JP2981546B1 - Brushless DC servo motor - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To obtain a high torque output in a low speed rotation region,
Provided is a brushless DC servomotor capable of increasing the rotation speed in a low-load high-speed rotation region. SOLUTION: Coil springs 9a to 9d are pulled inside a rotor unit 2 rotatably provided in a magnetic field of three coils L1 to L3 controlled by a control circuit 3 in a direction against centrifugal force. The first to fourth movable members 8a to 8d made of a high magnetic permeability material are provided, and the centrifugal force against the tension of the coil springs 9a to 9d acts to produce the first to fourth movable members.
When the fourth movable members 8a to 8d move so as to close the gaps 7a to 7d, the magnetic flux guides 6a and 6b made of a high magnetic permeability material magnetically coupled to the magnetic poles of the permanent magnet 2a and the magnetic flux guide path in the rotor. The gap between the formed bodies 6c and 6d is filled with a high magnetic permeability material, and a magnetic path is formed in the rotor unit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor having a permanent magnet rotatable around a rotation axis, and a stator having three or more coils arranged around the rotor. The present invention relates to a brushless DC servomotor that rotates a rotor by changing a magnetic field acting on both magnetic poles of a permanent magnet of a rotor by controlling power supply to the rotor.

[0002]

2. Description of the Related Art A conventional brushless DC servomotor has nine
As shown in the figure, a brushless servomotor 101
Are three sets of coils L1, L2, L3 fixed to the case.
And a rotor 102 made of permanent magnets
The magnetic pole position of the permanent magnet as the rotor 102 is detected by a sensor (not shown) such as a Hall element.
The control circuit 103 controls the power supply to the coils L1 to L3 in accordance with the magnetic pole position of the permanent magnet, thereby generating an attractive force or a repulsive force with the rotor 102, and
It keeps generating a force to rotate in a certain direction.

The operating principle of a brushless DC servomotor is the so-called "Fleming's left-hand rule" in which when a current flows through a conducting wire in a magnetic field, a force proportional to the product of the magnetic field and the current is generated. The torque τ generated by the motor is determined by the magnetic flux density B created by the permanent magnet of the rotor,
It can be calculated from the current i flowing through the coil by the following equation.

[0004] _{τ = k t × B × i} ... (1)

[0005] The above (1) k _t in the formula is a constant determined by the turns and the shape of the coil of the motor.

On the other hand, when the motor is rotating, a voltage proportional to the rotation speed is generated at both ends of the coil (Fleming's right-hand rule). This represents the action of the motor as a generator, and the voltage E generated at both ends of the coil can be calculated by the following equation from the magnetic flux density B generated by the permanent magnet of the rotor and the rotational speed ω of the rotor.

E = k _e × B × ω (2)

[0008] k _e in equation (2) is a constant determined by the turns and the shape of the coil of the motor.

The above is the basic principle of the brushless DC servomotor, and all the various characteristics of the motor can be derived from equations (1) and (2).

Here, as shown in FIG. 10, if a power supply of a voltage V is connected to the motor M and the motor M is rotating at a rotation speed ω, the resistance of the coil of the motor M is set to R, and Ohm's law and the above From the equation (2), the current i flowing through the coil can be calculated as in the following equation.

[0011] i = (V-E) / R = (V-k e Bω) / R ... (3)

From the relation between the current i and the torque τ in the above equations (3) and (1), the relation between the torque τ and the rotation speed ω is obtained as in the following equation.

[0013] _{τ = k t B (V-} k e Bω) / R ... (4)

In the above equation (4), if the rotational speed ω is expressed as a function of the torque τ, the following equation is obtained.

[0015] _{ω = V / k e B- (} R / k t k e B 2) τ ... (5)

When the above equation (5) is displayed as a characteristic diagram,
As shown in FIG. This represents the relationship between the load and the rotation speed of the motor M to which a constant voltage V is applied. In detail, the maximum torque τ motor M may occur a k _t BV / R, the rotational speed at this time the motor M is zero (point in Fig. 11 a). Then, as the load torque τ decreases, the rotation speed ω increases, and the load torque τ becomes zero.
Motor M rotates at the maximum speed V / k _e B when (FIG. 1
Point b) at 1. Thus, the maximum speed ω _max at which the motor M can rotate under a constant voltage V is equal to the load torque τ
Is set to 0, and is determined by the following equation.

Ω _max = V / k _e B (6)

That is, as long as the conventional motor M is driven by the given power supply voltage V, it is impossible to obtain a higher rotation speed. Particularly, in recent years, rare-earth magnets have been used for the rotor in order to obtain a larger torque τ, and the magnetic flux density B has increased. Therefore, it has become more difficult to increase the maximum rotation speed ω _max .

For this reason, in order to increase the maximum rotation speed of the motor M, a method of driving the motor M with a higher power supply voltage is conceivable. However, the danger of electric shock or the like increases because the power supply voltage increases. Therefore, it is not preferable. Therefore, a motor mechanism that switches the rotation speed of the motor using a transmission has been proposed.

FIG. 1 shows an example of a motor mechanism using a transmission.
As shown in FIG. 2, the first drive shaft 104 of the motor M is
A drive gear 105a and a second drive gear 105b are attached, and a first driven gear 108 is attached to a driven shaft 107 of the load 106.
a and the second driven gear 108b are attached, and in a low-speed region where the load 106 is rotated at the rotation speed of the motor M,
In a high-speed region where the first drive gear 105a and the first driven gear 108a having a gear ratio of 1: 1 mesh with each other (see FIG. 12A) and the load 106 rotates at a high speed, the gear ratio is n: 1. Second driving gear 105b and second driven gear 1
08b (see FIG. 12B).

That is, when a large torque is required at the time of starting a load or during an accelerating operation, the gear ratio is set to 1: 1. At a high-speed operation that does not require a large torque, the gear ratio becomes n: 1. The gear should be changed so that

FIG. 13 shows a characteristic diagram of the torque and the number of revolutions of the motor mechanism using the above-described transmission. For example, the motor M connected to the load at a gear ratio of 1: 1 is started. When the gear is switched at a point b where the rotational speed gradually increases from the point a and the load torque decreases, the gear ratio changes to n: 1, and the gear shifts to the point c, where the load torque becomes zero. The number of rotations of d can be increased. That is, although the characteristics of the motor M itself are the same, the output characteristics of the motor mechanism can be changed by switching the gear between low-speed rotation and high-speed rotation.

[0023]

However, in the motor mechanism for increasing the maximum rotation speed using the above-described transmission, a complicated transmission mechanism is required in addition to the motor. It cannot be used in fields where small size and light weight are required. In particular, it is not preferable as a mechanism of a brushless DC servomotor mounted on a drive system or the like of a robot that requires quick start / stop control and high-speed operation.

Therefore, the present invention automatically increases the maximum rotation speed from a low-speed rotation state with a large load torque to a high-speed rotation state with a reduced load torque without using a heavy and bulky drive mechanism. It is an object of the present invention to provide a brushless DC servomotor capable of automatically generating a large torque when a low-speed rotation state with a large load torque is changed from a high-speed rotation state in which the load is reduced.

[0025]

According to a first aspect of the present invention, there is provided a brushless DC servo motor having a rotor (for example, a rotor) that is capable of rotating a permanent magnet (20a) around a rotation axis (20b). A rotor unit 20) and a stator in which three or more coils (L1, L2, L3) are arranged around the rotor. By controlling power supply to each coil of the stator, the permanent magnet varying the magnetic field acting on the magnetic poles of the brushless DC servo motor for rotating the rotor (1 0), the flux guide forming a flux guide for guiding the magnetic flux from the magnetic poles of the permanent magnets provided in the rotor to the rotor outside Means for guiding the magnetic flux to the outside of the rotor due to the centrifugal force that increases as the rotation speed of the rotor increases, and the flux guiding means disappears and becomes inactive.

Further, the brushless DC servo motor according to claim 2, as a flux guide means of claim 1, the magnetic fluid
Magnetic material-filled space filled with magnetic material with fluidity such as
(For example, the first and second magnetic substance enclosed cavities 21a and 21b)
Is formed in the rotor, and a magnetic material of a permanent magnet is
The magnetic pole adsorbed by the magnetic pole of the permanent magnet
The body (22) gathers in the direction of magnetic flux outflow, and the magnetic poles of the permanent magnet
The magnetic flux guide path that guides the magnetic flux from the rotor to the outside of the rotor
It is formed inside the part and increases with the rotation speed of the rotor.
The magnetic material is separated from the magnetic pole by the increased centrifugal force
Guides the magnetic flux to the outside of the rotor inside the magnetic material enclosure
Flux guide has to so that you lost.

[0027]

Therefore, according to the brushless DC servo motor according to the first aspect, a low-speed rotation state where the load torque is large.
In, the magnetic flux is guided from the magnetic pole of the permanent magnet to the outside of the rotor
It is possible to deactivate the magnetic flux guiding means forming the magnetic flux guiding path.
No centrifugal force is generated, but the centrifugal force
Increases, the magnetic flux guide path that guides the magnetic flux to the outside of the rotor disappears.
And the magnetic flux guiding means is deactivated, forming a magnetic flux guiding path.
Leaks out of the rotor from the poles of the permanent magnet
The magnetic flux acting on each coil of the stator becomes smaller,
The rotation limitation of the rotor due to the magnetic action is reduced.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a brushless D according to the present invention will be described.
An embodiment of a C servomotor will be described in detail with reference to the accompanying drawings. In describing the embodiments of the present invention,
According to the rotation speed of the motor without using a mechanical mechanism
Technical example of brushless DC servo motor that can obtain torque
Show

FIG. 1 shows a brushless DC servomotor 1 according to a first technical example, in which a brushless DC servomotor 1 is fixed to a case.
It comprises a stator composed of a set of coils L1, L2, L3 and, for example, a cylindrical rotor unit 2. The rotor unit 2 includes a permanent magnet 2a,
b, the two magnetic poles are located at positions symmetrical to each other, the position of the magnetic pole of the permanent magnet 2a is detected by a sensor (not shown) such as a Hall element, and a coil is formed in accordance with the position of the magnetic pole of the permanent magnet 2a. When the control circuit 3 performs power supply control to the L1 to L3, an attraction force or a repulsion force is generated between the control circuit 3 and the magnetic pole of the permanent magnet 2a, and a force for rotating the rotor unit 2 in a fixed direction is applied.

The details of the rotor unit 2 will be described.
The main structure of the rotor unit 2 is a hollow cylindrical peripheral wall member 4 made of a non-magnetically permeable material, and a solid substantially cylindrical core member 5 holding a magnet 2a and having a slightly smaller diameter than the magnet 2a. And a magnetic flux made of a high-permeability material provided so as to close the gap between the magnetic pole of the magnet 2a and the inner surface of the peripheral wall member 4 in the annular space generated between the peripheral wall member 4 and the core member 5. Derivative 6
a, 6b, the magnetic flux derivatives 6a, 6b and the air gap 7
a, a rotor magnetic flux guide path forming member 6c made of a high magnetic permeability material provided so as to close an annular space formed between the peripheral wall member 4 and the core member 5 via the core members 5a, 7b, 7c and 7d; 6d.

The first movable body 8a made of a high-permeability material having a required shape capable of closing the gap 7a between the magnetic flux conductor 6a and the in-rotor magnetic flux guide path forming body 6c is formed of the core 5
The first movable body 8a is retracted by the coil spring 9a so as to be accommodated in the first movable body accommodation space 5a formed therein. When a force opposing the traction force of the coil spring 9a acts, the first movable body 8a becomes movable. The sliding movement from the inside of the accommodation space 5a to the space 7a results in a state where the gap from the magnetic flux conductor 6a to the magnetic flux guide path forming body 6c in the rotor is filled with the high magnetic permeability material.

Similarly, the second movable member 8b made of a high-permeability material having a required shape capable of closing the gap 7b between the magnetic flux conductor 6a and the magnetic flux guide path forming member 6d in the rotor is formed of the core member 5b.
So that it is retracted by the coil spring 9b so as to be housed in the second movable body housing space 5b formed therein.
The third movable body 8c made of a high-permeability material having a required shape capable of closing a gap 7c between the magnetic flux conductor 6b and the in-rotor magnetic flux guide path forming body 6c is a third movable body formed in the core body 5. The high permeability of a required shape capable of closing the gap 7d between the magnetic flux guide 6b and the rotor magnetic flux guide path forming body 6d so as to be drawn by the coil spring 9c so as to be housed in the body housing space 5c. Fourth movable body 8d made of magnetic susceptibility material
Are respectively set so as to be retracted by the coil spring 9d so as to be accommodated in the fourth movable body accommodation space 5d formed in the core body 5.

The rotor unit 2 configured as described above
In the stationary state, the first to fourth movable bodies 8a to 8d
Are drawn into the first to fourth movable body housing cavities 5a to 5d by the coil springs 9a to 9d, respectively.
The magnetic flux coming out of the N pole of the magnet 2 a
Almost no leakage to 7d, the magnetic flux guides 6a and 6b efficiently guide the inner peripheral surface of the peripheral wall body 4 to the outside from the outer peripheral surface of the rotor unit 2 to reach the S pole (FIG. 2).
(A)).

Then, the control circuit 3 sends the coils L1 to L3
When the rotor unit 2 starts rotating by the power supply control to the motor and gradually increases the rotation speed, the first to fourth movable members 8a to 8a
8d, centrifugal force starts to act against the traction force of the coil springs 9a to 9d, and the first to fourth movable members 8a to 8d.
8d moves in a direction to close the gaps 7a to 7d, and the gap between the magnetic flux conductors 6a, 6b and the rotor magnetic flux guide path forming bodies 6c, 6d is filled with a high magnetic permeability material. In the rotor unit 2, a magnetic flux conductor 6 is provided.
a → first movable body 8a → rotor magnetic flux guide path forming body 6c →
The magnetic path in the rotor from the third movable body 8c to the magnetic flux derivative 6b, and the magnetic flux in the rotor from the magnetic flux derivative 6a to the second movable body 8b → the magnetic flux guide path forming body 6d in the rotor → the fourth movable body 8d → the magnetic flux derivative 6b. And the magnetic flux leaking out of the rotor unit 2 is reduced, and the stator coils L1 to L
The magnetic flux density acting on 3 becomes low.

That is, in the first technical example described above , the magnetic paths in the rotor that short-circuit both magnetic poles of the permanent magnet 2a with a high magnetic permeability material are formed by the magnetic flux derivatives 6a and 6b and the magnetic flux guide path forming body 6c in the rotor. , 6d and first to fourth movable bodies 8a to 8d .
For example, the providing the first to fourth movable body 8a~8d to the rod 5 1
Mechanical force such as gears by applying a force (force for moving the magnetic path in the rotor toward the rotation shaft 2b) from the magnetic path in the rotor to the fourth movable body housing portions 5a to 5d by the coil springs 9a to 9d.
Obtain torque according to motor rotation without using
Can be

This characteristic will be described with reference to FIG. 3. The magnetic flux density B at the time of low-speed rotation is B ₀ and the coil springs 9 a to 9
In a low-speed range where no centrifugal force acts to move the first to fourth movable bodies 8a to 8d against the traction force of d (the range of points a to b in FIG. 3), the actuator acts on the stator. However, when the load torque decreases and the rotor unit 2 exits the low speed region, the centrifugal force exceeds the traction force of the coil springs 9a to 9d, and the air gaps 7a to 7d The first to fourth movable bodies 8a to 8
As d moves (the range from point b to point c in FIG. 3), the magnetic flux density B acting on the stator decreases to B ₀ / n.
Therefore, in the high-speed range (the range of points c to d in FIG. 3), it is possible to further increase the rotation speed.

Therefore, the rotor unit 2 having the above-described configuration
In the brushless DC servo motor 1 including the above, it is possible to obtain characteristics as shown in FIG. That is, in a state where the rotor magnetic path forming means is not functioning,
The point a is such that the torque decreases as the rotation speed increases.
From the point b to the point c such that when the magnetic path forming means in the rotor starts to function, the degree of increase in the rotational speed with the decrease in torque increases. Is completely formed, and when the magnetic flux B acting on the stator from the rotor unit 2 becomes 1 / n, the point d changes from the point c to the point d.
Presents a particular

In other words, when the magnetic flux B acting on the stator from the rotor unit 2 becomes 1 / n, the rotational speed of the rotor unit 2 becomes nV /
k _e B becomes, the more the magnetic flux induced into the rotor interior by the rotor in the magnetic path forming unit, the rotational speed is becoming higher. The characteristics of the rotation speed and the magnetic flux density can be changed by the material and shape of a member forming a magnetic path such as a movable body, the elastic coefficient of a coil spring for holding the movable body against centrifugal force, and the like. Therefore, desired characteristics can be obtained by appropriately setting these.

[0039] Thus, in the brushless DC servomotor 1 according to the first example technique, the at the time of low-speed rotation to obtain an output of high torque, at the time of low torque Ru can increase the speed.

Note that the brushless DC servo mode described above is used.
In the table 1 , the first to fourth movable bodies 8a to 8d are
Although the coil springs 9a to 9d are used to face the insides of the fourth movable body housing cavities 5a to 5d, any suitable elastic body may be used, for example, a plate-like rubber having appropriate elasticity. Etc. can be substituted. Further, the first to fourth movable bodies 8a to 8d are formed by the first to fourth movable body accommodation vacancies 5a to 5d.
The friction generated when moving from 5d to the gap portion 7a~7d becomes a sliding resistance, have good if is provided the sliding resistance reducing means that reduces the sliding resistance.

FIG. 5 shows a brushless DC servomotor 1 'according to a second technical example , in which a stator comprising three sets of coils L1, L2, L3 fixed to a case, and a cylindrical rotor unit, for example. 2 '. This rotor unit 2 'also has a permanent magnet 2a similarly to the rotor unit 2, and has an arrangement structure in which two magnetic poles are respectively located at positions symmetrical with respect to the rotation axis 2b,
The position of the magnetic pole of the permanent magnet 2a is detected by a sensor (not shown) such as a Hall element, and the control circuit 3 controls the power supply to the coils L1 to L3 according to the position of the magnetic pole of the permanent magnet 2a. This generates an attractive force or a repulsive force between the magnetic poles of the rotor unit and the magnetic poles, thereby giving a force to rotate the rotor unit 2 'in a certain direction.

The rotor unit 2 'also has a hollow cylindrical peripheral wall member 4 made of a non-magnetically permeable material, and a solid substantially cylindrical core member holding the magnet 2a and having a slightly smaller diameter than the magnet 2a. 5 in the annular space formed between the peripheral wall 4 and the core 5 and the pole tip of the magnet 2a and the peripheral wall 4
And magnetic flux derivatives 10a and 10b made of a high magnetic permeability material provided so as to close the gap between the inner wall and the inner surface, and a first magnetic body is formed in an annular space formed between the peripheral wall body 4 and the core body 5. The height is raised to a position orthogonal to the magnetic pole direction of the permanent magnet 2a so that the enclosing space 11a, the second magnetic material enclosing space 11b, the third magnetic material enclosing space 11c, and the fourth magnetic material enclosing space 11d are formed. A magnetic flux guide path forming body 10c, 10d made of a magnetic permeability material is provided in the rotor.
2 is enclosed. The magnetic fluid 12 is a colloid solution in which ferromagnetic fine particles are dispersed in a large amount in a liquid.

The rotor unit 2 'constructed as described above
In the stationary state, since the magnetic fluid 12 is attracted to the magnetic pole of the permanent magnet 2a in the first to fourth magnetic substance-filled cavities 11a to 11d, the magnetic flux emitted from the N pole of the magnet 2a is The magnetic fluxes 10a and 10b and the magnetic fluid 12 efficiently guide the inner surface of the peripheral wall 4 to the rotor unit 2 '.
Escapes from the outer peripheral surface to the S pole (FIG. 6 (a)
reference).

Then, the control circuit 3 sends the coils L1 to L3
The rotor unit 2 'starts to rotate by the power supply control to
When the rotation speed gradually increases, the magnetic fluids 12 sealed in the first to fourth magnetic body sealing cavities 11a to 11d are pressed against the inner surface side of the peripheral wall 4 by centrifugal force,
The gap between the magnetic flux guides 10a, 10b and the magnetic flux guide path forming members 10c, 10d in the rotor is filled with the magnetic fluid 12, and the magnetic flux guide 10a → the first magnetic body is enclosed in the rotor unit 2 '. The magnetic fluid 12 in the cavity 11a → the magnetic flux guide path forming body 10c in the rotor → the magnetic fluid 12 in the cavity 11c filled with magnetic material → the magnetic path in the rotor reaching the magnetic flux derivative 10b and the magnetic flux derivative 10a → the second magnetic material. The magnetic fluid 12 in the body-enclosed space 11b → the magnetic flux guide path forming body 10d in the rotor → the magnetic fluid 12 in the fourth magnetic body-enclosed space 11d
→ A magnetic path in the rotor reaching the magnetic flux derivative 10b is formed, the magnetic flux leaking out of the rotor unit 2 'is reduced, and the magnetic flux density acting on the coils L1 to L3 of the stator is reduced.

That is, in the second technical example described above , the magnetic flux derivatives 10a and 10b made of a material having a high magnetic permeability and the magnetic flux guide path forming members 10c and 10c in the rotor are provided between the magnetic poles of the permanent magnet 2a.
By dividing the magnetic fluid into four by 10d, the first to fourth magnetic substance-filled cavities 11a to 11d are formed, and the magnetic fluids 12 as fluid magnetic substances are placed in the magnetic substance-filled cavities 11a to 11d. by enclosing each magnetic enclosing hollow portion 11a~
The magnetic material adsorbed by the magnetic poles of the permanent magnets 2a in the inner wall surface of each of the magnetic material-enclosed cavities 11a to 11d by the centrifugal force that increases as the rotation speed of the rotor increases.
I spread on the inner peripheral surface) of magnetic flux 1 is a permeable wall
0a, 10b and magnetic flux guide path forming body 10c, 1 in the rotor
Rotor inner path consisting 0d and magnetic fluid being formed
Motor rotation without using mechanical mechanisms such as gears.
Ru obtained a torque corresponding to the rotation.

The brushless DC servomotor 1 'having the rotor 2' according to the second technical example can achieve the same effect as the brushless DC servomotor 1 according to the first technical example . In addition, what is enclosed in the magnetic substance enclosed space is not limited to a magnetic fluid, but a powder having magnetism,
Can Rukoto with fine metal pieces. In addition, the characteristics of the rotation speed and the magnetic flux density in the present technical example can be appropriately changed by changing the shape of the magnetic substance enclosing space, the type and the viscosity of the magnetic substance, and the like.

The first art example described above brushless DC servomotor 1 and 1 'shown in the second example technique, both actively in the rotor flux leaking to the outside of the rotor with the rotation speed increase of the rotor By forming a magnetic path in the rotor leading to
This was to reduce the magnetic flux acting on the coil.
In the present invention, the reverse approach is adopted, and when the rotor is rotating at a low speed, a magnetic flux guiding means is provided to positively guide the magnetic flux to the outside of the rotor, and the magnetic flux guiding means is deactivated as the rotating speed of the rotor increases. By doing so, the magnetic flux leaking out of the rotor is reduced. Hereinafter, embodiments of the present invention will be described.

[0048] Shown in FIG. 7 is a brushless DC servo motor 1 0 according to the embodiment of the present invention, a stator composed of three sets of coils L1, L2, L3 which is fixed to the case, for example, cylindrical rotor The rotor unit 20 includes a permanent magnet 20a. The rotor unit 20 has an arrangement structure in which two magnetic poles are respectively located at positions symmetrical with respect to the rotation axis 20b. Detected by a sensor (not shown) such as a Hall element, and the coils L1 to L
The power supply control to the third control circuit 3 0 By performed by causing a suction force or repulsive force between the magnetic poles of the permanent magnets 20a, it give a force for rotating the rotor unit 20 'to a fixed direction.

The details of the rotor unit 20 will be described. The main structure of the rotor unit 20 is a cylindrical rotating body 21 formed of a non-magnetically permeable material and holding a permanent magnet 20a therein, and the end of each magnetic pole of the permanent magnet 20a in the rotating body 21 faces. First magnetic fluid filled space 21a, second magnetic fluid filled space 21a
The magnetic fluid sealing space 21b is formed, and the magnetic fluid 22 is sealed in the first and second magnetic fluid sealing spaces 21a and 21b.

The rotor unit 20 constructed as described above
In the stationary state, since the magnetic fluid 22 is attracted to the magnetic pole of the permanent magnet 20a in the first and second magnetic substance-filled cavities 21a and 21b, the magnetic flux emitted from the N pole of the magnet 20a is Since it is efficiently guided to the outer peripheral portion of the rotating body 21 by the magnetic fluid 22, it escapes from the outer peripheral surface of the rotor unit 20 to the outside and reaches the S pole (see FIG. 8A). That is, in the present embodiment, the magnetic fluid 22 is
This serves as a magnetic flux guide path for guiding magnetic flux from both magnetic poles of the rotor 0a to the outside of the rotor.

[0051] The coil L1~L from the control circuit 3 0
When the rotation speed of the rotor unit 20 is gradually increased by controlling the power supply to the magnetic fluid 3, the magnetic fluids 22, 2 sealed in the first and second magnetic material sealed cavities 21a, 21b.
2 is separated from the magnetic pole of the permanent magnet 20a by the centrifugal force and pressed against the peripheral walls of the first and second magnetic substance-filled cavities 21a and 21b. The first and second magnetic poles at the magnetic poles of the permanent magnet 21
Since the magnetic material-filled voids 21a and 21b form a gap,
The magnetic flux reaching the outer periphery of the rotor unit 20 and leaking to the outside of the rotor decreases, and the magnetic flux density acting on the coils L1 to L3 of the stator decreases.

That is, in the embodiment of the present invention ,
By inactivating (disappearing) the magnetic flux guide path provided in advance in the rotor unit 20 by centrifugal force, the magnetic flux leaking out of the rotor during high-speed rotation is reduced. Therefore, in the present embodiment, at the time of low-speed rotation
High torque output and low torque
The number of rotations can be increased, and the transmission is separately
Heavy and bulky like the traditional motor mechanism you need
Since there is no beating, it is suitable for a drive system of a robot.
In addition, what is sealed in the magnetic material sealing space is not limited to the magnetic fluid, and magnetic powder or fine metal pieces may be used. In addition, the characteristics of the rotation speed and the magnetic flux density in the present embodiment can be appropriately changed by changing the shape and formation position of the magnetic material enclosing space, the type and viscosity of the magnetic material, and the like.

[0053]

As described above, according to the brushless DC servomotor according to the first aspect, the magnitude of the load torque is large.
In low-speed rotation, the rotor
A magnetic flux guiding means for forming a magnetic flux guiding path for guiding a magnetic flux to the outside is not required.
There is not enough centrifugal force to activate, but high-speed rotation
When the centrifugal force increases, the magnetic flux guiding means is deactivated
As a result, no magnetic flux guide path is formed,
Leaks from the poles to the outside of the rotor and acts on each coil of the stator
Magnetic flux is reduced, and the rotation of the rotor is limited by the demagnetizing action.
Reduces the maximum rotational speed of the rotor.
It becomes possible. Therefore, large torque is generated at low speed rotation.
Power is obtained and the rotation speed is increased with low torque at high speed rotation
Can provide a brushless DC servo motor
Because

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a brushless DC servomotor according to a first technical example .

FIG. 2 is an operation explanatory diagram of a rotor in a brushless DC servomotor according to a first technical example ;

FIG. 3 is a characteristic diagram of magnetic flux density and rotation speed in a brushless DC servo motor according to a first technical example .

FIG. 4 is a characteristic diagram of rotation speed and torque in a brushless DC servo motor according to a first technical example .

FIG. 5 is a schematic configuration diagram of a brushless DC servomotor according to a second technical example .

FIG. 6 is an explanatory diagram of an operation of a rotor in a brushless DC servo motor according to a second technical example .

FIG. 7 is a schematic configuration diagram of a brushless DC servo motor according to the embodiment of the present invention .

FIG. 8 is an explanatory diagram of an operation of a rotor in the brushless DC servomotor according to the embodiment of the present invention .

FIG. 9 is a schematic configuration diagram of a conventional brushless DC servomotor.

FIG. 10 is a schematic diagram showing a power supply system to a motor.

FIG. 11 is a characteristic diagram of rotation speed and torque in a conventional motor.

FIG. 12 is an explanatory diagram of an operation of a motor mechanism including a transmission that switches the output of the motor with a gear.

FIG. 13 is a characteristic diagram of rotation speed and torque in a motor mechanism having a transmission.

[Explanation of symbols]

1 0 brushless DC servo motor 20 rotor unit 2 0 a permanent magnet 2 0 b pivot shaft L1~L3 coil 21a first magnetic enclosing hollow portion 21b second magnetic enclosing hollow portion 22 magnetic

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02K 1/27 501 H02K 1/22 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A stator comprising a rotor having a permanent magnet rotatable around a rotation axis and a stator having three or more coils arranged around the rotor, and controlling power supply to each coil of the stator. By changing the magnetic field acting on both magnetic poles of the permanent magnet of the rotor, the brushless D
In the C servo motor, the magnetic poles from both poles of the permanent magnet
A magnetic flux guiding means for forming a magnetic flux guiding path for guiding the bundle;
Flux induction means increases as rotor speed increases
The magnetic flux guide path that leads the magnetic flux to the outside of the rotor due to centrifugal force disappears
A brushless DC servomotor characterized in that the brushless DC servomotor is deactivated . 2. The magnetic flux guide means according to claim 1, wherein said magnetic flux guide means is a magnetic fluid or the like.
The magnetic material-filled space containing magnetic material
And the magnetic pole of the permanent magnet faces the hollow space filled with the magnetic material.
As a result, the magnetic material attracted to the magnetic poles of the permanent magnet
From the permanent magnet pole to the outside of the rotor.
A magnetic flux guide path for guiding the bundle is formed in the magnetic material enclosed space.
And the centrifugal force that increases with the rotation speed of the rotor
The magnetic material is separated from the magnetic pole by
The magnetic flux guide path leading the magnetic flux to the outside of the rotor disappears in the air entrance
Brushless DC servo motor according to claim 1, characterized in that as that.