KR102175371B1 - Linerar motor and linear compressor having the same - Google Patents

Abstract

A linear motor and a linear compressor including the same according to the present invention include: a stator having a plurality of air gaps in the axial direction between an outer stator and an inner stator; A winding coil provided in the stator; A mover provided between the outer stator and the inner stator and provided with a mover core made of a magnetic material to reciprocate within the void; And a plurality of magnets each fixed to the inner stator so as to be respectively positioned in the plurality of voids, wherein the plurality of magnets are disposed to be spaced apart from each other with a central core interposed therebetween, thereby reducing restoring force to the mover core. Instead, the thrust increases and the motor power can be increased. In addition, as it is applied to a two-pore motor, it is possible to easily control the mover core and to assemble and magnetize the magnet.

Description

Linear motor and linear compressor equipped with the same {LINERAR MOTOR AND LINEAR COMPRESSOR HAVING THE SAME}

The present invention relates to a linear motor in which a mover performs linear reciprocating motion, and a linear compressor having the same.

A linear motor is a motor in which a mover makes a linear reciprocating motion by interaction with a stator, and a linear compressor is a compressor in which a piston is coupled to the mover by employing this linear motor. Therefore, the linear compressor performs a compression stroke that moves to the bottom dead center (BDC) while the piston coupled to the mover reciprocates in the cylinder and moves to the top dead center (TDC). Is done.

The linear motor includes a core through which magnetic flux flows, a winding coil to which current is applied, and a magnet forming a magnetic circuit together with them. In the core, an inner core and an outer core each formed in a cylindrical shape are provided on the inner and outer sides with an air gap. The winding coil is provided on the inner core or the outer core, and the magnet is coupled to the mover or to the core.

Linear motors can be classified into two-pore motors or one-pore motors according to the number of voids provided in the core. The two-gap motor is disclosed in Patent Document 1 (Korean Patent Laid-Open Patent No. 10-2016-0132665 A), and the one-gap motor is disclosed in Patent Document 2 (Korean Patent Publication No. 10-2018-0088121 A).

In the two-pore motor, both ends of the inner core and the outer core are spaced apart from each other to form two voids. Magnets are provided in both air gaps, so that the mover reciprocates by the magnetic flux formed in the core.

In the one-pore motor, one end of the inner core and the outer core are connected and the other end is spaced apart from each other to form one void. A magnet is provided in the void, and the mover makes a reciprocating motion by the magnetic flux formed in the core.

In such a linear motor, since the mover makes a reciprocating motion, the weight of the mover is closely related to the efficiency of the motor. In the structure in which the magnet is coupled to the movable member, a high magnetic Nd magnet is mainly applied. Nd magnets have a high magnetic force but a high price, which increases the manufacturing cost of motors and compressors. Thus, a ferrite magnet of low power is applied. Ferrite magnets are inexpensive, but their magnetic force is weak, requiring a relatively large amount of magnets, which increases the weight of the mover. Therefore, in the case of applying a ferrite magnet, the magnet is coupled to the core forming the stator and the mover core is provided with a magnetic material to reduce the weight of the mover. Patent Document 2 discloses an example in which a plurality of ferrite magnets magnetized in different directions are applied to an outer core constituting a stator in a one-pore motor.

However, when the ferrite magnet is applied to the outer core forming the stator as described above, as the plurality of magnets are magnetized in different directions, the centering force to restore the mover to the center (stator center) with the ruler increases. do. This has a problem in that the thrust pushing the mover in the direction of the top dead center or the bottom dead center is weakened, and the performance of the compressor to which this motor is coupled is deteriorated.

In addition, in the conventional linear motor, as one air gap is formed eccentrically from the center of the magnetic path, the alpha waveform is formed asymmetrically, the inductance increases, the control characteristics of the motor deteriorate, and the motor efficiency decreases.

In addition, the conventional linear motor has a problem that a magnet is mounted on the inner peripheral surface of the core, making it difficult to perform a magnetization operation on the magnet. In particular, as a plurality of magnets are magnetized in different directions, there is a problem that the magnetization operation on the aforementioned magnet becomes more difficult.

Publication Patent Publication KR10-2016-0132665 A (published on November 21, 2016) Unexamined Patent Publication KR10-2018-0088121 A (published on Aug. 3, 2018)

An object of the present invention is to provide a linear motor capable of improving motor efficiency while reducing the amount of use of a magnet by increasing thrust, and a linear compressor having the same.

Further, an object of the present invention is to provide a linear motor capable of increasing thrust for a mover by fixing a plurality of magnets along the axial direction of the stator, but lowering the restoring force formed around the magnets, and a linear compressor having the same.

Further, the present invention is a linear motor capable of increasing motor output while reducing the amount of use of magnets by providing a core made of a magnetic material between the plurality of magnets while increasing thrust by magnetizing a plurality of magnets in the same direction, and a linear motor having the same. It is intended to provide a compressor.

In addition, another object of the present invention is to provide a linear motor capable of improving motor efficiency by increasing control characteristics of the motor when at least two or more magnets are fixed to a stator, and a linear compressor having the same.

Further, an object of the present invention is to provide a linear motor capable of improving the alpha waveform and increasing the control characteristic of the motor by increasing the effective stroke range of the mover, and a linear compressor having the same.

Further, the present invention is to provide a linear motor capable of improving an alpha value and widening an effective stroke range by optimizing the length of a mover core, and a linear compressor having the same.

In addition, another object of the present invention is to provide a linear motor capable of easily magnetizing a magnet while simultaneously coupling a magnet to a stator, and a linear compressor having the same.

Further, the present invention is to provide a linear motor capable of coupling a magnet to an outer circumferential surface of a stator to facilitate coupling and magnetizing the magnet, and a linear compressor having the same.

Furthermore, an object of the present invention is to provide a linear motor capable of facilitating coupling and magnetizing operations by coupling two or more magnets to the outer circumferential surface of a stator, and spaced apart both magnets, and a linear compressor having the same.

In order to achieve the object of the present invention, a plurality of magnets are coupled to a stator equipped with a winding coil, and a mover core made of a magnetic material instead of a permanent magnet is provided on the mover, and the plurality of magnets are magnetized in the same direction. A linear motor and a linear compressor having the same may be provided.

Here, the magnet may be made of a ferrite magnet.

In addition, the stator may be formed of an outer stator and an inner stator, and the plurality of magnets may be provided by being inserted into an outer peripheral surface of the inner stator.

In addition, a core portion protruding toward the outer stator is extended to the inner stator, and the core portion may be positioned between the plurality of magnets.

In addition, the mover core may be provided within the range of the magnet.

In addition, the stator may be formed such that air gaps are respectively located on both sides of the winding coil in the axial direction.

In addition, in order to achieve the object of the present invention, the outer stator includes an inner stator provided with an air gap spaced radially on the inner side of the outer stator, wherein the air gap is a predetermined distance along the axial direction A stator formed with a plurality of; A winding coil provided in the stator; A mover provided between the outer stator and the inner stator and provided with a mover core made of a magnetic material to reciprocate within the void; And a plurality of magnets each fixed to the inner stator so as to be respectively positioned in the plurality of voids, wherein a central core is formed at a central portion in the axial direction of the stator, and the plurality of magnets are both sides with the central core interposed therebetween A linear motor characterized in that it is fixed to may be provided.

Here, the plurality of magnets may be formed to have the same polarity in a radial direction.

In addition, the plurality of magnets may have the same length in the axial direction.

In addition, the plurality of magnets may have a length between both ends in the axial direction less than or equal to the length between both ends in the axial direction of the outer stator.

In addition, each of the plurality of magnets may be formed in an annular shape.

In addition, an annular fixing groove is formed on the outer circumferential surface of the inner stator, and a part of an annular fixing member is inserted into the fixing groove and supported in the axial direction,

In addition, at least one of the plurality of magnets may be supported in the axial direction by the fixing member.

Here, the central core may be formed by extending radially from an outer peripheral surface of the inner stator toward the outer stator.

In addition, the central core may be formed such that at least a portion of the central core overlaps the mover core in a radial direction when the mover moves.

In addition, the axial length of the central core may be formed to be less than or equal to the axial length of one magnet among the plurality of magnets.

In addition, the height of the central core in the radial direction may be lower than or equal to the height of the plurality of magnets.

Here, the central core may be formed with a predetermined spacing distance from the plurality of magnets in the axial direction.

In addition, the inner stator is made of a stator body forming a magnetic path and a central core extending from the stator body,

In addition, a support surface portion for supporting the plurality of magnets in the axial direction may be formed to be stepped at a portion where the stator body and the central core are connected.

Here, the axial length of the mover core may be formed to be longer than or equal to the axial length of the central core.

Here, the axial length of the mover core may be formed to be longer than or equal to the axial length of one magnet among the plurality of magnets.

In addition, in order to achieve the object of the present invention, a casing having an inner space; A linear motor disposed in the inner space of the casing, the mover reciprocating; A piston coupled to a mover of the linear motor to reciprocate together; A cylinder in which the piston is inserted to form a compression space; A suction valve opening and closing the suction side of the compression space; And a discharge valve that opens and closes a discharge side of the compression space, wherein the linear motor includes the linear motor described above.

Here, an elastic member for elastically supporting the piston in the axial direction of the reciprocating direction may be further provided at one side of the piston in the axial direction.

The linear motor and the linear compressor provided with the same according to the present invention, a plurality of magnets fixedly coupled to the stator, but by magnetizing the plurality of magnets in the same direction, the restoring force to the reciprocating mover core is reduced, but the thrust is reduced. It can increase the motor output. Accordingly, it is possible to reduce the amount of use of the magnet compared to the same motor output, so that when a ferrite magnet is used, a desired level of motor output can be obtained without increasing the size of the motor. In addition, when Nd magnet is used, material cost can be reduced by reducing the amount of motor used.

In addition, in the present invention, as the outer stator is provided with poles on both sides of the winding coil as the center, and the inner stator is provided with magnets on both sides with a central core interposed therebetween, the alpha waveform of the motor is based on the magnetic path center. It is formed symmetrically. Accordingly, the effective stroke section for the mover core becomes longer, so that the mover core can be more accurately controlled, thereby improving motor performance.

Further, according to the present invention, as the magnet is inserted and coupled to the outer peripheral surface of the inner stator, it is possible to facilitate the assembly operation and the magnetization operation of the magnet. Furthermore, as the plurality of magnets separated in the axial direction by the central core are magnetized in the same direction, it is possible to further facilitate the magnetizing operation on the magnet.

1 is a longitudinal sectional view showing an embodiment of a linear compressor according to the present invention,
2 is a perspective view showing a broken linear motor according to the present embodiment;
3 is a cross-sectional view taken along line "V-V" in FIG. 2;
4 is a schematic diagram as seen from the side of the linear motor according to the present embodiment;
5 and 6 are enlarged views of the "A" part of FIG. 4 shown to explain the coupling relationship between the magnet and the central core in the linear motor according to the present embodiment;
7A and 7B are schematic diagrams showing the motion of the mover according to the direction of the magnetic flux in the stator in this embodiment.
8 is a graph measuring voltage at each position during a reciprocating movement of a core in the linear motor according to the present embodiment;
9 is a graph showing the change in effective stroke according to the length of the mover core in the linear motor according to the present embodiment;
10 is a graph showing a change in an alpha value (thrust constant) during a reciprocating motion of a mover core in the linear motor according to the present embodiment.

Hereinafter, a linear compressor according to the present invention will be described in more detail with reference to the drawings. However, even in different embodiments, the same or similar reference numerals are assigned to elements that are the same or similar to those of the previous embodiment, and redundant descriptions thereof will be omitted. In addition, in describing the embodiments disclosed in the present specification, when it is determined that a detailed description of related known technologies may obscure the subject matter of the embodiments disclosed herein, the detailed description thereof will be omitted.

The accompanying drawings are only illustrated so that the embodiments disclosed in the present specification can be easily understood, and the technical spirit disclosed in the present specification is not limited by the accompanying drawings, and all changes and equivalents included in the spirit and scope of the present invention It should be understood to include water or substitutes. In addition, expressions in the singular include plural expressions unless the context clearly indicates otherwise.

The linear compressor according to the present invention includes a linear motor to suction and compress fluid, and to discharge the compressed fluid. The linear motor and the linear compressor according to the present invention may be a component of a refrigeration cycle. Hereinafter, a fluid circulating in the refrigeration cycle will be described as an example.

1 is a longitudinal sectional view showing an embodiment of a linear compressor according to the present invention. Referring to FIG. 1, the linear compressor 100 of this embodiment includes a casing 110, a frame 120, a driving unit 130, and a compression unit 140.

Casing 110 may form a closed space. The enclosed space may be a suction space 101 filled with a suctioned refrigerant. A suction port 114 is formed in the casing 110, and a suction pipe SP may be connected to the suction port 114. In addition, a discharge port 115 may be formed in the casing 110, and a discharge pipe DP may be connected to the discharge port 115.

The frame 120 may be provided inside the casing 110 to support the driving unit 130 and the compression unit 140. The frame 120 may be connected and supported to the other end of the support springs 151 and 152 positioned so that one end is fixed to the casing 110. The support springs 151 and 152 may be formed of a leaf spring, or may be formed of a coil spring.

The driving unit 130 may serve to generate a reciprocating motion of the linear compressor 100 according to the present embodiment. To this end, the driving unit 130 may include a stator 131 and a mover 132.

The stator 131 may be coupled between the frame 120 and a back cover 146 to be described later. The stator 131 may include an outer stator 1311 and an inner stator 1312. A mover 132 may be positioned between the outer stator 1311 and the inner stator 1312.

A winding coil 133 may be mounted on the outer stator 1311, and the mover 132 may include a mover core 1322 made of a magnetic material on the connection frame 1321. The mover core 1322 is not a magnet, which means a permanent magnet, and may be formed of a ferromagnetic material to form a magnetic circuit together with the stator 131 by the winding coil 133. Accordingly, in the driving unit 130 according to the present embodiment, the magnet 135, which is a permanent magnet, is coupled to the stator 131 rather than the mover 132, and the coupling structure of the magnet will be described later.

The mover 132 may include a connection frame 1321 and a mover core 1322, as described above. The connection frame 1321 may be formed of a non-magnetic metal or a resin material, and the mover core 1322 may be formed by sintering a ferromagnetic material, or may be formed by stacking a single sheet of electrical steel sheet. .

In addition, the connection frame 1321 may be formed in a cylindrical shape to be coupled to the rear end of the piston 142. Accordingly, the connection frame 1321 performs a reciprocating motion together with the piston 142.

In addition, the mover core 1322 may be formed in a single ring shape and inserted into the connection frame 1321 or may be formed in an arc shape and arranged along the circumferential direction of the connection frame 1321.

Meanwhile, the compression unit 140 sucks, compresses, and discharges the refrigerant in the suction space 101. The compression unit 140 may be located in the center of the casing 110 toward the inside of the inner stator 1312, and includes a cylinder 141 and a piston 142. The cylinder 141 is supported by the frame 120, and a compression chamber P may be formed therein.

The cylinder 141 may have a cylindrical shape to accommodate the refrigerant and the piston 142 therein, and may be formed to have both ends open. One end of the cylinder 141 may be closed by a discharge valve 1411, and a discharge cover 143 may be mounted outside the discharge valve 1411.

A discharge space 102 may be formed between the discharge valve 1411 and the discharge cover 143. That is, a space in which the compression chamber P and the discharge cover 143 are separated from each other may be formed by the discharge valve 1411. In addition, a roof pipe 144 extending so as to communicate the discharge port 115 and the discharge space 102 to each other may be installed inside the casing 110.

Meanwhile, a gas bearing 145 for lubricating between the inner peripheral surface of the cylinder 141 and the outer peripheral surface of the piston 142 may be formed by introducing a part of the refrigerant discharged into the discharge space 102 into the cylinder 141. The bearing inlet 1451 forming the inlet of the gas bearing 145 is formed through the frame 120, and the bearing passage 1452 forming the gas bearing is between the inner circumferential surface of the frame 120 and the outer circumferential surface of the cylinder 142. It is formed, and the bearing hole 1453 constituting the gas bearing may be formed to penetrate from the outer peripheral surface to the inner peripheral surface of the cylinder.

The piston 142 may be inserted into the open other end of the cylinder 141 to seal the compression chamber P. The piston 142 may be connected to the mover 132 described above and may reciprocate together with the mover 132. An inner stator 1312 and a cylinder 141 may be positioned between the mover 132 and the piston 142. Accordingly, the mover 132 and the piston 142 may be coupled to each other by a separate connection frame 1321 provided to bypass the cylinder 141 and the inner stator 1312. In the connection frame 1321, the mover core 1322 described above may be inserted and coupled to the inside or attached to and coupled to the outer surface.

The internal space of the piston 142 and the compression chamber P may be communicated with each other by the suction port 1422. That is, when the refrigerant flowing from the suction space 101 to the inner space of the piston 142 flows through the suction port 1422, and the suction valve 1421 for opening and closing the suction port 1422 is opened by the pressure of the refrigerant. The refrigerant may be sucked into the compression chamber (P).

On the other hand, the piston 142 may perform resonant motion in the axial direction (reciprocating direction) by the thrust and restoring force formed by the electromagnetic force of the linear motor, which is the drive unit 120, but as in this embodiment, the mechanical resonance spring 1471 ) (1472) can also perform a resonant motion in the axial direction. Mechanical resonance springs (hereinafter, abbreviated as resonance springs) 1471 and 1472 are formed of compression coil springs, and may be provided on both sides of the connection frame 1321 in the axial direction. In this case, the first resonance spring 1471 is provided between the connection frame 1321 and the back cover 146, and the second resonance spring 1472 is provided between the connection frame 1321 and the frame 120, respectively. I can. However, in some cases, the resonance spring may be provided only on one side of the connection frame 1321.

The linear compressor according to the present embodiment as described above operates as follows.

That is, when current is applied to the winding coil 133 constituting the driving unit 130 in a clockwise or counterclockwise direction, an alternating magnetic flux is formed in the stator 131 so that the mover 132 reciprocates in a straight line. Then, the piston 142 connected to the mover 132 increases and decreases the volume of the compression chamber P while reciprocating within the cylinder 141.

For example, when the piston 142 moves while increasing the volume of the compression chamber P, the suction stroke is performed in the compression chamber P. At this time, the internal pressure of the compression chamber (P) is reduced, the suction valve (141b) provided in the piston (142) is opened, the refrigerant remaining in the suction space (101) is sucked into the compression chamber (P).

On the other hand, when the piston 142 moves while reducing the volume of the compression chamber P, a compression stroke is performed in the compression chamber P. At this time, when the internal pressure of the compression chamber P rises and reaches a preset pressure, the discharge valve 1411 mounted on the cylinder 141 is opened to discharge the refrigerant into the discharge space 102.

As the suction and compression strokes of the piston 142 as described above are repeated, the refrigerant flows into the suction space 101 through the suction pipe (SP), and this refrigerant is sucked into the compression chamber (P) and compressed, and the discharge space A series of processes of being discharged to the outside of the compressor through 102, the loop pipe 144 and the discharge pipe DP are repeated.

On the other hand, in the linear motor and the linear compressor having the same according to the present embodiment, in order for a mover including a piston to reciprocate at high speed, the lighter the weight of the mover is, the more advantageous. However, when a magnet, which is a permanent magnet, is provided in the mover, the weight of the mover increases, and accordingly, there is a limit to moving the mover at high speed. Moreover, when a ferrite magnet having a low magnetic flux is used, the amount of magnet used increases to secure the magnetic flux, and thus, the weight of the mover is further increased, thereby reducing the efficiency of the linear motor and the linear compressor.

However, as previously explained, if an Nd magnet with a relatively high magnetic flux is used, the weight of the mover can be reduced by lowering the use of the magnet, but it is more than 10 times higher than the ferrite magnet. The manufacturing cost of motors and linear compressors can increase significantly. Therefore, in this embodiment, a relatively inexpensive magnet such as a ferrite magnet is used, but the magnet may be coupled to the stator so as to lower the weight of the mover. Accordingly, in the present embodiment, it is possible to secure the amount of magnetic flux by increasing the surface area of the magnet while lowering the material cost for the magnet.

Meanwhile, in the linear motor and the linear compressor having the same according to the present embodiment, a mechanical resonance spring made of a compression coil spring may be applied to induce a resonance motion of a mover (or piston). However, in the linear motor applied to the linear compressor of this embodiment, a certain degree of magnetic resonance spring effect occurs between the stator and the mover due to its characteristics. Accordingly, in the linear compressor, a mechanical resonance spring made of a compression coil spring is applied, so that even if a strong thrust is generated, a restoring force due to the magnetic resonance spring is generated together. Since this restoring force acts as a factor to reduce the thrust, it may be effective to lower the restoring force to increase the thrust. This can be effective in terms of controlling the reciprocating motion of the linear motor to be optimized.

That is, as described above, when a current is applied to the winding coil of the driving unit, a magnetic flux is formed in the stator, and the movable is reciprocated by the interaction of the magnetic flux formed by the current application and the magnetic flux formed by the magnet. The force to exercise can be generated. In other words, in the stator, a thrust that pushes the mover to the top dead center and the bottom dead center and a centering force that pulls the pushed mover toward the center of the magnetic path are generated. The thrust force and the restoring force are opposite forces. If the restoring force increases, the thrust may decrease, and if the restoring force increases, the thrust may decrease. In particular, from the side of a linear motor and a linear compressor equipped with a mechanical resonance spring, when the restoring force is set excessively high, the thrust that moves the mover to the top dead center and the bottom dead center decreases, and the overall motor output may be reduced.

Accordingly, in the present embodiment, a mechanical resonance spring is applied to increase the output of the motor, and at the same time, the magnet is rearranged to increase the thrust of the motor against the mover, thereby increasing the output of the motor. Here, the magnet is not necessarily limited to the ferrite series, nor is it limited that the magnet is not used at all for the mover.

2 is a broken perspective view of the linear motor according to the present embodiment, FIG. 3 is a cross-sectional view taken along line “V-V” in FIG. 2, and FIG. 4 is a schematic view seen from the side of the linear motor according to the present embodiment.

Referring back to FIG. 1, in the stator 131 according to the present embodiment, the inner stator 1312 constituting the inner core is inserted and fixed to the outer circumferential surface of the frame 120, and the outer stator 1311 constituting the outer core is It may be disposed to surround the inner stator 1312 in the circumferential direction with the set voids 1341 and 1342 interposed therebetween.

2 and 3, the outer stator 1311 and the inner stator 1312 may have both ends in the axial direction spaced apart from each other. Accordingly, air gaps 1341 and 1342 are formed between the outer stator 1311 and the inner stator 1312, which are spaces in which the mover 132 reciprocates. The voids 1341 and 1342 are formed on both sides in the axial direction with between the winding coils 133 to be described later. Here, the axial direction is the direction in which the mover reciprocates.

4, the stator 131 is composed of an outer stator 1311 and an inner stator 1312, as described above, and the outer stator 1311 and the inner stator 1312 are spaced apart from each other in the radial direction by a gap. do.

The outer stator 1311 may be formed in a cylindrical shape by radially stacking a stator sheet (unsigned) in a single sheet, or a plurality of stator sheets formed by stacking a stator sheet in a thickness direction as shown in Figs. Stator blocks (unsigned) may be radially stacked to form a cylindrical shape. The inner stator 1312 may be formed in a cylindrical shape by radially stacking a stator sheet made of a sheet.

The outer stator 1311 may be formed in a'∩' shape by seating the winding coil 133 in the middle of the axial direction, and the inner stator 1312 may be formed in a'-' shape long in the axial direction. Accordingly, the outer stator 1311 may have a winding coil groove 133a formed in the middle, and gaps 1341 and 1342 described above may be formed on both sides of the winding coil groove 133a, respectively.

And the outer stator 1311 is connected to both ends of the outer axial yoke portion 1311a and the outer axial yoke portion 1311a forming the outer circumferential surface of the winding coil groove 133a, and both sides in the axial direction of the winding coil groove 133a A plurality of radial yoke portions (hereinafter, a first radial yoke portion and a second radial yoke portion) 1311b and 1311c may be formed.

The outer axial yoke portion 1311a is formed to be long in the axial direction (moving direction or reciprocating direction of the mover), so that the axial length L11 of the outer axial yoke portion 1311a is radial (with respect to the moving direction of the mover). Orthogonal direction) is formed longer than the length (L12). The first radial yoke portion 1311b and the second radial yoke portion 1311c are formed to be elongated in the radial direction, so that the radial length L13 may be longer than the axial length L14.

And the radial length (L12) of the outer axial yoke portion (1311a) is formed approximately the same as the axial length (L14) of the first radial yoke portion (1311b) or the second radial yoke portion (1311c), The axial length L14 of the first radial yoke portion 1311b or the second radial yoke portion 1311c may be formed to be smaller than the axial length L15 of the winding coil groove 133a. The first radial yoke portion 1311b and the second radial yoke portion 1311c may be symmetrically formed with respect to the coil winding groove 133a.

On the other hand, a polarity first pawl portion 1311d and a second pawl portion 1311e formed by extending polarity may be formed at each inner circumferential end of the first radial yoke portion 1311b and the second radial yoke portion 1311c. have. In other words, the first pawl portion 1311d may be extended to the first radial yoke portion 1311b, and the second pawl portion 1311e may be extended to the second radial yoke portion 1311c.

The first pawl portion 1311d is formed to extend in the axial direction toward the magnetic path center Cm from the inner circumferential end of the first radial yoke portion 1311b, and the second pawl portion 1311e is a second radial yoke portion ( 1311c) may be formed to extend in the axial direction toward the magnetic path center Cm at the inner circumferential end thereof. Accordingly, the first pawl portion 1311d and the second pawl portion 1311e are formed to extend in a direction toward each other to be close, and a stator airgap between the first pawl portion 1311d and the second pawl portion 1311e ) (1311f) is formed to be spaced apart.

The center of the stator void 1311f is formed in the axial center of the stator 131, that is, the magnetic path center (Cm) so as to face the central core 1312b, which will be described later, in the radial direction when the motor (or compressor) is stopped. Can be. Further, the axial length L16 of the stator void 1311f may be formed to be shorter than the axial length L28 of the central core 1312b.

Meanwhile, as described above, the inner stator 1312 may be formed in a cylindrical shape by radially stacking a sheet of stator sheets.

In addition, the inner stator 1312 may include an inner axial yoke portion 1312a forming a magnetic path, and a central core 1312b protruding from the center of the inner axial yoke portion 1312a toward the outer stator 1311. . Accordingly, the inner circumferential surface of the inner stator 1312 may be formed to have the same diameter along the axial direction, while the outer circumferential surface may be formed to have a different diameter along the axial direction. In other words, the inner circumferential surface of the inner stator 1312 is formed with a single diameter so as to be in close contact with the outer circumferential surface of the frame 120, while the outer circumferential surface is formed so that the central core 1312b described above protrudes toward the outer stator 1311 to be stepped. I can.

The axial length L21 of the inner axial yoke portion 1312a may be formed to be at least equal to or longer than the axial length L11 of the outer stator 1311. Accordingly, the length L22 between both ends in the axial direction of the first magnet 1351 and the second magnet 1352 to be described later is the length between both ends in the axial direction of the first pole part 1311d and the second pole part 1311e ( L17) may be formed longer than or equal to.

In addition, the radial length (thickness) L23 of the inner axial yoke portion 1312a is formed to be greater than or equal to the radial length L12 of the outer axial yoke portion 1311a. It can be advantageous to magnify.

Meanwhile, the central core 1312b may be formed in a rectangular shape. However, the outer ends of the central core 1312b may have both edges inclined or stepped.

Further, the inner end of the central core 1312b may extend stepwise from the inner axial yoke portion 1312a. For example, as shown in FIG. 5, support surface portions 1312b1 may be formed stepped on both sides of the central core 1312b in the axial direction. Accordingly, a portion of the side surfaces of the magnets 1351 and 1352 facing the central core 1312b may be in close contact with the support surface portion 1312b1 in the axial direction while being spaced apart from the central core 1312b.

However, as shown in FIG. 6, both sides in the axial direction of the central core 1312b are formed as a single straight surface, so that the side surfaces of the magnets 1351 and 1352 facing the central core 1312b are axially aligned with the central core 1312b. Can be tightly attached. Accordingly, it is possible to increase the axial support force for the magnets 1351 and 1352.

In addition, a first magnet 1351 and a second magnet 1352 may be coupled to both sides of the central core 1312b in the axial direction, respectively. Accordingly, the first magnet 1351 and the second magnet 1352 are disposed to be spaced apart from each other with the central core 1312b interposed therebetween.

In addition, the axial side of the central core 1312b may be in contact with the magnets 1351 and 352, but as described above, both magnets 1351 and 1352 are provided with a support surface portion 1312b1 on the central core 1312b. ) And the separation distance (L24) spaced apart in the axial direction may be formed. Accordingly, the central core 1312b can firmly support one side of the magnets 1351 and 1352 in the axial direction while being spaced apart from both magnets 1351 and 1352. In addition, as a part of the central core 1312b is separated from the magnets 1351 and 1352, it is possible to suppress the magnetization of the central core 1312b when the magnets 1351 and 1352 are magnetized. The separation distance L24 between the central core 1312b and the magnets 1351 and 1352 may be formed to be approximately 20 to 30% of the thickness L25 of the magnet.

In addition, the height L26 of the central core 1312b may be formed to be lower than or equal to the height (radial thickness) L25 of the first magnet 1351 and the second magnet 1352. However, since the central core 1312b forms a passage connecting a kind of magnetic path, it may be formed higher than the height L25 of the magnet within a range not in contact with the mover core 1322 to be described later. However, since the sizes of the first and second pores 1341 and 1342 are defined by the height L25 of the magnet, the central core 1312b is usually not formed higher than the magnets 1351 and 1352. .

In addition, it may be preferable that the central core 1312b be formed to have a length such that it may overlap with the mover core 1322 in the radial direction. Thereby, the effective stroke range of the mover core 1322 can be formed wide.

In addition, the axial length of the central core 1312b may be formed to be less than or equal to the axial length L27 of one magnet among the plurality of magnets 1351 and 1352. For example, if the axial length (L28) of the central core is formed longer than the axial length (L27) of the magnet, the axial length (L27) of the magnet becomes shorter, so the magnetic flux density due to the characteristics of a ferrite magnet with a low magnetic flux Is further lowered and motor performance may be degraded. Accordingly, the axial length L28 of the central core may be formed to be less than or equal to the axial length L27 of the magnet. For example, it may be desirable to be formed such that the axial length L28 of the central core is approximately 50 to 70% of the axial length L27 of the magnet.

Meanwhile, the first magnet 1351 and the second magnet 1352 may be formed in an annular shape or may be formed in an arc shape. When the magnets 1351 and 1352 are formed in an annular shape, they can be inserted into and coupled to the outer peripheral surface of the inner stator 1312, and when formed in an arc shape, they can be attached and coupled to the outer peripheral surface of the inner stator 1312. . Accordingly, as the magnets 1351 and 1352 are inserted and coupled to the outer circumferential surface of the inner stator 1312, it is possible to facilitate the assembly work and magnetization work of the magnets 1351 and 1352. In particular, in the case where the magnets 1351 and 1352 are formed in an annular shape, the magnets 1351 and 1352 can be press-fitted to the outer peripheral surface of the inner stator 1312 to be coupled, making it easier to assemble the magnet. .

Further, by magnetizing the first magnet 1351 and the second magnet 1352 spaced apart in the axial direction by the central core 1312b in the same direction, it is possible to further facilitate the magnetization operation on the magnet.

In addition, after the first magnet 1351 and the second magnet 1352 are coupled to the inner stator 1312, they may be supported so as not to deviate in the axial direction. For example, as shown in Figure 2, the direction toward the central core (1312b) is supported in close contact with the support surface portion (1312b1) provided on both sides of the central core (1312b) or both sides of the central core (1312b), The opposite direction may be supported in the axial direction by each fixing member 1315 coupled to the inner stator 1312. The fixing member 1315 is formed in a C-ring shape, and annular fixing grooves 1315a are respectively formed on the outer circumferential surfaces of both ends of the inner stator 1312, and each fixing member 1315 is each fixed groove ( 1315a) is inserted and joined.

In addition, as shown in FIG. 4, the first magnet 1351 and the second magnet 1352 may be magnetized in the same direction. Accordingly, the first magnet 1351 and the second magnet 1352 have the same polarity in the radial direction. For example, the first magnet 1351 and the second magnet 1352 have an inner circumferential surface of the first magnet 1351 and an inner circumferential surface of the second magnet 1352 so that a line of magnetic force can be formed from an inner circumferential surface to an outer circumferential surface. , The outer peripheral surface can be magnetized to the S pole. Accordingly, by removing or minimizing the restoring force for the mover core 1322 around the first magnet 1351 and the second magnet 1352, only the thrust force for the mover core can be generated or maximized. This will be described later.

In addition, the first magnet 1351 and the second magnet 1352 may have the same axial length L27. Accordingly, the mover core 1322 reciprocates by the same distance from the magnetic path center Cm.

However, in some cases, the axial length L27 of the first magnet 1351 and the axial length L27 of the second magnet 1352 may be formed differently. For example, when the linear motor is applied to a linear compressor having one compression chamber, the second magnet 1352 close to the compression chamber P considering that the piston 142 is pushed by the pressure in the compression chamber P. ) Of the axial length (L27) may be formed longer than the axial length (L27) of the first magnet (1351). Alternatively, the second magnet 1352 may be disposed closer to the compression chamber based on the magnetic path center Cm. Accordingly, the piston connected to the mover core may generate a greater thrust toward the compression chamber.

In addition, the axial length of the magnet, which is the sum of the axial length of the first magnet 1351 and the axial length of the second magnet 1352, is the axial length of the first pole part 1311d and the axial length of the second pole part 1311e. It may be formed to be less than or equal to the axial length of the outer stator 1311 in which direction lengths are summed. For example, the length L22 from the end in the bottom dead center direction of the first magnet 1351 to the end in the top dead center direction of the second magnet 1352 is the second pole part at the end in the bottom dead center direction of the first pole part 1311d ( It may be formed to be less than or equal to the length L17 of 1311e) to the end in the top dead center direction. Accordingly, leakage of magnetic flux passing through the first magnet 1351 and the second magnet 1352 is minimized, thereby increasing motor efficiency.

On the other hand, the mover core 1322, as described above, is not a magnet that means a permanent magnet, and it is sufficient if it is a magnetic material capable of forming a magnetic circuit together with the stator 131 by the winding coil 133 like an electrical steel sheet. .

In addition, the axial length of the mover core 1322 may be formed to be longer than or equal to the axial length of one magnet among the plurality of magnets 1351 and 1352. In addition, the axial length L31 of the mover core 1322 may be formed to be shorter than the sum of the axial lengths of the plurality of magnets. Accordingly, the mover core 1322 performs a reciprocating motion according to the direction of the magnetic flux formed in the stator 1311. However, the starting point and the ending point of the effective stroke are changed according to the axial length L31 of the mover core 1322 and the alpha value is also changed. For example, the shorter the axial length L31 of the mover core 1322 is, the narrower the effective stroke range, while the longer the axial length L31 of the mover core 1322 is, the greater the effective stroke range. It becomes wider. This will be described later with reference to FIG. 9.

In the linear motor according to the present embodiment as described above, the mover reciprocates according to the direction of the magnetic flux formed in the stator. 7A and 7B are schematic diagrams showing the motion of the mover according to the direction of magnetic flux in the stator according to the present embodiment.

7A shows that the magnetic flux is formed in a clockwise direction, in this case, the mover 1322 moves in the direction of the bottom dead center, which is the right side of the drawing. At this time, the magnetic flux formed in the outer stator 1311 moves to the central core 1312b through the outer axial yoke portion 1311a, the first radial yoke portion 1311b, and the first pawl portion 1311d. Among the magnetic fluxes moving to the central core 1312b, a relatively large amount of magnetic flux is sucked into the inner polarity (N pole) of the first magnet 1351. This magnetic flux moves to the polarity (S pole) of the outer surface of the first magnet 1351 and then returns to the central core 1312b through the mover core 1322 while forming a closed loop with respect to the mover core 1322. Increases thrust. Accordingly, the mover core 1322 moves from the stator center defined as the magnetic path center Cm to the bottom dead center, which is far from the right direction of the drawing.

7B shows that the magnetic flux is formed in a counterclockwise direction, in this case, the mover 1322 moves in the top dead center direction on the left side of the drawing. At this time, the magnetic flux formed in the outer stator 1311 moves to the central core 1312b through the outer axial yoke portion 1311a, the second radial yoke portion 1311c, and the second pawl portion 1311e. Among the magnetic fluxes moving to the central core 1312b, a relatively large amount of magnetic flux is attracted to the inner polarity (N pole) of the second magnet 1352. This magnetic flux moves to the polarity (S pole) of the outer surface of the second magnet 1352 and then returns to the central core 1312b through the mover core 1322 while forming a closed loop with respect to the mover core 1322. Increases thrust. Accordingly, the mover core 1322 moves from the stator center defined as the magnetic path center Cm to the top dead center, which is far from the left direction of the drawing.

Here, as shown in FIGS. 7A and 7B, magnetic fluxes are formed in the first magnet 1351 and the second magnet 1352 from an inner circumferential surface to an outer circumferential surface, respectively. Accordingly, the first pole part 1311d of the outer stator 1311 and the first magnet (and one end of the inner stator) 1351 facing it, the second pole part 1311e and the second magnet facing it (and the inner stator) The eddy magnetic flux is not formed or is formed very weakly between the other end of (1352). Then, the centering force on the mover core 1322 moved to the bottom dead center or the mover core 1322 moved to the top dead center is weakly generated, so that the mover core 1322 is at the bottom dead center as described above. Or it will be able to move smoothly to the top dead center. That is, while the restoring force for the mover core 1322 decreases, the thrust increases, so that the motor output compared to the surface area of the same magnet may be improved. Conversely, it is possible to reduce the amount of magnet used compared to the same motor output, and thus, when using a ferrite magnet, a desired level of motor power can be obtained without increasing the size of the motor. In addition, when Nd magnet is used, material cost can be reduced by reducing the amount of use of the motor.

Meanwhile, as described above, in this embodiment, the mover core 1322 can be smoothly moved to the top dead center or the bottom dead center, so that the control characteristics for the mover core 1322 can be improved.

In general, when controlling the mover core 1322 based on the bottom dead center, a voltage of a substantially similar degree is applied for a predetermined time in the bottom dead center section. This section is defined as a controllable section, that is, an effective stroke section. 8 is a graph measuring voltage at each position during a reciprocating movement of a core in the linear motor according to the present embodiment. Referring to this, the effective stroke range of the mover can be known.

Referring to FIG. 8, the effective stroke section is a section between approximately 0.005 seconds to 0.015 seconds. It can be seen that even when compared with Patent Document 1 as well as Patent Document 2, the effective stroke range at the bottom dead center was expanded. This is because, as described above, as the first magnet 1351 and the second magnet 1352 are magnetized in the same direction, the eddy magnetic flux is not formed or is formed very low.

In addition, in the present embodiment, a first pole part 1311d and a second pole part 1311e are provided on both sides of the winding coil, and the first magnet 1351 and the second magnet 1352 are located on the central core 1312b. Are spaced apart from each other by Accordingly, the alpha waveform of the motor is formed symmetrically with respect to the magnetic path center, so that the effective stroke section is lengthened. Then, the mover core 1322 can be more accurately controlled, thereby improving motor performance. At this time, the effective stroke range may appear differently according to design variables such as the height (thickness) of the central core 1312b and the length of the mover core 1322.

For example, when the length of the mover core 1322 is short, the effective stroke range decreases, and when the length of the mover core 1322 increases, the effective stroke range increases. 9 is a graph showing a change in an effective stroke according to the length of a mover core in the linear motor according to the present embodiment.

In this experiment, the height of the central core 1312b for each model was the same and the length of the mover core 1322 was set differently. That is, the model ① has the shortest length of the mover core 1322, and increases the length of the mover core 1322 in the order of model ②, model ③, and model ④. The length of the mover core 1322 of the model ④ is the longest.

Referring to FIG. 9, the voltage in the bottom dead center section is the highest in the model ① and the lowest in the model ④. Also, as for the effective stroke section, model ① is the narrowest and model ④ is the widest. It can be seen that the longer the length of the mover core 1322 is, the longer the overlapping section between the mover core 1322 and the central core 1312b increases, thereby increasing the range of the effective stroke. Accordingly, in order to increase the range of the effective stroke, the length of the mover core 1322 is formed as long as possible, but at least a part of the mover core 1322 at the top dead center or the bottom dead center is radially aligned with the central core 1312b. It can be seen that it is advantageous to be formed so as to be able to overlap.

It is also related to the shape of the motor. For example, the linear motor according to the present embodiment forms a two-gap motor in which voids 1341 and 1342 are formed on both sides of the winding coil 133 as the center. Accordingly, the alpha value defined as the thrust constant is symmetrical compared to that of a single-gap motor. Then, the mover core 1322 moves from bottom dead center to top dead center and from top dead center to bottom dead center to form a shape similar to each other, thereby increasing the effective stroke range for the mover core 1322. The efficiency of can be improved. 10 is a graph showing a change in an alpha value (thrust constant) during a reciprocating motion of a mover core in the linear motor according to the present embodiment. This is a graph showing the alpha value when the inner diameter of the magnet is 26mm, the outer diameter of the magnet is 30mm, the length of the magnet is 20mm, and the weight of the mover core is 141g. Since the X-axis of this graph represents the time for the reciprocating motion of the mover core, the position of the mover core is displayed, and the Y-axis represents the voltage at the corresponding position, and thus the alpha value at the corresponding position is displayed.

As shown, the alpha value of the two-gap linear motor according to the present embodiment shows a peak value of 42.15 at a point where the mover core is slightly inclined from the magnetic path center (0.01 point) to the bottom dead center, and a peak value of 42.15 is shown. It shows 42.01 similar to the peak value at 0.012 point, which is slightly biased.

Through the graph shown in FIG. 10, it can be seen that the movement of the mover core 1322 from the bottom dead center to the top dead center and the movement from the top dead center to the bottom dead center are substantially symmetrical. Through this, a range of a controllable stroke for the mover core 1322 is widened, thereby simplifying control of the mover core 1322, thereby improving motor efficiency. Moreover, the efficiency of a linear compressor employing this linear motor can also be improved.

On the other hand, in the above, the linear motor has been described as an example. Therefore, if the linear motor described above is applied to the linear compressor, the same effect obtained from the linear motor can be expected in the linear compressor. Therefore, the description of the linear motor applies mutatis mutandis to the linear compressor.

Claims (16)

An outer stator, and an inner stator provided with an air gap spaced apart in a radial direction inside the outer stator, wherein a plurality of stators are formed at predetermined intervals along the axial direction;
A winding coil provided in the stator;
A mover provided between the outer stator and the inner stator and provided with a mover core made of a magnetic material to reciprocate within the void; And
Includes; a plurality of magnets each fixed to the inner stator so as to be respectively positioned in the plurality of voids,
The outer stator includes a first pole part and a second pole part that are disposed on both sides of the winding coil in the axial direction and have a stator gap formed therebetween,
A central core is formed in an axial central portion on the outer peripheral surface of the inner stator,
The plurality of magnets are disposed to face each of the first and second poles and are fixed to both sides with the central core interposed therebetween,
The linear motor, characterized in that the plurality of magnets have the same polarity in the radial direction so as to be magnetized in the same direction. delete The method of claim 1,
Linear motor, characterized in that the plurality of magnets have the same axial length. The method of claim 3,
The plurality of magnets are linear motors, characterized in that the length between both ends in the axial direction is formed to be less than or equal to the length between both ends in the axial direction of the outer stator. The method of claim 4,
The plurality of magnets are linear motors, characterized in that each formed in an annular shape. The method of claim 5,
An annular fixing groove is formed on the outer peripheral surface of the inner stator, and a part of an annular fixing member is inserted into the fixing groove and supported in the axial direction,
A linear motor, characterized in that at least one of the plurality of magnets is supported in the axial direction by the fixing member. The method of claim 1,
The central core is a linear motor, characterized in that extending in a radial direction toward the outer stator from the outer peripheral surface of the inner stator. The method of claim 7,
The central core is a linear motor, characterized in that formed such that at least a portion of the central core overlaps the mover core in a radial direction when the mover moves. The method of claim 8,
The linear motor, characterized in that the axial length of the central core is formed to be less than or equal to the axial length of one of the plurality of magnets. The method of claim 8,
The linear motor, characterized in that the radial height of the central core is formed equal to or lower than the heights of the plurality of magnets. The method of claim 1,
The central core is a linear motor, characterized in that formed with a predetermined separation distance in the axial direction and the plurality of magnets. The method of claim 11,
The inner stator is made of a stator body forming a magnetic path and a central core extending from the stator body,
A linear motor, characterized in that a support surface portion for supporting the plurality of magnets in an axial direction is formed to be stepped at a portion where the stator body and the central core are connected. The method of claim 1,
Linear motor, characterized in that the axial length of the mover core is formed to be longer than or equal to the axial length of the central core. The method of claim 1,
The linear motor, wherein the axial length of the mover core is formed to be longer than or equal to the axial length of one magnet among the plurality of magnets. A casing having an inner space;
A linear motor disposed in the inner space of the casing, the mover reciprocating;
A piston coupled to a mover of the linear motor to reciprocate together;
A cylinder in which the piston is inserted to form a compression space;
A suction valve opening and closing the suction side of the compression space; And
Includes; a discharge valve for opening and closing the discharge side of the compression space,
The linear motor is a linear compressor, characterized in that the linear motor of any one of claims 1, 3 to 14. The method of claim 15,
Linear compressor, characterized in that further provided with an elastic member elastically supporting the piston in the axial direction of the reciprocating direction on one side of the axial direction of the piston.

Images