Engine control method and system

Abstract

Vehicle system comprising: a first vehicle which has: an engine system arranged in the vehicle and comprising an engine having a plurality of engine cylinders, each cylinder having at least one intake fuel injector and at least one direct fuel injector; at least one sensor connectable to a body of the engine to indicate cylinder combustion conditions; and a control system operable to determine an amount of a first gaseous fuel to be injected into the cylinders by the intake fuel injector and an amount of a second liquid fuel to be injected into the cylinders by the direct fuel injector based at least in part on the cylinder combustion conditions indicated by the at least one sensor; and a fuel storage vehicle connected to the first vehicle, wherein the fuel storage vehicle has a first fuel tank for storing the first gaseous fuel and the first vehicle has a second tank for storing the second liquid fuel, and wherein the vehicle system further comprises a fuel supply line connecting the first vehicle and the fuel storage vehicle for transferring the first gaseous fuel from the fuel storage vehicle to the first vehicle.

Description

BACKGROUND

[0001] Embodiments of the subject matter disclosed herein relate to a method and system for reducing uncontrolled engine combustion events. DESCRIPTION OF THE STATE OF THE ART

[0002] Vehicle engines can run on one or more fuels. These may include alternative fuels developed to alleviate the rising cost of conventional fuels and to reduce exhaust emissions. For example, a vehicle engine may be configured to operate on a compression-ignitable fuel, such as diesel, and another fuel, such as natural gas. While operating multiple fuels in the engine cylinder together can provide multiple benefits, there is also the potential for performance improvements, fuel consumption reductions, and / or exhaust emission reductions to be limited by uncontrolled combustion events.

[0003] WO 2012 / 057691 A1 discloses a dual-fuel engine operable with a gaseous and a liquid fuel. The engine comprises a supply of gaseous fuel; a supply of compression-ignitable liquid fuel; a control unit controlling the supply of gaseous fuel and liquid fuel to each combustion chamber in the engine; and at least one knock sensor arranged to transmit an output signal proportional to the detected knock level to the control unit.

[0004] US 2007 / 0 125 321 A1 discloses a system for reducing the occurrence of engine knock in engines using a dual-fuel gasification system. The system uses a knock sensor to identify early stages of engine knock. To eliminate engine knock conditions, the system temporarily interrupts the gaseous fuel flow to resume operation in full diesel mode. The gaseous fuel flow is then restored based on the current engine operating conditions.

[0005] WO 01 / 86 128 A2 discloses an internal combustion engine operable in a premixed compression ignition mode. The engine comprises an engine body with a piston assembly, a combustion chamber, an intake system, a mixing device for providing a premix of air and a first fuel, a direct fuel injector adapted for directly injecting a second fuel into the combustion chamber, and a control system for controlling the

[0006] Direct fuel injector to provide at least one early control injection of the second fuel into the combustion chamber before the start of premix combustion.

[0007] EP 1 983 169 A1 discloses an internal combustion engine having a premixture forming device that forms a premixture of fuel and air in a combustion chamber, a fuel gas supply device that injects fuel gas directly into the combustion chamber, and an ignition device that ignites the fuel gas.

[0008] US 2011 / 0 017 174 A1 discloses a system for a vehicle comprising an engine with a cylinder. The cylinder includes a fuel injector supplied with gaseous fuel and liquid fuel. The fuel injector is mounted in the vehicle such that the fuel injector inlet faces at least partially toward the road surface. The orientation of the fuel injector enables a rapid transition from liquid fuel to gaseous fuel, as the gaseous fuel can rise toward the injectors and be preferentially injected.

[0009] The invention is based on the object of expanding the performance of a conventional drive. This object is achieved by the features of the independent patent claim. The subclaims define further developments of the invention. SHORT DESCRIPTION

[0010] Methods and systems are provided for reducing uncontrolled combustion in a vehicle engine operating with a first fuel, such as a gaseous fuel, and a second fuel, such as a liquid fuel, these fuels being listed as non-limiting examples. An exemplary embodiment includes supplying a first fuel to an engine cylinder at least partially during an intake stroke, initiating combustion in the cylinder via a stratified injection of a second fuel into the cylinder, and adjusting amounts of the first fuel relative to the second fuel in the cylinder in response to an indication of uncontrolled combustion of premixed first fuel and air in the cylinder, wherein the uncontrolled combustion is initiated by the initiated combustion of the second fuel.

[0011] As used herein, uncontrolled combustion includes self-ignition of the end gases in the cylinder, which may include a mixture of the first fuel and air. Self-ignition may be caused by compression-ignition combustion of the second fuel. For example, compression-ignition combustion of stratified fuel may produce a primary flame front that increases the pressure and temperature of the remaining end gases (including a mixture of air and the first fuel) in the cylinder to the auto-ignition point. The resulting flame front of the end gases then collides with the primary flame front, generating noise and vibration as well as reduced engine torque for a given amount of the fuel.By adjusting the amounts of primary and secondary fuel in response to signs of uncontrolled combustion, it is possible to reduce self-ignition of the end gases. Leaning the air-fuel ratio of the end gas mixture reduces uncontrolled combustion and improves overall engine performance, while maintaining engine torque and / or power by appropriately increasing the amount of secondary fuel injected.

[0012] This Brief Description is intended to introduce, in a simplified form, a selection of concepts that are further described in the Detailed Description. It is not intended to identify key features or important features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that resolve any or all of the disadvantages identified in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an exemplary embodiment of a vehicle system including a first vehicle housing a vehicle engine and a second fuel storage vehicle storing a gaseous fuel. Fig. Figure 2 shows an exemplary embodiment of an engine system used in the vehicle system of Fig. 1 is used. Fig. 3-4 show high-level flow diagrams of a method for adjusting first and second fuel injection amounts in response to an indication of uncontrolled cylinder combustion. Fig. Figure 5 shows another exemplary embodiment of the engine system used in the vehicle system of Fig. 1 is used, including master and non-master cylinder groups. Fig. 6 shows a high-level flow diagram of a method for differentially adjusting the first and second fuel injection amounts in donor and non-donor cylinder groups in response to an indication of uncontrolled cylinder combustion. DETAILED DESCRIPTION

[0013] The following description relates to methods and systems for reducing uncontrolled cylinder combustion in an engine operating with multiple fuels present in the cylinder.

[0014] For example, vehicles such as the rail vehicle of the Fig. 1, can be powered by one or more fuels. For example, as in Fig. 2 and Fig. 5, the vehicle may be equipped with an engine system that can operate on both a first, gaseous fuel (such as compressed natural gas) and a second, liquid fuel (such as diesel fuel). As shown in Fig. 3, a vehicle control system may be operable to adjust fuel injection into an engine cylinder in response to an indication of uncontrolled combustion in the cylinder. In particular, in response to uncontrolled combustion of a premixed air-fuel mixture of the first gaseous fuel in the cylinder initiated by a stratified injection of the second liquid fuel, the control device may temporarily reduce the injection of the gaseous fuel while simultaneously increasing the injection of the liquid fuel in the respective cylinders. As shown in Fig. 4, based on the intensity of the indication (relative to one or more thresholds), the fuel quantity adjustment can be combined with injection timing adjustments as well as with adjustments to other engine operating parameters. In engine systems configured with donor and non-donor cylinder groups, such as the engine system in Fig. 5, differential first and second fuel injection adjustments can be made based on whether the indication of uncontrolled combustion is in a donor cylinder group or in a non-donor cylinder group ( Fig. 6). In this way, uncontrolled cylinder combustion can be reduced while simultaneously enabling fuel efficiency benefits to be achieved through the use of multiple fuels.

[0015] As used herein, gaseous fuel refers to a fuel that is gaseous at atmospheric conditions and / or after injection into the engine intake or cylinder, but which (at a pressure above saturation pressure) can be stored and / or delivered to the engine in liquid form. For example, the gaseous fuel can be stored in liquid form, delivered to the engine fuel line in liquid form, but then injected into an engine cylinder in gaseous form.

[0016] Fig. 1 shows an exemplary vehicle system, shown herein as a train 100. The train 100 includes a first vehicle 102 (shown herein as a rail vehicle, which may be a locomotive) and a second fuel storage vehicle 104 (shown herein as an inline rail vehicle). The train 100 may include one or more additional cars 106 (one of which is shown in the present example). The first vehicle 102, the second fuel storage vehicle 104, and the car 106 are configured to travel on the track 110. In alternative embodiments, any suitable number of locomotives and cars may be included in the train 100.

[0017] The first vehicle 102 is powered for propulsion, while the second vehicle 104 and the wagon 106 are not. An engine system 108 is disposed in the first vehicle 102, wherein the engine system includes an engine with multiple cylinders. Each cylinder is configured to include at least one port fuel injector and at least one direct fuel injector. In the example shown, the first vehicle 102 is configured as one of the (in Fig. 2) that operates with different fuels, such as a first fuel and a second fuel. The fuels may include a liquid fuel, such as diesel fuel, an alternative fuel, and / or a gaseous fuel, or a combination thereof. In one example, a first fuel includes a gaseous fuel and a second fuel includes diesel fuel. Further, the gaseous fuel may be an alternative fuel, such as compressed natural gas (CNG), liquefied natural gas (LNG), and / or a combination thereof.

[0018] In some embodiments, the first vehicle 102 may be powered by alternative engine configurations, such as a gasoline engine, a biodiesel engine, a natural gas engine, or a wayside (e.g., via an overhead line or third rail) powered electric motor. While the engine system 108 herein is configured in one embodiment as a multi-fuel engine operating on diesel fuel and CNG / LNG, in alternative examples, the engine system 108 may utilize a variety of fuel combinations other than diesel and CNG / LNG.

[0019] The first vehicle 102 is mechanically connected to the second fuel storage vehicle 104 by means of a coupling device 112. Similarly, the second fuel storage vehicle 104 is mechanically connected to the wagon 106 by means of a coupling device 112. In this way, the first vehicle 102, the second fuel storage vehicle 104, and the wagon 106 form a train.

[0020] The second fuel storage vehicle 104 includes a fuel system 128 having a first fuel tank 130 for storing the first (gaseous) fuel. The first vehicle 102 includes a second fuel tank (not shown) for storing the second (liquid) fuel. In an example where the vehicle system is a train, the second fuel storage vehicle may be an in-line car mechanically coupled behind a lead locomotive. As explained below, the train 100 further includes a fuel supply line 136 connecting the first vehicle 102 and the second fuel storage vehicle 104 for transferring the first, gaseous fuel from the fuel storage vehicle to the first vehicle.

[0021] The first fuel tank 130 is configured to store the first fuel in either a liquid or gaseous state. As shown in Fig. 2, the first fuel may be a gaseous fuel stored in the first fuel tank 130 at saturation pressure, and the fuel system 128 may be configured as a liquid phase injection (LPI) system, wherein the gaseous fuel is delivered to an engine fuel line at a pressure elevated relative to atmospheric pressure. In one example, the first fuel may be compressed natural gas (CNG) or liquid propane (LPG) fuel. Herein, in the example of a liquid phase injection system, the fuel may be in liquid form (e.g., as LNG) when stored at saturation pressure in the fuel tank 130 carried by the fuel storage vehicle 104 and while the fuel is delivered along a fuel line and a fuel injection line at high pressure.However, when injected into the engine at a lower pressure by means of the injectors into the cylinder (e.g., into a fuel preparation area of ​​the engine having a lower pressure (compared to the line pressure)), the fuel may transition to a gaseous form and thus be injected in a gaseous state. By maintaining the fuel at high pressure and in liquid form during at least part of the delivery along the fuel line and into the fuel injection line, fuel metering is facilitated. However, in a further embodiment, the fuel injection line may carry the fuel in a gaseous state.

[0022] In an exemplary embodiment, CNG or LNG is stored in the second fuel storage vehicle 104 (e.g., in a tender car) on a platform system 131. The platform system 131 is configured to regulate and control a temperature and pressure of the gaseous fuel. Various filters, valves, intercoolers, and control systems (as detailed herein) may be mounted near the fuel tank (e.g., adjacent to the fuel tank) in the platform system. The platform system may further be connected to the locomotive 102. The platform system may, for example, include the fuel supply line.

[0023] Various fuel system components, such as various valves, pressure regulators, filters, and sensors, may be connected in the fuel system 128, including a tank isolation valve 132 that controls the entry of fuel from the fuel tank 130 into the fuel supply line 136, and a pressure regulator 134 that regulates the fuel line pressure of the first gaseous fuel. As discussed herein, an initial (unadjusted) amount of the first fuel and the second fuel supplied to the engine, as well as an initial ratio of the first fuel with respect to a second fuel, may be determined based at least in part on a power level setting of the vehicle engine. The second fuel used herein may be a liquid fuel, such as diesel.The initial, unadjusted amounts of the first and second fuels are injected before an indication of uncontrolled combustion is received. Then, in response to an indication of uncontrolled combustion in the cylinder, the first and / or second fuel amounts may be adjusted to reduce the uncontrolled combustion.

[0024] A vehicle control system or control device 12 may be configured to receive information from and transmit signals to the first vehicle 102 and the second vehicle 104 of the train 100. The control device 12 may, as described herein, receive signals from a variety of sensors on the train 100 regarding engine and / or vehicle operating conditions and may adjust vehicle and engine operation accordingly. For example, the control device 12 may be operable to determine an amount of fuel to be injected from each of a plurality of fuel sources into each engine cylinder. The control device may then further adjust the amounts of fuel injected into the engine cylinders in response to an indication of uncontrolled combustion and / or in response to the vehicle operating (or beginning to operate) in a defined state.In one example, the control device 12 may be located in a local environment, such as on board the first vehicle 102. However, in an alternative example, the control device 12 may be at a remote location, such as in a train dispatch center.

[0025] The motor system generates torque 108, which is used by a system generator (not shown) to generate electricity for subsequent propulsion of the train 100. Traction motors (not shown) mounted on a chassis 135 beneath the first vehicle 102 provide tractive effort for propulsion. In one example shown herein, six inverter traction motor pairs may be provided for all six axle wheel pairs 111 of the first vehicle 102. The traction motors may also be configured to act as generators, achieving dynamic braking to decelerate the first vehicle 102. In particular, during dynamic braking, each traction motor may provide torque in a direction opposite to the torque required to propel the first vehicle in the rolling direction, thereby generating electrical power.At least a portion of the generated electrical power may be directed to an electrical energy storage device of the system, such as a battery (not shown). Air brakes 114, which utilize compressed air, may also be used by the first vehicle 102 for braking.

[0026] The operating crew and electronic components used in the vehicle control and management system, such as an on-board diagnostic (OBD) system 116, may be housed in the driver's cab 118. The OBD system 116 may communicate with the control device 12, for example, via a wired or wireless communication 180 (not shown).

[0027] A vehicle operator may also indicate a desired vehicle power level by adjusting a power level setting of the vehicle engine. In one example, the vehicle operator may adjust a power level setting of the train 100 (thereby also controlling the vehicle speed and torque demand) by adjusting the accelerator pedal and / or brake settings. For example, the first vehicle 102 may be configured with a stepped or "detented" accelerator pedal (not shown) having multiple accelerator pedal positions or "detents," including an idle detents corresponding to idle engine operation and multiple power detents corresponding to progressively more powerful engine operation. The accelerator pedal may additionally have progressively dynamic brake detents for progressively higher braking demands. When in an idle power setting (e.g.,the idle detent position), the engine system 108 may receive a reduced amount of total fuel from the multiple fuel sources, enabling it to idle at low rpm. Additionally, the traction motors may not be activated. To begin operation of the first vehicle, the vehicle operator may select a direction of travel by adjusting the position of the direction reverser 121, which may be set to a forward, reverse, and neutral position. After setting the reverser in either a forward or reverse direction, the vehicle operator may release the brake 114 and move the accelerator pedal to a first low power level setting (e.g., to a first power detent) to activate the traction motors. When the power level setting is increased (e.g.,when the accelerator pedal is moved to the higher power detents), the fuel rate and total amount of fuel supplied to the engine is increased, resulting in a corresponding increase in power output and vehicle speed.

[0028] The train 100 may include various sensors for determining vehicle and engine operating conditions and communicating them with the OBD system 116 and / or the controller 12. The various sensors may include at least one combustion sensor 140 and one crankshaft sensor 142 connected to a body of the vehicle's engine. The combustion sensor is configured to provide an indication of cylinder combustion conditions, including an indication of uncontrolled combustion in a cylinder. The crankshaft speed sensor is configured to provide an indication of crankshaft speed. The controller 12 may determine an indication of uncontrolled combustion in a given cylinder based on the outputs it receives from both the combustion sensor 140 and the crankshaft speed sensor 142.Other sensors on board the train 100 include rail sensors (for providing an indication of track conditions, such as rail grade), location sensors (for providing an indication of the location of the train and geographical markers, such as tunnels and bridges, at or near the train's location), various temperature and pressure sensors (for providing an indication of vehicle, engine, fuel tank, and ambient temperature and pressure conditions), particulate matter sensors (for providing an indication of dust or soot levels at the train's location), etc. The controller 12 receives input data from the various sensors, processes the input data, and controls various actuators in response to the processed data based on instructions or codes programmed therein that correspond to one or more routines.The various actuators may include fuel injectors, accelerator pedals, various valves (such as tank shutoff valve 132), various pressure regulators (such as pressure regulator 134), etc. Example control routines are described herein with reference to FIG. Fig. 3, Fig. 4 and Fig. 6 described.

[0029] In one example, the control system is operable to determine an amount of a first, gaseous fuel to be injected by intake fuel injectors into a plurality of engine cylinders and an amount of a second, liquid fuel to be injected by direct fuel injectors into the plurality of engine cylinders based at least in part on cylinder combustion conditions indicated by at least one combustion sensor and a power stage setting.The control system is then further operable to change the amount of first fuel injected into the at least one of the plurality of cylinders in response to an indication of the combustion condition, the change comprising a decrease in the amount of first fuel injected by the intake fuel injectors and a corresponding increase in the amount of second fuel injected by the direct fuel injectors.

[0030] Fig. 2 shows a detailed illustration of an engine system 200. In one example, the engine system 200 is in a vehicle system, such as the vehicle system of the Fig. 1. The engine system 200 includes a control system 214 and a fuel system 218. The engine system 200 may include an engine 210 having a plurality of cylinders 230. The engine 210 includes an engine intake 223 and an engine exhaust 225. The engine intake 223 includes a throttle valve 262 fluidly coupled to the engine intake manifold 244 via an intake runner 242. The engine exhaust 225 includes an exhaust manifold 248 leading to an exhaust passage 235 that directs exhaust gas through an emissions control device 270 to the atmosphere. Note that other components, such as various valves and sensors, may be housed within the engine.

[0031] The engine system 200 is shown as a supercharged internal combustion engine including a turbocharger with a compressor 272 driven by an exhaust turbine 274. Operation of the turbocharger enables boosted engine operation. In alternative embodiments, the engine system 200 may be configured with a supercharger. The engine system is also shown with an exhaust gas recirculation (EGR) system for recirculating an amount of exhaust gas from the engine exhaust to the engine intake. In particular, the engine system 200 is shown with an EGR passage 295 coupled upstream of the compressor 272 and downstream of the turbine 274. By adjusting a position of an EGR valve 296 in the EGR passage 295, an amount of low-pressure EGR may be delivered. In other embodiments, high pressure EGR may also be enabled, with the EGR passage coupled downstream of the compressor 272 and upstream of the turbine 274.

[0032] The fuel system 218 includes one or more fuel tanks. In the example shown, the fuel system is a multi-fuel system including a first fuel tank 220a configured to deliver a first fuel having a first chemical and physical property along a first fuel line 252, and a second fuel tank 220b configured to deliver a second fuel having a different second chemical and physical property along a second fuel line 254. Various fuel system components, such as various valves, pressure regulators, filters, and sensors, are coupled along each of the first fuel line 252 and the second fuel line 254. The fuel tanks 220a, 220b hold multiple fuels or fuel blends.For example, the first fuel stored in the first fuel tank 220a may be a gaseous fuel, such as compressed natural gas (CNG), while the second fuel stored in the second fuel tank 220b may be a second liquid fuel, such as diesel. In one example, as shown in FIG. Fig. As shown in Figure 1, the engine 210 may be mounted on a first vehicle of a vehicle system, while the first fuel tank 220a, which stores the first gaseous fuel, may be mounted on a second vehicle of a vehicle system, the second vehicle being mechanically coupled to the first vehicle. The second fuel tank 220b, which stores the second liquid fuel, may be mounted with the engine on the first vehicle of the vehicle system.

[0033] Each fuel tank may be coupled to respective fuel pumps for compressing fuel supplied to the injectors of the engine 210, such as injectors 266 and 268. While only a single set of injectors 266, 268 is shown, additional sets of injectors are provided for each cylinder 230. In the example shown, the first fuel stored in the first fuel tank 220a is supplied to a first intake fuel injector 266 of the engine cylinder 230 via a first fuel line 223a, while the second fuel in the second fuel tank 220b is supplied to a second direct fuel injector 268 of the engine cylinder 230 via a second fuel line 223b.However, in alternative examples, each of the injectors 266, 268 may be configured as a direct fuel injector, with each of the first and second fuels being delivered to the engine cylinder via a direct fuel injector. The fuel system may further include one or more valves (not shown) for regulating the supply of fuel from the fuel tank 220a to the injector 266 and from the fuel tank 220b to the injector 268.

[0034] In the example shown, the first fuel line 252 and associated components are configured to supply the first gaseous fuel. Accordingly, the first fuel tank 220a is coupled to a pressure regulator 234 and a solenoid valve 236 to enable a fixed low-pressure supply of the first fuel to be supplied to the injector 266. A tank valve 232 (e.g., a check valve) is disposed between the first fuel tank 220a and the pressure regulator 234 to ensure proper flow of fuel from the fuel tank. A tank outlet line pressure sensor 233 is disposed upstream of the pressure regulator 234 and downstream of the first fuel tank 220a to provide an estimate of the fuel pressure prior to pressure regulation by the pressure regulator 234. The pressure sensor 233 may, for example, provide an estimate of the fuel inlet pressure to the high-pressure side of the pressure regulator 233.A coalescing filter 238 is arranged on the low-pressure side of the pressure regulator 234. The solenoid valve 236, referred to as a shut-off valve, may be coupled between the pressure regulator 234 and a coalescing filter 238.

[0035] In one example, the first fuel tank 220a stores the gaseous fuel at a pressure range of 10-220 bar (e.g., 3000-6000 psi for a CNG fuel), while the pressure regulator 234 regulates the fuel line pressure to a fixed range of 3-10 bar (e.g., 2-10 bar for a CNG fuel). Another check valve (not shown) may be coupled downstream of the pressure regulator 234 and upstream of the fuel injector 266. The fuel system 218 itself may be a returnless fuel system, a recirculation fuel system, or various other types of fuel system. It will be appreciated that although the embodiment shows the fuel system 218 as a dual-fuel system, in alternative embodiments, the fuel system 218 may include other additional fuels.

[0036] The engine system 200 further includes a control system 214. The control system 214 is shown receiving information from a plurality of sensors 216 (various examples of which are described herein) and sending control signals to a plurality of actuators 281 (various examples of which are described herein). The sensors 216 may include, for example, MAP and MAF sensors 284 and 285 in the intake, an exhaust gas sensor 286 and temperature sensor 227 located in the exhaust, pressure sensors 202, 204 coupled to the first and second fuel lines, respectively, and configured to provide an estimate of the respective fuel line pressures, pressure sensors 292, 294 coupled to the first and second fuel tanks, respectively, and configured to provide an estimate of the respective fuel tank pressures, etc. Other sensors, such asPressure, temperature, fuel level, air / fuel ratio, and composition sensors may be coupled to various locations in the engine system. For example, a combustion sensor 228 and a crankshaft speed sensor (not shown) may be connected to the engine block to provide an indication of cylinder combustion conditions. For example, combustion sensor 228 may provide an indication of uncontrolled combustion in a cylinder based on block vibration signals during predefined crankshaft angle windows. As another example, the actuators may include fuel pumps (221a and 221b), fuel injectors 266, 268, a solenoid valve 236, a pressure regulator 234, and a throttle valve 262.The control system 214 may include a controller 212 that receives input data from the various sensors, processes the input data, and controls the actuators in response to the processed input data.

[0037] In one example, the controller may receive information about cylinder combustion conditions of a plurality of cylinders of an engine and port-inject respective first amounts of a first gaseous fuel into the cylinders during intake strokes of the cylinders while simultaneously directly injecting respective second amounts of a second liquid fuel into the cylinders. The controller may then control the first amounts and the second amounts based on the received information about the cylinder combustion conditions.

[0038] It will now Fig. 3, an example routine 300 is provided for adjusting an amount of a first gaseous fuel and / or an amount of a second liquid fuel delivered to a cylinder of a vehicle engine in response to an indication of uncontrolled combustion in the engine cylinder. The adjustment enables the reduction of uncontrolled combustion of a relatively homogeneous mixture of air and the first fuel in the cylinder, initiated by the combustion of a stratified mixture of air and the second fuel in the cylinder.

[0039] At 302, engine and vehicle operating conditions are estimated and / or measured. These include, for example, engine speed, vehicle speed, engine temperature, exhaust catalyst temperature, ambient conditions (e.g., ambient temperature, ambient humidity, ambient soot or dust levels, barometric pressure, altitude, etc.), boost pressure, desired power level, driver-specified torque demand, etc.

[0040] At 304, injection quantities for a first, gaseous fuel and a second, liquid fuel are determined based on the estimated operating conditions. For example, a vehicle control system may be operable to determine a first amount of the first fuel and a second amount of the second fuel. The control system may also determine a ratio of the first fuel to the second fuel in a total fuel amount.

[0041] The first fuel may in itself be a first, non-compression-ignitable fuel. A relatively homogeneous mixture of the first fuel and air in the cylinder may be ignited, for example, by actuating a spark plug. The first fuel may comprise a gaseous fuel, such as natural gas (e.g., compressed natural gas (CNG), liquefied natural gas (LNG), etc.). As used herein, a gaseous fuel refers to a fuel that is gaseous at atmospheric conditions, but at high pressure (particularly above saturation pressure) may be present in liquid form in the fuel system. In other words, the first fuel is injected into the engine (at lower pressure) in gaseous form, but is stored and delivered in liquid form (at higher pressure). In one example, as described in Fig. 1, the vehicle engine may be disposed within a first vehicle, and the first fuel may be stored in a second vehicle that is mechanically coupled to the first vehicle. In comparison, the second fuel is a second compression-ignitable fuel. For example, a stratified charge mixture of the second fuel and air in the cylinder is ignited toward the top of the compression stroke using heat from compression in the cylinder. The second fuel may comprise a liquid fuel, such as diesel.

[0042] The first and second fuel quantities to be injected into the engine cylinders may be based at least in part on the engine's power level setting. The fuel quantities may also be based at least in part on cylinder combustion conditions indicated by at least one combustion sensor. For example, if the engine is located within a rail vehicle, a desired power level (or operating torque requirement) may be derived from a power level setting, such as a detent setting of a detented accelerator pedal of the rail vehicle, as set by a vehicle operator.The control system may determine an initial fuel injection ratio with adjusted amounts of the first, gaseous fuel and the second, liquid fuel for injection into a cylinder based on the power level setting of the vehicle, prior to receiving any indication of uncontrolled combustion.

[0043] At 306, the routine includes delivering the first fuel to an engine cylinder at least partially during an intake stroke. The first fuel delivered to the engine cylinder may comprise a gaseous fuel, such as CNG. Delivering the first fuel includes delivering the first gaseous fuel. Delivering the first fuel to the cylinder may further include port injection of the first fuel into the cylinder. The control system may port inject the first amount of the first compression-non-ignitable (gaseous) fuel into the engine cylinder at least partially during an intake stroke (e.g., earlier during an intake stroke) to provide a relatively homogeneous mixture (or charge) of the first fuel and air within the cylinder. The first gaseous fuel may, for example, be injected along with air at least partially during the intake stroke.For example, the first fuel and air may be premixed for approximately 10 crankshaft angle degrees (CAD) to create a relatively homogeneous mixture. While the above recommends port injection of the first fuel, it will be appreciated that the delivery of the first fuel may alternatively include direct injection of the first gaseous fuel at least partially during the intake stroke.

[0044] Next, at 308, the routine includes initiating combustion in the cylinder via a stratified injection of the second (liquid) fuel into the cylinder. The second fuel is injected during a compression stroke, such as at top dead center (TDC). Supplying the second fuel to the cylinder includes direct injection of the second fuel into the cylinder. In particular, the control system may directly inject the second amount of compression-ignitable second (liquid) fuel into the cylinder to create a stratified mixture (or charge) of the second fuel and air within the cylinder.Once combustion of the second fuel has been initiated via compression ignition, the initiated combustion of the stratified cylinder charge (composed of the second fuel and air) can then initiate combustion of the homogeneous charge (composed of the first fuel and air). The second fuel injected into the cylinder to initiate combustion can comprise a liquid fuel, such as diesel.

[0045] During some engine operating conditions, uncontrolled combustion of the homogeneous cylinder charge may be initiated by the initiated combustion of the second fuel. The uncontrolled combustion comprises self-ignition of the end gases in the cylinder, which may comprise a mixture of the first fuel and air. The self-ignition is caused by compression-ignition stratified combustion of the second fuel. For example, compression-ignition stratified combustion of the liquid fuel may create a primary flame front that increases the pressure and temperature of the remaining end gases (comprising a mixture of air and the gaseous first fuel) in the cylinder to the auto-ignition point. The resulting flame front of the end gases then collides with the primary flame front, generating noise and vibration, as well as reduced engine torque for a given amount of the fuel.Accordingly, at 310, the routine determines whether there is an indication of uncontrolled combustion of the homogeneous mixture of the first fuel and air in any cylinder. In one example, one or more sensors (e.g., combustion sensors) may be coupled to a body of the engine to indicate cylinder combustion conditions. Uncontrolled combustion may be determined based on the one or more sensors relative to a threshold. For example, if the output of the one or more sensors is higher than the threshold, uncontrolled combustion may be confirmed. Additionally, based on the output of a crankshaft speed sensor (coupled to an engine block) relative to the cylinder combustion indication from the one or more (combustion) sensors, the identity of a cylinder (or cylinders) in which the uncontrolled combustion occurred may be determined.

[0046] If no indication of uncontrolled combustion is received, the routine may end with the control system injecting the determined (unadjusted) amounts of the first and second fuels into the engine. The unadjusted amounts are injected per se before an indication of uncontrolled combustion is received. If uncontrolled combustion is indicated based on the output of each of a combustion sensor and a crankshaft sensor coupled to an engine block of the vehicle, the routine then includes adjusting the amounts of the first gaseous fuel and the second fuel in the cylinder at 312.The fuel injection amounts are adjusted in response to a first indication of runaway combustion of a premixture of the first, gaseous fuel and air in the cylinder, the runaway combustion having been initiated by the combustion of the second fuel (injected using stratified injection). The adjustment includes changing the amount of first injected fuel and changing the amount of second fuel injected into a cylinder in response to the first indication of runaway combustion in the given cylinder, while maintaining cylinder output torque and while also maintaining an air-fuel ratio of the cylinder at a level at which it accommodates relatively more air (e.g., more by weight, more by volume, etc.).) as total fuel is present to consume the air during combustion of the entire amount of fuel. For example, the cylinder air-fuel ratio may be leaner than stoichiometric. The adjustment in 312 may include a decrease in an injection amount of the first gaseous fuel in 313 and an increase in an injection amount of the second, liquid fuel in 314 in corresponding amounts. The magnitude of the decrease in the first fuel may, for example, be balanced by the magnitude of the increase in the second fuel. While the actual mass amounts of the decrease in the first fuel and the increase in the second fuel may be different (due to the different stoichiometric combustion ratios of the first and second fuels), the amounts may be selected to maintain the overall combustion torque level. For example,At current operating conditions, a pre-stored ratio can be used that results in a relatively constant torque level with corresponding reductions / increases in the respective first and second fuel.

[0047] In one example, reducing an injection quantity of the first fuel comprises maintaining an injection start time of the first fuel while simultaneously advancing an injection end time of the first fuel in order to shorten a total injection duration of the first fuel. Similarly, increasing an injection quantity of the second fuel comprises maintaining a start of the injection timing of the second fuel while simultaneously delaying an injection end time of the second fuel in order to extend a total injection duration of the second fuel. However, in some embodiments, the injection timing start of the second fuel, as in Fig. 4. Increasing an injection quantity of the second fuel may further include adjusting an injection timing of the stratified fuel injection in response to the indication of uncontrolled combustion such that it occurs later with respect to a crankshaft position. The injection timing (e.g., the start of the injection time) of the second fuel may, for example, be delayed from an earlier time during the compression stroke to a later time during the compression stroke or from the compression stroke to the expansion stroke.

[0048] In one embodiment, controlling the first and second fuel injection amounts in response to the indication of runaway combustion is selectively performed cylinder by cylinder based on one or more cylinders in which runaway combustion has been indicated. For example, adjusting fuel injection amounts is performed only in those cylinders determined to be affected by runaway combustion. However, in alternative embodiments, if the indication of runaway combustion is higher than an upper threshold, the adjustment may be extended to all engine cylinders, including those not determined to be affected by runaway combustion, so as to mitigate potential runaway combustion in those cylinders (e.g., in anticipation of potential runaway combustion events).

[0049] In some embodiments, the fuel injection amounts may be adjusted based on the vehicle operating in a defined condition. When the vehicle begins operating in the defined condition (e.g., when the vehicle has just begun operating in the defined condition) or is about to begin operating in a defined condition (e.g., when the vehicle is a threshold distance or time away from operating in the defined condition), the control system may further vary the amount of the first fuel and / or the second fuel in anticipation of uncontrolled cylinder combustion events. Then, when the defined condition ends, the original (i.e., unadjusted) fuel injection amounts may be resumed. For example, the fuel amounts may be adjusted in response to a position of the vehicle relative to a tunnel (e.g.,when the vehicle is in a tunnel or the vehicle is approaching a tunnel and is less than a threshold distance or a threshold time period from entering the tunnel). The adjustment may comprise a further reduction in the injection amount of the first fuel and / or a further increase in the injection amount of the second fuel. When the vehicle enters a tunnel, the amount of fresh intake air available to the engine may simply be limited, and an amount of exhaust gas recirculation may be artificially increased (due to the vehicle exhaust being drawn into the engine intake port when the vehicle is traveling in the tunnel). Here, the fuel amounts are reduced in anticipation of potential uncontrolled combustion events resulting from the temporary increase in external exhaust gas recirculation and temporary reduction in fresh air availability.

[0050] As another example, the defined vehicle operating condition to which fuel injection amounts are responded to by adjusting the fuel injection quantities may include a change in altitude and / or barometric pressure. When the vehicle reaches an uphill or downhill segment, the fuel injection amounts may be appropriately adjusted, with the direction of the adjustment based on whether the vehicle is traveling uphill or downhill. Still other defined vehicle operating conditions to which fuel injection amounts may be responded to by adjusting the fuel injection quantities include changes in ambient temperature (e.g., when the vehicle is operating in warmer or cooler regions), changes in ambient soot or dust levels (e.g., when the vehicle is operating in dustier regions), etc.

[0051] In this way, by controlling the first and / or second fuel injection amount while maintaining cylinder output torque in response to an indication of uncontrolled combustion of a relatively homogeneous charge mixture (of a first, gaseous fuel and air) initiated by compression ignition of a stratified mixture (of a second, liquid fuel and air), uncontrolled combustion can be better reduced and engine performance with the first, gaseous fuel is improved.

[0052] It will now Fig. 4, which shows another example routine 400 for changing fuel injection adjustments in response to an indication of runaway cylinder combustion based on an intensity (e.g., magnitude) of the indication. By adjusting one or more engine operating parameters in addition to cylinder fuel injection amounts as the indication of runaway combustion exceeds progressively higher thresholds, runaway combustion may be better mitigated. Additionally, the likelihood of further runaway combustion events may be reduced.

[0053] At 402, the routine includes confirmation that an indication of uncontrolled combustion is present. As described above with reference to Fig. 3, an indication of uncontrolled combustion as well as an identity of the affected cylinder(s) may be determined based on both a combustion sensor output and a crankshaft speed sensor output. If uncontrolled combustion is confirmed in a cylinder, then the routine includes, in 404, determining whether the indication of uncontrolled combustion is higher than a first threshold (Threshold1). For example, an absolute magnitude of the indication of uncontrolled combustion (such as the sensor output) is compared to the first threshold. If the indication is not higher than the first threshold, then the routine includes, in 406, adjusting the first and second fuel injection amounts in the affected cylinder. As with Fig. 3, a first amount of fuel supplied to the affected cylinder is reduced, while a second amount of fuel supplied to the affected cylinder is correspondingly increased to reduce runaway combustion while maintaining engine output torque and the air-fuel ratio. This involves maintaining a start of injection timing of both the first and second fuels, but advancing an end of the injection timing of the first fuel (to decrease an injection duration of the first fuel) while simultaneously delaying the end of the injection timing of the second fuel (to increase the injection duration of the second fuel).

[0054] If the indication is higher than the first threshold at 404, then at 408 it may be further determined whether the indication is higher than a second threshold (Threshold2), where the second threshold is higher than the first threshold. For example, the absolute magnitude of the indication of runaway combustion (such as the sensor output) is compared to the second threshold. If the indication is higher than the first threshold but not higher than the second threshold, then at 410 the routine includes (as explained above at 406) adjusting the first and second amounts of fuel in the affected cylinder while simultaneously retarding an injection timing of the second fuel to be later with respect to a crankshaft position.For example, in addition to decreasing the injection of the first fuel and increasing the injection of the second fuel, an injection timing of the second fuel is retarded from an earlier time during the compression stroke to a later time during the compression stroke (or into the expansion stroke). Specifically, in addition to adjustments to the end of the injection timing of each of the first and second fuels (as described above at 406), a start of an injection timing of the second fuel is retarded while maintaining the start of the injection timing of the first fuel.

[0055] If the indication is higher than both the first and second thresholds, then in 412, in addition to adjusting the first and second injection amounts and retarding the injection timing of the second fuel (as described above at 410), the routine includes adjusting one or more engine operating parameters. For example, if the engine is operating with boost, the boost level is reduced. As another example, if the engine is operating with exhaust gas recirculation (EGR), the EGR level is reduced. This may include adjusting a valve position of an EGR valve to reduce the amount of fuel injected from the engine exhaust to the engine intake via an EGR passage (such as the EGR valve and EGR passage in Fig. 2) to reduce recirculated exhaust gas.

[0056] One will realize that while the routine in Fig. 4 illustrates control of the first and second fuel injection amounts in response to the indication of runaway combustion, selectively performed cylinder-by-cylinder based on the affected cylinder(s) for which runaway combustion has been indicated. In some embodiments, when the indication of runaway combustion is higher than the first threshold and / or the second threshold, in anticipation of potential runaway combustion events, the adjustment may be extended to all engine cylinders, including those not determined to be affected by runaway combustion. For example, at 410 and / or 412, the fuel injection amount adjustment and the fuel injection timing adjustment may be extended to the unaffected cylinders.In yet further embodiments, the number of unaffected cylinders to which the adjustments are extended may be adjusted based on a difference between the indication of uncontrolled combustion and the first and / or second threshold. Thus, if the indication of uncontrolled combustion exceeds the first and / or second threshold, the number of unaffected cylinders to which the adjustment is extended may be increased.

[0057] In one example, a vehicle system (e.g., a train) includes a first vehicle (e.g., a locomotive) mechanically coupled to a second fuel storage vehicle (tandem car). The first vehicle houses a vehicle engine operable with a first gaseous fuel (e.g., compressed natural gas (CNG)) and a second liquid fuel (e.g., diesel). The second vehicle houses a fuel tank storing the first gaseous fuel at elevated pressure, with the fuel at lower pressure being deliverable to and used in the engine. Based on engine operating conditions, including a power setting (e.g., a detent setting) of the engine, an engine controller estimates a first fuel quantity of the first CNG fuel and a second fuel quantity of the second diesel fuel for injection into each cylinder.The CNG fuel is injected into the intake port early during an intake stroke to enable sufficient air-fuel mixing in the cylinder and the creation of a homogeneous air-charge mixture. During the compression stroke, diesel fuel is then injected (e.g., as a cylinder piston approaches TDC) to create a stratified air-charge mixture. Compression ignition of the stratified air-fuel mixture then initiates combustion of the premixed homogeneous air-charge mixture.

[0058] During selected conditions, the stratified combustion of the diesel fuel can lead to the uncontrolled combustion of the homogeneous air-charge mixture (comprising the CNG fuel). In response to an indication of uncontrolled combustion, as detected by combustion sensors that can be coupled to the engine block, an engine control system immediately adjusts the first and second fuel injection amounts in the cylinder(s) affected by the uncontrolled combustion. Specifically, the amount of injected CNG fuel is reduced, and the amount of diesel fuel is increased accordingly. The fuel injection adjustment continues until the indication of uncontrolled combustion has subsided.

[0059] It will now Fig. 5, an alternative embodiment of an engine system 502 coupled to the vehicle 500 is shown. The vehicle 500 may include, as non-limiting examples, a locomotive, a vessel, an off-road vehicle, etc. The engine system 502 includes a plurality of cylinders 504. The plurality of cylinders 504 are organized into one or more donor cylinder groups and one or more non-donor cylinder groups. In particular, the engine system 502 includes a first cylinder group 506 including at least a first cylinder and a second cylinder group 508 including at least a second cylinder. Note that "first" and "second" are terms used to identify the cylinders of the first and second cylinder groups, respectively.

[0060] The first cylinder group 506 includes at least one donor cylinder that provides exhaust gas routed to an intake manifold 510 of the engine system 502. (The intake manifold refers to a passage or passages connected to cylinder input ports for providing intake air to the cylinders.) The second cylinder group 508 includes at least one non-donor cylinder that provides exhaust gas routed to an exhaust pipe 514. In the illustrated implementation, the first cylinder group 506 includes one donor cylinder that provides only exhaust gas to the intake manifold 510, and the second cylinder group 508 includes three non-donor cylinders that provide only exhaust gas to the exhaust pipe 514. It will be appreciated that each of the cylinder groups may include any suitable number of cylinders. Further, the engine system may include any suitable number of donor cylinder groups and non-donor cylinder groups.In some implementations, a donor cylinder group may selectively deliver exhaust gas to an intake manifold and to an exhaust pipe by actuating a valve or other control device.

[0061] The intake manifold 510 is connected to the first cylinder group 506 and the second cylinder group 508. An intake passage 512 provides fresh air to the intake manifold 510 for combustion. Specifically, air enters the intake passage 512 from ambient and passes through a compressor 516 of a turbocharger 520. In the illustrated implementation, the engine system 502 does not include a throttle valve disposed within the intake passage 512. However, in some implementations, the intake passage 512 may include a throttle valve disposed downstream of the compressor 516.

[0062] The turbocharger 520 includes a compressor 516 connected to a turbine 518. The turbine 518 is disposed in the exhaust pipe so that exhaust gas supplied from the second cylinder group 506 causes the turbine 518 to rotate. The rotation of the turbine 518 drives the compressor 516, compressing air flowing through the intake passage 512 to increase the mass of air flowing into the intake manifold 510 or to increase the pressure within the intake manifold 510.

[0063] Each of the plurality of cylinders 504 includes at least one intake port 522 operable to receive combustion air from the intake manifold 510 and at least one exhaust port 524 operable to expel gas into an exhaust manifold. A first exhaust manifold 526 is coupled to the first cylinder group 506 to receive exhaust gas from the first cylinder group 506. The first exhaust manifold 526 is not coupled to the second cylinder group 508. An EGR passage 530 is coupled between the first exhaust manifold 526 and the intake passage 512. The EGR gas flows through the EGR passage 530 into the intake passage 512, where it mixes with the fresh intake air, and the mixed air is compressed by the compressor 516. The mixture of EGR gas and fresh air flows through the intake manifold 510 and is directed to the first cylinder group 506 and the second cylinder group 508.The EGR passage 530 is not coupled to the second exhaust manifold 528 of the second cylinder group 508. In some implementations, an EGR valve is disposed in the EGR passage 530 to control the EGR mass flow rate through the EGR passage in addition to controlling the EGR composition through active fuel control of the donor cylinder group. In some implementations, the EGR passage 530 does not include an EGR valve or other device to vary a flow rate of the EGR gas supplied to the intake manifold 510.

[0064] A second exhaust manifold 528 is coupled to the second cylinder group 508 to receive exhaust gas from the second cylinder group 508. The second exhaust manifold 528 is not coupled to the first cylinder group 506. The second exhaust manifold 528 is coupled to the exhaust pipe 514. Exhaust gas supplied from the second cylinder group 508 flows from the second exhaust manifold 528 through the turbine 518 of the turbocharger 520 to the exhaust pipe 514. Various aftertreatment devices (not shown) may be provided in the exhaust pipe 514 before and after the turbine 518 to treat the exhaust gas before it is released to the atmosphere.

[0065] A first set of fuel injectors 532 is shown directly coupled to the plurality of cylinders 504 for injecting fuel directly therein proportional to a pulse width of a signal from a controller 534. In this manner, the plurality of fuel injectors 532 provide what is known as direct injection of fuel into the plurality of cylinders 504. Additionally, a second set of fuel injectors 533 is shown coupled to an intake port of the plurality of cylinders 504 for injecting fuel into the intake port of each cylinder proportional to a pulse width of a signal from a controller 534. In this manner, the plurality of fuel injectors 533 provide what is known as port injection of fuel into the plurality of cylinders.Each of the plurality of fuel injectors 532, 533 is independently operable to inject fuel into one of the plurality of cylinders 504. Each of a first fuel, such as a first gaseous fuel, and a second fuel, such as a second liquid fuel, may be delivered to the cylinder via the plurality of fuel injectors 532, 533 from a fuel system (not shown) that includes a fuel tank, a fuel pump, and a fuel rail. In one example, as described above with reference to FIG. Fig. 2, the controller 534 may inject the first (gaseous) fuel into the cylinders and directly inject the second (liquid) fuel.

[0066] The controller 534 receives various signals from the sensors 540 coupled to the engine system 502. The controller 534 may be configured to control exhaust gas recirculation (EGR) based at least in part on the signals. For example, the controller 534 receives sensor signals indicative of the air-fuel ratio, engine speed, engine load, engine temperature, ambient temperature, intake manifold temperature, exhaust gas temperature, intake manifold pressure (boost pressure), exhaust gas pressure, ambient altitude, oxygen concentration in the intake manifold, runaway combustion, etc. In the illustrated implementation, the controller 534 is a computing device, such as a microcomputer, including a processor unit 536, a non-transitory computer-readable storage medium device, input / output ports, a data bus, etc.The computer-readable storage medium device 538 is programmable with computer-readable data representing instructions executed by the processor unit to perform methods described below, as well as other expected but not specifically listed variations of the methods.

[0067] The controller 534 is operable to adjust various actuators in the engine system 502 based on various operating parameters received or derived from various signals received from the plurality of sensors 540. For example, the controller 534 is operable to determine a planned oxygen concentration in the donor cylinder group. The planned oxygen concentration may be a predicted or a target oxygen concentration achieved through a closed-loop control system. The planned oxygen concentration may be determined in any suitable manner. For example, various operating conditions based on engine speed, engine load, engine temperature, boost pressure, etc., may be mapped to a planned oxygen concentration (e.g., in a lookup table) that is delivered to all engine cylinders.Furthermore, controller 534 is operable to determine an actual oxygen concentration in the donor cylinders and / or non-donor cylinders of the engine during combustion. The actual oxygen concentration may be determined in any suitable manner. For example, an oxygen sensor located in the intake manifold may provide controller 534 with a sensor signal indicative of the actual oxygen concentration. As another example, the actual oxygen concentration may be derived from other operating parameters.

[0068] The controller 534 is operable to adjust a fuel injection amount of a donor cylinder to bring the actual oxygen concentration toward the planned oxygen concentration, and to adjust a fuel injection amount of a non-donor cylinder depending on the fuel injection adjustment of the donor cylinders and to maintain a further, second operating parameter. In one example, the controller 534 is operable to adjust a fuel injection amount of the non-donor cylinders with respect to a planned output torque provided by the donor cylinders and the non-donor cylinders. In another example, the controller 534 is operable to adjust a fuel injection amount of the non-donor cylinders to achieve or maintain a planned air-fuel ratio provided by the non-donor cylinders.In another example, controller 534 is operable to adjust the fuel injection amount of the non-donor cylinders based on a planned boost pressure. Because the turbine 518 of the turbocharger 520 is disposed in the exhaust pipe 514, which is in fluid communication with the non-donor cylinder group, the air-fuel ratio and boost pressure may be control targets for actively controlling the fuel injection amounts of the non-donor cylinders.

[0069] In some implementations, controller 534 is operable to enable differential fueling between the donor cylinders and the non-donor cylinders. The differential fueling represents a ratio representative of an amount of total fuel (comprising a first amount of the first fuel and a second amount of the second fuel) delivered to a single active donor cylinder and an amount of fuel delivered to a single non-donor cylinder. The differential fueling may be applied to a scheduled total fueling amount to determine how much of each fuel is delivered to the donor cylinders and the non-donor cylinders.Note that adjusting the differential fuel quantity may not change the total net fuel quantity; instead, it changes the distribution of the total fuel quantity between the donor and non-donor cylinders. As described with reference to the routine after . Fig. 6, the controller 534 is operable, for example, to adjust a differential total fuel injection amount between a donor cylinder total fuel injection amount and a non-donor cylinder total fuel injection amount in response to an indication of uncontrolled combustion. In particular, the controller 534 is operable to adjust an amount of the first fuel and / or the second fuel injected into each of a non-donor cylinder and a donor cylinder in response to an indication of uncontrolled combustion in a non-donor cylinder, while simultaneously adjusting an amount of the first fuel and the second fuel injected into a donor cylinder only in response to an indication of uncontrolled combustion in the donor cylinder.It will be appreciated that all fuel injection adjustments (to the donor and non-donor cylinders) are made to enable a net engine output torque to be maintained.

[0070] For example, in response to a first indication of uncontrolled combustion in a cylinder of the donor cylinder group, an injection quantity of the second fuel is increased in the affected donor cylinder and an injection quantity of the first fuel is decreased. At the same time, first and second fuel injection quantities are maintained in the non-donor cylinder group to maintain the output torque of the vehicle engine. In comparison, in response to a second indication of uncontrolled combustion in a cylinder of the non-donor cylinder group, an injection quantity of the first fuel in the affected donor cylinder is decreased while simultaneously maintaining an injection quantity of the second fuel in the affected donor cylinder.At the same time, an injection quantity of the first and / or second fuel is increased accordingly in a cylinder of the master cylinder group in order to maintain the output torque of the vehicle engine.

[0071] In this way, uncontrolled combustion in the affected cylinders is reduced by differentially adjusting the fuel quantities. In addition, by actively controlling the fuel injection quantities, the control device can control an EGR gas composition, which in turn also helps reduce uncontrolled combustion. The active fuel injection adjustment here allows the exhaust gas recirculation (EGR) to be varied without controlling an EGR flow rate through an EGR channel by changing an EGR valve position. In alternative embodiments, however, EGR rates can additionally or optionally be adjusted in response to the uncontrolled combustion by varying a position of the EGR valve. For example, in response to uncontrolled combustion in a cylinder of the non-donor cylinder group, the exhaust gas recirculation via an EGR channel and an EGR valve can be increased.

[0072] It will now Fig. 6, in which an exemplary routine 600 for adjusting a first and second fuel injection amount into a cylinder of the engine system of Fig. 5 in response to an indication of uncontrolled combustion. As shown therein, fuel injection adjustment may vary depending on whether the affected cylinder is a donor cylinder or a non-donor cylinder.

[0073] At 602, the routine includes a determination of whether there is an indication of uncontrolled combustion in a cylinder of the non-donor cylinder group. As described with reference to Fig.3, an indication of uncontrolled combustion as well as an identity of the affected cylinder(s) may be determined based on each of a combustion sensor output and a crankshaft speed sensor output. If uncontrolled combustion is confirmed in a first, non-donor cylinder, then the routine includes, at 604, decreasing an injection amount of the first (gaseous) fuel and maintaining an injection amount of the second (liquid) fuel in the cylinder of the first non-donor cylinder group while simultaneously increasing an injection amount of the first and / or second fuel in a cylinder of the second donor cylinder group to maintain the output torque of the vehicle engine. In response to the uncontrolled combustion in the non-donor cylinder, the fuel injection adjustments herein are made in both the donor cylinder and the non-donor cylinder.

[0074] If uncontrolled combustion in a cylinder of the non-donor cylinder group has not been confirmed, then at 606, uncontrolled combustion in a cylinder of the donor cylinder group may be confirmed based on each of the combustion sensor output and the crankshaft speed sensor output. Upon confirmation, in response to the indication of uncontrolled combustion in a second donor cylinder, at 608, the routine includes increasing an injection amount of the second fuel and decreasing an injection amount of the first fuel while maintaining an output torque of the vehicle engine. In response to the uncontrolled combustion in the non-donor cylinder, fuel injection adjustments herein are made only in the donor cylinder while maintaining the fuel injection amounts in the non-donor cylinder.

[0075] In this way, by increasing the amount of second fuel injected into an engine cylinder and / or reducing the amount of first fuel injected into the cylinder, uncontrolled cylinder combustion of a mixture of air and non-compression-ignitable fuel initiated by the combustion of a mixture of air and a compression-ignitable fuel can be reduced, and engine performance is improved. By temporarily reducing the consumption of the first gaseous fuel while allowing the engine to continue operating on at least some gaseous fuel, fuel efficiency benefits are achieved through the use of the gaseous fuel while simultaneously reducing uncontrolled combustion.

[0076] As used herein, an element or step referred to in the singular form and also preceded by the word "a" or "an" should not be considered to exclude multiple elements or steps unless such exclusion is explicitly stated. Furthermore, references to "one embodiment" of the present invention are not intended to exclude other embodiments also incorporating the recited features. Furthermore, unless explicitly stated to the contrary, embodiments that "comprise," "include," or "have" one or more elements with a particular property may include additional such elements that do not have that property. The terms "including" and "in which" are used as the plain language equivalents for the corresponding terms "comprising" and "wherein."Furthermore, the terms “first,” “second,” and “third,” etc., are used merely as labels and are not intended to imply any numerical requirements or a specific positional order with respect to their objects.

[0077] This written description uses examples to disclose the invention, including its best mode, and to enable one skilled in the art to practice the invention, including making and using all elements and systems and performing all incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that would be apparent to one skilled in the art. Such other examples are intended to be included within the scope of the invention if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

[1] Vehicle system comprising: a first vehicle which has: an engine system arranged in the vehicle and comprising an engine having a plurality of engine cylinders, each cylinder having at least one intake fuel injector and at least one direct fuel injector; at least one sensor connectable to a body of the engine to indicate cylinder combustion conditions; and a control system operable to determine an amount of a first gaseous fuel to be injected into the cylinders by the intake fuel injector and an amount of a second liquid fuel to be injected into the cylinders by the direct fuel injector based at least in part on the cylinder combustion conditions indicated by the at least one sensor; and a fuel storage vehicle connected to the first vehicle, wherein the fuel storage vehicle has a first fuel tank for storing the first gaseous fuel and the first vehicle has a second tank for storing the second liquid fuel, and wherein the vehicle system further comprises a fuel supply line connecting the first vehicle and the fuel storage vehicle for transferring the first gaseous fuel from the fuel storage vehicle to the first vehicle. [2] The vehicle system of claim 1, wherein the first fuel is compressed natural gas and the second fuel is diesel. [3] The vehicle system of claim 2, wherein the control system is further operable to vary the amount of first fuel injected into the at least one of the plurality of cylinders in response to the combustion conditions indicated by the at least one sensor, the variation comprising a decrease in the amount of first fuel injected by the intake fuel injectors. [4] A vehicle system according to claim 3, wherein the control system is further operable to, when the vehicle begins or is about to begin operating in a defined state, further varying the amount of first fuel injected into at least one of the plurality of cylinders in anticipation of uncontrolled cylinder combustion events; and when the defined condition ends, to resume the original fuel injection quantities. [5] The vehicle system of claim 2, wherein the control system is further operable to vary the amount of second fuel injected into the at least one of the plurality of cylinders in response to the combustion conditions indicated by the at least one sensor, the variation comprising increasing the amount of second fuel injected by the direct injectors. [6] The vehicle system of claim 5, wherein increasing the amount of the second fuel comprises retarding a fuel injection timing of the second fuel toward a power stroke.

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