Robot arm for an industrial robot

A robot arm adapted for use as an industrial robot comprising a plurality of hollow arm members each having joint portions at opposite ends thereof and a center axis, means for rotatably connecting said arm members to each other at said joint portions;

• said arm members including an upper arm member, a lower arm member and at least one intermediate arm member therebetween;
• said intermediate arm member having an outer boundary at each of its joint portions, ends of said joint portions each including a joint face which is inclined at a certain inclination angle with respect to the center axis of an associated arm member, each joint portion having a joint axis disposed at a right angle to its associated joint face, the center axis intersecting the joint axes at opposite joint faces of the same arm member at points of the joint face provided with driving means for each adjacent joint portion;
• said driving means including an electric motor having a rotor fixed at a joint portion and a rotating shaft thereof being aligned with the associated joint axis, said driving means further including a stator of said electric motor fixed at another of the adjacent joint portions;
• and a plane through the joint faces on opposite ends of said intermediate arm member intersecting each other at a point located outward of each outer boundary of said intermediate arm member.