Magnetic actuator construction for a circular knitting machine

Claim 2

In a circular knitting machine having a plurality of knitting elements, each of said elements having at least one ferromagnetic component, the improvement which comprises apparatus for the individual control of any of the knitting elements, the apparatus comprising at least one selector unit which contains a permanent magnet and pole pieces connected therewith, and an electromagnetic unit including an electromagnet and a coil connected therewith, the permanent magnet and its pole pieces, and the electromagnet and its coil being so shaped and arranged with regard to each other and with respect to ferromagnetic component of the knitting elements that they form two substantially separate magnetic circuits whose magnetic fluxes pass parallelly and opposite through a substantial portion of the cross-section of the controlled ferromagnetic component except for the portion associated with the input direction of said magnetic fluxes into said ferromagnetic component wherein said fluxes are substantially perpendicular to each other.

Claim 3

A circular knitting machine comprising a permanent magnet and a rotatable needle bed with the flux path of said permanent magnet positioned symmetrically about a first axis, a magnetically actuable rocking presser through which the flux of the permanent magnet passes to exert an attractive force on the rocking presser along the first axis, means including a stationary cam for moving the rocking presser to the permanent magnet, the permanent magnet attracting the rocker presser into a first position against a restoring force, a normally deenergized electromagnet which when energized weakens the force exerted by the permanent magnet on the rocking presser so that the restoring force moves the rocking presser away from the permanent magnet in the direction of the first axis and into a released position in the periphery of the needle bed, the permanent magnet having poles separated by a first air gap, the electromagnet having a core with poles separated by a second air gap, means isolating the core of the electromagnet from the poles of the permanent magnet so that the flux path established through the core of the electromagnet when the latter is energized does not substantially affect the flux path of the permanent magnet, said last named means disposing the core of the electromagnet symmetrically with respect to the permanent magnet, and the core of the electromagnet being positioned axially relative to said first axis so that the input direction of the flux path of the electromagnet is disposed substantially perpendicular to the input direction of the flux path of the permanent magnet in the rocking presser when the latter electromagnet is energized after which said fluxes are substantially parallel and opposite to each other when passing through a substantial portion of the rocking presser so as to weaken the portion of the flux of the permanent magnet that attracts the rocking presser when the rocking presser is in its said first position.

Claim 4

A circular knitting machine comprising a permanent magnet and a rotatable needle bed with the flux path of said permanent magnet positioned symmetrically about a first axis, a magnetically actuable rocking presser through which the flux of the permanent magnet passes to exert an attractive force on the rocking presser along the first axis, means including a stationary cam for moving the rocking presser to the permanent magnet, the permanent magnet attracting the rocker presser into a first position against a restoring force, a normally deenergized electromagnet which when energized weakens the force exerted by the permanent magnet on the rocking presser so that the restoring force moves the rocking presser away from the permanent magnet in the direction of the first axis and into a released position in the periphery of the needle bed, the permanent magnet having poles separated by a first air gap, the electromagnet having a core with poles separated by a second air gap, means isolating the core of the electromagnet from the poles of the permanent magnet so that the flux path established through the core of the electromagnet when the latter is energized does not substantially affect the flux path of the permanent magnet, said last named means disposing the core of the electromagnet symmetrically with respect to the permanent magnet, and the core of the electromagnet being positioned axially relative to said first axis so that the input direction of the flux path of the electromagnet is disposed substantially perpendicular to the input direction of the flux path of the permanent magnet in the rocking presser when the latter electromagnet is energized after which said fluxes are substantially parallel and opposite to each other when passing through a substantial portion of the rocking presser so as to weaken the portion of the flux of the permanent magnet that attracts the rocking presser when the rocking presser is in its said first position.

Claim 5

A machine as defined in claim 2, wherein the first and second air gaps are disposed coaxially with respect to the direction of movement of the rocking presser and for spacing such air gaps in such direction, the rocking presser having a recess defining a third air gap within which the magnetic fields of the electromagnet and the permanent magnet intersect.

Claim 6

A machine as defined in claim 3, in which the core of the electromagnet is U-shaped and has spaced arms and the permanent magnet is disposed between the arms of the core of the electromagnet with the pole structures and of the two magnets aligned relative to each other.

Claim 7

A machine as defined in claim 4, wherein said isolating means include standoff means for preventing impact between the rocking presser and the pole pieces of the permanent magnet while the electromagnet remains unenergized, the axial length of the standoff means being chosen to establish the minimum axial distance between the rocking presser and the first air gap at a value less than the axial spacing between the first and the second air gaps.

Claim 8

A machine as defined in claim 5, in which the standoff means comprises an element extending axially from the first air gap of the permanent magnet and engageable with the recess of the rocking presser.

Claim 9

A machine as defined in claim 5, in which the standoff means comprises a pair of spacers extending axially between the first and second air gaps and radially between opposite outer surfaces of the permanent magnet and respectively adjacent inner surfaces of the electromagnet.

Claim 10

A machine as defined in claim 4, in which the machine has a rotatable circular bed on the periphery of which the rocking pressers are disposed, and the permanent magnet and the electromagnet are disposed in radially spaced relation to the periphery.

Claim 11

The machine as defined in claim 2, in which the permanent magnet has a pole structure, the electromagnet has a core, and the pole structure is mounted outside the core of the electromagnet, the pole structure and the core being axially aligned, the flux of the electromagnet being oriented oppositely from the flux of the permanent magnet.

Claim 12

A machine as defined in claim 9, further comprising standoff means for preventing impact between the rocking presser and the pole structure of the permanent magnet while the electromagnet remains unexcited, the axial length of the standoff means being chosen to establish the minimum axial distance between the rocking presser and the first air gap at a value less than the spacing between the first and the second air gaps.

Claim 13

A machine as defined in claim 9, in which the machine further comprises a rotary needle cylinder on the periphery of which the rocking pressers are disposed, and wherein the permanent magnet and the electromagnet are disposed outwardly the periphery of the needle cylinder in radially spaced relation with respect thereto.