JPH0530143B2 - - 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) In a linear electric machine with a salient pole structure, the armature core has a magnetically non-uniform structure due to the formation of winding grooves. There is a problem in that a cogging force is generated due to the interaction with the movable element, and smooth straight movement of the movable element is impaired.

Therefore, conventionally, a protrusion or dummy slot for reducing cogging has been provided at a portion of the salient pole of the armature that faces the field.

FIG. 7 shows an example of the above-mentioned conventional linear electric machine, in which reference numeral 1 indicates a field consisting of a flat permanent magnet magnetized into multiple poles, and 2 indicates an armature, which is the ultimate 2a.
A groove 2C for winding is provided between these salient poles 2a. A protrusion 2b is provided at a portion of each salient pole 2a of the armature 2 facing the field 1 so as to protrude toward the field 1 side and is provided in a direction parallel to the winding groove 2c. The cogging force generated by the protrusions 2b is offset by the cogging force generated by each protrusion 2b.

FIG. 8 shows another example of a conventional linear electric machine, where 5 is a field and 6 is an armature. The armature 6 has salient poles 6a disposed facing the field 1 and a winding groove 6c. A plurality of dummy slots 6b are formed in the portion of each salient pole 6a facing the field 1 in a direction parallel to the winding groove 6c, so as to cancel out the cogging force generated by the winding groove 6c. There is.

(Problems to be Solved by the Invention) In conventional linear electric machines, the height of the protrusion provided on the salient pole of the armature needs to be high enough to offset the cogging force due to the winding groove. Alternatively, the depth of the dummy slot formed in the salient pole of the armature needs to be deep enough to offset the cogging force due to the winding groove. As a result, the gap between the salient poles and the field magnet becomes large as a whole, resulting in a problem that the effective magnetic flux decreases and the efficiency deteriorates. In other words, effective magnetic flux and efficiency were sacrificed in order to prevent cogging. 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 has been made to solve these conventional problems, and is capable of reducing cogging force while preventing a decrease in effective magnetic flux and efficiency, and also prevents the winding space from becoming smaller. The purpose is to provide a linear electric machine that can

(Means for Solving the Problems) The present invention includes a field magnetized into multiple poles, and an armature having a winding groove and an end disposed opposite to the field, In a linear electric machine in which one of the above-mentioned field and armature is moved in a straight line relative to the other, the part of the armature that faces the field has a magnetic pole pitch or an integral multiple thereof with respect to the position of the above-mentioned winding groove. It is characterized in that the ultimate surface area at a plurality of locations shifted by an integer multiple of the magnetic pole pitch with respect to the shifted location or the position of the winding groove is made larger than other locations of the salient pole.

(Function) The cogging force generated by the magnetic pole pitch or a portion shifted by an integral multiple of this with respect to the position of the winding groove is larger than the cogging force generated by other portions of the salient pole, and this cogging force and the armature The cogging force generated by the winding groove is canceled 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. 9, 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. Regardless of the pole or south pole, one period of cogging torque is generated each time the iron piece 8 moves 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. 11, 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. 13, 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,
A cogging torque is generated in the core 9 which is the same in phase and magnitude as the cogging torque generated in the iron piece 8 shown in FIG. 9 (see FIG. 10), but opposite only in direction (see FIG. 14). That is, the cogging torque generated is obtained by subtracting the cogging torque of the iron piece 8 shown in FIG. 10 from the cogging torque of the core 9 shown in FIG. 12. Conversely, 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. 15, a similar effect can be obtained by providing a portion of the core 9 of the armature with a protrusion 9b corresponding to the groove 9a. 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. By providing the protrusions 9c of the same size, the phase of the cogging torque generated by the groove 9a and the phase of the cogging torque generated by the protrusion 9c can be aligned, and the two cogging torques cancel each other out. Can be matched. Further, it is not limited to the position one magnetic pole pitch away from the groove 9a, but even if a protrusion 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 protrusion 9c can be aligned with the phase of the cogging torque generated by the protrusion 9c, and the same effect can be obtained.

In the examples shown in FIGS. 15 and 16, the shape and size of the protrusion are the same as the shape and size of the groove,
Although the protrusion was provided at one location, the present invention is not limited to this configuration. As shown in FIG. 17, protrusions 9d and 9e are half the size of the groove 9a.
at the two positions mentioned above, namely the position of the groove 9a and the groove 9.
Even if it is provided at a position one magnetic pole pitch away from a, the cogging torque generated by the groove 9a of the core 9 and the cogging torque generated by the protrusions 9d and 9e can cancel each other out. That is,
The sum of the cogging torques generated by the plurality of protrusions is the same as the cogging torque generated by the grooves, and the cogging torque generated by the plurality of protrusions is It is only necessary that the phase be provided as appropriate so that the phase is 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. 18 is an example of calculating the cogging torque of the core 9 having one groove 9a, and FIG. 19 is an example of calculating the cogging torque of the core 9 having one groove 9a and one protrusion 9c. As is clear from FIGS. 18 and 19, one groove 9a and one protrusion 9
In the case of core 9 with c, groove 9a and protrusion 9
The cogging torques of c 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 FIGS. 1 and 2, reference numeral 11 indicates a field consisting of a flat permanent magnet magnetized with a plurality of poles in the longitudinal direction, and 12 indicates an armature. Armature 12 is field 1
Three salient poles 121 arranged opposite to the field 11 within the range of a pair of magnetic poles, an N pole and an S pole.
Winding grooves 123a, 123b, 123c are provided between these salient poles. Either one of the field 11 and the armature 12 is aligned with the other in the longitudinal direction of the field 11, that is, the armature 1.
It is designed to be able to move linearly in the arrangement direction of each of the two salient poles. FIG. 4 shows the entire embodiment described above, in which the armature 12 is fixed and the field 11 is moved linearly relative to the armature 12 in its longitudinal direction. The field 11 is guided by guide rollers 13 and moves in a straight line.

Each salient pole 121a, 121b, 12 of armature 12
1c is formed with protrusions 122a, 122b, and 122c that protrude on both sides, that is, in a direction perpendicular to the rectilinear movement direction, at the longitudinal center of each of the salient poles, so that the field of each of the salient poles is A portion of the surface facing the salient pole 11 has a larger surface area than other portions of the salient pole. As shown in FIG. 3a, if the magnetic pole pitch of the field 11 is P, each of the salient poles 1
Each protrusion 122a of 21a, 121b, 121c,
122b and 122c are the respective winding grooves 123a,
It is provided at a position shifted by a magnetic pole pitch P from the positions of 123b and 123c. To explain more specifically, the protrusion corresponding to the winding groove 123a is 1
22c, the protrusion corresponding to the winding groove 123b is 12
2a, the protrusion corresponding to the winding groove 123c is 122
b, and the ultimate surface area of the portion where these protrusions are formed is larger than the surface area of the other portions of the salient pole.

According to the above embodiment, cogging force is generated in the portions of the salient poles 121a, 121b, 121c facing the field 11 of the armature 12, whose surface areas are expanded by forming the respective protrusions 122a, 122b, 122c. is larger than the cogging force generated in other parts of the salient poles 121a, 121b, and 121c. The protrusions 122a, 122b, 122c are provided at positions shifted by the magnetic pole pitch P with respect to the positions of the winding grooves 123a, 123b, 123c. As a result, the surface area is expanded by the formation of the protrusions. The cogging force generated in the
The cogging forces generated by the actuators 3a, 123b, and 123c are opposite to each other and cancel each other out, thereby reducing the cogging force.

Furthermore, according to the above embodiment, there is no need to provide a protrusion protruding toward the field side on the surface of each salient pole facing the field, and there is no need to provide a dummy slot. It will not retreat to the child body side. Therefore, the winding space is not limited, and cogging force can be reduced while preventing a decrease in efficiency.

The width of the portion of the armature 12 that faces the field 11 and should have a large surface area, that is, the portion where the protrusions 122a, 122b, 122c are formed in the above embodiment, is basically the width of the winding grooves 123a, 123b, 1
The width of the protrusion 23c may be the same as the width of the winding groove, but even if the phase between the protrusion and the winding groove is slightly shifted, there is a cogging prevention effect, so the width of the protrusion should be the same as the width of the winding groove.
There is no problem even if it is about 0.4 to 2.5 times.

The surface shape of the armature for partially widening the surface area of the portion of the armature facing the field is not limited to the shape of the above embodiment, and may be of the shape shown in FIGS.
It may be modified as shown in d. b is a shape in which a part of the salient pole of the armature is protruded only on one side in the width direction, c
is a shape in which the longitudinal middle part of a salient pole divided into two in the width direction is connected by a protrusion, and d is a shape in which the longitudinal middle part of a salient pole divided in half in the width direction is connected by a protrusion, and a part of the salient pole It has a shape in which it protrudes only on one side in the width direction. In order to obtain armatures of various shapes, cores of different lengths may be combined and laminated, or a core and a yoke plate with a protrusion may be combined.

In the embodiment described above, each salient pole 121a, 1
The forming portions of the protrusions 122a, 122b, 122c for partially increasing the surface area of the wires 21b, 121c are formed in the respective winding grooves 123a, 123b, 123.
The position of each salient pole was shifted by the magnetic pole pitch P from the position of c, but as is clear from the cogging reduction principle already explained with reference to FIGS. It is also possible to form the part at a position shifted by an integral multiple of the magnetic pole pitch P, for example, 2P or 3P, with respect to the position of each winding groove.

Next, another embodiment of the present invention will be described. In FIG. 5, reference numeral 21 denotes a field magnetized with multiple poles;
22 is an armature. The armature 22 has three salient poles 2
21a, 221b, 221c and winding grooves 223a, 223b, 223c are provided between these salient poles.
The three salient poles are located within the range of the four magnetic poles of the field 21. Each salient pole 2 above
Protrusions 222a, 222 partially extend in the width direction, that is, in a direction orthogonal to the rectilinear movement direction, at the portions of 21a, 221b, and 221c that face the field 21.
By providing three portions b and 222c, the surface area of that portion is larger than that of the other portions of the salient pole. Assuming that the pole pitch of the field 21 is P, the protrusion is provided at a position shifted from the position of each winding groove by the magnetic pole pitch P and its integral multiples 2P and 3P. That is, in this embodiment, a plurality of portions with large surface areas are provided for one winding groove.

More specifically, in FIG.
The protrusion 222a (the left end of the salient pole 221a) is placed at a position a magnetic pole pitch P away from the groove 223b to the left, the protrusion 222b (the right end of the salient pole 221b) is placed at a position a magnetic pole pitch P away to the right, and further to the right. A protrusion 222c (center of the salient pole 221c) is provided at a location twice the magnetic pole pitch P. Each of the above protrusions 222
The size of the grooves a, 222b, and 222c is about one-third that of the groove 223b. The three protrusions 222 act against the cogging force generated by the groove 223b.
The cogging forces generated by a, 222b, and 222c have the same phase, about one-third the magnitude, and opposite directions. Therefore, the cogging force generated by the groove 223b is applied to the three protrusions 222.
This is canceled out by the cogging force generated by a, 222b, and 222c.

Similarly, for the groove 223c of the armature 22, the protrusion 222c on the right side of the salient pole 221c, the protrusion 222c on the right side of the salient pole 221c,
A protrusion 222b on the left side of the salient pole 21b and a protrusion 222a in the center of the salient pole 221a are provided at positions shifted by an integral multiple of the magnetic pole pitch P, and the cogging force generated by these protrusions causes the groove 223c to It is designed to cancel out the cogging force that occurs due to twisting. Also, for the groove 223a of the armature 22,
The protrusions 222b, salient poles 222c, and salient poles 222b are provided at positions shifted by an integral multiple of the magnetic pole pitch P, and the cogging force generated by these protrusions causes the cogging force generated by the grooves 223a to be reduced. It is beginning to cancel out the

As described above, the number of protrusions is not limited to three pairs, and can be provided as appropriate depending on the size of the protrusions.

In the case of the above-mentioned embodiment, the cogging force reduction effect is achieved similarly to the case of the above-mentioned embodiment. In the case of this embodiment, since there are multiple parts with a wide surface area for one winding groove, the ratio of the area of the wide part to the area of the narrow part can be reduced, and the overall width can be reduced. I can do it.

FIG. 6 shows various modifications of the armature for providing a plurality of portions with large surface areas for one winding groove. a is a shape in which a part of the armature facing the field is protruded only to one side in the width direction; b is a shape in which the armature facing the field is divided into two in the width direction and connected at multiple points; C has a shape in which the portion of the armature facing the field is divided into two in the width direction, connected at a plurality of points, and protrudes only on one side in the width direction. Specific means for obtaining armatures of various shapes as described above can be obtained by combining cores of different lengths or by combining cores and yoke plates.

In addition, the width direction dimension of the part with a wide surface area of the armature is basically twice the size of the ground part of the salient pole if the wide part has the same number as the winding grooves, or the width of the wide part. If the number of the wide portions is twice that of the winding grooves, the dimension is 1.5 times that of other parts of the salient pole, and if the number of the wide parts is three times that of the winding grooves, the dimension is 1.33 times that of other parts of the salient pole. It is preferable to reduce the cogging force to approximately the same size. However, the configuration of the magnetic circuit, such as the widthwise dimension of the field, differs from one individual to another, and as mentioned above, the linear dimension of the protrusion to partially widen the armature surface area cannot be uniformly determined. However, since various other design conditions differ from one another, the optimum width and longitudinal dimensions of the large surface area portion of the armature differ depending on the above-mentioned conditions.

In the linear electric machine according to the present invention, any one of the field and the armature may move linearly relative to the other.

(Effects of the Invention) According to the present invention, the surface area of the portion of the armature that faces the field is partially widened, and the cogging force generated in this portion cancels out the cogging force generated in the winding groove. Therefore, there is no need to provide a protrusion facing the field on the armature surface facing the field,
There is no need to provide a dummy slot, and the cogging force can be reduced while preventing a decrease in effective magnetic flux and efficiency. Furthermore, since the winding space can be increased, winding is easier 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]

Fig. 1 is a side view showing an embodiment of the linear electric machine according to the present invention, Fig. 2 is a front view of the armature in the above embodiment as seen from the field side, and Fig. 3 is applicable to the above embodiment. 4 is a perspective view of the above-mentioned embodiment, and FIG. 5 is a diagram showing the relationship between the field and the armature showing another embodiment of the linear electric machine according to the present invention. Fig. 6 is a front view showing various modifications of the armature applicable to the above embodiment, Fig. 7 is a front view showing an example of a conventional linear electric machine, and Fig. 8 is a front view showing another example of a conventional linear electric machine. 9 is a plan view showing a state in which an iron piece is placed in the magnet, FIG. 10 is a waveform diagram showing the cogging torque generated in the same iron piece, and FIG. 11 is a diagram showing a core with a circular cross section in the magnet. FIG. 12 is a waveform diagram showing the cogging torque generated in the same core. FIG. 13 is a plan view showing the core with a circular cross section and grooves being placed in the magnet. Figure 14 is a waveform diagram showing the cogging torque generated in the same core as above, Figure 15 is a developed diagram showing the relationship between the grooved core and the magnet, and Figure 16 is a developed diagram showing the relationship between the core with grooves and protrusions and the magnet. 17 is a developed view showing the relationship between the core with grooves and a plurality of protrusions and the magnet, FIG. 18 is a waveform diagram showing the relationship between the armature core with grooves, magnetic flux, and cogging torque, and FIG.
The figure is a waveform diagram showing the relationship between an armature core with grooves and protrusions, magnetic flux, and cogging torque. 11, 21... Field, 12, 22... Armature,
121a, 121b, 121c, 221a, 22
1b, 221c... salient pole, 123a, 123b,
123c, 223a, 223b, 223c... Grooves for winding.

Claims (1)

[Claims] 1.Equipped with a field magnetized to multiple poles and an armature having a winding groove and salient poles arranged opposite to the field, and one of the field and the armature In a linear electric machine that moves in a straight line relative to the other, a part of the armature that faces the field and is shifted from the magnetic pole pitch or an integral multiple of this position with respect to the position of the winding groove, or a position of the winding groove. On the other hand, a linear electric machine characterized in that the surface area of the salient pole at the magnetic pole pitch and a plurality of parts shifted by an integral multiple of the pitch is made larger than other parts of the salient pole.