US2448727A

US2448727A - Solenoid with armature

Info

Publication number: US2448727A
Application number: US528194A
Authority: US
Inventors: Oetsel John George
Original assignee: Warner Electric Brake Manufacturing Co
Current assignee: Warner Electric Brake Manufacturing Co
Priority date: 1944-03-27
Filing date: 1944-03-27
Publication date: 1948-09-07
Anticipated expiration: 1965-09-07

Description

Sept. 7, 1948. J. G. OETZEL 2,448,727

SOLENOID WITH ARMATURE Filed larch 27, 1944 Patented Sept. 7, 1948 244cm SOLENOID wrrn ABMATUBE John George Oetael, Belolt, Wis., sssignor to Warner Electric Brake Manufacturing Company, Beloit, Wls., a corporation of Illinois Application March 21, 1944, Serial No. 528,194

The present invention pertains to solenoids and the general aim of the invention is to provide a new and improved solenoid which is capable of exerting an unusually high force in proportion to its size and weight.

Another object is to provide a novel solenoid having an armature concentric with the radially facing pole pieces with which it coacts, the arma- 17 Claims. '(Cl. 175-337) ture and pole pieces being relatively movable in an axial direction.

A more detailed object is to provide a solenoid which has a passing type armature and in which the adjacent portions of the armature and pole pieces are shaped relative to each other to effect a progressive diminution in reluctance to flow of flux between the pole pieces and through the armature as the latter moves under the influence of such flux.

Another object is to provide a solenoid having a plurality of pairs of outwardly facing pole pieces and an armature ring disposed externally of said pieces and presenting opposite each pole face a surface which is inclined relative thereto.

A further object is to provide a novel solenoid of the above character which lends itself to multiplication of active pole faces to any number desired.

Another object of this invention is to provide a solenoid incorporating a sectional winding and pole pieces intermediately disposed between the winding sections and cooperatively associated with an armature of variable section and reluctance normally biased to displacement along the pole pieces in such a way that energization of the winding efi'ects relative movement between the pole pieces and armature against the normal biasing force.

Still another object is to provide a solenoid of the general character indicated embodying a novel arrangement of the parts which facilitates the winding of its actuating coil or coils.

The invention also resides in various structural improvements by means of which over-all strength and rigidity are achieved in a structure of small size and weight.

Further objects and advantages of the invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings in which:

Figure 1 is a vertical sectional view of a solenoid embodying a preferred form of the invention.

Fig. 2 is an exploded perspective view of the solenoid of Fi 1.

Fig. 3 is an enlarged fragmentary sectional.

view, corresponding to the lower portion of Fig. 1, and indicating the mean path of fiux flow.

Fig. 4 is a fragmentary sectional view of a structure embodying the invention in a modified form, and indicating the mean path of flux flow therein.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the inventlon'as expressed in the appended claims.

In the exemplary embodiment of the invention illustrated in Figs. 1, 2, and 3 of the drawings, the solenoid there shown comprises as its principal elements a core Ill made of suitably magnetizable material and an armature I I having portions made of magnetizable material, as will more fully be described. The core in of this preferred form consists of two concentric ring-shaped members I! and I! having flanges Ila and "a respectively at adjacent ends thereof which are bolted together in overlapping relation so that the members define between them an annular pocket H' in which is received the annular or drum-shaped armature H.

In the operation of the solenoid the core l0 and armature ll move relative to each other in an axial direction, one being secured to a support and the other positioned to move some member which is to be actuated. As here illustrated, the core structure I0 is bolted by means of an internal mounting flange I'Zb on the inner ring 12 to a stationary support shown fragmentarily as two annular members l5, l6, whereas the armature l I is axially movable to displace any suitable driven element (not shown) that a particular use of the solenoid ma require.

To support the armature ll concentrically with the core i0, and for movement axially oi the same, the flanged outer end I la of the armature is slidably received on a mounting ring I? of channel-shaped cross-section, fixed to the inner core ring l2. This mounting ring I! is made of suitable non-magnetic material such, for example, as brass, so as to minimize flux leakage through it.

The armature II is yieldably urged inwardly toward the bottom of the pocket I by suitable spring means and when the solenoid is energized the armature tends to move outwardly against such spring bias, as will hereinafter appear. Such spring means includes, in the present instance, a ring l8 clamped between the inner core ring I! and the supporting member I 6 and having thereon a plurality of generally radially projecting integral spring fingers l 8a bent to engage the outer end 01' the armature II and thus urge the armature axially and inwardly into the pocket I4. Such inward movement of the armature is limited by means of positive mechanical stops, shown as comprising stop pins l9 fixed to the ring flange Ma and received within registering sockets l9a 3 in the inner edge of the armature. These stop pins l9, like the guide ring H, are. preferably aua-rar 4 of'the armatureand pole faces are separated by two tapering air gaps of reluctances which vary made oi non-magnetic material to minimize any leakage of flux through them and are of sumcient length to space the innerend of the armature from the adjacent portion of the core to minimize fringing or leakage of flux between the armature and the inner end of the core.

Opposed pole pieces, preferably in a plurality of pairs spaced longitudinally of the armature I I, are provided on the core structure it. Desirably, these pole pieces are annular external ribs on the inner core ring l2 having peripheral surfaces which face radially outwardly and register with the opposed internal faces of annular ribs 2| on the outer core ring it. The ribs 20 and 2| may either be integral with the rings l2 and I3, respectively, or may be separately made and pressed onto or otherwise secured to the respective rings. In the present instance, the ribs 20 are of somewhat greater radial width than the opposed ribs 2| in order to furnish adequate space for energizing windings 22. The latter are located in the grooves or channels between the ribs 20 and adjacent the end flange |2a on the inner core ring l2. In constructing the solenoid, the windings 22 may be wound in place on the exterior of the ring l2 prior to bolting the exterior ring I3 to the latter, or when separately made ribs 20 are used, the windings may be prewound and assembled onto the ring alternately with the ribs, thus simplifying the formation and installation of the windings.

Various mounting arrangements for the terminals of the windings 22 may be employed. Herein, a strip of insulating material 25 which serves as a mounting block for terminals 26, 21 (Fig. 1) is secured to the inner core ring i2. The three windings being connected in parallel, only two terminals are required for making connections to the windings.

The mean path of flux set up by the windings 22 is indicated by the arrow lines in Fig. 3. Having in mind that Fig. 3 is a sectional view, it will be apparent that the mean paths throughout the solenoid are of more or less toroidal shape and embrace the respective windings. Either direct or alternating current may be used for energizing the windings 22, the former being preferred for the illustrated device since its core structure is not laminated. As appears from the flux paths indicated in Fig. 3, the flux flows in orbital paths, passing from one pole piece to the opposed pole piece radially through the armature, such opposed pole pieces being of opposite polarity and formed respectively by the projections 20 and 2| on the inner and outer members l2 and I3. By way of example, north and south poles-may be induced as indicated by the letters N and "S" in Fig. 3.

The armature and each of the adjacent portions of the core pole pieces are constructed and arranged for coaction to effect a progressive decrease in reluctance to the flow of flux between the opposed pole pieces as the core and armature move axially relative to each other in one direction from the normal position illustrated. For this purpose, integral annular rings 28 of magnetizable material having a tapered or wedge-like section are provided in the armature l|, one for each pair of pole pieces on the core. In each instance, these rings 28 have abrupt. or substantially radial end faces and angularly disposed or gently sloped faces 28a disposed opposite thecylindrical faces of the coacting pair of pole pieces 20 and 2 I. In this way, the active portions progressively along the armature in an axial direction. The rings 28 are supported and secured together by a ring-like supporting and spacing member 20 which is preferably made of nonmagnetic material, such as brass, and notched as at to receive the rings 2l-and hold them in spaced relation to minimize flux leakage between the pole pieces through the armature. The rings 2| are preferably secured in place in the member 29 by non-magnetic welding or brazing- 2|. In consequence of the shape of the parts described. the reluctance to flow of flux between the opposed pairs of pole pieces is diminished as the armature moves to the right (as viewed in Fig. 3).

By reason of the high reluctance between the opposite ends of the armature II and the adjacent portions of the core, as well as between the saparated rings 20, substantially all of the flux threading the core and armature structure is compelled to flow in the paths indicated in Fig. 3. In so doing, it passes transversely through the rings of magnetizable material in the armature and links the opposed pole pieces. Since the flux follows in the path of least reluctance, it tends to pass through the rib portions of the armature as indicated, and the flux lines tend to straighten, producing an endwise force that urges the armature to the right as viewed in Fig. 3 or, in other words, in a direction to minimize the air gaps and thus the reluctance.

Referring to the modified form of the invention illustrated in Fig. 4, the solenoid comprises a core 40 and an armature 4| which are both made of a suitable magnetizable material. The

core 40 includes a ring-like base or connecting portion 42 which has thereon a plurality of pole pieces 43 which preferably project outwardly from the base or connecting portion 42 and may be integral therewith or separately made and suitably secured in position. The pole pieces 43 are axially spaced to provide intermediate channels for winding sections 44. The winding sections 44 may be wound in place when the pole pieces are integral portions of the core, or may be separately prewound and assembled onto the core when separately made pole pieces are utilized. The core 40 is supported by a non-magnetic bracket 45 and is secured thereto by a bolt 46 having a cooperating spacer 41 for positioning the core with respect to the support.

The armature 4| is also generally circular in shape and is concentric with respect to the core 40 and the projecting ends of the pole pieces 43. This armature has an inner surface adjacent the core 40 which is shaped or notched to provide similar gradually sloped surfaces, such as 48, opposed to the end or pole face of each of the pole pieces 43 and connected by abrupt or radial intervening surfaces. The armature is biased by means not shown to a position such as that illustrated and in which the heavier or thicker portions of the armature are disposed to the sides of the pole pieces toward which the armature is biased. The outer surface of the armature 4| is generally cylindrical.

'of non-magnetizable or magnetizable material,

is secured to a support or bracket 45 by means such as a bolt 53. The armature ll carries a member 54 which is adapted to be connected to a device which is to be actuated by the movement of the armature. Lugs, such as ll, on the outer end surface of the armature engage the member 54 to insure the movement of the member 54 with the armature during operation.

The mean flux paths in this modified form of the invention, are somewhat different from those disclosed in connection with the preferred embodiment shown in Figs. 1, 2, and 3, although the principle of operation of the solenoid is similar. The armature in this instance provides the return or connecting path between the ends of the pole pieces 43. However, since the tapered or sloped portions of the armature are normally disposed in positions such that the air gaps at the ends of the pole pieces are longer than when the armature is moved to the right, as shown in Fig. 4, the tendency of the flux is to urge the armature to a position such that the air gaps and the resulting reluctances of the flux paths are reduced. It is to be noted that the windings are arranged in such a way that the polarities of the pole pieces alternate. Also, as in the previously described form, the pole pieces and the coacting portions of the armature are constructed and arranged to effect a progressive decrease in the reluctance to the flow of flux through the armature between adjacent pole pieces as the core and armature move axially relative to each other in one direction.

Even though there is a diminution of the air gaps as the armature moves, the described construction provides a flow of flux that achieves a high degree of uniformity of force on the armature throughout a reasonably long range of permitted movement of the armature. Such range is limited in the advancing direction for the armature (to the right in Figs. 3 and 4) by stops or otherwise, so that the armature is never permitted quite to touch the pole pieces or pass beyond the position of maximum pull due to inertia. In the retraction of the armature the range is limited by the stops IS, in Fig. 3, to a point such that even when the armature is fully retracted no substantial amount of flux will leak from its inner end to the adjacent portion In of the core.

When the windings are deenergized the armature is held in its retracted position by springs not shown in Fig. 4. Upon energization of the windings 22, the armature is magnetically pulled toward its projected position against the bias of the springs. Open-circuiting the windings permits the springs to restore the armature to its initial or retracted position.

I claim as my invention:

1. In an electric solenoid, the combination of a pair of concentric generally annular magnetizable members magnetically connected at one end and having radially alined pole pieces facing inwardly and outwardly and defining circular air gaps between their opposed faces, an energizing winding for inducing magnetic poles of opposite polarity in said opposed pole pieces to cause flux to pass therebetween through said gaps, an annular armature disposed in said gaps and providing a radial path for the flux threading between said opposed faces, and means supporting said core and armature for relative axial movement, the adjacent surfaces of said armature and pole pieces being shaped to effect a progressive change in the spacing oi the armature from said pole pieces as the armature and pole pieces move axially relative to each other.

2. In an electric solenoid, the combination of a core presenting a pair of annular radially alined pole pieces of opposite polarity with an air gap between their opposed faces, means including an energizing winding for causing flux to pass through said gap between said pole pieces, and an annular armature mounted in said air gap for movement relative to the core in a direction transverse to the path of flux linking said pole pieces and having a reluctance which is difierent at successive points along the armature in the direction of its movement, said armature serving as a radial path for said flux between said pole pieces.

3. In an electric solenoid, the combination of a core presenting a pair of annular radially alined pole pieces of opposite polarity with an air gap between their opposed faces, means including an energizing winding for causing flux to pass through said gap between said pole pieces, and an annular armature mounted in said air gap for movement relative to the core in a direction transverse to the path of flux linking said pole pieces, the portion of said armature located between said pole pieces being tapered in the direction of armature movement, said armature serving as a radial path for said flux between said radially alined pole pieces.

4. In an electric solenoid, the combination of a core having a plurality of pairs of annular radially projecting pole pieces thereon presenting opposed concentric faces separated by an annular air gap, means for inducing in said pole pieces magnetic poles of opposite polarity to cause flux to thread said gap, an annular armature disposed in the gaps between each pair of pole pieces, and means supporting said armature for movement past said pole faces in a direction substantially paralleling the latter and generally normal to the path of flux linking such pole faces, the portion of said armature between each pair of pole faces having a reluctance which is diii'erent at successive points spaced axially in the direction of its movement.

5. In an electric solenoid, the combination of a core presenting a plurality of axially spaced pairs of pole pieces with the faces of each pair opposing each other, an armature disposed in the air gaps between the successive pairs of pole pieces, said armature and pole pieces being shaped relative to each other to gradually diminish the air gaps between the armature and each pair of pole pieces as the armature and core move relative to each other across said pole faces in one direction, and means for inducing magnetic poles of opposite polarity in the pole pieces of each pair.

6. A solenoid having, in combination, a magnetizable core comprising a plurality of axially spaced radially disposed rings, an annular magnetic member joining said rings at corresponding peripheral edges, an annular winding disposed between the adjacent rings and energizable to produce magnetic poles of alternate polarity at the unjoined peripheral edges of the rings, an armature concentric with the faces of said poles, said pole faces and the opposed surface of said armature being separated by an air gap which tapers axially of said rings, and means supporting said core and armature for relative axial movement.

'7. In an electric solenoid, the combination of a magnetizable core structure defining an annular aerate? outwardly rojecting ole piece with its periphery facing outwardly, a tapered armature ring enclosing said peripheral face, said ring being movable axially and providing a permeable path for the fiux passing through said pole piece which increases in radial thickness upon said ring being subjected to axial movement, a winding for energizing said pole piece, and means providing a return path for the flux threading said pole piece and armature ring.

8. In an electric solenoid, the combination of a magnetizable core structure comprising c'oncentric inner and outer rings having their adjacent side walls spaced apart to form an air gap therebetween, means forming a low reluctance flux path between said rings at only one end of said gap, a generally drum-shaped armature projecting into said air gap from the open end thereof, means supporting said core structure and said armature for relative axial movement, said inner and outer core rings having a plurality of axially spaced ribs projecting radially with the faces of the ribs on one ring opposed to those on the other ring to define poles thereon and radially spaced apart to receive said armature between them, and an energizing winding wound about the exterior of said inner core ring in the space between two of the ribs thereon.

9. In an electric solenoid, the combination of a magnetizable core structure presenting a pair of concentric generally annular pole pieces defining a circular air gap between opposed faces thereof, said core structure including a portion joining said pole pieces remote from said gap, an energizing winding for inducing magnetic poles of opposite polarity in said pole pieces to cause fiux to pass therebetween, an annular armature disposed in said gap in the path of flux threading between said pole pieces, and means for supporting said core and armature for relative axial movement, said armature having an annular rib presenting a side inclined relative to the face of said pole pieces.

10. A solenoid having, in combination, a magnetizable core comprising a plurality of axially spaced radially disposed rings magnetically joined at one peripheral edge, an annular winding disposed between the adjacent rings and energizable to produce on the other peripheral edges of the rings magnetic poles of alternate polarity, an armature concentric with the faces of said poles, the surfaces of said armature opposite said pole faces being frusto-conical to define air gaps which taper axially of said rings, and means supporting said armature for axial movement.

11. In an electric solenoid, the combination of a magnetizable core structure comprising concentric inner and outer rings having their adjacent side faces spaced apart to form an air gap 'therebetween, means forming a low reluctance flux path between said rings at only one end of said gap, a generally drum-shaped armature projecting into said air gap from the open end thereof, means supporting said core structure and said armature for relative axial movement, said inner and outer core rings having a plurality of annular ribs on their adjacent faces disposed with those on one ring radially alined with those on the other to define pole pieces thereon and radially spaced apart to receive said armature between them, and an energizing winding disposed about the exterlor of said inner core ring in the space between two of the ribs thereon, said armature having annular ribs thereon equal in number to the number of ribs on each of said dill Kilt

core rings and displaced axially from the latter, said armature ribs providing sidefaces disposed opposite the respective pole faces and inclined relative to the latter. I

12. In an electric solenold,,the combination of a magnetizable core providing an annular outwardly facing pole, an armature ring encircling said pole and urged axially by flux threading the two, and a nonmagnetic ring fixed to said core and guiding said armature for axial sliding movement.

13. In an electric solenoid, the combination of a magnetizable core structure including a pair of concentric annular pole pieces defining a circular air gap between opposed faces thereof and an interconnecting magnetic member bridging said pole pieces, an annular armature disposed in said gap between said pole pieces, an energizing winding for inducing magnetic poles of opposite polarity in said pole pieces to cause flux to link said pole pieces through said armature, and means including a nonmagnetic stop between said armature-and said interconnecting magnetic member for limiting the movement of said armature with respect to said magnetic member.

14. In an electric solenoid, the combination comprising an electromagnet having windings and pole pieces disposed side by side and alternating with each other, said pole pieces being joined on one side of said windings by magnetizable material and having exposed pole faces on the other side of the winding, and an armature having active faces angularly disposed with respect to each of the pole faces, said armature being supported adjacent the pole faces in a normal position such that energization of the electromagnet tends to move the angularly disposed faces across said pole faces in a direction to reduce the widths of the gaps between the armature and pole faces.

15. In an electric solenoid, the combination comprising an electromagnet having a channeled core member providing a pair of connected pole pieces and an energizing winding disposed in the channel between said pole pieces, and an armature having substantially wedge-shaped sections of magnetizable material adjacent the ends of each of the pole pieces and supported for movement across the ends of the pole pieces, said wedge-shaped sections being biased to normal positions in which the thinner portions of the wedges are adjacent the pole pieces.

16. In an electric solenoid the combination comprising a plurality of pairs of oppositely disposed pole pieces having air gaps therebetween, an armature comprising a plurality of magnetizable members each of wedge-like section and respectively disposed between the pairs of pole pieces, said wedge-like sections being wider than the pole pieces and normally positioned with the thin end of the section between the pole pieces, and non-magnetic means supporting and connecting said members for movement transverse to the pole pieces.

17. In an electric solenoid, an armature comprising a plurality of annular magnetizable members of axially tapered section arranged side by side, means including a nonmagnetic support for maintaining said annular members in spaced relation and rigidly fastened to one another to form a unitary cylinder, magnetic structure including a plurality of separately energized annular electromagnets arranged side by side and presenting their poles to said annular magnetizable members, the cyclical distance measured axially between adjacent ones of sad magnetizable members being the same as the cyclical distance between corresponding electromagnets to cause substantially equal translating iorces to be simultaneously and cumulatively exerted by respective ones of said magnetirable members.

JOHN GEORGE OETZEL.

REFERENCES CITED The following references are of record in the file of this patent:

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