Engine having an air box baffle

An engine is disclosed. The engine may have an air box. The engine may further have an opening into the air box. The engine may additionally have a baffle positioned adjacent the opening. The engine may also have a cylinder defining an intake port, with the intake port positioned in the air box. The baffle may be configured to deflect air that passes through the opening to direct the air away from the intake port of the cylinder.

TECHNICAL FIELD

The present disclosure is directed to an engine and, more particularly, to an engine having an air box baffle.

BACKGROUND

Due to the rising cost of liquid fuel (e.g., diesel fuel), engine manufacturers have developed gaseous-fuel and dual-fuel engines that utilize low-cost gaseous fuel (e.g., natural gas). In these types of engines, gaseous fuel is introduced into the engine cylinders for subsequent combustion and production of mechanical power. In some engines (e.g., some dual-fuel locomotive engines), gaseous fuel is injected into each cylinder through air intake ports during an air intake portion of each engine cycle. The gaseous fuel mixes with the intake air to create a mixture that is combustible when ignited, such as via compression or ignition of a small amount of diesel fuel. These engines often include turbochargers that increase the power density of the engine by compressing and increasing the amount of air transferred to the engine and thus the amount of fuel that can be combusted during each engine cycle. The compressed air may be transferred into an air box associated with a cylinder bank and supplied through the air intake ports in the sides of each cylinder.

An example of a dual-fuel engine is described in U.S. Pat. No. 4,527,516, which issued to Foster on Jul. 9, 1985 (“the '516 patent”). The '516 patent discloses an engine that includes a supercharger that introduces intake air into an air chamber that surrounds each bank of cylinders. The intake air may be transferred from the air chamber to the engine cylinders through air intake ports. The engine of the '516 patent also includes a gas inlet pipe that introduces gaseous fuel into an engine cylinder through one of the air intake ports. The gaseous fuel mixes with the intake air for subsequent combustion to power the engine.

The engine of the '516 patent may suffer from problems associated with the introduction of supercharged intake air into the air chamber. For example, depending on the arrangement of the supercharger, the intake air flowing through the air chamber of the '516 patent may force gaseous fuel injected by the gas inlet pipe to exit a cylinder through the air intake ports and enter the air chamber. The escaped gas may subsequently enter a different cylinder, causing a uneven distribution of gaseous fuel in the engine cylinders.

This issue may be especially problematic with engines that include a turbocharger (or supercharger) that introduces compressed air into only one end of a cylinder bank. Due to its proximity, the cylinder that is closest to the turbocharger may experience higher variations of air flow rate across its air intake ports than the rest of the cylinders (e.g., higher flow rates at intake ports facing the turbocharger). The higher variation of air flow rate may cause injected gaseous fuel to escape and enter an air box that surrounds the cylinders. Therefore, in these applications, the cylinder closest to the turbocharger may be especially susceptible to experiencing a reduction in gaseous fuel concentration as compared to the rest of the cylinders in the cylinder bank.

The present disclosure is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to an engine. The engine may include an air box. The engine may further include an opening into the air box. The engine may additionally include a baffle positioned adjacent the opening. The engine may also include a cylinder defining an intake port, with the intake port positioned in the air box. The baffle may be configured to deflect air that passes through the opening to direct the air away from the intake port of the cylinder.

In another aspect, the present disclosure is directed to a method of operating an engine. The method may include supplying air through an opening into an air box of the engine. The method may also include deflecting at least some of the air that enters the opening away from a first intake port with a baffle positioned adjacent the opening. The method may further include delivering the deflected air into a second intake port.

DETAILED DESCRIPTION

FIG. 1illustrates an exemplary internal combustion engine10. Engine10is depicted and described as a two-stroke dual-fuel engine, although it should be understood that other types of engines are possible. Engine10may include an engine block12that at least partially defines a plurality of cylinders14. In an exemplary embodiment, the plurality of cylinders14may be arranged in a V-type configuration, including a pair of cylinder banks16and18. Each cylinder bank16and18may include eight cylinders14arranged in a straight-line configuration. While a V-type, sixteen-cylinder engine is described, it should be understood that engine10may include any number of cylinders14arranged in any configuration known in the art.

Each cylinder14may have an associated cylinder head20and a piston21slidably disposed within each cylinder14. For the purposes of this disclosure, it should be understood that each cylinder14may refer to a cylinder liner inside engine block12. Each cylinder14, cylinder head20, and piston21may together define a combustion chamber22that receives liquid fuel (e.g., diesel fuel) from a liquid fuel injector24and gaseous fuel from a gaseous fuel injector26(shown only inFIG. 2). Each cylinder14may also have an associated exhaust port27configured to be opened and closed to selectively allow exhaust to exit combustion chamber22. Each cylinder bank16,18may be associated with an air box32that surrounds at least a portion of each cylinder14in the respective cylinder bank16,18(i.e., at least a portion of each cylinder14is positioned in air box32). While air box32is described herein, it should be understood that, in other embodiments, air box32may be an intake manifold or other air supply passage configured to supply air or other gas to an engine cylinder.

Within each cylinder14, the associated piston21may be configured to reciprocate between a bottom-dead-center (BDC) or lower-most position, and a top-dead-center (TDC) or upper-most position. Each piston21may be operably connected to a crankshaft30in a manner known in the art. As crankshaft30rotates through about 180 degrees, each piston21may move through one full stroke between BDC and TDC. Engine10, being a two-stroke engine, may have a complete cycle that includes a power/exhaust/intake stroke (TDC to BDC) and an intake/compression stroke (BDC to TDC).

During a final phase of the power/exhaust/intake stroke, air may be drawn into each combustion chamber22via one or more air intake ports28defined by a sidewall of each cylinder14. In particular, as piston21moves downward within cylinder14, a position will eventually be reached at which air intake ports28are no longer blocked by a crown of piston21and instead are fluidly communicated with combustion chamber22. When air intake ports28are in fluid communication with combustion chamber22and a pressure of air at air intake ports28is greater than a pressure within combustion chamber22, air may pass from air box32through air intake ports28into combustion chamber22.

In addition, while air intake ports28are open, gaseous fuel (e.g., natural gas consisting of 90-95% methane) may be introduced into combustion chamber22by gaseous fuel injector26. The gaseous fuel may be injected through one or more air intake ports28via any number of gaseous fuel injectors26. Thereafter, the gaseous fuel may mix with the air to form a mixture of air and gaseous fuel within combustion chamber22. The mixture of air and gaseous fuel may be compressed and ignited by an injection of liquid fuel during the intake/compression stroke to produce mechanical power and restart the power/exhaust/intake stroke.

Each liquid fuel injector24may be positioned inside a respective cylinder head20and configured to inject liquid fuel into a top of combustion chamber22by releasing fuel axially towards an interior of cylinder14in a generally cone-shaped pattern. Liquid fuel injectors24may be configured to cyclically inject a fixed amount of liquid fuel, for example, depending on a current engine speed and/or load. In an exemplary embodiment, the liquid fuel may act as an ignition source for the gaseous fuel, such that a smaller amount may be necessary than what may be needed for engine10if it were running on only liquid fuel. While engine10is described herein as a dual-fuel engine, it should be understood that, in other embodiments, engine10may run only on gaseous fuel, which may be compression-ignited or spark-ignited, for example.

In an exemplary embodiment, engine10may include or be connected to a turbocharger46(shown only inFIG. 2) configured to introduce compressed air into air box32through openings48,50in engine block12. Turbocharger46may operate in a manner known in the art to increase the supply of air to each cylinder and thereby increase power output of engine10. For example, exhaust gas from engine10may cause rotation of a turbine to power a compressor that pressurizes air for introduction into air box32and eventually cylinders14. Further, it should be understood that turbocharger46is merely exemplary and that other air delivery devices (e.g., supercharger, inlet open to atmosphere, etc.) are possible.

A baffle60may be associated with air box32of each cylinder bank16,18. Each baffle60may be positioned adjacent a respective opening50. For example, baffle60may be attached to engine block12by an attachment section68at a location outside of air box32, and extend into air box32through opening50. In other embodiments, baffle60may be attached inside air box32. Baffle60may be configured to direct air from turbocharger46as it enters air box32through openings50.

FIG. 2illustrates a cross-sectional view of air box32, depicting some of cylinders14of cylinder bank16. Cylinders14of cylinder bank16may include a proximal cylinder34through a distal cylinder36, arranged in a straight line. For example, proximal cylinder34may be the eighth of eight cylinders (with distal cylinder36being the first). At least a portion of each cylinder14may be arranged in air box32. As described above, each cylinder14may include air intake ports28. Air intake ports28may be positioned inside air box32such that air may be transferred from air box32to combustion chambers22. While not shown, it should be understood that cylinder bank18may be arranged in a similar manner to cylinder bank16(e.g., a mirror-image arrangement within air box32).

Air box32may include a portion associated with cylinder bank16and a portion associated with cylinder bank18. Each portion may include a first wall38and a second wall40that separate air box32into a plurality of sections52,54, and56. In an exemplary embodiment, section56may be a singular section that connects each cylinder bank16,18of air box32to each other. Section56of air box32may be connected on two sides to a respective section54(only one shown), which may each be further connected to a respective section56. While air flow within the portion of air box32associated with cylinder bank16is described below, it should be understood that air flow within the portion of air box32associated with cylinder bank18may occur in a similar manner. Further, air flow through each portion of air box32may interact within section56.

First wall38and second wall40may extend in a direction substantially perpendicular to openings48,50. First wall38and second wall40may include a plurality of openings42,44, respectively, that fluidly communicate each of the plurality of sections52,54, and56. In an exemplary embodiment, openings42,44may be circular (as shown inFIG. 3). Some air from turbocharger46may enter a side section52of air box32through opening48. This air may enter a center section54of air box32through openings42to supply at least some of cylinders14. In addition, some air from turbocharger46may enter center section54directly through opening50. Further, some air that enters center section54may reach a side section56through openings44for further distribution and flow throughout air box32.

As depicted inFIG. 2, air that enters air box32through opening48may flow in a direction57parallel to first wall38. This air may fill side section52and distribute air to cylinders14through openings42. For example, the air that enters air box32through opening48may reach a distal end of side section52and be redirected into center section54by a pressure differential within air box32.

Unlike the air that enters opening48, at least some of the air that enters air box32through opening50may be prevented from flowing in a direction58parallel to first wall38. In particular, baffle60may be arranged to deflect air entering through opening50such that the air flows in a direction62that is angled with respect to first wall38. In this way, air may be prevented from flowing along direction58, straight into intake ports28of proximal cylinder34.

Baffle60may be generally arranged such that at least a distal portion extends from first wall38into center section54and towards proximal cylinder34at an angle θ with respect to first wall38. In this way, at least some air that is redirected by baffle60may flow in a direction parallel to the angle θ. In some embodiments, baffle60may be fixedly attached by attachment section68to engine block12, and extend away from first wall38at the angle θ. In an exemplary embodiment, the angle θ may be fixed at an angle of approximately 70-90°, and in particular, the angle θ may be approximately 81°.

In other embodiments, baffle60may be adjustable. For example, an extending portion of baffle60may be connected to attachment section68by a movable hinge that allows baffle60to move through a range of angles θ. Adjustable baffle60may be manually or electronically controlled to set the angle θ according to a particular criteria. For example, in some embodiments, a sensor70may measure a parameter and a controller72may send a signal to the movable hinge to set the angle θ, according to a particular algorithm, table, map, etc. The measured parameter may be any condition that indicates a flow and/or presence of air and/or gaseous fuel within air box32. For example, the measure parameter may be an air flow rate, a gaseous fuel flow rate, a ratio of air to gaseous fuel, a flow rate difference of air and/or gaseous fuel between two or more cylinders, an amount or presence of gaseous fuel in the air box, etc.

FIG. 3further illustrates an interior of air box32from the perspective of turbocharger46near cylinder bank16. Baffle60may extend into opening50, away from first wall38, and toward proximal cylinder34. Baffle60may include a plurality of sections, including intermediate sections64,65and a distal section66. As discussed above, distal section66may extend from first wall38at an angle θ.

Baffle60may be generally sized and positioned to deflect air that may otherwise directly enter air intake ports28of proximal cylinder34. In other words, baffle60may be positioned such that a height h1of distal section66overlaps a height h2of air intake ports28. In an exemplary embodiment, height h2may be approximately 15-25% of height h1. Therefore, air that enters opening50at the same level as air intake ports28may be deflected by baffle60away from at least one of intake ports28of proximal cylinder34. In order to accommodate a shape of opening50, a height h3of intermediate section64may be less than height h1. In this way, intermediate section64may traverse from outside of air box32into opening50, and distal section66may extend beyond a lower edge of opening50inside air box32to cover air intake ports28. For example, h3may be approximately 80-85% of h1. Intermediate section65may have the same height h1as distal section66.

FIGS. 4A-4Bfurther depict an exemplary embodiment of baffle60, which may correspond to baffle60located on the left side of engine10, as shown inFIG. 1. As shown inFIG. 4A, attachment section68may include a plurality of holes74, which may be used to attach baffle60to engine block12, such as by bolts. Attachment section68may be connected to intermediate section64via transition section76. In some embodiments, transition section76may be a rounded portion that fixedly connects intermediate section64to attachment section68. In embodiments in which baffle60is adjustable, transition section76may be a movable hinge, which may be electronically adjustable by controller72(shown only inFIG. 2). Intermediate section65and distal section66may be connected to intermediate section64such that distal section66extends at angle θ.

As shown in the top view depicted inFIG. 4B, the formation of angle θ may be gradual, with each intermediate section64,65and distal section66extending at different angles relative to first wall38and each other. As shown inFIG. 4B, intermediate sections64,65may extend away from first wall38(not shown inFIG. 4B, but which may be perpendicular to attachment section68) at angles of θ1and θ2, respectively. In an exemplary embodiment, a total angle formed by intermediate sections64,65(e.g., θ2) may be approximately 60-65% of the angle θ. For example, in the embodiment in which the angle θ is approximately 81°, intermediate section64may extend from first wall38at an angle of 30° (θ1=30°), intermediate section65may extend from intermediate section64at an angle of 20° (θ2=50°), and distal section66may extend from intermediate section65at an angle of 31° (θ=81°). However, it should be understood that these angle values are exemplary and that other angles are possible. Alternatively, one or more of intermediate sections64,65may be a rounded section. Any combination of sections that result in distal section66extending from first wall38at the angle θ is within the scope of baffle60.

The exemplary disclosed baffle60may be used in conjunction with turbocharger46to control the transfer of compressed air into air box32. An exemplary process by which engine10is operated and baffles60are used to help control the flow of air to cylinders14is described in more detail below.

Industrial Applicability

The exemplary disclosed baffle may be applicable to any engine that includes an air box or other air passage that supplies a gas (e.g., air) to one or more cylinders. The exemplary disclosed baffle may be particularly applicable to an engine that includes a turbocharger or supercharger, which may cause disproportionate air flow rates at the air intake ports of the engine cylinders. If the engine is a gaseous-fuel or dual-fuel engine, the exemplary disclosed baffle may be used to help prevent the entering intake air from forcing gaseous fuel out of some of the cylinders (e.g., the cylinder closest to the air entrance) and into other cylinders. This may help prevent a high variation of air flow rates across air intake ports, thereby helping to ensure that gaseous fuel remains in the appropriate cylinder. Reducing the variation of air flow rates and keeping gaseous fuel in the appropriate cylinders may help to maintain consistent ratios of air to gaseous fuel across cylinders and engine cycles, which may promote efficient operation of the engine. Operation of exemplary disclosed engine10and the effect of baffle60is described in more detail below.

During an exemplary engine cycle of engine10, each piston21associated with each cylinder14may move through a power/exhaust/intake stroke in which each piston21moves from the TDC position to the BDC position. At a certain point during the stroke, piston21may uncover air intake ports28, which become open to fluid communication with air box32. While air intake ports28are opened, a pressure difference may cause air to flow from air box32through air intake ports28into combustion chambers22.

Once piston21reaches the BDC position, it may reverse direction and begin an intake/compression stroke. During this stroke, air intake ports28may remain at least partially open until the crown of piston21reaches a point at which air intake ports28are covered and therefore closed off from air box32. Intake air may continue to enter combustion chamber22until air intake ports28are closed. In addition to receiving intake air, combustion chambers22may receive gaseous fuel from gaseous fuel injectors26. Gaseous fuel injectors26may inject gaseous fuel into combustion chamber22at any time while air intake ports28are opened, according to a particular injection timing of engine10.

After air intake ports28are closed, piston21may continue towards a TDC position, compressing the mixture of air and gaseous fuel. As the mixture of air and gaseous fuel within each combustion chamber22is compressed, a temperature of the mixture may increase. At a point when piston21is near TDC, a liquid fuel (e.g. diesel or other petroleum-based liquid fuel) may be injected into combustion chamber22via liquid fuel injector24. The liquid fuel may be ignited by the hot air/fuel mixture, causing combustion of both types of fuel and resulting in a release of chemical energy in the form of temperature and pressure spikes within combustion chamber22. During a first phase of a new power/exhaust/intake stroke, the pressure spike within combustion chamber22may force piston21downward, thereby imparting mechanical power to crankshaft30. At a particular point during this downward travel, exhaust ports27located within cylinder head20may open to allow pressurized exhaust within combustion chamber22to exit and the cycle will restart.

In an exemplary disclosed embodiment, the exhaust released through exhaust ports27may be used to power turbocharger46. Turbocharger46may operate to compress intake air and supply the air through openings48,50into air box32. For example, when air is removed from air box32via combustion chambers22, it may be replaced by air from turbocharger46. Air that enters through opening48may travel through side section52of air box32until it eventually reaches one of cylinders14via one of openings42. Additional air may enter air box32through opening50.

At least some of the air that enters opening50may be deflected by baffle60. In particular, air that enters opening50at the same level as a portion of air intake ports28may be deflected by baffle60away from proximal cylinder34. The redirected air may travel towards second wall40and around at least one of the intake ports28of proximal cylinder34. The air may subsequently enter another intake port28of proximal cylinder34or travel through at least one of center section54and side sections52,56before entering an intake port28of another cylinder14. Air entering through opening48may be delivered to the particular intake ports28that receive less air due to deflection by baffle60.

In an embodiment in which baffle60is adjustable, a control process may be utilized to set the angle θ of baffle60. While engine10operates, sensor70may monitor a condition, such as a flow rate of gaseous fuel out of proximal cylinder36. Sensor70may send a signal with the measured condition to controller72, which may determine if an adjustment to baffle60is necessary. If controller72determines that an adjustment is necessary (e.g., a measured flow rate of gaseous fuel is above a threshold), controller72may send a signal to a portion of baffle60(e.g., an electronically-controlled movable hinge) to adjust the angle θ of baffle60, accordingly, such as to reduce the flow rate of gaseous fuel out of proximal cylinder36.

Baffle60may be specifically configured for engine10to help prevent air from flowing directly into some of intake ports28of proximal cylinder34(e.g., intake ports28that face turbocharger46) and thereby causing a high variation of air flow rate across the air intake ports28of proximal cylinder34. In particular, the angle θ, height h1, and position of baffle60may be chosen such that a standard deviation of the air flow rate at each air intake port28of proximal cylinder34is commensurate with the other cylinders14. Further, baffle60may be adjustable such that the angle θ may be dynamically changed. In this way, baffle60may reduce a flow of gaseous fuel out of proximal cylinder34after it has been injected by gaseous fuel injector26, and a more even distribution of air and gaseous fuel between each cylinder14may be more consistently maintained. An even distribution of air and gaseous fuel may be advantageous because it may result in greater control over the ratio of air to gaseous fuel present in each cylinder14during each engine cycle, which is an important factor in maintaining efficient use of engine10. Therefore, baffle60may be used to help achieve more efficient operation of engine10.