US2987657A

US2987657A - Helical magnetic actuator

Info

Publication number: US2987657A
Authority: US
Publication date: 1961-06-06
Anticipated expiration: 1978-06-06

Description

June 6, 1961 A. J. BUCHTENKIRCH ETAL 2,987,657

HELICAL MAGNETIC ACTUATOR Filed Oct. 6, 1958 3 Sheets-Sheet 1 w Hun-III" PlEi 3 Pl i INVENTORS ARTHUR J. BUCHTENKIRCH BY MALCOLM o. WIDENOR ATTORNEYS June 6, 1961 A. J. BUCHTENKIRCH ET AL 2,987,657

HELICAL MAGNETIC ACTUATOR Filed Oct. 6, 1958 3 Sheets-Sheet 2 INVENTORS ARTHUR J. BUCHTENKIRCH BY MALCOLM D. WIDENOR Wang 613 ATTORNEYS June 6, 1961 Filed Oct. 6, 1958 A. J. BUCHTENKIRCH HAL HELICAL MAGNETIC ACTUATOR 3 Sheets-Sheet 3 x I 28 X Jni i i I as INVENTORS ARTHUR J. BUCHTENKIRCH R BY MALCOLM D WIDENO WWW?) ATTORNEYS United States Patent 2,987,657 HELICAL MAGNETIC ACTUATOR Arthur J. Buchtenkirch, Glen Cove, and Malcolm Widenor, Westbury, N.Y., assignors to North Atlantic Industries, Inc., Westbury, N.Y.

Filed Oct. 6, 1958, Ser. No. 765,467 11 Claims. (Cl. 317-192) This invention relates to a helical rotary magnetic actuator generally of the type described in the application of Arthur-J. Bucktenkirch, Ser. No. 477,979, filed December 28, 1954, now Patent No. 2,872,627 of February 3, 1959.

The objects of the present invention as contrasted with that disclosed in the above mentioned prior application, are first, to provide a rotary magnetic actuator wherein the pole faces and the armature faces are helically shaped, in a screw-like configuration, wherein the armature is free to rotate almost one complete revolution at 360, and wherein there is no interference between the pole faces and armature faces.

Another object is to form a helical rotary magnetic actuator wherein the pole faces and armature faces are helical in configuration to thus utilize the entire faces of both for the production of a turning force or torque, and hence, to supply an outstandingly large torque for a limited input.

Yet a further object is to form helical pole faces and armature faces which provide a minimum of distortion of the magnetic flux lines and eliminate turning and twisting of the flux lines to thus produce a maximum torque, but wherein axial thrusts may be canceled out leaving only forces which produce a turning efiect of the armature, and wherein the pole faces and armature faces are formed in parallelism so that the vector or direction of produced total forces remains unchanged during rotation of the armature, for all elements of torque producing surfaces.

These and other objects and advantages of this invention will become apparent upon reading the following description of which the attached drawings form a part.

With reference to the drawings, in which:

FIG. 1 is an elevation view, partially in cross-section, showing the assembled actuator.

FIG. 2 is a disassembled view, in elevation, of the pole pieces, armature and shaft.

FIG. 3 is a view of the armature, per se, taken in the direction of arrows 33 of FIG. 2.

FIG. 4 is a side view of the armature taken in the direction of arrow 4 of FIG. 3.

FIG. 5 is a side view in cross-section of one of the pole pieces and is taken in the direction of arrow 55 of FIG. 6.

FIG. 6 is a top view of a pole piece taken in the direction of arrow 66 of FIG. 2, and

FIG. 7 is a side view of the pole piece taken in the direction of arrow 7 on FIG. 6.

FIG. 8 is an elevation of a modified armature and FIG. 9 is a side view taken in the direction of arrow 9 of FIG. 8.

FIG. 10 is a schematic view of the pole pieces and armatures shown in a developed or unwrapped state to illustrate the force vectors produced.

FIG. 11 is a schematic view of one increment of the pole pieces and armatures taken as if a cross-section of FIG. 10, to show the relationship between the various pole faces and armature faces.

FIG. 12 is a view similar to FIG. 2 but shows a modification and FIG. 13 is a top view of the modified armature of FIG. 12 taken in the direction of arrow 13-13 of FIG. 12.

Referring to FIGS. 1 and 2 particularly, the rotary magnetic actuator 10 comprises a pair of

opposed pole pieces

11 and 12 and an armature '13 which is centrally bored at 14 to receive a shaft 15 formed of a non-magnetic material upon which the armature is permanently mounted for rotation therewith. The pole pieces and armature are formed of a magnetic material.

The pole pieces are secured to backup plates 16 and the pole pieces and the backup plates are centrally bored at 18 to provide a journal for the ends of the shaft 15.

A means for magnetizing the pole pieces is provided in the form of an electrical coil .19 which surrounds the pole pieces. The structure is covered by a housing 20, and the housing and pole pieces are mounted by any suitable means against rotation.

A return spring 21 is secured to the shaft and may be anchored at one end to the housing or lower backup plate 16 so that the shaft will be returned by the force of the spring to a non-rotated position.

Note, that the two pole pieces, the shaft and the armature are all axially alined along a single axis 22.

The facing ends of the two pole pieces form

pole faces

25 and 26 which are formed in a helical configuration, that is, a screw-like configuration, whose lead direction is parallel to the axis 22 and which are of no more than one lead.

Likewise, the armature is provided with armature faces 27 and 28 arranged to overlap their

adjacent pole faces

25 and 26 respectively. The armature faces are also helical in configuration and each is identical in helical form as its overlapped pole face.

The assembly of the armature and pole pieces is much like that of a screw having only one thread fitted into a threaded socket of only one thread. However, the shaft 15 is held against axial motion by some suitable means, such as a bearing 29, and hence, while the structure is screw-like in configuration, the shaft does not advance as a screw might if it were threaded into a socket, although the armature faces do advance relative to their respective pole faces.

The helical shape, may be varied to different angles and as shown in FIGS. 8 and 9, the armature thread may be completely symmetrical about a horizontal plane through the armature 13a with the pole pieces being correspondingly formed. The changes in helical angle or lead length, affect the output torque and may be varied to produce the particular torque desired.

The operation of the foregoing structure may best be described in relationship to FIGS. 10 and 11 which schematically define the operation. In FIG. 10, the

pole pieces

11 and 12 and armature 13 are shown as if unwrapped and fiat rather than circular as they actually are. The vector diagram shows the forces F being the attractive or magnetic force upon the armature due to magnetization of the pole pieces. F is normal to the pole faces and armature faces which faces are parallel with one another.

In the vector diagram, the force F is composed of an axial force A which tends to move the corresponding faces of the armature and the pole pieces together and a propelling force P. The two opposing axial forces A cancel each other out so that the armature is ordinarily balanced. On the other hand, the propelling force F moves the armature between the pole pieces and provides the turning force or output torque produced by the armature. The force P thus causes the armature to rotate. Since the faces are parallel in their circumferential direction, all of the magnetic flux lines are utilized to produce the propelling force P.

Likewise, as shown in FIG. 11 (and also FIGS. 4 and 5), the faces are preferably arranged parallel in planes X which planes are normal to the shaft axis 22. Thus, all of the flux lines intercepting the transverse or radial elements of surface area are utilized to produce propelling forces P. It can be seen that this configuration utilizes the entire pole faces and armature faces surfaces to produce a usable torque.

In some cases, where it may be desired to locate some of the forces further from the axis 22 so as to cause a greater torque due to a greater moment arm, the pole faces and armature faces may be made to converge towards each other in a direction away from the axis 22 as shown by the dotted lines YY, thus the flux lines would tend to concentrate in an area remote from the axis 22 and because the moment arm is greater, it will produce a greater torque up to the limits of magnetic saturation. The angle between lines YY may also be varied along the length of the pole and armature faces (as seen in stretch out in FIG. to vary the concentration of flux at desired points.

The pitch angle of the various helices may be uniform as illustrated, or may be a constantly varying pitch angle to produce different torque output curves.

Referring to the modification of FIGS. 12 and 13, at times, it may be desirable to have a lead which is of an axial length that may be too unwieldy for any specific use of the actuator. The lead may be shortened by splitting the helices of the pole faces and armature faces into helical portions or helical steps. Thus, FIGS. 12 and 13 show an armature and pole pieces whose surfaces are formed in two helical steps, each step beginning and ending in common planes normal to axis 22. With this construction, the degree of rotation is, of course, reduced, but the particular lead desired can be obtained without increasing the axial dimension of the assembly. Otherwise, the structure here operates in the same manner as that described above.

This invention may be further developed within the scope of the following attached claims. Accordingly, it is desired that the foregoing description be read as being merely an illustrative embodiment of the invention and not in a strictly limiting sense.

We claim:

1. A rotary magnetic actuator comprising a pair of magnetizable pole pieces, the pole pieces being axially alined end to end and each having a pole face opposing the pole face of the other, the pole faces being axially spaced apart; an armature in the form of a thin, diskshaped plate positioned between the two pole faces in axial alinernent therewith, the opposite sides of the plate forming armature faces; said armature being mounted upon a shaft in axial alinement therewith, and central openings being formed in the pole pieces, with the shaf passing through the openings and having its axis coin cident with the pole piece axes; each of the pole faces and adjacent armature faces being of an identical helical formation, the leads of the helices being parallel to the shaft axis and the surfaces thereof being transverse to the shaft axis, the helices on one pole face and its adjacent armature face being the reverse of that of the other pole and armature faces; and means to magnetically energize the pole pieces to cause the armature and shaft to rotate.

2. A rotary magnetic actuator comprising a shaft rotatably'mounted for rotation about its axis and formed of a non-magnetizable material; two magnetizable pole pieces each centrally bored, with the opposite ends of the shaft passing through their central bores and the pole pieces and shaft being axially alined; each of the pole pieces having a pole face with the pole faces facing each other and being spaced apart from one another along the shaft axis, the faces being transverse to the shaft axis and surrounding the shaft, the pole faces each being formed in a helical shape of no more than one helical lead, the leads thereof being parallel to the shaft axis; an armature, of a disk-like shape, positioned in the space along the shaft axis between the two pole faces and being centrally secured to the shaft for rotation therewith, the opposite sides of the armature being formed as armature faces, with each armature face facing and overlapping one of the pole faces, the armature faces being helical in formation and each armature face helix being substantially identical to the pole face which it overlaps; the shaft being held against axial movement; and means to magnetically energize the two pole pieces, wherein the armature faces are magnetically attracted towards their respective pole faces and hence the armature and shaft rotate.

3. A construction as defined in claim 2 and wherein the helices are each so formed that the line on the surface of each helix which generates the helical surface is normal to the shaft axis.

4. A construction as defined in claim 2 and wherein the helices are each so formed that the line elements which generate the helical surface on the surface of one pole face is parallel to the similar line elements on its overlapping armature face.

5. A construction as defined in claim 2 and wherein the helices are each formed so that any two adjacent lines, one drawn on a pole face and the other on its overlapping armature face, which lines intersect the shaft axis, converge towards each other away from the shaft.

6. A construction as defined in claim 2 and said helices each being split into at least two helical portions, each helical portion on each face beginning at one plane which is normal to the shaft axis and ending at a second plane which is also normal to the shaft axis.

7. A rotary magnetic actuator comprising a shaft mounted for rotation about its axis and formed of nonmagnetizable material; a magnetizable pole piece axially alined with the shaft, and an armature centrally mounted upon the shaft for rotation therewith, one of the pole piece ends being formed as a pole face and having a helical configuration of no more than one lead, said lead being parallel to the shaft axis; the armature having an armature face closely spaced to and overlapping the pole face and the armature face being formed in a helical configuration substantially identical to that of the pole face, and means for magnetically energizing the pole piece to thereby cause the armature face to be magnetically attracted to the pole face hence rotating the armature and shaft. 7

8. A rotary magnetic actuator comprising two pole pieces, axially alined with the facing ends of the pole pieces forming pole faces which are spaced apart a predetermined distance along their common axes, each of the faces being shaped in a helical configuration of no more than one helical lead and the two helices being identical, but reversed relative to one another; an armature, in the form of a plate, arranged in the space between the pole faces and being axially alined with the pole piece axes, the opposite faces of the plate forming armature faces, each of which overlap one pole face, each armature face being of a helical configuration substantially identical to the shape of its overlapped pole face and 'each armature face being closely spaced to its respective pole face, and means to magnetically energize the pole pieces so that the armature faces are attracted towards their respective pole faces, thus causing the armature to rotate.

9. A construction as defined in claim 8 and including 2,937,557 5 l a e nailed through at least one of the pole pieces, and the References Cited in the file of this patent armature being secured to the shaft for rotation therewith. UNI

10. A construction as defined in claim 8, and wherein TED STATES PATENTS each of the helices extend substantially a full 360 around 2,289,227 Walker y 1942 the pole piece axes. 5

11. A construction as defined in claim 10 and where- FOREIGN PATENTS in each of said helices are split into at least two helical 1,130,328 France Sept. 24, 1956 portions, to form a single stepped helix configuration. 956,614 Germany I an. 24, 1957