Electromagnetic actuator with linear control
AssigneeNational Space Development Agency of Japan
InventorTetsuji Narasaki
Life of this patent
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Abstract
An electromagnetic actuator includes a cylindrical rod made of a magnetic substance and having a large number of annular teeth formed on an outer surface thereof at a fixed pitch, and a plurality of annular electromagnets fitted on the cylinder rod. The intervals of the annular electromagnets are set such that the offsets between the annular teeth of the annular electromagnets and the annular teeth of the corresponding cylindrical rod gradually increase. This ensures highly accurate axisymmetric configuration which in turn ensures a completely axisymmetric distribution of the magnetic flux. In consequence, the radial force which acts between the electromagnet and the rod can be reduced, and control over the movement of the rod in the axial direction is thus facilitated.
Claims15
An electromagnetic actuator comprising:
- a cylindrical rod made of a magnetic substance and having a large number of annular teeth formed on an outer surface thereof at a fixed pitch;
- and
- a plurality of annular electromagnets fitted on said cylindrical rod, each of said annular electromagnets having a hollow annular electromagnet core whose inner peripheral intermediate portion is removed and two annular walls are formed on both sides of said inner peripheral intermediate portions, and loosely fit on said cylindrical rod, a large number of annular teeth provided on said annular walls of said hollow annular electromagnet core by the same pitch as that of the annular teeth of said cylindrical rod, and an energizing coil wound along a circumference within said hollow annular electromagnet core, said annular electromagnets being disposed at intervals which ensure that offsets between the annular teeth of said annular electromagnets and said annular teeth of said cylindrical rod gradually increase, said cylindrical rod being driven in an axial direction thereof by energization and de-energization of said electromagnets.
An electromagnetic actuator comprising:
- a cylindrical rod made of a magnetic substance, said cylindrical rod having a large number of annular teeth which are formed on an outer surface thereof at a fixed pitch and a plurality of helical grooves which extend in an axial direction of said rod across said annular teeth on the outer surface of said rod and which are formed at a fixed interval on a circumference of said rod;
- a plurality of annular electromagnets fitted on said cylindrical rod;
- and
- a restricting electromagnet fitted on said cylindrical rod and coupled to said plurality of annular electromagnets, said restricting electromagnet restricting movement of said cylindrical rod in the axial direction thereof, each of said annular electromagnets having a hollow annular electromagnet core whose inner peripheral intermediate portion is removed and two annular walls are formed on both sides of said inner peripheral intermediate portion, and loosely fit on said cylindrical rod, a large number of annular teeth provided on said annular walls of said hollow annular electromagnet core by the same pitch as that of the annular teeth of said cylindrical rod, helical grooves on said annular walls of said hollow annular electromagnet core which extend in the axial direction across said annular teeth and which are disposed at a fixed interval on the circumference of said annular walls and at an inclination angle different from that of said helical grooves of said cylindrical rod, said inclination angle being the ratio of a circumferential component to an axial component of said helical groove, and an exciting coil along the circumference would within said core, said annular electromagnets being disposed at intervals which ensure that offsets between the annular teeth of said annular electromagnets and said annular teeth of said cylindrical rod gradually increase, said cylindrical rod being rotated about its own axis in a state wherein the movement of said cylindrical rod int he axial direction is suspended and being driven in the axial direction thereof in a state wherein rotation of said cylindrical rod about is own axis is suspended.
Dependencies are inferred from the claim text.