Patent Application
20170241368
The present disclosure generally relates to internal combustion engines and, more particularly, relates to ducted combustion systems for internal combustion engines.
Modern combustion engines may include one or more cylinders as part of the engine. The cylinder and an associated piston may define a combustion chamber. Fuel for combustion may be directly injected into the combustion chamber using various injection systems associated with the cylinders.
During engine operation, the injection systems may inject varying amounts of fuel/air mixture or fuel into the combustion chamber. Different mixtures and/or equivalence ratios of the fuel/air mixture within the fuel jet may produce different results during combustion. The manner in which the injected fuel mixes and/or interacts with the air and other environmental elements of the combustion chamber may impact combustion processes and associated emissions. Further, if the fuel and air mixing is inadequate, then suboptimal or incomplete combustion may take place which may create large amount of soot within the combustion chamber.
U.S. Patent Publication No. 2012/0186555 discloses ducted combustion within a combustion engine. The ducted combustion helps prevent/reduce soot formation within the combustion chamber. The '555 document discloses ducts which include fins disposed around a fuel jet injected by a fuel injector. Such ducts may form a passageway corresponding to an orifice of the fuel injector, into which fuel jets are injected. The fuel jets may be channeled into the ducts, which may improve fuel combustion as upstream regions of the fuel jet may be affected by faster and more uniform mixing as well as by an inhibition or reduction of entrainment of combustion products from downstream regions of the same or neighboring jets.
While the teachings of the '555 application are advantageous in providing an improved fuel/air mixture, further improvements in fuel/air mixtures are always desired, as such improvements may further reduce emissions and soot formation.
In an aspect of the present disclosure, a ducted combustion system for an internal combustion is disclosed. The ducted combustion system includes a combustion chamber, a fuel injector in fluid communication with the combustion chamber and configured to inject a sequence of at least two fuel charges into a combustion chamber during a combustion cycle and one or more ducts disposed within the combustion chamber and configured to receive at least a part of the fuel charges.
In another aspect of the present disclosure, an engine system is disclosed. The engine system includes a combustion chamber, a fuel injector in fluid communication with the combustion chamber and configured to inject a sequence of at least two fuel charges into a combustion chamber during a combustion cycle and one or more ducts disposed within the combustion chamber such that the at least two fuel charges at least partially enters the one of the one or more ducts.
In yet another aspect of the present disclosure, a method for operating an internal combustion engine is disclosed. The method includes injecting a sequence of at least two fuel charges into a combustion chamber during a combustion cycle. Further, the method includes directing at least a part of the fuel charges into one or more ducts disposed in the combustion chamber configured to provide a substantially uniform mixture of fuel and air within the combustion chamber.
Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
The present disclosure relates to a ducted combustion system for improving the combustion process and avoiding unwanted emissions into the atmosphere.
Referring to
As shown in
The intake valve 124 is configured to supply the air received from an air introducing system (not shown) into the combustion chamber 108. When the intake valve 124 is in an open position, the intake port 120 is in fluid communication with the combustion chamber 108 and air may be introduced into the combustion chamber 108. The opening of the intake valve 124 leads to the spring element 128 developing a restoring force to restore the intake valve 124 to its closed position. The restoring force of the spring element 128 brings the intake valve 124 to its closed position.
The exhaust valve 126 is configured to facilitate discharge of the combustion products from the combustion chamber 108. When the exhaust valve 126 is in an open position, the exhaust port 122 is in fluid communication with the combustion chamber 108 and exhaust/combusted gases may advance from the combustion chamber 108 and into the exhaust port 122. The opening of the exhaust valve 126 leads to the spring element 128 developing a restoring force to restore the exhaust valve 126 into its closed position. The restoring force of the spring element 128 brings the exhaust valve 126 to its closed position.
The ducted combustion system 118 further includes a fuel introducing system 116. The fuel introducing system 116 may be disposed on the cylinder head 102, as shown in
The ducted combustion system 118 further comprises a duct 136, as shown in
The ducts 136 are configured to interact with the fuel charge injected by the fuel injector 116 and alter the entrainment and combustion characteristics. In the embodiment illustrated in
The ducted combustion system 118 may further have an electronic control unit (ECU) 130 as shown in
In accordance with a given operating condition of the engine 100, the ECU 130 controls the injection timing of the plurality of fuel charges injected through the fuel injector 116. For e.g. based on the operating conditions of the engine 100, the ECU 130 may transmit at least two signals to the fuel injector 116 to provide two fuel charges within the combustion chamber 108 at two different instants of time. In an embodiment, the first fuel charge may be a pilot injection i.e. an injection event prior to completion of a compression stroke and before the main injection event. In an alternate embodiment, one of the at least two fuel charges may be a post injection i.e. an injection event after the completion of a main injection and during a power stroke. In various other embodiments, the fuel charges may be injected at different crank angles for e.g. in an embodiment there may be a plurality of fuel charges injected starting from 30 degrees before TDC (during compression stroke) to 40 degrees after completion of the compression stroke with 2 to 8 injection events.
In accordance with a given operating condition of the engine 100, the ECU 130 controls the amount of fuel injected through the plurality of fuel charges injected through the fuel injector 116 for e.g. in an embodiment a sequence of four fuel charges may be injected by the fuel injector 116. All the four fuel charges may inject the same amount of fuel into the combustion chamber 108. In an alternate embodiment, a sequence of three fuel charges may be injected into the combustion chamber 108. In this case different amount of fuel may be injected by each of the three fuel charges. For e.g. the first fuel charge may inject 20 percent fuel, the second fuel charge may inject 65 percent fuel and the third fuel charge may inject the remaining 15 percent fuel for the combustion cycle. It may be contemplated that any number of fuel charges may be injected by the fuel injector 116 wherein each of the fuel charge may deliver the same amount of fuel or a different amount of fuel into the combustion chamber 108.
The working of the engine 100 along with the ECU 130 will now be explained in detail with reference to
When the piston 106 reaches its bottom dead center the compression stroke is initiated. During the compression stroke both the intake valve 124 and exhaust valve 126 are in their closed position. Further, during the compression stroke, the piston 106 starts moving from the bottom dead center to the top dead center to compress the air within the combustion chamber 108 thereby preparing it for ignition. Simultaneously, the ECU 130 runs various algorithms stored in its memory on the data received from the sensors disposed on the intake valve 124 and the fuel introducing system 116 and predicts a multiple injection strategy to obtain maximum power during a specific operating condition of the engine 100. Close to the end of compression stroke, for e.g. in an embodiment the hot compressed air ignites with a very short delay after start of injection the injecting fuel through the fuel injector 116 into the combustion chamber 108. In the embodiment illustrated, when the air has been compressed by the piston 106, the ECU 130 transmits a signal to the fuel injector 116 based on the predicted injection strategy, to inject at least a sequence of two fuel charges, via the tip 132, into the combustion chamber 108 during the combustion cycle. The fuel injector 116 injects fuel charges as fuel jets through the one or more orifices 134 into the one or more ducts 136. The fuel jets interact with the duct walls 140. After interacting with the ducts walls 140 the fuel jets disperse within the combustion chamber 108 to create a uniform fuel/air mixture within the combustion chamber 108. The compressed charge may then be ignited by the heat generated by the high compression pressure generated in case the engine 100 is a diesel engines.
When the piston 106 reaches the top dead center after completing the compression stroke a power stroke is initiated. The power stroke marks the start of the second revolution of the combustion cycle. At this point the output shaft 112 has completed a full 360 degree revolution. During this stroke both the intake valve 124 and the exhaust valve 126 are in the closed position.
In an alternate embodiment, an ignition plug 110 may be disposed at least partially in the combustion chamber 108. The ignition plug 110 may be connected with the cylinder head 102 by a threaded connection or other methods known in the art. The ignition plug 110 may be a typical J-gap spark plug, a spark plug with a pre-chamber, rail plug, extended electrode, or laser plug or any other type of spark plug known in the art. The air/fuel mixture may be ignited using the ignition plug 110 in case the engine 100 is a spark ignited engine. Igniting the charge creates an explosion within the combustion chamber 108 and forcefully moves the piston 106 from the top dead center to the bottom dead center. This stroke produces mechanical work from the engine 100 to turn the output shaft 112.
Finally the exhaust stroke is initiated. During this stroke the piston 106 starts returning from the bottom dead center to the top dead center. The exhaust valve 126 is always in its open position during the exhaust stroke. The upward motion of the piston 106 along with the exhaust valve 126 in its open position, during the exhaust stroke, facilitates the products of combustion (combusted charge) to escape the combustion chamber 108.
Modern combustion engines may include one or more cylinders as part of the engine. The cylinder and an associated piston may define a combustion chamber. Fuel for combustion may be directly injected into the combustion chamber using various injection systems associated with the cylinders.
Direct injection systems may inject varying amounts of fuel/air mixture or fuel into the combustion chamber based on the operating conditions of the engine. Different mixtures and/or equivalence ratios of the fuel/air mixture within the fuel jet may produce different results during combustion. Improper mixing of air and fuel cause incomplete combustion. Thereby emitting large volumes of toxic gases and soot into the atmosphere.
In an aspect of the present disclosure, a ducted combustion system 118 for an engine 100 is disclosed. The ducted combustion system 118 comprises a combustion chamber 108, a fuel injector 116 and one or more ducts 136. The ducted combustion system 118 is configured to inject fuel into the combustion chamber 108 using the fuel injector 116. Further, the fuel jets injected by the fuel injector 116 are then passed through the one or more ducts to promote better mixing of air and fuel within the combustion chamber 108.
Within the combustion chamber 108, uniformity of the fuel/air mixture may be relevant to the combustion efficiency and may be relevant to the amount and type of combustion byproducts that are formed. For example, if the fuel/air mixture is too rich in fuel due to insufficient mixing within the fuel jets, then higher soot emissions may occur within the combustion chamber 108 and/or combustion efficiency may be affected. However, in the embodiment illustrated, using one or more ducts 136 disposed within the combustion chamber 108 may provide for more uniform fuel/air mixing within the fuel jets. By using one or more ducts 136, a lift-off length of a flame associated with a fuel jet may be altered (extended or reduced) to achieve an optimized lift-off length favoring low soot formation.
The ducted combustion system 118 provides for better mixing of fuel and air within the combustion chamber 108. Further, the ducted combustion system widens the fuel jet injected by the fuel injector 116 which enhances the entrainment characteristics and accordingly avoids incomplete combustion.
In another aspect of the present disclosure, a method 800 for operating an engine 100 is disclosed. The method 800 will be explained with reference to
The method in present disclosure of injecting a sequence of at least two fuel charges into a combustion chamber during a combustion cycle will enhance the impact of the duct on more uniform mixing by creating multiple leading and trailing edges, therefore may further reduce emissions and soot formation.
While aspects of the present disclosure have seen particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
