Advanced exhaust gas recirculation fuel supply control

Abstract

Exhaust gas recirculation control device comprising: a first donor cylinder (110) and a second donor cylinder (110) of a plurality of cylinders (120, 124) in an engine (102), wherein the first donor cylinder (110) and the second donor cylinder (110) are configured to provide an exhaust gas recirculation (EGR) flow to an air intake for the plurality of cylinders, and a controller configured to control a variable fuel throttle (154) in response to an engine operating condition, wherein the variable fuel throttle (154) provides a first amount of fuel (152) concurrently with an intake stroke (211) to the first donor cylinder (110) before providing the first amount of fuel (110) to at least one non-donor cylinder (110) in response to a change from fuel withholding to the plurality of cylinders (120, 124), wherein the first fuel quantity (152) is less than a fuel quantity (152) required by the transition, wherein the variable fuel throttle (154) subsequently provides a second amount of fuel (152) to a second donor cylinder (110), and wherein the second fuel quantity (152) is a fuel quantity (152) required by the transition.

Description

[0001] The present disclosure relates generally to fuel delivery control and, more particularly, to exhaust gas recirculation (EGR) fuel delivery control.

[0002] In particular, the present invention relates to an exhaust gas recirculation control device according to claim 1, a method for exhaust gas recirculation control according to claim 4 and a system for exhaust gas recirculation control according to claim 7.

[0003] EGR is used to reduce the amount of nitrogen oxides in exhaust gas produced by an internal combustion engine and can be used to reduce the occurrence of combustion knock. Generally, EGR systems recirculate a portion of the exhaust gas produced by a combustion event in an engine's combustion chamber back into the combustion chamber for a future combustion event. The recirculated exhaust gas lowers the temperature of the combustion components prior to combustion. The lower temperature of the combustion components promotes a reduction in the amount of nitrogen oxides produced as a result of the combustion process and can reduce engine knock. One or more dedicated donor cylinders can provide the exhaust gas to be recirculated.

[0004] US 2010 / 0 250 103 A1 discloses a method for controlling an internal combustion engine system. The internal combustion engine system includes an internal combustion engine, a valve drive mechanism that reciprocates an intake valve and an exhaust valve for a combustion chamber of the internal combustion engine, a turbocharger having a turbine and a compressor, and a first EGR passage connecting an exhaust passage downstream of the emission control device and an intake passage upstream of the compressor. The method includes shutting off fuel supply to the combustion chamber under a predetermined condition and reducing a lift of the intake or exhaust valve for the combustion chamber during the shutting off of fuel supply to the combustion chamber compared to a case where fuel is supplied to the combustion chamber.

[0005] US 2009 / 0 199 825 A1 discloses a device for efficiently operating an engine using exhaust gas recirculation (EGR). The device includes an exhaust manifold receiving exhaust gas from a first set of cylinders, an EGR manifold receiving exhaust gas from a second set of cylinders, and a passage with a variable restriction. The passage fluidly connects the exhaust manifold to the EGR manifold. The device further includes a controller with modules for interpreting engine operating conditions and controlling actuators in response to the engine operating conditions.

[0006] The subject matter of the present application has been developed in response to the current state of the art, and more particularly, in response to the problems and needs in the art that have not yet been fully addressed by currently available dedicated EGR fueling control techniques. Accordingly, in certain embodiments, the subject matter of the present application has been developed to provide an apparatus, method, and system for dedicated EGR fueling control.

[0007] Claim 1 discloses an apparatus for dedicated EGR fuel supply control. The apparatus includes at least one donor cylinder of a plurality of cylinders in an engine. The at least one donor cylinder supplies exhaust gas to an air intake for the plurality of cylinders. The apparatus further includes a variable fuel restriction that initially provides fuel concurrent with an intake stroke to the at least one donor cylinder in response to a change from withholding fuel to the plurality of cylinders to providing fuel to the plurality of cylinders.

[0008] Preferred modifications and features of the device are also the subject of dependent claims 2 and 3.

[0009] Claim 4 discloses a method for exhaust gas recirculation control according to the invention. Preferred modifications and features of the method are the subject of dependent method claims 5 and 6.

[0010] Finally, the invention also relates to a system for exhaust gas recirculation control, which is also covered by claim 7. Improvements and modifications of the system according to the invention are the subject of claims 8 and 9.

[0011] Throughout the description, reference to features, advantages, or similar language does not imply that all such features and advantages that can be realized with the subject matter of the present disclosure should be or are included in any single embodiment. Rather, language referring to features and advantages is intended to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Discussion of features and advantages and similar language may, but do not necessarily, refer to the same embodiment or implementation throughout the description.

[0012] The described features, structures, advantages, and / or characteristics of the subject matter of the present disclosure may be combined in any suitable manner in one or more embodiments and / or implementations. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the subject matter of the present disclosure. It will be apparent to one of ordinary skill in the art that the subject matter of the present disclosure may be practiced without one or more of the specific features, details, components, materials, and / or methods of a particular embodiment or implementation. In other instances, additional features and advantages may be apparent in certain embodiments and / or implementations that are not present in all embodiments or implementations of the invention.Furthermore, in some instances, well-known structures, materials, or processes are not shown or described in detail to avoid obscuring aspects of the subject matter of the present disclosure. The features and advantages of the subject matter of the present disclosure will become more apparent from the following description and the appended claims, or may be learned by practice of the invention as indicated below. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] To facilitate the understanding of the advantages of the subject invention, a more detailed description of the subject invention briefly described above is given with reference to specific embodiments illustrated in the attached drawings. Understanding that these drawings show only typical embodiments of the subject invention and are not to be considered limiting its scope, the subject invention is described and explained in additional detail through the use of the drawings, in which: Fig. 1 is a schematic diagram showing an EGR system; Fig. 2 a schematic diagram showing engine cylinders; Fig. 3 a diagram illustrating EGR fuel delivery and ignition; Fig. 4 a diagram illustrating EGR fuel delivery and ignition; Fig. 5 a diagram illustrating EGR fuel delivery and ignition; Fig. 6 a diagram illustrating EGR fuel delivery and ignition; Fig. 7 a diagram illustrating EGR fuel delivery and ignition; Fig. 8 a diagram illustrating EGR fuel delivery and ignition; Fig. 9 is a diagram illustrating EGR fuel delivery and ignition; Fig. 10A-D Side view representations of a piston; Fig. 11 a schematic block diagram of a control and Fig. 12 is a schematic flowchart of an EGR fuel supply control method. Detailed description

[0014] Throughout the specification, reference to "one embodiment" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Throughout the specification, references to "in one embodiment" and similar language may refer to the same embodiment, but not necessarily. Similarly, use of the term "implementation" means an implementation that includes a particular feature, structure, or characteristic described in connection with one or more embodiments of the present invention; however, in the absence of an explicit correlation indicating otherwise, an implementation may be associated with one or more embodiments.

[0015] Fig. Figure 1 is a schematic diagram illustrating one embodiment of an EGR system 100 that controls EGR fuel delivery in an internal combustion engine 102. The engine 102 may be a gasoline engine, a diesel engine, or the like.

[0016] System 100 includes various sensors for monitoring operating conditions within a given embodiment. Sensors may be strategically located within system 100 and may communicate with a controller 144. To illustrate the various locations and types of sensors that may be useful for determining a set of operating conditions for system 100, temperature sensors, pressure sensors, and mass flow sensors have been placed in the schematic diagram. One of ordinary skill in the art can determine the preferred placement and types of sensors for a particular application.

[0017] In the schematic representation of system 100, temperature sensors are denoted by the letter 'T', pressure sensors by the letter 'P', and mass flow sensors by the 'm-point' symbol. Furthermore, sensors may include virtual sensors that detect operating parameters of system 100 based on other information, such as engine revolutions per minute (RPM).

[0018] The system 100 includes an air intake 104 that receives a fresh air stream 106, which may flow through a compressor 108. The compressor 108 may increase the pressure on the air intake side of the engine 102 by compressing the fresh air stream 106 and may also allow more fuel to be burned in the cylinders 110.

[0019] The system 100 includes an exhaust manifold 116 that receives exhaust gas 118 from a non-donor cylinder set 120 of non-donor cylinders 110. In the illustrated embodiment of the system 100, the exhaust manifold 116 receives the exhaust gas 118 from the non-donor cylinders 110a, 110b, 110e, and 110d.

[0020] An EGR manifold 122 receives exhaust gas 118 from a donor cylinder set 124. In the illustrated embodiment, the EGR manifold 122 receives exhaust gas 118 from dedicated or donor cylinders 110e and 110f. In other embodiments of the system 100, the donor cylinder set 124 may include between one and three cylinders 110. For example, the donor cylinder set 124 may include one cylinder 110, cylinder 110f, with the remaining cylinders 110a, 110b, 110c, 110d, and 110e included in the non-donor cylinder set 120.

[0021] In one embodiment, the non-donor cylinder set 120 and the donor cylinder set 124 may each include any number of cylinders, such that each set 120, 124 includes at least one cylinder. For example, in a six-cylinder engine 102, the non-donor cylinder set 120 may include three cylinders 110, while the donor cylinder set 124 may include three cylinders 110. In another example, in a six-cylinder engine 102, the donor cylinder set 124 may include one cylinder 110, while the non-donor cylinder set 120 may include five cylinders 110. In another example (not shown), in a six-cylinder engine 102, the non-donor cylinder set 120 may include two cylinders, while the donor cylinder set 124 may include two cylinders 110, and two cylinders 110 of the engine 102 may exhaust separately from both the exhaust manifold 116 and the EGR manifold 122.

[0022] The donor cylinder set 124 may include any combination of cylinders 110, including non-sequential cylinders 110. For example, a donor cylinder set 124 may include three cylinders 110, such as cylinders 110d, 110e, and 110f. An eight-cylinder engine 102 may include a donor cylinder set 124 that includes between one and four cylinders 110. For any given internal combustion engine 102, the donor cylinder set 124 may include up to half of a total number of cylinders 110.

[0023] The system 100 further includes an EGR stream 112 that flows from the EGR manifold 122 to the air intake 104 and mixes with the fresh air stream 106 to form a mixed stream 114. In one embodiment, the system 100 further includes an EGR cooler 132 that cools the EGR stream 112.

[0024] The exhaust passage 136 may direct exhaust gas 118 from the exhaust manifold 116 through a turbocharger 138. In one embodiment, the turbocharger 138 is a variable geometry turbocharger (VGT) 138 that induces variable backpressure at the exhaust manifold 116. The system 100 further includes an aftertreatment system 142 downstream of the turbocharger 138.

[0025] The system 100 includes a variable fuel restriction 154 that provides fuel from a fuel source 150. The variable fuel restriction 154 may be a valve, a metering device, or the like. The fuel source 150 may be a carburetor, a fuel injector, or the like. The variable fuel restriction 154 may be configured in the carburetor. Alternatively, one or more variable fuel restrictions 154 may be configured in the fuel injector. The variable fuel restriction 154 controls the provision of the fuel 152 to the air intake 104. The variable fuel restriction 154 may be controlled by the controller 144.

[0026] In one embodiment, each cylinder 110 has a dedicated variable fuel restriction 154 (not shown). Alternatively, the donor cylinder set 124 has a dedicated first variable fuel restriction 154, while the non-donor cylinder set 120 has a dedicated second variable fuel restriction 154 (not shown).

[0027] Again on Fig. Referring to Figure 1, system 100 includes a controller 144 configured to interpret sensor information for a set of engine operating conditions for system 100. Controller 144 may communicate an actuator signal to at least one actuator in system 100 in response to the set of engine operating conditions. Variable fuel throttle 154 may comprise an actuator in system 100. VGT 138 may also be an actuator in system 100.

[0028] The system 100 includes a device 134 for controlling EGR fuel delivery. In one embodiment, the device 134 includes the EGR manifold 122, the donor cylinder set 124, the variable fuel restriction 154, and the fuel source 150. The device 134 may also include the controller 144.

[0029] During operation of the system 100, the variable fuel restriction 154 may withhold fuel 152 from the air intake 104. For example, the variable fuel restriction 154 may withhold fuel 152 from the air intake 104 while the engine 102 is idling or under a light load. However, when the system 100 transitions from idling to providing power, the variable fuel restriction 154 again provides fuel 152 to the air intake 104. Unfortunately, because the donor cylinders 110 have not combusted any fuel 152, there is little or no EGR flow 112 available to provide to the air intake 104. As a result, combustion in the cylinders 110 may be susceptible to engine knock and / or the generation of nitrogen oxides.

[0030] The embodiments described herein control the provision of fuel 152 to cylinders 110 such that the donor cylinders 110 of donor cylinder set 124 receive the fuel 152 first, combust the fuel 152, and provide the EGR flow 112 to the other cylinders 110 of engine 102, as described below. As a result, the number of cylinders that fire before the EGR flow 112 is available to the air intake 104 is reduced.

[0031] On Fig. 2, the cylinders 110 for the engine 102 are Fig. 1. The engine 102 is shown having six cylinders 110. However, embodiments may be practiced with any number of cylinders 110. The cylinders 110 may fire in a specific firing order. For a six-cylinder engine 102, the firing orders may include, but are not limited to, 1-5-3-6-2-4, 1-4-3-6-2-5, 1-6-5-4-3-2, 1-2-3-4-5-6, 1-4-2-5-3-6, 1-4-5-2-3-6, 1-6-3-2-5-4, 1-6-2-4-3-5, and 1-6-2-5-3-4.

[0032] For a four-cylinder engine 102, the firing orders may include, but are not limited to, 1-3-4-2, 1-2-4-3, 1-3-2-4, 1-4-3-2, and 1-2-3-4. For a three-cylinder engine 102, the firing orders may include 1-2-3 and 1-3-2.

[0033] For an eight-cylinder engine 102, the firing orders may include, but are not limited to, 1-8-4-3-6-5-7-2, 1-8-7-2-6-5-4-3, 1-3-7-2-6-5-4-8, 1-5-4-8-7-2-6-3, 1-6-2-5-8-3-7-4, 1-8-7-3-6-5-4-2, 1-5-4-2-6-3-7-8, 1-5-6-3-4-2-7-8, 1-5-3-7-4-8-2-6, 1-2-7-8-4-5-6-3, 1-2-7-3-4-5-6-8.

[0034] For simplicity, the six-cylinder firing order 1-5-3-6-2-4 is described herein. However, the embodiments may be implemented for any firing order for any number of cylinders 110.

[0035] On Fig. Referring to Figure 3, a graph 221 illustrates prior art EGR fueling and ignition. Fuel delivery 210 from fuel source 150 through variable fuel restriction 154 is shown on the vertical axis. Fuel quantity 216 increases in the upward direction.

[0036] The cylinders 110 with an intake stroke 211 are shown along the horizontal axis. Earlier intake strokes 211 over time are shown on the left and later intake strokes 211 over time are shown on the right. The cylinders 110 are shown receiving fuel 152 in the firing order 1-5-3-6-2-4. In addition, firing 212 of each cylinder 110 for the subsequent power stroke is shown after the intake stroke 211 is shown, and a compression stroke is shown with the intake stroke 211. For ease of illustration, subsequent firing 212 during the power stroke is shown with the intake stroke 211, indicating that firing occurs for the power stroke associated with the intake stroke 211, although one skilled in the art will recognize that firing 212 does not occur concurrently with the intake stroke 211, but rather occurs after the intake stroke 211.

[0037] In the illustrated embodiment, the variable fuel throttle 154 transitions from withholding fuel 152 from the air intake 104 to providing fuel 152 to the air intake 104. The transition may occur in response to a transition event 218, such as acceleration of the engine 102. For example, the engine 102 may be idling while descending a hill. While idling, the variable fuel throttle 154 may withhold fuel 152 from the air intake 104. When the bottom of the hill is reached and the engine 102 is requested to provide power, the variable fuel throttle 154 transitions from withholding fuel 152 to providing fuel 152. Accelerating the engine 102 to provide power is an example of a transition event 118.

[0038] In the illustrated embodiment, cylinder 2 110b first receives the supply of fuel 152 and subsequently ignites 212 in response to the switch event 218. Unfortunately, since the donor cylinder set 124 did not fire prior to the provision of fuel 152 to cylinder 2 110b, no EGR flow 112 is available in the air intake 104. Likewise, when cylinder 4 110b and cylinder 1 110a fire 212, no EGR flow 112 is still available in the air intake 104 because the cylinders 110 of the donor cylinder set 124 have not yet fired. As a result, cylinder 2 110b, cylinder 4 110d, and cylinder 1 110a may generate nitrogen oxides and are susceptible to engine knock.

[0039] On Fig. 4, a diagram 222 shows an embodiment of EGR fuel delivery and ignition. The organization of the diagram 222 corresponds to the organization of the diagram 221 of Fig. 3. In one embodiment, fuel supply 210 indicates the fuel 152 provided to the air intake 104. Alternatively, fuel supply 210 indicates the fuel 152 provided to an individual cylinder 110. Controller 144 may control the provision of fuel 152 and the firing 212 of each cylinder 110. Each cylinder 110 may be fired 212 by spark ignition.

[0040] As in Fig. 3, the switchover event 218 is depicted occurring during the intake stroke 211 of cylinder 6 110f. However, instead of immediately providing fuel 152 to the air intake 104 after the switchover event 118, the variable fuel restriction 154 provides fuel 152 concurrently with the intake stroke to cylinder 5 110e, a donor cylinder 110 of the donor cylinder set 124. Furthermore, the variable fuel restriction 154 may withhold fuel 152 from the air intake 104 while the non-donor cylinders 110, such as cylinder 2 110b, cylinder 4 110d, and cylinder 1 110a, have intake strokes 211.

[0041] As a result of providing fuel to the donor cylinder, donor cylinder 5 110e, the EGR flow 112 in the air intake 104 begins to be available for subsequent intake strokes 211. Therefore, the number of cylinders 110 supplied with fuel 152 before the EGR flow 112 is available in the air intake 104 is reduced.

[0042] On Fig. 5, a diagram 223 shows an embodiment of EGR fuel delivery and ignition. The organization of diagram 223 corresponds to the organization of diagrams 221 and 222 of Fig. 3 and Fig. 4. As shown in Figure 222, in response to the switching event 218, the variable fuel throttle 154 withholds fuel 152 from cylinders 110 until the intake stroke 211 for one of the donor cylinders 110, cylinder 5 110e. Then, the variable fuel throttle 154 provides fuel 152 to cylinder 5 110e for the intake stroke of cylinder 5 110e. The donor cylinder 110, cylinder 5 110e, subsequently fires 212, creating the EGR flow 112 for the air intake 104.

[0043] However, providing fuel 152 to cylinder 5 110e and firing it 212 does not immediately generate the EGR flow 112 for the intake stroke 211 of the subsequent cylinder, in the illustrated example a non-donor cylinder 110, cylinder 3 110c. Therefore, the controller 144 may not fire 212 the subsequent non-donor cylinder 110. Instead, the controller 144 may fire 212 a subsequent donor cylinder 110, in the illustrated example cylinder 6 110f, to continue generating the EGR flow 112. The variable fuel throttle 154 may provide the fuel 152 to a non-donor cylinder 110, in the example shown, cylinder 2 110b, when the EGR flow 112 is available from a donor cylinder 100, such as cylinder 5 110e.

[0044] On Fig. 6, a diagram 224 shows an embodiment of EGR fuel delivery and ignition. The organization of the diagram 224 corresponds to the organization of the diagrams 221-223 of the Fig. 3- Fig. 5. Fuel 152 is provided to a first donor cylinder 110, cylinder 5 110e, and it ignites 212 in response to the switch event 218. However, the resulting EGR flow 112 may be insufficient. As a result, the variable fuel throttle 154 does not provide fuel 152 for the intake stroke 211 to a subsequent non-donor cylinder 110, cylinder 3 110c, as shown in Fig. 6. In addition, the controller 144 may not fire 212 the subsequent non-donor cylinder 110, cylinder 3 110c.

[0045] The variable fuel throttle 154 may then provide fuel 152 to the subsequent donor cylinder 110, cylinder 6 110f, and then the subsequent donor cylinder 110 is fired 212. Thus, fuel 152 is provided to two donor cylinders 110 before fuel 152 is provided to a non-donor cylinder 110.

[0046] In one embodiment, variable fuel throttle 154 provides fuel 152 only to a non-donor cylinder 110 when sufficient EGR flow 112 is available to air intake 104. Controller 144 may employ one or more pressure sensors, temperature sensors, or the like to determine whether sufficient EGR flow 112 is available, as described below. Alternatively, controller 144 may predict sufficient EGR flow 112 as a function of combusted fuel 152, as described below.

[0047] Controller 144 may begin providing fuel 152 to cylinders 110 of non-donor cylinder set 120 when sufficient EGR flow 112 is present. In the example shown, a first non-donor cylinder 110 of non-donor cylinder set 120, cylinder 2 110b, is fired 212 after fuel 212 is provided to cylinders 110 from donor cylinder set 124.

[0048] On Fig. 7, a diagram 225 illustrates an embodiment of EGR fueling and ignition. The organization of the diagram 225 corresponds to the organization of the diagrams 221-224 of the Fig. 3- Fig. 6. However, four complete combustion cycles are shown.

[0049] A first donor cylinder 110, cylinder 5 110e, is supplied with fuel 152 and ignited 212 in response to the switch event 218. If the EGR flow 112 is insufficient, the variable fuel throttle 154 may withhold fuel 152 from the subsequent intake stroke 211 for a non-donor cylinder 110 in the firing order, cylinder 3 110c, and the subsequent non-donor cylinder 110 is not fired 212. The variable fuel throttle 154 may provide fuel 152 to the subsequent donor cylinder 110, cylinder 6 110f, and the subsequent donor cylinder 110 is fired 212. If the EGR flow 112 is still insufficient, the variable fuel throttle 154 may withhold fuel 152 from subsequent intake strokes 211 for other non-donor cylinders 110 until fuel 152 is made available for the subsequent donor cylinder 110, cylinder 5 110e.In one embodiment, the variable fuel throttle 154 only provides fuel 152 to each donor cylinder 110 and withholds fuel 152 from each non-donor cylinder 110, and the controller 144 only fires 212 each donor cylinder until sufficient EGR flow 112 is present.

[0050] On Fig. 8, a diagram 226 illustrates one embodiment of EGR fueling and ignition. The organization of the diagram 226 corresponds to the organization of the diagrams 221-225 of the Fig. 3- Fig. 7. Figure 226 shows EGR fuel delivery with modulated torque.

[0051] In one embodiment, the variable fuel throttle 154 withholds fuel 152 from the non-donor cylinder 110 following the switch event 218 until the intake stroke 211 of a first donor cylinder 110 when the variable fuel throttle 154 provides fuel 152. The subsequent non-donor cylinder 110 may not be fired 212 due to insufficient EGR flow 112. The non-fire of the subsequent non-donor cylinder 110 may be noticeable and / or negatively perceived by an operator.

[0052] To make the non-firing of non-donor cylinders 110 less noticeable, embodiments may reduce the torque generated by the donor cylinders 110 while the non-donor cylinders 110 are not being fired 212. In the illustrated embodiment, the amount of fuel 216 is less than would otherwise be required by the switchover event 218. As a result, the firing of the donor cylinders 110 followed by the non-firing of one or more non-donor cylinders 110 is less noticeable. In an alternative embodiment, the torque of the donor cylinders 110 may be reduced by delaying the center of heat release for the donor cylinders 110, as described below. Delaying the center of heat reduces torque without reducing the generated exhaust 118.

[0053] On Fig. 9 Referring to Figure 9, a diagram 227 shows an embodiment of EGR fuel delivery and ignition. The organization of the diagram 227 corresponds to the organization of the diagrams 221-226 of the Fig. 3- Fig. 8. Figure 227 shows an alternative embodiment of EGR fuel delivery with modulated torque.

[0054] In one embodiment, the variable fuel throttle 154 withholds fuel 152 from non-donor cylinders 110 following the switch event 218 until the intake stroke 211 of a donor cylinder 110 when the variable fuel throttle 154 provides fuel 152. The variable fuel throttle 154 may withhold fuel 152 from the subsequent non-donor cylinders 110, and the subsequent non-donor cylinders 110 may not be fired 212 due to insufficient EGR flow 112. However, the non-fire of the subsequent non-donor cylinder 110 may be noticeable and / or perceived as negative by an operator, such as for Fig. 8 described.

[0055] To make the non-firing of the non-donor cylinders 110 less noticeable, embodiments may reduce the torque generated by the donor cylinders 110 while fuel 152 is withheld from the non-donor cylinders 110 and / or while the non-donor cylinders 110 are not ignited 212. In the illustrated embodiment, the amount of fuel 216 is less than would otherwise be required by the switch event 218. As a result, the initial provision of fuel 152 concurrent with the intake stroke 211 of the donor cylinder 110 is followed by the non-firing of one or more non-donor cylinders 110, which is less noticeable. In an alternative embodiment, the torque of the donor cylinders 110 may be reduced by delaying the center of heat release for the donor cylinders 110, as described below.

[0056] Fig. 10A-D are schematic side view drawings of a piston 148 in a cylinder 110. Fig. 10A and Fig. 10B show the intake stroke with piston 148 moving downward and drawing the fresh air flow 106, the EGR flow 112, and the fuel 152 into the cylinders 110. Fig. Figure 10C shows a compression stroke with cylinder 148 where the fresh air flow 106, the EGR flow 112, and the fuel 152 are compressed. Fig. 10D shows the firing 212 of cylinder 110 to initiate the power stroke. Cylinder 110 may be fired 212 by a spark ignition device 230, such as a spark plug, to generate optimal torque. However, controller 144 may delay firing 212 to delay the center of heat release to reduce the torque generated by cylinder 110.

[0057] On Fig. 11, the controller 144 is Fig. 1. The controller 144 may include a processor 305, a memory 310, and communication hardware 315. The memory 310 may be a semiconductor memory, a micromechanical memory, or the like. The memory 310 may store program code. The processor 305 may execute the program code to perform the functions of the system 100 and the device 134. The communication hardware 315 may communicate with other devices. For example, the communication hardware 315 may communicate with the variable fuel throttle 154, the spark ignition device 230 firing the cylinders 110, and the like. Alternatively, the controller 144 may be comprised of dedicated semiconductor logic.

[0058] On Fig.Referring to Figure 12, an EGR fueling control method 500 is shown. Method 500 may be performed by elements of system 100 and / or device 134. In one embodiment, controller 144 controls the functions of method 500.

[0059] Method 500 begins, and in one embodiment, controller 144 identifies 502 a transition event 218. Transition event 218 may be a transition from no fueling to cylinders 110 to fueling to cylinders 110. Transition event 218 may be an acceleration of engine 102 from idle operation of engine 102. In one embodiment, variable fuel restriction 154 withholds fuel 152 from air intake 104 and cylinders 110 prior to transition event 218.

[0060] Controller 144 may determine 504 whether a subsequent intake stroke 211 is for a donor cylinder 110. The subsequent intake stroke 211 may be the intake stroke that starts after a provision time interval. The provision time interval may be a time required to provide fuel from variable fuel restriction 154 for an intake stroke 211.

[0061] If the subsequent intake stroke 211 is not intended for a donor cylinder 110, the controller 144 may allow the firing order of the cylinders 110 to advance to the intake stroke 211 for a subsequent cylinder 110. In one embodiment, the controller 144 allows the firing order to advance to the subsequent cylinder 110 without the variable fuel throttle 154 providing fuel 152 to the cylinders 110.

[0062] If the controller 144 determines 504 that the subsequent intake stroke 211 is for a donor cylinder 110, the variable fuel throttle 154 provides 506 fuel 152 to the donor cylinder 110. Furthermore, the donor cylinder 110 is subsequently ignited 212 during a power stroke with combustion of the fuel 152. In one embodiment, the torque of the donor cylinder 110 is reduced.

[0063] In response to providing fuel 152 to the donor cylinder 110 and igniting it 212, the controller 144 may determine 510 whether sufficient EGR flow 112 is available. In one embodiment, the controller 144 uses one or more of pressure sensors, temperature sensors, and / or mass flow sensors to determine 510 whether sufficient EGR flow 112 is present. The controller 144 may determine 510 that sufficient EGR flow 112 is present when the EGR flow exceeds an EGR threshold.

[0064] For example, controller 114 may receive a mass flow value of EGR flow 112 from a mass flow sensor and determine 510 that sufficient EGR flow 112 is present when the EGR mass flow exceeds an EGR mass flow threshold. Alternatively, controller 114 may receive a pressure value of EGR flow 112 from a pressure sensor and determine 510 that sufficient EGR flow 112 is present when the EGR flow pressure exceeds an EGR pressure threshold. In a particular embodiment, controller 114 receives a temperature value of EGR flow 112 from a temperature sensor and determine 510 that sufficient EGR flow 112 is available when the EGR flow temperature exceeds an EGR temperature threshold.

[0065] Alternatively, controller 144 may calculate an exhaust gas estimate as a function of combusted fuel 152. In a particular embodiment, controller 144 calculates the exhaust gas estimate as a function of combusted fuel 152 and / or pressure and / or temperature and / or mass flow. Controller 144 may use a lookup table to perform the calculation.

[0066] In one embodiment, the controller 144 determines 510 that sufficient EGR flow 112 is available when a certain number of donor cylinders 110 have been supplied with fuel 152 and fired 212. The certain number of donor cylinders 110 may range from 1 to 4 donor cylinders 110.

[0067] If sufficient EGR flow 112 is not available, controller 144 loops back to determine 504 whether a subsequent intake stroke 211 is for a donor cylinder 110. If sufficient EGR flow 112 is available, variable fuel restriction 154 provides fuel 152 to the subsequent donor and non-donor cylinders 110, and method 500 ends.

[0068] By initially providing fuel 152 to the donor cylinders 110 in response to a switch event 218 and subsequently providing fuel 152 to non-donor cylinders 110 when sufficient EGR flow 112 is available, embodiments reduce the number of cylinders 110 that fire before sufficient EGR flow 112 is available for EGR. As a result, engine knock may be reduced. Furthermore, the engine 102 may produce fewer pollutants such as nitrous oxide and operate more efficiently.

[0069] The schematic flowcharts and schematic process diagrams described above have been presented generally as logical flowcharts. Thus, the sequence and steps shown are an example of representative embodiments. Other steps, sequences, and processes may be contemplated that are functionally, logically, or effectively equivalent to one or more steps, or portions thereof, of the processes depicted in the schematic diagrams.

[0070] In addition, the format and symbols used are specified to explain the logical steps of the schematic diagrams and are not intended to limit the scope of the methods illustrated by the diagrams. Although various types of arrows and lines may be used in the schematic diagrams, they are not intended to limit the scope of the corresponding methods. Some arrows or other connecting links may even be used to indicate only the logical flow of the method. For example, an arrow may indicate a wait or monitoring period of unspecified duration between enumerated steps of a depicted method. In addition, the order in which a particular method occurs may not exactly follow the order of the corresponding steps shown.

[0071] Many of the functional units described in this specification have been referred to as modules to more specifically indicate their implementation independence. For example, a module can be implemented as a hardware circuit comprising common VLSI circuits or gate arrays, commercially available semiconductors such as logic chips, transistors, or other discrete components. Furthermore, a module can be implemented in programmable hardware devices such as field-programmable gate arrays, programmable array logic, programmable logic devices, or the like.

[0072] Modules can also be implemented in software for execution by various types of processors. For example, an identified module containing executable code may comprise one or more physical or logical blocks of computer instructions, organized, for example, as an object, a procedure, or a function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise different instructions stored in different locations that, when logically combined, comprise the module and achieve the module's stated purpose.

[0073] Indeed, a module of computer-readable program code may be only a single instruction or many instructions, and may even be distributed across several different code segments, between different programs, and across multiple storage devices. Likewise, operational data may be identified and represented herein in modules and may be embodied in any suitable form and organized in any suitable type of data structure. The operational data may be compiled as a single set of data or distributed across various locations, including across different storage devices, and may exist, at least in part, merely as electronic signals on a system or network. If a module or portions of a module are implemented in software, the computer-readable program code may be stored and / or distributed on one or more computer-readable media.

[0074] The computer-readable medium may be a tangible computer-readable storage medium that stores the computer-readable program code. The computer-readable storage medium may be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, device, or apparatus, or any suitable combination of the foregoing.

[0075] More specific examples of the computer-readable medium may include, but are not limited to, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable CD-ROM (compact disc read-only memory), a DVD (digital versatile disc), an optical storage device, a magnetic storage device, a holographic storage medium, a micromechanical storage device, or any suitable combination of the foregoing. In the context of the present disclosure, a computer-readable storage medium may be any tangible medium that can contain and / or store computer-readable program code for use by and / or in connection with an instruction execution system, apparatus, or device.

[0076] The computer-readable medium may also be a computer-readable signal medium. A computer-readable signal medium may be a propagated data signal with computer-readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electrical, electromagnetic, magnetic, optical, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium other than a computer-readable storage medium that can communicate, propagate, or transport computer-readable program code for use by and / or in connection with an instruction execution system, device, or apparatus.Computer-readable program code embodied as a computer-readable signal medium may be transmitted using any suitable medium, including, but not limited to, wireless, wired, fiber optic cable, radio frequency (RF), or the like, or any suitable combination of the foregoing.

[0077] In one embodiment, the computer-readable medium may comprise a combination of one or more computer-readable storage media and one or more computer-readable signal media. For example, computer-readable program code may be propagated as an electromagnetic signal through a fiber optic cable for execution by a processor, or stored on a RAM memory device for execution by the processor.

[0078] Computer-readable program code for performing operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, Smalltalk, C++, or the like, and conventional procedural programming languages ​​such as the "C" programming language or similar programming languages. The computer-readable program code may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server.In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).

[0079]

[0089] Throughout the specification, reference to "one embodiment" or similar expressions means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, throughout the specification, references to "in one embodiment" and similar expressions may refer to the same embodiment, but are not necessarily the same.Similarly, the use of the term "implementation" means an implementation having a particular feature, structure, or characteristic described in connection with one or more embodiments of the present disclosure, however, in the absence of an explicit correlation indicating otherwise, an implementation may be associated with one or more embodiments.

[0080] The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is therefore indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalence of the claims are intended to be embraced within their scope.

Claims

[1] Exhaust gas recirculation control device comprising: a first donor cylinder (110) and a second donor cylinder (110) of a plurality of cylinders (120, 124) in an engine (102), wherein the first donor cylinder (110) and the second donor cylinder (110) are configured to provide an exhaust gas recirculation (EGR) flow to an air intake for the plurality of cylinders, and a controller configured to control a variable fuel throttle (154) in response to an engine operating condition, wherein the variable fuel throttle (154) provides a first amount of fuel (152) concurrently with an intake stroke (211) to the first donor cylinder (110) before providing the first amount of fuel (110) to at least one non-donor cylinder (110) in response to a change from fuel withholding to the plurality of cylinders (120, 124), wherein the first fuel quantity (152) is less than a fuel quantity (152) required by the transition, wherein the variable fuel throttle (154) subsequently provides a second amount of fuel (152) to a second donor cylinder (110), and wherein the second fuel quantity (152) is a fuel quantity (152) required by the transition. [2] Device according to claim 1, characterized by that the variable fuel throttle (154) further retains the fuel (152) from at least one non-donor cylinder (110) prior to the intake stroke (211) for the first donor cylinder (110). [3] Device according to claim 1 or 2, characterized by that a torque generated by the first donor cylinder (110) is reduced by delaying the ignition of a spark plug before fuel is provided to the at least one non-donor cylinder (110). [4] Exhaust gas recirculation control method comprising the following steps: Providing exhaust gas recirculation (EGR) flow to an air intake (104) for a plurality of cylinders (120, 124) from a first donor cylinder (110) and a second donor cylinder (110) of the plurality of cylinders (120, 124), Providing a first amount of fuel (152) from a variable fuel throttle (154) concurrently with an intake stroke (211) to the first donor cylinder (110) before providing the first amount of fuel (110) to at least one non-donor cylinder (110) in response to a change from withholding the fuel (152) to the plurality of cylinders (120, 124) to providing the fuel to the plurality of cylinders, wherein the first fuel quantity (152) is less than a fuel quantity (152) required by the transition, wherein the variable fuel throttle (154) subsequently provides a second amount of fuel (152) to a second donor cylinder (110), and wherein the second fuel quantity (152) is a fuel quantity (152) required by the transition. [5] Method according to claim 4, characterized by that the variable fuel throttle (154) further retains the fuel (152) from at least one non-donor cylinder (110) prior to the intake stroke (211) for the first donor cylinder (110). [6] Method according to claim 4 or 5, characterized by that a torque generated by the first donor cylinder (110) for the first donor cylinder (110) is reduced by delaying the ignition of a spark plug before fuel (152) is provided to the at least one non-donor cylinder (110). [7] Exhaust gas recirculation control system comprising: an engine (102) comprising a first donor cylinder (110), a second donor cylinder (110), and at least one non-donor cylinder (110) of a plurality of cylinders (120, 124), wherein the first donor cylinder (110) and the second donor cylinder (110) provide an exhaust gas recirculation (EGR) flow to an air intake (104) for the plurality of cylinders (120, 124), and a controller configured to control a variable fuel throttle (154) in response to an engine operating condition, wherein the variable fuel throttle (154) provides a first amount of fuel (152) concurrently with an intake stroke (211) to the first donor cylinder (110) before providing the first amount of fuel (110) to at least one non-donor cylinder (110) in response to a change from withholding the fuel (152) to the plurality of cylinders (120, 124) to providing the fuel to the plurality of cylinders, wherein the first fuel quantity (152) is less than a fuel quantity (152) required by the transition, wherein the variable fuel throttle (154) subsequently provides a second amount of fuel (152) to a second donor cylinder (110), and wherein the second fuel quantity (152) is a fuel quantity (152) required by the transition. [8] System according to claim 7, characterized by that the variable fuel throttle (154) further retains the fuel (152) from at least one non-donor cylinder (110) prior to the intake stroke (211) for the first donor cylinder (110). [9] System according to claim 7 or 8, characterized by that a torque generated by the first donor cylinder (110) is reduced before fuel is provided to the at least one non-donor cylinder (110). [10] System according to claim 7, characterized bythat the variable fuel throttle (154) also withholds fuel from any cylinder that does not fire.

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