Internal-combustion engines – Particular piston and enclosing cylinder construction – Cylinder head
Reexamination Certificate
2002-03-12
2003-05-13
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Particular piston and enclosing cylinder construction
Cylinder head
Reexamination Certificate
active
06561153
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an internal combustion engine and more particularly to an improved spark plug mounting arrangement for the cylinder heads of such engine.
With many types of internal combustion engines and particularly those utilized for automotive application, the ignition system includes an individual coil that is associated with each spark plug of the engine. These individual coils are mounted on the upper end of the electrical terminal that connects the coil output to the spark plug. This presents a problem in servicing as may be best understood my reference to
FIG. 1
, which shows a typical prior art type of construction, utilized for this purpose.
As seen in this figure, an internal combustion engine, indicated generally by the reference numeral
21
has a cylinder head assembly, indicated generally by the reference numeral
22
. This cylinder head assembly
22
is comprised of a cylinder head
23
and a cam cover
24
that is affixed to the cylinder head
23
with a sealing gasket interposed there between (not shown). This defines a cam chamber
25
in which a valve actuating mechanism, shown partially and identified by the reference numeral
26
is positioned.
The cylinder head
23
has a lower surface in which combustion chamber recesses
27
are formed. The combustion chamber recesses
27
of the cylinder head defining the combustion chamber is formed with a tapped opening
28
so as to receive the threaded end of a spark plug
29
with its terminals projecting into the combustion chamber.
It will be seen that the upper end of the spark plug
29
extends into a tubular spark plug tube
31
which has its lower end sealingly engaged in a spark plug tube receiving pocket
32
of cylindrical configuration formed in a lower surface
33
of the cylinder head
23
. This tubular spark plug tube
31
extends upwardly and passes through an opening
34
formed in the cam cover
24
with a sealing grommet
35
being interposed there between.
The spark plug is fired by a coil
36
that is activated by an associated ignition system and terminal
37
that are inserted into the tubular spark plug tube
31
with the lower end of the terminal engaged with the terminal end of the spark plug
29
as shown in the cylinder to the right in FIG.
1
.
A problem in connection with servicing arises, however, when the placement of the engine
21
is such that one or more of the tubular spark plug tube
31
is disposed in an obstructed area. For example,
FIG. 1
shows a conventional brake booster
38
, which overlies the end cylinder of the engine and accordingly blocks the removal of the coil
36
and terminal
37
for servicing of the spark plug
29
.
In addition to the servicing problem, this type of construction also presents difficulty in engine assembly. That is, it is necessary when building the engine or when servicing the engine to place all of the tubular spark plug tube
31
in the cylinder head
23
and then attach the cam cover
24
while guiding the sealing grommets
35
around the periphery of the upwardly projecting tubular spark plug tube
31
. The greater number of cylinders, the more difficult it is to connect and assemble them.
It is, therefore, a principal object to this invention to provide an improved cylinder head structure of this general type, but one in which the spark plugs can be easily accessed for servicing without encountering the problems in connection with the prior art type of construction.
It is a further object to this invention to provide an improved spark plug receiving tube assembly for the cylinder head of an internal combustion engine that facilitates servicing and minimizes operational and assembly costs.
SUMMARY OF THE INVENTION
This invention is adapted to be embodied in a cylinder head assembly for an internal combustion engine that comprises a cylinder head and a cam cover. The cam cover is affixed to the cylinder head so as to define a cam chamber between an upper surface of the cylinder head and the interior of the cam cover. The cylinder head is formed with at least one spark plug receiving, threaded hole leading into a combustion chamber of the cylinder head. The cylinder head forms a spark plug tube attaching hole that is greater in diameter than and surrounds the at least one spark plug receiving, threaded hole. A spark plug tube inserting hole is formed in the cam cover and is aligned with the cylinder head spark plug tube attaching hole. A lower spark plug tube is sealingly affixed at one end thereof to the cylinder head spark plug tube attaching hole. An upper spark plug tube is sealing engaged at one end thereof to the cam cover spark plug tube attaching hole and is sealingly engaged at the other end thereof to the other end of the lower spark plug tube.
REFERENCES:
patent: 5535714 (1996-07-01), Aoyama et al.
patent: 5809968 (1998-09-01), Tsuchida
patent: 6209507 (2001-04-01), Sakamoto et al.
patent: 6279529 (2001-08-01), Komatsu et al.
Beutler Ernest A.
McMahon Marguerite
Yamaha Hatsudoki Kabushiki Kaisha
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