Method and apparatus for tuning a multiturn induction heating coil

Claim 2

In an induction heating device including a multi-turn induction heating coil having a central axis, an outer periphery and spaced ends, a first conductor connected onto one of said ends and extending axially of said coil and adjacent said periphery, and a second conductor connected onto the other of said ends, said conductors being adapted for connection to an alternating current power supply means for energizing said coil whereby current flow in said first conductor and said coil results in a mutual inductance between said first conductor and said coil and affects the reactance of said first conductor, the improvement comprising: means for adjustably shifting said first conductor with respect to said coil periphery to change the mutual inductance between said firsT conductor and said coil.

Claim 3

The improvement as defined in claim 1 wherein said adjustable shifting means includes means for shifting said first conductor in a direction generally radial of said coil.

Claim 4

The improvement as defined in claim 1 wherein said adjustable shifting means includes means for shifting said first conductor in a direction generally normal to a plane defined by the axis of said coil.

Claim 5

In an induction heating installation including a multi-turn induction heating coil having several turns, a central axis and spaced ends, a pair of leads, each of which is electrically connected adjacent one of said spaced ends of said coil, a source of alternating current having two generally fixed output bus, means for connecting one of said leads to each of said generally fixed output bus, wherein said leads extend generally axially of said coil and adjacent said coil and whereby the fields around said leads are inductively coupled with the fields around the turns of said coil, the improvement comprising: means for adjusting the spacing between said leads and said coil to vary the inductive coupling between said leads and said coil turns.

Claim 6

In an induction heating installation including a multi-turn induction heating coil having several turns, a central axis and spaced ends, a pair of leads, each of which is electrically connected adjacent one of said spaced ends of said coil, a source of alternating current having two generally fixed output bus, means for connecting one of said leads to each of said generally fixed output bus, wherein said leads extend generally axially of said coil and adjacent said coil and whereby the fields around said leads are inductively coupled with the fields around the turns of said coil, the improvement comprising: means for adjusting the spacing between said leads and said coil to vary the inductive coupling between said leads and said coil turns.

Claim 7

In an induction heating device including a multi-turn induction heating coil having a central axis, an outer periphery and spaced ends, a first conductor connected onto one of said ends and extending axially of said coil and adjacent said periphery, a second conductor connected onto the other of said ends, said conductors being adapted for connection to an alternating current power supply means with two output leads for energizing said coil whereby current flow in said first conductor and said coil results in a mutual inductance between said first conductor and said coil and affects the reactance of said first conductor and a power factor correcting capacitor connected across said output leads, the improvement comprising: means for adjusting the mutual reactance between said first conductor and said coil to tune said coil with said capacitor.

Claim 8

In an induction heating device including a multi-turn induction heating coil having a central axis, an outer periphery and spaced ends, a first conductor connected onto one of said ends and extending axially of said coil and adjacent said periphery, a second conductor connected onto the other of said ends, said conductors being adapted for connection to an alternating current power supply means with two output leads for energizing said coil whereby current flow in said first conductor and said coil results in a mutual inductance between said first conductor and said coil and affects the reactance of said first conductor and a power factor correcting capacitor connected across said output leads, the improvement comprising: means for adjusting the mutual reactance between said first conductor and said coil to tune said coil with said capacitor.