Note: Descriptions are shown in the official language in which they were submitted.
21048~8
G- 1 12 6 9
INTERNAL COMBIJ~TION ENGINE
Technical Field
The invention pertains to internal
combustion engines of the type with a cylinder
block/crankcase and a cylinder head which are
connected together by bolts.
Backaround
In known internal combustion englnes, the
cylinder head is often attached to the cylinder
block/crankcase either by hexagonal bolts or by bolts
screwed into the cylinder block/crankcase where the
bolt heads or nuts lie above washers on a flat surface
of the cylinder head. In internal combu~tion engines
with four or more valves per cylinder and a relatively
small cylinder bore, however, this type of attachment
of the cylinder head to the cylinder block/crankcase
is often difficult. Especially in the case of valves
with cup tappets, there is not sufficient ~pace for
installing the support surfaces for the bolt heads or
nuts in the usual places. It is therefore necessary
to compromise with regard to the arrangement of the
cylinder head bolts and the valves or their gas inlet
and exhaust passages.
Such an internal combustion engine is
described in U.S. patent 4, 745, 892 issued May 24,
1988. In it the bolts in each case extend through a
bore in the cylinder head and are screwed into a
threaded bore in the cylinder block/crankcase. There, - -
differential screws with two threaded segments are
proposed. The use of differential screws, however,
requires an accurate matching of the threads of the
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two differential bolts so that uniform support of the
thread is guaranteed. For this purpose either extra
engineering costs are necessary or else one of the two
threads is cut in an axially displaceable threaded
bushing which is inserted, e.g. in the cylinder head
in a corresponding threading. The production of this
threaded bushing and its installation and adjustment
is, however, an additional expense. Another
disadvantage of an internal combustion engine of this
type also consists in the fact that in each case the
differential bolts must be accessible for tools from
the cylinder head top so that space must remain for
them. Therefore, the possibility of optional shaping
of the adjacent structural components such as camshaft
and its bearings, valve guides, valve lifting
elements, intake and exhaust ducts and water jacket
are limited.
Summary of the Invention -
The invention has the purpose of eliminating
the aforementioned drawbacks.
According to the invention this problem is
solved by designing the bolts connecting the cylinder
head to the cylinder-crank block as through bolts
emerging from the cylinder-crank block and screwed in
from below in threaded cores in the cylinder head.
When this is done the bolts forming the
through bolts on a contact face of the cylinder
block/crankcase can either be provided with a head or
with a threaded end and equipped with a nut screwed
down on them.
Advantageously the contact surface of the
cylinder block/crankcase is located on the crankshaft
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bearing caps and the bolts designed as through bolts
thus hold the crankshaft bearing caps on the bearing
blocks.
It is already known how to attach the
cylinder head to the cylinder block/crankcase with
through-going bolts which extend up to the crankshaft
bearing caps (DE 31 21 605), but here the through-
going bolts are inserted from the head side, i.e. from
above and are only guided up to the upper bearing
straps of the crankshaft and then screwed in there.
With this arrangement, no advantage can be achieved
over the conventional cylinder head bolts in the
configuration of the components lying closely together
on the cylinder head.
Brief~Drawin~ Description
An example of execution of the invention is
described in the following with reference to one
drawing. The drawing shows an internal combustion -
engine in a cutaway view.
Detailed Descrlption
A cylinder block 1 is seated on a crankcase
2 and together with it forms a cylinder
block/crankcase 3. The cylinder block/crankcase 3 is
closed at the top by a cylinder head 4. In the
cylinder block are located the cylinders 5 in which
pistons 6 slide in a tightly fitting manner and form
with the cylinder head 4 in each case the boundaries
of a combustion chamber 7. In the region of the
working path of the piston 6 the cylinder block 1 is
provided with a water jacket 8 for cooling. The
pistons 6 are connected by connecting rods 9 to a
crank=haft lo which i~ located in the crankca~e 2 and
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2la4sss
supported on crankshaft bearings 11. The crankshaft
bearings 11 in each case are firmly connected by a
bearing block 12 and a crankshaft bearing cap 13 to
the cylinder block/crankcase 3. The cylinder
block/crankcase 3 is closed at the bottom by an oil
pan, not shown. In the cylinder head 4 two camshafts
14 and 15 are mounted which act with cams 16 on cup
tappets 17 to actuate valves 18. A gas exchange
passage 19 runs to each of the valves 18. For each
combustion chamber 7 in the cylinder head 4 a vertical
shaft is provided for a spark plug or injection
element. Oil spaces 20 are necessary in order to be
able to introduce and remove the oil necessary for
lubricating and cooling the moving parts. Finally
ducts 21 are provided to carry coolant.
The cylinder head 4 is connected by bolts 22
to the cylinder block 1 which are screwed in to the
cylinder head from the cylinder block side with a
fitting 25 in relatively short threaded cores 23. The
threaded cores 23 can be installed without problem
below the camshafts 14, 15. The bolts 22 extend
through the cylinder block/crankcase 3 and are
supported on the crankshaft bearing caps 13 by a bolt
head or a screwed on nut 24. The bolts 22 can thus be
inserted as upright bolts into cylinder head 4. After
the cylinder head 4 is in place together with these
upright bolts on the cylinder block/crankcase 3 then
the nuts 24 are screwed onto a threaded end of the
bolt 22 designed as an upright bolt. The bolts 22 are
preferably designed as expansion screws and thus hold
the cylinder block/crankcase 3 consisting of the
cylinder block 1 and the crankcase 2, the crankshaft
210~898
bearing caps 13 lying on the bearing blocks 12 of the
crankcase 2, and the cylinder head 4, together at a
defined force.
A particular advantage of the invention is
that the cylinder head 4 can then be completely
assembled in advance even through, every cylinder 5,
four or more valves 18 are provided which can enclose
a valve angle between 280 and more than 40O with each
other in order to achieve optimal combustion chamber
; 10 shape as well as two camshafts 14, 15 for activating
the valves 18, and also room is required for the oil
spaces 20 as well as ducts 21 for the coolant. This
is possible, because for the attachment of the
cylinder head 4 room is no longer required as before
from above for accessibility to the cylinder head
bolts being inserted from above. Because precisely in
the areas required for this with the usual dimensions
of the components the camshafts lie above the
otherwise necessary cylinder head bolts. In an
internal combustion engine according to the present
invention the camshaft 14 can be finally mounted in
advance directly above the bolt~ 22 holding the
cylinder head 4 without the occurrence of problems in
assembly. The threaded cores 23 receiving the
threaded ends 25 of the bolts 22 find room below the
camshafts 14, 15 and no longer need be reachable from
above. The bolt pipes required for the cylinder head
bolts of the usual type which reach as far as the
upper region of the cylinder head and prevent the
optimal configuration of the gas exchange passages and
the valve activation elements are also no longer
necessary.
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The invention iæ also applicable to an
internal combustion engine with only one overhead
camshaft as well as to one with only two valves per
cylinder. Since other variations are possible, the
invention should be given the full scope permitted by
the language of the following claims.
