1. An alignment apparatus which generates a driving force between a movable element and a stator facing the movable element to align the movable element, said apparatus comprising:
magnet units which are two-dimensionally formed on the movable element and comprise a plurality of permanent magnets arrayed in accordance with an array cycle; and
poly-phase coils which are formed on the stator and are arrayed at intervals corresponding to the array cycle,
wherein said poly-phase coils comprise first coils which have linear portions extended in a first direction,
each length of the linear portions of the first coils is longer than each length of the magnet units in the first direction, and
the number of permanent magnets facing each of the linear portions of coils having the same phase among the first coils is equal in each of said magnet units.
2. The apparatus according to claim 1, wherein the first coils are arrayed in a second direction perpendicular to the first direction.
3. The apparatus according to claim 1, wherein said poly-phase coils comprise second coils which have linear portions extended in a second direction perpendicular to the first direction,
each length of the linear portions of the second coils being longer than each length of the magnet units in the second direction; and
the number of permanent magnets facing each of the linear portions of coils having the same phase among the second coils being equal in each of said magnet units.
4. The apparatus according to claim 3, wherein the first coils are arrayed in the second direction, and the second coils are arrayed in the first direction.
5. An alignment apparatus which generates a driving force between a movable element and a stator facing the movable element to align the movable element, said apparatus comprising:
magnet units which are two-dimensionally formed on the movable element and comprise a plurality of permanent magnets arrayed in accordance with an array cycle; and
poly-phase coils which are formed on the stator and are arrayed at intervals corresponding to the array cycle,
wherein said poly-phase coils comprise first coils which have linear portions extended in a first direction,
each length of the linear portions of the first coils being longer than the sum of a length of said movable element in the first direction and a movement stroke of said movable element in the first direction, and
the number of permanent magnets facing each of the linear portions of coils having the same phase among the first coils is equal in each of said magnet units.
6. The apparatus according to claim 5, wherein said poly-phase coils comprise second coils which have linear portions extended in a second direction perpendicular to the first direction,
each length of the linear portions of the second coils is longer than the sum of a length of said movable element in the second direction and a movement stroke of said movable element in the second direction, and
the number of permanent magnets facing each of the linear portions of coils having the same phase among the second coils is equal in each of said magnet units.
7. The apparatus according to claim 5, further comprising a controller which supplies currents having phase differences to each phase coil of the first coils and generates a driving force for driving said movable element between said magnet units and said poly-phase coils.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A vehicle towing attachment which is to be inserted into a lower portion of a vehicle to be towed and raises and holds wheels when the vehicle is towed, the attachment comprising:
three prongs for retaining a plate spring having the wheel attached thereon.
2. The vehicle towing attachment according to claim 1, wherein a first prong of the three prongs retains a longitudinal end of the plate spring, and second and third prongs retain sides of the plate spring.
3. The vehicle towing attachment according to claim 2, wherein the attachment is constituted by cementing together a first plate having the first prong formed thereon and a second plate having the second and third prongs formed thereon.