CN102804567A - Linear motor - Google Patents

Abstract

Provided is a linear motor, wherein the dimension of a base section of magnets can be suppressed from becoming larger, even when the dimension of the magnets, along a straight line that is perpendicular to the direction the magnets are lined up, and that is parallel to an opposing face of an armature-core facing the magnets, is made to be larger than the dimension of the armature-core along this straight line. The linear motor is provided with: a field system (1) that is equipped with the base section (3), and multiple magnets (4) lined-up on this base section (3); and an armature (2) that is equipped with the armature-core (5) that faces the magnets (4), and that moves along the direction in which the magnets (4) are lined up. The whole area of the opposing face of the armature-core (5) faces the magnets (4), when viewed along the direction in which the magnets (4) are lined up; and each of the magnets (4) adjacent to each other have the centers thereof deviate from the center of the armature-core (5), in mutually different directions; and mounting holes (3a) are formed on the base section (3), at areas located in directions opposite the deviating directions of the magnets (4), when viewed along a direction perpendicular to the opposing face (5a).

Description

linear motor

technical field

The present invention relates to a linear motor having an exciter and an armature facing the exciter.

Background technique

At present, a linear motor is known, which has: an excitation part having a plate-shaped base and a plurality of magnets juxtaposed with the base; The opposing armature core and the coil provided on the armature core move in the direction in which the magnets are aligned (for example, refer to Patent Document 1).

On the base, a plurality of mounting holes are formed along the direction in which the magnets are juxtaposed on both end parts along a straight line perpendicular to the direction in which the magnets are juxtaposed and parallel to the facing surface of the armature core facing the magnets . Fastening bolts are passed through these mounting holes, and the excitation part is mounted on the supporting member.

prior art literature

Patent Document 1: Japanese PCT Publication No. 2000-501274

In order to increase the amount of magnetic flux emanating from the magnet and interlinking with the armature core, it is considered that the size of the magnet along the line is larger than the size of the armature core along the line. direction and parallel to the opposite face of the armature core opposite the magnet.

However, in this case, in order to make the size of the magnet along the line perpendicular to the direction in which the magnets are arranged larger than the size of the armature core along the line, it is necessary to increase the size between the mounting holes along the line. And parallel to the opposite face of the armature core opposite to the magnet.

As a result, the size of the base portion along the straight line becomes large, and there is a problem of increasing the size of the linear motor.

Contents of the invention

The present invention provides a linear motor capable of increasing the amount of magnetic flux from a magnet interlinked with an armature core while suppressing increase in size.

The linear motor of the present invention has: an excitation part having a base and a plurality of magnets arranged in parallel on the base; The coil on the core, and moves relative to the excitation part along the direction in which the magnets are juxtaposed, and when viewed along the direction in which the magnets are juxtaposed, the entire area of the opposite surface of the armature core that is opposite to the magnet is in line with the The magnets face each other, and when viewed in a direction perpendicular to the facing surface, some of the plurality of magnets are staggered in one direction relative to the armature core along a straight line intersecting in a direction parallel to the magnets, and one end protrudes from the armature core, the remaining magnets are offset relative to the armature core in a direction opposite to the one direction and one end protrudes from the armature core, on the base, A mounting hole is formed in a region away from the magnet in a direction opposite to the shifting direction of the magnet.

The effect of the invention

In the linear motor of the present invention, when viewed along the direction in which the magnets are aligned, the entire area of the facing surface of the armature core faces the magnet, and when viewed along a direction perpendicular to the facing surface of the armature core facing the magnet, the plurality of magnets A part of them is staggered in one direction relative to the armature core along a straight line intersecting with respect to the parallel direction of the magnets and one end protrudes from the armature core, and the remaining magnets are staggered in the opposite direction of one direction relative to the armature core and One end protrudes from the armature core, and on the base, a mounting hole is formed in a region away from the magnet in a direction opposite to the direction in which the magnet is staggered, so that the size of the magnet along the line is larger than that along the line The size of the armature core is large, wherein the above-mentioned straight line is perpendicular to the direction in which the magnets are juxtaposed and parallel to the opposite face of the armature core facing the magnet, so that the magnetic flux from the magnet interlinked with the armature core can be In addition, the size of the base can be suppressed from increasing, and the increase in size of the linear motor can be suppressed.

Description of drawings

FIG. 1 is a plan view showing a linear motor according to Embodiment 1 of the present invention.

Fig. 2 is a front view showing the linear motor of Fig. 1 .

Fig. 3 is a side view showing a principal part of the linear motor in the case where the size of the magnet and the size of the armature core are equal along the direction A of Fig. 1 .

Fig. 4 is a side view showing essential parts of the linear motor of Fig. 1 .

5 is a plan view showing a modified example of the linear motor according to Embodiment 1 of the present invention.

6 is a plan view showing a linear motor according to Embodiment 2 of the present invention.

7 is a graph showing the rate of increase of the back electromotive force of the linear motor according to Embodiment 3 of the present invention.

8 is a plan view showing a linear motor according to Embodiment 4 of the present invention.

9 is a perspective view showing a linear motor according to Embodiment 5 of the present invention.

Fig. 10 is a sectional view taken along the line X-X in Fig. 9 .

FIG. 11 is a perspective view showing a linear motor in a case where opposing magnets in FIG. 9 are shifted in the same direction along the A direction.

Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11 .

FIG. 13 is a plan view showing an excitation portion of a linear motor according to Embodiment 6 of the present invention.

Detailed ways

Hereinafter, each embodiment of the present invention will be described based on the drawings, but the same or corresponding members and locations will be described with the same reference numerals in each of the drawings.

Embodiment 1

FIG. 1 is a plan view showing the linear motor of this embodiment, and FIG. 2 is a front view showing the linear motor of FIG. 1 .

The linear motor of the present embodiment has an exciting part 1 and an armature 2 facing the exciting part 1 .

The excitation unit 1 has a flat plate-shaped base 3 and a plurality of magnets 4 arranged on the base 3 at regular intervals along a line. All the magnets 4 are formed in the same rectangular parallelepiped shape.

The armature 2 has an armature core 5 facing the magnet 4 and a coil 6 provided on the armature core 5 .

The armature 2 is supported by a guide device (not shown) that guides the armature 2 in the direction in which the magnets 4 are aligned while maintaining the distance between the armature 2 and the field part 1 at a predetermined gap length.

Armature core 5 is magnetized by energization of coil 6 . The armature 2 moves relative to the excitation unit 1 in the direction in which the magnets 4 are aligned by utilizing the magnetic force generated between the armature core 5 and the magnet 4 .

The base 3 is made of iron. In addition, the base 3 is not limited to iron, as long as it is a material that can be magnetized by a surrounding magnetic field.

The magnets 4 are arranged such that adjacent magnetic poles are different from each other.

In this embodiment, a direction along a straight line that is perpendicular to the direction in which the magnets 4 are aligned, that is, the moving direction of the armature 2 and parallel to the opposing surface of the armature core 5 facing the magnets 4 is defined as the A direction. 5a straight line. In addition, the same applies to other embodiments.

The longitudinal direction of each magnet 4 is along the A direction. A dimension L2 of each magnet 4 along the A direction is larger than a dimension L1 of the armature core 5 along the A direction.

Adjacent magnets 4 are shifted by the same amount in opposite directions in direction A relative to armature core 5 when viewed in a direction perpendicular to opposing surface 5 a. In addition, the amount of offset between adjacent magnets 4 may be different.

Since the magnets 4 are shifted by the same amount from the armature core 5 , one end 4 a of each magnet 4 protrudes uniformly in the direction A from the armature core 5 when viewed in a direction perpendicular to the facing surface 5 a. In addition, the one end 4a of each magnet 4 is not limited to protruding in the direction A, and when viewed from a direction perpendicular to the facing surface 5a of the armature core 5, it can be viewed from the armature core 5 along a straight line intersecting with the direction in which the magnets 4 are arranged. Just stand out.

The other end portion 4b of each magnet 4 and the end portion of the armature core 5 along the direction A are on the same straight line along the direction in which the magnets 4 are arranged when viewed in a direction perpendicular to the facing surface 5a.

Therefore, the entire region of the facing surface 5 a of the armature core 5 faces the magnets 4 when viewed along the direction in which the magnets 4 are aligned.

In addition, the other end portion 4b of each magnet 4 may protrude from the armature core 5 when viewed in a direction perpendicular to the facing surface 5a. However, in this case, the amount of protrusion of the other end portion 4b is smaller than the amount of protrusion of the one end portion 4a.

In the base 3, a plurality of mounting holes 3a through which fastening bolts (not shown) are inserted are formed so as to avoid the respective magnets 4. As shown in FIG. The excitation unit 1 is attached to a support member (not shown) by fastening bolts inserted into the attachment holes 3a.

The mounting hole 3 a is formed in a region of the base 3 away from the magnet 4 in a direction opposite to the shifting direction of the magnet 4 when viewed in a direction perpendicular to the facing surface 5 a. A part of the mounting hole 3a enters the inside of the base 3 in the A direction compared with a straight line passing between the protruding end portions 4a of the respective magnets 4 when viewed in a direction perpendicular to the facing surface 5a.

Thus, regardless of whether the dimension L2 of the magnet 4 along the A direction is larger than the dimension L1 of the armature core 5 along the A direction, the dimension L3 between the mounting holes 3 a along the A direction can be suppressed from increasing.

Next, the effect of making the dimension L2 of the magnet 4 along the A direction larger than the dimension L1 of the armature core 5 along the A direction will be described.

3 is a side view showing key parts of the linear motor when the dimension L2 of the magnet 4 and the size L1 of the armature core 5 are equal in the direction A, and FIG. 4 is a side view showing key parts of the linear motor shown in FIG. 1 .

In the case where the dimension L2 of the magnet 4 and the dimension L1 of the armature core 5 are equal in the direction A, the magnetic flux from the area of the magnet 4 opposite to the end of the armature core 5 does not intersect with the armature core 5. Chain ground to base 3.

On the other hand, in the linear motor of this embodiment, the magnetic flux from the region of the magnet 4 facing the end of the armature core 5 interlinks with the armature core 5, and the magnetic flux interlinked with the armature core 5 The amount of magnetic flux increases.

As a result, the counter electromotive force generated in the coil 6 can be increased.

Next, the maximum deflection D generated in the base portion 3 of the linear motor of this embodiment will be described.

Between the excitation part 1 and the armature 2, there is an attractive force through magnetic interaction. As a result, the middle portion in the direction A of the base portion 3 flexes toward the armature 2 .

Considering only the area where the field part 1 and the armature 2 face each other, the attractive force acting between the field part 1 and the armature 2 applies a load substantially uniformly over the entire range between the mounting holes 3a along the direction A. Therefore, The maximum deflection D of the base portion 3 is calculated by the following formula (1).

D∝(w×L34)/(384×E×I) (1)

Here, w is the load per unit length, E is the longitudinal elastic coefficient of the base 3, and I is the section moment of inertia.

In addition, w is the conversion value per unit length of the attraction|suction force which acts between the field part 1 and the armature 2, and gravity. In addition, E is a coefficient determined by the material of the base 3 .

In the above formula (1), I is determined by the cross-sectional shape of the base 3, and in the case of a rectangular cross-section, it is calculated by the following formula (2) using the thickness h and width b of the base 3 .

I＝(1/12)×b×h3 (2)

By substituting the above formula (2) into the above formula (1), the following formula (3) is obtained.

D∝(w×L34)/(384×E×b×h3) (3)

It can be seen from the above formula (3) that the larger L3 is, the larger the maximum deflection D is. It is considered that as the maximum deflection D increases, the field part 1 and the armature 2 will rub against each other, and at least one of the field part 1 and the armature 2 will be damaged.

In the conventional linear motor, since the dimension L3 between the mounting holes 3 a along the direction A becomes large, it is necessary to increase the thickness h of the base 3 in order to suppress an increase in the maximum deflection D.

Therefore, in the conventional linear motor, the field part 1 is enlarged, and the weight of the linear motor becomes large.

On the other hand, in the linear motor of this embodiment, since the dimension L3 between the mounting holes 3a along the A direction can be suppressed from increasing, even when the thickness h of the base 3 is reduced, it can be designed to be different from the conventional one. The maximum deflection D of the linear motor is approximately equal.

Specifically, in the conventional linear motor, when L3 = 50 mm and h = 10 mm, in the linear motor of this embodiment, when L3 = 40 mm, when h = 7.4 mm, it is different from the conventional linear motor. The base 3 of the linear motor has approximately equal maximum deflection D.

In this way, since the thickness h of the base portion 3 can be reduced, the space for installing the linear motor can be reduced in size, and the weight of the linear motor can be reduced.

As described above, according to the linear motor of this embodiment, when viewed in a direction perpendicular to the facing surface 5a, some of the plurality of magnets 4 are shifted in the direction A with respect to the armature core 5, and one end 4a is separated from the armature core 5a. 5 protrudes, and the remaining magnets are staggered in the opposite direction to the A direction relative to the armature core 5, and one end 4a protrudes from the armature core 5, and on the base 3, moves away in the direction opposite to the staggering direction of the magnet 4. The region of the magnet 4 is formed with a mounting hole 3a, therefore, the dimension L2 of the magnet 4 along the A direction is larger than the dimension L1 of the armature core 5 along the A direction, and the magnets interlinked with the armature core 5 can be made larger. The amount of the magnetic flux of 4 increases, and the size L3 of the base 3 can be suppressed from increasing, thereby suppressing an increase in the size of the linear motor.

In addition, when the base 3 is plate-shaped, since the dimension L3 between the mounting holes 3a along the A direction can be suppressed from increasing, it is not necessary to reduce the maximum deflection D of the base 3, and as a result, the thickness h of the base 3 can be suppressed. get bigger.

In addition, since the shifting directions of the magnets 4 adjacent to each other are opposite to each other, the mounting holes 3 a can be arranged near the magnets 4 along the moving direction of the magnets 4 .

As a result, the mounting holes 3 a can be formed at equal intervals along the moving direction of the armature 2 . In addition, a large number of mounting holes 3 a can be formed.

In addition, when viewed from a direction perpendicular to the opposing surface 5a, the other end portion 4b of the magnet 4 and the end portion of the armature core 5 along the direction A are on the same straight line along the direction in which the magnets 4 are arranged, so that The dimension L3 between the mounting holes 3 a in the direction A is the smallest.

In addition, in this embodiment, the linear motor in which the dimension of the field part 1 along the direction in which the magnets 4 are arranged is larger than the dimension of the armature 2 along the same direction has been described, but it is not limited to this, and the field part 1 may be A linear motor in which the dimension along the direction in which the magnets 4 are juxtaposed is smaller than the dimension along the same direction of the armature 2 .

In addition, in this embodiment, the linear motor in which the mounting holes 3a are arranged near the magnets 4 along the moving direction of the magnets 4 has been described. However, as shown in FIG. 5 , the number of mounting holes 3a may be reduced.

Embodiment 2

FIG. 6 is a plan view showing the linear motor of this embodiment.

In the linear motor of the present embodiment, the field section 1 has a plurality of magnet groups 7 composed of two magnets 4 arranged in parallel.

When viewed in a direction perpendicular to the facing surface 5 a of the armature core 5 , the magnet group 7 is offset in the direction A relative to the armature core 5 . That is, the magnets 4 of the magnet group 7 are shifted in the same direction, and one end 4 a of each magnet 4 protrudes from the armature core 5 when viewed in a direction perpendicular to the facing surface 5 a of the armature core 5 .

When viewed in a direction perpendicular to the facing surface 5a, adjacent magnet groups 7 are offset from each other by the same amount in the direction A relative to the armature core 5 in opposite directions. In addition, the amount of offset between adjacent magnet groups 7 may be different.

Mounting hole 3a formed on base 3 is formed in a region away from magnet group 7 in a direction opposite to the shifting direction of magnet group 7 when viewed in a direction perpendicular to opposing surface 5a.

Other structures are the same as those in Embodiment 1.

As described above, according to the linear motor of this embodiment, since at least some of the magnets 4 that are shifted in the same direction are adjacent to each other, it is possible to change the pulse frequency of the force acting on the field part 1 and the armature 2 in the A direction. .

As a result, the natural frequency of the mechanical device using the linear motor can be avoided.

In addition, in the present embodiment, the magnet group 7 composed of two magnets 4 arranged in parallel has been described, but the magnet group 7 composed of three or more magnets 4 arranged in parallel may also be used.

Embodiment 3

FIG. 7 is a graph showing the increase rate of the counter electromotive force of the linear motor according to the present embodiment. In addition, in FIG. 7, the case where the dimension L1 of the armature core 5 along the A direction is equal to the dimension L2 of the magnet 4 along the A direction is calculated as 0%. The dotted line shown in FIG. 7 is a reference straight line for comparing the linearity of the graphs representing the counter electromotive force.

In the linear motor of this embodiment, when viewed from a direction perpendicular to the facing surface 5a of the armature core 5, the protrusion length (L2-L1) of the one end portion 4a of the magnet 4 from the armature core 5 is the excitation length (L2-L1). 5 times or less than the gap length gap between part 1 and armature 2.

Other structures are the same as those in Embodiment 1.

In addition, it may be the same as Embodiment 2.

As shown in FIG. 7, when the ratio of the protruding length (L2-L1) of the magnet 4 to the gap length gap is 500% or less, the increase rate of the counter electromotive force generated in the coil 6 is approximately the same as the protruding length of the magnet 4 ( L2-L1) is proportional to the ratio of the gap length gap.

When the ratio of the protrusion length of the magnet 4 to the gap length gap is greater than 500%, even if the protrusion length (L2-L1) is further increased, the back electromotive force hardly increases.

This is because the magnetic flux from the magnet 4 does not interlink with the armature core 5 and leak even if the protruding length ( L2 - L1 ) is increased.

In addition, when viewed from a direction perpendicular to the facing surface 5a of the armature core 5, it is particularly preferable that the length (L2-L1) of the one end portion 4a of the magnet 4 protruding from the armature core 5 be equal to that of the field part 1 and the armature 2. The gap length between gaps is less than 3 times.

As described above, according to the linear motor of the present embodiment, when viewed from the direction perpendicular to the facing surface 5a, since the projecting length (L2-L1) of the one end portion 4a of the magnet 4 protrudes from the armature core 5, the excitation portion 1 and the The gap length gap between the armatures 2 is less than 5 times, so by increasing the protruding length (L2-L1), the counter electromotive force generated in the coil 6 can be effectively increased.

Embodiment 4

FIG. 8 is a plan view showing the linear motor of this embodiment.

In the linear motor of this embodiment, the magnet 4 is inclined at a predetermined angle with respect to the A direction.

Other structures are the same as those in Embodiment 1.

In addition, it may be the same as Embodiment 2 or Embodiment 3.

According to the linear motor of this embodiment, since the magnet 4 is inclined at a predetermined angle with respect to the A direction, the cogging torque can be reduced.

Embodiment 5

FIG. 9 is a perspective view showing a linear motor according to this embodiment, and FIG. 10 is a cross-sectional view taken along line X-X in FIG. 9 .

The linear motor of this embodiment has a pair of field parts 1 facing each other and an armature 2 provided between the field parts 1 .

The armature 2 faces each field section 1 .

Each field part 1 has a flat base 3 and a plurality of magnets 4 arranged on the base 3 as in the first embodiment.

In each excitation part 1, the direction in which the magnets 4 are arranged is mutually the same direction.

As in Embodiment 1, a direction along a straight line perpendicular to the direction in which the magnets 4 are arranged and parallel to the facing surface 5 a of the armature core 5 facing the magnets 4 is defined as the A direction.

The respective magnets 4 of the opposing field parts 1 face each other. In addition, the magnets 4 of the opposing field parts 1 are shifted in opposite directions along the direction A with respect to the armature core 5, and when viewed in a direction perpendicular to the facing surface 5a of the armature core 5, one end of each magnet 4 4a protrudes from the armature core 5 .

Each excitation part 1 is formed with a mounting hole 3a in a region of the base part 3 away from the magnet 4 in a direction opposite to the shifting direction of the magnet 4 when viewed in a direction perpendicular to the facing surface 5a.

Other structures are the same as those in Embodiment 1.

In addition, other structures may be the same as any one of the second to fourth embodiments.

Hereinafter, the force in the direction A acting on the armature core 5 in the linear motor of this embodiment will be described.

On the armature core 5, an attractive force by the magnet 4 acts. When viewed in a direction perpendicular to the opposite surface 5a, the center of the magnet 4 is shifted in the direction A with respect to the center of the armature core 5, so, as shown in FIG. The direction is inclined from the direction perpendicular to the opposite surface 5a to the A direction.

However, since the opposing magnets 4 are shifted in opposite directions along the direction A, the component along the direction A of the attractive force of the magnets 4 attracting the armature core 5 is canceled.

Therefore, the movement in the A direction by which the armature core 5 is attracted by the magnet 4 is suppressed.

On the other hand, as shown in FIG. 11, when the opposite magnets 4 are displaced in the same direction along the direction A, as shown in FIG. The weight of is not offset.

Since the mutually staggered directions of adjacent magnets 4 are opposite directions, so, for example, when there are an even number of magnets 4 facing the armature core 5, each magnet 4 attracts the armature core 5 by the force of attraction force. The components along the A direction are canceled out.

However, when the number of magnets 4 facing the armature core 5 is odd, the component along the A direction of the attraction force of each magnet 4 attracting the armature core 5 is not completely canceled but remains.

As a result, a force in the A direction acts on the armature core 5 .

As described above, according to the linear motor of this embodiment, a pair of field parts 1 are provided facing each other, the armature 2 is provided between the field parts 1, the magnets 4 of the field parts 1 face each other, and the magnets facing each other The shifting directions of 4 are mutually opposite directions, so that the component along the A direction of the attractive force of the armature core 5 attracted by the opposing magnets 4 can be cancelled.

Embodiment 6

FIG. 13 is a plan view showing the field section 1 of the linear motor according to this embodiment.

In the linear motor of this embodiment, the field part 1 further has a cover 8 covering the magnet 4 together with the base part 3 .

Thereby, it is possible to suppress a foreign object from being caught between the field section 1 and the armature 2 . In addition, foreign matter can be prevented from coming into contact with the magnet 4 .

In the cover 8, a through hole 8a communicating with the mounting hole 3a of the base 3 is formed.

Fastening bolts (not shown) are inserted into the through holes 8a and the mounting holes 3a, and the excitation unit 1 is mounted on a supporting member (not shown).

The cover 8 is made of aluminum which is a non-magnetic material. In addition, the cover 8 is not limited to aluminum, and may be made of austenitic stainless steel, plastic, or the like.

Thereby, contact between the magnet 4 and the fastening bolt can be prevented. In addition, it is possible to prevent the fastening bolts and the cover 8 from attracting each other. In addition, the magnetic flux from the magnet 4 can be interlinked with the armature core 5 through the cover 8 .

Furthermore, the cover 8 preferably consists of plastic. Plastic is easier to form the through-hole 8a than iron or the like.

As described above, according to the linear motor of this embodiment, since the cover 8 covering the magnet 4 together with the base 3 is additionally provided, when the excitation part 1 is attached to the support member, the fastening bolt is also attracted by the magnet 4, The fastening bolt is prevented from coming into contact with the magnet 4, and damage to the magnet 4 can be suppressed.

Explanation of reference signs

1 Excitation part, 2 Armature, 3 Base, 3a Mounting hole, 4 Magnet, 4a One end, 4b The other end, 5 Armature core, 5a Opposite surface, 6 Coil, 7 Magnet group, 8 Cover, 8a Pass hole.

Claims (7)

1. A linear motor, characterized in that it has: an excitation part, the excitation part has a base and a plurality of magnets juxtaposed on the base; an armature having an armature core facing the magnet and a coil provided on the armature core, and moving relative to the exciting part in a direction in which the magnets are aligned, When viewed along the direction in which the magnets are aligned, the entire area of the surface of the armature core facing the magnets faces the magnets, When viewed in a direction perpendicular to the opposing surface, some of the plurality of magnets are shifted in one direction relative to the armature core along a straight line intersecting the direction in which the magnets are paralleled, and one end is separated from the armature core. The armature core protrudes, and the remaining magnets are staggered in a direction opposite to the one direction with respect to the armature core and one end protrudes from the armature core, on the base, along the Mounting holes are formed in regions of the magnets that are staggered in opposite directions away from the magnets. 2. The linear motor according to claim 1, wherein the respective shifting directions of the mutually adjacent magnets are opposite to each other. 3. The linear motor according to claim 1, wherein at least some of the magnets shifted in the same direction are adjacent to each other. 4. The linear motor according to any one of claims 1 to 3, wherein when viewed from a direction perpendicular to the opposing surface, the other end of the magnet is aligned with the direction perpendicular to the magnet. The ends of the armature in the direction are on the same straight line along the direction in which the magnets are juxtaposed. 5. The linear motor according to any one of claims 1 to 4, wherein the one end of the magnet protrudes from the armature core when viewed from a direction perpendicular to the facing surface. The protruding length is less than 5 times the length of the gap between the excitation part and the armature. 6. The linear motor according to any one of claims 1 to 5, wherein: A pair of the excitation parts are arranged opposite to each other, the armature is disposed between the excitation parts, The magnets of each of the excitation parts face each other, and the directions of shifting of the magnets facing each other are opposite to each other. 7. The linear motor according to any one of claims 1 to 6, wherein the field part further has a cover covering the magnet together with the base part.

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