U.S. patent number RE34,226 [Application Number 07/713,405] was granted by the patent office on 1993-04-20 for cylinder head cooling for multiple valve engine.
This patent grant is currently assigned to Yamaha Hatsudoki Kabushiki Kaisha. Invention is credited to Isao Morishita.
United States Patent |
RE34,226 |
Morishita |
April 20, 1993 |
**Please see images for:
( Certificate of Correction ) ** |
Cylinder head cooling for multiple valve engine
Abstract
A cooling jacket arrangement for the cylinder head of a multiple
valve internal combustion engine embodying a single camshaft for
operating all of the valves. The cooling jacket is supplied with
coolant in proximity to portions of the cylinder head that support
the exhaust valves and coolant is discharged from outlets formed in
portions of the cylinder head that journal the intake valves so as
to insure uniform cylinder head temperature. The invention is
disclosed in combination with either single or multiple spark plug
arrangements and in each embodiment at least a portion of the spark
plug is also surrounded by the cooling jacket.
Inventors: |
Morishita; Isao (Iwata,
JP) |
Assignee: |
Yamaha Hatsudoki Kabushiki
Kaisha (Iwata, JP)
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Family
ID: |
26468236 |
Appl.
No.: |
07/713,405 |
Filed: |
June 10, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
357473 |
May 26, 1989 |
04972807 |
Nov 27, 1990 |
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Foreign Application Priority Data
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May 30, 1988 [JP] |
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63-134053 |
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Current U.S.
Class: |
123/41.82R;
123/41.76 |
Current CPC
Class: |
F02B
61/02 (20130101); F02F 1/40 (20130101); F02F
1/4221 (20130101); F02B 1/04 (20130101); F02B
61/06 (20130101); F02B 2075/027 (20130101); F02B
2275/20 (20130101); F02F 2001/241 (20130101); F02F
2001/245 (20130101) |
Current International
Class: |
F02B
61/00 (20060101); F02F 1/40 (20060101); F02B
61/02 (20060101); F02F 1/42 (20060101); F02F
1/26 (20060101); F02F 1/24 (20060101); F02B
1/04 (20060101); F02B 75/02 (20060101); F02B
1/00 (20060101); F02B 61/06 (20060101); F02F
001/36 () |
Field of
Search: |
;123/41.72,41.74,41.76,41.77,41.82R,193H,310,41.41 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kamen; Noah P.
Attorney, Agent or Firm: Beutler; Ernest
Claims
I claim:
1. A cylinder head for a liquid cooled internal combustion engine
have a lower sealing surface surrounding a combustion chamber area
defined in part by an associated cylinder, a plurality of intake
valves having stem portions reciprocally supported within portions
of said cylinder head about axes that lie at an acute angle to the
associated cylinder and cooperating with intake passages formed in
said cylinder head for sequentially delivering a charge to a pent
roof combustion chamber formed at least in part by said cylinder
head combustion chamber area, a plurality of exhaust valves having
stem portions supported for reciprocation within portions of said
cylinder head about axes that lie at an acute angle to the
associated cylinder and cooperating with exhaust passages formed in
aid cylinder head for sequentially discharging a burnt charge from
the combustion chamber, a cooling jacket formed within said
cylinder head contiguous to said combustion chamber area and
extending at least partially around the portions of said cylinder
head journaling at least some of said valve stems, said cylinder
head portions being at least partially encircled by said cooling
jacket in planes parallel to said cylinder head lower sealing
surface to define pockets on the sides of some of said valve stems
means for admitting liquid coolant to said cooling jacket in
proximity to at least one of said cylinder head portions and
adjacent at least one of said pockets for cooling the adjacent
valve stem, and means for discharging liquid coolant from said
cooling jacket in proximity to another of said cylinder head
portions.
2. A cylinder head as set forth in claim 1 wherein the means for
admitting liquid coolant to the cooling jacket is disposed in
proximity to a portion of the cylinder head that supports an
exhaust valve stem.
3. A cylinder head as set forth in claim 2 wherein the means for
discharging liquid coolant from the cooling jacket is positioned in
proximity to a portion of the cylinder head that journals an intake
valve stem.
4. A cylinder head as set forth in claim 1 wherein there are plural
inlets to the cooling jacket each in proximity to one of the
cylinder head portions and adjacent a pocket formed thereby.
5. A cylinder head as set forth in claim 4 wherein all of the
cooling jacket inlet portions are in proximity to portions of the
cylinder head that support the exhaust valve stems and adjacent
pockets thereof.
6. A cylinder head as set forth in claim 5 wherein there are plural
outlets for discharging coolant from the cooling jacket.
7. A cylinder head as set forth in claim 6 wherein each of the
outlets is positioned in proximity to a portion of the cylinder
head that supports an intake valve stem.
8. A cylinder head as set forth in claim 1 further including a
spark plug supporting pocket formed in the cylinder head, said
spark plug supporting pocket being at least in part encircled by
the cooling jacket.
9. A cylinder head as set forth in claim 8 wherein the spark plug
pocket is formed centrally of the combustion chamber and is
completely surrounded by the cooling jacket.
10. A cylinder head as set forth in claim 8 wherein there are a
pair of spark plug pockets formed on opposite sides of the cooling
jacket and at least partially encircled thereby.
11. A cylinder head as set forth in claim 1 further including a
single camshaft journaled by said cylinder head and means for
operating all of the valves from said single camshaft.
12. A cylinder head as set forth in claim 11 wherein the means for
admitting liquid coolant to the cooling jacket is disposed in
proximity to a portion of the cylinder head that supports and
exhaust valve stem and adjacent a pocket formed thereby.
13. A cylinder head as set forth in claim 12 wherein the means for
discharging liquid coolant from the cooling jacket is positioned in
proximity to a portion of the cylinder head that journals an intake
valve stem.
14. A cylinder head as set forth in claim 11 wherein there are
plural inlet to the cooling jacket each in proximity to one of the
cylinder head portions and adjacent pockets thereof.
15. A cylinder head as set forth in claim 14 wherein all of the
cooling jacket inlet portions are in proximity to portions of the
cylinder head that support the exhaust valve stems and adjacent
pockets thereof.
16. A cylinder head as set forth in claim 15 wherein there are
plural outlets for discharging coolant from the cooling jacket.
17. A cylinder head as set forth in claim 16 wherein each of the
outlets is positioned in proximity to a portion of the cylinder
head that supports an intake valve stem.
18. A cylinder head as set forth in claim 11 further including a
spark plug supporting pocket formed in the cylinder head, said
pocket being at least in part encircled by the cooling jacket.
19. A cylinder head as set forth in claim 18 wherein the spark plug
supporting pocket is formed centrally of the combustion chamber and
is completely surrounded by the cooling jacket.
20. A cylinder head as set forth in claim 18 wherein there are a
pair of spark plug supporting pockets formed on opposite sides of
the cooling jacket at least partially encircled thereby. .Iadd.
21. A cylinder head for a liquid cooled internal combustion engine,
said cylinder head being defined by a lower surface having a
recessed portion forming at least in part a combustion chamber and
a surrounding planer portion for sealing cooperation with an
associated cylinder block, at least two first ports extending
through one side of said cylinder head and terminating in a pair of
spaced apart first valve seats on one side of said recess, at least
two second ports extending through the other side of said cylinder
head and terminating a pair of spaced apart second valve seats
formed on the other side of said recess, and a cooling jacket
formed internally of said cylinder head and extending substantially
between said sides for receiving a liquid coolant, said cooling
jacket being defined in part by internal spaced apart first and
second walls defining said first ports so that said cooling jacket
extends substantially from said one side of said cylinder head and
between said two first ports, said cooling jacket being further
defined by a third wall extending from the other side of said
cylinder head and which defines both of said second ports and which
extends back to the other side of said cylinder head so that said
cooling jacket does not extend in any substantial extent between
said second ports. .Iaddend. .Iadd.22. A cylinder head for a liquid
cooled internal combustion engine as set forth in claim 21 further
including a spark plug mounted within said cylinder head and
extending between said
two first ports. .Iaddend. .Iadd.23. A cylinder head for a liquid
cooled internal combustion engine as set forth in claim 22 wherein
the spark plug extends through the cooling jacket and is surrounded
by a fourth generally cylindrical wall. .Iaddend. .Iadd.24. A
cylinder head for a liquid cooled internal combustion engine as set
forth in claim 23 wherein the cylindrical wall is inclined to the
planer portion of the cylinder head. .Iaddend. .Iadd.25. A cylinder
head for a liquid cooled internal combustion engine as set forth in
claim 24 wherein the first ports comprised exhaust ports. .Iaddend.
.Iadd.26. A cylinder head for a liquid cooled internal combustion
engine as set forth in claim 25 wherein the spark plug is
positioned with its spark plug gap substantially at the center of
the combustion chamber. .Iaddend. .Iadd.27. A cylinder head for a
liquid cooled internal combustion engine as set forth in claim 21
wherein there are at least three second ports extending from the
other side of the cylinder head and each terminating at a
respective valve seat on the other side of the recess. .Iaddend.
.Iadd.28. A cylinder head for a liquid cooled internal combustion
engine as set forth in claim 27 wherein the third wall defines at
least in part all of the second ports. .Iaddend.
.Iadd.29. A cylinder head for a liquid cooled internal combustion
engine as set forth in claim 28 further including a spark plug
mounted within said cylinder head and extending between said two
first ports. .Iaddend. .Iadd.30. A cylinder head for a liquid
cooled internal combustion engine as set forth in claim 29 wherein
the spark plug extends through the cooling jacket and is surrounded
by a fourth generally cylindrical wall. .Iaddend. .Iadd.31. A
cylinder head for a liquid cooled internal combustion engine as set
forth in claim 30 wherein the cylindrical wall is inclined to the
planer portion of the cylinder head. .Iaddend. .Iadd.32. A cylinder
head for a liquid cooled internal combustion engine as set forth in
claim 23 wherein the first ports comprised exhaust ports. .Iaddend.
.Iadd.33. A cylinder head for a liquid cooled internal combustion
engine as set forth in claim 32 wherein the spark plug is
positioned with its spark plug gap substantially at the center of
the combustion chamber. .Iaddend. .Iadd.34. A cylinder head for a
liquid cooled internal combustion engine as set forth in claim 27
wherein the first ports comprise exhaust ports and the second ports
comprise intake ports.
.Iaddend. .Iadd.35. A cylinder head for a liquid cooled internal
combustion engine as set forth in claim 34 wherein the second ports
all extend from a common opening in the other side of the cylinder
head to the respective valve seats. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to a cylinder head cooling arrangement for
multiple valve engines and more particularly to an improved
arrangement for cooling the combustion chamber of a multiple valve,
single overhead camshaft internal combustion engine.
As is well known, there is a trend in internal combustion engines,
particularly those employed for powering motor vehicles, to
increase the performance of the engine through the use of multiple
valves. Although multiple valve engines have the ability to
significantly increase the performance of the engine for a given
displacement, there are numerous problems to be solved in
connection with the use of multiple valve engines. For example,
when plural intake and exhaust valves are employed in an overhead
valve engine, the area of the engine which is available to provide
cooling for the combustion chamber, particularly on the cylinder
head side, is significantly diminished. It is, of course, extremely
important to control the cooling of the cylinder head so as to
prevent unduly high temperatures which can give rise to numerous
and well known defects. Furthermore, in addition to the problem of
providing adequate cooling volume, it is also desirable to insure
an appropriate coolant flow through the cylinder head so as to
insure that cylinder head temperatures will be more uniform,
particularly across the combustion chamber, so as to avoid hot
spots and the disadvantages attendant thereto.
It is, therefore, a principal object of this invention to provide
an improved cooling arrangement for the cylinder head of a multiple
valve internal combustion engine.
It is further object of this invention to provide an improved
cylinder head cooling arrangement for high performance multiple
valve engines and an arrangement for insuring the proper coolant
flow through the cylinder head cooling jacket.
In conjunction with the use of multiple valve engines, it is
desirable if the number of camshafts required to operate the
multiple valves can be reduced. This is, it is desirable to provide
a relatively simple construction for operating all of the valves of
a multiple valve engine. However, as the number of camshafts is
reduced, the configuration of the cylinder head also becomes a
problem. That is, the position of a single camshaft for operating
all of the valves can give rise to certain difficulties in location
of the spark plug. Basically, it is desirable to place the spark
plug or spark plugs at substantially central locations in the
combustion chambers so that the flame travel can be complete to all
parts of the combustion chamber. However, with such spark plug and
camshaft positioning, the problems of the provision of adequate
cooling for the cylinder head become magnified.
It is, therefore, a still further object of this invention to
provide an improved cylinder head arrangement for a multiple valve
engine embodying a single overhead camshaft and having an effective
cooling arrangement for the combustion chamber.
SUMMARY OF THE INVENTION
This invention is adapted to be embodied in a cylinder head for a
liquid cooled internal combustion engine which cylinder head has a
lower surface which surrounds a combustion chamber area. A
plurality of intake valves have stem portions supported for
reciprocation within the cylinder head and cooperate with intake
passages formed in the cylinder head for sequentially delivering a
charge to a combustion chamber formed at least in part by the
cylinder head combustion chamber area. A plurality of exhaust
valves have stem portions which are supported within the cylinder
head and which cooperate with exhaust passages formed in the
cylinder head for sequentially discharging a burnt charge from the
combustion chamber. A cooling jacket is formed within the cylinder
head contiguous to the combustion chamber area and extends at least
partially around the portions of the cylinder head that journal
some of the valve stems. Means are provided for admitting a liquid
coolant to the cooling jacket in proximity to at least one of the
cylinder head portions and means are provided for discharging
liquid coolant from the cooling jacket in proximity to another of
the cylinder head portions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of a motorcycle powered by an
internal combustion engine constructed in accordance with an
embodiment of the invention, with a portion broken away.
FIG. 2 is an enlarged cross-sectional view taken through one of the
combustion chambers of the engine along a plane that passes
generally through the axis of the cylinder bore.
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG.
1 and shows a portion of the cylinder head cooling jacket.
FIG. 4 is a bottom plan view of the cylinder head with the
associated components removed as shown in phantom.
FIG. 5 is a cross-sectional view taken generally along the line
5--5 of FIG. 2.
FIG. 6 is a cross-sectional view, in part similar to FIG. 2,
showing another embodiment of the invention.
FIG. 7 is a cross-sectonal view taken along the line 7--7 of FIG.
6.
FIG. 8 is a bottom plan view of the cylinder head of this
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1, a motorcycle powered by an internal
combustion engine constructed in accordance with an embodiment of
the invention is identified generally by the reference numeral 11.
The motorcycle 11 is depicted as a typical environment in which an
engine embodying the invention may be employed. The invention has
particular utility in conjunction with internal combustion engines
used to power vehicles. However, it will be readily apparent to
those skilled in the art that the invention may be practiced in
conjunction with other engine applications.
The motorcycle 11 is comprised of a frame assembly, indicated
generally by the refernce numeral 1.2, and which is of the welded
up type including a head pipe 13 that journals a front fork
assembly 14 for steering movement and which supports a front wheel
15 in a known manner. In a similar manner, a rear wheel 16 is
supported by the frame assembly 12 by means including a trailing
arm suspension 17.
An internal combustion engine, indicated generally by the reference
numeral 18 and shown in more details in FIGS. 2 through 5, is
supported within the frame assembly 12 by means including an engine
mount 19 that is affixed to a gusset plate 21 which is affixed to
or forms a part of the frame assembly 12. The engine 18 is further
supported in a suitable manner from a down tube 22 of the frame
12.
A fuel tank 23 is supported by the frame 12 above the engine 18 and
supplies fuel to the engine in a known manner and specifically to
carburetors 24 thereof. An air cleaner 25 supplies filtered air to
the carburetors 24.
A seat 26 is supported on the rear of the frame assembly 12 behind
the fuel tank 23 so as to accommodate a rider.
The engine 18, as is common with motorcycle practice, includes an
integral crankcase, change speed transmission assembly 27 that
drives the rear wheel 16 through a chain 28 in a known manner.
The engine 18 or at least portions of its are water cooled and for
this purpose there is mounted a radiator 30 on the frame assembly
12 forwardly of the down tube 22. The construction of the
motorcycle and its drive arrangement as thus far described may be
considered to be conventional and, for the reason, further
description of the motorcycle per se is not believed to be
necessary to understand the construction and operation of the
invention.
Referring now, therefore, primarily to FIGS. 2 through 5, the
details of the engine 18 which form the part of the invention will
now be described. In the drawings, only a single cylinder and
specifically the combustion chamber and valve mechanism and
cylinder head arrangement therefor have been illustrated in detail
since the bottom end of the engine and its construction forms no
part of the invention. Also, the application of the invention to
multiple cylinder engines is believed to be well within the scope
of those skilled in the art.
The engine 18 includes a cylinder block 29 which may be considered
to be conventional and which has a cylinder bore 31 in which a
piston 32 is supported for reciprocation. The cylinder bore 31 is
provided by a cylinder liner 33 that is pressed or otherwise
secured into the cylinder block assembly 29 and specifically a main
casting 34 thereof. The piston 32 drives a crankshaft (not shown)
in a known manner.
A cylinder head, indicated generally by the reference numeral 35,
is affixed to the cylinder block 29 and is formed with a lower
sealing surface which surrounds a combustion chamber recess 36 and
that is adapted to be affixed in sealing relationship to the upper
surface of the cylinder block 29 with an interposed gasket (not
shown). The piston 32 and specifically its head and the cylinder
bore 31 form with the cylinder head combustion chamber recess a
chamber, the volume of which cyclically varies during the
reciprocation of the piston 32 as is well known.
The engine 18 is provided with an induction system that comprises a
first pair of intake valves 37 which are supported for
reciprocation about parallel axes within valve guides pressed into
the cylinder head 35. The axes of reciprocation of the first pair
of intake valves 37 is disposed at an acute angle to a plane
perpendicular to the plane of FIG. 2 and containing the axis of the
cylinder bore 31. There is further provided a third intake valve 38
which also is supported for reciprocation within the cylinder head
35 by means of a pressed in intake valve guides and the intake
valve 38 also reciprocates about an acute angle to the
aforementioned plane. However, the axis of reciprocation of the
intake valve 38 is at a lesser angle than the axes of reciprocation
of the intake valves 37 to this plane, as described in U.S. Pat.
No. 4,660,529, entitled "Four Cycle Engine", issued Apr. 28, 1987,
and assigned to the assignee of this application.
Each of the intake valves 37 and 38 is urged toward its closed
position by means of a coil spring assemblage 39 which bears
against a respective pad 41 engaged with a surface of the cylinder
head 35 and a retainer 42 that is affixed by means of a keeper
assembly to the upper end of the stem of the respective intake
valve. The valves 37 and 38 are opened in a manner which will be
described.
The intake valves 37 and 38 control the flow of a fuel/air charge,
formed by the carburetors 24, through an induction passage 43 that
is formed in one side of the cylinder head assembly 35 and which
terminates in valve seats 44 associated with the pair of intake
valves 37 and a valve seat 45 associated with the remaining intake
valve 38. The valve seats 44 and 45 may be suitably pressed within
the cylinder head 35 in a known manner.
The induction passage 43 forms a single opening 46 in the intake
side of the cylinder head 35 and a manifold section 47 is affixed
to this intake side. The manifold section 47 includes two intake
openings 48 which are separated by a dividing portion 49 that has a
generally triangular shape configuration so as to merge the two
intake openings 48 gradually into a single opening at the cylinder
head opening 46. This permits the use of two carburetors 24 that
are affixed to the manifold 47 for delivering adequate fuel/air
charge to the three intake valves 37 and 38. Of course, other forms
of charge forming systems including fuel injection systems may be
utilized in conjunction with the invention.
The cylinder head 35 also supports a pair of exhaust valves 51 that
are disposed generally on the opposite side of the aforenoted plane
and which have stem portions that are reciprocally supported within
the cylinder head 35 about parallel axes. The axis of reciprocation
of the exhaust valves 51 is at an acute angle to the aforenoted
plane and this angle is greater than the angle of reciprocation of
the single intake valve 38 and lesser than the angle of
reciprocation of the pair of exhaust valves 37, as noted in
aforenoted U.S. Pat. No. 4,660,529. The exhaust valves 51 are urged
to their closed position by means of coil compression springs 52
that are loaded in a manner similar to the springs 35 of the intake
valves 37 and 38. These exhaust valves 51 are opened in a manner
which will be described.
The exhaust valves 51 control the flow of exhaust gases through a
pair of respective exhaust ports 53 that extend through the
opposite side of the cylinder head from the intake port 41. The
exhaust ports 53 originate at respective valve seats 54 that
cooperate with each of the exhaust valves 51 in a known manner to
control the flow of exhaust gases from the combustion chamber 37
into the exhaust ports 53. Is should be noted that the exhaust
ports 53 diverge generally from the plane that is perpendicular to
the aforenoted plane and which is parallel to the plane of FIG. 2
so that the engine can clear the single down pipe 22 of the frame
assembly as clearly shown in FIG. 5. In this way, the engine can
have adequate breathing capability and a relatively simple
construction.
Because of the orientation of the intake valves 37 and 38 and the
exhaust valves 51, as seen in FIG. 2, the combustion chamber has a
generally pent roof type of configuration. This is also as
described more fully in afornoted U.S. Pat. No. 4,660,529.
The intake valves 37 and 38 and exhaust valves 51 are all operated
by means of a single overhead camshaft 55 that is journaled on the
cylinder head assembly 35 for rotation about a camshaft axis that
extends generally parallel to the aforementioned plane passing
through the cylinder bore axis and perpendicular to the plane of
FIG. 2. The camshaft axis is, however, offset toward the intake
valves 37 and 38 and the intake valves 37 and 38 lie substantially
on one side of a plane parallel to the aforenoted plane and
containing the axis of rotation of the camshaft 55 while the
exhaust valves 51 lie on the other side of this plane.
The manner of support for the camshaft 55 is described in my
copending application entitled "Camshaft Arrangement For
Multi-Valve Engine", Ser. No. 357,477, filed May 26, 1989 and
assigned to the assignee of this application or my copending
application entitled "Combustion Chamber And Valve Operating
Mechanism For Multi-Valve Engine", Ser. No. 357,474, filed May 26,
1989 and also assigned to the assignee of this application Since
the manner of driving and supporting the camshaft 55 is not
necessary to understand the construction and operation of this
invention, the disclosures of those copending application are
incorporated herein by reference and will not be described again in
connection with this application. It should be noted, however, that
the camshaft 55 is positioned generally above an arcuately
configured upper wall of the cylinder head assembly 35.
The bearing assembly for the camshaft 55 includes a cam cover and
bearing cap assembly, indicated generally by the reference numeral
56 and which pivotally supports rocker arm assemblies 57 and 58 in
the manner described in the aforenoted copending applications, for
example, by rocker arm shaft 60, for operating the intake valves 37
and 38 and exhaust valves 51, respectively. The number of rocker
arms employed for this purpose can be varied and since the rocker
arm and valve operating mechanism forms no part of the invention,
these features are not believed to be necessary to understand the
construction and operation of the embodiment of the invention.
As should be readily apparent, the use of a single camshaft 55 for
operating all of the valves 37 and 38 and 51 simplifies the overall
construction. However, the central positioning of the camshaft 55
makes it difficult, with conventional constructions, to position
the spark plug for the engine at the center of the combustion
chamber 37. In accordance with the invention, however, there is
provided a spark plug well 59 consisting of aligned bores 61 and 62
formed in the cam cover 56 and cylinder head 35, respectively, to
pass a spark plug 63. The cylinder head is formed with a tapped
spark plug receiving opening 64 in which the spark plug 63 is
received so that its gap is disposed substantially at the center of
the combustion chamber 37 as may be best seen in FIG. 4. This
permits good flame propagation and insures complete combustion
under all running conditions.
It should be readily apparent from the foregoing description that
the configuration of the cylinder head using multiple intake and
exhaust valves all operated by a single overhead camshaft and the
associated porting therefor provides a relatively complicated and
complex cylinder head construction. In addition, this overall
relationship results in an area which makes it very difficult to
assure adequate and even cooling for the combustion chamber and the
components associated therewith.
However, in accordance with the invention, the cylinder head 35 is
provided with a very large capacity cooling jacket 65 which is
configured as best shown in FIG. 2 and 3, so as to substantially
surround the spark plug well 59 and also to extend substantially in
part around the portions of the cylinder head that reciprocally
support the stems of the intake valve 37 and 38 and the exhaust
valves 51 as clearly shown in FIG. 3. In fact, the cooling jacket
65 extends around greater than 180.degree. of the bearing area of
the respective valve stems so as to insure good and adequate
cooling for them. Furthermore, the cooling jacket 65 extends
between the cylinder head surface below the camshaft 55 and a lower
surface 66 thereof which is adjacent the combustion chamber wall 37
so as to insure good cooling.
It will also be noted that the cylinder head 35 is affixed to the
cylinder block 29 by means of a plurality of studs 67 and these
studs are disposed at the corners of the combustion chamber 36 but
outwardly of the area where the valves 37, 38 and 51 are supported
so as to not interfere with the volume of the cooling jacket
65.
In addition to providing an adequate area cooling jacket, it is
also essential to insure that the flow of coolant through the
cooling jacket 65 will be in the appropriate direction and
appropriate volumes so as to provide equal cooling across the
entire combustion chamber so that there are no localized hot spots.
To this end, coolant is delivered to the cooling jacket 65 in
proximity to the portions of the cylinder head that support the
exhaust valves 51 (the more highly heated valves) by means of a
first inlet 68 that is disposed in the recess between the portion
of the cylinder head that journals the exhaust valves 51 and a pair
of outer inlets 69 that are each disposed between the cylinder head
studs 67 and the cylinder head portion that journals the outer side
of the exhaust valves 51. Water is delivered to these inlet 68 and
69 from a cooling jacket 71 of the cylinder block 29.
The coolant then flows in the direction of the arrows shown in FIG.
3 from the inlets 68 and 69 across the cooling jacket 65 toward a
pair of spaced outlets 72 that are disposed outwardly of the
portion of the cylinder head where the intake valve stems 37 are
supported and the adjacent cylinder head studs 67. As a result, the
hotter exhaust valves will be cooled first and then the cooler
intake valves will be cooled.
Coolant is discharged from the cooling jacket 65 and specifically
the outlets 72 to a water manifold 73 that extends across the
rearward portion of the cylinder head 35 from a first exit port 74
that communicates with one of the passages 72 and a cross passage
75 which then is intersected by a passage 77 exiting from the other
cylinder head outlet 72 for return to the radiator 30 for cooling.
Of course, this circulation is effected by a suitable pressure pump
(not shown) and thermostat.
It should be readily apparent, therefore, that the described
arrangement is highly effective in insuring that the cylinder head
will be adequate cooled and all components associated therewith
will be cooled in the proper relationship so as to maintain
substantially uniform temperatures across the cylinder head.
In the embodiment of the invention as thus far described, the
engine has been provided with a single spark plug for the
combustion chamber. In some instances, particularly where large
bore engines are employed, it may be desirable to employ two spark
plugs per cylinder so as to insure that the complete charge in the
chamber will be burned, even under extreme high speed running
conditions.
It has been previously noted that there is considerable difficulty
in obtaining the desired spark plug positioning for even a single
spark plug with a single camshaft multiple valve engine. However,
in accordance with the invention, it is possible also to locate two
spark plugs for each cylinder bore and combustion chamber while
still affording access to the spark plugs and an adequate cooling
jacket for the cylinder head. Such an engine is illustrated in
FIGS. 6 through 8 and is identified generally by the reference
numeral 101.
Except for the positioning of the spark plugs in this engine, the
basic configuration of the combustion chamber, cooling jacket and
coolant flow therethrough is the same as the previously described
embodiment. For that reason, components of this embodiment which
are the same as those of the previously described embodiment have
been identified by the same reference numerals and will be
described again only insofar as is necessary to understand the
construction and operation of this embodiment.
In this embodiment, there are provided in the cylinder head
assembly 35 and cam cover, bearing cap assembly 56 a pair of spark
plug wells 102 that are formed on diametrically opposite sides of
the cylinder head 102 and in a plane that extends generally
parallel to the plane aforenoted containing the cylinder bore axis
and, in fact, may be coincident with it. A pair of spark plugs 103
are received, one in each of these wells and have their gaps
disposed in the combustion chamber as best shown in FIG. 8 wherein
the spark plug gaps are disposed so that the flame travel from them
will encompass the entire combustion chamber under all running
conditions so as to insure complete combustion. It will be noted
that the spark plug wells 102, as may be best seen in FIG. 7, are
disposed out of the center of the cooling jacket 65 but
nevertheless protrude substantially into it in the area of the
inlets 69 and outlets 72 so as to insure adequate cooling in this
area.
From the foregoing descriptions, it should be clear that two
embodiments of the invention have been illustrated and described
and each of which provides an adequate and copious cooling jacket
for the cylinder head of a multiple valve internal combustion
engine even when the construction incorporates only a single
camshaft for operating the valves and wherein either one centrally
positioned or multiple spark plugs are employed. Although two
embodiments of the invention have been illustrated and described,
various changes and modifications may be made without departing
from the spirit and scope of the invention, as defined by the
appended claims.
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