Coreless motor

Abstract

In order to change properties of a motor without reducing the degree of freedom of design of the motor, a coreless motor (100) comprises a rotational shaft (20), a coil (60) which is formed in a cylinder shape by winding a conducting wire (61) and which rotates integrally with the rotational shaft (20), and a cylindrical magnet (30) which is disposed inside or outside the cylinder shape of the coil (60), wherein the angle interval (β) about the axis (about the center C) of the rotational shaft (20) between conducting wires 61 (as one example, between two parallel parts (62), (62)) in one winding of the coil (60) is set to be different from the angle interval (α) about the axis (about the center C) of the rotational shaft (20) between poles (30N, 30S) of the magnet (30).

Description

Coreless motor

[0001] The present invention relates to a coreless motor.

[0002] Coreless motors do not have an iron core where the coil serves as the core, and the rotor is formed only by windings. One way to wind the conductor to form the coil is to form it in a hexagonal (tortoiseshell) shape. In this tortoiseshell winding method, for example, the conductor is wound circumferentially around the outer surface of a hexagonal prism while being shifted slightly in the axial direction of the hexagonal prism to form a hexagonal spiral coil element, and the hexagonal prism is then pulled out axially from the coil element to obtain a coil element formed in the spiral shape of a hexagonal prism using only the conductor.

[0003] Then, the sides corresponding to the opposing faces of the hexagonal prism are flattened by moving them in opposite directions along the axial direction of the hexagonal prism, and the resulting planar coil elements are strung together and connected at their axial ends to form a cylindrical coil.

[0004] The coil formed in a cylindrical shape is formed by a portion located on the outer surface side of the cylinder and a portion located on the inner surface side, and both the outer surface side and the inner surface side have a parallel portion parallel to the axis of the cylinder and two hypotenuse portions adjacent to the parallel portion and inclined with respect to the axis.

[0005] Here, the angular interval around the motor's axis between the two parallel parts of one turn of the hexagonal coil is generally formed to match the angular interval around the axis of the motor's magnet. Specifically, for example, if the angular interval around the axis between the north and south poles of the motor's magnet (hereinafter referred to as the magnetic pole pitch) is 180 degrees, the angular interval around the axis between the two parallel parts of the coil (hereinafter referred to as the coil pitch) is also set to 180 degrees.

[0006] In addition, some coreless motors are configured such that the angular spacing between coil elements does not match the magnetic pole pitch, due to the cost and workability considerations in the manufacturing process (see, for example, Patent Document 1).

[0007] Japanese Unexamined Patent Publication No. 1-186143

[0008] When changing various motor characteristics, it is common to change the dimensions of the parallel portion of the coil or the number of turns of the coil. For example, to increase the output torque, which is one of the motor characteristics, this is done by lengthening the dimensions of the parallel portion of the coil, and to increase the rotational speed, which is also one of the motor characteristics, this is done by reducing the number of turns of the coil.

[0009] However, if the overall length of the coil is increased to increase the dimension of the parallel portion of the coil, the overall length of the motor will also increase, and if the overall length of the coil is not changed, changing the inclination angle of the hypotenuse of the coil will increase the radial thickness of the hypotenuse, resulting in a larger diameter of the motor. Also, if the number of turns of the coil is reduced to increase the rotation speed of the motor, there is a risk that the rigidity of the coil will decrease.

[0010] That is, changing the characteristics of the motor reduces the degree of freedom in motor design.

[0011] The present invention has been made in view of the above circumstances, and has as its object to provide a coreless motor whose motor characteristics can be changed without reducing the degree of freedom in motor design.

[0012] The present invention is a coreless motor comprising a rotating shaft, a coil formed into a cylindrical shape by winding a conducting wire and rotating integrally with the rotating shaft, and a cylindrical magnet arranged inside or outside the cylindrical shape of the coil, wherein the angular interval β between the conducting wire in one turn of the coil around the axis of the rotating shaft is set to be different from the angular interval α between the magnetic poles of the magnet around the axis of the rotating shaft.

[0013] According to the coreless motor of the present invention, the characteristics of the motor can be changed without reducing the degree of freedom in motor design.

[0014] FIG. 1 is a cross-sectional view showing a longitudinal section including the center C of the rotating shaft of the coreless motor of embodiment 1. FIG. 2 is a perspective view showing the coil of the coreless motor shown in FIG. 1. FIG. 3 is a schematic view showing step 1 of manufacturing the coil shown in FIG. 2. FIG. 4 is a schematic view showing step 2 of manufacturing the coil shown in FIG. 2. FIG. 5 is a diagram showing a schematic representation of the positional relationship between a magnet and a hexagonal shape for one turn of the coil. FIG. 6 is a schematic view showing the total length along the axial direction of the center C of the coil and the length of the parallel part. FIG. 7 is a schematic view showing the magnitude relationship between the magnetic pole pitch and the coil pitch in a coreless motor. 10 shows a graph illustrating the maximum torque output by one turn of the conductor wire of the coil when the ratio of the coil pitch to the magnetic pole pitch is 0.95, 1.00, 1.05, 1.10, 1.25 (95, 100, 105, 110, 125[%]) for each coil in which the ratio of the length of the parallel portion to the total length of the coil is set to 0.25, 0.30, 0.35, 0.40, 0.45 (25, 30, 35, 40, 45[%]). This is a schematic diagram equivalent to FIG. 6, showing a modified example in which the coil pitch is formed with a short pitch smaller than the magnetic pole pitch.

[0015] An embodiment of a coreless motor according to the present invention will be described below with reference to the drawings.

[0016] <Embodiment 1> Fig. 1 is a cross-sectional view showing a longitudinal section of coreless motor 100 including center C of rotating shaft 20, Fig. 2 is a perspective view showing coil 60 of coreless motor 100 shown in Fig. 1, and Figs. 3A and 3B are schematic diagrams showing the process of manufacturing coil 60. Coreless motor 100 is one embodiment (Embodiment 1) of a coreless motor according to the present invention.

[0017] As shown in FIG. 1 , the coreless motor 100 includes a rotating shaft 20 , a coil 60 , a commutator 50 , a magnet 30 , brushes 40 , and a housing 10 .

[0018] The housing 10 is formed in a hollow cylindrical shape with both ends closed. The housing 10 accommodates a rotating shaft 20, a coil 60, a commutator 50, a magnet 30, and brushes 40 inside the hollow interior, with both ends of the rotating shaft 20 protruding outside the housing 10. The housing 10 includes a case 11 and a brush base 12.

[0019] The case 11 is formed in a cylindrical shape with one end closed. The case 11 is formed, for example, from a soft magnetic material. The brush base 12 is formed in a generally circular plate shape so as to close the open end of the case 11. The brush base 12 is formed, for example, from a resin. The brush base 12 is provided with a conductor connecting member (not shown) that is connected to an external power source, and brushes 40 that are electrically connected to this connecting member.

[0020] A rotating shaft 20 is disposed at the center C, which is the axis of the cylinder of the housing 10, and passes through the housing 10 so as to be rotatable about the center C. A commutator 50 is fixed to the rotating shaft 20. A coil 60 is fixed to the commutator 50. In other words, the rotating shaft 20, the coil 60, and the commutator 50 constitute a rotor.

[0021] As shown in Fig. 2, the coil 60 is formed into a cylindrical shape by winding a conductor 61 (see Figs. 3A and 3B). The coil 60 rotates integrally with the rotating shaft 20, with the center C of the rotating shaft 20 as its axis. The coil 60 is formed by assembling a plurality of coil elements, each of which is wound with a conductor 61 (e.g., copper wire). The coil 60 is formed so that the outer peripheral surface 60A of the cylinder does not come into contact with the inner peripheral surface 11B of the case 11. Details of the coil 60 will be described later.

[0022] The commutator 50 is formed in the shape of a disk having a boss at the center through which the rotary shaft 20 passes. The outer periphery of the disk of the commutator 50 is bonded with an adhesive to the inner periphery of one end of the cylindrical coil 60, which is closer to the brush base 12, thereby being integrated with the coil 60. The commutator 50 is integrally connected to the rotary shaft 20 which passes through the boss, and as a result, the commutator 50 rotates around the center C together with the rotary shaft 20.

[0023] The commutator 50 has a conductive member electrically connected to the terminals 61a, 61b (see Figures 2, 3A, and 3B) of each of the conductors 61 of the multiple coil elements that make up the coil 60, and this conductive member extends to the outer surface of the boss and contacts the brush 40 provided on the brush base 12.

[0024] Magnet 30 is disposed inside the cylinder of coil 60 so as not to come into contact with inner peripheral surface 60B of coil 60. Magnet 30 is formed in a cylindrical shape with its axis at center C. Magnet 30 is formed so that outer peripheral surface 30A does not come into contact with inner peripheral surface 60B of coil 60. Magnet 30 has inner peripheral surface 30B fixed to the outer peripheral surface of cylindrical support member 28 fixed to case 11.

[0025] As a result, the magnet 30 is indirectly fixed to the case 11 and does not displace relative to the case 11. Inside the support member 28, bearings 25 are arranged at both ends in the longitudinal direction of the support member 28, and the rotating shaft 20 is rotatably supported by these two bearings 25.

[0026] Next, the details of the coil 60 will be described as follows. The coil 60 is basically made up of conductors 61 joined together with an adhesive, and does not have a core such as an iron core. Therefore, the coil 60 is lighter than a coil with a core.

[0027] As shown in FIG. 3A , the coil 60 is formed by winding a conducting wire 61 around the outer circumferential surface of a winding jig 500 having a hexagonal cross section, for example, a hexagonal prism shape. At this time, the position at which the conducting wire 61 is wound is shifted slightly in the axial direction of the hexagonal prism for each turn of the winding (each turn around the outer circumferential surface of the hexagonal prism), thereby forming a spiral coil 60 in which each turn has a hexagonal (tortoiseshell) shape.

[0028] In Figures 3A and 3B, the hexagons formed by the conductor 61 are depicted as if they were separate and independent, but this is for the convenience of simplifying the depiction in the figures. In reality, the conductor 61 depicted as multiple hexagons has both ends of one turn of the conductor 61 in each hexagonal shape connected to the ends of one turn of another hexagonal shape to form a single spiral, and this single spiral conductor 61 has both ends 61a and 61b.

[0029] By pulling out the winding jig 500 in the axial direction from the hexagonal spiral coil 60 thus formed, a hexagonal spiral coil 60 is obtained using only the conductor wire 61. Then, the sides of the coil 60 corresponding to the opposing faces of the hexagonal prism of the winding jig 500 are moved in opposite directions along the axial direction of the hexagonal prism (indicated by "→" in FIG. 3A), thereby forming the flattened coil 60 shown in FIG. 3B.

[0030] The coil 60 shown in Fig. 3B is used as one coil element, and a plurality of such coil elements are strung together in the axial direction of the above-mentioned hexagonal prism, and the ends in the axial direction are connected around the center C shown in Fig. 3B so that one surface 60A of the planar coil element faces outward (outer circumferential surface) and the other surface 60B faces inward (inner circumferential surface), thereby forming the cylindrical coil 60 shown in Fig. 2. Note that the method of forming the coil 60 is not limited to the method described above.

[0031] The coil 60 thus formed is a tortoiseshell-shaped (hexagonal) coil 60, and as shown in Fig. 2, on both the outer peripheral surface 60A and the inner peripheral surface 60B of this coil 60, the conductor 61 has a parallel portion 62 extending parallel to the axial direction (center C) of the rotating shaft 20, and two oblique portions 63, 64 connected to both ends of the parallel portion 62. The conductor 61 of the oblique portions 63, 64 extends in a direction inclined by a predetermined angle θ with respect to a plane (shown by a dot-dash line in Fig. 3B) perpendicular to the direction of the center C. As shown in Fig. 3B, the inclination angle θ of the oblique portion 63 and the inclination angle θ of the oblique portion 64 are in different directions but have the same absolute value.

[0032] 3B , when it is necessary to distinguish between the parallel portion 62 on the outer peripheral surface 60A of the coil 60 and the parallel portion 62 on the inner peripheral surface 60B, the parallel portion 62 on the outer peripheral surface 60A is referred to as the parallel portion 62a, and the parallel portion 62 on the inner peripheral surface 60B is referred to as the parallel portion 62b. Similarly, when it is necessary to distinguish between the oblique side portions 63, 64 on the outer peripheral surface 60A of the coil 60 and the oblique side portions 63, 64 on the inner peripheral surface 60B, the oblique side portions 63, 64 on the outer peripheral surface 60A are referred to as the oblique side portions 63a, 64a, and the oblique side portions 63, 64 on the inner peripheral surface 60B are referred to as the oblique side portions 63b, 64b.

[0033] FIG. 4 is a diagram schematically illustrating the positional relationship between the magnet 30 and the hexagonal shape of one turn of the coil 60. The magnet 30 in the coreless motor 100 of this embodiment is, for example, as shown in FIG. 4 , formed with one north pole 30N and one south pole 30S on either side of the axis of the center C. That is, the magnet 30 is formed with the north pole 30N and the south pole 30S arranged at an angular interval (angular pitch) α of 180 degrees around the axis of the center C of the magnet 30. The center of the north pole 30N (north pole center) and the center of the south pole 30S (south pole center), indicated by the dashed dotted lines in FIG. 4 , are angular positions at which the absolute value of the magnetic force distribution of the magnet 30 is maximized. In the following description, the angular pitch α between the center of the north pole 30N and the center of the south pole 30S is referred to as the magnetic pole pitch α.

[0034] Although the two-dot chain line in FIG. 4 indicates the boundary between the north pole 30N and the south pole 30S, the magnet 30 is not structurally separated at this boundary.

[0035] 4, the coil 60 in the coreless motor 100 of this embodiment is formed such that two parallel portions 62, 62 in one hexagonal turn are spaced apart at an angular interval (angular pitch) β around the axis of the center C of the magnet 30. The two parallel portions 62, 62 are the portions in one turn of the coil 60 where the angular interval around the axis of the center C is maximum. In the following description, the angular pitch β will be referred to as the coil pitch β.

[0036] Fig. 5 is a schematic diagram showing the overall length L0 of the coil 60 along the axial direction of the center C and the length L1 of the parallel portion 62. Fig. 6 is a schematic diagram showing the relationship between the magnetic pole pitch α and the coil pitch β in the coreless motor 100, and also shows the magnetic force distribution expressed by a trigonometric function, where the magnetic force of the magnet 30 is greatest at the center of the north pole 30N and the center of the south pole 30S.

[0037] As shown in FIG. 5, the coreless motor 100 has a coil 60 in which the ratio (length ratio) L1 / L0 of the length L1 of the parallel portion 62 to the total length L0 along the axial direction of the center C is set to be 0.25 (25% or more) and 0.45 (45% or less).

[0038] 6, the coreless motor 100 is formed with an over-pitch, where the coil pitch β is greater than the magnetic pole pitch α (α<β). In other words, the coreless motor 100 is set so that the ratio β / α of the coil pitch β to the magnetic pole pitch α exceeds 1. Specifically, β / α is set to be greater than 1.00 (100%) and equal to or less than 1.25 (120%) (1.00<β / α≦1.25). In this case, the coreless motor 100 has, for example, a magnetic pole pitch α of 180 degrees, so the coil pitch β exceeds 180 degrees and is equal to or less than 225 degrees.

[0039] Here, the maximum torque T that the coreless motor 100 outputs due to the magnetic force acting on the conductor 61 of the coil 60 in the magnetic field of the magnet 30 is given by the following equation (1).

[0040] T = 2 * B * I * r * L * sin θ (1) In equation (1), B represents the magnetic flux from the magnet 30, I represents the current flowing through the coil 60, r represents the radius of the coil 60 (the dimension along the radial direction R), L represents the length of the coil 60 (the dimension along the direction of the center C), and θ represents the inclination angle of the conductor 61 in the coil 60 with respect to a plane perpendicular to the direction of the center C (90 degrees at the parallel portion 62, θ degrees at the upper oblique side portion 63, and θ degrees at the lower oblique side portion 64).

[0041] As a result, in the over-pitch coreless motor 100, the peak of the magnetic force of the magnet 30 acting on the parallel portion 62 decreases, but the magnetic flux acting on the oblique portions 63 and 64 at the angular position of the peak of the magnetic force increases, and as a result, the magnetic flux acting on the coil 60 as a whole increases, and the maximum torque T of the coreless motor 100 increases.

[0042] FIG. 7 is a graph showing the maximum torque T output by one turn of the wire 61 of the coil 60 when the ratio L1 / L0 of the length L1 of the parallel portion 62 to the total length L0 of the coil 60 is set to 0.25, 0.30, 0.35, 0.40, 0.45 (25, 30, 35, 40, 45 [%]) for each coil 60 and the ratio β / α of the coil pitch β to the magnetic pole pitch α is set to 0.95, 0.10, 1.05, 1.10, 1.25 (95, 100, 105, 110, 125 [%]).

[0043] However, Fig. 7 shows the maximum torque T output by a tortoiseshell-shaped coil 60 in which the oblique sides 63, 64 of the coil 60 are formed in an arc shape. In the case of a tortoiseshell-shaped coil in which the oblique sides 63, 64 of the coil 60 are formed in a straight line, the maximum torque T output by the coil is slightly reduced compared to the maximum torque T shown in Fig. 7, but the change in the maximum torque T with respect to the change in the ratio β / α is similar to that shown in the graph in Fig. 7.

[0044] In the graph shown in Figure 7, the coreless motor 100 of this embodiment is one in which the ratio L1 / L0 of the length L1 of the parallel portion 62 to the total length L0 of the coil 60 is set to 0.25, 0.30, 0.35, 0.40, 0.45 (25, 30, 35, 40, 45 [%]), and the ratio β / α of the coil pitch β to the magnetic pole pitch α is set to a range greater than 1.00 (100 [%]) and less than or equal to 1.25 (125 [%]).

[0045] The coreless motors 100 of the present embodiment are formed with an over-pitch, in which the coil pitch β is greater than the magnetic pole pitch α. As shown in FIG. 7 , when the ratio β / α of the coil pitch β to the magnetic pole pitch α is greater than 1.00 (100%) and less than 1.15 (115%), the coreless motor 100 of the present embodiment can increase the maximum torque T compared to a coreless motor with a non-over-pitch β = α (β / α = 100%). In particular, when the ratio β / α of the coil pitch β to the magnetic pole pitch α is greater than 1.05 (105%) and less than 1.10 (110%), the maximum torque T can be maximized. Therefore, in the coreless motor 100, it is preferable that the ratio β / α of the coil pitch β to the magnetic pole pitch α be within the above-mentioned range.

[0046] The upper limit of the ratio β / α of the coil pitch β to the magnetic pole pitch α is set to 1.25 (125%]) because if the ratio β / α becomes larger than this, it becomes difficult for the coreless motor 100 to output sufficient maximum torque T.

[0047] In the coreless motor 100 of these embodiments, the maximum torque T of the coreless motor 100 can be changed simply by setting the ratio β / α of the coil pitch β to the magnetic pole pitch α to greater than 100% without changing the size or strength of the coreless motor, such as by lengthening the dimension of the parallel portion 62 of the coil 60 in the coreless motor or increasing the number of turns of the wire in the coil 60.

[0048] In addition, by making the ratio β / α of the coil pitch β to the magnetic pole pitch α an over-pitch of more than 100%, the coreless motor 100 can not only change the maximum torque T of the coreless motor 100, but also change other characteristics of the coreless motor 100.

[0049] Specifically, the coreless motor 100 can reduce the rotation speed of the coreless motor 100, for example, by making the ratio β / α of the coil pitch β to the magnetic pole pitch α an over-pitch of more than 100%.

[0050] In the coreless motor 100 described above, the magnet 30 is formed with one north pole 30N and one south pole 30S. However, the magnet 30 in the coreless motor 100 of this embodiment may be formed with two north poles 30N and two south poles 30S. In this case, the magnetic pole pitch α is 90 degrees, and based on the conditional expression 1.00<β / α≦1.25 for the ratio β / α of the coil pitch β to the magnetic pole pitch α, the coil pitch β can be set to be greater than 90 degrees and less than or equal to 112.5 degrees.

[0051] In this case, in order to increase the maximum torque T, the coil pitch β should be set to be greater than 90 degrees and less than 103.5 degrees, based on the condition 1.00<β / α≦1.15 for the ratio β / α of the coil pitch β to the magnetic pole pitch α. In particular, in order to maximize the maximum torque T, the coil pitch β should be set to be greater than 94.5 degrees and less than 99 degrees, based on the condition 1.05≦β / α≦1.10 for the ratio β / α of the coil pitch β to the magnetic pole pitch α.

[0052] Similarly, the magnet 30 in the coreless motor 100 of this embodiment may be formed by forming n (3≦n) north poles 30N and south poles 30S, in which case the magnetic pole pitch α is 180 / n degrees, and based on the conditional equation 1.00<β / α≦1.25 for the ratio β / α of the coil pitch β to the magnetic pole pitch α, the coil pitch β can be set to be greater than 180 / n degrees and less than or equal to 225 / n degrees.

[0053] In this case, in order to increase the maximum torque T, the coil pitch β should be set to be greater than 180 / n degrees and less than 207 / n degrees, based on the condition 1.00<β / α≦1.15 for the ratio β / α of the coil pitch β to the magnetic pole pitch α. In particular, in order to maximize the maximum torque T, the coil pitch β should be set to be greater than 189 / n degrees and less than 198 / n degrees, based on the condition 1.05≦β / α≦1.10 for the ratio β / α of the coil pitch β to the magnetic pole pitch α.

[0054] As shown in FIG. 7, the coreless motor 100 of this embodiment can increase the maximum output torque T as the length ratio L1 / L0 increases. However, as the length ratio L1 / L0 increases, the cross-sectional area of ​​the conductor 61 in the direction perpendicular to the center C at the oblique side portions 63 and 64 increases, and as a result, the space factor of the conductor 61 at the parallel portion 62 decreases.

[0055] If the space factor of the conductor 61 in the parallel portion 62 becomes smaller than a predetermined value, the strength of the parallel portion 62 will decrease, and the centrifugal force acting when the coil 60 rotates around the center C will deform the coil 60, which may cause the coil 60 to come into contact with the housing 10. For this reason, the coil 60 needs to have a strength sufficient to prevent it from deforming at the rated rotation of the coreless motor 100.

[0056] As a result, in the coreless motor 100 of this embodiment, the upper limit of the length ratio L1 / L0 is set to 0.75 (75%), taking into account the required strength of the coil 60. In particular, in order to ensure a sufficient strength of the coil 60 while taking into account the safety factor at rated rotation, it is preferable to set the upper limit of the length ratio L1 / L0 to 0.45 (45%).

[0057] Furthermore, in the coreless motor 100 of this embodiment, the lower limit of the length ratio L1 / L0 of the coil 60 is set to 0.25 (25%), because this makes it easier for the coreless motor 100 to output the normally required minimum maximum torque T. If the length ratio L1 / L0 is less than 0.25 (25%), it becomes difficult for the coreless motor 100 to output a sufficient maximum torque T.

[0058] <Modification> Fig. 8 is a schematic diagram equivalent to Fig. 6 , showing a modification in which the coil pitch β is formed at a short pitch, where the coil pitch β is smaller than the magnetic pole pitch α (β<α). While the coreless motor 100 of the embodiment described above is formed at an over-pitch, where the coil pitch β is larger than the magnetic pole pitch α, as shown in Fig. 6 , the coreless motor according to the present invention is not limited to one having an over-pitch coil. In other words, a coreless motor according to a modification that is another embodiment of the present invention may be formed at a short pitch, where the coil pitch β is smaller than the magnetic pole pitch α (β<α), as shown in Fig. 8 , for example.

[0059] Specifically, in the modified coreless motor, the ratio β / α of the coil pitch β to the magnetic pole pitch α can be set to a range less than 1.00 (100%) (β / α<1.00), for example, a range greater than or equal to 0.90 (90%) and less than 1.00 (100%) (0.90≦β / α<1.00).

[0060] In the modified coreless motor configured in this manner, the ratio β / α of the coil pitch β to the magnetic pole pitch α is set to a short pitch of less than 1.00 (100%]), and the ratio β / α is set to a range of, for example, 0.90 (90%] or more and less than 1.00 (100%]), thereby allowing the characteristics of the coreless motor to be changed.

[0061] In the modified coreless motor, the ratio β / α of the coil pitch β to the magnetic pole pitch α is set to a short pitch of less than 1.00 (100%]), and the ratio β / α is set to a range of, for example, 0.90 (90%]) or more but less than 1.00 (100%]), thereby specifically, for example, increasing the rotation speed of the coreless motor.

[0062] Therefore, in a conventional coreless motor to which the present invention is not applied, when it is desired to increase the rotational speed by increasing the rotational speed, the rotational speed is increased by reducing the number of turns of the conductor 61 in the coil 60. However, reducing the number of turns of the conductor 61 in the coil 60 may result in a decrease in the rigidity of the coil 60.

[0063] In contrast, the coreless motor of the modified example does not reduce the number of turns of the conducting wire 61 in the coil 60, and therefore there is no possibility that the rigidity of the coil 60 will be reduced.

[0064] The coreless motor 100 in the above-described embodiment and modified example is an outer rotor type coreless motor in which the coil 60 is arranged outside the magnet 30, but the coreless motor according to the present invention is not limited to an outer rotor type coreless motor, and may be an inner rotor type coreless motor in which the coil 60 is arranged inside the magnet 30. In the case of an inner rotor type coreless motor, the outer peripheral surface of the magnet 30 is fixed to the inner peripheral surface of the case 11, for example.

[0065] The coreless motor according to the present invention is not limited to a coreless motor having a tortoise-shell shaped coil in which the hypotenuses 63, 64 of the coil 60 are formed in a straight line, but may also be a coreless motor having a tortoise-shell shaped coil in which the hypotenuses 63, 64 of the coil 60 are formed in a curved line (for example, a circular arc, an elliptical arc, or a parabola).

[0066] Furthermore, the coreless motor according to the present invention is not limited to a coreless motor having a tortoiseshell-shaped (hexagonal) coil, but may be a coreless motor having a coil of other shape (for example, diamond-shaped, square, circular, elliptical). In this coreless motor, the portions corresponding to the two parallel portions 62, 62 of the coil 60 are, for example, two vertices that face each other in the direction around the axis of the center C when the coil is diamond-shaped.

Claims

1. (Deleted)

2. (Deleted)

3. A rotating shaft, A coil formed in a cylindrical shape by winding a conducting wire and rotating integrally with the rotating shaft, A cylindrical magnet disposed inside or outside the cylindrical shape of the coil, and comprising: The angular interval β around the axis of the rotating shaft between the conducting wires in one turn of the coil is set to be larger than the angular interval α around the axis of the rotating shaft between the magnetic poles of the magnet, A coreless motor in which the ratio β / α of the angular interval β to the angular interval α is set to be greater than 1.00 and less than or equal to 1.

25.

4. The coreless motor according to claim 3, wherein the ratio β / α of the angular interval β to the angular interval α is set to be greater than 1.00 and less than or equal to 1.

15.

5. The coreless motor according to claim 3, wherein the ratio β / α of the angular interval β to the angular interval α is set to be greater than 1.00 and less than or equal to 1.

10.

6. The coreless motor according to claim 3, wherein the ratio β / α of the angular interval β to the angular interval α is set to be greater than or equal to 1.05 and less than or equal to 1.

10.

7. One turn of the coil has a parallel portion extending parallel to the axial direction of the rotating shaft, and two hypotenuse portions extending in a direction inclined at an angle with respect to a plane orthogonal to the axial direction and connected to both ends of the parallel portion, The coreless motor according to claim 3, wherein the ratio L1 / L0 of the length L1 of the parallel portion to the total length L0 of one turn of the coil along the axial direction of the rotating shaft is set to be greater than or equal to 0.25 and less than or equal to 0.

45.

8. (Deleted)