Patent ID: 7368843

Claim:
A power tool comprising: a commutator motor comprising: a stator comprising a stator yoke having a tubular shape and extending in an axial direction and having an inner peripheral surface and an outer peripheral surface, and a permanent magnet fixed to the inner peripheral surface of the stator yoke for providing a field magnetic pole in the stator, wherein the inner peripheral surface has a circular shape, and wherein the outer peripheral surface has a rounded portion and a linear portion; and an armature rotatably disposed within the stator, wherein the stator yoke comprises a plurality of plate-like annular bodies having iron parts which are stacked on each other coaxially in the axial direction of the stator yoke, and wherein each of the plurality of plate-like annular bodies has a convex portion and a concave portion to provide a caulking portion, so that plate-like annular bodies adjacent to each other in the stacked direction are fixedly connected to each other by caulking upon engagement of the convex portion with the concave portion; a housing accommodating therein the commutator motor; and, a power source that supplies an electric power to the commutator motor; wherein the stator yoke has a first part defined between the rounded portion and the inner peripheral surface and a second part defined between the linear portion and the inner peripheral surface, a cross-sectional area of a field magnetic path, when viewing in a radial direction of the stator yoke at the first part, being greater than that at the second part, and wherein the caulking portion is positioned at the first part and between the outer peripheral surface and the inner peripheral surface of the stator yoke.