Patent ID: 7761975

Claim:
A method of making a stator of an electric machine, said method comprising: a) making individual generally strip-shaped laminas ( 15 ) for the stator; b) stacking the individual laminas ( 15 ) to form a stator core ( 13 ) with a yoke ( 26 ) having a yoke height (H yoke ), so that one side of the stator core is provided with grooves ( 18 ) extending through the core; c) producing a subassembly by inserting a stator winding ( 17 ) into the grooves ( 18 ) of the stator core ( 13 ) formed in step b); d) bending the subassembly in a circular fashion to form a cylindrical cavity, so that the grooves ( 18 ) end in the cavity; and e) in order to keep the subassembly in a configuration with the cylindrical cavity, connecting at least two ends ( 23 ) of the stator core ( 13 ) to each other by means of a welding seam ( 20 ); f) selecting a depth of the welding seam to give the welding seam a sufficient strength to absorb tensile forces occurring in the welding seam, but at the same time not to exert too excessive a negative influence on magnetic properties at a welding point due to structural changes occurring in the yoke, said selecting including selecting a welding seam depth (T S ) of the welding seam ( 20 ) as a function of the yoke height (H yoke ) and a tolerance value (ΔT S ) in accordance with the following formula (I): T S =0.5 mm*( H yoke /mm−1)±Δ T S (I); and selecting the welding seam depth (T S ) of the welding seam ( 20 ) to be not less than a minimum value (T Smin ) and said minimum value (T Smin ) to be dependent on the yoke height (H yoke ) and to be described by the following formula (II): T Smin ={ 3/40}*H Yoke .