Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
1999-04-29
2001-04-03
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
C123S090600
Reexamination Certificate
active
06209509
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to bearing inserts for operably supporting a rotatable shaft, such as a cam shaft in an internal combustion engine, and further relates to a method for repairing spaced-apart bearing supports to receive the bearing inserts, and still further relates to a broaching tool for use in the method.
Modern internal combustion engines for passenger vehicles typically include a cylinder head and a cam shaft rotatably supported at journals by the cylinder head at multiple aligned bearing locations. The cylinder heads include a bearing support structure (sometimes called “bearing housings”) at each of the bearing locations. An oil port is included in each bearing support structure for passing oil to journals on the cam shaft. As engines age, the bearing surfaces on the cylinder head and the journals on the cam shaft wear, such that these bearing locations sometimes need to be rebuilt. In extreme cases, galling and material deformation may occur, causing the cam shaft to roughly rotate or even freeze up on the cylinder head. It is known to repair these bearing locations by welding on the cylinder head to reapply material to the support structure, and thereafter to machine away excess material to reform the bearing surfaces. It is also known to simply machine away material on the cylinder head to form an oversized bearing surface. A problem is that accurate alignment of the bearing locations along a cam shaft is very important so that the cam shaft is properly positioned for rotation without stress, and so that the intake and exhaust valves of the internal combustion engine work properly. Set up for good alignment to recut the bearing locations is expensive and time consuming and can easily be done wrong. Further, the tools for cutting and machining the bearing locations can be expensive. Also, a plurality of different tools is required for each different bearing size, such that it requires significant capital investment for a repair shop. There are also the frustrations of not having (or not being able to find) the right size cutting tool for a particular size bearing.
It is known to cutaway the bearing support structure and to locate a whole new massive outer bearing in the cylinder head to support the cam shaft. Further, it is known to purchase new replacement cam shafts having particular sized cam shaft bearing surfaces. However, it is undesirable to cutaway substantial material from the cylinder head of modern engines since this can affect their strength, operation, and heat flow in the cylinder head in adverse ways. Further, removal of large amounts of material can lead to mistakes that totally destroy cylinder heads.
Notably, inserts have been used on valve guides for supporting linear movement of intake and exhaust valves on internal combustion engines for many years. For example, see U.S. Pat. Nos. 4,768,479 and 5,249,555. However, despite this type of engine repair for several years, no one has, to the inventor's knowledge, ever conceived of using thin-walled inserts in cam shaft bearings because different problems are presented. One such problem is that existing cam shaft constructions require that oil be injected from a side of the cam shaft bearing area so that oil reaches and lubricates the journals of the cam shaft. Further, it is difficult to retain a thin-walled insert in a cam shaft bearing arrangement due to the torsional forces on a cam shaft bearing, both in terms of preventing rotation of the insert and also preventing longitudinal creeping of the insert during use.
Accordingly, there is a need for a reliable bearing insert and a related method and tools that solve the aforementioned problems and that have the aforementioned advantages.
SUMMARY OF THE INVENTION
In one aspect, the present invention includes a cam shaft bearing insert for use in an internal combustion engine, where the engine includes a cylinder head and a cam shaft rotatably supported by the cylinder head at multiple aligned bearing locations. The cylinder head includes a bearing support structure at each of the bearing locations and has an oil port in each bearing support structure for passing oil to the associated bearing location. The cam shaft bearing insert includes a thin-walled cylindrical sleeve formed from thin flat stock into a cylindrical tubular shape that is adapted to fit into a selected one of the bearing support structures and form a bearing suitable for operably engaging and supporting the cam shaft. The sleeve has an outer surface shaped 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.
In another aspect, the present invention includes a bearing insert for use in an internal combustion engine, where the engine includes a cylinder head and a cam shaft rotatably supported by the cylinder head at multiple aligned bearing locations. The cylinder head includes a bearing support structure at each of the bearing locations. The cam shaft bearing insert includes 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 suitable for operably engaging and supporting the cam shaft. The sleeve has a deformable wall that, as installed, includes a cylindrically shaped major section and an outwardly formed minor section, with the outwardly formed minor section being configured to non-rotatably engage the one bearing support structure.
In another aspect, the present invention includes an internal combustion engine including a cylinder head and a cam shaft rotatably supported by the cylinder head at multiple aligned bearing locations. The cylinder head includes a bearing support structure at each of the bearing locations. The internal combustion engine also includes a resilient cylindrical sleeve positioned in one of the bearing locations and rotatably engaging the cam shaft. The sleeve is formed from thin flat stock into a cylindrical tube with a longitudinal slit and is made from material suitable to form a durable bearing for the cam shaft, but further is resilient so that the sleeve can flex to open up the slit, allowing the sleeve to slip onto the cam shaft at a selected one of the bearing locations, and to then reversely flex to fit into a selected one of the bearing support structures.
In yet another aspect, the present invention includes a broaching apparatus for use in a structural body having spaced-apart bearing supports with aligned holes defining an axis. The broaching apparatus includes an elongated broach having a longitudinally extending hole extending from end to end of the broach and having first threads formed along at least a portion of the longitudinally extending hole. The broach has a lead section, a cutting section, and a tail section. The cutting section is configured to enlarge the aligned holes from a smaller first diameter to a larger second diameter, and the lead and tail sections are configured to guide the broaching tool linearly through the aligned holes while maintaining accurate alignment with the aligned holes. The broaching apparatus further includes a motivating device including a broach puller and a holder rotatably receiving the broach puller. The broach puller has a shaft that extends through the holder with second threads on one end configured to mateably engage the first threads. The broach puller further has a configured end opposite the one end that is shaped to be engaged and rotatably driven by a hand tool. The holder includes a first end section rotatably abutting the configured end of the broach puller and a second end section configured to abut the structural body. Thus, the aligned holes in the structural body can be broached by pulling the elongated broach through the aligned holes by rotating the broach puller.
In another aspect, the present invention includes a cylinder head f
Kammeraad James A.
Kamphuis Dwain L.
Knowles, II Thomas W.
Argenbright Tony M.
Benton Jason
K-Line Industries, Inc.
Price Heneveld Cooper DeWitt & Litton
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