Patent Publication Number: US-11655777-B2

Title: Parallel intake valve tumble flow engine

Description:
BACKGROUND 
     Over the years, efforts have been undertaken to increase efficiency and output from a variety of different types of internal combustion engines. In this regard, a variety of different factors are taken into account when designing the architectural layout for a given engine. That is, while certain components are generally consistent, such as the use of a piston, intake and exhaust valves, different firing mechanisms and others, the manner in which these components are arranged, oriented and work together may vary widely. Additional factors such as the type of fuel or overall output may also determine the type of engine design best suited for the application at hand. For example, an engine design that is well suited for use in a small motorcycle may be vastly different from the type that is well suited for use in large scale industrial equipment. Furthermore, efforts to decrease emissions to the extent possible plays an ongoing role in current engine designs. 
     For large scale industrial equipment, transportation vehicles and other high power output applications, diesel fuels are often utilized. In order to attain efficient output from diesel fuel and to handle structural loads of higher peak cylinder pressures, diesel engines generally utilize parallel valve stem architecture. Often, this means that the fuel-air mixture leading to the combustion chamber over the piston is delivered by way of multiple pathways running parallel to one another and likely the chamber itself as well. This may be advantageous for the combustion of diesel fuel because it may provide a relatively high compression ratio to support compression-ignited combustion. Indeed, fuels such as diesel are often referred to as compression combustion fuels. This pattern of vertical or parallel path fuel delivery into the combustion chamber tends to result in a swirling of the air flow. This is an added advantage for the generally slower burning, higher output diesel fuel. 
     In contrast to the diesel engine, a more conventional gas engine may be preferred where the specific torque requirements from the engine may be somewhat less. For example, a conventional gas engine may be a bit less expensive, less expensive to repair, and the fuel cost is generally more consistent and below that of diesel fuel. Thus, when it comes to transport, for example, it is generally more common to see conventional gas utilized in the everyday vehicle with diesel being reserved for larger trucks, busses or construction equipment. 
     Another difference when it comes to the conventional gas or spark-ignition engine is the intake valve architecture. That is, rather than arrange intake valves with a primary focus on compression ratios, it is preferable to employ an arrangement that facilitates tumble flow of fuel into the combustion chamber as opposed to a swirl flow. Higher rpm requirements also lead to larger valve sizes relative to bore diameter. This is often facilitated by a pent roof architecture of the cylinder block which angles the intake valves away from the noted parallel arrangement. Tumble flow is more well suited to generating turbulence and increasing the combustion rate of the spark-ignited fuel such as more conventional gasoline. 
     With the different intake designs and fuel types in mind, particularly in support of larger scale industrial applications, diesel fuel engines utilizing far square designs are generally employed. However, it has been proposed that emissions may be further minimized where more alternative fuel choices such as natural gas are utilized. Unfortunately, current equipment supporting large scale applications tend to employ diesel engines with the above-described parallel valve, swirling flow fuel delivery designs. This is a problem where a spark ignited fuel such as natural gas is sought to be utilized, given that the burn is more efficient and reliable where the flow is best introduced in a tumble type of manner similar to a conventional gas engine. 
     Presently, operators in possession of diesel engine equipment are not able to simply begin utilizing natural gas for sake of lowering emissions. As suggested, the available engines are not designed to effectively burn natural gas with a tumble flow intake (due to a pent roof design, for example). While a certain degree of retrofit is possible, it is not presently possible to attain a tumble flow from a swirl flow intake design where intake valves are arranged to facilitate diesel fuel combustion as described above. Rather, a complete cylinder head redesign would be required to accommodate a tumble of fuel flow into the combustion chamber. As a result, operators with capital already invested in available diesel engines are unlikely to begin utilizing a natural gas option simply for the sake of lowering emissions. This means that in the case of a traditional city bus, for example, vast amounts of particulate continue to be emitted into the habitable city space on an annual basis. Considering these emissions amplified across an entire bus fleet or even across the country in every major metro area for that matter, and the result of the inability to supply a practical natural gas retrofit for diesel engine applications, is quite significant. 
     SUMMARY 
     An engine is provided. The engine includes a multiple intake valve cylinder to accommodate a reciprocating piston with a combustion chamber there-above or there-adjacent. An intake valve assembly is provided with inlets to at least two intake valves of parallel arrangement for delivery of a spark-ignition fuel to the combustion chamber. At least one of these inlets facilitates an angled, substantially non-perpendicular tumble flow of the fuel to the chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a side cross-sectional schematic view of an embodiment of a parallel arranged multi-inlet valve assembly for a tumble flow, spark-ignition fuel engine. 
         FIG.  2    is a partially sectional perspective view of an embodiment of a vehicle employing the engine of  FIG.  1   . 
         FIG.  3    is a side cross-sectional schematic view of another embodiment of a parallel arranged multi-inlet valve assembly for a tumble flow, spark-ignition fuel engine. 
         FIG.  4    is a side perspective view of another alternate embodiment of a parallel arranged multi-inlet valve assembly for a tumble flow, spark-ignition fuel engine. 
         FIG.  5 A  is a top schematic view of a combustion chamber for a tumble flow, parallel arranged multi-inlet valve assembly of a far-square configuration. 
         FIG.  5 B  is a top schematic view of a combustion chamber for a tumble flow, parallel arranged multi-inlet valve assembly of a diamond configuration. 
         FIG.  6    is a flow-chart summarizing an embodiment of employing a spark-ignition fuel in a tumble-flow manner with a parallel arranged multi-inlet valve assembly engine. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it will be understood by those skilled in the art that the embodiments described may be practiced without these particular details. Further, numerous variations or modifications may be employed which remain contemplated by the embodiments as specifically described. 
     Embodiments detailed herein are directed at a unique architecture and design for attaining a tumble flow of fuel to an engine employing parallel valve stems. As used herein, the term “parallel” is meant to infer that fuel-air mixture directed at a combustion chamber through multiple inlets may be delivered from a valve assembly through one inlet that is arranged substantially parallel to another and in line with a central axis of the chamber. This parallel flow of fuel through multiple inlets is commonly displayed by diesel or other compression combustion engines. However, with the unique inlet valve architecture embodiments described herein, a tumble flow of the fuel may be attained such that engines employing these types architectures may be well suited for spark-ignited fuel use without requirement of a fundamental redesign of the cylinder head. Thus, “parallel” inlet engines, perhaps initially configured for non-spark-ignited fuel use such as diesel, may now be utilized with spark-ignited fuel where a unique corresponding parallel tumble flow assembly is made available. 
     As used herein, the term spark-ignited fuel includes fuels that are spark-ignited within a combustion chamber above a reciprocating piston head. These may include natural gas, gasoline, propane, fuels with a substantially methane composition and may further include alkanes and/or additional constituents such as carbon dioxide, nitrogen, hydrogen sulfide or helium. More conventional gasoline and propane would also be considered. These fuels might all be considered “spark-ignited” in contrast to compression ignition fuels such as diesel fuel. Regardless, for embodiments herein, so long as a tumble flow valve assembly is available to a parallel inlet engine for use with a spark-ignited fuel, appreciable benefit may be realized. 
     Referring now to  FIG.  1   , a side cross-sectional schematic view of an embodiment of an engine  100  is shown that accommodates a parallel multi-inlet valve assembly  101 . The term “assembly”  101  here is meant to reference the cylinder head channeling architecture that defines the fluid flow paths for the fuel-air mixture  115  to the valves  160 ,  170 . Further, as suggested above, the assembly  101  is “parallel” in that it is of an architecture where a common intake line  110  ultimately supplies an air-fuel mixture to first  160  and second  170  parallel intake valves. The valves  160 ,  170  themselves are parallel in that they that open and close in a manner that is parallel with a central axis of the combustion chamber  180  (as opposed to traveling in an angled manner as might be expected with a pent roof engine design, for example). 
     The parallel valve engine architecture illustrated is often found in assemblies which are commonly associated with diesel engines. However, for the present embodiments, the assembly  101  uniquely supports a tumble flow of air-fuel mixture intake as described below which facilitates spark ignited fuel use (e.g. as opposed to diesel or other compression combustion fuel). That is, even though the overall engine  100 , cylinder (defined by block  190 ) and other components remain of a parallel valve intake design, the flow of fuel into the chamber  180  is at least partially tumble in nature to facilitate spark ignition for fuels such as natural gas. 
     Continuing with reference to  FIG.  1   , the common intake line or valve  110  of the assembly  100  supplies an initial flow of mixture  115  that is delivered to a first valve  160  by way of an angled channel (θ). In the embodiment shown, the angle θ is about 30°. In other embodiments, the angle θ may be anywhere from about 20° to about 45° as measured against a perpendicular orientation such as the top of the block  190  defining the cylinder and combustion chamber  180 . Directing this initial flow  115  in an angular manner as described, then in combination with a secondary flow  155  sequentially through the secondary valve  170 , leads to a substantially tumbled flow of air-fuel mixture  115 ,  155  into the combustion chamber  180 . Thus, use of a spark ignited fuel such as natural gas may be supported. 
     The angular delivery may be tailored to also optimize velocity near the spark plug or to avoid structural elements of the cylinder head such as head bolt bosses. Further, the architecture of the assembly  101  may also be configured with other features of the engine  100  in mind such as a generally shallower combustion chamber  180  as is common with vertical stem engines initially configured for compression combustion. 
     Notice that the unique assembly  101  supports the tumble flow while allowing the parallel valves  160 ,  170 , stems  125 ,  127  and even the block  190  to remain of a conventional parallel arrangement (e.g. such as for a diesel engine). In the illustrated embodiment, even the secondary flow  155  is delivered in a vertical manner. However, in other embodiments, another angled delivery of this flow  155  may be supported (see  FIGS.  3  and  4   ). 
     It is of note that the assembly  101  is uniquely configured with angled and/or restrictive inlet channeling to the first valve  160  as described so as to deliver a tumble flow of mixture (e.g.  115 ,  155 ) to a block that might otherwise support swirl flow due to valve arrangement. That is, the unique architecture of the assembly  101  is such that tumble flow as described may be induced at an engine  100  otherwise configured for compression combustion, for example, of diesel fuel. However, this same, flat deck, vertical valve stem engine  100 , now retrofitted with a change out to a unique tumble inducing cylinder head assembly  101  as described may now make efficient use of spark ignited fuels such as natural gas. No other major engine redesign or replacement may be required. 
     Referring now to  FIG.  2   , a partially sectional perspective view of an embodiment of a vehicle  200  is illustrated that employs the engine  100  of  FIG.  1   . The vehicle  200  shown is a rig for pulling of cargo. However, any vehicle  200  traditionally powered by a diesel engine such as a city bus, construction equipment or to support other large scale industrial applications, may be envisioned employing the above described engine  100 . Once more, the engine  100  may remain substantially the very same traditional diesel engine but for change out of the cylinder head assembly  101  of  FIG.  1   , rendering the engine  100  non-diesel. 
     The result of the described changeout means that emissions from the engine  100  via the exhaust inlet  225  and pipe  250  are dramatically limited in terms of particulate. For example, consider a fleet of city busses being converted from traditional diesel to natural gas engines  100 , simply by the low cost conversion assembly  101  changeout illustrated in  FIG.  1   . In a major metropolitan area, this may effectively translate to a conversion from tons of potentially carcinogenic particulate emitted annually to no more than a negligible amount. Overall air quality and clarity might be improved by no more than the noted changeout on a fleet of busses, not to mention the numerous other diesel engine applications that may provide benefit from such a changeout. 
     Referring now to  FIG.  3   , is a side cross-sectional schematic view of another embodiment of a parallel multi-inlet valve assembly  301  is illustrated. In this embodiment, the arrangement is considered “far-square”. As with the embodiment of  FIG.  1   , the assembly  301  is configured for a tumble flow to support a spark-ignition fuel engine  100 . For this embodiment, the assembly  301  is “successive” in that it is of an architecture where a common intake valve  310  ultimately supplies air-fuel mixture to first  160  and second  170  intake valves successively (e.g. first to the first valve  160  and next to the second valve  170 ). However, the assembly  301  uniquely supports a tumble flow of air-fuel intake by way of the angled channel (θ). The assembly  301  remains roughly linear along the channel  310  including to the end portion  357  as illustrated. 
     Again, in the embodiment shown, the angle θ is about 30° but may be anywhere from about 20° to about 45°. Directing this flow  115  in an angular manner as described, provides a substantially tumbled flow of air-fuel mixture  115 ,  355  into the combustion chamber  180 . This remains the case even with the secondary flow  355  through the secondary valve  170  being somewhat less vertical. Thus, again, use of a spark ignited fuel such as natural gas may be supported, given that with or without restrictive enhancement, the majority of the tumble is facilitated by the angled channel  310  (or  110  in the case of the embodiment of  FIG.  1   ). 
     As indicated, the embodiments described above support a tumbled flow of the air-fuel mixture through the valves  160 ,  170 . As used herein, the term “tumble” is meant to infer any degree of tumble that is sufficient for supporting spark ignition with spark ignition fuels as noted. This may include a degree of cross-tumble behavior in the flow in the chamber  180 . Indeed, this is likely to occur to some extent given the offset nature of the valves  160 ,  170  for engines  100  that may have been initially designed with an architecture to support a swirl flow for a compression ignition engine. Nevertheless, the unique architecture of the assembly  101 ,  301  is such that tumble flow may be induced for an engine initially designed for swirl flow and compression ignition. 
     In another embodiment, the above-described tumble flow is further enhanced by the manner in which the successive supply of mixture is directed through to the second intake valve  170 . That is, in addition to the angled flow  115  through the first valve  160 , a restrictive flow is applied to the mixture through the second valve  170 . That is, in order to reach the end portion  357  of the line for direction to the second valve  170 , the mixture may first traverse a restriction of the assembly  101 . By way of comparison, the restriction that is presented here between the valves  160 ,  170  may be of a diameter (d) that is less than about half of the diameter (D) of the portion of the line of the assembly  101  that feeds the first valve  160 . 
     The restriction is such that the flow of air-fuel mixture  355  reaching and traversing the second valve  170  may be of higher velocity and less volume than the tumbling flow  115  through the first valve  160 . Additionally, this flow  355  proceeds in a manner that is more independent of the initial flow  115 . As a result, the flow of the mixture  155  into the chamber  180  through the second valve  170  is of a more vertical nature as guided by the cylinder wall defining the chamber  180  (as opposed to the more angular delivery illustrated in  FIG.  3   ). Thus, as this flow of air-fuel mixture  355  interacts with the angled flow  115  through the first valve  160 , the tumble of mixture into the chamber  180  is further enhanced. As a result, spark igniting of the fuel  115 ,  155  in the chamber  180  is also further enhanced. 
     Referring now to  FIG.  4   , a side perspective view of another alternate embodiment of a successive multi-inlet valve assembly  401  is illustrated. In this view, the vertical parallel stems over the valves  160 ,  170  are not illustrated but the engine  100  is the same flat head, parallel design as illustrated in  FIG.  1   . That is, apart from the assembly  401 , the same tumble flow, spark-ignition fuel, engine  100  is used. In this case the inlet valves  160 ,  170  are serviced with air-fuel mixture by separate dedicated intake lines or valves  405 ,  407 . This may be a “near square” configuration similar to  FIG.  1    with a fuel mixture reaching each valve  160 ,  170  at the same time. Although, far square designs may also be used as described above and with reference to  FIG.  5 A  below. Indeed, a diamond arrangement may also be employed (see  FIG.  5 B  described below). 
     Returning to the perspective view of  FIG.  4   , the midline angular orientation of the lines  405 ,  407  is less visibly apparent. However, with reference to the depicted angle (θ), again taken from a substantially horizontal point of reference, each line  405 ,  407  is roughly angled at about 30°, and may be anywhere from about 20° to about 45°. In one embodiment, the angle (θ) is substantially different between the individual lines  405 ,  407 . For example, one may be at 30° and the other at 35°. Indeed, different combinations of angles (θ), in combination with factors such as mixture flow velocity, volume, fuel type, etc., may be utilized to enhance tumble into the chamber as described herein. 
     The perspective view of the engine  100  also reveals the offset nature of the intake valves  160 ,  170  with respect to the portion of the block  490  over the cylinder. As with other successive, swirl design engines, the engine  100  includes exhaust valves  460 ,  470  adjacent the intake valves  160 ,  170 , even though the assembly  401  is configured to induce tumble in the chamber below as described above. 
     In one embodiment the intake valves  160 ,  170  are successive in terms of mixture intake to the chamber below with mixture through the first line  405  to the first valve  160  taking place in advance of mixture through the second line  407  to the second valve  170 . Further, with dedicated independent lines  405 ,  407  available, additional valving within the assembly  401  may be used to adjust or tailor timing of air-fuel mixture delivery as between each valve  160 ,  170 . Thus, tumbling of flow into the chamber below may be enhanced by such a tailored timing technique. 
     Referring now to  FIGS.  5 A and  5 B , top schematic views of a combustion chamber  180  defined by an engine block  190  are illustrated. The fuel delivery may or may not be successive as indicated. Regardless, a parallel multi-inlet valve assembly  101  is utilized to induce a tumble flow as indicated. In both cases, even though the assembly  101  is of a parallel valve arrangement, a tumble flow of mixture into the chamber  180  for sake of spark ignition is attained due to unique architecture of the assembly  101  as described herein. 
       FIG.  5 A  specifically, is a top schematic view of the combustion chamber  180  where the intake valves  160 ,  170  are successive and of a far-square configuration with the second valve  170  aligned substantially in direct front of the first valve  160  with respect to a midline between the intake  160 ,  170  and exhaust  460 ,  470  valves. The assembly  101  is of an architectural design as described above to support tumble flow into the chamber  180  through the intake valves  160 ,  170  while also shaped to suit the depicted far-square configuration. The same is true of an exhaust valve assembly  500  shape aligned with the exhaust valves  460 ,  470 . 
       FIG.  5 B  specifically, is a top schematic view of a combustion chamber  180  where the intake valves  160 ,  170  are successive and of a diamond configuration with the second valve  170  in front of and offset from the first valve  160  with respect to a midline between the intake  160 ,  170  and exhaust  460 ,  470  valves. The assembly  101  is again of an architectural design as described above to support tumble flow into the chamber  180  through the intake valves  160 ,  170  while also shaped to suit the depicted diamond configuration. Similarly, the same remains true of an exhaust valve assembly  501  shape that is aligned with the exhaust valves  460 ,  470 . 
     Referring now to  FIGS.  6   , a flow-chart summarizing an embodiment of employing a spark-ignition fuel in a tumble-flow manner with a parallel multi-inlet valve assembly engine is depicted. Specifically, as the spark-ignited fuel is directed to an engine as indicated at  610  it is separated to different intake valves (see  625 ). This may be achieved with the vertical valve stem engine being of a far square, near square or diamond configuration as indicated at  650 ,  630  and  670 . Nevertheless, due to unique embodiments of cylinder head assemblies detailed herein, a tumble flow of the air-fuel mixture may be generated in the combustion chamber of the engine sufficient for utilizing the spark-ignited fuel (see  690 ). 
     As a practical matter, embodiments described hereinabove include replaceable assemblies that may be used to convert a traditional diesel or other compression combustion engine to a spark-ignited engine. By way of specific example, this means that a diesel engine may be converted to a natural gas engine with little more than a cylinder head changeout. In addition to the tumble flow inducing features of such assemblies as described above, additional tumble enhancements may be employed. For example, the upper portion or “roof” defining the angled channel may include flat elongated regions or “planes”. In one embodiment the roof is split into three such planes. However, other configurations may be utilized to enhance tumble generation. 
     The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle and scope of these embodiments. Furthermore, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.