Prime mover and methods

Claim 1

In a prime mover adapted to be operated in an environment in which foreign ferrous material objects may be present, the prime mover having a stator, a pair of opposite end faces on the stator, a bore in the stator and intersecting with the opposite end faces, at least one pair of opposite pole winding means associated with the stator for creating a magnetic field upon the excitation of the at least one winding means pair, the at least one winding means pair having at least one grouping of end turns with the at least one grouping of end turns being disposed adjacent one of the opposite end faces so as to extend therebeyond, at least one non-ferrous material end plate disposed on the prime mover and spaced from the one opposite end face so as to be adjacent the at least one grouping of end turns, a rotatable shaft having a section rotatably received in the at least one end plate, a rotor mounted to the shaft so as to be conjointly rotatable therewith and disposed at least in part within the bore in magnetic coupling relation with the at least one winding means pair upon the excitation thereof, at least one means in the at least one end plate for the passage therethrough of ambient air into cooling relation with the at least one grouping of end turns and at least a part of the rotor; the improvement comprising a device adapted for obviating the ingress of the foreign ferrous material objects into the prime mover into deleterious magnetic attraction engagement with the at least one grouping of end turns or the rotor upon the excitation of the at least one winding means pair to create the magnetic field, said device including a shield 25, 71 of ferrous material mounted to the at least one end plate so as to provide generally thereacross a path for leakage flux of the magnetic field created between the at least one winding means pair upon the excitation thereof, an outer peripheral portion on said shield, another portion on said shield spaced from said outer peripheral portion so as to be disposed generally adjacent the shaft section in flux transfer relation therewith, at least another means between said outer peripheral portion and said another portion of said shield and arranged at least in part with the at least one passage means for the passage of the ambient air through the at least one passage means and said at least another passage means into the cooling relation with the at least one grouping of end turns and the at least part of the rotor, and said shield having a preselected cross-sectional area generally in the direction of said path for the leakage flux so that said shield remains unsaturated in response to the leakage flux in said path and said at least another passage means defines a null area with respect to the leakage flux in said path thereby to obviate magnetic attraction in response to the excitation of the least one winding means pair of the foreign ferrous material objects through the at least one passage means said at least another passage means into the prime mover.

Claim 15

A method of operating a prime mover in an environment in which foreign ferrous material objects may be present with the prime mover having at least one non-ferrous end plate and at least a pair of opposite pole winding means adapted upon energization to create a magnetic field therebetween, the method comprising the steps of: (a) conducting a part of the leakage flux of the magnetic field from one winding means of the at least winding means pair to the other thereof across the at least one end plate through a shielding device arranged on the at least one end plate in leakage flux transfer relation with the at least winding means pair and passing ambient air through at least one passage therefor in the shielding device past the at least one end plate into cooling relation with the at least winding means pair; and (b) maintaining the shielding device in an unsaturated condition during the conducting and passing step and insuring thereby that the at least one passage generally defines a null area with respect to the part of the leakage flux conducted by the shielding device in order to obviate the magnetic attraction of the foreign ferrous material objects through the at least one passage means into the prime mover.

Claim 16

A method of operating a prime mover in an environment in which foreign ferrous material objects may be present with the prime mover having at least one non-ferrous end plate and at least a pair of opposite pole winding means adapted upon energization to create a magnetic field therebetween, the method comprising the steps of: (a) conducting a part of the leakage flux of the magnetic field from one winding means of the at least winding means pair to the other thereof across the at least one end plate through a shielding device arranged on the at least one end plate in leakage flux transfer relation with the at least winding means pair and passing ambient air through at least one passage therefor in the shielding device past the at least one end plate into cooling relation with the at least winding means pair; and (b) maintaining the shielding device in an unsaturated condition during the conducting and passing step and insuring thereby that the at least one passage generally defines a null area with respect to the part of the leakage flux conducted by the shielding device in order to obviate the magnetic attraction of the foreign ferrous material objects through the at least one passage means into the prime mover.

Claim 17

A method of assembling a prime mover and operating it so as to prevent deleterious magnetic attraction of foreign ferrous material objects thereinto in response to the establishment of a magnetic field between at least a pair of opposite pole winding means of the prime mover upon the energization thereof and with the prime mover having at least one non-ferrous end plate, the method comprising: associating a device with the at least one end plate for conducting thereacross leakage flux of the magnetic field thereacross between the at least winding means pair upon the creation of the magnetic field and insuring that means in the device for the passage of ambient air therethrough past the at least one end plate into the prime mover into cooling relation with the at least winding means pair is unaffected by the conducted leakage flux so as to obviate the attraction through the passage means of the foreign ferrous material objects by providing the device with a preselected mass great enough so that the device remains unsaturated in response to the conducted leakage flux.

Claim 18

A method of assembling a prime mover and operating it so as to prevent deleterious magnetic attraction of foreign ferrous material objects thereinto in response to the establishment of a magnetic field between at least a pair of opposite pole winding means of the prime mover upon the energization thereof and with the prime mover having at least one non-ferrous end plate, the method comprising: associating a device with the at least one end plate for conducting thereacross leakage flux of the magnetic field thereacross between the at least winding means pair upon the creation of the magnetic field and insuring that means in the device for the passage of ambient air therethrough past the at least one end plate into the prime mover into cooling relation with the at least winding means pair is unaffected by the conducted leakage flux so as to obviate the attraction through the passage means of the foreign ferrous material objects by providing the device with a preselected mass great enough so that the device remains unsaturated in response to the conducted leakage flux.

Claim 24

A method for making a device adapted for conducting leakage flux emanating from a magnetic field between at least one pair of opposite pole winding means of a prime mover upon the energization thereof and assembling the device with respect to at least one means in a non-ferrous end plate of the prime mover for the passage of ambient air into the prime mover into cooling relation with at least the at least winding means pair, the method comprising the steps of: (a) forming the device so that it has a preselected mass great enough to insure the transmission of the leakage flux therethrough between the at least winding means pair without effecting leakage flux saturation of the device and providing through the device at least another passage means for the ambient air; (b) associating the device in an assembly position with respect to the end plate and arranging the at least another passage means at least in part in aligned relation with respect to the at least one passage means in the end plate; and (c) securing the device in its assembly position to the end plate.

Claim 25

A method for making a device adapted for conducting leakage flux emanating from a magnetic field between at least one pair of opposite pole winding means of a prime mover upon the energization thereof and assembling the device with respect to at least one means in a non-ferrous end plate of the prime mover for the passage of ambient air into the prime mover into cooling relation with at least the at least winding means pair, the method comprising the steps of: (a) forming the device so that it has a preselected mass great enough to insure the transmission of the leakage flux therethrough between the at least winding means pair without effecting leakage flux saturation of the device and providing through the device at least another passage means for the ambient air; (b) associating the device in an assembly position with respect to the end plate and arranging the at least another passage means at least in part in aligned relation with respect to the at least one passage means in the end plate; and (c) securing the device in its assembly position to the end plate.

Claim 33

A method of operating a prime mover in an environment in which foreign ferrous material objects may be present, the prime mover having at least a pair of opposite pole winding means adapted upon energization for establishing a magnetic field therebetween and the prime mover also having at least one generally non-ferrous end plate with at least one means therein for the passage of ambient air through the at least one end plate into cooling relation with at least the at least winding means pair, the method comprising: carrying at least a part of the leakage flux from the magnetic field between the at least winding means pair through a ferrous material shielding device arranged on the at least one non-ferrous material end plate and passing the ambient air into the cooling relation with at least the at least winding means pair through at least one passage in the shielding device arranged at least in part in ambient air passage communication with the at least one passage means in the at least one non-ferrous material end plate, the shielding device having a mass great enough to remain generally unsaturated in response to the leakage flux carried thereby so that the at least one passage in the shielding device defines a null area obviating magnetic attraction therethrough of the foreign ferrous material object into the prime mover.

Claim 34

A method of operating a prime mover in an environment in which foreign ferrous material objects may be present, the prime mover having at least a pair of opposite pole winding means adapted upon energization for establishing a magnetic field therebetween and the prime mover also having at least one generally non-ferrous end plate with at least one means therein for the passage of ambient air through the at least one end plate into cooling relation with at least the at least winding means pair, the method comprising: carrying at least a part of the leakage flux from the magnetic field between the at least winding means pair through a ferrous material shielding device arranged on the at least one non-ferrous material end plate and passing the ambient air into the cooling relation with at least the at least winding means pair through at least one passage in the shielding device arranged at least in part in ambient air passage communication with the at least one passage means in the at least one non-ferrous material end plate, the shielding device having a mass great enough to remain generally unsaturated in response to the leakage flux carried thereby so that the at least one passage in the shielding device defines a null area obviating magnetic attraction therethrough of the foreign ferrous material object into the prime mover.