The technical field relates to internal combustion engines. More particularly, the field relates to improvements in designs for cylinder beads for internal combustion engines. The internal combustion engines may be engines that use liquid fuels such as diesel fuel or gasoline. Use of other types of suitable liquid fuels or gaseous fuels such as natural gas, or suitable combinations of any of the foregoing, is not precluded.
There is a continuing need for improvement in the fuel efficiency of internal combustion engines. An approach to improving fuel efficiency is decreasing the weight of components of an internal combustion engine used to power a vehicle. Conventional cylinder heads typically are designed in a manner that fails to achieve the goal of having a decreased weight, so as to allow for improvement in fuel efficiency of the engines, while also maintaining sufficient structural strength and sealing integrity.
There is also a continuing need for improvement in preventing intake charge air reheat (lower air temperature at IVC), and exhaust heat loss (greater exhaust thermal energy). Benefits of lower charge air temperature in intake air include: reducing the temperature at intake valve closing and improving volumetric efficiency; reducing NOx emission; and improving open cycle efficiency, if considered when sizing air handling. Benefits of increased energy in the exhaust gas include: improving open cycle efficiency and/or increase in air fuel ratio; flexibility in requirements to match of turbo, to be sized to accommodate increased energy; improving aftertreatment performance at low BMEP; and helping transient response through reduced time for engine warm-up.
Thermal barrier coatings, plastic intake sleeves, metal exhaust sleeves, ceramics, and dual-wall (air gap) technologies have all been used to reduce heat transfer in the cylinder head. Thermal barrier coatings alone do not provide a macro-level shift in heat transfer, the sleeves do not target the hottest part of the ports where the most heat transfer occurs, and ceramic can be difficult to use in fabrication of heads. Continued improvements are needed in cylinder head design.
In embodiments disclosed herein, the cylinder head comprises novel designs for undercuts, contours of the outer enclosure, coolant jackets, and other cavities within an outer enclosure, enabling the reduction of weight of the head while maintaining structural integrity of the head. The designs may employ a jumper tube to improve transfer of heat outside the outer enclosure. The designs help improve control of temperatures in intake side and exhaust side zones of the heads to improve operational efficiency of the engine. The embodiments of the cylinder head described herein reduce unwanted heat transfer from/to the intake, exhaust, and combustion flows in the engine to allow for greater system brake thermal efficiency.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention.
The above-mentioned and other features of this disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein:
While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.
The head includes for each combustion chamber an intake valve seat 104 in the nature of a bore for seating an intake valve 412 (see
As used in this disclosure, “boss” or “bosses” refers to structures that partially or fully surround the fastener bores into which fastener bolts are inserted. The terms “boss” or “bosses” are used herein regardless of whether the structure in question protrudes beyond a surface.
The head 100 has an exhaust side wall 112. The exhaust side wall 112 forms part of an outer enclosure of the body of the head 100, with the other main parts of the outer enclosure being formed by an upper wall 120, a bottom deck side wall 416 configured to be fastened to the engine block, and an intake side wall 202.
As seen in
In an embodiment, two fastener bosses, each one disposed between two adjacent combustion chambers in an engaged condition, may comprise boss cutouts formed on the bottom deck side of the two fastener bosses, such that a contact pressure balance of sealing forces is shared between fasteners inserted in the two bosses. The head 100 may comprise a beam formation 200 disposed between the two fastener bosses 110, 110 of the head 100, such that the beam 200 reinforces a head portion positioned between the two fastener bosses 110, 110 referenced in
Also shown in
Cavities and bores in cylinder heads may be formed by manufacturing methods employing cores or core packs, which are used as molds. The molds define the cavities and bores that are formed within the metal body of a head.
Also shown in
As exemplified in the embodiment shown in
In an embodiment, the head 100 comprises a beam formation disposed above the upper wall (face 502) of the cavity, and disposed between two fastener bosses 110, 110 of the head positioned between two adjacent combustion chamber bores, such that the beam reinforces a head portion that is positioned between the two fastener bosses. In
A method is provided for manufacturing a head 100 according to any of the embodiments described herein and depicted in one or more of the drawing figures. The method comprises forming a cylinder head using additive manufacturing to configure the head to minimize head weight. The inventors discovered improvements in configuration of cylinder heads using a lean integrative approach to develop the structure. These improved configurations allow the proper and efficient transfer of bolt compression loads to the most important sealing areas—the combustion seals and the external sealing surfaces. The configurations also improve desired transfer or conservation of energy in different zones of the head to improve efficiency of engine operation, reduce wear, reduce exhaust emissions, and improve combustion characteristics.
Among the improved configurations of the head 100 are the pyramidal-shaped cavity 500 being connected via an oil passage 510 to the first boss cutout 418, permitting fluid connection to allow for drain of oil between the central cavity 500 and the first boss cutout 418, as depicted in
In an example, the improved core configurations of embodiments herein may enable a six (6) kilogram weight reduction as compared to a baseline prior art head. Beneficial features of the described core pack are: a large center core (e.g., cavity 500) between cylinders which removes weight, enables oil to drain from the valve train to the engine block, and has large undercutting geometry; intake and exhaust undercut cores for the cap screws, which direct the clamping force of the cylinder head bolts to the combustion seal, a key loading location on the head. The cores also remove weight that does not serve any structural support.
Cyclical combustion forces repeatedly push the cylinder head away from the block. The inventors discovered configurations for effective management of structural members, along with the guidance of compressive bolt forces that are paramount to maintaining stiffness of the head and maintaining sealing integrity between the head and the block. The inventors employed topology optimization as a guiding framework to develop a lean structural framework of beams that connect the cylinder head bolt bores down the length of the head, across the head, and diagonally through the injector bore. Effective management of casting cores, through the use of undercutting geometry, allow the designer to guide the compressive bolt forces to critical sealing interfaces: 1. the combustion seal, and 2. the exterior sealing surface of the cylinder head (see
Among the improved configurations are the coolant jacket according to the present disclosure. The embodiments herein improve on prior designs by keeping “the hot side hot, and the cold side cold.” This lean jacket design maintains combustion face temperatures for iron life, improves hot and cold temperature transfers to the exhaust gas and intake charge air, respectively, and has the weight benefits of being approximately 5 L lower in coolant volume without loss of temperature maintenance efficacy. The hot side is kept hotter than in baseline prior configurations, which reduces heat transfer from exhaust gas, thereby improving turbo efficiency and heat available for aftertreatment/waste heat recovery. Cold side intake port temperatures are cooler than the baseline prior configurations, which reduces the heat transfer to the charge air, thereby improving volumetric efficiency of the engine.
Among the improved configurations is providing a coolant jacket wherein at least one of the intake valves has a wet seat (that is, coolant is provided in the vicinity of the valve seat). This cools the hottest parts of the intake ports (seat and valves) and helps keep the exhaust side temperatures in check. This wet seat intake valve configuration optionally may be combined with embodiments as shown wherein at least one of the exhaust valves also has a wet seat. The bottom of the poppet valves are the hottest parts of the combustion deck. Heat transfer from the poppet valves is threefold: to the intake gas; through the valve seats; and through the valve guides. The configuration of the present disclosure provides wet intake seats serving two purposes: the configuration enables better poppet valve head cooling, thus producing cooler head temperatures; and arrests the combustion heat flux from propagating through the iron (fire deck) to the intake ports, producing lower intake port temperatures overall. Wet exhaust seats prevent overheating the exhaust valve and seat.
Among the improved configurations is providing a coolant jacket having a coolant bridge between intake and exhaust ports (I-E bridge coolant passage). This feature arrests the exhaust temperature from propagating through the iron (I-E bridge) to the intake ports, producing lower intake port temperatures overall. Another improved feature is that this design of the jacket and wet seats enables positive coolant flow through each of the bridge wings.
Among the improved configurations is providing a coolant jacket having a “lean” jacket design as contrasted with prior art saturated jacket design. Embodiments described herein provide the benefits of positioning coolant in only the locations where it is absolutely needed, as contrasted with prior art heads that saturate open cavities with coolant flow. For intake charge air reheating, the benefits of the lean water jacket design of the disclosed embodiments are more prominent at higher coolant temperatures. Intake ports saturated and surrounded by more coolant than is necessary may increase the bulk charge air temperature. In the designs herein, coolant exits the head after cooling each cylinder independently (six locations in a six-cylinder engine), rather than in one location. This prevents having to run coolant to one exit location—where coolant has to move through more passages and be exposed to more cylinder head surface area, and accordingly, to more heat.
In embodiments of the invention, water jacket cores are configured for “parallel flow” across the cylinder head from side to side, to maximize the cylinder to cylinder temperature uniformity. This is contrasted with prior designs employing serial cooling down the length (in a direction along a longitudinal axis X) of the head. An additional benefit to the disclosed lean jacket is that it works even more efficiently with hotter coolant temperatures (+90 degrees C.), shown at 130 degrees C. in
Among the improved configurations are the positioning of the exhaust gas outlet in a recess 116 of the exhaust side wall 112 according to the present disclosure. The embodiments herein thus improve on prior designs by shortening the length of the exhaust gas port in the head (see
In embodiments of the invention, the exhaust ports end immediately after the valve guide, and a jumper tube is inserted which spans the distance between the head exhaust gas port and exhaust manifold port. This configuration also reduces the heating of intake charge. Intake charge temperature @ IVC expected to be comparable to ˜2K lower. The embodiments herein may be combined with construction of the head using improved formulations of ductile iron, and/or thermal barrier coatings to further reduce reheating of intake air. In an example application, the configurations of the exhaust port with jumper tube may maintain exhaust temperatures by +11K/cylinder. In an example configuration according to embodiments herein, the exhaust port area=11322 mm2 (in a 59% reduction from a prior art configuration @ 27806 mm2); Cylinder Head Mass=118 KG (5% reduction from a prior art configuration @ 124 KG); Coolant Volume=1 L (82% reduction from a prior art configuration @ 5.6 L); wet intake and exhaust seats were employed; equivalent combustion face temperatures to a prior art configuration were employed; and implemented a square valve pattern (as contrasted with a diamond valve pattern).
A configuration of the jumper tube herein may comprise a double seal construction that enables six degrees of freedom to compensate for part to part variation; assembly misalignment; and thermal growth.
In embodiments disclosed herein, the invention comprises a cylinder head of an internal combustion engine, the cylinder head being configured to cover a plurality of combustion chambers of the engine, and comprising at least one fastener boss configured for receiving insertion of a fastener that, in an engaged condition, fastens the cylinder head to a cylinder block of the engine, a bottom deck side of the cylinder head disposed near the cylinder block in the engaged condition, and a boss cutout formed in the fastener boss on the bottom deck side, wherein the boss cutout defines a portion of a wall of a sealed cavity that surrounds a shank portion of the fastener positioned in the boss cutout in the engaged condition. In one example of an embodiment, the sealed cavity contains air.
In embodiments disclosed herein, the invention comprises a cylinder head of an internal combustion engine configured to cover a plurality of combustion chambers of the engine, comprising a plurality of fastener bosses configured for receiving insertion of fasteners that, in an engaged condition, fasten the cylinder head to a cylinder block of the engine, and a bottom deck side of the cylinder head disposed near the cylinder block in the engaged condition, wherein at least two bosses disposed between two adjacent combustion chambers in an engaged condition comprise boss cutouts formed on the bottom deck side of the two bosses such that a contact pressure balance of sealing forces is shared between fasteners inserted in the two bosses.
In an example of an embodiment, in the cylinder head, at least one of the boss cutouts defines a portion of a wall of a sealed cavity that surrounds a shank portion of the fastener positioned in the boss cutout in the engaged condition.
In embodiments disclosed herein, the invention comprises a cylinder head of an internal combustion engine configured to cover at least two adjacent combustion chambers of the engine, each of the chambers having an intake valve and an exhaust valve positioned on its side near the adjacent chamber, comprising: an outer enclosure; a plurality of fastener bosses, each boss being configured for receiving insertion of a fastener that, in an engaged condition, fastens a bottom deck side of the cylinder head to a cylinder block of the engine; and a cavity formed within the outer enclosure, the cavity being formed generally in a shape of an inverted pyramid having a parallelogram-shaped upper face defining an upper wall of the cavity, and an apex pointing toward the bottom deck side of the cylinder head, wherein a central portion of the upper face of the pyramid is disposed at a position equidistant from centerpoints of each of the valves disposed between the two adjacent chambers. In an example of an embodiment, the pyramid comprises at least one rounded corner. In an example of an embodiment, the pyramid comprises at least one non-planar portion of a face of the pyramid.
In an example of an embodiment, the cylinder head comprises a beam formation disposed above the upper wall of the cavity, and disposed between two fastener bosses of the head positioned between two adjacent combustion chambers, such that the beam reinforces a head portion positioned between the two fastener bosses. In an example of an embodiment, the cylinder head further comprises a boss cutout formed in the fastener boss on the bottom deck side, wherein the boss cutout is fluidly connected to the cavity to permit passage of oil between the boss cutout and the cavity.
In an embodiments disclosed herein, the invention comprises a cylinder head of an internal combustion engine, comprising: an exhaust valve seat configured to engage an exhaust valve of a combustion chamber of the engine and an intake valve seat configured to engage an intake valve of the same combustion chamber; and a coolant jacket formed in the cylinder head, the coolant jacket comprising a coolant outlet disposed on an exhaust side of the cylinder head, a first coolant inlet disposed on an exhaust side of the cylinder head and a second coolant inlet disposed on an intake side of the cylinder head, an annular exhaust valve seat coolant passage extending along a circumference of the exhaust valve seat, and an annular intake valve seat coolant passage extending along a circumference of the intake valve seat, wherein the coolant outlet, the first and second coolant inlets, the exhaust valve seat coolant passage, and the intake valve seat coolant passage are fluidly coupled.
In an example of an embodiment, the cylinder head further comprises an intake-exhaust bridge coolant passage disposed proximate to an intake-exhaust bridge of the cylinder, and fluidly connected to the coolant outlet and the first and second coolant inlets. In an example of an embodiment, the coolant jacket further comprises an annular fuel injector coolant passage extending along a circumference of a seat or bore 102 that is formed in the head for receiving insertion of a fuel injector.
In embodiments disclosed herein, the invention comprises a cylinder head of an internal combustion engine configured to cover a plurality of combustion chambers of the engine, comprising: an outer enclosure and an exhaust gas outlet, wherein the outer enclosure comprises a depressed area in an exhaust side wall of the head, and the depressed area is positioned adjacent to the exhaust gas outlet such that the exhaust gas outlet is disposed adjacent to an exhaust valve guide formed in the cylinder head. In an example of an embodiment, an internal combustion engine comprises a cylinder head according to embodiments above, and further comprises a jumper tube fluidly coupled to the exhaust gas outlet and to an exhaust manifold of the engine.
In embodiments disclosed herein, the invention comprises a cylinder head according to any of the embodiments or examples above, in any combination of features recited herein. In embodiments disclosed herein, the invention comprises a method for forming a cylinder head according to any of the embodiments or examples above, in any combination of features recited herein, using additive manufacturing to configure the head.
One of skill in the art may appreciate from the foregoing that unexpected benefits are derived from application of the method, system, and apparatus to the problem of optimizing operation of an engine system, by reducing the weight of a cylinder head, by reducing the amount of metal required to form a cylinder head without reducing strength and stability, by improving temperature control in regions of a cylinder head, and/or by reducing the amount of coolant required to maintain favorable temperature conditions in a cylinder head. An unexpected benefit may be derived from application of the disclosed method, system, and apparatus without the need for including or adding additional components or parts, and/or without changing conventional features of the configuration of a conventional vehicle. Changes to configuration of a conventional engine system may add costs, weight, and complexity to manufacture, operation, and maintenance of the engine system. A key benefit contemplated by the inventors is improvement of cylinder head features and operations in a conventional engine system through use of the disclosed system, method, or apparatus, while excluding any additional components, steps, or change in structural features. In this exclusion, maximum cost containment may be effected. Accordingly, the substantial benefits of simplicity of manufacture, operation, and maintenance of standard or conventionally produced vehicles as to which the method and system may be applied may reside in an embodiment of the invention consisting of, or consisting essentially of, features of the method, system, or apparatus disclosed herein. Thus, embodiments of the invention contemplate the exclusion of steps, features, parts, and components beyond those set forth herein. The inventors contemplate, in some embodiments, the exclusion of certain steps, features, parts, and components that are set forth in this disclosure even when such are identified as being included, preferred, and/or preferable.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. For example, it is contemplated that features described in association with one embodiment are optionally employed in addition or as an alternative to features described in association with another embodiment. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
This application is a U.S. National Phase of International PCT Application No. PCT/US21/32737 filed on May 17, 2021, which claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 63/027,604 filed May 20, 2020, which are incorporated herein by reference in their entirety for all purposes.
This invention was made with Government support under DE-EE0007761 awarded by DOE. The Government has certain rights in this invention.
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PCT/US2021/032737 | 5/17/2021 | WO |
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WO2022/245329 | 11/24/2022 | WO | A |
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63027604 | May 2020 | US |