Patent Application
20110083624
The present invention relates to internal combustion engines, and more particularly to the cylinder heads and components thereof.
Gaseous emissions from internal combustion engines, notably oxides of nitrogen, which may be referred to as “NOx”, may be reduced by reducing engine combustion temperature. For diesel engines, a method which may be utilized for reducing combustion temperature is to add exhaust gas recirculation (“EGR”) to the charge air. As the EGR displaces air from the cylinder, the air and added EGR must be delivered to the engine at a higher pressure to maintain engine power, which may be achieved by pressure charging the engine. One consequence of the pressure charging is that the engine cylinder pressures increase to a point where the integrity of conventional cylinder head structure may be inadequate, resulting in cylinder head fatigue, deflection and other deformation, as well as cylinder head gas and coolant leaks. In light of the above, what is needed is an engine with a cylinder head which overcomes the aforementioned deficiencies in the art.
The inventions disclosed herein provide means of increasing the cylinder pressure capability and mechanical integrity of an engine cylinder head. This may be achieved by an optimization of the cylinder head design for structural stiffness, as well as accommodation of thermal and mechanical loads placed on the cylinder head, through a unique combination of design features. Such design features include various elements of the cylinder head such as the ports (valve/valve seats), decks, coolant jackets, mounting bolt pattern, sleeves for fuel injectors or ignitors, side walls and interior walls, as well as any other elements of the cylinder head disclosed herein.
According to one aspect of the invention, a cylinder head for an engine may be provided comprising a valve seat arrangement for a cylinder of the engine, with the valve seat arrangement comprising at least two inlet valve seats on an inlet valve seat axis at an angle in a range of 30 to 60 degrees to a major axis of the engine, and at least two exhaust valve seats on an exhaust valve seat axis at an angle in a range of 30 to 60 degrees to the major axis of the engine; an upper deck, an intermediate deck and a fire deck; an upper coolant jacket between the upper deck and the intermediate deck; a lower coolant jacket between the intermediate deck and the fire deck; and a cavity to accommodate a fuel injector or an ignitor therein, with the cavity defined by a monolithic wall connecting the fire deck with the upper deck. From this combination of features, as well as other features herein, increased stiffness of the cylinder head may be realized, which may effectively inhibit undesirable stressing, deflecting and otherwise deforming of the cylinder head fire deck or other portions thereof.
In preferred embodiments, the upper deck thickness and fire deck thickness may be greater than the intermediate deck thickness. For example, the upper deck thickness and fire deck thickness may be in a range of 150% to 300% of the intermediate deck thickness.
In preferred embodiments, the upper coolant jacket may comprise a half coolant jacket, and the half coolant jacket may be located on an exhaust side of the cylinder head.
In preferred embodiments, the lower coolant jacket may comprise a full coolant jacket, and more preferably a cross-flow coolant jacket which may provide a coolant path arranged for a coolant to flow through the cylinder head perpendicular to a major axis of the engine.
In preferred embodiments, at least one of the upper coolant jacket and the lower coolant jacket may be in fluid communication with an external coolant manifold.
In preferred embodiments, the cavity to accommodate the fuel injector or the ignitor may be in fluid communication with at least one of the upper coolant jacket and the lower coolant jacket, and the monolithic wall connecting the fire deck with the upper deck may be cylindrical. The monolithic wall connecting the fire deck with the upper deck may be arranged to support the fire deck against a deflection thereof by transmitting a mechanical load introduced on a flame face of the fire deck to the upper deck.
According to another aspect of the invention, a cylinder head for an engine may be provided comprising a monolithic structure forming an upper deck, an intermediate deck, a fire deck, a lower coolant jacket located between the fire deck and the intermediate deck, an upper coolant jacket located between the intermediate deck and the upper deck and a cavity to accommodate a fuel injector or an ignitor therein, with the cavity defined by a wall connecting the fire deck with the upper deck.
In preferred embodiments, the upper deck thickness and fire deck thickness may be greater than the intermediate deck thickness. For example, the upper deck thickness and fire deck thickness may be in a range of 150% to 300% of the intermediate deck thickness.
In preferred embodiments, the lower coolant jacket located between the fire deck and the intermediate deck may comprise a full coolant jacket, and more preferably a cross-flow coolant jacket which may provide a coolant path arranged for a coolant to flow through the cylinder head perpendicular to a major axis of the engine.
In preferred embodiments, the upper coolant jacket located between the intermediate deck and the upper deck may comprise a half coolant jacket, and the half coolant jacket may be located on an exhaust side of the cylinder head.
In preferred embodiments, at least one of the lower coolant jacket and the upper coolant jacket may be in fluid communication with an external coolant manifold.
In preferred embodiments, the cavity to accommodate the fuel injector or the ignitor may be in fluid communication with at least one of the lower coolant jacket and the upper coolant jacket, and the wall connecting the fire deck with the upper deck may be cylindrical. The wall connecting the fire deck with the upper deck may be arranged to support the fire deck against a deflection thereof by transmitting a mechanical load introduced on a flame face of the fire deck to the upper deck.
According to another aspect of the invention, a method of increasing the stiffness of a cylinder head for an engine is provided, with the method comprising: providing a valve seat arrangement for a cylinder of the engine, the valve seat arrangement comprising at least two inlet valve seats on an inlet valve seat axis at an angle of 30 to 60 degrees to a major axis of the engine, and at least two exhaust valve seats on an exhaust valve seat axis at an angle of 30 to 60 degrees to the major axis of the engine; providing an upper deck, an intermediate deck and a fire deck; providing an upper coolant jacket between the upper deck and the intermediate deck; providing a lower coolant jacket between the intermediate deck and the fire deck; and providing a cavity to accommodate a fuel injector or an ignitor therein, the cavity defined by a monolithic wall connecting the fire deck with the upper deck.
According to another aspect of the invention, a cylinder head sleeve for a cylinder head of an engine may be provided comprising a sleeve first part and a sleeve second part, wherein the sleeve first part and the sleeve second part form a cavity to contain a fuel injector or an ignitor, and wherein the sleeve first part and the sleeve second part form a joint for the sleeve first part and the sleeve second part to move relative to each other. As a result, an expansion of a cylinder head assembly under thermal loading may be better accommodated, which may effectively inhibit undesirable stressing, deflecting and otherwise deforming of the cylinder head fire deck or other portions thereof. Furthermore undesirable stress, deflection and other deformation as a result of mechanical loading on the cylinder head assembly may also be inhibited.
In preferred embodiments, the sleeve first part and the sleeve second part may have overlapping cylindrical portions, and the sleeve second part may slide within the sleeve first part. A coolant seal may be located between the overlapping portions.
In preferred embodiments, the joint may provide a gap between a contact surface of the sleeve first part and a contact surface of the sleeve second part. The gap may be adjusted to change a distance between the contact surfaces of the sleeve first part and the sleeve second part. The contact surface of the sleeve first part and the contact surface of the sleeve second part may be preferably horizontal and parallel surfaces.
According to another aspect of the invention, a cylinder head assembly for an engine may be provided comprising a sleeve having a first part and a sleeve second part, wherein the sleeve first part and the sleeve second part form a cavity to contain a fuel injector or an ignitor, and wherein the sleeve first part and the sleeve second part form a joint for the sleeve first part and the sleeve second part to move relative to each other; and a cylinder head.
In preferred embodiments, the cylinder head may comprise an upper deck, and the sleeve first part may be connected with the upper deck, such as by a threaded engagement with the upper deck. The cylinder head may also comprise a lower deck, and the sleeve second part may be connected with the lower deck, such as by an interference fit with the lower deck. A coolant seal may be provided between the sleeve first part and the upper deck, another coolant seal may be provided between the sleeve second part and the lower deck, and another coolant seal may be provided between the sleeve first part and the sleeve second part.
In preferred embodiments, the sleeve may be removable from a cavity in the cylinder head. The cylinder head may comprise an upper deck, an intermediate deck and a lower deck, wherein a lower coolant jacket may be located between the fire deck and the intermediate deck, and an upper coolant jacket may be located between the intermediate deck and the upper deck. The lower coolant jacket located between the fire deck and the intermediate deck may comprise a full coolant jacket and more preferably a cross-flow coolant jacket which may provide a coolant path arranged for a coolant to flow through the cylinder head perpendicular to a major axis of the engine.
In preferred embodiments, the upper coolant jacket located between the intermediate deck and the upper deck may comprise a half coolant jacket, and the half coolant jacket may be located on an exhaust side of the cylinder head.
In preferred embodiments, at least one of the lower coolant jacket and the upper coolant jacket may be in fluid communication with an external coolant manifold.
In preferred embodiments, the cylinder head may comprise a cavity to accommodate the sleeve therein, with the cavity defined by a monolithic wall connecting the fire deck to the upper deck. The monolithic wall may be cylindrical.
In preferred embodiments, at least one of the lower coolant jacket and the upper coolant jacket may be in fluid communication with the cavity to accommodate the sleeve.
According to another aspect of the invention, a method of providing a cylinder head assembly may be provided comprising providing a sleeve for a fuel injector or an ignitor, the sleeve comprising a sleeve first part and a sleeve second part, wherein the sleeve first part and the sleeve second part form a cavity to contain the fuel injector or the ignitor, and wherein the sleeve first part and the sleeve second part form a joint for the sleeve first part and the sleeve second part to move relative to each other; placing a fuel injector or ignitor in the sleeve; providing a cylinder head comprising an upper deck, a fire deck and at least one coolant jacket located between the upper deck and the fire deck; connecting the sleeve first part to the upper deck of the cylinder head; and connecting the sleeve second part to the fire deck of the cylinder head.
In preferred embodiments, the steps of connecting the sleeve first part to the upper deck of the cylinder head and connecting the sleeve second part to the fire deck of the cylinder head may position the sleeve first part relative to the sleeve second part for the joint formed by the sleeve first part and the sleeve second part to be contracted. Consequently, upon use thereof, heating of the cylinder head assembly may expand the cylinder head assembly resulting in contracting of the joint formed by the sleeve first part and the sleeve second part. Contraction of the joint formed by the sleeve first part and the sleeve second part may also result from deflection of the fire deck.
Contracting the joint formed by the sleeve first part and the sleeve second part may further comprise contracting the joint until the joint is in a fully contracted state. In this manner, supporting a mechanical load introduced on a flame face of the fire deck through the joint to the upper deck of the cylinder head assembly may be better accommodated.
According to another aspect of the invention, a removable sleeve for fuel injector or ignitor is used in a cylinder head for at least one cylinder comprising two side walls; two end walls; three decks of preferred thickness; port walls of preferred thickness; a diamond shaped orientation of valve seats; a one haft upper coolant jacket; a lower coolant jacket and an external coolant manifold. In alternative embodiments, load bearing removable sleeve may be replaced or used in conjunction with load bearing cylindrical housing defining cavity for fuel injector or ignitor. From this combination of features increased stiffness of a cylinder head has been shown through analysis, which may effectively inhibit undesirable stressing, deflecting and otherwise deforming of the cylinder head fire deck or other portions thereof, and a cylinder head geometry may be provided which is optimized for structural stiffness and peak operating cylinder pressure capability.
The above-mentioned and other features of this disclosure, and the manner of attaining them, will become more apparent and better understood by reference to the following description of embodiments described herein taken in conjunction with the accompanying drawings, wherein:
It may be appreciated that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The embodiments herein may be capable of other embodiments and of being practiced or of being carried out in various ways. Also, it may be appreciated that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
In the context of this description, a cylinder head for an internal combustion engine is presented wherein the engine has a major or longitudinal axis taken through the length of the crankshaft, from front to rear ends of the engine when the engine is arranged as such in a vehicle. As presented herein, the major axis of the engine is horizontal and, for multi-cylinder applications, the cylinders may be laid out in an inline configuration along the major axis, with the cylinder head to cylinder block joint lying in a horizontal plane. “Vertical” orientation is at right angle to this horizontal plane. However, the invention applies equally well to any other engine orientation or configuration, and the inline configuration referenced herein is selected simply to establish a geometric orientation frame of reference. Having discussed the orientation of the engine, certain engine terminology will now be presented.
An “injector sleeve” or an “ignitor sleeve” is a containment in the cylinder head for the injector or ignitor, respectively, particularly to exclude oil, water and other fluid contaminates from the injector or ignitor. Use of the term “sleeve” herein without a designation should be understood to include either an injector sleeve or ignitor sleeve.
A “coolant jacket” of a cylinder head is that part of the cylinder head which contains a fluid coolant, such as a liquid mixture of water and anti-freeze, and distributes the coolant to the various parts of the cylinder head. The coolant jacket receives coolant from a coolant source at a lower temperature, such as a radiator, heats the coolant and transfers the coolant at a higher temperature to a coolant manifold which may be integral with the cylinder head or may be a separate part (external).
A “cylinder head deck” is a substantially horizontal plate element of a cylinder head structure. A cylinder head may have at least three decks, namely a top deck, which is uppermost and may be referred to as the upper deck; a fire deck, which is the bottom deck and overlies the cylinder block; and an intermediate deck which is between the fire and top decks. The coolant jacket is contained between these decks.
“Manifolds” conduct air into the inlet ports in the cylinder head, and allow exhaust gases to exit via the exhaust ports. The inlet manifold is generally connected to one vertical side face of the cylinder head along the major axis of the engine and the exhaust manifold is generally connected to the other (opposing) vertical side face of the cylinder head along the major axis of the engine; these faces are frequently known as the manifold faces.
The “end walls” of the cylinder head are the substantially vertical end faces at the longitudinal ends, generally front and rear, of the cylinder head which are perpendicular to the major axis and which connect with the vertical side faces of the cylinder head.
“Bolt bosses” are substantially vertical columns passing through the coolant jacket, to take the compressive load of the bolts or other fasteners which secure the cylinder head to the cylinder block, with a vertical central bore, such as a cylindrical drilling, to accommodate the bolts or other fasteners and fixing means.
“Thermal loading” of the cylinder head is due to the heat flow into the cylinder head structure. The heat flow increases the metal temperature of the cylinder head, giving rise to thermal stressing, due to material expansion effects, and the material properties of the cylinder head usually deteriorate as the metal temperatures increase, augmenting the displacements from thermal and mechanical loading.
“Mechanical loading” is generally considered loading of the cylinder head due to purely mechanical loads, such as the cylinder pressures, or bolt and other fastener tightening torques.
“Cross (coolant) flow” describes the manner in which coolant is arranged to flow from one longitudinal side of the cylinder head to the other longitudinal side, which is perpendicular to the major or longitudinal axis. For example, the coolant might flow from an entrance opening on the inlet manifold side of the cylinder head to an exit opening on the exhaust manifold side of the cylinder head where it is expelled therefrom, via the coolant jacket.
“Longitudinal (coolant) flow” describes the manner in which coolant is arranged to flow from one end of the cylinder head to the other end, which is parallel with the major or longitudinal axis. For example, the coolant might flow from the flywheel end of the cylinder head to the front end of the cylinder head via the lower coolant jacket.
Turning to the drawings,
With respect to the stiffness of cylinder head 10, the valve seat arrangement of
As shown in
Continuing with
Now with reference to
As shown in
Thus far, upper deck 72 and fire deck 38 are therefore connected by the structure of the six bolt bosses 62; four valve guide bosses 66; inlet port passages 40, 42; and exhaust port passages 44, 46. Furthermore, upper deck 72 and fire deck 38 are connected by a cylindrical housing 58 defining cavity 120 for fuel injector or ignitor 134 (shown in
Intermediate, or middle, deck 74, which connects with the two manifold side walls 80, 82, may be arranged to connect with the lower wall or floor portion 76 defining port passages 40, 42, 44, 46, and may partly form the floors of the passages to provide a transverse connection between the vertical wall portions 78 and the four outer vertical walls 80, 82, 84, 86 of the cylinder head 10. Upper deck 72 and fire deck 38 are preferably thicker than intermediate deck 74. More particularly, the upper deck 72 and fire deck 38 are usually substantially thicker than the intermediate deck 74, and can be, for example, from 150-300% as thick as the intermediate deck 74. Also, preferably the wall portions 70, 78 of port passages 40, 42, 44 and 46 have a thickness of 25-50% that of the fire deck thickness.
The cavity within the four side walls 80, 82, 84, 86 of cylinder head 10 between the upper deck 72 and fire deck 38 that is not occupied by the inlet port passages 40, 42; exhaust port passages 44, 46; bolt bosses 62; valve guide bosses 66; and housing 58 may be referred to as the coolant jacket 92, and in the case of the cylinder head 10 of
The coolant jackets 92a and 92b shown in
Turning to
Now, as shown by
With reference to
The removable single piece sleeve (not shown) is usually a swaged fit into the fire deck 38 and is sealed by a flexible polymer (elastomer) seal, such as an O ring, with the upper deck 72, the removable sleeve being maintained in its position by the clamping force on the injector onto the upper face 110 of the fire deck 38. Coolant can be arranged to enter the volume between wall 108 and the sleeve via openings 112, as well as exit into the upper coolant jacket 92a via other openings which are not shown.
As compared to the design of
Additionally, the rigid nature of the cast-in housing 58 resists the natural expansion of the fire deck 38 under thermal loads which can impose thermal strain. As shown, cavity 120 is completely isolated from coolant from coolant jackets 92a, 92b by wall 108 defining cast-in housing 58, and thus a separate sleeve is not required. However, a potential limitation of this structure is that coolant flow in to the critical valve bridge area above the fire deck 38 between the port passages 40, 42, 44, 46 and housing 58, may be restricted because of the bulkiness and close proximity of the lower end of the port passages and their close proximity to cast-in housing 58. A solution to this potential limitation is described in
Upper part 132a is mechanically connected with the upper deck 72 by means of threaded engagement between the threaded portion 142 of upper part 132a with mating threaded portion 154 of upper deck 72. Lower part 132b is mechanically connected with the fire deck 38 by means of an interference fit between nozzle opening 150 of cylinder head 10 and nozzle ring 152 of lower part 132b. Herein, an interference fit, also known as a press fit, is a connection between two parts which is achieved by friction after the parts are pushed together. Lower part 132b is also mechanically connected with the fire deck 38 by the force imposed on the injector or ignitor 134 by the injector clamp 136 which is rigidly connected to the cylinder head 10.
Upper part 132a and lower part 132b of sleeve 130 move by sliding relative to each other to change a length L of the sleeve 130. In particular, a load transfer joint is provided by upper part 132a and lower part 132b, which may be further described as a slip joint, which provides a dimensional gap G between the parts 132a and 132b as will now be discussed. Herein, a slip joint is a joint providing for dimensional change in a linear structure, which may be used to relieve stress and strain in the structure. The joint formed by upper part 132a and lower part 132b may further be described as a telescoping slip joint as the joint may extend and contract by the sliding of overlapping sections relative to each other.
As shown in
When sleeve 130 is installed in cylinder head 10, surfaces 138, 140 may be separated from each other by the thickness of the gap, which may have an order of magnitude of thousandths of an inch. During use, as cylinder head 10 is subjected to heat and associated thermal loads, the cylinder head 10 and sleeve 130 may dimensionally expand in a known manner. As sleeve 130 is subjected to thermal load, upper and lower parts 132a, 132b will expand such that the thickness of the gap G between contact surfaces 138, 140 may be expected to decrease. Thus, in this manner the gap G narrows to accommodate the natural expansion of parts 132a, 132b under thermal loading, which may effectively inhibit the expansion of upper and lower parts 132a, 132b from undesirably stressing and deflecting and otherwise deforming fire deck 38 towards the cylinder from the thermal expansion thereof.
Now, considering mechanical loads from the cylinder, and in particular any opposing loads from combustion, any remaining thickness of the gap G is preferably less than the maximum cylinder head deflection which may occur at the center of the cylinder head 10 (e.g. at injector/ignitor 134). Consequently, after a certain amount of fire deck 38 deformation in the form of deflection towards injector or ignitor 134, here predetermined by the remaining thickness of the gap G, the two sleeve surfaces 138, 140 butt against each other, thus providing a structural support to further mechanical loads and against further deflection of the fire deck associated with compression loads from the cylinder. Thus, the gap G can be decreased until contact surface 140 of the sleeve second part 132b contacts a contact surface 138 of the sleeve first part 132a. At this point, the joint of the sleeve 130 is in its fully contracted position as there is no gap G and can not contract further.
From the foregoing, sleeve 130 may provide a mechanism for reducing stress, deflection and other deformation of the fire deck 38 downwards (towards the cylinder) due to the thermal expansion of the sleeve 130 from above, as well as reducing stress and deflection of the fire deck 38 upwards (away from the cylinder) due to the mechanical loads of compression from below. Removable sleeve 130, therefore, may properly be considered to be a load bearing member.
Coolant may enter cavity 120 from the lower coolant jacket 92b via openings such as 146 and can exit to the upper coolant jacket 92a via openings such as 148. Coolant can be sealed from oil above the upper deck 72 via a seal provided between the upper deck 72 and sleeve upper part 132a, such as may be provided by a thread sealant 162, such a polytetrafluoroethylene (PTFE) tape, placed on screw thread 142 or a second o-ring installed directly below the threaded portion 142. With respect to the lower deck 38, coolant can be sealed from the cylinder below the lower deck 38 via a seal provided between the lower deck 38 and the sleeve upper part 132a, such as may be provided by the interference fit between the two parts.
In the foregoing manner, the area for coolant flow around the valve bridge can be increased and the sleeve 130 can be made relatively thinner in section than the walls 108 of housing 58, and so the critical valve bridge temperatures can be lowered which will in turn reduce the thermal stresses on the cylinder fire deck 38.
The invention also provides a coolant flow from the lower coolant jacket 92b which then flows through openings 146 into cavity 120 of each housing 58, around the clearance between the two piece sleeve 132a, 132b and the walls 108. The coolant then flows through openings 148 into upper coolant jacket 92a and thereafter out at each cylinder, between the intermediate and upper decks, into an external coolant manifold 168 of the engine 170 as shown in
The significance of this external coolant manifold 168 to the structural integrity of the cylinder head 10 is that it enables a cross-flow coolant path across the cylinder head 10, instead of the coolant flowing longitudinally along the cylinder head 10 which would result in higher pressure losses and reduced coolant velocities at the last cylinders to receive coolant. The cross-flow coolant path, enabled by the external coolant manifold 168, results in cooler metal sections and therefore reduced cylinder head deflections and lower stresses in the cylinder head material. The external coolant manifold 168 is usually located on the exhaust manifold side of the cylinder head 10, but may be located on the inlet manifold side of the cylinder head 10.
From the preceding descriptions, an invention is provided for a removable sleeve 130, fitted to a cylinder head 10, with the sleeve 130 being split horizontally into two mating sliding parts, the upper part 132a of the sleeve 130 being mechanically connected to the upper deck 72, and the lower part 132b being mechanically connected to the fire deck 38, with a joint between the two sleeve halves 132a and 132b to provide a gap between opposing contact surfaces 138, 140.
In one embodiment, removable sleeve 130 is used in a cylinder head 10 for at least one cylinder comprising two side walls 12, 14; two end walls 16, 18; three decks 38, 72 and 74 of preferred thickness; port walls 70, 78 of preferred thickness; a diamond shaped orientation of valve seats 20, 22, 24 and 26; a one haft upper coolant jacket 92a; a lower coolant jacket 92b and an external coolant manifold 168. In alternative embodiments, load bearing removable sleeve 130 may be replaced or used in conjunction with load bearing cylindrical housing 58 defining cavity 120 for fuel injector or ignitor 134. From this combination of features increased stiffness of the cylinder head has been shown through analysis, which may effectively inhibit undesirable stressing, deflecting and otherwise deforming of the cylinder head fire deck or other portions thereof, and a cylinder head geometry may be provided which is optimized for structural stiffness and peak operating cylinder pressure capability.
The one half coolant jacket is preferably located on the exhaust manifold side of the cylinder head. The fire deck 38 and upper decks 72 are each substantially thicker than the intermediate deck 74 and are each typically 150-300% times the thickness of the intermediate deck thickness.
The inventions disclosed herein are applicable to diesel, gasoline, liquefied propane gas (LPG), and compressed natural gas (CNG) fueled engines, which may have direct injection systems. In the case of the engine applications not utilizing compression ignition, the central injector may be substituted by an ignitor such as comprising a spark plug or micropilot injector. Also, while the invention has been described with respect to a cast cylinder head, which may be cast from metal such as iron or aluminum, it should be understood that the cylinder head may be manufactured in any suitable material or by any suitable process. More particularly, the process may provide a cylinder head having a monolithic structure. In other words, a mass of material formed as a single piece, unitary structure, which is without seams or joints associated with the connecting of two pieces or materials.
In order to improve, and preferably optimize, the structural stiffness and peak operating cylinder pressure capability of cylinder head 10, the following parameters were considered in a finite element analysis (FEA) for the design of cylinder head 10.
Output data from the finite element analysis included a computer generated estimate of the deflection of the fire deck directly beneath the fuel injector in response to certain load/stress criteria placed on the various computer models. The output data from the finite element analysis was then applied to an experimental design in which it was determined that the structural stiffness and peak operating cylinder pressure capability would be improved with the use of: a half upper water jacket; the greater thicknesses of the fire deck (17 mm), intermediate deck (10 mm), upper deck (17 mm) and port walls (10 mm); a cross-flow coolant jacket and a diamond port arrangement. Structural stiffness was considered to have improved if the deflection of the fire deck could be expected to decrease in light of the parameter being reviewed.
From the foregoing, the use of a half water jacket may be considered a most influential parameter in decreasing the deflection of the fire deck (and increasing the structural stiffness and peak operating cylinder pressure capability), followed by the increased thicknesses of the fire deck, intermediate deck, upper deck and port walls. The use of a cross-flow coolant jacket, as well as a diamond port arrangement may also be found to decrease the deflection of the fire deck.
While a preferred embodiment of the present invention has been described, it should be understood that various changes, adaptations and modifications can be made therein without departing from the spirit of the invention and the scope of the appended claims. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents. Furthermore, it should be understood that the appended claims do not necessarily comprise the broadest scope of the invention which the Applicant is entitled to claim, or the only manner(s) in which the invention may be claimed, or that all recited features are necessary.
