Screw driving apparatus having magnet nut

Claim 2

A driving apparatus for producing a linear movement between an actuated means and a stator means comprising: a stator means; an actuated means; a drive screw mounted on one of said actuated means and stator means being continuously formed with equally spaced threads; at least one nut means mounted on the other of said actuated means and stator means being formed to provide at least two pole pieces; winding means magnetically associated with said pole pieces; each of said pole pieces having an inner diameter pole surface formed with equally spaced threads the same as the threads of said screw; restricting means comprising at least two of said pole pieces for effecting a stationary restriction of said actuated means, said restricting means includes a fraction of the thread pitch of said actuated means; and drive means for rotating said drive screw.

Claim 3

A driving apparatus as defined in claim 1, comprising; detector means generating a control signal proportional to the displacement of said actuated means and mounted on said nut; and control means electrically connected to said detector means for compensating the displacement of said actuated means and being controlled by said control signal.

Claim 4

A threaded driving mechanism for producing linear movement of one threaded part with respect to another threaded part, comprising: a linearly moveable support; a continuously threaded drive screw suitably journaled for rotation in said linearly moveable support, said drive screw being formed of a magnetic material; a stator nut having at least two pole pieces axially spaced along said drive screw and being threaded for non-engagingly receiving said drive screw; at least one exciting coil disposed between said at least two pole pieces; means for energizing said at least one exciting coil; and means for rotating said drive screw to cause said linearly movable support to move linearly with respect to said stator nut.

Claim 5

A threaded driving mechanism for producing linear movement of one threaded part with respect to another threaded part, comprising: a linearly moveable support; a continuously threaded drive screw suitably journaled for rotation in said linearly moveable support, said drive screw being formed of a magnetic material; a stator nut having at least two pole pieces axially spaced along said drive screw and being threaded for non-engagingly receiving said drive screw; at least one exciting coil disposed between said at least two pole pieces; means for energizing said at least one exciting coil; and means for rotating said drive screw to cause said linearly movable support to move linearly with respect to said stator nut.

Claim 6

A threaded driving mechanism according to claim 3, further comprising spacer means for supportingly spacing said at least two pole pieces, said spacer means being formed of a magnetic material.

Claim 7

A threaded driving mechanism according to claim 3, wherein said at least two pole pieces are substantially tubular in configuration the threaded inside diameter of which is larger than the threaded outside diameter of said drive screw.

Claim 8

A threaded driving mechanism according to claim 3, wherein said threads of said drive screw and said at least two pole pieces are square-type threads, and said threads of said drive screw are so displaced axially of said threads of said pole pieces that the magnetic flux lines produced in the gaps therebetween are inclined toward the center of said stator nut.

Claim 9

A threaded driving mechanism according to claim 3, wherein said stator nut is composed of three pole pieces axially spaced along said drive screw, and each adjacent pair of said three pole pieces has a set of three coils radially arranged between about said drive screw.

Claim 10

A threaded driving mechanism according to claim 7, further comprising: power means for energizing the radially inside coils of each set of three radially arranged coils for magnetizing the outside pole pieces of said three pole pieces N and the inside pole pieces of said three pole pieces S; detector means for detecting inductance changes being connected to the middle exciting coil of each set of three radially arranged coils; and control means connected to the radially outside coils of each set of three radially arranged exciting coils and to said detector means for controlling the position of said linearly movable support.

Claim 11

A threaded driving mechanism according to claim 3, wherein said stator nut is composed of two nut portions, one of said two nut portions having three axially spaced pole pieces with each adjacent pair of said three pole pieces having a set of two coils radially arranged therebetween about said drive screw, the other of said two nut portions having three axially spaced pole pieces with each adjacent pair of said three pole pieces having an exciting coil disposed therebetween and about said drive screw; magnetic insulative means for supporting said nut portions in fixed axially spaced relation; detector means connected to the coils in the other of said nut portions for detecting inductance changes caused by inertial displacement; and control means connected to the coils of said one of said nut portions and to said detector means for controlling the position of said linearly movable support.

Claim 12

A threaded driving mechanism according to claim 9, wherein said nut portions are substantially semi-cylindrical in configuration.

Claim 13

A threaded driving mechanism according to claim 7, wherein the threads of the outer pole pieces of said three axially spaced pole pieces are displaced axially of the threads of said drive screw such that the magnetic flux lines produced in the gaps therebetween are inclined toward the center of said stator nut, and the threads of the central pole piece of said three axially spaced pole pieces directly oppose the threads of said drive screw.

Claim 14

A threaded driving mechanism according to claim 3, wherein said stator nut is composed of three pole pieces axially spaced along said drive screw with each adjacent pair of said three pole pieces having a set of two coils radially arranged therebetween about said drive screw, and a pair of capacitance detecting nut means are respectively secured to opposite sides of the stator nut being insulatively spaced therefrom for detecting the capacitance between said nut means and said drive screw, whereby such capacitance may be conducted to control means for controlling the movement of said linearly movable support means.