Linear motor having dual coil configuration
A linear motor is provided that includes a magnetic assembly, a movable element and a coil assembly that is operative to interact with the magnetic assembly to drive the movable element along a direction. The coil assembly further includes a first coil section having a first motor force constant and a second coil section having a second motor force constant that is lower than that of the first coil section for driving the movable element along the said direction.
1. A linear motor comprising:
a magnetic assembly;
a coil bracket;
a coil assembly mounted onto the coil bracket, the coil assembly being operative to interact with the magnetic assembly to drive the coil bracket along a direction; wherein the coil assembly comprises a first coil section having a first motor force constant and a second coil section having a second motor force constant that is lower than the first motor force constant of the first coil section, the first and second coil sections being positioned within the coil bracket and configured to drive the coil bracket along the direction.
2. The linear motor as claimed in claim 1 , wherein the first and second coil sections each comprises a plurality of multi-phase coils.
3. The linear motor as claimed in claim 2 , wherein a number of phases in the first coil section is the same as a number of phases in the second coil section.
4. The linear motor as claimed in claim 2 , wherein a number of coils per phase is different for each of the first and second coil sections.
5. The linear motor as claimed in claim 2 , wherein there is an equal number of coils per phase in the first coil section.
6. The linear motor as claimed in claim 1 , wherein coils of the first coil section are juxtaposed alongside coils of the second coil section substantially along the same plane.
7. The linear motor as claimed in claim 6 , wherein the coils of the second coil section are distributed consecutively between the coils of the first coil section.
8. A gantry system having first and second linear motors for driving a gantry beam along a direction, at least one of the linear motors comprising:
a magnetic assembly;
a coil bracket; and
a coil assembly mounted onto the coil bracket, the coil assembly being operative to interact with the magnetic assembly to drive the coil bracket along the direction, the coil assembly comprising a first coil section having a first motor force constant, the coil assembly further comprising a second coil section having a second motor force constant that is lower than the first motor force constant of the first coil section, the first and second coil sections being positioned within the coil bracket and configured to drive the coil bracket along the direction.
9. The gantry system as claimed in claim 8 , wherein the second linear motor is configured to cooperate with the first linear motor to drive the gantry beam in a linear direction, and the second linear motor is also configured for relative motion with respect to the first linear motor in the linear direction so as to rotate the gantry beam.
10. The gantry system as claimed in claim 8 , wherein the first coil section of the at least one linear motor is operative to substantially drive linear motion of the gantry beam and the second coil section of the at least one linear motor is operative to substantially drive rotary motion of the gantry beam.
11. The gantry system as claimed in claim 10 , wherein the at least one linear motor is constructed to achieve a ratio of moving mass/motor force constant in a linear axis that is similar to a ratio of moving inertia/torque constant in a rotational axis.