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Claims  |
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What is claimed is:
1. A linear motor, comprising:
field magnets spaced at equal intervals from one another and having an
equal pitch; and
a rotor arranged to move opposite to said field magnets and including an
armature core divided into at least three block cores equally spaced apart
from one another,
each of said block cores including armature coils wound in the form of a
concentrated winding and teeth, said armature coils of said block cores
being wound around said teeth with their phases shifted by an electrical
angle corresponding to the distance between said block cores.
2. A linear motor as set forth in claim 1, wherein said at least three
block cores comprise a first block core, a second block core, and a third
block core, each of said first, second and third block cores having nine
teeth and a length equivalent to eight times the pitch of said field
magnets, said teeth being arranged at equal pitches, the distance between
said first, second and third block cores being equivalent to two-thirds of
the pitch of said field magnets, said teeth of said first, second and
third block cores being grouped three by three, said armature coils of
said first block core being wound in the order of U phase, V phase and W
phase in respective groups thereof, said armature coils of said second
block core being wound in the order of V phase, W phase and U phase in
respective groups thereof, said armature coils of said third block core
being wound in the order of W phase, U phase and V phase in respective
groups thereof, said armature coils being wound in the form of a balanced
three-phase winding with a difference of 120.degree. in phase.
3. A linear motor as set forth in claim 1, wherein said at least three
block cores comprise a first block core, a second block core, and a third
block core, each of said first, second and third block cores having nine
teeth and a length equivalent to eight times the pitch of said field
magnets, said teeth being arranged at equal pitches, the distance between
said first, second and third block cores being equivalent to one-third of
the pitch of said field magnets, said teeth of said first, second and
third block cores being grouped three by three, said armature coils of
said first block core being wound in the order of U phase, V phase and W
phase in respective groups thereof, said armature coils of said second
block core being wound in the order of W phase, U phase and V phase in
respective groups thereof with the winding direction reversed from the
winding direction of said armature coils of said first block core, said
armature coils of said third block core being wound in the order of V
phase, W phase and U phase in respective groups thereof in the same
winding direction as that of said first block core, said armature coils
being wound in the form of a balanced three-phase winding with a
difference of 60.degree. in phase.
4. A linear motor as set forth in claim 1, wherein said at least three
block cores comprise a first block core having nine teeth and a length
equivalent to eight times the pitch of said field magnets, said teeth of
said first block core being arranged at equal pitches, a second block core
having eighteen teeth and a length equivalent to sixteen times the pitch
of said field magnets, said teeth of said second block core being arranged
at equal pitches, and a third block core similar to said first block core,
said first, second and third block cores being spaced apart from one
another by a distance equivalent to two-thirds of the pitch of said field
magnets, said teeth in said first, second and third block cores being
grouped three by three, said armature coils of said first block core being
wound in the order of U phase, V phase and W phase in respective groups
thereof, said armature coils of said second block core being wound
repeatedly two times in the order of V phase, W phase and U phase in
respective groups thereof, said armature coils of said third block core
being wound in the order of W phase, U phase and V phase in respective
groups thereof, said armature coils being connected in a balanced
three-phase winding with a difference of 120.degree. in phase.
5. A linear motor as set forth in claim 1, wherein said at least three
block cores comprise a first block core having nine teeth and a length
equivalent to eight times the pitch of said field magnets, said teeth of
said first block core being arranged at equal pitches, a second block core
having eighteen teeth and a length equivalent to sixteen times the pitch
of said field magnets, said teeth of said second block core being arranged
at equal pitches, and a third block core similar to said first block core,
said first, second and third block cores being spaced apart from one
another by a distance equivalent to two-thirds of the pitch of said field
magnets, said teeth in said first, second and third block cores being
grouped three by three, said armature coils of said first block core being
wound in the order of U phase, V phase and W phase in respective groups
thereof, said armature coils of said second block core being wound
repeatedly two times in the order of W phase, V phase and U phase in
respective groups thereof, said armature coils of said third block core
being wound in the order of V phase, U phase and W phase in respective
groups thereof, said armature coils being connected in a balanced
three-phase winding with a difference of 120.degree. in phase.
6. A linear motor as set forth in claim 1, wherein said at least three
block cores comprise a first block core, a second block core and a third
block core being spaced apart from one another by a distance equivalent to
one-third of the pitch of said field magnets, said teeth of said first,
second and third block cores being grouped three by three, said armature
coils of said first block core being wound in the order of U phase, V
phase and W phase in respective groups, said armature coils of said second
block core being wound in the order of W phase, U phase and V phase
repeatedly two times in respective groups with the winding direction
reversed, said armature coils of said third block core being wound in the
order of V phase, W phase and U phase in the same winding direction as
that of the first block core, said armature coils being connected in a
balanced three-phase winding with a difference of 60.degree. in phase.
7. A linear motor as set forth in claim 1, wherein said at least three
block cores comprise a first block core, a second block core and a third
block core being spaced apart from one another by a distance equivalent to
one-third of the pitch of said field magnets, said teeth of said first,
second and third block cores being grouped three by three, said armature
coils of said first block core being wound in the order of U phase, V
phase and W phase in respective groups, said armature coils of said second
block core being wound in the order of V phase, U phase and W phase
repeatedly two times in respective groups with the winding direction
reversed, said armature coils of said third block core being wound in the
order of W phase, V phase and U phase in the same winding direction as
that of said first block core, said armature coils being connected in a
balanced three-phase winding with a difference of 60.degree. in phase.
8. A linear motor as set forth in claim 1, further comprising a spacer made
of a non-magnetic substance arranged between adjacent ones of said at
least three block cores.
9. A linear motor as set forth in claim 1, further comprising a fixing
portion, said field magnets being attached to said fixing portion.
10. A linear motor as set forth in claim 1, wherein the distance between
said at least three block cores is determined by dividing the electrical
angle of the pitch of said field magnets by the number of block cores and
multiplying the result by an integer less than the number of block cores.
11. A linear motor as set forth in claim 10, wherein said at least three
block cores consists of three block cores and the electrical angle of the
pitch of said field magnets is 180 degrees such that the distance between
said three block cores is 60 degrees which translates into 1/3 of the
pitch of said field magnets or 120 degrees which translates into 2/3 of
the pitch of said field magnets.
12. A linear motor as set forth in claim 1, wherein said at least three
block cores are equal in length.
13. A linear motor as set forth in claim 1, wherein a thrust direction is
defined as a direction of movement of said rotor relative to said field
magnets, said at least three block cores being arranged linearly in the
thrust direction.
14. A linear motor as set forth in claim 1, wherein said at least three
block cores comprise a first block core having nine teeth and a length
equivalent to eight times the pitch of said field magnets, said teeth of
said first block core being arranged at equal pitches, a second block core
having eighteen teeth and a length equivalent to sixteen times the pitch
of said field magnets, said teeth of said second block core being arranged
at equal pitches, and a third block core similar to said first block core,
the distance between said first, second and third block cores being
equivalent to two-thirds of the pitch of said field magnets, said teeth in
said first, second and third block cores being grouped three by three,
said armature coils of said first block core being wound in the order of U
phase, V phase and W phase in respective groups thereof, said armature
coils of said second block core being wound repeatedly two times in the
order of V phase, W phase and U phase in respective groups thereof, said
armature coils of said third block core being wound in the order of W
phase, U phase and V phase in respective groups thereof.
15. A linear motor as set forth in any one of claims 1-3 and 4-7, further
comprising a temperature sensor arranged between adjacent ones of said at
least three block cores to detect the temperature of an intermediate
portion of said armature coils alongside said temperature sensor.
16. A linear motor as set forth in claim 15, wherein said temperature
sensor is arranged in a resin-molded armature.
17. A linear motor comprising:
field magnets spaced at equal intervals from one another and having an
equal pitch; and
a rotor arranged to move opposite to said field magnets and including an
armature core divided into first and second block cores,
each of said block cores including armature coils wound in the form of a
concentrated winding and having nine teeth arranged at equal pitch, said
armature coils of said block cores being wound with their phases shifted
by an electrical angle corresponding to a distance between said block
cores, said block cores having a length equivalent to eight times the
pitch of said field magnets, the distance between said block cores being
equivalent to one half of the pitch of said field magnets, said armature
coils of said first block core being wound in the order of U phase, V
phase and W phase with said teeth being grouped three by three, said
armature coils of said second block core being arranged such that said
second block core has one coil of V phase wound around a first tooth, a
coil of W phase wound around the next three teeth, a coil of U phase wound
around the next three teeth, and a coil of V phase wound around the
remaining two teeth, said armature coils being wound in the form of a
balanced three-phase winding with a difference of 90.degree. in phase.
18. A linear motor, comprising:
field magnets spaced at equal intervals from one another and having an
equal pitch; and
a rotor arranged to move opposite to said field magnets and including an
armature core divided into first and second block cores,
each of said first and second block cores including armature coils wound in
the form of a concentrated winding and having nine teeth arranged at equal
pitch, said armature coils of said first and second block cores being
wound with their phases shifted by an electrical angle corresponding to a
distance between said block cores, said block cores having a length
equivalent to eight times the pitch of said field magnets, the distance
between said block cores being equivalent to one half of the pitch of said
field magnets, said armature coils of said first block core being wound in
the order of U phase, V phase and W phase with said teeth grouped three by
three, said armature coils of said second block core being wound in the
order of V phase, W phase and U phase with said teeth grouped three by
three, said armature coils being wound in the form of a balanced
three-phase winding with a difference of 90.degree. in phase.
19. A linear motor as set forth in claim 17 or 18, wherein the same phase
coils of said first block core and said second block core are connected in
series.
20. A linear motor as set forth in claim 17 or 18, further comprising a
spacer made of a non-magnetic material arranged between said first and
second block cores.
21. A linear motor as set forth in claim 17 or 18, further comprising a
temperature sensor arranged between said first and second block cores to
detect the temperature of an intermediate portion of said armature coils
alongside said temperature sensor.
22. A linear motor as set forth in claim 21, wherein said temperature
sensor is arranged in a resin-molded armature.
23. A linear motor as set forth in any one of claims 1-5 and 4-7, wherein
said teeth of said block cores each have an iron relay portion for
coupling said teeth together, said iron relay portion including an
engagement projection formed at one side of said tooth and a fitting
portion formed at the other side of said tooth to be engaged with said
engagement projection, said teeth being coupled together by engaging said
engagement portion of one of said teeth with said fitting portion of
another of said teeth.
24. A linear motor, comprising:
field magnets spaced at equal intervals from one another and having an
equal pitch; and
a rotor arranged to move in a thrust direction opposite to said field
magnets, said rotor including an armature core divided into at least three
block cores equally spaced apart from one another,
each of said block cores including teeth and armature coils wound in the
form of a concentrated winding around said teeth with the phases of said
armature coils being shifted by an electrical angle corresponding to the
distance between said block cores.
25. A linear motor as set forth in claim 24, wherein said at least three
block cores comprise a first block core, a second block core, and a third
block core, each of said first, second and third block cores having nine
teeth and a length equivalent to eight times the pitch of said field
magnets, said teeth being arranged at equal pitches and being grouped by
threes, the distance between said first, second and third block cores
being equivalent to two-thirds of the pitch of said field magnets, said
armature coils of said first block core being wound in the order of U
phase, V phase and W phase in respective groups thereof, said armature
coils of said second block core being wound in the order of V phase, W
phase and U phase in respective groups thereof, said armature coils of
said third block core being wound in the order of W phase, U phase and V
phase in respective groups thereof.
26. A linear motor as set forth in claim 24, wherein said at least three
block cores comprise a first block core, a second block core, and a third
block core, each of said first, second and third block cores having nine
teeth and a length equivalent to eight times the pitch of said field
magnets, said teeth being arranged at equal pitches and being grouped by
threes, the distance between said first, second and third block cores
being equivalent to one-third of the pitch of said field magnets, said
armature coils of said first block core being wound in the order of U
phase, V phase and W phase in respective groups thereof, said armature
coils of said second block core being wound in the order of W phase, U
phase and V phase in respective groups thereof with the winding direction
reversed from the winding direction of said armature coils of said first
block core, said armature coils of said third block core being wound in
the order of V phase, W phase and U phase in respective groups thereof in
the same winding direction as that of said first block core.
27. A linear motor as set forth in claim 24, wherein said at least three
block cores comprise a first block core having nine teeth and a length
equivalent to eight times the pitch of said field magnets, said teeth of
said first block core being arranged at equal pitches, a second block core
having eighteen teeth and a length equivalent to sixteen times the pitch
of said field magnets, said teeth of said second block core being arranged
at equal pitches, and a third block core similar to said first block core,
the distance between said first, second and third block cores being
equivalent to two-thirds of the pitch of said field magnets, said teeth in
said first, second and third block cores being grouped three by three,
said armature coils of said first block core being wound in the order of U
phase, V phase and W phase in respective groups thereof, said armature
coils of said second block core being wound repeatedly two times in the
order of W phase, V phase and U phase in respective groups thereof, said
armature coils of said third block core being wound in the order of V
phase, U phase and W phase in respective groups thereof.
28. A linear motor as set forth in claim 24, wherein said at least three
block cores comprise a first block core, a second block core and a third
block core spaced apart from one another by a distance equivalent to
one-third of the pitch of said field magnets, said teeth of said first,
second and third block cores being grouped by threes, said armature coils
of said first block core being wound in the order of U phase, V phase and
W phase in respective groups, said armature coils of said second block
core being wound in the order of W phase, U phase and V phase repeatedly
two times in respective groups with the winding direction reversed, said
armature coils of said third block core being wound in the order of V
phase, W phase and U phase in the same winding direction as that of the
first block core.
29. A linear motor as set forth in claim 24, wherein said at least three
block cores comprise a first block core, a second block core and a third
block core spaced apart from one another by a distance equivalent to
one-third of the pitch of said field magnets, said teeth of said first,
second and third block cores being grouped by threes, said armature coils
of said first block core being wound in the order of U phase, V phase and
W phase in respective groups, said armature coils of said second block
core being wound in the order of V phase, U phase and W phase repeatedly
two times in respective groups with the winding direction reversed, said
armature coils of said third block core being wound in the order of W
phase, V phase and U phase in the same winding direction as that of said
first block core.
30. A linear motor as set forth in claim 24, further comprising a spacer
made of a non-magnetic substance arranged between adjacent ones of said at
least three block cores.
31. A linear motor as set forth in claim 24, further comprising a
temperature sensor arranged between adjacent ones of said at least three
block cores to detect the temperature of an intermediate portion of said
armature coils alongside said temperature sensor.
32. A linear motor as set forth in claim 24, wherein said temperature
sensor is arranged in a resin-molded armature.
33. A linear motor as set forth in claim 24, wherein said teeth of said
block cores each have an iron relay portion for coupling said teeth
together, said iron relay portion including an engagement projection
formed at one side of said tooth and a fitting portion formed at the other
side of said tooth to be engaged with said engagement projection, said
teeth being coupled together by engaging said engagement portion of one of
said teeth with said fitting portion of another of said teeth.
34. A linear motor as set forth in claim 24, further comprising a fixing
portion, said field magnets being attached to said fixing portion.
35. A linear motor as set forth in claim 24, wherein the distance between
said at least three block cores is determined by dividing the electrical
angle of the pitch of said field magnets by the number of block cores and
multiplying the result by an integer less than the number of block cores.
36. A linear motor as set forth in claim 35, wherein said at least three
block cores consists of three block cores and the electrical angle of the
pitch of said field magnets is 180 degrees such that the distance between
said three block cores is 60 degrees which translates into 1/3 of the
pitch of said field magnets or 120 degrees which translates into 2/3 of
the pitch of said field magnets.
37. A linear motor as set forth in claim 24, wherein a thrust direction is
defined as a direction of movement of said rotor relative to said field
magnets, said at least three block cores being arranged linearly in the
thrust direction.
38. A method for constructing a linear motor, comprising the steps of:
spacing field magnets at equal intervals from one another with the field
magnets having an equal pitch;
arranging a rotor having an armature core opposite the field magnets;
dividing the armature core into at least three block cores, each block core
including teeth and armature coils wound in the form of a concentrated
winding around the teeth;
determining a distance between the block cores by dividing the electrical
angle of the pitch of the field magnets by the number of block cores and
multiplying the result by an integer less than the number of block cores;
and
spacing the block cores equidistant from one another by the determined
distance. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates to a moving-coil linear motor.
A prior art moving-coil linear motor is, as shown in FIG. 22, provided with
a field permanent magnet 11 secured at a fixing portion and a comb
teeth-like armature core 12 opposed to the field permanent magnet 11. The
comb teeth-like armature core 12 has armature coils 13 divided and wound
therein. In the armature core 12 having the wound armature coils 13, where
the number of phases is n, the number of field permanent magnets 11 is p,
and the number of teeth 14 corresponding to one pole is q, the number N of
teeth provided in the armature core 12 is:
N=n.times.p.times.q
In the armature coil 12 which has a number of teeth formed equidistantly,
three-phase windings U, V, and W of the armature coil 13 are wound with at
least two tooth pitches skipped.
Therefore, the moving-coil linear motor is such that the magnetic circuit
of a moving armature core 12 is not endless and is open at both ends
thereof, whereby slots at both sides in the rotor thrust direction
accommodate one coil, differing from the slots at the central portion.
And, an edge effect occurs due to the slots, wherein a cogging thrust TC
of one cycle is generated in the magnetic pole pitch of field magnets 11,
thereby causing unevenness in the thrust.
SUMMARY OF THE INVENTION
Also, where a temperature sensor is inserted into a slot accommodating a
coil in order to control the temperature of the coils, it is necessary to
make the slot large, whereby the armature core is increased in size, and
such a problem occurs, by which the ratio of occupancy of windings is
lowered. Therefore, although the temperature sensor is provided at both
ends of the coils in the linear motors, the temperature of the central
portion of the coil cannot be measured, wherein only inaccurate
temperature detection was possible.
DISCLOSURE OF THE INVENTION
The present invention solves such problems resulting from the cogging
thrust, and it is therefore an object of the invention to provide a linear
motor in which the detection accuracy of the coil temperature can be
improved.
Therefore, in the invention, the armature core is divided into a plurality
of block cores, and teeth secured at the respective block cores
equidistantly from one another are provided with armature coils wound in
the form of lumped winding, and the block cores are disposed in the thrust
direction where spacing corresponding to an electrical angle greater by an
integer number of times than a value which is obtained by dividing the
electrical angle 180.degree. of the magnet pitch by the number of
divisions is secured between the block cores, wherein the armature coils
of the block cores between which the spacing is secured are wound so that
their phases shift by the electrical angle corresponding to the spacing.
Therefore, phases of the cogging thrust generated due to the armature coils
of the respective block cores are subjected to phase shifts at the
electrical angle in response to the spacing one after another, whereby the
cogging thrusts generated in the respective block cores can be mutually
counterbalanced and are zeroed by each other. Therefore, the winding can
be constituted by a complete three-phase balanced winding, and it is
possible to insert a temperature sensor in the spacing between the block
cores.
The armature core is divided into three block cores, that is, the armature
core is provided with the first block core, second block core, and third
block core, each of which has nine teeth having a length longer by eight
times than the magnet pitch at equal intervals, and is provided with a
three-phase armature coil wound in the form of lumped winding with the
teeth of the respective block cores divided into three groups, a spacing
equivalent to two-thirds the magnet pitch is provided between the
respective block cores, and is disposed in the thrust direction, wherein
the first block core is divided into three groups to form U, V and W
phases in that order, in which an armature coil is wound, the second block
core is divided into three groups to form V, W and U phases in the order,
in which an armature coil is wound, and the third block core is divided
into three groups to form W, U and V phases in that order, in which an
armature coil is wound, whereby the respective phase coils are connected
in equilibrium to each other.
The three block cores are disposed in the thrust direction with a spacing
of one-third the magnet pitch secured between the three block cores, and
teeth are divided into three groups, wherein an armature coil may be wound
in the respective groups in the order of U, V and W phases in the first
block core, an armature coil maybe wound, with the winding direction
reversed, in the respective groups in the order of W, U and V phases in
the second block core, and an armature coil may be wound, in the same
direction as that in the first block core, in the order of V, W and
U-phases in the third block core.
Also, the armature core is divided into two block cores, wherein the first
block core is provided with nine teeth, longer by eight times than the
magnet pitch, at equal intervals, the second block core of the same
configuration as that of the first block core is disposed in the thrust
direction with a spacing of one half the magnet pitch secured between the
block cores, and teeth of the first block core are divided into three
groups and an armature coil is wound in the order of U, V, and W phases,
wherein in the second block core, the V-phase coil is wound in one tooth,
the W-phase coil is wound in the next three teeth as a group, the U phase
coil is wound in the further next three teeth as a group, and the V-phase
coil is wound in the remaining two teeth.
Further, as a means to bring about similar effects, there is a means in
which the second block core is divided into three groups, and an armature
coil is wound in the order of V phase and W phase so that the phase of the
magnetomotive force vector is electrically shifted by 120.degree. from
that of the first block core.
Also, in any case, a spacing piece of a magnetic substance is inserted in
the clearance between the block cores to retain the spacing, and a
temperature sensor such as a thermister or a thermal protector is inserted
into the clearance, and it is possible to control the temperature of the
coils.
Thus, according to the invention, in a moving coil linear motor, the
armature core of the rotor is divided into a plurality of block cores
which will be disposed in the thrust direction, the respective block cores
are provided with teeth divided into groups equivalent to the number of
phases disposed at equal intervals, and the block cores are disposed in
the thrust direction in a state where they are placed in the thrust
direction with a spacing greater by an integer number of times by which
the magnet pitch is divided by the number of divisions between the block
cores. Since the phase of the armature coil of the respective core is
caused to shift by an electrical angle corresponding to the abovementioned
spacing, the armature coil can be wound in the form of lumped winding on
the teeth, and the cogging thrust resulting from the edge effect of the
rotor can be counterbalanced to zero the cogging thrust, whereby it is
possible to obtain a highly accurate linear motor.
The rotor is divided into three block cores, which are disposed in the
thrust direction at a spacing equivalent to two-thirds or one-third of the
magnet pitch, the respective block cores are caused to have nine teeth
longer by eight times than the magnet pitch, and they are divided into
three groups to form a winding, wherein a coil is directly wound on the
teeth in the form of lumped winding, and the flux linkage is large.
Further, 3-phase balanced connection can be secured.
Also, the rotor may be divided into two block cores, which may be disposed
at intervals equivalent to one half of the magnet pitch, and the
respective armature coils are caused to differ in phase by 90.degree. from
each other, and where the cogging thrusts of the same phase are connected
to each other in series, the circulating current resulting from the phase
difference in the magnetomotive force can be removed, and it is possible
to obtain a highly efficient linear motor. The armature coil of the
respective block core is caused to shift by an electrical angle
corresponding to the spacing, whereby it is possible to directly wind the
armature coil on the teeth in the form of lumped winding, and there is an
effect by which the cogging thrust resulting from the edge effects of the
rotor can be zeroed by mutually counterbalancing the same in the
respective block cores. Therefore, a highly accurate linear motor can be
obtained.
The rotor is divided into three block cores which will be disposed in the
thrust direction at a spacing equivalent to two-thirds or one-third of the
magnet pitch, and nine teeth are provided, with a length longer by eight
times than the magnet pitch, which are divided into three groups and are,
respectively, provided with winding, whereby, since the winding is wound
directly on the teeth to secure a lumped winding, the flux linkage is
increased, and three-phase balanced connection can be obtained.
Also, the rotor is divided into two block cores which are disposed at
intervals equivalent to one half of the magnet pitch. Where the respective
armature coils are connected with the same phase cogging thrusts placed in
series in a state where the respective armature coils are placed with a
difference of 90.degree. in phase, a circulating current resulting from a
difference in the electromotive force is removed, and a highly efficient
linear motor can be obtained.
Further, it is possible to detect the temperature of the intermediate coil
portions by providing a temperature sensor in the clearance, whereby it is
possible to accurately control the temperature of the coils in a linear
motor. Also, if the clearance incorporating the temperature sensor is
integrated by resin molding, and retaining of the temperature sensor
becomes reliable, wherein an advantage can be obtained by which the
detection accuracy of the temperature can be improved.
Also, by engaging and connecting the teeth, which constitute the block
cores, with engagement projections and fitting portions of an iron relay
part, the teeth can be easily punched out, whereby the teeth on which
coils are wound can be linked with each other, and it becomes easy to
carry out the winding work.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side sectional view showing a first embodiment of the
invention,
FIG. 2 is an explanatory view of winding in the first embodiment, wherein
(a) is a connection diagram, and (b) is a winding layout diagram,
FIG. 3 is a characteristic view showing states of the cogging thrust in the
first embodiment,
FIG. 4 is a side sectional view showing a second embodiment,
FIG. 5 is an explanatory view of winding in the second embodiment, wherein
(a) is a connection diagram, and (b) is a winding layout diagram,
FIG. 6 is a characteristic view showing states of the cogging thrust in the
second embodiment,
FIG. 7 is a side sectional view showing a third embodiment,
FIG. 8 is an explanatory view of winding in the third embodiment, wherein
(a) is a connection diagram, and (b) is a winding layout diagram,
FIG. 9 is a characteristic view showing states of the cogging/thrust in the
third embodiment,
FIG. 10 is a vector diagram of respective phases in the third embodiment,
FIG. 11 is an explanatory view of winding, which shows a modified version
of the fourth embodiment, wherein (a) is a connection diagram, and (b) is
a winding layout diagram,
FIG. 12 is a side sectional viewshowing a fifth embodiment,
FIG. 13 is an explanatory view of winding in the fifth embodiment, wherein
(a) is a connection diagram, and (b) is a winding layout diagram,
FIG. 14 is a side sectional view of a sixth embodiment,
FIG. 15 is an explanatory view of winding in the sixth embodiment, wherein
(a) is a connection diagram, and (b) is a winding layout diagram,
FIG. 16 is a side sectional view showing a seventh embodiment,
FIG. 17 is another side sectional view showing the seventh embodiment,
FIG. 18 is a winding layout diagram in the seventh embodiment,
FIG. 19 is a winding layout diagram in the seventh embodiment,
FIG. 20 is a front elevational view showing an eighth embodiment,
FIG. 21 is a partially side sectional view showing an ninth embodiment,
FIG. 22 is a side sectional view showing a prior art example, and is a
characteristic view showing the state of the cogging thrust.
DETAILED DESCRIPTION
A description is given of the embodiments of the invention with reference
to the accompanying drawings.
FIG. 1 shows the first embodiment of the invention. 1 indicates field
magnets attached to the fixing portion 2 at equal pitches Pm, and the
field magnets 1 are disposed at a length which is obtained by adding the
length of the rotor 3 moving with respect to the field magnets 1 to a
stroke for which the rotor moves. The cores attached to the rotor 3 is
divided into three cores, the first block core 31, second block core 32,
and third block core 33, which are provided in the moving direction.
The respective block cores 31, 32, and 33 are provided with a length
equivalent to eight times the pitch Pm of the field magnets 1 and are,
respectively, provided with nine teeth 4 at equal pitches Pt, wherein the
teeth 4 are divided into three groups, and armature coils 5 of the
respective phases are directly wound in the form of lumped winding. 6 is a
spacer placed between the respective block cores, and has a width
equivalent to two thirds of the pitch Pm of the field magnet 1. It is
highly recommended that the spacer is made of a non-magnetic body.
A slot pitch in the winding layout of an electromagnetic structure where
the number of magnetic poles corresponding to the three-phase nine coils
becomes eight therewith becomes 160.degree. in terms of electrical angle.
Therefore, since the coil skips as in No. 1 and No. 2, coils are directly
wound on the teeth in the form of lumped winding. Accordingly, as shown in
the connection diagram in FIG. 2(a), the first block core 31 is provided
with coils 5 in the teeth 4 of the respective groups in the order of U
phase, V phase and W phase.
The second block core 32 is caused to shift in the thrust direction with
respect to the first block core 31 by the spacer 6 by two thirds the
magnet pitch Pm, and since the magnet pitch Pm is 180.degree. in terms of
electrical angle, the second block core will shift by 120.degree. in terms
of electrical angle, wherein since the armature coil of the block core is
given a phase shift of 120.degree. with respect to the armature coil of
the first block core, the second block core is provided with armature
coils 5 in the order of V phase, W phase and U phase from the edge at the
same side as in the first block core.
Also, armature coils 5 of the third block core 33 is caused to shift by
120.degree. from the second block core 32 as well, wherein the third block
core 33 is wound in the order of W phase, U phase and V phase.
Accordingly, as in a case where no phase shifts, the flux linkage becomes
the maximum at the position where the respective phase coils are opposed
to the corresponding magnets.
Thus, the coil layout of the respective block cores of the rotor 3 is as
shown in FIG. 2(b), and the block cores 31, 32 and 33 are spaced from each
other by spacers 6 having a space equivalent to two-thirds (120.degree. in
terms of electrical angle) of the pitch Pm of the field magnet 1.
Accordingly, if the armature coils of the respective block cores are wound
with a difference in phase, which is 120.degree. in terms of electrical
angle, cogging thrusts TC1, TC2 and TC2 generated due to an edge effect of
the respective block cores produces, as shown in FIG. 3, a difference in
phase which is 120.degree., thereby zeroing the sum thereof.
FIG. 4 is a side sectional view showing the second embodiment, wherein
parts which are identical to those in the first embodiment are given the
same reference numbers. The core of the rotor 3 is divided into three
block cores, and they are linked to and coupled to each other with a
spacer 6a having a width equivalent to one-third times the pitch Pm of the
field magnet 1, and the respective block cores 31, 32 and 33 have a length
equivalent to eight times the pitch Pm of the field magnet 1, each of
which has nine teeth at equal pitches Pt, and the nine teeth are divided
into three groups.
Thus, the teeth position of the same side edge of the respective block
cores shifts by one-third of the magnet pitch Pm, placing a spacer 6a
between the respective block cores, wherein since the magnet pitch Pm is
180.degree. in terms of electrical angle, the shift becomes 60.degree. in
terms of electrical angle.
Therefore, as shown in the connection diagram in FIG. 5(a), in the first
block core 31, coils of U phase, V phase and W phase are directly wound in
slots of the respective groups in the order from the edge, as regards the
armature coil of the second block core 32, coils are wound with the
winding direction reversed, in the order of W phase, U phase and V phase
because the phase is caused to shift by 60.degree. in terms of electrical
angle, and in the third block core 33, in order to secure a difference in
phase of 60.degree. from that of the second block core, the winding
direction of the third block core is made the same as that of the first
block core, and coils are wound in the order of V phase, W phase and U
phase. The winding arrangement of the block cores in this state is
illustrated in FIG. 5(b).
Accordingly, the cogging thrusts TC1, TC2, and TC3 arising by the edge
effects of the respective block cores causes a difference in phase of
60.degree. as shown in FIG. 6, thereby zeroing the sum thereof.
FIG. 7 is a side sectional view showing the third embodiment, wherein 1 is
a field magnet, 2 is a fixing portion, and 3 is a rotor. In the
embodiment, two block cores 31 and 32 provided with nine teeth with a
length equivalent to eight magnet pitches Pm of the field magnet 1 at
equal intervals are provided in a state where a spacer 6b having a width
equivalent to one half of the magnet pitch Pm is placed therebetween.
As shown in FIG. 8(a), in the first block core 31, nine teeth 4 are divided
into three groups to form U phase, V phase and W phase in the other by
winding armature coils 5. In the second block core 32, one coil of V phase
is wound on the first one tooth, a coil of W phase is wound on the second
three teeth, a coil of U phase is wound on the third three teeth, and two
coils of V phase are wound on the next two teeth, whereby armature coils 5
of the respective block cores are wound in the form of three-phase
balanced winding with 90.degree. as a difference in phase, and the flux
linkage can be maximized.
Therefore, the winding layout of the respective block cores 32 and 33
becomes as in FIG. (b). As shown in FIG. 9, the cogging thrusts TC1 and
TC2 arising due to the edge effects of the first block core 31 and second
block cores 32 can be mutually counterbalanced.
Also, by connecting the armature coil of the first block core to the
armature coil of the second block core in the same phase in series, the
phases of electromotive force vectors arising in the two armatures are
synthesized as shown in FIG. 10, wherein the circulating current can be
removed.
FIG. 11 is a winding layout diagram showing the fourth embodiment, which
illustrates a modified version of the coil layout and coil connecting
method shown in FIG. 8.
As shown in FIG. 11(a), in the first block core 31, nine teeth 4 are
divided into three groups to form U phase, V phase and W phase in the
order by winding armature coils 5. In the second block core 32, nine teeth
are divided into three groups to form V phase, and W phase, U phase in
that order by winding armature coils as well, whereby the armature coils 5
of the respective block cores can be wound in the form of three-phase
balanced winding with 90.degree. secured as a difference in phase.
Therefore, the winding layout of the respective block cores 31 and 32
becomes as shown in FIG. 11(b). The cogging thrusts TC1 and TC2 arising
due to the edge effects the first block core 31 and second block core 32
can be counterbalanced as shown in FIG. 9. Also, by connecting the
armature coil of the first block core 31 to the armature coil of the
second block core in the same phase in series, the phases of electromotive
force vectors arising in the two armatures are synthesized as shown in
FIG. 10, whereby the circulating current can be removed.
FIG. 12 shows the fifth embodiment of the invention, which is a preferable
example where it is necessary to lengthen a linear motor.
In the same drawing, 1 is a field magnet attached to the fixing portion 2
at equal intervals. The field magnets 1 are disposed so as to cover a
length which is obtained by adding the length of a rotor 3 moving opposed
to the field magnets 1 to a stroke along which the rotor 3 moves. Cores
secured in the rotor 3 are divided into the first block core 31, second
block core 32 and block core 33 and disposed in the moving direction.
The respective block cores 31 and 33 have a length equivalent to eight
times the pitch Pm of the field magnet 1 and are provided with nine teeth
4 at equal intervals. The teeth 4 are divided into three groups, and
armature coils 5 of the respective phases are directly wound in the form
of lumped winding in the respective groups. The block core 32 has a length
equivalent to two times (sixteen times the pitch Pm) the block core 31 or
33 and are provided with eighteen teeth 4 at equal pitches Pt. The teeth 4
are, respectively, divided into three groups, wherein armature coils 5 of
the respective phases are directly wound in the form of lumped winding in
the respective groups.
6 is a spacer inserted between the respective block cores, and has a width
equivalent to two-thirds of the pitch Pm of the field magnet 1. It is
highly recommended that the spacer is made of a non-magnetic body.
The slot pitch in the winding layout of an electromagnetic structure in
which the number of magnetic poles with respect to three-phase nine coils
becomes eight becomes 160.degree. in terms of electrical angle, and the
coils skip as in No. 1 and No. 2. Therefore, coils can be directly wound
on the teeth, and lumped winding can be secured. Therefore, as shown in
the connection diagram in FIG. 13(a), the first block core 31 will have
coils 5 in the order of U phase, V phase and W phase in the teeth of the
respective groups.
The second block core 32 is caused to shift by spacers 6 by two-thirds of
the field magnet pitch Pm in the thrust direction with respect to the
first block core 31, wherein the magnet pitch Pm is 180.degree. in terms
of electrical angle. Therefore, the second block core 32 will shift by
120.degree. in terms of electrical angle. Since the armature coil of the
block core is caused to have 120.degree. as a difference in phase with
respect to the armature coil of the first block core 31, the armature coil
5 will form a V phase, W phase, and U phase in that order from the edge of
the same side as that of the first block core twice repeatedly.
Also, the armature coil 5 of the third block core 33 is caused to shi | | |
