Supporting structure for slow speed large diameter electrical machines

An arrangement for mounting a generally rotationally symmetrical component of a rotary electrical machine of the vertical axis type, comprising:

• an outer ring, said outer ring being rigid and fixedly secured;
• a first inner ring arranged concentrically within the outer ring, said first inner ring supporting a rotor of said rotary electrical machine;
• means for interconnecting said outer ring with said first inner ring including a plurality of rigid arms, each of the plurality of rigid arms having a first and a second end, the first end of each of the plurality of rigid arms being connected at a first respective junction point to the outer ring and the second end of each of the plurality of rigid arms being connected at a second respective junction point to the first inner ring, each of said plurality of the rigid arms defining a first acute angle with the first inner ring, which first acute angle is greater than a second acute angle formed by a line tangent to the first inner ring at the second respective junction point, with all of the rigid arms being oriented similarly in the same rotational sense;
• and
• a plurality of tie bars, each of said tie bars joining together a pair of adjacent rigid arms at a pair of adjacent first respective junction points on the outer ring.

An electrical machine of vertical construction comprising:

• a stator;
• a rotor;
• an outer ring foundation structure surrounding the stator;
• upper guide bearing means for supporting the rotor;
• lower thrust bearing means for further supporting the rotor;
• both bearing means together include central bodies forming a concentric inner ring structure and a plurality of circumferentially extending and uniformly distributed spoke-like arms, the spoke-like arms being located intermediate said inner ring structure and said outer ring foundation structure;
• means for joining opposite ends of said arms to said inner and outer ring structures with respective axes of said arms forming identical acute angles with radial lines extending respectively from the common center of said inner ring structure and said outer ring foundation structure through corresponding joints which join outer ends of said arms with said outer ring foundation structure;
• the axes of said arms also forming identical acute angles with lines tangent to a circle at corresponding joints with the inner ring structure;
• said arms being inflexible over their whole effective length in the longitudinal direction corresponding to the applied load;
• and
• all of said arms being inclined in the same rotational sense so as to accomodate torsional stresses imposed upon said inner ring structure caused by thermally induced expansion thereof.