Note: Descriptions are shown in the official language in which they were submitted.
1062568
This invention relates to units of structure for internal
combustion engines, and in particular to regions of the engine
structure that will be heated in use to such high temperatures
that they require direct cooling. One typical application of the
invention is thus to certain regions of the cylinder head above
the surface directly exposed to the cylinder firing zonesO
It is customary to cool the cylinder blocks and heads of the
internal combustion engines, especially diesel engines, by means
of massive cooling water jackets surrounding the block and extensive
water cooling passages formed within both the head and the block.
Proposals have recently been made to do away entirely with the
customary jackets and to confine the passages to those regions of
the structure surrounding the cylinder that are most in danger of
overheating when in use. It has been found that other parts which
normally run at unnecessarily low temperatures - due to the massive
cooling provided by the normal jackets - are then adequately cooled
by lateral flow of heat through the walls surrounding the cylinder.
In many diesel engines, only those regions of the cylinder head
close to the injection nozzles, the valve guides and exhaust valve
seats, and the valve bridge require direct cooling; those regions
of the cylinder bore walls which lie closer to the cylinder head
also need direct cooling.
Although cylinder blocks and heads can be mass-produced with
restricted water passages around the danger zones to provide the
~k
106Z5~8
localised cooling just described, the machining of the passageways naturally
adds to the cost of the units. Another consideration is that although the
arrangements described have proved effective in controlling temperatures satis-
factorily while removing less heat than normal, the control they provide over
the heat removal process is far from complete. ~ne aspect of this is that the
supply and return passages, as distinct from the local cooling passages proper,
extract heat from regions which it is not desired to cool directly. Yet another
consideration is that it is sometimes difficult to match the shape of the cool-
ing passages proper with the parts they are to cool directly; for instance it
is often easiest to machine an annular passage but if this is applied to the
structure around a fuel injection nozzle or an exhaust valve seat, where the
hot zone usually lies mostly to one side of the nozzle or seat rather than the
other, the annulus will extend to the other, cooler side also and will remove
heat unnecessarily from that side also.
The present invention provides scope for achieving a more accurate
register between a positive cooling system and the regions requiring direct
cooling.
According to the present invention there is provided a structural
unit for an internal combustion engine comprising:- a deck defining a cylinder
cover having an extending surface and a region within said surface less in
area than said extending surface, said region having a sub-surface that is
heated in use so as to require direct cooling, to prevent over-heating of said
region; a heat-conducting structure; heat-conducting connection means between
said deck region and said heat-conducting structure; and fluid-flow cooling
means associated with said heat-conducting structure, whereby to remove heat
conducted to it through said heat-conducting connection means from said region
of said unit, and in which the section through said connection means at the
location between said connection means and said deck matches in shape and
-~ ~ -2-
106Z568
registers with said region Tequiring direct cooling to conduct heat from said
region to said heat conducting structure, said region being under substantial
influence from no other fluid flow cooling meansJ and said fluid flow cooling
means providing only minimum cooling of said heat-conducting structure so as
to prevent over-heating of said region.
The invention will now be described, by way of example, with refer-
ence to the accompanying drawings in which:-
-2a-
:.,,: ,
106Z56#
Figure 1 is a transverse cross-section of a cylinder head of a
multi-cylinder four-stroke diesel engine, on the line F-F in
Figure 2;
Figure 2 is a section of the line B-B in Figure 1;
Figure 3 is a section on the line C-C in Figure 1;
Figure 4 is a section on the line A-A in Figure 5;
Figure 5 is a section on the line D-D in Figure 4, and
Figure 6 is a section on the line E-E in Figure 4.
Figures 1 to 3 show an example of the engine using a liquid,
namely water~ as coolant. A part of the lower surface 8' of the
lower deck 8 of the cylinder head appertaining to each cylinder is
exposed in use to the combustion zone of that cylinderO According
to the invention heat is conducted away from certain regions of the
upper surface 8" by a cooled heat-conducting structure3 ~hrough the
connection region 3' in the plane BBo
The plane of the section of Figure 1 includes the axis of the
fuel injector housing 1 and is very close to the axis of a cylinder
and of one of the columns 2 surrounding the several studs by which
the cylinder head is attached to the cylinder blockO The heat-
conducting structure is maintained at relatively low temperature bya flow of water which reaches it from a pump at one end of the engine
via a supply manifold 4, passes through two drilled passages 5 and 6
and returns via the return manifold 7 to the end of the engine, where
it is cooled by a radiator. The water extracts heat from structure 3
via the surfaces of the two manifolds as wéll as via the surfaces
106Z568
of the passages 5 and 6 though it will be appreciated that the
temperature of the lower deck 8 is much higher than that of the
upper deck 9 of the head9 so that the local heat transfer rates
will be highest at the lower ends of the passages 5 and 60
In Figure 2 the air inlet port in deck 8 is seen at 10 and the
air ex~aust port at 11. The position of the cylinder bore in
relation to the cylinder head is indicated by 129 and the position
of an offset combustion chamber bowl in the piston crown is
indicated by 130 It is the cylinder head surface opposite this
bowl that is most int~nsely heatedO All the stud columns 2
surrounding this cylinder are seen in sectionO The section ~-~ is
taken just above deck 8 and shows the cross-section 14 of the
connection region 39 between the cooled heat-conducting structure 3
and the deckO This section registers with the area of the deck
: 15 that requires direct cooling to maintain satisfactory temperatures
throughout the componentO This area includes the bridge between the
air port 10 and the exhaust port llo It extends round most of that
part of the air port 10 which lies above the combustion chamber
bowl 13 and it extends somewhat further round the exhaust port
because the exhaust valve seat receives more heatO The area also
includes the whole of the area below the nozzle cap sealing
washer 15 but it will be appreciated that the heat extracted from
deck 8 on that side of the nozzle remote from the cylinder axis will
be considerably less than by an annular water-cooling passage, while
on the hotter side9 where more effeGtive cooling is necessary9 this
106Z568
is provided by the flow of water in passage 6~ It will be noted
that the manifolds 4 and 7 fulfil an extra task of cooling the inlet
and outlet valve guide housings that are situated between them.
As an example of the control of lateral heat flow to the
directly-cooled region by choice of local thickness of the
component, Figures 1 and 2 show in broken lines an optional
depression 16 in the upper surface 8" of deck 8 which limits
lateral flow of heat to the cooled structure 3 from that part of
the deck below the air inlet passage, this being a region of the
deck where in some cases the metal temperatures would otherwise be
unnecessarily low.
Figure 3 shows the part of the cylinder head covering one
cylinder, in the longitudinal plane of the valve axes~
~ igures 4 to 6 show another example of the invention1 using air
15 as the coolant fluid. Here what requires cooling is a region of the
lower deck 30 of a cylinder head consisting of an upper part 21 and
a lower part 22. The heat-conducting structure includes cooling
fins 32 connected to the top surface 30l of deck 30~ parts of the lower
surface 30ll of which are exposed in use to the combustion zones of
the cylindersO Part 21 comprises upper decks 23 and 241 bridged
by a number of cylinder head stud columns 25 and valve guides 26,
and joined by sides 27 and 28 forming a box structure with projecting
walls 29 which form the lower part of an enclosure for the valve
levers and associated partsO Part 22 comprises the lower deck 30
25 and various projectionsO The two parts are located in relationship
106Z568
to one another by dowels and are clamped together and to the
cylinder clock (not shown) by the cylinder head studs and nuts.
The two parts form a passage for the flow of cooling airO The
passage comprises an inlet portion 31, a central portion in which
5 are mounted the cooling fins 32, one of which is seen9 and an outlet
portion 33. Holes through the three decks and a seating at 34 are
provided to accommodate a fuel injectorO The cooling fins 32 make
contact with lower deck 30 over a limited area through a connection
region including the raised portion 35 of the deck, and beyond this
area the fins are separated from the deck by the air gaps 36 and 370
The area of raised portion 35 upon surface 30 l of lower deck 30
registers as nearly as possible with the area of the surfaoe region
that needs direct cooling in order to maintain satisfactory
temperatures throughout the componentO Were it preferred to mount
fins 32 directly upon surface 30~ 9 instead of directly upon the
raised portion 359 the envelope of the areas of contact between all
the individual fins and the surface should substantially correspond
to the cross-section of portion 350
Figure 5 shows the configuration of the air passage walls9 38
20 and 39, which act also as cooling fins swept by air on one side, and
of two cooling fins 32 and 40 arranged above the cylinder bore (which
is indicated by the broken line 41) one on either side of the injector
seating 34, and dividing the space between the walls 38 and 39 into
three passages, presenting six heat exchange surfacesO Inlet cooling
25 air approaching the fuel injector is channelled into the central
106Z568
passage and the remaining air passes through the outer passagesO
The minimum combined width of the flow passages9 passage walls and
fins is equal to the minimum distance between the air inlet passage 42
and the exhaust passage 43 which is "siamesed" with the similar
5 passage 44 of the adjacent cylinder, these three passages being seen
here in plan view. After passing the fins, the cooling air flows
with little resistance to the outlet at the side of the cylinder
head, since the outlet portion of the passage extends under the
exhaust passage 430 The inlet and exhaust passages are made of heat-
resistant steelO Figure 5 shows the outline 359 and thus the extentof the area of the raised portion 35 (Figure 4) of deck 30
constituting the link region through which direct cooling is appliedO
This area is similar in shape to the corresponding area requiring
cooling in Figures 1 to 30 Cooling of the parts, such as 469 of the
5 raised portion 35 which would otherwise project beyond the cooled
passage walls is improved by locally increasing the width of the
passage walls near the deck 309 as indicated for example at 470
An air duct conveying air from a fan or other source (not shown)
in known manner, and which may serve also to supply air for cooling
the cylinder, is connected to the inlet portion 31 of the cylinder
head air passage by means of studs mounted in tapped hol~s. 48
(Figure 4) . After passing through the outlet portion 33 of the
passage, the cooling air escapes in the normal way directly to the
atmosphere~
1062568
The section of Figure 6, which shows the part of the cylinder
head covering one cylinder, is taken in the longitudinal plane of
the valve axes.
It will be noted that when air is used as the coolant, the
cool body (i.e. heat-conducting structure) applied to the selected
areas of the deck from which heat is to be extracted comprises
essentially a block of metal in which are formed air flow pas~ages
instead of the water flow passages of the water-cooling version. The
cool body thus becomes a number of fins, the outer fins conveniently
forming the walls of the air flow passage through the cylinder head.
The main featùres distinguishing such an arrangement from the normal
use of cooling fins in air-cooled engines are that the fins are
attached to the limited selected areas corresponding withthe regions to
be cooled, and that their projections beyond these areas are
separated from the cylinder head deck by air gaps. Another difference
is that in known designs, cooling fins are placed all over the
cylinder head and only a fraction of the air passes over the critical
central regions, so that these critical regions are cooled largely
by lateral heat flow through the deck. To maintain the critical
regions at acceptable temperatures by this means, it is necessary to
cool the surrounding regions to well below acceptable temperatures,
thus removing heat unnecessarily.
In another alternative to the use of the r-aised portion 35 in
Figures 3-6 the three air passages between the fins, best seen in
Figure 6, may be carried much lower so that in the connection region
106Z568
between fins and deck the thickness of the deck 30 is reduced to
one half or less of that existing elsewhere, the fins and the
structure of upper decks 23~ 24 providing adequate support of the
deck against cylinder gas pressure; The choice will depend on the
extent to which the cooling effect needs to be localised in a
particular application.
As an alternative to the fin design shown in Figure 6, the
fins may slope outwards to make more use of the space between the
two gas passages and the two valve guides, thus providing more area
for air flow. Fins may also be attached directly to the valve
guides to cool them. The two-part construction facilitates casting
of the fins, which would be further assisted by tapering the fins in
accordance with common practiceO
