Internal-combustion engines – Particular piston and enclosing cylinder construction – Cylinder head
Reexamination Certificate
2001-02-23
2002-11-05
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Particular piston and enclosing cylinder construction
Cylinder head
C029S402170
Reexamination Certificate
active
06474285
ABSTRACT:
BACKGROUND OF THE INVENTION
Inquires have increased recently for repairing a damaged spark plug hole in an aluminum cylinder head of a vehicle engine. Most of the engines experiencing the problem have more than 80,000 miles on the vehicle. When the spark plug is removed in these high mileage engines for a tune-up the threads in the head may strip out as the plug is removed. This is due to carbon built up on the spark-plug threads.
In the past, there was no way of repairing the damaged spark plug hole. Therefore, the cylinder head had to be replaced if the spark plug hole was damaged. The cost of labor and total materials used for the head replacement can be more than two thousand dollars. It is very expensive and time consuming.
The present invention is directed to overcoming one or more of the above problems.
SUMMARY OF THE INVENTION
In accordance with the invention a new method is provided using new tools for repairing a damaged spark plug hole in a cylinder head of a vehicle engine. More specially, the repairing method uses a set of tools that would repair the damaged spark plug hole while the cylinder head having the damaged spark hole remains in the vehicle.
Additionally, a new structure of a spark plug hole is provided that is harder to damage and can be used for much longer time compared with the original spark plug hole.
An exemplary embodiment of the invention achieves the foregoing in a method including first drilling the damaged spark plug hole using a drill bit to provide a drilled hole. A stopper is used to limit the depth of the drill to prevent damaging a piston in a cylinder of the vehicle engine. Secondly, the drilled spark plug hole is tapped to provide a threaded hole with the stopper limiting the depth of the thread. Thirdly, a steel insert is threaded into the threaded hole with the stopper guiding the insert to a required depth. The insert is cylindrical having an outer threaded surface and an inner surface having a threaded portion. Finally, the insert is seated to make a spark plug seat.
In accordance with one aspect of the invention, a tapping and threading tool is used for tapping the drilled hole and threading the insert into the threaded hole.
In accordance with another aspect of the invention, a seating tool is used for seating the spark plug hole.
As a result of the foregoing repairing method, the damaged spark plug hole is repaired using much less labor hours and materials compared with the replacement of the cylinder head. The amount of money saved by this method compared with the head replacement is substantial.
The resulting repaired hole having a steel insert is stronger and more durable than the original spark plug hole in an aluminum cylinder head.
Other features and advantages will become apparent from the following specification taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 2795221 (1957-06-01), Braendel
patent: 3187729 (1965-06-01), Morrison
patent: 3449816 (1969-06-01), Swick et al.
patent: 3683873 (1972-08-01), Tarter
patent: 3694838 (1972-10-01), Runton
patent: 3750259 (1973-08-01), Timmons
patent: 3847499 (1974-11-01), Heyworth et al.
patent: 3864806 (1975-02-01), Hanson et al.
patent: 5842924 (1998-12-01), Manos et al.
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