Bearing insert for supporting rotatable shafts, method of repair, and related broach tool

Abstract

A cam shaft bearing insert is provided for use in a cam shaft support bearing for operably supporting a cam shaft in an internal combustion engine. The engine includes a cylinder head with bearing support towers that operably support journals on the cam shaft at multiple aligned bearing locations. Each bearing support tower has an oil port for passing oil to the associated journal. The bearing insert further has a thin-walled cylindrical sleeve formed from thin flat stock into a cylindrical tubular shape that is adapted to fit into one of the bearing support structures and form a bearing surface suitable for supporting the cam shaft. The sleeve has an outer surface with an outwardly deformed area configured to non-rotatably engage the one bearing support structure and has an aperture therein so that, when the aperture is aligned with the oil port of the one bearing support structure, oil can pass from the oil port to the associated bearing location. The sleeve includes a longitudinal slit allowing the sleeve to flex outwardly to slip onto a journal of the cam shaft and then flex inwardly into one of the bearing support structures of the cylinder head. A broaching tool is provided that is adapted to be linearly pulled through the aligned bearing locations to reform the bearing support structures in preparation for receiving one of the bearing inserts. A method of repair includes enlarging at least one cam shaft support bearing to an oversized condition, such as by using the broach, repairing the oversized cam shaft support bearing by filling voids and galled areas with a thermal setting polymer, as needed, positioning a bearing insert on the cam shaft, and positioning the cam shaft including the bearing insert in the cam shaft support bearing with the cam shaft being rotatably supported in the bearing insert and the bearing insert being secured to the oversized cam shaft support bearing.