Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CYLI~:)E~ HEAD FOR AN INT53RNAL-COMBUSTION ENGINE
The invention relates to a cylinder head for an
internal combustion engine o~ the type having a
hemispherically or dome-shaped combustion chamber with intake
and exhaust valves arranged approximately radially to its
surface. The valves are operable by sheet metal rocker arms
actuated by tappets engaged directly with the cams of an
overhead camshaft. The camshaft is arranged symetrically
between the intake and exhaust valve trains. Bridges span the
camshaft adjacent to the camshaft bearing webs, and are formed
from the cylinder head projections or bosses that accommodate
the valve stem guides, the rocker arm stud mounting holes, and
the tappet guides.
A cylinder head of the type broadly described above
is shown and described in U.S. Patent 3,164,143. In the
patent, the area of the cylinder head extending beneath the
camshaft is of a tank-shaped construction. This permits
excess lubricating oil that runs off from the tappet guides,
which generally are supplied with an excess of lubricating oil
under pressure, to accumulate, forming a lubricating oil sump
for the camshaft. The usual drainage orifices from this
lubricating oil sump are located to provide an oil level build
up that will assure the cam surfaces of the camshaft being
wetted by the dip lubrication method. Lubrication of the
rocker arm bearing pieces, therefore, in the patent is
intended to be achieved by the splash oil occurring in the
valve gear space.
In an internal combustion engine, if hydraulic valve
tappets are adopted, which automatically compensate for play
in the valve gear, then it is important to control the amount
of air that is added to the lubricating oil delivered by the
oil pump to the engine.
The lubrication of the valve gear of an internal
combustion engine by pressure lubrication and dip and splash
lubrication hitherto practiced leads inevitably to higher
:~;
proportions of air in the lubricating oil, This results
either in an impairment of effectiveness of the hydraulic
valve tappets or, alternatively, the adoption of onerous
measures to calm the lubricating oil~
In accordance with the present invention, there
is provided a cylinder head for an internal combustion
engine having a dome-shaped combustion chamber with intake
and exhaust valves arranged approximately radial to the
surface of the chamber and symmetrically located on opposite
sides of a single overhead camshaft for individual actua-
tion by one end of a rocker arm that is pivotally mounted
to the head by a stud, the rocker arm being operably engaged
at its opposite end by a tappet movable by the camshaft,
and bridge members spanning the camshaft and providing
mounting bores for the studs, and providing tappet guides
slidably accommodating the tappets therein, the tappet
guides receiving lubricating oil therein that is exuded
from the guides during movement of the tappet by the camshaft,
characterized byt an oil collecting basin adjacent a tappet
guide fbr collecting oil exuded thererom, the basin having
a discharge hole therein vertically aligned with a portion
of a cam on the camshaft so as to drip oil on the cam
to lubricate the cam.
The improved construction of a cylinder head
Of the present invention eliminates the hitherto customar~
dip and splash lubrication of parts of the valve gear
of the internal combustion engine. The collection of
the lubricating oil exuding from the tappet guides and
discharge thereof through oil drainage holes aligned with
portions of the corresponding cams of the camshaft, enables
very reliable lubrication of the camshaft to be achieved
and furthermore reduces to a minimum the inclusion of
air in the lubricating oil.
As a modification, spout-like inserts may be
3S pressed into the oil drainage holes, the inserts consisting
of thin walled tubes so that the ends constitute in effect
sharp edges to ensure an aimed dripping of the lubricating
oil onto the corresponding cams of the camshaft.
Other features include lubricating oil channels
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connected from the tappet guides to those sections of
the rocker arm stud mounting bores located above the screw-
threads~ radial lubricating oil grooves on the rocker
arm fulcrum bearing surface loaded by the nut, and lubrica-
tion of the rocker arm lower bearing surface while avoidingoil splashes that cause air inclusions. Also, the area
in the cylinder head that lies beneath the camshaft communi-
cates by lubricating oil drainage orifices with oil return
channelsr and~ therefore, eliminates the need for a camshaft
lubricating oil sump.
Other features and advantages of the invention
will become more apparent upon reference to the succeeding,
detailed description thereof,, and to the drawings illustra-
ting the preferred embodiments thereof; wherein,
Figure 1 is a plan view of an internal combustion
engine cylinder head embodying the invention,
Figure 2 is a vertical cross-sectional view made
along the line II-II in Figure 1,
Figure 3 is an enlarged cross-sectional view
Of a detail of Figure 2,
Figure 3a is a cross-se~tional view of a modifica-
tion of the Figure 2 showingL and
Figure 4 is a vertical cross-sectional view made
along the line III-III in Figure 1.
Referring to the drawings, Figures 1 and/or 2
illustrate a cylinder head 1 for an internal combustion
engine that is formed with a hemispherically or dome-
shaped combustion chamber 2, mutually communicating cooling
medium spaces 3, intake and exhaust passages (only partly
shown) located between the cooling spaces and controlled
by intake and exhaust valves 4 and 5, respectively, and
a spark plug bore accommodating a spark plug 6.
An overhead mounted camshaft 7 extends parallel
to the longitudinal direction or axis of the internal
combustion engine and is rotatably mounted in a plurality
of camshaft bearing webs 8 (Figure 1), Adjacent to the
camshaft bearing webs 8 are formed bridges 15 that span
the camshaft 7 and extend from the bosses or projections
that accommodate the valve stem guides 9 and 10, the rocker
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: 3a
arm fulcrum mounting stud bores 11 and 12, and the tappet
guldes 13 and 14.
Formed in the bridges 15 adjacent each of the
tappet guides 13 and 14 are oil collector basins 16 and
17. The latter collect the excess lubricating oil that
normally is exuded from the tappet guides 13 and 14 during
reciprocation of the tappets. The tappets are supplied
with oil from an oil pump, not shown., in a known manner.
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This oil from the tappet guides is discharged through oil
discharge holes 18 (Figure 3) formed in each of the basins and
vertically aligned with portions of the corresponding cams on
the camshaft 7. Pressed into the oil discharge bores 18 may
be oil passage inserts 19 that consist of a thin sheet metal
tube or the like, the ends 22 of which project beyond the
bottom wall of the bridge member. miS ensures an aimed
dripping of the lubricating oil onto the corresponding cams of
the camshaft 7.
The oil passage inserts 19 in this case may be
constructed as a polygonal tube, for example, and have flared
or funnel-like conical portions 21 at their upper ends and
drip lip type edges 22 at their lower ends.
Figures 1 and 2 show that lubricating oil exuding
from the top of the tappet guide bore 14 will run down the
outsides of the cylinder head boss and accumulate in the oil
collector basins 16 and 17. From there, it can drip through
the oil passage inserts 19 onto the cams of the revolving
camshaft 7. It will also be seen that the open area 23
extending beneath the camshaft 7 returns the lubricating oil
in this area to the crankcase (not shown) through connecting
lubricating oil return channels 24 and 24'.
An alternate construction of the invention is shown
in Figure 3a in which a molded drip lip 18' is integrally
shaped in the casting of the cylinder head in a manner to
intersect the adjacent oil discharge bore 18 and thus form a
drip edge. It is likewise possible to produce the oil passage
inserts 19' (Figure 3) from a plastics material, in which case
the inserts can be prevented from accidental falling out of or
being displaced from the oil discharge bores 18 by one or more
flexible retaining lips 20'.
Figure 4 illustrates a further feature of a cylinder
head constructed according to the invention. In this case,
the bore communicates with a lubricating oil channel 25
that connects to the screw-thread portion of the bore 26 in
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which is mounted the rocker arm fulcrum supporting stud 27.
The stud 27 screwed into bore 11 tensions, through a nut 28,
the semi-cylindrical rocker arm bearing piece or fulcrum 29
against a step or offset 30 of the bore. Biased or forced
against the rocker arm bearing piece 29 is a sheet metal
rocker arm 31, one end of which is engaged by a hydraulic
tappet 32, and the other end bearing against the stem of the
valve 4. The lubrication of the semi-cylindrical surfaces
between the rocker arm fulcrum 29 and the corresponding
bushing in the sheet metal rocker arm 31 is particularly
essential and is ensured according to the invention by radial
lubricating oil yrooves 33 in the plane surface of the rocker
arm fulcrum 29 at the point loaded by the nut 28. Due to the
loading of the bore 11 of the stud 27 with lubricating oil
under pressure, lubricating oil can cIimb up the central bore
of the rocker arm bearing piece 29 and be guided at the nut 28
through the radial lubricating oil grooves 33 to the lateral
portions of the rocker arm 31, from where it passes onto the
bushing surfaces of the rocker arm 31.
From the foregoing, it will be seen that components
of the valve gear of the internal combustion engine are
adequately lubricated by specific measures so that the
hitherto customary dip lubrication or oil splash lubrication
method of lubrication can be abandoned, which will result in
lubricating oil in the entire lubricating oil circuit of the
internal combustion engine being kept as free as possible from
air inclusions.
While the invention has been shown and described in
its preferred embodiments, it will be clear to those skilled
in the arts to which it pertains that many changes and
modifications may be made thereto without departing from the
scope of the invention.
