JPH0441753Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a variable gap type motor suitable for use, for example, in driving the arm of an industrial robot.
In particular, the present invention relates to a variable gap type motor that reduces vibration and noise and improves power efficiency.

[Prior Art] Conventionally, variable gap type motors as shown in FIGS. 3A to 3D have been known as motors whose operating principle is completely different from that of general motors. In these figures, 1 is a stator, which includes a cylindrical core 1a with eight pole teeth (not shown) formed on its inner periphery, and a coil (not shown) wound around each pole tooth. It consists of As a result, eight magnetic poles a to h are provided along the inner peripheral surface of the stator 1, as shown in FIG. 3C. By sequentially supplying an excitation current to each coil of the stator 1, the magnetic poles a to h are sequentially excited. The stator 1 is housed in a frame 2 as shown in FIG. bearing 4,
4, each is rotatably supported. One end of a crank plate 5, 5 is fixed to each inner end of the two output shafts 3, 3, and a support shaft 7 of a rotor 6 is fixed to the other end of each crank plate 5, 5. Both ends are fixed. In this case, the distance l between each axis of the output shaft 3 and the support shaft 7 (Fig. 3 A) is slightly smaller than the length obtained by subtracting the radius R of the rotor 6 from the radius n of the inner circumference of the core 1a. There is. Further, the rotor 6 is made of a cylindrical magnetic material,
As shown in FIG. 3B, it is rotatably supported by a support shaft 7 via bearings 8, 8.

With the above configuration, the rotor 6 is able to rotate around the support shaft 7 while revolving around the axis of the output shaft 3, as shown in FIG. 3C. As a result,
The rotor 6 can revolve with a part of its outer periphery always being close to the inner periphery of the stator 1. For example, when the rotor 6 is positioned as shown in FIG. 3C, when the magnetic pole b is excited, a magnetic attraction force is generated between the magnetic pole b and the rotor 6. As a result, the rotor 6 is attracted in the direction of narrowing the gap G with the magnetic pole b, that is, in the direction of the arrow F. As a result, the rotor 6 starts to revolve around the axis of the output shaft 3 in the direction of arrow _A1 , and along with this revolution, starts to rotate around the support shaft 7 in the direction of arrow B. Thereafter, when the magnetic poles c, d, and e are sequentially excited, the rotor 6 is attracted to the magnetic poles c, d, e, etc. one after another, and the rotor 6 moves in the direction indicated by the arrow A.
It continues to revolve continuously in the direction, and this revolution movement is outputted to the outside by the output shaft 3.

The variable air gap type motor described above has magnetic poles a, b, c...
It has a structure in which the air gap between ... and the rotor 6 changes, and a magnetic attraction force (variable air gap force) is applied directly to the rotor 6 to cause the rotor 6 to revolve, and this revolving force produces a rotational output. I am getting . On the other hand, the gap between the rotor and stator is always constant. A general motor, a so-called fixed air gap type motor, does not utilize the above-mentioned magnetic attraction force, but only uses a tangential force (fixed air gap force) orthogonal to the field magnetic flux generated from the magnetic poles. Here, it is generally known that the variable pore force is extremely large compared to the fixed pore force.
As a result, variable gap type motors can obtain larger torque than fixed gap type motors, and therefore can be used as drive sources that require high torque, such as arm drives of industrial robots. Conceivable.

[Problems to be solved by the invention] By the way, in the conventional variable gap type motor described above, the center of gravity of the rotor 6 is located on the support shaft 7 which is separated by a distance l from the axis of the output shaft 3. is an eccentric rotation, that is, an eccentric load rotation. As a result, as the rotor 6 revolves,
There was a problem in that vibrations occurred throughout the rotating system, and noise was generated along with this vibration.

Further, in the conventional variable gap type motor described above, the rotor 6 is formed in a cylindrical shape as shown in FIG. A space S is formed between the inner circumferential surface of the support shaft 7 and the outer circumferential surface of the support shaft 7, which substantially corresponds to the difference between the outer circumference and the inner circumference of the bearings 8, 8. For this reason,
When the rotor 6 revolves, the magnetic flux flowing into the rotor 6 from the magnetic poles flows through the bearings 8, which have lower magnetic resistance than the space S.
8 and is guided to the support shaft 7, however,
These bearings 8, 8 are used for the rotor 6 in terms of material and structure.
Magnetic resistance is large compared to As a result, sufficient magnetic attraction force cannot be obtained unless the excitation current is increased.
Therefore, power efficiency becomes low. For this reason, the present inventor considered a variable gap type motor having a structure in which an annular convex portion 6a is provided on the inner circumferential surface of the rotor 6 and brought close to the support shaft 7, as shown in FIG. Then, the magnetic flux φ flowing into the rotor 6 from the magnetic poles flows into the convex portion 6
a and is guided to the support shaft 7. As a result, the density of the magnetic flux φ increases in the convex portion 6a, and the magnetic resistance increases. Therefore, similar to the above, this causes a decrease in power efficiency.

This invention was made in view of the above circumstances, and its purpose is to provide a variable air gap motor that reduces vibration and noise and further improves power efficiency.

[Means for Solving the Problems] This invention consists of a cylindrical stator that generates a rotating magnetic field along its inner circumferential surface, and a stator that is disposed penetratingly on the central axis of the stator and is rotatable. a supported output shaft, and arranged parallel to the output shaft and at equal intervals on a virtual circumference centered on the output shaft,
a plurality of substantially cylindrical rotors that revolve in close proximity to the inner circumferential surface of the stator; support shafts that rotatably support each of the rotors via bearings; and each of the support shafts and a revolution plate that is attached to the shaft and transmits the revolution of each of the rotors to the output shaft, the axial length of the rotor being longer than the axial length of the stator. The gap between the rotor and the support shafts is reduced on either or both of the inner peripheral surface of the rotor or the outer peripheral surface of each of the support shafts. The present invention is characterized in that an annular convex portion is formed, and the length of the convex portion in the axial direction is the same as that of the stator.

[Operation] According to this invention, since the plurality of rotors are arranged parallel to the output shaft and at equal intervals on the virtual circumference centered on the output shaft, the center of gravity of the entire rotating system and The axis line of the output shaft matches. Therefore,
Vibration accompanying the revolution of each rotor and noise accompanying this vibration are reduced.

In addition, the axial length of the convex portion, that is, the path of the magnetic flux guided from the rotor to the support shaft, is equal to the axial length of the stator, and the convex portion allows the path between the rotor and the support shaft to Since the gap is small, the magnetic flux flowing from the stator to the rotor due to the rotating magnetic field passes through the rotor with uniform density and is guided from the rotor to the support shaft through a small gap. Therefore, magnetic resistance becomes small.

[Example] Hereinafter, an example of this invention will be described with reference to the drawings. In FIGS. 1A, 1B, and 1C, 20 is a stator, which includes a cylindrical core 20a on the inner periphery of which 12 pole teeth (not shown) are formed at equal intervals, and a stator for each pole tooth. It is composed of a wound coil (not shown). As a result, magnetic poles a ₁ to _{a 4} , b ₁ to b ₄ , c ₁ to
c ₄ is provided. An output shaft 21 is disposed to pass through the center axis C of the stator 1, and the output shaft 21 is rotatably supported by a frame (not shown) via a bearing (not shown). Also,
This output shaft 21 has a revolution plate 2 formed in a cross shape.
The central parts of 2 and 22 are each fixed. Both ends of support shafts 23a to 23d, which are arranged parallel to the output shaft 21, are fixed to the revolution plates 22, 22 at positions spaced apart from the center by a distance m in all directions. Rotors 25a to 25d are rotatably supported on these support shafts 23a to 23d via bearings 24a to 24d, respectively. These rotors 2
5a to 25d are each made of a substantially cylindrical magnetic body, and their total length _L2 is longer than the axial length L of the stator 1 as shown in FIG.
23a is formed to be long on both sides by an amount corresponding to the length _L1 , and on the inner peripheral surface thereof, the axial length is the same length L as the stator 1, and each support shaft 23a to 23
The annular protrusions 30 are each formed such that the gap between the protrusions 30 and the outer peripheral surface of the protrusions d is about 1/100 mm. Furthermore, the radius r of the rotors 25a to 25d is determined by subtracting the distance m between the axes of the output shaft 21 and the support shafts 23a to 23d from the radius n of the inner circumference of the stator 20, as shown in FIG. It is slightly smaller than Sayaka. With such a configuration, the rotors 25a to 25d are
The rotors 25a and 25c are arranged at equal intervals (90 degrees as a center angle) on a virtual circumference centered on the output shaft 21, and the rotors 25a and 25c are symmetrical with respect to the output shaft 21. The children 25d are located symmetrically. And these rotors 25a to 25d
While revolving around the axis of the output shaft 26 with a part of the outer circumference always being close to the inner circumferential surface of the stator 20,
Each of them is rotatable around support shafts 23a to 23d.

In the above configuration, for example, the rotors 25a to
25d is _{positioned as shown} in _{FIG .}
Between magnetic pole a ₂ and rotor 25b, between magnetic pole a ₃ and rotor 2
5c, a magnetic attraction force is generated between the magnetic pole _a4 and the rotor 25d, and the rotors 25a to 25d
is the direction in which the gap between the magnetic poles _a1 to _a4 is narrowed, that is, the rotor 25a is moved in the direction of the arrow Fa,
The rotor 25b is attracted in the direction of arrow Fb, the rotor 25c is attracted in the direction of arrow Fc, and the rotor 25d is attracted in the direction of arrow Fd. As a result, the rotors 25a to 2
5d begins to revolve in the direction of arrow _Q1 around the axis of the output shaft 26, and along with this revolution, the rotor 25a
~25d is an arrow P centered around the support shafts 23a~23d
Start rotating in the direction. From then on, magnetic poles b ₁ to b ₄ , then magnetic poles c ₁ to _{c 4} , and again magnetic poles a ₁ to a ₄ , each with a central angle
By sequentially exciting the magnetic poles shifted by 90 degrees, the rotors 25a to 25d are attracted to the magnetic poles b ₁ to b ₄ , then to the magnetic poles c ₁ to c ₄ , and again to the magnetic poles a ₁ to _{a 4} in the same manner as above. . As a result, the rotors 25a to 25d continue to revolve in the direction of the arrow Q in the same manner as described above, and this revolving force is applied to the output shaft 21 via the support mechanism consisting of the bearings 24a to 24d, the support shafts 23a to 23d, and the revolution plate 22. As a result, the output shaft 21 rotates.

According to the above configuration, each rotor 25
The total length L ₂ of bearings 23 a to 25 d is longer than the axial length L of rotor 1 by a length L ₁ corresponding to the length L ₁ of bearings 23 a to 23 d on both sides, and a support shaft is attached to the inner circumferential surface of the bearings 23 a to 23 d. Since an annular convex portion 30 having a gap of 1/100 mm from 24a to 24d is provided, and the convex portion 30 is formed to have the same length as the axial length L of the stator 1, for example, from the magnetic pole a ₁ to the rotor 25a. As shown in FIG. 2, the inflowing magnetic flux φ passes straight through the convex portion 30 of the rotor 25a with uniform density and is guided to the support shaft 23a through a gap of 1/100 mm. Similarly,
The magnetic flux φ flowing from each magnetic pole a ₂ to _{a 4} to each rotor 25b to 25d also flows into the convex portion 30 of each rotor 25b to 25d.
It passes through with a uniform density and is guided to the support shafts 23b to 23d through a gap of 1/100 mm. This results in
Unlike conventional variable gap type motors, the rotor 25a~ does not pass through bearings and has a uniform magnetic flux density.
Since the magnetic flux passes through each of the sections 25d, the magnetic resistance becomes smaller compared to the conventional case. As a result, sufficient magnetic attraction force can be obtained even if the excitation current of the coil is small, and therefore power efficiency is improved compared to the conventional method. Also,
Since the rotors 25a to 25d are arranged parallel to the output shaft 21 and at equal intervals on a virtual circumference centered on the output shaft 21, the center of gravity of the entire rotating system coincides with the axis of the output shaft, and vibrations are reduced. And the noise associated with this vibration is completely prevented. In addition, since the structure is such that one output shaft 21 passes through the center axis of the stator 20, the axes of the two output shafts 3, 3 (see Fig. 3 A) are aligned, as in the conventional case. It is not necessary and manufacturing is easy.

Note that in the above embodiment, the rotor 25a
Although an annular convex portion 30 was provided on the inner peripheral surface of ~25d,
An annular projection is provided on the outer peripheral surface of the support shafts 24a to 24d, or an annular projection is provided to both the rotors 25a to 25d and the support shafts 24a to 24d, so that the rotors 25a to 25d and the support shafts 24a to 24d It is also possible to have a structure in which the two are placed close to each other. In addition, in the above-mentioned embodiment, a case was explained in which a coil is wound around each pole tooth of the stator 20 to form a magnetic pole. A plurality of slots are formed in the core 20a, coils are continuously wound around these slots, and an alternating current is passed through the coil to continuously generate a rotating magnetic field along the inner circumferential surface of the core 20a. It may be configured so that it is magnetically attracted.

[Effects of the invention] As explained above, according to this invention, a plurality of rotors are arranged parallel to the output shaft and at equal intervals on a virtual circumference centered on the output shaft. Therefore, the center of gravity of the entire rotating system and the axis of the output shaft coincide. Therefore, the vibration accompanying the revolution of each rotor and the noise accompanying this vibration can be reduced.

In addition, the axial length of the convex portion, that is, the path of the magnetic flux guided from the rotor to the support shaft, is equal to the axial length of the stator, and the convex portion allows the path between the rotor and the support shaft to Since the gap is small, the magnetic flux flowing from the stator to the rotor due to the rotating magnetic field passes through the rotor with uniform density and is guided from the rotor to the support shaft through a small gap. As a result, the magnetic resistance becomes small, so even if the excitation current is made small, a sufficient magnetic attraction force can be obtained, and power efficiency can be improved.

[Brief explanation of the drawing]

Figures 1A, 2B, and 3 are exploded perspective views, partial sectional views, and front views showing the configuration of an embodiment of this invention, and Figure 2 shows rotors 25a, 25b, and 25b of the same embodiment.
25d is a magnetic flux line diagram, FIG. 3 is an exploded perspective view, partial sectional view, front view, and side sectional view showing the configuration of a conventional variable gap type motor, and FIG. 4 is a diagram showing problems. It is a magnetic flux line diagram for explanation. 20... Stator, 21... Output shaft, 22, 22
...Revolution plate, 23a to 23d...Support shaft, 24a
~24d...bearing, 25a~25d...rotor,
30...Protrusion.

Claims (1)

[Claims for Utility Model Registration] A cylindrical stator that generates a rotating magnetic field along its inner peripheral surface, an output shaft that is disposed penetrating the central axis of the stator and is rotatably supported. , a plurality of substantially cylindrical tubes arranged parallel to the output shaft and at equal intervals on a virtual circumference centered on the output shaft, and revolving in close proximity to the inner circumferential surface of the stator; A rotor, a support shaft that rotatably supports each of the rotors via a bearing, and a revolution plate to which each of the support shafts is attached and which transmits the revolution of each of the rotors to the output shaft. A variable gap type motor, wherein the axial length of the rotor is longer than the axial length of the stator by an amount corresponding to the length of the bearing, and the inner circumferential surface of the rotor or each of the An annular convex portion is formed on one or both of the outer circumferential surfaces of the support shaft so that the gap between the rotor and the support shaft is small, and the length of the convex portion in the axial direction is A variable gap type motor characterized by being formed to have the same length as the stator.