US2731605A

US2731605A - Wind-up coil

Info

Publication number: US2731605A
Application number: US284081A
Authority: US
Inventors: Melvin L Doelz
Original assignee: Collins Radio Co
Current assignee: Collins Radio Co
Priority date: 1952-04-24
Filing date: 1952-04-24
Publication date: 1956-01-17
Anticipated expiration: 1973-01-17

Description

Jan. 17, 1956 M. L. DOELZ WIND-UP COIL Filed April 24, 1952 IN VEN TOR. 4412 r1 l 00!; z

Ar razwner WIND-UP COIL Melvin L. Doelz, Glendale, Califi, assignor to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Application April 24, 1952, Serial No. 284,081

3 Claims. (Cl. 336-15) This invention relates to a variable inductor.

In electronics it is oftentimes desirable to use a variable inductance. Variable inductances may be constructed with a slide contact which engages a Wound inductance. The contact may be connected electrically to one end of the coil so as to short out those turns between the slide contact and the end. The remaining turns are the effective ones. Even though some of the turns are shorted out, mutual inductance exists between them and the active turns.

It is an object of this invention, therefore, to provide means for physically separating shorted and effective turns of a variable inductance.

Another object of this invention is to provide means for increasing the Q obtainable with a variable inductance.

Yet another object of this invention is found in the provision for a rotatably supported coil form about which is wound two portions of conductors. A pair ofrollers are mounted between the portions.

A feature of this invention is found for coil.

Further objects, features, and advantages of this invention will become apparent from the following description and claims when read in view of the drawings, in which:

Figure l is a side view of the variable inductance of this invention, and

Figure 2 is a top view of the variable inductance.

Figure 1 shows a base plate 10 which has

end plates

11 and 12 mounted thereon. The end plates may be made of insulating material, as for example, Bakelite.

Rotatably supported between the

end plates

11 and 12 is a coil form 13 which may be supported by an axle 14. A pair of

lead screws

16 and 17, respectively, extend from

end plates

11 and 12 parallel to the coil form 13 and are rotatably supported in the end plates.

A driving means 18, as for example, an electric motor. is mounted to the base plate 10 by'stand-

oifs

19 and 21 and has an output gear 22. The coil form 13 supports a gear 23 which meshes with driving gear 22. The

lead screws

16 and 17

support gears

24 and 26, which mesh with the gear 23.

A roller assembly 27 has a pair of threaded

projections

23 and 29 that engage the

lead screws

16 and 17, respectively. A pair of

rollers

31 and 32, respectively, are supported on the member 27 at an angle.

The roller 31 is mounted in a bearing 33, as best shown in Figure 2, and the roller 32 is mounted in a bearing 34 which is movable in a slot 36 formed in the member 27. A spring 37 biases the bearing 34 away from the roller 31.

A flexible conductor 38 is wound about the coil form 13 and has one end attached to a band 39. An output contact 41 is mounted on the plate 11 and engages the band 39. The conductor 38 is wound about the coil form 13 until it is immediately below the roller 31 and then passes up over the roller 31 and between a pair of

flexible contacts

42 and 43 carried on the member 27. it then passes over the roller 32 and back around the in the provision means that physically separate two portions of a respectively,

:ited States Patent opposite end of the coil form ductive band 44.

A slide contact 46 is mounted on the end plate 12 and contacts the band 44. Extending between

end plates

11 and 12 is a conductive rod 47 and a flexible slide contact 48 extends from the member 27 to engage the rod 47. The contact 48 is electrically connected to the

contacts

42 and 43.

A terminal 49 is connected to the member 47.

In operation, electrical connections are made to contacts 41, 46 and 49.

Contacts

49 and 41 might be connected together so as to short out the turns at one end of the coil. The position of the member 27 is controlled by the

lead screws

16 and 17 which are driven by the motor 22 through the

gears

23, 24 and 26. The

gears

23, 24 and 26 are formed so that the member 27 moves at the correct speed longitudinally of coil form 13 as the coil form is rotated.

As the coil form is rotated, the number of turns at one side of the coil will be increased and those at the other side will be decreased. If it is assumed that the

contacts

41 and 49 are connected together, then those to the left of Figure 1 will be shorted by the member 27 and those to the right will be the effective turns.

It is to be noted that the shorted turns are physically separated from the active turns by the distance between the outer edges of the

rollers

31 and 32. As is well known to those skilled in the art, physical separation decreases mutual inductance between a pair of coils and thus the mutual inductance will be substantially less than in a coil where the shorted turns are kept immediately adjacent the active coils. This results in an inductance of high inertia and gives a higher Q than is obtained with less physical separation.

Although this invention has been described with respect to a particular embodiment thereof, it is not to be so limited as changes and modifications may be made therein which are within the full intended scope of the invention, as defined by the appended claims.

I claim:

1. Apparatus comprising, a base plate, a pair of end plates attached to said base plate, a coil form of insulating material rotatably supported between said end plates. a pair of lead screws rotatably supported between said end plates, a roller assembly threadedly supported by the pair of lead screws, a pair of rollers mounted on the roller assembly, a flexible conductor wound about one end of said coil form, passing over the rollers and wound about the opposite end of said coil form, a first wiper contact mounted to one end plate and engageable with one end of said flexible conductor, a second wiper conductor attached to the other end plate and engageable with the opposite end of said coil, 2. third wiper contact mounted on said roller assembly and engage-able with said flexible conductor between the rollers, a driving means connected to said coil form and said pair of lead screws, a conducting bar mounted between said end plates, and a fourth slide contact extending from said roller assembly to said conductor bar.

2. A variable inductor comprising, a base plate, a pair of end plates mounted on said base plate, a coil form of insulating material rotatably supported between said end plates, a pair of lead screws rotatably supported between said end plates, a roller assembly threadedly received on said lead screws, a pair of rollers supported by said roller assembly so that their planes make an obtuse angle, one of said rollers movable transversely of said roller assembly and spring biased away from the other roller, a pair of conducting bands attached adjacent opposite ends of said coil form, a flexible conductor attached to one of said conducting bands and wound about one end of said coil form, said flexible conductor passing over the first until it connects to a conroller and around the second roller, and then wound about the opposite end of the coil form and connected to the other conducting band, a first Wiper contact mounted on said first end plate and engageable with said first conductive band, a second wiper contact connected to the other end plate and engageable with the other end band, a third wiper contact mounted to said roller assembly and engageable with said flexible conductor between said rollers, a conductive shaft extending between said end plates, a fourth wiper contact connected to said third wiper contact and engaging said conducting shaft, and a driving means connected to the pair of lead screws and the coil form.

3. Movable carriage means for winding and unwinding a flexible wire received on opposite ends of a single rotat'able coil form supported by a frame member comprising, a pair of threaded shafts rotatably supported adjacent said coil form by said frame, gears fixedly provided on said coil form and threaded shafts in meshed relationship to relatively rotate them with the pitch of said threaded shafts and said wound Wire actuated in the same direction, threaded projections secured to said carriage and received on said threaded shafts, a pair of pulleys supported rotatably at opposite ends of said carriage and each inclined toward and receiving said flexible wire, said flexible wire received in an S-form over the outer portions and between said pulleys, a contact fixed on said carriage and slidably contacting the flexible wire as it passes between said pulleys, and said pulleys spring biased away from each other transversely of said coil axis whereby said flexible wire is maintained taut at all times.

References Cited in'the file of this patent UNITED STATES PATENTS 1,642,488 Clausen Sept. 13, 1927 2,037,061 Bliss Apr. 14, 1936 2,175,554- Bliss Oct. 10, 1939