JPH0470866B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a linear electric machine with reduced cogging force.

(Prior art) A linear electric machine with a salient pole structure has a magnetically non-uniform structure due to the formation of winding grooves, so there is no interaction between the armature and the field part made of permanent magnets. There is a problem in that this action generates a cogging force, impairing the smooth straight movement of the mover.

Conventionally, therefore, the magnetizing waveform of the field was made into a special waveform, such as a trapezoidal waveform, and a protrusion or dummy slot for reducing cogging was provided at a portion of the armature salient pole facing the field.

FIG. 9 shows an example of the above-mentioned conventional linear electric machine, in which reference numeral 1 denotes a field consisting of a flat permanent magnet magnetized into multiple poles, 2a denotes a salient pole of an armature, and 2c
is a groove for winding between the salient poles. A protrusion 2b is provided at a portion of each salient pole 2a of the armature that faces the field 1 so as to protrude toward the field 1 and parallel to the winding groove 2c. The resulting cogging force is offset by the cogging force generated by each protrusion 2b.

FIG. 10 shows another example of a conventional linear electric machine, where 5 is a field, 6a is a salient pole of an armature,
6c is a groove for winding between the salient poles. Each salient pole 6
A plurality of dummy slots 6b are formed in a direction parallel to the winding groove 6c at a portion facing the field 1, so as to offset the cogging force generated by the winding groove 6c.

(Problems to be Solved by the Invention) In conventional linear electric machines in which the field magnetization waveform has a special shape, it is difficult to manage the magnetization to obtain a predetermined magnetization waveform, and cogging increases. Since permanent magnets cannot be used in a saturated state, there is a problem that the effective magnetic flux decreases as a whole.

In conventional linear electric machines in which a protrusion or dummy slot is provided on the salient pole of the armature, the protrusion or dummy slot provided on the salient pole must be of sufficient height or depth to offset the cogging force due to the winding groove. be. As a result, the gap between the salient poles and the field becomes larger as a whole, resulting in a decrease in effective magnetic flux, resulting in a decrease in efficiency. In addition, since the entire salient pole must be moved closer to the armature body by the amount of the protrusion or dummy slot, the winding space becomes smaller, and the winding jig becomes complicated in shape to form the protrusion. There is.

The present invention was made to solve these conventional problems, and it is possible to prevent a decrease in effective magnetic flux and a decrease in efficiency without making any special modifications to the magnetization waveform or the shape of the armature or salient poles. It is an object of the present invention to provide a linear electric machine that can reduce cogging force and prevent the winding space from becoming smaller.

(Means for Solving the Problems) The present invention provides a core parallel to the armature on at least one side of the left and right sides of the armature when viewed from the straight-travel direction, and a salient pole of the core is arranged so as to face the field. It is provided at a location that is shifted in the linear direction from the position of each groove for the winding by the field magnetic pole pitch or an integral multiple thereof, and the dimension in the linear direction of the salient pole of the attached core and the above It is characterized in that the dimensions of the groove in the straight direction are approximately equal to each other.

(Function) The cogging force generated in the winding groove part and the salient pole of the attached core installed at a location shifted by the field magnetic pole pitch or an integral multiple of this with respect to the position of the winding groove. The cogging forces are opposite to each other, and the two cogging forces cancel each other out.

Before describing embodiments of the present invention, the principle of cogging generation and the principle of reducing cogging by providing protrusions will be explained.

Generally, when a magnet approaches a ferromagnetic material such as iron, an attractive force is generated. A similar attractive force occurs in a rotating electric machine having an armature with an iron core and a magnet. If an imbalance occurs in the sum of the rotational direction components of this suction force, rotational force is generated. This is cogging torque.

As shown in Fig. 11, when the iron piece 8 is placed inside the magnetized ring-shaped magnet 7 and moved in the circumferential direction while maintaining a constant distance from the magnet 7, the N of the magnet 7 as shown in Fig. 12. Iron piece 8 is 1 regardless of pole or south pole.
One period of cogging torque is generated every time the magnetic pole is moved by one magnetic pole pitch. That is, if the number of magnetic poles is m, cogging torque of m periods is generated in one rotation.

As shown in FIG. 13, when a core 9 with a circular cross section and no grooves is placed inside the magnet 1 and rotated while maintaining a constant distance from the magnet 7, the distance from the magnet 7 increases over the entire circumference of the core 9. Since the suction force is always constant and balanced, no cogging torque occurs as shown in FIG.

Next, as shown in FIG. 15, consider the case of a core 9 in which a groove 9a is formed by removing a portion of the outer periphery of a circular core. If this core 9 is placed inside the magnet 7 and rotated while maintaining a constant distance from the magnet 7,
This core 9 has the same phase and magnitude as the cogging torque generated in the iron piece 8 shown in Fig. 11 (see Fig. 12), but only in the opposite direction (if one acts clockwise, the other acts counterclockwise). A cogging torque (acting on) is generated (see Fig. 16). That is,
A cogging torque is generated by subtracting the cogging torque of the iron piece 8 shown in FIG. 12 from the cogging torque of the core 9 shown in FIG. 14. vice versa,
If an iron piece having the same shape as the groove 9a is provided in the groove 9a of the core 9, the cogging torque generated by the groove 9a is canceled by the cogging torque generated by the iron piece. As described above, when cogging torques having the same phase and magnitude and opposite directions are applied to the cogging torque generated by the groove 9a of the core 9, the cogging torques in opposite directions cancel each other out, resulting in a cogging torque. It turns out that it is possible to eliminate

In order to cancel the cogging torque generated by the groove 9a of the core 9, if an iron piece having the same shape as the groove 9a is provided, it does not need to be inside the groove 9a of the core 9. As shown in FIG. 17, a similar effect can be obtained by providing an adjacent core 9b that matches the groove 9a on the side of the armature core 9 so as to move together with the core 9. Of course, it is necessary that the armature core 9 does not protrude from the width of the magnet 7.

As mentioned above, the cogging torque generated by the groove 9a of the core 9 has a period of one magnetic pole pitch, so as shown in FIG. Core 9 attached to the same university
By providing the groove c, the phase of the cogging torque generated by the groove 9a and the phase of the cogging torque generated by the attached core 9c can be aligned, and the two cogging torques can cancel each other out. Further, the groove 9a is not limited to the position one magnetic pole pitch away from the groove 9a, but even if an attached core having the same shape and the same size as the groove 9a is provided at any one position separated from the groove 9a by an integral multiple of the magnetic pole pitch, the groove 9a The phase of the cogging torque generated by the projection and the phase of the cogging torque generated by the protrusion can be aligned, and the same effect can be obtained.

In the examples shown in FIGS. 17 and 18, the shape and size of the attached core are the same as the shape and size of the groove, and the attached core is provided in only one place.
It is not limited to this form. 19th
As shown in the figure, cores 9d and 9e, which are half the size of the groove 9a, are placed at two locations in the above-mentioned positions, that is, in the groove 9a.
Even if it is provided at a position one magnetic pole pitch away from the groove 9a, the cogging torque generated by the groove 9a of the core 9 and the cogging torque generated by the adjacent cores 9d and 9e can cancel each other out. In other words, the cogging torque generated by the plurality of cores is adjusted such that the total amount of cogging torque generated by the plurality of cores is equal to the magnitude of the coggin torque generated by the groove, and the cogging torque generated by the plurality of cores is The phase of the cogging torque generated by the groove may be the same as the phase of the cogging torque generated by the groove. Furthermore, the same holds true no matter how many grooves there are in the core. Note that FIG. 20 shows one groove 9a.
FIG. 21 is an example of calculation of cogging torque of a core 9 having one groove 9a and one core 9.
It is an example of cogging torque calculation of the core 9 which has c. As is clear from Figures 20 and 21, 1
In the case of the core 9 having two grooves 9a and one combined core 9c, the cogging torques of the grooves 9a and the combined core 9c cancel each other out.

The above description has been about a rotating electric machine, but if the armature and magnet are developed in a straight line, the same can be said about a linear electric machine.

(Example) Hereinafter, an example of a linear electric machine according to the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 11 denotes a field consisting of a flat permanent magnet magnetized into multiple poles in the longitudinal direction;
is the armature. Either the field 11 or the armature 12 can move straight relative to the other in a direction perpendicular to the plane of the paper in FIG. Adjacent cores 13, 1 are provided on both left and right sides of the armature 12 when viewed from the straight-ahead direction.
3 is provided. Armature 12 and attached core 13
is arranged facing the field 11. Since the annexed core 13 is provided for the purpose of reducing cogging torque, it is not necessary to have a coil wound thereon, or a coil may be wound thereon if necessary. The attached core 13 moves integrally with the armature 12 relative to the field 11.

The attached core 13 in the example of FIG. 1 is formed in the shape of a square prism and is arranged on both sides of the armature 12, but the attached core 14 in the example of FIG. 2 has a hook-shaped portion facing the field 11. The armature 12 is bent to increase the area facing the field 11, and the core 14 is disposed only on one side of the armature 12 when viewed from the straight direction.

3-5 illustrate the embodiment of FIG. 1 in more detail. In FIGS. 3 to 5, the field 11
In the armature 12, three salient poles 12a, 12b, 12c and grooves 21a, 21b, 21c for winding between these salient poles are arranged to face each other in the two magnetic pole ranges. On the other hand, the attached core 13 has salient poles 13a, 13b, 13c, . . . facing the field 11, and these salient poles have grooves 21a, 21b, 21c for each winding.
The magnetic pole pitch of the field 11 in the straight direction based on the position of
It is provided at a location shifted by P _P and at a location shifted by twice the magnetic pole pitch P _P. To be more specific, salient poles 13a of the core provided on both sides of the salient pole 12a of the armature are provided, salient poles 13b of the provided core are provided on both sides of the groove 21a for the winding, and the salient poles 13b of the provided core are provided on both sides of the salient pole 12a of the armature. Salient poles 13c, 13d, 13e, and 13f of the adjacent core are arranged on both sides of the winding groove 21b, on both sides of the salient pole 12c, and on both sides of the winding groove 21c, respectively. The salient poles of the attached core arranged with the position of the winding groove 21a as a reference are 13e, 13b, and the salient poles of the attached core arranged with the position of the winding groove 21b as a reference are 13d, 13a, and the winding groove 21c. The salient poles of the adjacent cores arranged as references are 13f and 13c. The linear dimension of each salient pole of the attached core is 11,
If the linear dimension of the groove for each winding is 12, it is 11.
12 are almost equal.

As shown in FIG. 5, it is assumed that the armature and the attached core move straight relative to the right side with respect to the field 11. Now, as shown in FIG. 5, the salient pole 12a of the armature is about to move away from one neutral point A of the field 11, and the attached core is moving away from the neutral points B and C of the field 11. Assuming that the salient poles 13c and 13f are about to enter, a cogging force is generated at the neutral point A and the neutral points B and C. The cogging force generated at neutral point A and the cogging force generated at neutral points B and C are in opposite directions, and the cogging forces cancel out as a whole. That is, the center of the magnetic pole between neutral points A and B tries to pull in the salient pole 12a, and a force acts to move the armature in the same direction as the moving direction indicated by the arrow, and the center of the magnetic pole between neutral points A and B The center of the magnetic pole between them is trying to pull in the salient pole 13c of the attached core, and the center of the magnetic pole between neutral points B and C is trying to pull in the salient pole 13f of the attached core, and the armature is moving in the opposite direction to the direction indicated by the arrow. A force acts to move it in the direction. These opposing forces are approximately equal as described with respect to FIGS. 11-21, and the cogging forces will cancel out as a whole. Conversely, when one salient pole of the armature tries to enter one neutral point, the two salient poles of the attached core try to move away from the two neutral points, and one salient pole of the armature The cogging force generated by the two salient poles of the adjacent core is canceled out, and the cogging force is canceled out as a whole.

According to the above embodiment, it is not necessary to make the magnetization waveform of the field into a special shape, and it is sufficient to achieve saturation magnetization as a whole, so that the magnetization can be easily managed and sufficient magnetic flux can be obtained. Further, since there is no need to provide a protrusion on the surface of each salient pole of the armature facing the field, and there is no need to provide a dummy slot, each salient pole as a whole does not retreat toward the armature main body. Therefore, it is possible to prevent a decrease in effective magnetic flux, the winding space is not limited, and it is possible to reduce cogging force while preventing a decrease in efficiency.

Generally speaking, the salient poles of the attached core may be arranged at positions that are shifted in the straight direction from the position of each groove for the winding by the field magnetic pole pitch or an integral multiple of this, and one winding. The number of salient poles of the core attached to the wire groove may be one or more.

FIG. 6 shows an embodiment in which four salient poles of adjacent cores are provided for one winding groove. In Fig. 6, the armature 3
Salient poles 12a, 12b, 12c are arranged, and winding grooves 21a, 21b, 21 are arranged between these salient poles.
There is c. Within the range of four magnetic poles of the magnetic pole pitch P _P of the field 15, there are salient poles 14a, 14 of the attached core.
There are 4 each of b and 14c, 12 in total. The four salient poles 14a of the attached core arranged within the range of the above four magnetic poles have grooves 2 for winding.
It is provided at a position shifted from the position of 1a by the magnetic pole pitch P _P and an integral multiple thereof. Similarly, the four salient poles 14b of the attached core arranged within the range of the four magnetic poles are salient poles arranged with the groove 21b as a reference, and are arranged within the range of the four magnetic poles. The four salient poles 14a of the attached core are in the groove 2.
These are salient poles arranged with reference to 1c. In the case of this embodiment as well, the dimensions in the straight direction of each salient pole of the attached core and the dimensions in the straight direction of each winding groove are approximately equal.

In the above embodiment, the number of salient poles of the core attached to one winding groove is 4, which is twice that of the previous embodiment, and the cogging force generated by one winding groove is Since the cogging force generated by the four salient poles of the attached core is used to cancel out the cogging force, the attached core is disposed only on one side of the left and right sides of the armature when viewed from the straight direction.

The seventh example is an embodiment in which a commutating pole is provided in the winding groove between each salient pole of the armature. In Fig. 7, three salient poles 1 of the armature are placed in the two magnetic pole ranges of the field 17.
6a, 16b, 16c are arranged facing the field 17, and between these salient poles there are grooves 22a, 22b, 22c for winding. The commutating electrode 18a,
18b and 18c are arranged. Either the field 17 or the armature can move straight in the horizontal direction in the figure relative to the other, and the salient poles 19a, 19b of the attached core are on the left and right when viewed from the straight direction, that is, on both sides in the vertical direction in the figure. , 19c are provided. The above-mentioned salient poles of the attached core are provided one by one for each winding groove, and a salient pole is provided in each winding groove at a position shifted by the magnetic pole pitch P _P of the field 17 in the straight direction with respect to the position. It is located. Specifically, the salient pole corresponding to the groove 22a is 19c, the salient pole corresponding to the groove 22b is 19a, and the salient pole corresponding to the groove 22c is 1.
It is 9b. Since the cogging force generated by one winding groove and the cogging force generated by the commutating pole in the groove are opposite to each other, one salient pole of the adjacent core is a cogging pole at the center in the straight direction. It is divided into two by grooves 23a, 23b, and 23c whose dimensions correspond to the dimensions in the straight direction of the wire, so that both the cogging force generated in the winding groove portion and the cogging force generated in the interpolation portion can be canceled out. . Each groove 23a, 23b, 23
Each salient pole 19a, 19 of the attached core divided by c
The dimension 11 in the straight direction of each divided piece b, 19c is:
Each winding groove 22a, 22b divided by each commutating pole,
It is approximately equal to the dimension of each divided portion of 22c in the straight direction. In this embodiment, since the number of salient poles of the annexed core is relatively small, the dimension of each salient pole of the annexed core in the direction orthogonal to the rectilinear direction is formed to be relatively long. The above-mentioned embodiment of this embodiment also provides the same cogging reduction effect and other effects as the embodiment.

The embodiment of FIG. 8 also has each salient pole 16a, 16 of the armature.
Winding grooves 22a, 22b, 22 between b and 16c
This is an example in which commutating poles 18a, 18b, and 18c are provided in c. In this example, the salient poles of the attached core are placed only on one side of the armature when viewed from the straight direction, and
The salient poles of the annexed core are provided at positions shifted by the magnetic pole pitch P _P of the field 17 and twice the pitch with respect to the position of the groove for each winding. That is, two salient poles 20a, 20a of the attached core are arranged corresponding to the groove 22a for winding, and salient poles 20b, 20b of the attached core are arranged corresponding to the groove 22b for winding. Groove 2
Two salient poles 20c, 2 of the attached core correspond to 2c.
0c is placed. In this example as well, each salient pole of the adjacent core is divided into two by a groove corresponding to each commutative pole. The linear dimension 11 of each divided piece of each of the bisected salient poles of the annexed core is approximately equal to the linear dimension 12 of each divided portion of each winding groove bisected by each commutating pole. This embodiment also provides the same effects as the embodiment shown in FIG.

The pitch of the arrangement position of the salient poles of the attached core to reduce the cogging force must be in the same phase as the winding groove. Here, if the field magnetic pole pitch is P _P and the armature winding groove pitch is M _P , then the greatest common divisor of P _P and M _P , Q _P, is the arrangement position pitch of the salient poles of the attached core. By doing so, the cogging force can be reduced.
In this case, the number of salient poles of the core attached to one winding groove is M _P /Q _P. If M _P /Q _P is 2 or more, there is a large cogging reduction effect even if the attached core is thin. Also, like the salient pole 14 in the example of FIG. 2, if the salient pole of the attached core is bent into a hook shape and made to face the field, the area facing the field can be increased. The attached core can be made even thinner.

(Effect of the invention) According to the invention, a core is provided on the armature side,
The cogging force was reduced by providing the salient poles of this annexed core at locations shifted from the field magnetic pole pitch or an integral multiple thereof with respect to the winding, etc.
There is no need to make the field magnetization waveform into a special shape,
Since there is no need to provide a protrusion or dummy slot toward the field on the surface of the armature facing the field, it is possible to reduce the cogging force while preventing a decrease in effective magnetic flux and efficiency. Furthermore, since the winding space can be increased, winding can be easily done and the magnetic force of the armature can be increased. Since the surface of the armature facing the field can be formed flat without any protrusions, the shape of the winding jig can be simplified.

[Brief explanation of the drawing]

1 is a side view showing one embodiment of the linear electric machine according to the present invention, FIG. 2 is a side view showing another embodiment of the linear electric machine according to the present invention, and FIG. 3 is a side view of the embodiment of the linear electric machine according to the present invention. FIG. 4 is a perspective view showing a portion of the field; FIG. 4 is a front view of the field and a plane of the armature portion in the same embodiment, showing the relationship between the two; FIG. 5 is a front view showing the relationship between the field and the armature portion. , FIG. 6 is a diagram showing another embodiment of the present invention in the front view of the field and the plane of the armature portion, and FIG. 7 is a diagram showing still another embodiment of the present invention in the front view of the field and the plane of the armature portion. , FIG. 8 is a diagram showing still another embodiment of the present invention in the front view of the field and the plane of the armature portion, FIG. 9 is a front view showing an example of a conventional linear electric machine, and FIG. FIG. 11 is a front view showing another example of a conventional linear electric machine, FIG. 11 is a plan view showing a state in which an iron piece is placed in a magnet, FIG. 12 is a waveform diagram showing cogging torque generated in the same iron piece, and FIG. 13 is a plan view showing a state in which a core with a circular cross section is placed in a magnet;
Figure 4 is a waveform diagram showing the cogging torque generated in the same core, Figure 15 is a plan view showing a core with a circular cross section and grooves placed in a magnet, and Figure 16 is the cogging torque generated in the same core. FIG. 17 is a developed diagram showing the relationship between a grooved core and a magnet, FIG. 18 is a developed diagram showing the relationship between a core with a groove and an attached core and a magnet, and FIG. FIG. 20 is a developed diagram showing the relationship between a core with an attached core and a magnet; FIG. 20 is a waveform diagram showing the relationship between an armature core with grooves, magnetic flux, and cogging torque;
FIG. 1 is a waveform diagram showing the relationship between an armature core having a groove and an attached core, magnetic flux, and cogging torque. 11, 15, 17...field magnet, 12a, 12b,
12c, 16a, 16b, 16c...Salient poles of armature, 21a, 21b, 21c, 22a, 22b,
22c...Groove for armature winding, 13a, 13
b, 13c, 14a, 14b, 14c, 19a,
19b, 19c, 20a, 20b, 20c... Salient poles of the attached core.

Claims (1)

[Claims] 1.Equipped with a multi-pole magnetized field and an armature having salient poles and winding grooves arranged opposite to this field, and either one of the field and the armature In a linear electric machine that moves the armature in a straight line relative to the other, a core is provided parallel to the armature on at least one side of the left and right sides of the armature when viewed from the straight direction,
The salient pole of this annexed core is provided at a portion facing the field and shifted in the straight direction from the position of each groove for the winding by the magnetic pole pitch of the field or an integral multiple thereof, A linear electric machine characterized in that the dimension of the salient pole of the annexed core in the linear direction and the dimension of the groove in the linear direction are approximately equal.