Cylinder-Type Linear Motor and Moving Part Thereof

Abstract

There is provided a cylinder-type linear motor capable of shortening the total motor length with respect to a predetermined stroke length S and capable of being operated without sensor means for sensing the position of a moving part being added in the axial direction. The cylinder-type linear motor includes a fixed part 20 having a coil assembly 28 formed by a plurality of (n number of) ring-shaped coils 22 . . . 27 arranged in the axial direction and a yoke member 21 made of a magnetic material, and a moving part 10 having a linear motion shaft 11 provided on the axis line of the fixed part 20 and a permanent magnet assembly 15 having one or more permanent magnets magnetized in the axial direction. A stroke S is equal to or smaller than (n×C−M), the axial length Y of the yoke member is set equal to or larger than (M+S+0.8×D), and the ring-shaped coils 22 . . . 27 are arranged in a predetermined phase order and the ring-shaped coils of the same phase are connected to each other to form one phase winding. Also, there is provided a moving part of a cylinder-type linear motor, which can improve the magnetic flux density distribution waveform near both end portions of the moving part assembly and can improve the thrust characteristic by bringing the magnetic flux density distribution waveform closer to a cosine waveform and by increasing the amplitude of cosine waveform. In this moving part, a permanent magnet assembly 5 has a pair of permanent magnets 2 and 4 magnetized in the axial direction, which are arranged so that the end faces with the same polarity face to each other; a pair of ring-shaped fixing members 6 and 7 each having an outside diameter smaller than the outside diameters of the paired permanent magnets 2 and 4, which are fixed on the linear motion shaft 11 so as to be in contact with both sides of the paired permanent magnets 2 and 4; and a pair of ring-shaped permanent magnets 8 and 9 magnetized in the radial direction so that the polarity on the outer peripheral surface is different from the polarity on the opposed end faces of the paired permanent magnets 2 and 4, which are provided on the outer peripheral surfaces of the paired ring-shaped fixing members 6 and 7.

Dependencies are inferred from the claim text.