 11. Inner stator annular body; 12. Inner stator positioning ring; 13. Inner stator support ring; 2. Rotor; 21. Output shaft; 22 Rotor support iron core; 23 Main permanent magnet; 24. Auxiliary permanent magnet; 3. Outer stator; 31 Axial magnetic field outer stator; 311. Axial magnetic field outer stator annular body; 312. Axial magnetic field outer stator winding coil; 313. Axial magnetic field outer stator positioning ring; 32. Transverse magnetic field outer stator; 321. Transverse magnetic field outer stator annular body; 322. Transverse magnetic field outer stator winding coil; 4. Machine shell; 5. First end cover; 6. Second end cover; 7. Linear bearing; 8. Elastic member. Detailed implementation manners

[0022] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0023] A magnetic circuit parallel moving magnet type cylindrical linear oscillating motor, as Figure 1 shown, includes an inner stator 1, a rotor 2, and an outer stator structure. The inner stator 1 includes an inner stator annular body 11, an inner stator positioning ring 12, and an inner stator support ring 13; the rotor 2 includes an output shaft 21, a rotor support iron core 22, a main permanent magnet 23, and an auxiliary permanent magnet 24; the outer stator structure 3 includes an axial magnetic field outer stator 31 and two transverse magnetic field outer stators 32. The axial magnetic field outer stator 31 includes an axial magnetic field outer stator annular body 311, an axial magnetic field outer stator winding coil 312, and an axial magnetic field outer stator positioning ring 313; the transverse magnetic field outer stator 32 includes a transverse magnetic field outer stator annular body 321 and a transverse magnetic field outer stator winding coil 322; the inner stator 1, the rotor 2, the outer stator 3, and the machine shell are coaxially installed.

[0024] As Figure 2 shown, the inner stator annular body 11 is of a ring structure, with annular positioning grooves reserved on both end faces. One end positioning groove is matched with the protruding teeth in the inner stator positioning ring 12 and fastened by welding; the other end positioning groove of the inner stator annular body 11 is matched with the inner stator support ring 13, so that the inner stator annular body 11 is fixed on the inner stator support ring 13, and the other end of the inner stator support ring 13 is fastened to the second end cover 6 by screws.

[0025] In one embodiment, the inner stator annular body 11 is integrally processed from a magnetic conductive material, or spliced from multiple sector-shaped magnetic conductive materials, or stacked from silicon steel sheets along the circumferential direction, or spliced from stator blocks composed of multiple silicon steel sheets.

[0026] As shown Figure 2 in FIG. 2, the mover support core 22 is provided with a placement groove according to the sizes of the main permanent magnet 23 and the auxiliary permanent magnets 24. The main permanent magnet 23 and the symmetrically placed auxiliary permanent magnets are all sleeved in the annular placement groove. The mover support core 22 is fixed on the output shaft 21, and the output shaft 21 is slidably connected to the linear bearings 7 located on the first end cover 5 and the second end cover 6.

[0027] In one embodiment, the main permanent magnet 23 and the auxiliary permanent magnets 24 are made of neodymium iron boron material with an annular structure or a tile structure, and are pasted on the outer surface of the mover support core 22 with glue. The main permanent magnet 23 and the auxiliary permanent magnets 24 are both radially magnetized, and their magnetization directions are opposite.

[0028] As shown Figure 3 in FIG. 3, the axial magnetic field outer stator annular body 311 has an annular structure, and annular convex teeth are reserved on both end faces. The assembled axial magnetic field outer stator body 311 stator blocks are fixed by the outer stator positioning ring 313, so as to form an annular structure. An annular mounting hole is provided inside the axial magnetic field outer stator body 311, and the axial magnetic field outer stator winding coil 312 is located in the annular mounting hole.

[0029] As shown Figure 4 in FIG. 4, the transverse magnetic field outer stator annular body 321 has an annular structure, and an even number of semi-open slots are evenly distributed along the inner circumferential line direction. Parallel teeth are located between two open slots, and the transverse magnetic field outer stator winding coil 322 is distributed around the parallel teeth. Two transverse magnetic field outer stators 32 are symmetrically distributed at both ends of the axial magnetic field outer stator 31, and are spaced by the axial magnetic field outer stator positioning ring 313.

[0030] In one embodiment, it further includes a housing 4. The inner wall surface of the housing 4 is provided with positioning teeth, and the outer stator 3 is fixed inside the housing 4 in the arrangement of two transverse magnetic field outer stators 32 in the middle and an axial magnetic field outer stator 31 on both sides. The first end cover 5 and the second end cover 6 are respectively provided at both ends of the housing. The first end cover 5 and the second end cover are both provided with mounting holes, and linear bearings 7 are tightly connected in the mounting holes.

[0031] The first end cover 6 is tightly connected with an elastic member 8, and the other end of the elastic member 8 is tightly connected with the mover core support 22.

[0032] In one embodiment, both the inner stator annular body 11 and the axial magnetic field outer stator annular body 311 can be integrally cut from a magnetic conductive material, or be spliced by multiple sector-shaped magnetic conductive material blocks, or be formed by stacking silicon steel sheets along the circumferential direction, or be spliced by stator blocks composed of multiple silicon steel sheets. The transverse magnetic field outer stator annular body 321 can be integrally processed from a magnetic conductive material, or be formed by axially laminating annular silicon steel sheets.

[0033] In one embodiment, the inner stator positioning ring 12, the inner stator support ring 13, the axial magnetic field outer stator positioning ring rotor 313, and the rotor support iron core are made of non-magnetic materials. When the structural strength can meet the requirements, the inner stator positioning ring 12, the inner stator support ring 13, the axial magnetic field outer stator positioning ring rotor 313, and the rotor support iron core should be made of non-metallic materials.

[0034] The main permanent magnet 23 and the auxiliary permanent magnet 24 are made of neodymium iron boron material in a ring structure or a tile structure, and are pasted on the outer surface of the rotor support iron core 22 by glue. The main permanent magnet 23 and the auxiliary permanent magnet 24 are both radially magnetized, and their magnetization directions are opposite.

[0035] The number of tiles of the main permanent magnet 23 and the auxiliary permanent magnet 24 in the circumferential direction should be the same as the number of stator teeth of the transverse magnetic field outer stator ring body 311 and the number of stator blocks of the axial magnetic field outer stator ring body 321, and the angles should be equal. During the installation process, the center lines of the tiles of the main permanent magnet 23, the center lines of the tiles of the auxiliary permanent magnet 24, the center lines of the stator teeth of the transverse magnetic field outer stator ring body 311, the center lines of the stator blocks of the axial magnetic field outer stator ring body 321, and the center lines of the stator blocks of the inner stator ring body 11 should be aligned.

[0036] The axial length of the axial magnetic field outer stator ring body 311 is equal to the length of the inner stator ring body 11. The axial length of the transverse magnetic field outer stator ring body 321 is greater than the rated stroke of the motor. The distance between the transverse magnetic field outer stator ring body 321 and the axial magnetic field outer stator ring body 311 is equal to the rated stroke of the motor. The total axial length of the main permanent magnet 23 and the two auxiliary permanent magnets 24 should be greater than the distance between the two transverse magnetic field outer stator ring bodies 321.

[0037] The unilateral transverse magnetic field outer stator winding coil 322 is of the same phase, and the axial magnetic field outer stator winding coil 312 is of one phase. The transverse magnetic field outer stator winding coil 322 and the intermediate axial magnetic field outer stator winding coil 312 can work independently or work together to achieve the maximum electromagnetic force output.

[0038] Figure 5 A schematic diagram of the working principle of the linear oscillating motor of the present invention is given. The dotted line in the figure represents the magnetic field direction, S represents the negative pole of the magnetic field, and N represents the positive pole of the magnetic field. Figure 5As shown in Fig. a, at this time, the mover structure 2 is located at the central position. A current flowing from the upper part to the lower part is passed through the axial magnetic field outer stator winding coil 312. A magnetic field directed to the left is generated in the space surrounded by the axial magnetic field outer stator winding coil 312. This magnetic field interacts with the permanent magnetic field, causing the mover structure to receive an electromagnetic force directed to the left. At the same time, a current is passed through the left-end transverse magnetic field outer stator winding coil 322 to generate a magnetic field directed inwards, so that the left-end transverse magnetic field outer stator ring stator 321 and the left-end auxiliary permanent magnet 24 generate an attractive force directed to the left. The current in the right-end transverse magnetic field outer stator winding coil 322 generates a magnetic field directed outwards, causing the left-end transverse magnetic field outer stator ring stator 321 and the left-end auxiliary permanent magnet 24 to generate a repulsive force directed to the left. The mover structure 2 is pushed to move to the left by the three electromagnetic forces directed to the left. Similarly, as Figure 5 shown in Fig. b, by changing the directions of the currents passed through the transverse magnetic field outer stator winding coil 322 and the axial magnetic field outer stator winding coil 312, an electromagnetic force directed to the right can be generated on the mover structure 2, thus realizing the rightward movement of the mover structure 2.

Claims

1. A magnetic circuit parallel-acting magnetic cylindrical linear oscillation motor, comprising an inner stator (1) and an outer stator (3), wherein a mover (2) is located between the inner stator (1) and the outer stator (3), and characterized in that: The mover (2) comprises a permanent magnet, which is divided into a main permanent magnet (23) and an auxiliary permanent magnet (24), the auxiliary permanent magnet (24) being symmetrically arranged at both ends of the main permanent magnet (23), the outer stator (3) comprising an axial magnetic field outer stator (31) and two transverse magnetic field outer stators (32), the two transverse magnetic field outer stators (32) being symmetrically distributed at both ends of the axial magnetic field outer stator 31, the inner stator annular body (11), the transverse magnetic circuit outer stator annular body (311) and the axial magnetic field outer stator annular body (321) are all annular structures, and the mover (2) is a sleeve structure.

2. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor according to claim 1, characterized in that: The mover (2) comprises a mover support core (22) and an output shaft (21). The mover support core (22) is fixed on the output shaft (21). The mover support core (22) is a non-magnetic structure, and permanent magnet positioning teeth are reserved on the outer surface. An inner air gap is formed between the mover support core (22) and the inner stator (1). A placement groove is provided on the mover support core (22) according to the size of the main permanent magnet (23) and the auxiliary permanent magnet (24). The main permanent magnet (23) and the auxiliary permanent magnet (24) are both installed in the placement groove. The main permanent magnet (23) and the auxiliary permanent magnet (24) are both multiple pieces of neodymium iron boron material with the same number and angle of tile structure. The main permanent magnet (23) and the auxiliary permanent magnet (24) tiles are kept centrally aligned during splicing. An outer air gap is formed between the main permanent magnet (23) and the auxiliary permanent magnet (24) and the outer stator (3).

3. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor according to claim 1 or 2, characterized in that: The inner stator (1) comprises an inner stator annular body (11), an inner stator positioning ring (12) and an inner stator support ring (13); annular positioning grooves are reserved on both end surfaces of the inner stator annular body (11); the positioning groove at one end cooperates with a raised tooth in the inner stator positioning ring (12) and is fastened by welding; the positioning groove at the other end of the inner stator annular body (12) cooperates with the inner stator support ring (13), so that the inner stator annular body (11) is fixed on the inner stator support ring (13); the inner stator annular body (11) is made of a magnetic conductive material in one piece, or is formed by splicing a plurality of sector-shaped magnetic conductive materials, or is formed by stacking silicon steel sheets in a circumferential direction, or is formed by splicing stator blocks composed of a plurality of silicon steel sheets.

4. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor according to claim 1 or 2, characterized in that: The transverse magnetic field outer stator annular body (321) is an annular structure, with an even number of open slots evenly distributed along the inner circumference line direction, parallel teeth are located between two open slots, and the transverse magnetic field outer stator winding coils (322) are distributed around the parallel teeth.

5. The two transverse magnetic field outer stators (32) are spaced apart by positioning rings (313) at the left and right ends of the axial magnetic field outer stator.

6. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor according to claim 4, characterized in that: The transverse magnetic field outer stator (32) is made by machining a magnetic conductive material in one piece, or is made by stacking annular silicon steel sheets in the axial direction.

7. The axial magnetic field outer stator is formed by splicing stator blocks made of magnetic conductive materials or by splicing stator blocks composed of silicon steel sheets. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor as claimed in claim 3 is characterized in that: The axial magnetic field outer stator body (311) is an annular structure, with annular convex teeth reserved on both end surfaces, and the stator block of the completely assembled axial magnetic field outer stator body (311) is fixed by an outer stator positioning ring (313), thereby realizing an annular structure, and an annular mounting hole is provided in the axial magnetic field outer stator body (311), and the axial magnetic field outer stator winding coil (312) is located in the annular mounting hole.

8. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor according to claim 3, characterized in that: The axial magnetic field outer stator (31) is formed by splicing stator blocks made of magnetic conductive materials in one piece, or by splicing stator blocks made of silicon steel sheets. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor as described in claim 7 is characterized in that the number of main permanent magnet (23) tiles, the number of open slots of the transverse magnetic field outer stator (32), the number of stator blocks of the axial magnetic field outer stator (31), and the number of stator blocks of the inner stator (1) are equal.

9. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor according to claim 7, characterized in that: The axial length of the axial magnetic field outer stator annular body (311) is equal to the length of the inner stator annular body (11), the axial length of the transverse magnetic field outer stator annular body (321) is greater than the rated stroke of the motor, the distance between the transverse magnetic field outer stator annular body (321) and the axial magnetic field outer stator annular body (311) is equal to the rated stroke of the motor, the total axial length of the main permanent magnet (23) and the two auxiliary permanent magnets (24) is greater than the spacing between the two transverse magnetic field outer stator annular bodies (321), the number Np of main permanent magnet tiles, the number Ns of transverse magnetic field outer stator slots, the number Nr of axial magnetic field outer stator silicon steel sheet stator blocks, and the number Ni of inner stator silicon steel sheet stator blocks satisfy the following relationship: Np=Ns=Nr=Ni, and the center line of the main permanent magnet tile, the center line of the stator teeth of the transverse magnetic field outer stator annular body, the center line of the stator block of the axial magnetic field outer stator annular body, and the center line of the stator block of the inner stator annular body are aligned.

10. The magnetic circuit parallel moving magnet type cylindrical linear oscillation motor according to claim 3, characterized in that: The invention also comprises a casing (4), wherein the inner wall surface of the casing (4) is provided with positioning teeth, and the outer stator (3) is fixed inside the casing (4) in an arrangement manner in which the outer stators (32) for the transverse magnetic field are arranged on both sides and the outer stator (31) for the axial magnetic field is arranged in the middle; a first end cover (5) and a second end cover (6) are respectively arranged at two ends of the casing (4); the first end cover (5) and the second end cover (6) are both provided with mounting holes, and a linear bearing (7) is fastened to the mounting hole; the first end cover (6) is fastened to an elastic member (8), and the other end of the elastic member (8) is fastened to a mover core support (22).

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