Linear motor

Abstract

To achieve improvement of thrust or decrease of heat generation without changing a motor volume or downsize a motor without reducing thrust and without increasing heat generation.SOLUTION: The present invention relates to a linear motor 100 comprising a stator 10 including a plurality of salient poles 12 arrayed at a fixed interval in an extension direction and a slider 20 disposed oppositely to the stator 10 and moving in the extension direction of the stator 10. A U-phase coil core 30 of the slider 20 includes: a yoke 31; a plurality of teeth 32; permanent magnet 34 disposed in each magnet cavity 33 between the teeth; a winding cavity 35 formed outside of a tooth set 32S; and a U-phase coil 36 wound around the winding cavity 35. The plurality of teeth 32 radially protrudes from the yoke 31 to the stator 10, and a width of each of the teeth 32 at the yoke side is narrower than a width at the stator side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the structure of a linear motor in which a permanent magnet is inserted into a slider. [Background technology]

[0002] A linear motor consists of a slider, which is the driving part, and a stator, which is the fixed part, and there are various structures. Among them, the structure of a linear motor with a permanent magnet and windings inside the slider will be explained below.

[0003] FIG. 4 shows an example of the cross-sectional structure of a U-phase winding core 1a of a conventional linear motor 200 with embedded magnets. As will be described later with reference to FIG. 6, the conventional linear motor 200 is composed of a stator 2 and a slider 1. The slider 1 is composed of a U-phase winding core 1a, a W-phase winding core 1b, and a V-phase winding core 1c, which are connected in the X direction. The length of the slider 1 in the X direction is SLLT0, and the height in the Y direction is SLH0. As shown in FIG. 4, the length of the U-phase winding core 1a in the X direction is SLL0. The structures of the W-phase winding core 1b and the V-phase winding core 1c are the same as those of the U-phase winding core 1a, so the structure of the U-phase winding core 1a will be described below. Note that in each figure, the X direction indicates the direction of movement of the slider 1, and the Y direction indicates the direction perpendicular to the X direction.

[0004] As shown in Figure 4, U-phase winding core 1a is positioned opposite stator 2 and moves in the X direction while maintaining a constant distance from stator 2. Both U-phase winding core 1a and stator 2 are constructed with silicon steel plates laminated perpendicular to the plane of the figure. The portions of U-phase winding core 1a that extend toward stator 2 and have a constant width TW0 are called teeth 5. U-phase winding core 1a also has magnet gaps 7 and winding gaps 8. Magnet gap 7 is a slit with a width E, and permanent magnets 3 with rectangular cross sections of width E are placed within it with their magnetic poles facing horizontally in the figure. In this configuration, the magnetic poles of adjacent permanent magnets 3 face each other with the same poles facing each other. For example, if the leftmost permanent magnet has its north pole facing left and its south pole facing right, then the permanent magnet immediately to the right has its south pole facing left and its north pole facing right, resulting in a structure in which the magnetic poles face in opposite directions and face each other with the same poles facing each other. As a result, magnetic flux flows through the teeth 5 as shown by the two-dot chain line in the figure. For example, the magnetic flux coming out of the N pole is divided into magnetic flux heading towards the stator 2 and magnetic flux heading in the opposite direction from the stator 2. Of these, the magnetic flux heading in the opposite direction from the stator 2 goes around the magnet gap 7 and enters the S pole. On the other hand, the magnetic flux heading towards the stator 2 passes through the salient pole 6 of the stator 2 and enters the stator 2. When viewed from the stator 2, at this time, the magnetic poles are lined up in order at the tips of the teeth 5: N pole, S pole, N pole, S pole.

[0005] The teeth 5 of the U-phase winding core 1a are arranged at a constant pitch SLP. This pitch SLP is the sum of the width E of the permanent magnet 3 and the width TWO of the teeth 5. Furthermore, the portion of the stator 2 that faces the U-phase winding core 1a has a salient pole shape. These salient poles 6 are also arranged at a constant pitch STP. Here, the relationship between STP and SLP is as follows: STP=SLP×2...Formula 1 The pitch STP of the salient poles 6 is twice the pitch SLP of the teeth 5. As a result, all of the teeth 5 with the same poles have the same positional relationship as the salient poles 6 of the stator 2.

[0006] Winding gaps 8 are formed outside the multiple teeth 5. The width of the winding gaps 8 in the X direction is width D0. A U-phase winding 4 is placed in the winding gaps 8. The winding 4 is wound between the two winding gaps 8 shown in the figure. When current is passed through the winding 4, magnetic flux is generated parallel to the teeth 5 according to the right-hand rule. This magnetic flux strengthens or weakens the magnetic flux originally generated in the teeth 5 by the permanent magnets 3. For example, as shown in Figure 5, if current is passed from the back to the front of the winding 4 on the left side of the figure and from the front to the back of the winding 4 on the right side, magnetic flux flows from bottom to top within each tooth 5 surrounded by the winding 4. As a result, of the magnetic flux previously generated by the permanent magnets 3, the magnetic flux from bottom to top is strengthened and the magnetic flux from top to bottom is weakened. Because the strength of the magnetic field formed by passing a current through the winding 4 is proportional to the magnitude of the current passing through the winding 4, the weakened magnetic flux may be canceled out and become zero. When the weakened magnetic flux is canceled out and becomes zero, the magnetic flux flows as shown in the diagram. That is, of the magnetic flux coming out of the north pole of the permanent magnet 3, the magnetic flux heading towards the stator 2 is canceled out and becomes zero, and the magnetic flux heading in the opposite direction from the stator 2 is strengthened by the magnetic flux generated by the winding 4. Meanwhile, on the south pole side of the permanent magnet 3, the magnetic flux coming in from the opposite direction to the stator 2 is canceled out and becomes zero, and the magnetic flux coming in from the stator 2 is strengthened. As a result, when viewed from the stator 2, the magnetic pole of the tooth 5 that was previously the north pole disappears, and only south poles are present on every other tooth 5.

[0007] When the teeth 5 and salient poles 6 are directly facing each other, the only force generated between the U-phase winding core 1a and the stator 2 is a magnetic attraction force that pulls them together in the vertical direction in the figure; there is no thrust force that moves the U-phase winding core 1a left or right. However, as the positions of the U-phase winding core 1a and the stator 2 shift left or right from this point, the magnetic attraction force gradually decreases, while the thrust force increases. The magnitude of these forces is proportional not only to their relative positions but also to the strength of the magnetic field at the teeth 5. Therefore, the desired thrust can be obtained by controlling the relative positions of the teeth 5 and the salient poles 6 and the strength of the magnetic field at the teeth 5. The purpose of passing a current through the winding 4 is to control the strength of the magnetic field at the teeth 5 by adjusting the positions of the teeth 5 and the salient poles 6 to obtain the desired thrust.

[0008] As shown in FIG. 6, slider 1 is composed of U-phase winding core 1a, W-phase winding core 1b, and V-phase winding core 1c, which are aligned in the X direction. As explained above, W-phase winding core 1b and V-phase winding core 1c have the same structure as U-phase winding core 1a, with the W-phase winding wound around W-phase winding core 1b and the V-phase winding wound around V-phase winding core 1c. In the figure, the U-phase winding is wound around the portion indicated by U and X, the V-phase winding is wound around the portion indicated by V and Y, and the W-phase winding is wound around the portion indicated by W and Z. As is well known, the currents flowing through the three-phase windings are shifted in phase by 120° electrical angle. Therefore, the positions of teeth 5 must be adjusted accordingly. Here, the electrical angle of 360° is equal to the pitch STP of the salient poles 6, so the spacing SLPW between the teeth sandwiching the portion where the winding 4 is inserted is shifted by 120° or 240° in electrical angle with respect to the salient poles 6, and by STP x 1 / 3 or STP x 2 / 3 in pitch. Expressed as a formula, where n is an integer, SLPW = SLP × n + STP × 1 / 3 Formula 2 SLPW = SLP × n + STP × 2 / 3 Formula 3 By arranging the teeth 5 in the above manner, three-phase AC can be passed through the windings, and thrust can be efficiently generated between the slider 1 and the stator 2.

[0009] In addition, as shown in Figure 5, when current flows through the winding 4, only the same poles are present on every other tooth 5 as viewed from the stator 2. However, if a three-phase winding is wound as shown in Figure 6, with the U-phase winding core 1a, W-phase winding core 1b, and V-phase winding core 1c connected, for example, if the same current as in Figure 5 flows through the U-phase winding, currents out of phase with each other will flow through the V-phase winding and 240 degrees out of phase with each other will flow through the W-phase winding. If a peak current flows through the U-phase, currents that are half the U-phase current but in the opposite direction will flow through the V-phase and W-phase. Therefore, as shown in Figure 6, unlike the U-phase, the V- and W-phases will have a configuration in which stronger N-poles are aligned as viewed from the stator 2. As explained in Figure 5, magnetic flux was generated from the N-pole tooth in the direction opposite to the stator 2. However, because the magnetic flux is canceled out at the adjacent teeth, this magnetic flux cannot enter the S-pole of the permanent magnet 3 and has nowhere to go. However, when three sets of windings are connected as shown in Figure 6, the magnetic flux of the U phase, which has nowhere to go, connects with the magnetic flux generated in the opposite direction in the V and W phases, and can enter the permanent magnet 3. In this case, the part through which the magnetic flux passes is called the yoke. The part of the yoke where the width dimension perpendicular to the direction of the magnetic flux is smallest, that is, the dimension in the Y direction shown as LY0 in Figure 6, is called the yoke height. This yoke height LY0 is set to the minimum value within the range in which the magnetic flux does not saturate when current is applied to the winding 4. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-109639 Summary of the Invention [Problem to be solved by the invention]

[0011] When determining the dimensions of each part in designing the slider 1, the width of the permanent magnet 3 is first determined based on the magnet's demagnetization tolerance. The width of the teeth 5 is then set to the minimum value within the range that will prevent magnetic flux saturation within the teeth 5, even when the magnetic flux from the permanent magnet 3 is intensified by current passing through the windings 4. As mentioned above, the sum of these two widths is the pitch SLP of the teeth 5. Furthermore, the spacing SLPW between the teeth 5, which sandwich the area where the windings 4 are inserted, is determined by either Equation 2 or Equation 3. The height SLH0 of the slider 1 is the sum of the yoke height LY0 and the height SLTH0 of the winding gap 8. The width D0 of the winding gap 8 is determined by the amount of winding wire to be inserted. The amount of winding wire is calculated by multiplying the number of turns (known as the number of turns) by the cross-sectional area of the winding wire per turn. The thrust generated by the motor is proportional to the number of turns and the current passing through it, while the heat generated when current is passed through it is inversely proportional to the cross-sectional area of the winding wire. Therefore, the number of turns is determined from the required thrust and current, and the winding resistance is calculated from the determined number of turns to limit the amount of heat dissipated when current is applied, and the cross-sectional area of the winding is then determined from this. The required amount of winding is determined from the above, and the size of the winding gap 8 can be determined based on this. Once the size of the winding gap 8 is determined, the width D0 is half the length obtained by subtracting the tooth width TWO from the tooth spacing SLPW obtained from Equation 2 or Equation 3, in other words, D0 = (SLPW - TWO) / 2, and from this the height SLTH of the winding gap 8 is determined.

[0012] A typical motor characteristic is required to generate a desired force within a given motor volume while limiting heat generation to a specified value. However, if the desired force cannot be achieved, the number of turns is usually increased due to limitations on the amount of current flowing through the motor. However, increasing the number of turns increases the winding resistance, which proportionally increases heat generation. Therefore, to reduce the winding resistance and heat generation even with an increased number of turns, the cross-sectional area of the winding is increased. One way to increase the cross-sectional area of the winding is to use a thicker-diameter winding, but thicker windings are stiff and difficult to bend, making winding difficult. Therefore, multiple thin wires are typically bundled together to form a single wire. The number of wires bundled together in this case is called the number of parallel windings. Because winding resistance and heat generation are inversely proportional to the number of parallel windings, increasing the number of turns as needed to obtain the desired thrust and increasing the number of parallel windings allows for the design of a motor that generates high force and generates little heat. However, increasing the number of parallel windings increases the amount of winding, which ultimately significantly increases the cross-sectional area of the winding gap 8.

[0013] If the cross-sectional area of the winding gap 8 were to be increased while maintaining the current tooth pitch SLP and the spacing SLPW between the teeth 5 sandwiching the portion where the winding 4 is inserted, the slot height SLTH1 would have to be increased, as in another linear motor 300 shown in Figure 7. Since the yoke height LY0 cannot be changed, the slider 1 height SLH1 would ultimately be larger than before. Then, as in the prior art linear motor 400 shown in Figure 8, even if the tooth spacing is increased to SLPW1 and the width D0 of the winding gap 8 is increased according to Equation 2 or Equation 3, the slider 1 would ultimately have to be longer in the X direction, to a length SLLT9. Thus, attempting to achieve the contradictory goals of increasing thrust and reducing heat generation would result in a larger motor, making it impossible to design within a given volume.

[0014] Therefore, an object of the present invention is to increase the thrust and reduce heat generation without increasing the motor volume. [Means for solving the problem]

[0015] The linear motor of the present invention is a linear motor having a stator having a plurality of salient poles arranged at regular intervals in an extension direction, and a slider disposed opposite the stator and moving along the extension direction of the stator, wherein the slider comprises a yoke, a plurality of teeth protruding from the yoke towards the stator and arranged side by side in the movement direction, permanent magnets respectively arranged in magnet gaps between the teeth, winding gaps formed outside tooth sets consisting of the plurality of teeth, and a winding wound around the winding gaps, and the plurality of teeth are all The teeth protrude radially from the yoke toward the stator, and the width of each of the teeth on the yoke side is narrower than the width of each tooth on the stator side. the width is a length in a direction perpendicular to the protruding direction of each of the teeth; It is characterized by:

[0016] In this way, multiple teeth project radially from the yoke toward the stator, and the width of each tooth on the yoke side is narrower than its width on the stator side. This reduces the width of the tooth group in the direction of movement on the yoke side, and widens the width of the winding gap formed outside the tooth group on the yoke side. Furthermore, narrowing the width of the teeth on the yoke side reduces the magnetic flux passing through the yoke, allowing the yoke height to be lowered and the height of the winding gap to be increased. This allows the cross-sectional area of the winding gap to be increased and the amount of winding to be increased without increasing the motor volume, thereby increasing thrust and reducing heat generation.

[0017] In the linear motor of the present invention, The angles between the protruding direction of one of the teeth and the protruding direction of the other adjacent teeth are all equal, The widths of the teeth at the yoke side ends may all be equal.

[0018] This allows the magnetic flux flowing through each tooth to flow smoothly, thereby reducing heat generation.

[0019] In the linear motor of the present invention, the tip of each tooth on the front side of the tooth set is inclined forward with respect to an opposing direction perpendicular to the movement direction, and the tip of each tooth on the rear side of the tooth set is inclined backward with respect to the opposing direction, and the space forward of the front-end tooth at the front end of the tooth set in the movement direction and the space rearward of the rear-end tooth at the rear end of the tooth set in the movement direction may each form the winding gap portion.

[0020] This allows the width of the winding gap in the direction of movement on the yoke side to be Wide It is possible to increase the cross-sectional area of the winding gap and reduce heat generation without increasing the motor volume. [Effects of the Invention]

[0021] By using the present invention, it is possible to realize a linear motor that can reduce heat generation and increase thrust without increasing the motor volume. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a linear motor according to an embodiment. [Figure 2] 3 is a cross-sectional view showing a U-phase winding core of the linear motor according to the embodiment. FIG. [Figure 3] 3 is an explanatory diagram showing the flow of magnetic flux when a current flows through a U-phase winding of a U-phase winding core of the linear motor in the embodiment. FIG. [Figure 4] FIG. 1 is a cross-sectional view of a U-phase winding core of a linear motor according to the prior art. [Figure 5] 10 is an explanatory diagram showing the flow of magnetic flux when a current flows through a U-phase winding of a U-phase winding core of a linear motor in the prior art. FIG. [Figure 6] FIG. 1 is a diagram showing an example of a cross-sectional structure of a linear motor according to a conventional technique. [Figure 7] FIG. 10 is a diagram showing an example of a cross-sectional structure of another linear motor according to the prior art. [Figure 8]FIG. 10 is a diagram showing an example of a cross-sectional structure of another linear motor according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0023] A linear motor 100 according to an embodiment will be described below with reference to the drawings. As shown in FIG. 1, the linear motor 100 is composed of a stator 10 and a slider 20. In each drawing, the X direction indicates the extension direction of the stator 10 or the movement direction of the slider 20. The Y direction indicates the opposing direction perpendicular to the X direction, which is the movement direction. In the following description, the negative side of the X direction will be the front of the slider 20, and the positive side of the X direction will be the rear of the slider 20.

[0024] The stator 10 is formed by laminating silicon steel plates, for example. The stator 10 is composed of a long stator yoke 11 extending in the X direction and a plurality of salient poles 12 protruding from the Y-direction end face of the stator yoke 11 toward the positive side of the Y direction. The plurality of salient poles 12 are arranged in the X direction at a fixed pitch STP.

[0025] The slider 20 is formed, for example, by laminating silicon steel plates and faces the stator 10 in the Y direction. The slider 20 is composed of a U-phase winding core 30, a W-phase winding core 40, and a V-phase winding core 50, which are connected in the X direction. The length of the slider 20 in the X direction is SLLT1 and the height in the Y direction is SLH. The lengths of the U-phase winding core 30, W-phase winding core 40, and V-phase winding core 50 in the X direction are all SLL1.

[0026] The U-phase winding core 30 includes a yoke 31 with a height LY in the Y direction and multiple teeth 32a-32f that protrude from the yoke 31 toward the stator 10 on the negative side of the Y direction and are aligned in the X direction. Permanent magnets 34a-34e are attached to magnet gaps 33 between the teeth 32a-32f. The multiple teeth 32a-32f form a teeth set 32S, and a winding gap 35 is formed outside the teeth set 32S. The length of the yoke side of the teeth set 32S in the X direction is TWA, and the width of the winding gap 35 in the X direction on the yoke side is D, and the height in the Y direction is SLTH. A U-phase winding 36 is wound around the portion of the winding gap 35 indicated by U and X. When the teeth 32a-32f and the permanent magnets 34a-34e are not distinguished from one another, they are referred to as teeth 32 and permanent magnets 34, respectively.

[0027] The W-phase winding core 40 and the V-phase winding core 50 have the same structure as the U-phase winding core 30, and each include a yoke 41, 51 and a plurality of teeth 42, 52, with permanent magnets 44, 54 attached to magnet gaps 43, 53 between each tooth 42, 52. A W-phase winding 46 and a V-phase winding 56 are wound around winding gaps 45, 55 on the outside of each pair of teeth 42, 52. The W-phase winding 46 is wound around the portions indicated by W and Z in FIG. 1, and the V-phase winding 56 is wound around the portions indicated by V and Y in FIG. 1.

[0028] Each tooth 32 of U-phase winding core 30, each tooth 42 of W-phase winding core 40, and each tooth 52 of V-phase winding core 50 are arranged at a pitch STP / 3, which corresponds to an electrical angle of 120 degrees, in the X direction relative to salient poles 12 of stator 10. The spacing between teeth 32, 42 across winding gaps 35, 45, and the spacing between teeth 42 and 52 across winding gaps 45, 55 are each SLPW, the same as in the prior art shown in FIG. 6, and are defined by Equation 2.

[0029] Next, with reference to Figure 2, the detailed structure of the U-phase winding core 30 will be described. As shown in Figure 2, each of the teeth 32a-32f protrudes from the stator 10 so as to be inclined relative to the Y direction. As shown in Figure 2, if the axis extending toward the negative Y direction at the center of the U-phase winding core 30 in the X direction is defined as the Y1 axis, the two central teeth 32c and 32d of the U-phase winding core 30 are inclined forward and backward by an angle θ1 relative to the Y1 axis. Furthermore, the two outer teeth 32b and 32e are inclined forward and backward by an angle 2θ1 relative to the central teeth 32c and 32d. The outermost front end tooth 32a and rear end tooth 32f are inclined forward and backward by an angle 2θ1 relative to the teeth 32b and 32e. In this way, the tips of the front teeth 32a to 32c of the teeth set 32S are inclined forward with respect to the Y1 axis, and the tips of the rear teeth 32d to 32f are inclined backward with respect to the Y1 axis.

[0030] Here, the angle between the two central teeth 32c, 32d is 2θ1, and therefore each of the teeth 32a to 32f is disposed at an angle 2θ1 relative to the adjacent teeth, and each of the teeth 32a to 32f protrudes radially from the yoke 31 toward the stator 10 at an equal angle of 2θ1. The space in front of the tooth 32a at the front end of the tooth set 32S in the X direction and the space behind the tooth 32f at the rear end of the tooth set 32S in the X direction each form a winding gap 35.

[0031] A magnet gap 33 is provided in the center between each of the teeth 32a to 32f. As shown in FIG. 2, the magnet gap 33 is a slit with a constant width E into which a permanent magnet 34 with a rectangular cross section is attached. Each of the teeth 32a to 32f is disposed at an angle 2θ1 with respect to the adjacent teeth, but the two opposing faces of the magnet gap 33 with a rectangular cross section are parallel. Therefore, the front and rear faces of each of the teeth 32a to 32f are not parallel, and the width narrows from the stator 10 toward the yoke 31. As shown in FIG. 2, the width TW1 of each of the teeth 32a to 32f on the yoke side is narrower than the width TW2 on the stator side.

[0032] If the midpoint of the edge of each of the teeth 32a to 32f is called the center of the tooth 32a to 32f, the pitch SLP in the X direction between the centers of the teeth 32a to 32f satisfies Equation 1 with respect to the pitch STP of the salient poles 12 of the stator 10, as in the prior art, and all have the same dimension. Also, the width of the salient poles 12 of the stator 10 is the same as in the prior art.

[0033] Each magnet gap 33 is located in the center between each tooth 32a to 32f, and therefore, like each tooth 32a to 32f, each magnet gap 33 is arranged at an angle 2θ1 to the adjacent magnet gap 33, and each magnet gap 33 extends radially from the yoke 31 toward the stator 10 at an equal angle of 2θ1.

[0034] A permanent magnet 34a to 34e is attached to each magnet gap 33. The permanent magnets 34a to 34e have a rectangular cross section with a width E. As in the prior art, the magnetic poles of the permanent magnets 34a to 34e are oriented perpendicular to the long sides of the permanent magnets 34a to 34e, and the permanent magnets 34a to 34e are attached so that the same poles face each other across the teeth 32a to 32e.

[0035] Since each permanent magnet 34a to 34e is attached to each magnet gap portion 33, it is arranged at an angle 2θ1 to the adjacent permanent magnet, and each permanent magnet 34a to 34e is arranged so that the long sides extend radially from the yoke 31 toward the stator 10 at an equal angle of 2θ1.

[0036] With the above configuration, the length TWB of the teeth set 32S on the stator side in the X direction is TWB≒TW2×6+5×E Equation 4 Here, the stator-side width TW2 of the teeth 32a and 32f is approximately equal to the width TW0 of the teeth 5 of the prior art shown in FIG. 4, and the width E of each permanent magnet is also approximately equal to the width E of the permanent magnet 3 of the prior art. Therefore, TWB becomes approximately equal to the X-direction length TWA0 of the tooth set according to the prior art. In Equation 4, the influence of the inclination angles of the teeth 32a to 32f and the permanent magnets 34a to 34e is small and thus ignored.

[0037] On the other hand, the X-direction length TWA of the yoke side of the tooth set 32S is TWA ≒ TW1 × 6 + E × 5 ··· Equation 5 This is the case. Similar to Equation 4, Equation 5 also ignores the influence of the inclination angles of the teeth 32a to 32f and the permanent magnets 34a to 34e. As described above, since TW1 < TW2, TWA < TWB ≒ the X-direction length TWA0 of the tooth set according to the prior art ·· Equation 6 This is the result.

[0038] Therefore, in the U-phase winding core 30 of the linear motor 100 of the embodiment, the X-direction length TWA of the yoke side of the tooth set 32S becomes shorter than the X-direction length TWA0 of the tooth set according to the prior art shown in FIG. 4. Therefore, when the X-direction length SLL1 of the U-phase winding core 30 is made the same as the X-direction length SLL0 of the U-phase winding core 1a of the prior art, the X-direction width D of the yoke side of the winding gap portion 35 formed outside the tooth set 32S can be made wider than the width D0 of the winding gap portion 8 of the prior art.

[0039] Still, as described with reference to FIG. 1, the interval between the teeth 32 and 42 sandwiching the winding gap portions 35 and 45 is the same SLPW as that of the prior art shown in FIG. 6, and the width TW2 of the tip of the tooth 32 is approximately equal to the width TW0 of the tooth 5 of the prior art shown in FIG. 4. Therefore, the stator-side width Ds of the winding gap portion 35 is Ds = (SLPW - TW2) / 2 ≒ (SLPW - TW0) / 2 = D0 ·· Equation 7 This results in being approximately the same width as the width D0 of the winding gap portion 8 of the U-phase winding core 1a of the prior art shown in FIG. 4.

[0040] Next, referring to FIG. 3, we will explain the flow of magnetic flux generated in the teeth 32a-32f when current flows through the winding 36. When current flows through the winding 36, the generated magnetic flux strengthens or weakens the magnetic flux in the teeth 32a-32f according to the right-hand screw rule, as in the prior art. As shown in FIG. 3, the leftmost permanent magnet 34a has a north pole on the left side and a south pole on the right side, and the permanent magnets 34b-34e are arranged in order from there so that their like poles face each other. In this case, if current is passed through the left winding 36 from the back to the front and through the right winding 36 from the front to the back, magnetic flux is generated between the windings 36 toward the positive side in the Y direction according to the right-hand screw rule. Therefore, the magnetic flux generated from the north poles of the permanent magnets 34a-34e and flowing toward the stator 10 in the negative Y direction is weakened, and the magnetic flux flowing toward the positive Y direction, opposite the stator 10, is strengthened. In addition, the magnetic flux that enters the south pole of the permanent magnets 34a to 34e and moves from the stator 10 toward the permanent magnets 34a to 34e in the positive Y direction is strengthened, and the magnetic flux that enters the permanent magnets 34a to 34e from the yoke 31 in the negative Y direction is weakened.

[0041] In the linear motor 100 of this embodiment, the width TW1 of each tooth 32a-32f on the yoke side in the X direction is narrower than the width TW2 of each tooth 32a-32f on the stator side in the X direction, so compared to the conventional structure, the magnetic resistance at the yoke side end of each tooth 32a-32f is greater, making it relatively more difficult for magnetic flux to pass through. The width TW1 of each tooth 32a-32f on the yoke side is narrower than the width TW0 of the tooth 5 in the conventional technology, and the magnetic resistance is (TW0 / TW1) times, making it more difficult for magnetic flux to pass through.

[0042] Generally, magnetic flux flows more easily in the direction of least magnetic resistance, and as magnetic resistance increases, the magnetic flux passing through that portion decreases. Therefore, as the magnetic resistance of each tooth 32a-32f increases on the yoke side, the magnetic flux from each tooth 32a-32f toward the yoke 31 in the direction opposite to the stator 10 decreases, and the magnetic flux passing through the yoke 31 to connect adjacent phases also decreases. This makes it less likely for magnetic flux to saturate in the yoke 31 than in the slider 1 of the prior art, and the Y-direction height LY of the yoke 31 can be made smaller than the Y-direction height LY0 of the prior art shown in FIG. 4. For a given height SLH of the slider 20, reducing the Y-direction height LY of the yoke 31 allows the Y-direction height SLTH of the winding gap 35 to be increased by that amount compared to the Y-direction height SLTH0 of the winding gap 8 of the prior art.

[0043] As described above, in the U-phase winding core 30 of the linear motor 100 of this embodiment, multiple teeth 32a-32f project radially from the yoke 31 toward the stator 10, and the width TW1 on the yoke side of each of the teeth 32a-32f is narrower than the width TW2 on the stator side. As a result, when the length SLL1 in the X direction and the height SLH of the U-phase winding core 30 are the same as the length SLL0 and height SLH0 of the U-phase winding core 1a of the prior art shown in FIG. 4, the width D in the X direction and the height SLTH in the Y direction on the yoke side of the winding gap 35 can be made larger than the width D0 in the X direction and the height SLTH0 in the Y direction of the winding gap 8 of the prior art, respectively. This makes it possible to make the cross-sectional area of the winding gap 35 larger than the cross-sectional area of the winding gap 8 of the prior art. This allows the amount of winding 36 to be increased compared to the amount of winding 4 of the U-phase winding core 1a of the prior art without increasing the volume of the U-phase winding core 30, thereby increasing the thrust of the U-phase winding core 30 and reducing heat generation.

[0044] The above has described the details of the structure of the U-phase winding core 30. However, the W-phase winding core 40 and the V-phase winding core 50 have the same structure as the U-phase winding core 30. If the length SLL1 in the X direction and the height SLH of the W-phase winding core 40 and the V-phase winding core 50 are the same as the length SLL0 and height SLH0 of the prior art W-phase winding core 1b and V-phase winding core 1c shown in FIG. 4, then the yoke-side width D in the X direction and height SLTH in the Y direction of the winding gaps 45, 55 can be made larger than the width D0 in the X direction and height SLTH0 in the Y direction of the winding gap 8 in the prior art, respectively. This allows the cross-sectional area of the winding gaps 45, 55 to be made larger than the cross-sectional area of the winding gap 8 in the prior art.

[0045] Therefore, in the slider 20 formed by connecting the U-phase winding core 30, the W-phase winding core 40, and the V-phase winding core 50 in the X direction, when the length SLLT1 in the X direction and the height SLH in the Y direction of the slider 20 are the same as the length SLLT0 in the X direction and the height SLH0 in the Y direction of the slider 1 of the prior art shown in Figure 6, the width D in the X direction and the height SLTH in the Y direction of the winding gaps 35, 45, 55 on the yoke side can be made larger than the width D0 in the X direction and the height SLTH0 in the Y direction of the winding gap 8 of the prior art, respectively, and the cross-sectional areas of the winding gaps 35, 45, 55 can be made larger than the cross-sectional areas of the winding gaps 8 of the prior art. Therefore, in the linear motor 100 of the embodiment, the amount of winding 36 for each phase can be increased compared to the amount of winding 4 for each phase of the prior art without increasing the motor volume, thereby increasing the thrust of the slider 20 and reducing heat generation.

[0046] If there is no particular need to improve the characteristics, the motor volume may be reduced to achieve miniaturization. Specifically, the height LY of the yoke 31 and the height SLTH of the winding gap may be reduced to reduce the height SLH of the slider 20, or the width E of the permanent magnets 34a-34e may be reduced to shorten the overall length of the slider 20, since the current required to generate the same thrust can be reduced, thereby reducing the risk of demagnetization of the permanent magnets 34a-34e.

[0047] In the above description, the teeth 32a-32f, magnet gaps 33, and permanent magnets 34a-34e of the U-phase winding core 30 are inclined at an angle of 2θ1 relative to one another, but this is not limiting and the inclination angles may be different. Furthermore, the teeth 32a-32f, magnet gaps 33, and permanent magnets 34a-34e do not all have to protrude radially. For example, the teeth 32c-32d, magnet gap 33, and permanent magnet 34c in the center of tooth set 32S may extend toward stator 10 in the Y direction without being inclined, the tips of teeth 32a-32b, magnet gap 33, and permanent magnets 34a-34b on the front side of tooth set 32S may be inclined forward in the Y direction, and the tips of teeth 32e-32f, magnet gap 33, and permanent magnets 34d-34e on the rear side of tooth set 32S may be inclined backward in the Y direction. The same applies to W-phase winding core 40 and V-phase winding core 50.

[0048] Furthermore, although the pitch STP of the salient poles 12 of the stator 10 has been described as being twice the pitch SLP of the teeth 32, it does not have to be twice as large and may be changed arbitrarily depending on the control method of the linear motor 100 and the number of teeth 32. [Explanation of symbols]

[0049] 1, 20 slider, 1a, 30 U-phase winding core, 1b, 40 W-phase winding core, 1c, 50 V-phase winding core, 2, 10 stator, 3, 34, 44, 54 permanent magnet, 4 winding, 5, 32, 32a to 32f, 42, 52 teeth, 6, 12 salient pole, 7, 33, 43, 53 magnet gap, 8, 35, 45, 55 winding gap, 11 stator yoke, 31, 41, 51 yoke, 32S teeth set, 36 U-phase winding, 46 W-phase winding, 56 V-phase winding, 100, 200, 300, 400 linear motor.

Claims

1. a stator having a plurality of salient poles arranged at regular intervals in an extension direction; a slider disposed opposite the stator and moving along the extension direction of the stator, The slider includes: York and a plurality of teeth protruding from the yoke toward the stator and arranged side by side in a moving direction; a permanent magnet disposed in each magnet gap between the teeth; a winding gap formed outside a teeth set composed of a plurality of the teeth; a winding wound around the winding gap, All of the plurality of teeth protrude radially from the yoke toward the stator, The width of each tooth on the yoke side is narrower than the width on the stator side, the width is a length in a direction perpendicular to the protruding direction of each of the teeth; A linear motor characterized by:

2. 2. The linear motor according to claim 1, the angles between the protruding direction of one of the teeth and the protruding direction of the other adjacent teeth are all equal, and the widths of the yoke side ends of each of the teeth are all equal; A linear motor characterized by:

3. 3. The linear motor according to claim 1 or 2, a tip of each of the teeth on the front side of the teeth set is inclined forward with respect to an opposing direction perpendicular to the moving direction, Each of the teeth on the rear side of the teeth set has a tip that is inclined rearward with respect to the opposing direction, a space in front of a front-end tooth at a front end of the teeth set in the movement direction and a space in rear of a rear-end tooth at a rear end of the teeth set in the movement direction each constitute the winding gap; A linear motor characterized by:

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