Valve train for internal combustion engine

A valve train for internal combustion engines utilizing an inverted bucket tappet with a pivot structure operatively disposed between the tappet and the end of the valve stem allowing the valves to be angulated with respect to each other and to the axis of the cylinder in both the transversal and the horizontal planes of the engine. Accordingly on a multi-valve engine, the valves extend radially from the associated combustion chamber to open and increase space in the center of the cylinder head for spark plugs, injectors, or pre-combustion chambers and so that the combustion chamber can be designed with a hemispherical surface, with tangentially disposed valve heads. The construction allows the use of large valves in conjunction with stronger, better-cooled valve seats and bridges. The tappets can be actuated conventionally by direct-acting overhead camshafts, by rocker arms and "T" bridges.

FIELD OF THE INVENTION 
This invention relates to internal combustion engines, and more 
particularly, to a new and improved engine valve train layout with 
angulated intake and exhaust valves radiating from the curved upper wall 
of the combustion chamber and having pivot structure between the valve 
stems and their tappets capable of being actuated by conventional cam 
shafts, pivot fingers, rocker arms and "T" or T-shaped bridges. 
BACKGROUND OF THE INVENTION 
Prior to the present invention, a wide range of valve trains with various 
valve and tappet configurations have been designed for internal combustion 
engines. A plurality of such valve trains are disclosed on pages 318-319 
of Automotive Handbook, 2nd Edition .COPYRGT. Robert Bosch GmbH, 1986 
Postfach 50, D-7000 Stuttgart 1, Germany. While these valve trains are 
satisfactory for their intended applications, they are generally not 
suitable for use with hemispherical and similar combustion chambers 
designed for advanced engines and do not provide additional center space 
in the cylinder head for large, well cooled injection or ignition devices. 
In U.S. Pat. No. 5,080,057, issued Jan. 14, 1992 to Batzill et al for 
"Cylinder Head of an Internal-Combustion Engine", a valve train is 
disclosed with intake and exhaust valves used with hemispherical 
combustion chambers that are inclined with respect to axes in the head 
construction of the engine. To actuate the disclosed valves, inverted 
bucket tappets are disposed so that they are in coaxial alignment with the 
valves. With such construction, camshafts with special conical cams or cam 
lobes are required to properly contact and actuate the valves for 
effective engine operation. The conical cam lobes of the Batzill 
construction are complicated and expensive. With such designs, a constant 
radius base circle on the lobe, requires a minimum tappet diameter 
increase over the basic tappet diameter of a conventional tappet and cam 
lobe, at least twice the radial distance between both sides of a conical 
cam lobe. Such a large tappet diameter, then, is counter-productive, for 
it forces the center of the lobe to be closer to the longitudinal center 
of the cylinder and results in less longitudinal plane inclination of the 
valves and reduced radial angle and curvature in the chamber. 
While there are various valve train designs for other hemispherical 
combustion chambers, such designs usually involve only two-valve 
operation. Although in these designs both the intake and exhaust valves 
emanate radially from the combustion chamber, their angularity is only on 
the transversal plane of the engine. Such designs are disclosed in the 
valve train design book by Philip H. Smith, C.Eng., M.I.Mech. E., 
M.S.A.E., "Valve Mechanisms for High-Speed Engines, Their Design and 
Development", published by Automobile Engineering and printed in 1967 by 
G. T. Foulis & Co. Ltd., 1-5 Portpool Lane, E.C. 1, London, in association 
with the Whitefriars Press Ltd., also of London and Tonbridge in the U.K. 
This Automobile Engineering publication also shows some designs of 
hemispherical chambers with four valves, driven by a variety of 
mechanisms. For example, the Hopwood-B.S.A. single cylinder motorcycle 
described in page 64 and shown by FIG. 3.23, indicates Single Overhead 
Camshafts, axially angled with respect to each other and connected by 
bevel gears, with the axis of each camshaft perpendicular to the single 
plane connecting each pair of same function valves and driving said valves 
conventionally by rocker arms operating in the plane of the valve stems. 
The four cylinder, four valve per cylinder BMW racing engine of 1967 is 
also described in the Automobile Engineering publication. In this engine, 
the four radial valves were conventionally driven by two camshafts via 
push rods and rocker arms. While the constructions of this publication are 
of interest, they are not functionally or structurally like that of the 
present invention. 
In addition to the above prior construction, one prior high speed diesel 
engine for passenger cars featuring a DOHC four valve with indirect 
injection is described in Automotive Engineering, January 1995 (vol. 103, 
No. 1), pages 23-25. This publication shows and describes a conventional 
DOHC, four valve design, with parallel valve stems for each pair of same 
function valves operating in conjunction with a hemispherical combustion 
chamber. In this prior design, the valves are angulated with respect to 
the longitudinal axis of the engine and increased head space is provided. 
The valves are not angulated with respect to each other in the 
longitudinal plane. However, the space is inadequate for many engine 
designs. Accordingly, the illustrated precombustion chamber of this engine 
is disposed quite far from the main combustion chamber, and is connected 
to it by a very long transfer passage. 
The present invention is readily adaptable to such prior art engines to 
advantageously provide more room in the center of the cylinder head so 
that the prechamber can be substantially lowered and the transfer passage 
can be shorter thereby reducing the volumes outside of the main chamber 
and increasing the corresponding volumes in such main chamber so that 
deeper intake valve pockets can be cut on the piston top, allowing the 
increased intake valve travel at top Dead Center during overlap such as is 
required by a variable valve timing mechanism. The present invention 
provides advanced construction augmenting engine operation including cold 
starting from advanced intake valve closing and the associated increase in 
Effective Compression Ratio. Besides, with the reduced prechamber and 
transfer passage volumes and correspondingly reduced heat transfer and 
pumping losses, the present invention produces increased compression 
temperatures needed for cold starting and smooth and quiet idle operation. 
The Automotive Engineering publication referenced above does not show or 
otherwise disclose the required shrouding of the heads of the parallel 
stem valves as they intersect the hemispherical combustion chamber 
machined in the cylinder head. Such shrouding is shown by FIG. 12, page 
329, of an article by Von Ulrich Conrad et al entitled "Die Neuen 
Viervientil-Diesel Motoren Von Mercedes-Benz", published in the 
July-August 1993 edition of MTU Magazine (MTZ 54, 1992, 7-8) a technical 
publication of Motoren-Turbinen Union, a division of Daimler-Benz AG. The 
disclosed shrouding creates very large and empty pockets which, if the 
valves were laid-out radially, could be transferred to the top of the 
piston, thus allowing the installation of the variable valve timing 
mechanism. Furthermore, this shrouding is so large, taking effect through 
such a large arcuate section of the valve periphery, that the air flow 
through the open valve suffers and adversely effects engine operation. 
Accordingly, and in spite of a very sophisticated air induction system, 
the rated engine power only increases 20% over the older two-valve engine 
which the disclosed engine replaces. 
In the applicant's invention, a 40% power increase may be readily obtained 
when applying this invention to four valve technology to replace the older 
two valve engines. Although intended to create more room so as to allow 
the placement of the spark plug or other combustion initiation means, the 
prior designs do not lend themselves to the larger radial angles desired 
in advanced engine design and as provided by the improvements of the 
present invention. 
The prior designs lacked the slide-pivot articulation of the present 
invention to open enough center-space for diesel injectors or prechambers 
due, in some cases, to the placement of the camshaft along the center 
longitudinal axis of the cylinder head, which would physically interfere, 
apart from the fact that the valves were not angulated with respect to 
each other in the longitudinal plane of the engine. 
More particularly, and in contrast to the prior constructions, the present 
invention provides a new and improved valve train that features the 
effective slide-pivot articulation interconnection of the bucket tappet 
with an outer end portion of the associated valve stem. This improved 
interface articulation between the tappet and valve stem allows the tappet 
to be stroked along a first axis and the associated valve to be stroked 
along a second axis which radiates from a point within the combustion 
chamber having a curved interior wall. 
The present invention meets higher standards with (1) the provision of a 
new and improved combustion chamber, preferably hemispherical in 
configuration, in the head of the engine and (2) intake of air into and 
exhaust of gas from the engine cylinder by pairs of intake and exhaust 
valves laid out so that the heads of these valves are substantially 
tangent to the hemispherical wall of the combustion chamber and so that 
the stems of these valves extend radially therefrom and outwardly from one 
another. 
The valve stems, accordingly, extend outwardly and preferably with respect 
to a common point of origin within the cylinder associated with the 
combustion chamber. The end portions of these stems interface with the 
inverted buckets or camshaft tappets by slide-pivot and force transmitting 
construction. With such articulation, conventional actuators, such as 
DOHC, pivot finger, rocker arms and "T" bridges can be used to displace 
each of the buckets along a first axis associated therewith and the 
associated intake or exhaust valve can be displaced along a second and 
intersecting axis that is coaxial with the radiating valve stem. 
With this invention, specially shaped conical cam lobes are eliminated 
since the face of each cam lobe is generally parallel to the axis of the 
camshaft and makes full line contact with the tappet. This arrangement may 
further provide for and feature larger headed intake and exhaust valves 
resulting in increased and improved cylinder air intake and gas exhaust 
for improved engine operation. With the improved cylinder head layout, the 
bridges in the combustion chamber wall between the valve seats are 
enlarged providing for strengthened constructions. Bridge cooling is also 
improved since there are increased effective volumes in the water jacket 
in-between the divergent ports, especially the exhaust ports, in the 
longitudinal plane. 
Another feature, object and advantage of this invention is to provide an 
internal combustion engine with a generally hemispherical combustion 
chamber having radiating intake and exhaust valves operated by inverted 
bucket tappets with internal universal articulation structures so that all 
the bucket tappets are displaced along parallel first axes while the 
associated valves are displaced along their respective radiating axes 
which are angled with respect to the first axes. 
These and other features, objects and advantages of this invention will 
become more apparent from the following detailed description and drawings.

DETAILED DESCRIPTION 
Turning now in greater detail to the drawings, there is shown in FIG. 1 an 
exploded cross-section of the fundamental elements of the preferred 
embodiment of the invention. An inverted-bucket tappet 1 is formed with an 
extension 2 integrally joined with the interior bottom. A hemispherical 
cavity 3 is formed within the housing 2, with its center concentric with 
the axis of the tappet. The large open end 3' of the hemispherical cavity 
opens towards the open bottom end of the cylindrical skirt 1' of the 
tappet. An optional circular groove 4 is formed close to the open bottom 
end 3'. An optional flat cavity 1C is formed on the upper or top portion 
of the tappet 1. A small hole 5 is disposed coaxially in the center of the 
tappet to establish direct communication between the top cavity 1C and the 
hemispherical cavity 3. A shim 6, such as the illustrated stepped or 
double-diameter thick shim, can be disposed in the cavity 1C as explained 
in another of applicant's patent applications, U.S. Ser. No. 08/352,943, 
filed Dec. 9, 1994, now U.S. Pat. No. 5,445,119 and assigned to the 
assignee of this invention and hereby incorporated by reference. 
A conventional thinner, single diameter shim (not shown) can also be 
installed in cavity 1C in lieu of the stepped shim 6 as shown. An optional 
orifice 5' may be disposed axially in the center of either of the shims. A 
pivot member 8 which is formed as a portion of a sphere has a flat bottom 
surface 9, is disposed snugly inside the hemispherical cavity 3 so that 
the hemispherical surfaces of each engage one another. This permits free 
but limited pivotal or rocking motion in the fashion of a ball and socket 
joint. To positively maintain member 8 in cavity 3, a snap ring 7 may 
optionally be disposed within groove 4 located near the open end of the 
hemispherical cavity 3. Alternately, a conventional rubber "0" ring, or 
any other kind or spring retainer (neither shown) can optionally be 
installed in lieu of the snap ring 7. A portion of a valve is shown in 
FIG. 1. Specifically, the upper end portion or tip 52' of an elongated 
valve stem 52 of the valve contacts the flat bottom end surface 9 of the 
rotular sliding pivot 8. Thus, forces on tappet 1 are transmitted to the 
valve through the pivot 8. In a contemplated alternate design of the 
rotular sliding pivot mechanism (not shown), an elongated cylindrical body 
extends between a hemispherically configured end surface, alike end 
surface 8, and a flat end surface, alike surface 9. 
As shown in FIG. 1, the elongated valve stem portion 52 has an axis 53 
which can be angulated with respect to the longitudinal axis "Z" of the 
tappet 1. The force transmitting means between tappet and valve 
accommodating this arrangement is the essence of the subject patent 
application. In addition, the center or contact point of the upper end 
portion or tip 52' of the valve stem 52, may optionally be offset from the 
axial center of the flat bottom portion of the rotular sliding pivot 8. 
In operation, the body of the tappet reciprocates within a cylindrical 
guide (not shown) formed either as an integral part of the cylinder head 
(not shown) or of a separate member fixedly attached to the cylinder head 
(also not shown); guided by the cylindrical skirt 1' of the tappet 1. The 
downward reciprocating stroke of the tappet 1 follows the arcuate motion 
of an associated cam lobe of a camshaft (neither shown) as it contacts the 
top surface 6' of the shim 6. This downward motion of the tappet is 
transmitted to the valve through the ball and socket joint 3, 8, and 9. 
The associated valve is opened as a result. As the tappet and the valve 
are displaced from a seated or closed position (seated-valve position), 
the flat bottom surface 9 of the rotular sliding pivot 8 slides sideways 
or laterally with respect to the end portion or flat tip 52' of the valve 
stem 52 due to the angularity between the respective axis 53 and "Z" of 
the valve stem 52' and the tappet 1. As is known in the engine art, the 
valve is returned to the seated or closed position by the action of a 
spring (not shown) which engages a spring retainer (also not shown) 
fixedly attached to the valve stem by locks or keepers (also not shown). 
The closing action of the valve results from the release of the compressed 
spring, and this also moves the tappet and rotular mechanism upwardly. 
When the valve is seated or closed, a gap or valve lash is created between 
the top surface 6' of shim 6 and the base circle of the cam lobe (not 
shown). 
A system is described above for providing a mechanical lash-setting system 
in which valve lash clearance is intentionally created, by design, to 
compensate for thermal expansions and contractions of the valve train and 
to accommodate wear of the different elements. To compensate for 
manufacturing tolerances of the different machined elements, one element 
in the axial line of the valve stem may be made with differing but 
controlled dimensions. This selectively dimensioned element is used to 
establish a desired valve lash during engine assembly and also during 
service. This compensate for wear, remachining of the valve seat, 
introduction of replacement parts, etc. 
For a mass-produced engines having the subject valve mechanism, it is 
convenient to select shim 6 for the element used in varying thickness to 
establish valve lash. Alternately, the thickness of the rotular sliding 
pivot 8 may be varied. 
For lubricating the rotular sliding pivot 8, holes 5 and 5' may be provided 
to direct oil to the rotular sliding pivot 8 inside cavity 3. When a valve 
is in its seated mode of operation, oil normally found adjacent the upper 
end of the tappets settles in a film over the top surface 6' of shim 6. 
The open gap or lash space between the lobe and the surface 6' allows oil 
to fill holes 5, 5' by gravity. As the camshaft rotates, the cam lobe 
closes the lash space and forces a small amount of oil down through the 
holes 5 and 5'. This maintains a flow of oil into the rotular cavity. 
In a longitudinal plane of the engine, the angularity between the axis 53 
of the tappet and the axis "Z" of the valve stem 52' may be used as a 
design element to allow more design freedom on where to locate the 
different elements of a valve train. Also, the placement of valve train 
components in the sideways or transversal plane of the engine can be 
useful as a design tool. Particularly for multi-valve engines, these new 
design freedoms made possible by the subject rotular mechanism can create 
increased space at the center of the cylinder head between a cylinder's 
valves and other valve components, and their respective ports. This 
increased space permits installation of conventional diesel injectors or 
precombustion chambers, in the case of diesel engines. In open-chamber 
(DI) diesel engine design, the increased space allows increased cooling 
passage volume to cool the operating tip of the injector at the combustion 
chamber. 
Without the increased space afforded by the subject valve train design, 
conventionally sized spark plugs often could not be used in small gasoline 
engines having four, five or six-valved combustion chambers. With 
increased space, additional water cooling passage volume can also be 
provided near the hot end portion of the spark plug. This allows use of 
hotter spark plugs and reduces detonation tendencies. Additionally, more 
space can be created within the perimeter of the combustion chamber, 
allowing use of larger valves or larger bridges between valves, or a 
combination thereof. Larger valves normally increase air flow and exhaust 
flow which usually increases power output and may lower fuel consumption 
and emissions. Because the valves open in a radial inward direction away 
from the cylinder wall characterized by a very even opening gap about the 
entire perimeter of the valve head, their is a minimum of back or side 
shrouding than with other valve arrangements which further increasing air 
flow. 
One further advantage inherent with increased space created by the subject 
valve train arrangement and design is improved cooling of the cylinder 
head and hence the valves in the valve bridge area between valves, 
particularly between a pair of exhaust valves. The increased space permits 
larger water cooling passages and use of bigger and stronger cores for 
casting cylinder heads. This advantage will be explained later in 
reference to FIG. 6. 
With respect to combustion benefits, the subject valve train provides a 
relatively smooth upper combustion chamber surface, either in a preferred 
hemispherical shape or in configuration of a frustum of a cone. The 
improved combustion is a benefit which will be discussed below. 
In FIG. 2, a cross-section of an internal combustion engine 10 is shown 
including an engine block 12 in which a plurality of cylinder bores 14 are 
formed, only one of which is visible. A piston 16 is mounted for 
reciprocating linear motion in each of the cylinders 14. As is well known 
in the engine art, the pistons are operatively coupled to a crankshaft 
(not shown) by a connecting rod (not shown) and piston pin (not shown). 
A cylinder head 20 is mounted atop engine block 10 and is secured thereon 
by a plurality of elongated threaded fasteners 24. The cylinder head 20 is 
formed with concave recesses to form substantially hemispherical 
combustion chambers 26. One recess is aligned with each cylinder bore 14 
and each recess is substantially the same diameter as the cylinder bore. 
The hemispherical concave wall 28 formed by a recess in the cylinder head 
cooperates with the upper convex surface 30 of piston 16 and with the side 
wall of the cylinder bore 14 to define an expandable and contractible 
combustion chamber. 
As best illustrated in FIG. 2, the cylinder head 20 also has air intake and 
gas exhaust passages 34, 36, located, respectively, on either side of a 
longitudinally extending mid-plane (normal to the plane of FIG. 2) which 
plane includes axis L of the cylinder bore 14. Intake passage 34 leads 
from a flanged entrance 40 at one side of the cylinder head to an annular 
inlet opening 42 leading into combustion chamber 26. The peripheral edge 
defining inlet opening 42 has an inwardly tapered configuration forming an 
annular sealing seat 46. Seat 46 is engaged by a corresponding and like 
configured outer annular edge 47 of and enlarged head portion 48 of an 
intake valve 50. It should be noted that the intake valve 50 is one of a 
pair of identical intake valves for the combustion chamber 26 and that the 
other intake valve is located behind valve 50 in FIG. 2 and thus is not 
visible. The previous and following detailed description of valve 50 is 
applicable to the second intake valve. 
Intake valve 50 has an elongated stem portion 52 that extends upwardly from 
its head portion 48. As explained previously, the elongated stem portion 
52 has an axis 53 extending from origin point P located below 
hemispherical surface 28, past hemispherical recess or surface 28, through 
a guide sleeve 54 secured to cylinder head 20 and terminates at tip 52'. 
Note that in FIGS. 2 and 6 that axis 53 is angulated from the vertical as 
represented by axis L. The flat upper end portion or tip 52' abuts the 
flat end surface 9 of the rotular sliding pivot 8 as previously explained 
(see FIG. 1). 
Referring specifically to FIG. 6, the tappet 1 is partly defined by 
cylindrical skirt 1' which is reciprocally mounted in a bore 64 formed in 
a support structure 71 which is attached to the cylinder head 20. Bore 64 
guides movement of tappet 1 in a linear movement along an axis 65 in 
response to the action of the engine's camshaft 66. Specifically, as the 
camshaft is rotated, a cam lobe 68 slides over the upper surface of shim 6 
or the top surface of the tappet 1, if shims are not employed. As best 
shown in FIG.2, the camshaft 66 is mounted for rotation in journals 67, 69 
formed in a laterally extending portion of structure 71 which also 
supports the tappets. As shown in FIG. 2, structure 71 is secured to the 
cylinder head 20 by threaded fasteners 74. 
As best shown in FIG. 6, the movement of cam lobe 68 across the upper 
surface of the tappet 1 causes downward displacement of the tappet along 
the axis 65. This movement compresses helical valve spring 72 shown in 
FIG. 2. Spring 72 extends between the upper surface of the cylinder head 
20 and a retainer disc 59 which is secured to the valve stem 52 by locks 
60. The actuation force causing valve opening moves tappet 1 along 
vertical axis 65. This actuation force is transmitted through the tappet's 
rotular sliding pivot mechanism 8 to valve stem 52. The resultant force 
transmission produces an axially directed force on the valve stem 52 to 
produce movement along the valve stem's axis 53. This movement moves the 
valve head 48 from its seat 46 to a more opened operative position so that 
air will pass from intake passage 34 into the combustion chamber 26. 
As the camshaft lobe 68 slides past the top surface of the tappet 1, the 
compressed valve spring 72 releases energy to move valve 50 back toward 
its closed operative position in which the valve head 48 is seated with 
seat 46 to end intake air flow to the combustion chamber. 
As best illustrated in FIGS. 2 and 3, the generally flat end surface 48' of 
the valve's enlarged head portion 48 lies substantially tangently to the 
hemispherical upper surface 28 of the combustion chamber 26. This produces 
a desirable smooth and even-walled combustion chamber. Undesirable pockets 
and crevices in the combustion chamber are avoided and this promotes 
increased burn efficiency of the air/fuel mixture which results in a 
cleaner engine. 
Referring now to FIG. 6, the transverse outer faces 78 of cam lobes 68 
extend parallel to the rotational axis 80 of cam shaft 66. Resultantly, 
the contact between face 78 and the surface of shim 6 extends evenly there 
across. The contact between surfaces 6 and 78 generates tappet movement 
along axis 65 evenly without undue wear at any particular points on the 
shim surface 6 or tappet face. 
FIG. 5 is a top planar view of the engine cylinder arrangement which shows 
the engine's longitudinal axis and plane L normal to the surface of the 
drawing. Section lines 6--6 in FIG. 5 indicate the direction of view in 
FIG. 6 which shows camshaft axis 80 which is also parallel to longitudinal 
engine axis and plane L. FIG. 6 is shown devoid of non-essential elements 
for clarity to better reveal the action between cam lobes 66 and tappets 
1. The cross-hatched section shows portions of the lower deck 167 of the 
cylinder head 20 and also portions of structure 71. Two intake ports or 
passages 169 are shown and two windows 169W in outline are revealed as the 
intersection of the passages at the outside flange where the intake 
manifold attaches. The line O/W diagrammatically indicates the approximate 
location of the cylinder head's oil shelf or where the separation is of 
the portion of the cylinder head lubricated by oil (space above line OW) 
from the portion of the head cooled by water jackets or passages (space 
below the line OW). The view reveals the exceptionally good water cooling 
provided for the bridge area located between the two passages or ports 
167, 169. This can be appreciated by observing that the width of the 
bridge face in the combustion chamber labeled as "B" is about 9 mm, 
whereas the width of the jacket water labeled as "BW" is 7 mm, or closely 
the same width. With the subject valve train design, this occurs because 
the ports 167, 169 diverge from each other at double the angle that any 
one of the valves incline from the vertical. In the arrangements disclosed 
in the known prior art, if any pair of valves characterized by parallel 
stem portions created a 9 mm bridge therebetween, the ports or passages 
would have been artificially "bended" away from each other merely to 
obtain a 5 mm minimum core width between the valves. Resultantly, 3 mm of 
extra water passage or core width would be lost and bridge cooling would 
decrease along with air flow losses due to the required "bend" in the 
passages. Additionally, from a casting point of view, a sand core with a 
minimum radius of 3.5 mm which tapers outwards, is much stronger than a 
skinny and long one with minimum radius of 2.5 mm. 
Still referring to FIG. 6, in addition to intake valve 50, a corresponding 
intake valves 51 is seen, as was previously described. However, as is best 
shown in FIGS. 4 and 5, the two intake valves are disposed on different 
axes, 53 for valve 50 and 81 for valve 51. The axes 51, 81 diverge 
outwardly from one another and from a centerpoint P. Accordingly, the axis 
53 (and associated valve 50) and axis 81 (and associated valve 51) diverge 
outwardly from one another and are angled equally from the longitudinal 
and transversal planes L and T which extend through the engine as 
diagrammatically shown in FIG. 5. Lines 80 and 80' indicate the respective 
centerlines of the intake and exhaust camshafts. 
As seen in FIGS. 2, 4 and 5, in addition to intake valves 50 and 51 there 
are provided a pair of exhaust valves 84 and 86 to control the exhaust of 
gases from the engine cylinder. Valves 84, 86 have substantially the same 
construction as the intake valves 50 and 51 and their tappets, return 
springs and other constructional details are like those associated with 
the intake valves. It is seen that the exhaust valves are positioned on an 
opposite side of the longitudinal plane L and are opposed in the 
transverse direction to the intake valves 50, 51. 
As with the intake valves, the exhaust valves are moved to a more opened 
position by cam lobes 94 of camshaft 88 and are returned to their closed 
positions by valve closure springs 72' similar to helical spring 72 
associated with the intake valve. 
Similar to intake camshaft 66, the exhaust camshaft 88 has a plurality of 
cam lobes 94 which are responsible for opening the exhaust valves 84 and 
86. The exhaust valves 84, 86 extend along radially and outwardly 
diverging axes 95, 96 as best shown in FIG. 5. More particularly, the axes 
95, 96 of exhaust valves 84, 86 radiate from point P as shown in FIG. 2 
and extend radially through hemispherical chamber wall 28 and terminate at 
an upper end portion or tip. The tip 84' of exhaust valve 84 is best shown 
in FIG. 4. With this arrangement, the enlarged valve head portions 84", 
86" of valves 84, 86 are tangentially to the hemispherical surface 28 of 
the combustion chamber's upper wall. The stem portions of the valves 85, 
87 diverge outwardly from one another and with respect to both the 
longitudinal and transversal planes L and T. Preferably, the angle of 
inclination of all the valves are equal with respect to the horizontal and 
transversal planes and the axis of their stem portions converge at a 
common point P along and low in the centerline of the cylinder bore 14. 
This may not be clear in FIG. 4 because it is an isometric rendition. 
FIG. 4 depicts a divided chamber diesel engine with each valve angled 
outwardly from the combustion chamber with respect to both the 
longitudinal and transversal planes L and T, as shown in FIG. 4, a space 
shaped generally as a truncated cone 100 is provided. This space is 
advantageously employed so that a fuel injector 103 and a prechamber 
assembly 104 can be readily and centrally positioned directly adjacent and 
very close to combustion chamber 26 for improved engine operation. Due to 
the described valve train arrangement and construction, space 100 is much 
increased as compared to previous cylinder heads. The additional space 
desirably provides clearance for a glow plug 106 shown positioned to enter 
the precombustion chamber 104. Glow plug 106 approaches the chamber 104 
through the large bridge formed between the two intake passages or ports 
(not detailed) of the intake valves 50, 51. 
The following characterizes a proposed divided chamber diesel engine shown 
in FIG. 4. It has a 84.5 mm cylinder bore diameter and a 98 mm stroke, 
resulting in a cylinder displacement of 549.6 cubic centimeters. The 
rendition allows a Nominal Compression Ratio of about 20.0:1. The engine, 
with only about 25% of the total clearance volume in prechamber 104, 
features a reduced prechamber internal surface and therefore decreased 
heat losses therefrom. The prechamber may be similar to one disclosed in 
U.S. Pat. No. 5,392,744, which issued Feb. 28, 1995 to the applicant of 
this invention. The prechamber would preferably have four large, tapered 
transfer passages 107 (only two visible) which would decrease pumping work 
required for flow between the interior of the prechamber and the 
combustion chamber. Due to the close mating of valve heads with the 
hemispherical surface of the combustion chamber shown in FIG. 3, there is 
no appreciable crevice space or volume and there is sufficient clearance 
volume available to create relatively deep valve cutouts or pockets 108 in 
the top surface of pistons 16. These pockets a also serve as combustion 
pockets on the top of the pistons 16. On the intake passage side of the 
cylinder head, the deep pockets allow the intake valves to be opened or 
lifted about 4.7 mm when the piston and valve heads are at their closest 
spacing during intake and exhaust overlap. There is still sufficient 
clearance so that valves and piston will not contact one another. This 
relatively large intake valve lift during the overlap period of operation 
is achieved by advancing the intake camshaft a total of 50 crank angle 
degrees through a variable intake valve mechanism (not shown). The 50 
advance degrees permits the intake valves to be closed, effectively, at 23 
degrees ABDC. This results in an effective compression ratio of 18.7:1. 
This approach assures an efficient starting of the engine even at 0 
degrees F within two seconds, without a prior pre-heat of the engine. 
The above described functional results including improved combustion, are 
made possible by the subject valve train lay-out and construction which 
provides greatly increased space in the central portion of the cylinder 
head above each combustion chamber. The increased space permits use of a 
precombustion chamber with a desirable short flow path. Also, the 
previously described flush positioning of the valve heads along the 
surface 28 of the combustion chamber 26 effectively eliminates wasted 
volumes or crevices, and minimizes heat losses. 
FIG. 4A illustrates a spark-ignited and homogeneous charged version of the 
same basic cylinder head and valve train structure as shown in FIG. 4. The 
engine essentially has an identical valve train and the piston 16' has a 
basic Heron type bowl chamber 108' formed on its top surface portion. The 
injector 103 and precombustion chamber 105 of FIG. 4 have been replaced by 
spark plug 103'. 
As is well known, the sphere offers the lowest surface to volume ratio. 
Thus, a hemispherical combustion chamber minimizes the surface area of the 
combustion chamber in relation to its volume. This reduces heat losses to 
the coolant per mass or volume of fuel burned to improve thermodynamic 
efficiency. Also, the extent of cold-wall surface is minimized and 
resultantly the amount of fuel contacting the cold surfaces is reduced. 
Also, this reduces the degree of flame quench which is caused by contact 
with cold surfaces. It is known that hydrocarbon products adhere to cool 
surfaces and are later evacuated during the exhaust portion of the cycle. 
Thus, hydrocarbon emissions are minimized by the subject valve train and 
combustion chamber. 
In diesel engines, heat transfer from the combustion chamber is detrimental 
when starting a cold engine because heat losses reduce compression 
temperatures and a diesel engine initiates combustion by rising the 
temperature of the compressed air. In combination with the splaying of the 
valves, which allows larger valves and more air flow, it should be 
appreciated that the subject valve train and cylinder head construction 
offers the greatest degree of utilization of the cylinder head surface for 
desirable purposes such as larger valves and bridges while minimizes 
negatives such as heat loss. Also, it provides a very significant increase 
in exhaust valve and bridge cooling. 
Turning now to FIG. 7, a modification is shown of the tappet and rotular 
sliding pivot mechanism. The configuration of tappet 162 is similar to 
tappet 1 of FIGS. 1 and 2. Tappet 162 has a recessed top end which 
supports a shim member 164. To establish correct valve lash for valve 150, 
a shim having a particular thickness is selected from a set of shims of 
differing thickness. Optionally, the tappet may be shimless with the 
tappet's top surface establishing a solid surface for contact by a cam 
lobe. Alternately, the lash adjustment can be performed by selecting a 
correctly thickness sized rotular sliding pivot mechanism. In FIG. 7 a 
modified mechanism is shown including a member 163 with upper flat end 
surface 163' which is slidable along an abutting flat surface 162' of 
tappet 162 and with a hemispherical concavity 162" formed in an opposite 
end. A rounded end portion 152' of the valve's upper end portion or tip of 
the valve stem 152 mates with the concavity 162" for accommodating 
angulation between the axis of tappet 162 and the axis of stem portion 
152. In this embodiment, both tappet 162 and sliding member 163 need not 
be located concentrically because the outside diameter of the member 163 
is significantly smaller than the inside diameter of tappet 162. 
Consequently, member 163 can slide sideways along tappet surface 162'. By 
allowing the tappet to be located offset centrally from the centerline of 
the valve, design flexibility is enhanced which may be crucial in the 
successful design of the engine. 
In FIG. 8,an additional embodiment is shown in which the convex 
hemispherical configuration 263' which corresponds to the rounded 
hemispherical end 152' in FIG. 7 is formed on the slidable element or 
member 263. The concavity 268' corresponding to the concavity 162" in FIG. 
7 is formed in a portion of a headed socket member 268 which is mounted on 
the upper end of the valve stem portion 152. The rotular sliding pivot 263 
has a flat end surface 263" which is slidably supported against interior 
flat surface 262' of the tappet. As in the embodiment shown in FIG. 7, the 
diameter of member 263 is significantly smaller than the diameter of the 
surface 262' to permit centrally offset positioning and significant 
sliding motion therebeween. The convex hemispherical formation 263' on an 
opposite end of the rotular sliding pivot 263 may also be centrally offset 
for enhanced design freedom. Valve lash adjustments can be achieved by 
varying the axial thickness of either one, or the combination of the two 
elements 263 and 268. 
FIG. 8A is a similar to the embodiment shown in FIG. 8 and thus is a 
derivative. In this embodiment, a tappet 362 has an alternate shimless 
design with an interior flat surface 362'. A slidable member 363 with a 
flat upper end surface 363' is mounted against the downwardly facing 
surface 362'. Member 363 also supports a hemispherical portion 363" on an 
opposite end from end surface 363'. A headed socket member 364 faces the 
hemispherical portion 363" and defines a hemispherical concavity 366 
corresponding to the concavity 268" in FIG. 8. The hemispherical portions 
363" and 366 mate with one another to accommodate differences in 
angularity between the axis of tappet 362 and the axis of valve stem 
portion 350. Socket member 364 also has an internal threaded bore adapted 
to thread over and about the threaded upper end portion or tip 352 of 
valve stem portion 350. The lower, exterior surface of member 368 is 
formed with a hexagonal configuration 368' so that the member 368 can be 
turned with a tool such as a wrench to adjust for valve lash. The selected 
position is locked in a desirable place with a lock nut 366. With this 
design, lash adjustments can be made with common wrenches and feeler 
gages, very quickly, without disrupting the assembly. A subassembly of 
members 363 and 368 can be achieved by rolling the edge 364' of socket 
member 364 over the spherical end 363". 
In FIG. 9, a portion of a cylinder head 500 is shown in another embodiment 
wherein the cylinder head supports intake valve 550 and other ancillary 
valve train elements such as valve guide 54, coil spring 72, spring disc 
59, and retainers 60. These elements are the same as the elements in FIG. 
2 and are numbered the same. Valve 550 has an enlarged head portion 552, 
an elongated stem portion 554, and an upper end portion or tip 556. Above 
valve tip 556, an inverted-bucket type tappet 501 is shown which is 
similar to tappet 1 as shown in FIGS. 1 and 2. Likewise, the concavity 
501' formed in tappet 501 is similar to the concavity 3 of tappet 1. 
Likewise, the rotular sliding pivot mechanism 502 is similar to the 
mechanism shown associated with tappet 1. However, unlike the direct 
acting overhead camshaft shown in FIG. 2, the camshaft 566 in FIG. 9 acts 
directly upon a finger follower 560 rather than on the tappet. The 
rightward end portion 563 of follower 560 is supported on an end of a 
hydraulic lash compensator 561. Both of these components 560, 561 are 
known in the art of present day engines. Finger follower 560 supports an 
anti-friction roller element 560' at its midportion and generally extends 
in a transverse plane of the engine. The axis of the roller element 560' 
extends parallel to the axis of camshaft 566, with line contact between 
the periphery of the roller 560' and the cam lobe 568 along a line (not 
shown) parallel to the axis of the camshaft. Since lash compensation is 
hydraulic, no shims of varying thickness are required, but one (not shown) 
may be provided as a wear pad. The leftward end of the finger follower 
operationally engages the top of the inverted-bucket tappet 501. 
Reference is made to FIG. 9A showing a side elevational view of the valve 
mechanism along sight line 9A--9A of FIG. 9. This side view reveals a 
grooved formation on the bottom 505 of the left end portion of finger 
follower 560. The groove 505' is shown engaging and about a cylindrical 
protrusion or tab 501' which integrally extends upward from the central 
portion of the tappet's top surface. Alternately, if a shim is used, the 
tab would be integral with the shim. The arrangement with groove 505' 
straddling tab 501' secures the end portion of finger follower 560 and 
inhibits rotation about a vertical axis "V" at the pivoted rightward end 
563. Thus, follower 560 is prevented from being removed from the top of 
the tappet and a straight line contact 578 is maintained between cam lobe 
568 and the roller element 560'. 
In FIGS. 10 and 11, a cam mechanism for simultaneously actuating multiple 
tappets together is shown. Large truck, industrial and marine engines have 
used a similar arrangement for a number of years. An in-block mounted 
camshaft 666 or a camshaft in the cylinder head rotates cam lobes 666' 
which engage a surface 659' of a conventional tappet 659. The action 
caused by the cam lobe moves a push rods 659" which in turn pushes against 
the rightward end 660' of a rocker arms 660. Rocker arm 660 is pivotally 
mounted upon a shaft as shown. The leftward end portion 660" engages a 
central portion of a T-shaped bridge member 661. Member 661 has a central 
portion with a generally vertical bore 661'. The member 661 is supported 
by an elongated dowel member 603 which is attached at a lower end to the 
cylinder head and extends upward therefrom. This permits the member 661 to 
move upwards and downwards along the dowel member 603. 
Both end portions of the T-shaped bridge member 661 support foot devices 
605 which engage a respective tappet 601. The rightward foot device 605R 
is attached to the rightward end portion of member 661 by a short axle 
606. The leftward foot device 605L is attached to the leftward end portion 
of member 661 by a threaded shaft 608 and lock nut 609. To prevent 
rotation of the member 661 about the axis of dowel 603, at least one of 
the two foot devices 605 is mounted in a depression 607 formed in the top 
surface of a corresponding tappet 601. 
Alternatively, as shown in FIG. 11A, rotation of the T-shaped bridge member 
661 about the dowel 603 can be prevented by forming a groove 605" in the 
bottom surface 605' of one of the end portions or arms. Preferably the one 
leg which has no lash adjustment function is selected. The groove 605" is 
formed along the horizontal axis of the member 661 which corresponds to a 
direction parallel to the engine's transverse plane. The groove 605' abuts 
and engages a cylindrical protrusion or tab 601' which is extends from the 
upper surface of the tappet 601 or alternately, from a shim or wear pad. 
FIG. 10 shows in an elevational end sectioned view the inclination from the 
vertical of a pair of valves (intake or exhaust) in a transverse plane of 
the engine. FIG. 11 is a side elevational view along sight line 11--11 of 
FIG. 10. It shows the inclination from the vertical of one of the valves 
in a longitudinal plane of the engine. The angle of inclination of the 
valves in either plane is the same or very close to the same. 
ENGINES WITH MORE OR LESS THAN FOUR VALVE PER CYLINDER 
While previously described embodiments of this invention concerned engines 
with two intake valves and two exhaust valves, the subject valve train 
arrangement and configuration can be profitably employed with greater or 
lesser numbers of intake and exhaust valves than four. For example, in 
FIG. 13, three intake and three exhaust valves are employed. The enlarged 
head portions 800', 802', 808', 814', 816', and 818' of the valves 800, 
802, 808, 814, 816, and 818 are within the periphery of the hemispherical 
combustion chamber shown by the circle "C" in FIG. 13. 
The two exhaust valves 800, 802 angulate from the vertical in both the 
engine's longitudinal and transverse planes L, T. They are engaged, 
respectively, by tappets 804, 806 mounted to move along a vertical axis as 
with the valves in the previous four valve engines. Tappets 804, 806 have 
rotular sliding pivot mechanisms. The center exhaust valve 808 angulates 
outwardly from the vertical only in transverse plane T of the engine and 
not in a longitudinal plane. Thus, its tappet 810 is mounted to move along 
a different axis than tappets 804, 806. Tappet 810 also has a rotular 
sliding pivot mechanism. 
The same arrangement of the valves and tappets are used on the intake side 
of the cylinder head for intake valves 814, 816 and 818. Therefore, the 
explanation of angulation and mounting of tappets is similar and will not 
be repeated. Opening of the exhaust and intake valves are operated by the 
cam lobes of associated exhaust and intake camshafts 822, 824, as is shown 
in FIG. 13. With this construction as an example, it can be appreciated 
that an even larger number of valves with different angularities for each 
set of equal function valves may be operated by a single camshaft. With 
the valve train design of this application, increased central space 
between the valves and directly above the combustion chamber is available 
so that standard size spark plugs, prechambers and fuel injectors can be 
used even on smaller engines. 
The orientation of the centers of all tappets on the same line along the 
contacts with the camshaft lobes may not be readily obvious from FIG. 13 
because this is an isometric view. However, such alignment and disposition 
is required for this design to operate desirably. From FIG. 13 it should 
be appreciated that the size or diameter of tappet 810 on the exhaust side 
and 830 on the intake side is greater than the remainder of tappets 804, 
806 on the exhaust side and 834, 836 on the intake side. The greater 
diameter of tappets 810, 830 is needed due to the fact that tappets 810, 
830 are offset on the transverse plane of the cylinder and engine and from 
the axial centerline of the camshaft and must be made larger to prevent 
the camshaft lobe from excessively loading the edge of the tappet. 
While several embodiments of the invention have been shown and described, 
other embodiments are contemplated and will become apparent to those 
skilled in the art after studying this application. Accordingly, the 
invention should not be limited to only that which is shown and described 
but by the following claims.