Patent attributes
In a fluid transmission device, a male fitting surface of a periphery of a diameter-expanded portion of a pump shell is fitted to a female fitting surface of an inner circumference of a peripheral wall portion of a cylindrical transmission cover, and a fillet weld being is formed between an end surface of the peripheral wall portion and a peripheral surface of the diameter-expanded portion along an entire circumference, thereby connecting together the pump shell and the transmission cover. An annular recess is formed in an inner circumferential surface of the peripheral wall portion to adjoin the female fitting surface on the side opposite from the fillet weld. A portion of the transmission cover corresponding to the recess constitutes an annular thin-walled portion which has a thickness smaller than the portions of the transmission cover along the opposite sides of the annular thin wall portion. Therefore, even if the diameters of the pump shell and the transmission cover are increased, the durability of the pump shell and the transmission cover can be improved by alleviating excessive stress concentration on the fillet weld between the pump shell and the transmission cover.
