Abstract: An EGR valve includes: an inner housing including a flow passage; a valve element which opens and closes the flow passage; a valve shaft on which the valve element is provided; an outer housing in which the inner housing is assembled; and a drive unit which drives the valve shaft. The flow passage of the inner housing includes an inlet and an outlet. The outer housing includes an assembly hole and separate flow passages. When the inner housing is assembled in the assembly hole, the inlet and the outlet of the inner housing communicate with the separate flow passages of the outer housing; an inlet sealing member is provided between the inner housing and the outer housing to correspond to the periphery of the inlet; and an outlet sealing member is provided between the inner housing and the outer housing to correspond to the periphery of the outlet.

Abstract: Resistance spot welding includes a first process of performing energization by pressurizing two or more metal plates superposed by sandwiching a pair of electrode tips, and a second process of stopping energization in the first process and pressurizing two or more metal plates by a pair of electrode tips. The estimation method for the nugget diameter includes: a thickness estimation process of estimating the nugget thickness using the amount of expansion in the thickness direction of two or more metal plates in the first process and the electric resistance value between the pair of electrode tips in the first process; and a diameter estimation process of estimating the nugget diameter using the expansion amount and the electric resistance value when the nugget is estimated to have reached the interface between two adjacent metal plates using the respective thicknesses of the two or more metal plates and the estimated nugget thickness.

Abstract: An EGR valve includes: an inner housing including a flow passage; a valve element which opens and closes the flow passage; a valve shaft on which the valve element is provided; an outer housing in which the inner housing is assembled; and a drive unit which drives the valve shaft. The flow passage of the inner housing includes an inlet and an outlet. The outer housing includes an assembly hole and separate flow passages. When the inner housing is assembled in the assembly hole, the inlet and the outlet of the inner housing communicate with the separate flow passages of the outer housing; an inlet sealing member is provided between the inner housing and the outer housing to correspond to the periphery of the inlet; and an outlet sealing member is provided between the inner housing and the outer housing to correspond to the periphery of the outlet.