Torque converter impeller including impeller shell having thinned section

Abstract

An impeller for a torque converter is provided. The impeller includes an impeller shell including an inner circumference, an outer circumference and a radial extension extending radially outward from the inner circumference. The radial extension includes an axially extending groove formed therein. The impeller also includes an impeller hub welded to the impeller shell by a weld. The weld is radially inside of the axially extending groove. The axially extending groove is 5 to 10 millimeters from the weld. A method of forming an impeller for a torque converter is also provided.

What is claimed is: 
     
         1 . An impeller for a torque converter comprising:
 an impeller shell including an inner circumference, an outer circumference and a radial extension extending radially outward from the inner circumference, the radial extension including an axially extending groove formed therein; and   an impeller hub welded to the impeller shell by a weld, the weld being radially inside of the axially extending groove, the axially extending groove being 5 to 10 millimeters from the weld.   
     
     
         2 . The impeller as recited in  claim 1  wherein the radial extension includes a flat inner radial portion, the weld being formed on the flat inner radial portion, the radial extension protruding slightly axially inward to form an intermediate portion radially outside of the flat inner radial portion, the axially extending groove being formed in the intermediate portion. 
     
     
         3 . The impeller as recited in  claim 1  wherein the axially extending groove has a curved surface, the curved surface having a radius of curvature of at least 5 millimeters. 
     
     
         4 . The impeller as recited in  claim 1  wherein the axially extending groove is formed as a ring shaped groove extending circumferentially around the inner circumference. 
     
     
         5 . The impeller as recited in  claim 1  wherein the axially extending groove is formed in a back surface of the impeller shell, the impeller shell including a machined portion on a front surface of the radial extension opposite the axially extending groove. 
     
     
         6 . The impeller as recited in  claim 5  wherein the radial extension includes a flat inner radial portion, the weld being formed on the flat inner radial portion, the radial extension protruding slightly axially inward to form an intermediate portion radially outside of the flat inner radial portion, the axially extending groove and the machined portion being formed in the intermediate portion. 
     
     
         7 . The impeller as recited in  claim 5  wherein the machined portion is thinner than a remainder of the radial extension. 
     
     
         8 . The impeller as recited in  claim 6  wherein the machined portion is formed as a ring shaped flat surface. 
     
     
         9 . The impeller as recited in claim I further comprising impeller blades, the impeller shell including a rounded portion radially outside of the radial extension, the rounded portion supported the impeller blades. 
     
     
         10 . The impeller as recited in  claim 9  wherein the impeller shell includes an axial extension radially outside of the rounded portion for connected to a torque converter front cover, the axial extension defining the outer circumference. 
     
     
         11 . A torque converter comprising the impeller as recited in  claim 1 . 
     
     
         12 . A method of forming an impeller for a torque converter comprising:
 providing an impeller shell including an inner circumference, an outer circumference and a radial extension extending radially outward from the inner circumference;   forming an axially extending groove in the radial extension; and   welding an impeller hub to the impeller shell so as to form a weld on a back surface of the radial extension, the weld being radially inside of the axially extending groove, the axially extending groove being 5 to 10 millimeters from the weld.   
     
     
         13 . The method as recited in  claim 12  wherein the radial extension includes a flat inner radial portion, the weld being formed on the flat inner radial portion, the radial extension protruding slightly axially inward to form an intermediate portion radially outside of the flat inner radial portion, the axially extending groove being formed in the intermediate portion. 
     
     
         14 . The method as recited in  claim 12  wherein the forming the axially extending groove includes machining the axially extending groove into the radial extension. 
     
     
         15 . The method as recited in  claim 12  wherein the forming the axially extending groove includes stamping the axially extending groove into the radial extension. 
     
     
         16 . The method as recited in  claim 12  wherein the axially extending groove is formed in a back surface of the impeller shell, the method further including machining a front surface of the radial extension opposite the axially extending groove. 
     
     
         17 . The method as recited in  claim 16  wherein the radial extension includes a flat inner radial portion, the weld being formed on the flat inner radial portion, the radial extension protruding slightly axially inward to form an intermediate portion radially outside of the flat inner radial portion, the axially extending groove being formed in a back surface of the intermediate portion, the machining including machining a front surface of the intermediate portion. 
     
     
         18 . The method as recited in  claim 16  wherein after the forming the axially extending groove and machining the front surface, the radial extension has a thickness of at least 1.7 millimeters at the axially extending groove. 
     
     
         19 . The method as recited in  claim 12  wherein the axially extending groove has a curved surface, the curved surface having a radius of curvature of at least 5 millimeters. 
     
     
         20 . The method as recited in  claim 12  wherein the axially extending groove is formed as a ring shaped groove extending circumferentially around the inner circumference.