Magnetic gap construction

A magnetic pole structure comprising

• a first end portion fabricated from a material having low reluctance and including
• a cylindrical inner surface having an axis and a diameter, and
• an end surface extending transversely to said axis,
• a second end portion fabricated from a material having low reluctance and including
• a cylindrical inner surface having an axis and a diameter substantially equal to the diameter of said cylindrical inner surface of said first end portion, and
• an end surface extending transversely to said axis, and
• a middle portion fabricated from a material having high reluctance and including
• a cylindrical inner surface having an axis and a diameter substantially equal to the diameter of said cylindrical inner surface of said first end portion, and axially spaced first and second end surfaces extending in radially outwardly diverging relation to each other from said middle portion cylindrical inner surface,
• said first end surface of said middle portion being fixed to said end surface of said first end portion and said second end surface of said middle portion being fixed to said end surface of said second end portion so that said inner cylindrical surfaces are located in coaxial relation to one another and so as that the axial length of said material of high reluctance increases with increased radial distance from said axes.

A method of constructing a magnetic flux gap comprising

• fabricating a first portion from a material having low reluctance and so as to provide
• an end surface, and
• a cylindrical inner surface having a diameter,
• fabricating a second portion from a material having high reluctance and so as to provide
• axially spaced first and second end surfaces, and a cylindrical inner surface having a diameter greater than the diameter of said cylindrical inner surface of said first portion,
• fabricating a third portion from a material having low reluctance and so as to provide
• an end surface, and
• a cylindrical inner surface having a diameter substantially equal to the diameter of said cylindrical inner surface of said first portion,
• fixing together the first and second portions with the first end surface of the second portion fixed to the end surface of the first portion and with said cylindrical inner surfaces in concentric relation,
• fixing together the second and third portions with the second end surface of the second portion fixed to the end surface of the third portion and with said cylindrical inner surfaces in concentric relation,
• whereby to define a magnetic flux gap radially inwardly of the cylindrical surface of the second portion.

A method of constructing a magnetic flux gap comprising

• fabricating a first portion from a material having low reluctance and so as to provide
• a cylindrical inner surface having an axis and a diameter, and
• a surface extending transversely to said axis,
• fabricating a second portion from a material having high reluctance and so as to provide
• a cylindrical inner surface having an axis and a diameter substantially equal to the diameter of said cylindrical inner surface of said first portion, and
• axially spaced first and second end surfaces extending in radially outwardly diverging relation to each other from the second portion cylindrical inner surface,
• fabricating a third portion from a material having low reluctance and so as to provide
• a cylindrical inner surface having an axis and a diameter substantially equal to the diameter of said cylindrical inner surface of said first portion, and
• an end surface extending transversely to said axis, and
• fixing the second portion to the first and third portions so that the inner cylindrical surfaces are located in coaxial relation to one another and so as that the axial length of the material of high reluctance increases with increased radial distance from the axis.

A method of constructing a magnetic flux gap comprising

• fabricating a first portion from a material having low reluctance and so as to provide
• an axially outer end surface, and
• a radially outer end surface extending radially outwardly in axially inward relation to the axially outer end surface of the first portion,
• fabricating a second portion from a material having high reluctance and so as to provide axially spaced axially inner and outer end surfaces,
• fabricating a third portion from a material having low reluctance and so as to provide
• an axially inner end surface, and
• a radially outer end surface extending radially outwardly in axially inward relation to the axially outer end surface of the third portion,
• fixing together the first and second portions with the inner end surface of the second portion fixed to the radially outer end surface of the first portion, and
• fixing together the second and third portions with the outer end surface of the second portion fixed to the radially outer end surface of the third portion,
• whereby to define a magnetic flux gap radially inwardly of the second portion and between the axially outer and inner end surfaces of the first and third portions.

A method of constructing a magnetic flux gap comprising fabricating a first portion from a material having low reluctance and so as to provide an axially outer end surface, an outer cylindrical surface extending axially inwardly from the outer end surface and having a diameter and an inner end, and a radially outer end surface extending radially outwardly from the inner end of the outer cylindrical surface and having a radially extending length, fabricating a second portion from a material having high reluctance and so as to provide axially spaced axially inner and outer end surfaces, an inner cylindrical surface extending between the end surfaces of the second portion and having a diameter greater than the diameter of the outer cylindrical surface of the first portion, and an outer cylindrical surface spaced from the inner cylindrical surface at a distance greater than the radial length of the radially outer end surface of the first portion, fabricating a third portion from a material having low reluctance and so as to provide an axially inner end surface, an outer cylindrical surface extending axially outwardly from the inner end surface and having an outer end, and a radially outer end surface extending radially outwardly from the outer end of the outer cylindrical surface of the third portion and having a radially extending length substantially equal to the first mentioned radially extending length, fixing together the first and second portions with the inner cylindrical surface of the second portion in radially overlying adjacent relation to the outer cylindrical surface of the first portion, and with the inner end surface of the second portion fixed to the radially outer end surface of the first portion, and fixing together the second and third portions with the inner cylindrical surface of the second portion in radially overlying adjacent relation to the outer cylindrical surface of the third portion, and with the outer end surface of the second portion fixed to the radially outer end surface of the third portion, whereby to define a magnetic flux gap radially inwardly of the inner cylindrical surface of the second portion and between the axially outer and inner end surfaces of the first and third portions.