JP2012147622A - Coreless motor, robot hand mounted with coreless motor and robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coreless motor having high winding efficiency and high torque.SOLUTION: A coreless motor is configured by disposing a permanent magnet having a cylindrical shape inside a hollow air-core coil. Further, an air-core coil is formed by winding a cable therearound in a rhombus shape. Furthermore, one diagonal of the rhombus shape is set to be parallel with a central axis of the permanent magnet, and a length of the other diagonal is set to correspond to an angular range with an angle being 1.2 times through 1.6 times as large as an angle in which a magnetic pole of the permanent magnet is changed with respect to the central axis of the permanent magnet. Hereby, rotational torque of the coreless motor configuring the air-core coil by winding the cable therearound in the rhombus shape can be enhanced. In addition to the above, high winding efficiency thereof can be realized as a result that the cable is wound therearound in the rhombus shape.

Description

The present invention relates to a motor for generating rotational torque using electric power, and in particular, a coreless motor configured by combining a cylindrical air-core winding and a multi-pole magnetized permanent magnet provided inside thereof, And a robot hand or robot equipped with a coreless motor.

A coreless motor that rotates a rotor by switching the direction of the current that flows through the air-core winding is provided inside the air-core winding that is formed in a cylindrical shape. An inner rotor type coreless motor) is known. Alternatively, an outer rotor type coreless motor is also known in which an air-core winding is a rotor and a permanent magnet provided inside the rotor is a stator (for example, Patent Document 1). Since these coreless motors do not have a core, they have the advantage that the rotational inertia of the rotor is reduced and the responsiveness is improved, and further downsizing is relatively easy. Further, these coreless motors are based on the principle of generating rotational torque using Lorentz force received by a winding when a current is passed through the winding in a magnetic field formed by a permanent magnet.

Here, the Lorentz force acts in a direction perpendicular to the direction of the current (and hence the direction of the winding) as seen from the direction of the magnetic field. Therefore, in a portion where the direction of the winding is orthogonal to the direction of the rotation axis of the rotor, even if a Lorentz force is generated, it is directed to the direction of the rotation axis, so the Lorentz force cannot be converted into a rotation torque. That is, the portion of the winding that is orthogonal to the rotational axis of the rotor does not contribute to the generation of rotational torque, so that so-called winding efficiency is reduced. And
When the winding efficiency decreases, power consumption (so-called copper loss) due to electrical resistance increases, and the weight increases.

Therefore, a technique for winding a wire in a diamond shape has also been proposed. If the winding is wound in a rhombus shape, a portion orthogonal to the rotation axis of the rotor can be prevented from being generated, so that the winding efficiency can be improved (Patent Document 2).

JP 2007-236123 A JP 2007-124882 A

However, as with other types of motors, there is always a demand for higher torque in coreless motors. Therefore, it is desired to develop a coreless motor that has high winding efficiency and can generate high rotational torque. In particular, in order to be incorporated as a robot hand or a robot actuator, a small, efficient motor capable of generating a high torque is required, but there is a problem that such a motor does not exist.

The present invention has been made to solve at least a part of the above-described problems of the prior art, and aims to provide a coreless motor with high winding efficiency and capable of generating high rotational torque. To do.

In order to solve at least a part of the problems described above, the coreless motor of the present invention employs the following configuration. That is,
An air core winding formed into a hollow cylindrical shape by winding an electric wire, and a cylindrical permanent magnet provided on the inner peripheral side of the air core winding and having an outer peripheral surface magnetized in multiple poles; A coreless motor that generates rotational torque by passing a current through the air-core winding,
The permanent magnet is magnetized so that the polarity is alternately switched at intervals of a predetermined unit magnetic pole angle when viewed from the central axis of the permanent magnet,
The air-core winding is formed by bending a plurality of unit winding elements formed in a rhombus-like loop shape by shifting the position with respect to the central axis of the permanent magnet. Air core winding,
The rhombus shape of the unit winding element is such that one diagonal line is parallel to the central axis of the permanent magnet,
The other diagonal line has a rhombus shape having a length in the range of 1.2 to 1.6 times the unit magnetic pole angle with respect to the central axis of the permanent magnet.

In the coreless motor of the present invention having such a configuration, a cylindrical permanent magnet is provided inside an air core winding formed in a hollow cylindrical shape. The air-core winding is formed by providing a plurality of unit winding elements formed in a rhombus with a position shifted by a predetermined angle. In the rhombus shape of the unit winding element, one diagonal line is parallel to the central axis of the permanent magnet, and the other diagonal line has a unit magnetic pole angle of 1.2 with respect to the central axis of the permanent magnet.
The length is set to an angle range of double to 1.6 times.

Generally, in a coreless motor that forms an air-core winding by winding an electric wire in a rhombus shape, the length of the diagonal line that is perpendicular to the central axis of the permanent magnet (diagonal line in the rotation direction) is
The unit magnetic pole angle is set with respect to the central axis of the permanent magnet. However, by extending the length of the diagonal line in the rotational direction, there is a possibility that the rotational torque of the coreless motor having the air-core winding wound in a rhombus shape may be improved. As will be described in detail later, the length of the diagonal line in the rotation direction is 1.2 times 1.6 to 1.6 times the unit magnetic pole angle with respect to the central axis of the permanent magnet. It has been found that if the length is set to be a double angle range, the rotational torque can be improved. Therefore, by doing in this way, it is possible to realize a coreless motor having high winding efficiency and capable of generating high rotational torque.

In the above-described coreless motor of the present invention, when a N-phase current (where N is an integer of 2 or more) is passed through the air-core winding, the plurality of unit winding elements are arranged at the center of the permanent magnet. By shifting the position by an angle corresponding to 1 / N of the unit magnetic pole angle with respect to the axis,
An air core winding may be formed.

In this way, by uniting the winding elements provided by shifting the position by the unit magnetic pole angle, a plurality of unit winding elements can be divided into N phases. A plurality of unit winding elements are
If the drive is divided into phases, the fluctuation of the rotational torque of the coreless motor can be reduced.

The coreless motor of the present invention described above is particularly excellent as a motor used by being incorporated in a robot hand or a robot because it has high winding efficiency and can generate high torque.

It is explanatory drawing which showed the external appearance shape of the coreless motor of a present Example. It is explanatory drawing which showed the structure of the air core winding of the coreless motor of a present Example. It is explanatory drawing which shows the operation principle of a general coreless motor. It is explanatory drawing shown about the merit and demerit of the conventional rhombus winding. It is explanatory drawing which showed the premise for calculating the rotational force obtained with the unit winding element of a present Example. It is explanatory drawing which shows the derivation | leading-out process of the rotational force which the unit winding element of a present Example generate | occur | produces. It is explanatory drawing which showed the change of the rotational force obtained when a unit winding element is moved. It is explanatory drawing which shows the rotational force obtained by the coreless motor of a present Example. It is explanatory drawing which showed the relationship between the length of the diagonal of the rotation direction of a unit winding element, and the average value of rotational force. It is explanatory drawing which illustrated a mode that the coreless motor of a present Example was integrated in the joint part of the robot hand. It is explanatory drawing which illustrated a mode that the coreless motor of a present Example was integrated as an actuator of a robot.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Structure of coreless motor of this embodiment:
B. Coreless motor operating principle:
C. Rotational force obtained with the coreless motor of this embodiment:
D. Application example:

A. Coreless motor structure of this embodiment:
FIG. 1 is an explanatory view showing the structure of the coreless motor 100 of this embodiment. FIG.
As shown in the figure, the coreless motor 100 of this embodiment includes a cylindrical permanent magnet 120 accommodated inside a cylindrical air-core winding 110, and a rotating shaft 122 coaxially with the central axis of the permanent magnet 120. Is provided. The permanent magnet 120 is magnetized so that the N pole and the S pole are alternately switched at an equal angle from the central axis. The air-core winding 110 is formed by being formed into a hollow cylindrical shape by winding an electric wire and then being hardened with a resin.

As is apparent from the fact that the rotating shaft 122 is provided on the permanent magnet 120, the coreless motor 100 of this embodiment is a so-called inner rotor in which the permanent magnet 120 serves as a rotor and the air-core winding 110 serves as a stator. A coreless motor 100 of the type. Of course, the configuration is not limited to this, and the coreless motor 100 of the so-called outer rotor type can be configured by providing the rotating shaft 122 in the air-core winding 110.

FIG. 1B is an explanatory diagram showing a state in which the bottom surface of the coreless motor 100 of this embodiment is viewed from the direction of the rotating shaft 122. As will be described in detail later, the coreless motor 100 of the present embodiment.
The air-core winding 110 is formed by stacking unit coils 112 formed by winding an electric wire many times in a rhombus shape while shifting the position by a predetermined angle. The angle by which the unit coil 112 is shifted is set to an angle that is half of the angle at which the magnetic poles are switched at equal angular intervals by the permanent magnet 120 (hereinafter referred to as the unit magnetic pole angle).

FIG. 2 is an explanatory view showing the structure of the air-core winding 110 of the present embodiment. As described above, the air core winding 110 is formed in a hollow cylindrical shape surrounding the periphery of the permanent magnet 120. For convenience of understanding, however, in FIG. 110 and permanent magnet 120
Is displayed on a flat surface. As shown in FIG. 2A, the unit coil 1
12 is formed in a substantially rhombus shape, and the air-core winding 110 is formed by overlapping the rhombus-shaped unit coils 112 while shifting their positions by equal distances. In FIG. 2, the cylindrical air core winding 110 is displayed in a state of being developed on a plane. Therefore, it is actually the case that the unit coils 112 are displaced by the same “distance” on the drawing of FIG. 2. This corresponds to the fact that the position of each air core winding 110 is shifted by the same “angle”.

Further, in the coreless motor 100 of the present embodiment, the plurality of unit coils 112 are divided into two groups, and the unit coils 112 of the same group are formed by winding a series of electric wires. Hereinafter, one group is referred to as “a phase” and the other group is referred to as “b phase”. These a-phase unit coils 112a and b-phase unit coils 112b are alternately stacked. That is, the b-phase unit coil 112b is overlapped on the a-phase unit coil 112a by shifting the position by a predetermined distance (angle), and the position is set on the b-phase unit coil 112b by a predetermined distance (angle). Staggered a-phase unit coil 11
The a-phase unit coil 112a and the b-phase unit coil 112 are overlapped, such as 2a.
b and are alternately stacked. 2B or 2C, only the a-phase unit coil 112a or only the b-phase unit coil 112b is extracted from the plurality of unit coils 112 constituting the air-core winding 110. It is shown. As described above, the a-phase unit coil 112a and the b-phase unit coil 112b are provided with their positions shifted by half the unit magnetic pole angle of the permanent magnet 120. Since the a-phase unit coils 112a and the b-phase unit coils 112b are provided alternately, the a-phase unit coils 112a or the b-phase unit coils 112b are positioned at unit magnetic pole angles. It will be provided by shifting.

Here, the a-phase or b-phase unit coil 112 is formed by winding a single electric wire many times in a diamond shape. Below, the wire wound only once in the rhombus shape,
This will be referred to as “unit winding element 114”. The diamond-shaped unit winding element 114 has two diagonal lines in the left-right direction (that is, the rotation direction of the permanent magnet 120) and the direction orthogonal to the left-right direction on the paper surface of FIG. In the coreless motor 100 of the present embodiment, FIG.
), The length of the diagonal line in the rotation direction of the permanent magnet 120 (actually, the angle range) is 1 of the unit magnetic pole angle (indicated as p in the figure) at which the polarity of the permanent magnet 120 switches. .2
Double to 1.6 times are set. By doing in this way, the coreless motor 1 of the present embodiment.
At 00, the winding efficiency is high and a high rotational torque can be generated. Hereinafter, this point will be described in detail.

B. Coreless motor operating principle:
First, the operation principle of a general coreless motor will be briefly described. FIG.
These are explanatory drawings showing the operating principle of a general coreless motor. In a typical coreless motor, the electric wire is wound in a rectangle instead of a diamond shape. FIG. 3 shows a unit winding element 116 wound in a rectangular shape. The length of the short side (in practice, the angle range) of the unit winding element 116 is set to be the same as the unit magnetic pole angle p of the permanent magnet 120.

When the unit winding element 116 is in a positional relationship as shown in FIG. 3A with respect to the magnetic pole of the permanent magnet 120, a current in the direction indicated by the broken line is passed through the unit winding element 116. Then
According to Fleming's left-hand rule, the unit winding element 116 is subjected to Lorentz force in the direction indicated by the white arrow in the drawing. Here, the unit winding element 116 does not move because it is on the stator side. For this reason, the permanent magnet 120 receives a reaction and rotates. Black arrows shown in the figure indicate the rotation direction of the permanent magnet 120.

Further, when the permanent magnet 120 rotates, as shown in FIG.
The direction of the magnetic field exerted on is reversed. Therefore, if the current continues to flow in the same direction, the direction of the Lorentz force is reversed and the permanent magnet 120 cannot continue to rotate. Therefore, in such a case, the direction of the current flowing through the unit winding element 116 is reversed. In this way, even if the direction of the magnetic field exerted on the unit winding element 116 is reversed, the direction of the Lorentz force can be kept the same, so that the rotation of the permanent magnet 120 can be continued. Thus, in the coreless motor, by switching the direction of the current according to the rotation of the permanent magnet 120,
Lorentz force acting on the unit winding element 116 is converted into rotational torque.

Here, as can be understood from FIG. 3, the unit winding element 11 can be converted into rotational torque.
6 is a portion facing the direction along the rotation axis (in the example shown in FIG. 3, the portion corresponding to the long side of the rectangle). Since the magnetic field of the permanent magnet 120 does not act on the short side portion of the rectangle, Lorentz force does not occur, or even if Lorentz force acts, it acts in the direction along the rotation axis and cannot be converted into rotational torque. Therefore, such a portion in the unit winding element 116 merely becomes a resistance even when a current is passed, and the winding efficiency is greatly reduced. If the unit winding element 116 has a diamond shape, such a problem does not occur. On the other hand, when the unit winding element 116 has a rhombus shape, another problem is concerned.

FIG. 4 is an explanatory diagram for explaining the advantages and disadvantages of the diamond-shaped unit winding element 114. As shown in the figure, in the conventional diamond-shaped unit winding element 114, the diagonal length (actually in the horizontal direction in the figure) of the permanent magnet 120 among the two diagonal lines of the rhombus Angle range) is set to be the same as the unit magnetic pole angle p of the permanent magnet 120.

First, as a merit by the diamond-shaped unit winding element 114, for example, FIG.
As can be seen from the above, in the diamond-shaped unit winding element 114, it is possible to generate a rotational torque in all parts, and the winding efficiency is greatly improved. Further, when the boundary of the magnetic poles of the permanent magnet 120 is at the center of the rhombus, a rotational torque equivalent to that of the rectangular unit winding element 116 shown in FIG. 3 can be obtained.

However, when the boundary between the magnetic poles of the permanent magnet 120 is not at the center of the rhombus shape, the rotational torque decreases. This is a disadvantage of the diamond-shaped unit winding element 114. For example, FIG.
In the example shown in (b), the direction of the magnetic field is reversed halfway along the left side of the rhombus in the drawing. For this reason, on the left oblique side, the direction of the Lorentz force is reversed in the middle, and as a result of trying to cancel the rotational torque, the rotational torque is reduced.

Therefore, the inventors of the present application, as shown by a thin broken line in FIG.
The idea was that the decrease in rotational torque could be compensated by extending the length of the diagonal line in the left-right direction (rotation direction). And after obtaining such an idea, as a result of adding a detailed study as described below, the present invention was completed by finding new knowledge.

C. Rotational force obtained with the coreless motor of this embodiment:
FIG. 5 is an explanatory diagram showing preconditions for calculating the rotational force obtained by the unit winding element 114 of the present embodiment. As shown in FIG. 5 (a), the length of the diagonal line of the rhombic shape of the unit winding element 114 (actually corresponding to the angle range) is “u”, and the vertical direction (rotation axis) The length of the diagonal line of “direction” is “v”, and the length of the hypotenuse is “d”. In addition, the permanent magnet 120
An angle range (unit magnetic pole angle) at which the magnetic poles of the magnetic poles are switched is defined as “p”. Furthermore, the distance from the boundary where the magnetic pole of the permanent magnet 120 is switched to the center of the rhombus shape of the unit winding element 114 is “t”. In this case, the shape of the unit winding element 114 is represented by the variable u indicating the length of the diagonal line in the left-right direction (rotation direction), and the position of the unit winding element 114 is determined from the boundary of the magnetic pole of the permanent magnet 120 by the unit. This is represented by a variable t indicating the distance to the center of the winding element 114.

In addition, there are two states in which the magnetic field of the permanent magnet 120 exerts on the unit winding element 114. That is, while the value of the variable t is small, as shown in FIG. 5B, the direction of the magnetic field is changed halfway along the left oblique side of the unit winding element 114, but the direction of the magnetic field is changed along the right oblique side. The state is not switched (hereinafter referred to as the first state). Further, when the value of the variable t increases, as shown in FIG. 5C, the state of the magnetic field switching in the middle of any of the left and right hypotenuses of the unit winding element 114 (hereinafter, (Referred to as the second state). In the first state, the length of the portion where the magnetic field is reversed is “d2”, and the length of the portion where the magnetic field is not reversed is “
d1 ". In the second state, the length of the portion where the magnetic field is reversed is set to “d2” and “
d4 ”and the lengths of the non-reversed portions are“ d1 ”and“ d3 ”.

By the way, the direction of the magnetic field is switched in the middle of the right side of the unit winding element 114, and the direction of the magnetic field is switched on the left side of the unit winding element 114. The state that does not change can be considered as a case where the variable t takes a negative value in the first state.
Further, the state where the boundary of the magnetic pole passes through the center of the unit winding element 114 is the first state, and the variable t is “0”.
Can be considered as the case.

First, the first state shown in FIG. In the first state of FIG.
Since the direction of the magnetic field is reversed in a part of the left hypotenuse, the Lorentz force acts in the opposite direction in this part. Accordingly, in the upper left hypotenuse of the unit winding element 114 (hereinafter, this hypotenuse is referred to as the first side), the Lorentz force F1 in the positive direction is perpendicular to the hypotenuse in the part where the direction of the magnetic field is not reversed. And a Lorentz force f1 in the negative direction is applied to the portion where the direction of the magnetic field is reversed at a right angle to the hypotenuse. Note that the Lorentz force of a small letter f represents a Lorentz force in the negative direction (direction to cancel the rotational torque), and the Lorentz force of a capital letter F represents a Lorentz force in the positive direction (a direction in which the rotational torque is increased). . Similarly, a positive Lorentz force F2 and a negative Lorentz force f2 also act on the lower left hypotenuse of the unit winding element 114 (hereinafter, this hypotenuse is referred to as the second side). Further, the lower right hypotenuse (hereinafter, this hypotenuse is referred to as the third side) and the upper right hypotenuse (hereinafter, this hypotenuse is referred to as the fourth side) of the unit winding element 114 are respectively positive Lorentz. Forces F3 and F4 act. Therefore, the component of the rotation direction (left-right direction in the drawing) of these Lorentz forces acting on the first side to the fourth side of the unit winding element 114 becomes the rotation force converted into the rotation torque. In particular, the positive Lorentz force F
The components in the rotational direction of 1 to F4 are rotational forces that increase the rotational torque, and the rotational direction components of the negative Lorentz forces f1 and f2 are rotational forces that decrease the rotational torque. In the following, the rotational direction component of the Lorentz force is described with the suffix x. For example,
F1x represents the rotational direction component of the Lorentz force F1.

The same is true for the second state shown in FIG. That is, positive Lorentz forces F1 to F4 and negative Lorentz forces f1 to f4 act on the first side to the fourth side of the unit winding element 114, and the rotational direction components of these Lorentz forces rotate. It becomes power. Note that in FIG. 5C, only the components in the rotational direction of the respective Lorentz forces are displayed in order to avoid complicated illustration.

Based on the above examination, the rotational force F obtained by one unit winding element 114 is set to the first state,
Derived for each of the second states. FIG. 6 is an explanatory diagram showing the process of deriving the rotational force F. FIG. 6 (a) shows a process for deriving the rotational force F in the first state, and FIG. 6 (b) shows a process for deriving the rotational force F in the second state. “B” in the figure represents the strength of the magnetic field,
“I” represents a current flowing through the unit winding element 114.

First, a process for deriving the rotational force F in the first state shown in FIG. 6A will be briefly described. The first state is when t + u / 2 <p holds. For simplicity, considering only the case where t is greater than or equal to 0, the first state is that the value of the variable t is 0 ≦ t <(p
-U / 2).

Also, according to Fleming's left-hand rule, the Lorentz force acting per unit length is
It is proportional to the magnetic field strength B and the current I. Accordingly, the positive Lorentz force F1 acting on the first side is a value d1 · B · I obtained by multiplying the length d1 of the wire by B and I, and the component F1x in the rotational direction is its cosine component (d1 · B · I · cos θ). Similarly, in the rotational direction components F2x to F4x of the positive Lorentz force acting on the other three sides, (d1 ·
B · I · cos θ), (d · B · I · cos θ), and (d · B · I · cos θ). And the value which totaled these becomes the rotational force of a positive direction.

Further, the rotation direction component f1x of the negative Lorentz force acting on the first side is a cosine component obtained by multiplying the length d2 of the electric wire by B and I. Therefore, (d2 · B · I · cos θ ) Similarly for the second side, f2x is (d2 · B · I · cos θ). Note that FIG.
As shown in (b), in the first state, the Lorentz force in the negative direction does not act on the third side and the fourth side. Therefore, f3x and f4x are “0”. And the sum of these values is
Negative rotational force. Eventually, in the first state, the rotational component of the Lorentz force acting on the unit winding element 114 (that is, the rotational force) is obtained by subtracting the negative rotational force from the positive rotational force. B · I · v · (1-2t / u).

The rotational force F in the second state can be derived in the same manner. First, the second state is the variable t
Is larger than (p−u / 2) and smaller than (u / 2), that is, (p−
This is a case where u / 2) ≦ t <(u / 2). Further, the positive Lorentz forces F1 to F4 acting on the first side to the fourth side, the negative Lorentz forces f1 to f4, and the components in the rotation direction thereof can be obtained in the same manner. As a result, in the second state, the unit winding element 1
14 is obtained by subtracting a negative rotational force from a positive rotational force, and 2 · B · I · v · (2p / u). -4
t / u).

FIG. 7 shows a unit winding element 114 in which the length of the diagonal line in the rotation direction (left-right direction in the figure) is “u”.
It is the graph which showed the rotational force F obtained when this is moved with respect to the permanent magnet 120. FIG.
On the horizontal axis of the graph, a variable t indicating the position of the unit winding element 114 with respect to the permanent magnet 120 is taken. When the variable t is in the range of 0 to (p−u / 2), the unit winding element 114 is in the first state. Therefore, as described above with reference to FIG. 2 ・ B ・ I ・ v ・
It is calculated by (1-2t / u). Further, when the variable t is in the range of (p−u / 2) to (u / 2), the unit winding element 114 is in the second state, and as described above with reference to FIG. The rotational force F is obtained by 2 · B · I · v · (2p / u-4t / u). The solid line shown in FIG. 7 represents the rotational force F obtained in this way.

Further, when the unit winding element 114 moves in the opposite direction with respect to the permanent magnet 120 (that is, when the variable t has a negative value), the rotational force F indicated by the solid line is t = You can think of it as inverted around zero. The thick broken line shown in FIG. 7 represents the rotational force F obtained in this way. Further, the unit winding element 114 has a unit magnetic pole angle p of the permanent magnet 120.
The direction of the magnetic field acting on the unit winding element 114 is reversed, but the direction of the current passed through the unit winding element 114 is also reversed, so that the unit winding element 114 eventually becomes a unit magnetic pole angle. The same is true even if only p is moved. Accordingly, the rotational force F indicated by a thin broken line in FIG. 7 is generated.

As described above with reference to FIG. 2B, the a-phase unit coils 112a are provided apart from each other by the unit magnetic pole angle p. Therefore, the rotational force F shown in FIG. It can be considered that the rotational force F obtained by the unit coil 112a is shown. Further, regarding the b-phase unit coil 112b, it can be considered that the same thing is true for the rest, except that the unit coil 112b is shifted by half the unit magnetic pole angle p with respect to the a-phase unit coil 112a.
Then, the rotational force F obtained by the a-phase unit coil 112a and the b-phase unit coil 11 are obtained.
The total value of the rotational force F obtained in 2b is the rotational force F generated by the air-core winding 110 of the coreless motor 100, and the value obtained by multiplying the rotational force F by the rotational radius is the coreless motor 1.
The rotation torque is 00.

FIG. 8 is an explanatory diagram showing the rotational force F obtained by the coreless motor 100 of the present embodiment. 8A shows the rotational force Fa obtained by the a-phase unit coil 112a, and FIG. 8B shows the rotational force Fb obtained by the b-phase unit coil 112b. still,
Since the unit coil 112 is wound with an electric wire many times and is composed of a plurality of unit winding elements 114, the actual rotational force obtained by the unit coil 112 is the respective rotational force Fa, Fb. The value obtained by multiplying the unit coil 112 by the number n of times the wire is wound. However, in order to avoid complicated description, the following description will be made assuming that n = 1.

The rotational force F generated by the air-core winding 110 is the sum of the rotational force Fa obtained by the a-phase unit coil 112a and the rotational force Fb obtained by the b-phase unit coil 112b. The waveform shown in (c) is obtained. As shown, the total rotational force F is
Between 2 · B · I · v and 8 · B · I · v · (1−p / u), the waveform varies with a period of p / 2.

At the timing when the a-phase rotational force Fa shown in FIG. 8 (a) is minimized, the b-phase rotational force Fb shown in FIG. 8 (b) is maximized, and conversely in FIG. 8 (b). At the timing at which the b-phase rotational force Fb is minimized, the a-phase rotational force Fa illustrated in FIG. 8A is maximized. For this reason, in the rotational force F obtained by summing the a-phase rotational force Fa and the b-phase rotational force Fb, the fluctuation range is smaller than the respective rotational forces Fa and Fb.

When the average rotational force Fave of the rotational force F obtained in this way is obtained, 2 · B · I · v
(4-u / p-2 · p / u) is obtained. The obtained calculation formula includes a variable u indicating the length of the diagonal line in the rotation direction of the unit winding element 114. Therefore, the average rotational force Fave increases or decreases depending on how the variable u is taken.

Further, as described above with reference to FIG. 4B, in the conventional coreless motor in which the winding is wound in a diamond shape, the length of the diagonal line in the rotation direction of the diamond shape corresponds to the unit magnetic pole angle p. The present invention intends to improve the rotational torque by extending this length. Therefore, paying attention to the range where the variable u is equal to or larger than the unit magnetic pole angle p, the behavior of the average rotational force Fave will be examined.

FIG. 9 is an explanatory diagram showing how the average rotational force Fave changes when the length u of the diagonal line in the rotational direction of the unit winding element 114 is changed. For reference, even when the variable u takes a value smaller than the unit magnetic pole angle p, it is indicated by a broken line. As shown by a solid line in FIG. 9, the average rotational force Fave becomes the maximum value when the variable u takes a value that is a square root multiple of 2 with respect to the unit magnetic pole angle p. That is, if the length u of the diagonal line in the rotational direction of the unit winding element 114 having a rhombus shape is set to a square root of 2 with respect to the length corresponding to the unit magnetic pole angle p of the permanent magnet 120, It becomes possible to make the rotational torque of the coreless motor 100 the highest.

However, the actual unit winding element 114 cannot be formed in a complete rhombus shape as shown in FIG. Further, the strength of the magnetic field formed by the permanent magnet 120 is also weak near the boundary where the polarity is switched. Due to these effects, the highest rotational torque in the actual unit winding element 114 may vary somewhat from the square root of 2 times. In addition, even if the rotational torque is slightly different from the highest condition, it can be considered that the rotational torque is still greatly improved as compared with the coreless motor in which the winding is wound in a conventional diamond shape. Considering these elements, the length u of the diagonal line in the rotational direction of the diamond-shaped unit winding element 114 is set as the permanent magnet 1.
If the length corresponding to 20 unit magnetic pole angles p is set within a range of about 1.2 to 1.6 times, the rotational torque of the coreless motor 100 can be greatly improved. . Of course, even in this case, since the unit winding element 114 has a rhombus shape, the winding efficiency does not decrease. As a result, the coreless motor 100 of this embodiment has high winding efficiency and can generate high rotational torque.

D. Application example:
The coreless motor 100 of the present embodiment described above has excellent characteristics that the winding efficiency is high and high rotational torque can be generated while maintaining the advantage of the coreless motor that the response is high. For this reason, the coreless motor 100 of the present embodiment is particularly suitable as a coreless motor for use in a robot hand joint.

FIG. 10 is an explanatory view exemplifying a state in which the coreless motor 100 of this embodiment is incorporated in the joint portion of the robot hand 200. The illustrated robot hand 200 has two fingers 2
02 are provided to face each other, and each finger 202 has 3 including the root.
There are two joints. Since the coreless motor 100 of this embodiment has high responsiveness and can generate high torque, the joint can be moved smoothly. In addition, since the winding efficiency is high, power loss (so-called copper loss) in the coreless motor 100 can be suppressed, which is particularly suitable for such applications.

FIG. 11 is an explanatory view illustrating the state in which the coreless motor 100 of this embodiment is incorporated as an actuator of the robot 500. As described above, the coreless motor 100 of the present embodiment has excellent characteristics such as high responsiveness and power efficiency and high torque output. For this reason, by using the coreless motor 100 of this embodiment as an actuator, a high-performance robot 500 can be configured.

The coreless motor of the present embodiment and the modification has been described above, but the present invention is not limited to all the embodiments and modifications described above, and can be implemented in various modes without departing from the scope of the present invention. It is.

For example, in the above-described embodiments and modifications, the coreless motor 100 has been described as a two-phase motor of a phase and b phase. However, any coreless motor 10 having three or more phases may be used.
The present invention can be preferably applied to 0.

100: Coreless motor, 110: Air core winding, 112 ... Unit coil,
114: Unit winding element, 116: Unit winding element, 120 ... Permanent magnet,
122 ... Rotating axis 200 ... Robot hand 202 ... Finger
500 ... Robot, p ... Unit magnetic pole angle

Claims (4)

An air core winding formed into a hollow cylindrical shape by winding an electric wire, and a cylindrical permanent magnet provided on the inner peripheral side of the air core winding and having an outer peripheral surface magnetized in multiple poles; A coreless motor that generates rotational torque by passing a current through the air-core winding,
The permanent magnet is magnetized so that the polarity is alternately switched at intervals of a predetermined unit magnetic pole angle when viewed from the central axis of the permanent magnet,
The air-core winding is formed by bending a plurality of unit winding elements formed in a rhombus-like loop shape by shifting the position with respect to the central axis of the permanent magnet. Air core winding,
The rhombus shape of the unit winding element is such that one diagonal line is parallel to the central axis of the permanent magnet,
A coreless motor having a rhombus shape having a length in which the other diagonal line is in the range of 1.2 to 1.6 times the unit magnetic pole angle with respect to the central axis of the permanent magnet. The coreless motor according to claim 1, wherein a rotational torque is generated by flowing an N-phase current (where N is an integer of 2 or more) through the air-core winding,
The air-core winding has an air-core winding in which the plurality of unit winding elements are displaced from each other by an angle corresponding to 1 / N of the unit magnetic pole angle with respect to the central axis of the permanent magnet. Coreless motor that is a wire.   A robot hand equipped with the coreless motor according to claim 1.   A robot equipped with the coreless motor according to claim 1.

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