JPH0456545B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a linear motor in which a mover moves linearly.

FIG. 1 is a configuration diagram showing an example of a conventional linear motor, where A is a longitudinal sectional view, B is a sectional view taken along the line C-C of A,
C is a cross-sectional view taken along line A-A of A, and D is a cross-sectional view taken along line B-B. In FIG. 1, 1 is a running path made of magnetic material, and 2 is a movable element facing this running path with a slight gap in between. In this example, a three-phase linear motor is shown. The mover 2 has three field legs 211, 212, 213, 221, 222, 2, respectively.
A pair of iron cores 21, 22 having 23, a permanent magnet 20 which is interposed between the pair of iron cores 21, 22 and has the role of supplying bias magnetic flux to the above-mentioned slight gap, and a pair of iron cores 21, 22. Field legs 211, 221 and 212, 222 and 21 adjacent to each other
It is composed of three excitation windings 31, 32, 33 wound over 3,223 wires. Furthermore, three magnetic pole teeth a, b, and c having the same pitch P as the tooth pitch provided in the running path 1 are provided at the end of each field leg facing the running path 1. Here, iron core 21,
Of the 22 field legs, 21 are installed on the same core.
The magnetic pole tooth phases of 1, 212, 213, 221, 222, and 223 are (N±n/m)P [however,
N is an integer, m is the number of phases of the linear motor, n is m>n
(5+1/3)P] in this example, and the iron core 21
The magnetic pole teeth provided on the respective adjacent field legs of and 22 are in the same phase. The running path 1 has magnetic pole tooth rows 11 and 12 of the same pitch P as the magnetic pole teeth provided on the iron cores 21 and 22 of the mover 2, as shown in FIG. 1D,
The magnetic pole tooth row 11 and the magnetic pole tooth row 12 are arranged with a phase difference of 1/2P in the moving direction of the movable element 2.

In the device configured in this manner, the permanent magnet 20 is magnetized in the direction shown in FIG. The magnetic pole teeth of the iron core 22 and each field leg 221 pass through the magnetic pole tooth row 11 of the running path 1, which faces the magnetic pole teeth a, b, and c through a small gap, and pass through the magnetic pole tooth row 12 through a small gap. , 222, 223 through the permanent magnet 20
Return to In other words, the magnetic pole teeth of the movable element 2 and the running path 1
Bias magnetic flux exists in the air gap between the magnetic pole teeth. Now, when an excitation current is passed through the excitation winding 31, the magnetic flux due to this excitation current is superimposed on the bias magnetic flux. Now, when an excitation current is passed through the excitation winding 31 in a direction in which the magnetic flux between the field legs 211 on the iron core 21 side and the running path 1 increases, the magnetic flux between the field legs 221 on the iron core 22 side and the running path 1 increases. The magnetic flux of decreases. As a result, the field legs 211 of the mover 2 and the travel path 1 are attracted to each other, and the mover 2 is moved to the position shown in FIG.
is retained.

Next, when an excitation current is passed through the excitation winding 32 in a direction in which the magnetic flux between the field leg 212 on the iron core 21 side and the travel path 1 increases, the two attract each other, so that the movable element 2 moves to the left. Here, the amount of movement of the mover 2 is 1/3P because the phase between the magnetic pole teeth a, b, c of the field leg 211 and the magnetic pole teeth a, b, c of the field leg 212 is 1/3P. / 3P will be moved.

Hereinafter, in the same manner, the excitation windings 33, 31, 3
If the excitation current is applied sequentially as 2, 33, . . . , the mover will sequentially move to the left with 1/3P as the minimum movement amount. Furthermore, if the excitation current is applied to the excitation windings 33, 32, and 31 in this order, the movable element 2 moves to the right.

On the other hand, if the direction of the excitation current flowing through the excitation windings 31, 32, and 33 is reversed from the above case, the magnetic flux between the field legs 221 and the running path 1 increases in FIG. This will result in a deal. Therefore, if an excitation current is sequentially applied to the excitation windings 32, 33, 31, . . . in the opposite direction to the above case, the movable element 2 similarly moves to the left with 1/3P as the minimum movement amount. In addition, excitation windings 33, 32, 31,...
If a current is applied in the opposite direction to that in the above case in this order, the mover 2 moves to the right with 1/3P as the minimum amount of hyperactivity. Here, since the magnetic pole tooth rows 11 and 12 of the running path 1 are formed with a tooth phase shifted by 1/2P, the flow direction of the excitation current flowing through the excitation winding is the positive direction and the negative direction. (in the opposite direction), the stop positions of the movers 2 do not overlap with each other and are shifted by 1/6P. In other words, by switching the excitation current flowing through the excitation windings 31, 32, and 33 and changing the direction of the excitation current to sequentially excite the excitation windings, the minimum movement amount 1/
Mover 2 moves at 6P. Furthermore, although the above explanation has been made using only single-phase excitation, the thrust can be increased by using multi-phase excitation.

By the way, in order to improve the thrust of this type of linear motor, it is very effective to increase the bias magnetic flux between the magnetic pole teeth provided on the iron core of the mover and the magnetic pole teeth provided on the running path. be. One way to increase the bias magnetic flux is to increase the total amount of magnetic flux generated by the permanent magnets that provide the bias magnetic flux.Another method is to increase the total amount of magnetic flux generated by the permanent magnets that does not contribute to the thrust of the linear motor. There is a need to reduce magnetic flux (leakage flux) as much as possible.

From the above points, if we look at the conventional example of the structure as shown in FIG.
Pairs of field legs 211 and 221, 212 and 222, 2
Since the distance W ₁ between 13 and 223 is narrow, the amount of leakage magnetic flux between them is very large, and accounts for the largest proportion of the leakage flux in the entire magnetic circuit.
As a result, the magnetic flux of the permanent magnet is not used effectively, and there is a lot of waste, so it cannot be said that the motor is efficient.
Here, if the distance W ₁ is increased, it is possible to reduce the leakage magnetic flux, but the width dimension W ₂ of the running path 1 must also be increased accordingly. The increase in the width dimension W ₂ of the running path 1 is the increase in the width dimension W 2 of the running path 1.
, the increase in road weight is large. Therefore, a device incorporating this motor inevitably increases in weight. In addition, in XY plotters, etc., which are configured by combining these motors, the motor on one axis moves and positions the motor on the other axis for each running path, so the increase in weight of the running path has a large impact on the plotting speed of the plotter. Adversely affect.

Next, the machining of the magnetic pole teeth of the conventional movable element shown in FIG. 1 has the disadvantage of poor dimensional accuracy. Generally, when machining the magnetic pole teeth of a mover, the machining blade is sent one magnetic pole tooth pitch at a time to form the teeth, but when the number of phases of a linear motor increases to 5, 6, etc., the teeth are formed on the same core. The number of types of magnetic pole teeth with different phases increases to 5, 6, etc., and the phase difference also increases to 2π/5,
Since it is as fine as 2π/6, etc., it is necessary to change the feed pitch of the machining blade many times during machining, making it difficult to achieve machining accuracy.As a result, the positioning accuracy of the linear motor deteriorates. Cheap.

The first object of the present invention is to provide a linear linear system with a novel structure that achieves high efficiency and high thrust without increasing the width of the running track or its weight while significantly reducing the leakage magnetic flux mentioned above. Our goal is to provide motors. A second object of the present invention is to provide a linear motor with a novel structure that makes it easier to form the magnetic pole teeth of the mover and stator (running path), and as a result, improves the mechanical accuracy and positioning accuracy. There is a particular thing. Therefore, the linear motor of the present invention has a pair of iron cores having a pitch of P and a plurality of field legs in which magnetic pole teeth of the same phase are formed. /2・
Means for supplying a bias magnetic flux passing through the pair of iron cores by arranging the plurality of field legs of each of the pair of iron cores in a direction orthogonal to the moving direction of the movable element; The movable element includes a means for exciting the field legs, and a slit member having a large number of slits is fixed to a base made of a magnetic material on a traveling path along which the movable element moves. A plurality of rows of magnetic pole teeth are provided along the moving direction of the movable element on a surface facing the former movable element, and the pitch of each magnetic pole tooth of the magnetic pole tooth array is the same as that of the magnetic pole teeth of the aforementioned movable element, and The pitch phase between each of the magnetic pole tooth rows is shifted by n/m·P (where m is the number of phases of the linear motor and n is an integer with a relationship of m>n) in the moving direction of the movable element. Adopts a new structure. Examples thereof will be described in detail below with reference to the drawings.

FIG. 2 is a configuration diagram showing one embodiment of the present invention, and A
B is a sectional view taken along the line D-D of A, C is a sectional view taken along the line E-E of A, and D is a sectional view taken along the line FF of A.

In this FIG. 2, the mover 5 has a plurality of field legs (511, 512, 512 and 5
21, 522, 523), a pair of iron cores 51, 52, a permanent magnet 50 interposed between the pair of iron cores 51, 52 and serving to supply bias magnetic flux, and a pair of iron cores 51, 52 adjacent field legs 511 and 521 (512 and 52
It is composed of a plurality of excitation windings (up to now, three, 61, 62, and 63) wound over the coils 2, 513, and 523). In addition, each field leg (51
1,512,513,521,522,523)
A plurality of magnetic pole teeth of pitch P are formed at the end facing the running path, and the phase relationship of each magnetic pole tooth is as shown in Fig. 2C.
As shown in FIG.
13 are in the same phase, and the magnetic pole teeth provided in the field legs 521, 522, 523 of the iron core 52 are in the same phase. , 513 and 523) are arranged with a phase shift of 1/2·P. Specifically, as shown in FIG. 2C, the distance relationship between the magnetic pole teeth provided on the iron core 51 and the magnetic pole teeth provided on the iron core 52 is (k+1/2)·P (k is a positive integer). That's what I do. Also, driving route 4
is made of a magnetic material, and has the same pitch P as the magnetic pole teeth of the movable element 5 on the surface facing the magnetic pole teeth provided on the movable element 5.
A plurality of magnetic pole teeth are provided. Here, the magnetic pole teeth of the running path 4 are arranged in a plurality of rows (in this embodiment, three rows 41, 42, and 43) along the moving direction of the movable element 5.
There is a magnetic pole tooth row 41, 42,
43 has a phase relationship of n/ in the moving direction of the mover 5.
The magnetic pole tooth rows 41 and 42 (42 and 43, 43 and 41) are arranged with a shift of m·P (m is the number of phases of the linear motor, and n is an integer with the relationship m>n).
They are arranged with a 1/3P phase shift.

In the linear motor configured as described above, if the permanent magnet 50 is magnetized in the direction shown in FIG. Magnetic flux is generated in the direction shown in . In other words, bias magnetic flux exists in the directions of the iron core 51, the running path 4, and the iron core 52. Now, field leg 5
When an excitation current is passed through the excitation winding 61 wound around the coils 11 and 521, the magnetic flux generated by this excitation current is superimposed on the bias magnetic flux, and the magnetic flux is generated between the field leg 511 and the magnetic pole tooth row 41 of the running path 4. The magnetic flux between the field leg 521 and the magnetic pole tooth row 41 of the travel path 4 decreases. As a result, the field leg 511 of the mover 5
and the magnetic pole tooth row 41 of the running path 4 attract each other,
The movable element 5 is held at the position shown in FIG. 2A, where the reluctance of the air gap is the smallest. Next, when an excitation current is passed through the excitation windings wound around the field legs 512 and 522, this time the field legs 512 and the running path 4
The magnetic flux between the movable element 5 and the magnetic pole tooth row 42 increases and they attract each other, so the movable element 5 moves to the left. Here, the amount of movement of the mover 5 is the magnetic pole tooth row 4 provided on the travel path.
Since the phases 1 and 42 are shifted by 1/2P in the direction of movement of the movable element, it moves by 1/3P. Similarly, the excitation windings 63, 6
If the excitation current is passed sequentially as 1, 62, 63, etc.,
The movable element 5 sequentially moves to the left with 1/3·P as the minimum movement amount. In addition, excitation windings 63, 62, 6
If the excitation current is applied in the order of 1, . . . , the mover 5 moves to the right.

On the other hand, if the direction of the excitation current flowing through the excitation windings 61, 62, and 63 is reversed from the above case, the iron core 5
The magnetic flux between the field legs 521, 522, 523 of No. 2 and the magnetic pole tooth rows 41, 42, 43 of the running path 4 increases, and they are attracted to each other. Therefore, if an excitation current in the opposite direction to that in the above case is sequentially applied to the excitation windings 61, 62, 63, . Further, if a current is applied in the opposite direction to the above case in the order of the excitation windings 63, 62, 61, . . . , the movable element 5 moves to the right with a minimum movement amount of 1/3P. Here, the phases of the magnetic pole teeth provided on the field legs 511 and 512 (512 and 522, 513 and 523) of the mover 5 are shifted by 1/2·P in the moving direction of the mover 5. Therefore, the stop positions of the mover 5 do not overlap with each other, but are shifted by 1/6P when the excitation current flows in the excitation winding in the positive direction and in the negative direction (reverse direction). It turns out. In other words, by switching the excitation current flowing through the excitation windings 61, 62, and 63 and changing the direction of the excitation current to sequentially excite the excitation windings, the mover 5 moves with a minimum movement amount of 1/6P. . Also,
In the above explanation, only single-phase excitation has been explained, but it goes without saying that by using multi-phase excitation, the thrust can be increased in the same way as in the conventional example explained in FIG. 1.

Next, the structural features of the linear motor of the present invention will be explained.

In FIG. 2, the distance W between the pair of iron cores 51 and 52 can be increased. By widening this W, the entangled magnetic flux from the field leg of the iron core 51 of the mover 5 to the field leg of the iron core 52 can be extremely reduced, so that the magnetic flux generated by the magnetic magnet 50 can be effectively used. can be used. For this reason, the bias magnetic flux increases, leading to an improvement in thrust. In addition, in the case of this structure, since W is the dimension in the moving direction of the mover,
The width of the running track does not change, and the weight of the running track has almost no effect.

In the linear motor of the present invention, the opposing area between the magnetic pole teeth provided on the pair of iron cores 51 and 52 of the mover 5 and the magnetic pole teeth provided on the traveling path is such that although the width of the magnetic pole teeth becomes narrow, Since the number of sheets can be increased very easily in the moving direction of the mover, it can be designed freely.
Therefore, it is easy to avoid magnetic saturation caused by an excessive increase in bias magnetic flux. Further, even if the number of magnetic pole teeth of the mover is increased in the moving direction, the width of the running path does not change at all, so there is almost no increase in the weight of the running path.

As described above, the linear motor of the present invention has the advantage of being able to increase efficiency and increase thrust, and thereby not increasing the weight of the running path. According to the inventor's prototype, the linear motor of the present invention has the same traveling path width and weight as the conventional example, and the thrust force is 30.
It has been confirmed that the amount increases by 40%. Therefore, as mentioned above, the linear motor of the present invention can be said to be most suitable for XY plotters and the like.

Furthermore, the structure of the movable element 5 of the linear motor of the present invention is very advantageous in contrast to the drawback that the machining accuracy of the movable element magnetic pole teeth is difficult to achieve in the conventional example. In other words, the phases of the magnetic pole teeth provided on the field legs of the same iron core among the plurality of field legs of the mover 5 are the same, so no matter how many phases the linear motor increases, the phase remains the same. The magnetic pole teeth provided on the iron cores are of one type in terms of phase, and the feed pitch of the machining blade is changed only by the phase difference of 1/2 and 1/2 between the pair of iron cores.
It is only necessary to provide P. Therefore, the structure of the movable element of the linear motor of the present invention is very excellent in that it can improve workability in machining magnetic pole teeth and easily increase dimensional accuracy.

In the above explanation, the linear motor of the present invention operates as a step motor, but the advantages of the present invention can also be obtained even if it is provided with a position detection means, a non-contact power supply means, etc., and used as an electronic commutator linear motor. It doesn't hurt anything.

3 and 4 are main part configuration diagrams showing other embodiments of the linear motor of the present invention. In the figure, the same components as those in the embodiment shown in FIG. 2 are given the same numbers.

In the embodiment shown in FIG. 2, a permanent magnet 50 is interposed between a pair of iron cores 51 and 52 to provide a bias magnetic flux, but as shown in FIG. It is also possible to wind the winding 60 around the magnetic path, thereby applying a bias magnetic flux. In addition, a pair of field legs 511 and 5
Excitation windings 61, 62, 63 wound across 21 (512 and 5222, 513 and 523)
As shown in FIG. 4, each field leg 511, 521
The windings 611 and 612 may be wound separately and connected in series, or the excitation current may be passed through these separately. Field legs 512, 52
The same applies to 2,513,523.

Here, the distance W between the pair of iron cores 51 and 52 is made extremely wide, and the pair of field legs 511 and 512
If the excitation winding is wound across (512 and 522, 513 and 523), the length of the excitation winding becomes longer and the copper loss increases. From the viewpoint of efficiency of the linear motor, it is desirable that the copper loss be small. The embodiment shown in FIG. 4 is very effective in reducing copper loss because the excitation winding length can be shortened.

FIG. 5 shows an embodiment for easily and accurately realizing the structure of the running path 4 of the embodiment of the linear motor of the present invention shown in FIGS. 2, 3, and 4. In Fig. 5, A is a plan view of the running path, and B is G- of A.
It is a sectional view taken along the G line.

In FIG. 5, a thin plate member 71 (hereinafter referred to as
By fixing this etched plate (referred to as an etching plate) to a base plate 72 made of a magnetic material, magnetic pole teeth are equivalently formed and the running path 4 is realized. Here, the etching plate 71 has slits arranged in multiple rows (711, 712, 71 in this embodiment) along the moving direction of the movable element 5.
3), and slit rows 711, 712,
The phase relationship of 713 is n/m·P in the moving direction of the movable element (where m is the number of phases of the linear motor,
n is an integer satisfying m>n, and in this embodiment, they are configured to be shifted from each other by 1/3·P).

The dimensional accuracy of each slit in the etching plate 71 is as follows:
The etching accuracy depends on the material and thickness t of the thin plate to be etched. Therefore, as the number of phases of the linear motor increases to 5, 6, etc., the magnetic pole tooth row of the running path 4 increases to 5, 6, etc.
Even if the number of rows increases and becomes more complex, the workability of manufacturing the etched plate remains the same, and it can be manufactured very easily without compromising accuracy. Furthermore, although the slits in the etched plate of this embodiment pass through the thin plate, it goes without saying that half-etching may also be used, and has the same advantages in accuracy and ease of manufacture.

Although not shown, the above-mentioned advantages will not be lost even if the running path 4 is manufactured by directly half-etching the base 72 made of a magnetic material without using the etching plate 71.

[Brief explanation of drawings]

Figure 1 A, B, C, D is a sectional view of each part showing an example of a conventional linear motor, Figure 2 A, B, C, D
is a sectional view of each part showing one embodiment of the present invention, FIGS. 3 and 4 are main part configuration diagrams showing other embodiments of the linear motor of the present invention, and FIGS. 5A and B are diagrams used in the present invention. FIG. 2 is a plan view and a sectional view of a main part showing an example of a possible running path. 4...Travel road, 41, 42, 43, 711, 7
12,713...Magnetic pole tooth row, 5...Mover, 50
... Permanent magnet, 501 ... Magnetic path of permanent magnet, 5
1,52...Pair of iron cores, 511,512,51
3,521,522,523...field leg, 60...
...Excitation winding for bias magnetic flux supply, 61, 62,
63... Excitation winding, 71... Slit member (etching plate), 72... Base made of magnetic material.

Claims (1)

[Claims] 1 It has a pair of iron cores with a plurality of field legs forming magnetic pole teeth of the same phase with pitch P, and the magnetic pole tooth phases of these pair of iron cores are shifted by 1/2・P in the moving direction of the mover. a plurality of field legs of each of the pair of iron cores are arranged in a direction perpendicular to the moving direction of the movable element, and supplying a bias magnetic flux passing through the pair of iron cores; The movable element includes a means for exciting the legs, and a slit member having a large number of slits and a base made of a magnetic material are fixed to the travel path along which the movable element moves. A plurality of rows of magnetic pole teeth are provided along the moving direction of the first mover on the surface facing the first mover, and the pitch of each magnetic pole tooth of the first half of the magnetic pole teeth is the same as that of the magnetic pole teeth of the first mover, and each of the above-mentioned The pitch phase between the magnetic pole tooth rows is n/m・P in the moving direction of the movable element (where m is the number of phases of the linear motor, and n is an integer with the relationship m>n).
A linear motor characterized by being shifted in steps.