FUEL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING MULTIPLE INJECTION SYSTEMS, AND METHOD FOR OPERATING MULTIPLE FUEL INJECTION SYSTEMS FOR AN INTERNAL COMBUSTION ENGINE

Abstract

A fuel system includes a first fuel rail. A first fuel delivery system including a plurality of first fuel injectors is connected to the first fuel rail. The plurality of first fuel injectors inject an amount of fuel into a first portion of an engine. A second fuel rail has a second fuel delivery system including a plurality of second fuel injectors. The plurality of second fuel injectors inject an amount of fuel into a second portion of the engine that is different from the first portion.A controller operatively connected to the first fuel delivery system and the second fuel delivery system selectively enables and disables operation of the first fuel delivery system and the second fuel delivery system based on either a detected temperature or a detected pressure of fuel passing to corresponding ones of the plurality of first fuel injectors and the plurality of second fuel injectors.

Description

INTRODUCTION

[0001] The present invention relates to the art of fuel control systems and, in particular, to a fuel system for an internal combustion engine having a plurality of injection systems and to a method for operating a plurality of fuel injection systems for an internal combustion engine.

[0002] For background information, reference is made at this point to the documents DE 10 2008 002 216 A1 and DE 10 2006 042 893 A1, which describe methods and systems for controlling fuel injection into the cylinders of an internal combustion engine.

[0003] Internal combustion engines contain a fuel system that combines a liquid fuel with air to form a combustible mixture. The combustible mixture is introduced into a cylinder, compressed, and ignited to form pressurized gases. The pressurized gases move a piston within the cylinder to generate energy to propel the vehicle. In some cases, the fuel system may include a carburetor that delivers fuel into a manifold to be combined with air. In other cases, the fuel system may include fuel injectors that create an atomized burst of an air-fuel mixture that is passed into the cylinder.

[0004] In some cases, the fuel injectors may be configured to deliver the atomized fuel into a manifold that leads into the cylinder. In other cases, the injector may deliver the fuel directly into the cylinder. In still other cases, the engine may include a first fuel delivery system including injectors that deliver fuel into the manifold and a second fuel delivery system including injectors that deliver fuel directly into the cylinder. One fuel system may operate during idle, and the other fuel system may operate when the vehicle is moving.

[0005] If the fuel system operating at idle is active for too long a period of time, engine temperatures and / or fuel pressures may exceed desired parameters. Increasing engine temperatures and / or fuel pressures may impair overall vehicle operating efficiency and may also place stress on certain engine components. Accordingly, it is desirable to provide a fuel system and method for controlling the operation of the first and second fuel delivery systems to maintain temperatures and / or fuel pressures within selected operating parameters.

[0006] The invention is therefore based on the task of fulfilling this wish. SUMMARY

[0007] This object is achieved with a fuel system having the features of claim 1 and with a method having the features of claim 7. Advantageous developments of the invention can be derived, inter alia, from the subclaims.

[0008] The fuel system includes a first fuel rail configured to be connected to a fuel source. A first fuel delivery system including a plurality of first fuel injectors is connected to the first fuel rail. The plurality of first fuel injectors is configured to inject an amount of fuel into a first portion of an internal combustion engine. A second fuel rail is configured to be connected to the fuel source. A second fuel delivery system including a plurality of second fuel injectors is connected to the second fuel rail. The plurality of second fuel injectors is configured to inject an amount of fuel into a second portion of the internal combustion engine that is different from the first portion.A controller is operatively connected to the first fuel delivery system and the second fuel delivery system. The controller is configured to selectively enable and disable operation of the first fuel delivery system and the second fuel delivery system based on either a detected temperature or a detected pressure of the fuel passing to corresponding ones of the plurality of first fuel injectors and the plurality of second fuel injectors.

[0009] In addition to one or more of the features described herein, the fuel system further includes a first pressure sensor and a first temperature sensor mounted in the first fuel rail, and a second temperature sensor and a second pressure sensor mounted in the second fuel rail.

[0010] In addition to one or more of the features described herein, the plurality of first fuel injectors are configured to inject fuel upstream of an intake valve of the internal combustion engine.

[0011] In addition to one or more of the features described herein, the plurality of second fuel injectors are configured to inject an amount of fuel directly into a cylinder of the internal combustion engine downstream of the intake valve.

[0012] In addition to one or more of the features described herein, the controller is configured to deactivate the second fuel delivery system during selected operating periods of the internal combustion engine.

[0013] In addition to one or more of the features described herein, the controller is configured to activate both the first fuel delivery system and the second fuel delivery system if one of the temperature sensed in the first fuel rail and the pressure sensed in the second fuel rail exceeds a selected value.

[0014] In another exemplary embodiment, a vehicle includes a body defining a passenger compartment. A plurality of wheels support the body. An internal combustion engine is supported within the body and is operatively connected to at least one of the plurality of wheels. The internal combustion engine includes a plurality of cylinders, an intake system including an intake manifold, and an intake valve selectively connecting the intake system to at least one of the plurality of cylinders. A fuel system is fluidly connected to the internal combustion engine and includes a first fuel rail configured to be connected to a fuel source. A first fuel delivery system including a plurality of first fuel injectors is connected to the first fuel rail.The plurality of first fuel injectors are configured to inject an amount of fuel into a first portion of the internal combustion engine. A second fuel rail is configured to be connected to the fuel source. A second fuel delivery system including a plurality of second fuel injectors is connected to the second fuel rail. The plurality of second fuel injectors are configured to inject an amount of fuel into a second portion of the internal combustion engine that is different from the first portion. A controller is operatively connected to the plurality of first fuel injectors and the plurality of second fuel injectors.The controller is configured to selectively enable and disable operation of selected ones of the plurality of first fuel injectors and the plurality of second fuel injectors based on either a detected temperature or a detected pressure of the fuel passing to corresponding ones of the first fuel rail and the second fuel rail.

[0015] In addition to one or more of the vehicle features described herein, the fuel system further includes a first pressure sensor and a first temperature sensor mounted in the first fuel rail, and a second temperature sensor and a second pressure sensor mounted in the second fuel rail.

[0016] In addition to one or more of the vehicle features described herein, the plurality of first fuel injectors are configured to inject fuel into the intake manifold of the intake valve.

[0017] In addition to one or more of the vehicle features described herein, the plurality of second fuel injectors are configured to inject an amount of fuel directly into each of the plurality of cylinders.

[0018] In addition to one or more of the vehicle features described herein, the controller is configured to deactivate the second fuel delivery system during selected periods of engine operation.

[0019] In addition to one or more of the vehicle features described herein, the controller is configured to activate both the first fuel delivery system and the second fuel delivery system if one of the temperature sensed in the first fuel rail and the pressure sensed in the second fuel rail exceeds a selected value.

[0020] The inventive method for operating a plurality of fuel injection systems for an internal combustion engine carried in a vehicle comprises injecting fuel into a first portion of the internal combustion engine by a plurality of first fuel injectors and injecting fuel into a second portion of the internal combustion engine, which is different from the first portion, by a plurality of second fuel injectors. The method further comprises detecting an operating mode of the vehicle, deactivating the plurality of first fuel injectors based on the operating mode of the vehicle, detecting a temperature and a pressure of the fuel at the plurality of first fuel injectors, and activating the plurality of first fuel injectors if the temperature and pressure are different.one of the temperature and pressure of the fuel exceeds a selected threshold.

[0021] In addition to one or more of the steps described herein, activating the plurality of first fuel injectors includes detecting that the temperature of the fuel at each of the plurality of first fuel injectors exceeds a selected temperature threshold.

[0022] In addition to one or more of the steps described herein, activating a fuel pump to deliver fuel to the plurality of first fuel injectors when the temperature of the fuel at each of the plurality of first fuel injectors exceeds the selected temperature threshold to support at least 10 injections of fuel.

[0023] In addition to one or more of the steps described herein, activating the plurality of first fuel injectors includes detecting that the pressure of the fuel at each of the plurality of first fuel injectors exceeds a selected pressure threshold.

[0024] In addition to one or more of the steps described herein, activating the plurality of first fuel injectors when the pressure of fuel at the plurality of first fuel injectors exceeds the selected pressure threshold includes delivering fuel to the internal combustion engine without activating a fuel pump.

[0025] In addition to one or more of the steps described herein, activating the plurality of first fuel injectors when the pressure of fuel at the plurality of first fuel injectors exceeds the selected pressure threshold, delivering fuel to the engine without activating the fuel pump, includes delivering no more than 3 injections of fuel to the engine.

[0026] In addition to one or more of the steps described herein, the method further includes determining that the one of the temperature and pressure of the fuel at the plurality of first fuel injectors has fallen below the selected threshold, and deactivating the plurality of first fuel injectors.

[0027] In addition to one or more of the steps described herein, the method further includes detecting the operating mode of the vehicle prior to deactivating the plurality of first fuel injectors and deactivating the plurality of first fuel injectors if the operating mode indicates that the vehicle is idling.

[0028] The above-described features and advantages and other features and advantages of the invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 is a left side view of a vehicle including an internal combustion engine and a fuel control system, according to one example; Fig. 2 a partial sectional view of the internal combustion engine of Fig. 1 including a fuel system having multiple injection systems, according to one example; Fig. 3 is a schematic view of the fuel control system of the internal combustion engine of Fig. 2 according to an example, and Fig. 4 is a flow chart illustrating a method for controlling fuel delivery by the fuel system of Fig. 3, according to a non-limiting example. DETAILED DESCRIPTION

[0030] A vehicle according to an example is at 10 in Fig. 1. The vehicle 10 includes a body 12 supported on a plurality of wheels 16. The body 12 partially defines a passenger compartment 20 having seats 23 positioned behind an instrument panel 26. The vehicle 10 includes an internal combustion engine (ICE) 34 that provides power to one or more of the plurality of wheels 16.

[0031] With reference to Fig. 2, an ICE engine 34 includes an engine block 40 containing a plurality of cylinders, one of which is indicated at 42. The engine block 40 supports a crankshaft 44, which in turn supports a connecting rod 46 connected to a piston 48. As the crankshaft 44 rotates, the piston 48 reciprocates within the cylinder 42. A cylinder head 54, including an intake system 56, is connected to the engine block 40. The cylinder head 54 supports a first camshaft 58a and a second camshaft 58b that rotate to open an intake valve 60 and an exhaust valve 62. Springs (not separately labeled) associated with the intake valve 60 and the exhaust valve 62 provide closing force to the valves.

[0032] The ICE engine 34 includes a combustion chamber 64 defined between the piston 48 and the cylinder head 54. A spark plug 66 disposed in the cylinder head 54 selectively ignites a combustible mixture to move a piston 48. In some cases, the combustible mixture is formed in an intake manifold 70 of an intake system 56 and passed into the combustion chamber 64 via the intake valve 60. Exhausted gases formed after combustion are directed from the combustion chamber 64 through the exhaust valve 62 as exhaust gases 63. In other cases, the combustible mixture is introduced directly into the combustion chamber 64. In each case, a fuel system 80 generates the combustible mixture by delivering atomized fuel sprays 83 and 84 into the ICE 34.

[0033] Now, in describing a fuel system 80 according to an example with continued reference to Fig. 2 Reference to Fig. 3. The fuel system 80 includes a first fuel delivery system 82 defined by a plurality of first fuel injectors 84 and a second fuel delivery system 86 defined by a plurality of second fuel injectors 88. The plurality of first and second fuel injectors 84 and 88 are configured to deliver a fuel to various portions of an ICE engine 34, as more fully described in detail herein. In one example, the plurality of first fuel injectors 84 are mounted on the intake system 56 upstream of an intake valve 60, and the plurality of second fuel injectors 88 are mounted on the cylinder head 54 and positioned to deliver a quantity of fuel directly into the combustion chamber 64.

[0034] In one example, a plurality of first fuel injectors 84 are connected to a first fuel rail 90, and a plurality of second fuel injectors 88 are connected to a second fuel rail 92. The first fuel rail 90 includes a first inlet 94 and a second inlet 96, and the second fuel rail 92 includes a third inlet 97. It should be understood that the number and location of inlets, as well as the specific location of a first fuel rail 90 and a second fuel rail 92, may vary. Regardless of the configuration, the first fuel rail 90 and the second fuel rail 92 are fluidly connected to a source 99 of fuel 100.

[0035] A fuel pump 104 is fluidly connected between the fuel source 100 and first and second fuel rails 90 and 92. The fuel pump 104 delivers a pressurized fuel flow to each fuel rail 90, 92 to be injected into the combustion chamber 64 by a plurality of first fuel injectors 84 and / or a plurality of second fuel injectors 86, as needed. In one example, a first temperature sensor 108 is disposed in the first fuel rail 90 and a second temperature sensor 110 is disposed in the second fuel rail 92. Additionally, a first pressure sensor 114 is disposed in the first fuel rail 90 and a second pressure sensor 116 is disposed in the second fuel rail 92.

[0036] First and second temperature sensors 108 / 110 and first and second pressure sensors 114 / 116 provide feedback to a fuel control system 120 for injecting fuel from the plurality of first fuel injectors 84 and / or the plurality of second fuel injectors 88. The fuel control system 120 includes a controller having a central processing unit (CPU) 122, a non-volatile memory 124, a temperature evaluation module 126, and a pressure evaluation module 128. While shown as co-located, components of the controller 120 may be located in various areas of the vehicle 10. Further, while shown as separate modules, the temperature evaluation module 126 and the pressure evaluation module 128 may be located in a single combined temperature / pressure evaluation module.

[0037] Now, in describing a method 200 for controlling fuel delivery by the plurality of first fuel injectors 84 and the plurality of second fuel injectors 86 into the combustion chamber 64, reference will be made to Fig. 4. The method 200 is initiated in block 210. At this point, a determination is made as to whether both the plurality of first fuel injectors 84 and the plurality of second fuel injectors 88 are active in block 212. In one example, the controller 120 may determine an operating mode of the vehicle 10. In one example, during idle periods, the plurality of first fuel injectors 84 may be active and the plurality of second fuel injectors 88 may not be active. Therefore, fuel is delivered into the combustion chamber 64 only through the intake valve 60.

[0038] If both the plurality of first fuel injectors 84 and the plurality of second fuel injectors 88 are active, the method 200 ends in block 214. If only one of the plurality of first fuel injectors 84 and the plurality of second fuel injectors 88 is active, e.g., during idle, the temperature evaluation module 126 reads a second temperature sensor 110 to determine the temperature in the second fuel rail 92 in block 220. The sensed temperature is compared to a temperature threshold stored in a non-volatile memory 124. If the temperature in the second fuel rail 92 is within a specified temperature limit, the method 200 transitions to block 222.

[0039] In block 222, the pressure evaluation module 128 reads a second pressure sensor 116 to determine the fuel pressure in the second fuel rail 92. The sensed pressure is compared to a pressure threshold stored in non-volatile memory 124. If the fuel pressure in the second fuel rail 92 is within a specified pressure limit, the method 200 transitions to block 214 and ends. The method 200 may be repeated continuously or at selected intervals depending on the operating mode of the vehicle 10, operating temperatures, and the ambient temperature. For example, the method 200 may be repeated more frequently during idle in a hot climate and less frequently during highway driving in a cold climate.

[0040] In one example, if the temperature sensed at block 220 is higher than predetermined temperature limits stored in non-volatile memory 124, method 200 proceeds to block 230 to reactivate the plurality of second fuel injectors 88. Controller 120 may activate fuel pump 104 to enable ten (10) or more injections of fuel by the plurality of second fuel injectors 88 to reduce temperatures in second fuel rail 92. Temperature evaluation module 126 samples second temperature sensor 110 again to determine the effect the injection had on the fuel temperature in second fuel rail 92 at block 240. If the fuel temperature has dropped below predetermined limits, method 200 proceeds to block 214 and ends.If, on the other hand, the fuel temperature remains elevated, method 200 returns to block 230. At this point, fuel pump 104 is reactivated and the plurality of second fuel injectors are reactivated to enable additional fuel injection events. This control loop is repeated until the fuel temperature in second fuel rail 92 is within predetermined limits.

[0041] In one example, if the temperature sensed in block 220 is within the predetermined temperature limits stored in non-volatile memory 124, but the pressure evaluation module 128 determines that the pressure sensed in block 222 is outside predetermined pressure limits stored in non-volatile memory 124, the method 200 transitions to block 230 to reactivate the plurality of second fuel injectors 88. In this case, the controller 120 may only activate the plurality of second fuel injectors 88 to enable one or two (1 or 2) injections of fuel. Therefore, if the sensed pressure is outside stored pressure limits, the fuel pump 104 may not need to be activated to reduce the pressure in the second fuel rail 92.

[0042] The pressure evaluation module 128 samples the second temperature sensor 110 again to determine what effect the injection had on the fuel pressure in the second fuel rail 92. If the fuel pressure has fallen below predetermined limits, the method 200 proceeds to block 214 and ends. On the other hand, if the fuel pressure remains elevated, the method 200 returns to block 230. The plurality of second fuel injectors are reactivated to enable additional fuel injection events. This control loop is repeated until the fuel pressure in the second fuel rail 92 is within predetermined limits.

[0043] At this point, it should be understood that the examples described herein provide a system for controlling an internal combustion engine having multiple fuel injection systems to mitigate pressure and temperature parameters in fuel supply rails. Maintaining temperature and pressure within predetermined limits protects pressure relief components. That is, when the temperature and pressure of fuel in the one or more fuel rails are within limits, a pressure relief valve does not need to be activated. Reducing the number of activations of the pressure relief valve increases overall component life. Further, while described with respect to deactivating the plurality of second fuel injectors, e.g., direct injection injectors, the method may also control the operation of indirect injection events. legend

[0044] In the drawings, N stands for No and Y stands for Yes.

Claims

[1] Fuel system (80) comprising: a first fuel rail (90) configured to be connected to a fuel source (100); a first fuel delivery system (82) including a plurality of first fuel injectors (84) connected to the first fuel rail (90), the plurality of first fuel injectors (84) configured to inject a quantity of fuel into a first portion of an internal combustion engine (34); a second fuel rail (92) configured to be connected to the fuel source (100); a second fuel delivery system (86) including a plurality of second fuel injectors (88) connected to the second fuel rail (92), the plurality of second fuel injectors (88) configured to inject an amount of fuel into a second portion of the internal combustion engine (34) that is different from the first portion; and a controller (120) operatively connected to the first fuel delivery system (82) and the second fuel delivery system (86), the controller (120) configured to selectively enable and disable operation of the first fuel delivery system (82) and the second fuel delivery system (86) based on either a detected temperature or a detected pressure of the fuel passing to corresponding ones of the plurality of first fuel injectors (84) and the plurality of second fuel injectors (88). [2] The fuel system (80) of claim 1, further comprising a first pressure sensor (114) and a first temperature sensor (108) mounted in the first fuel rail (90), and a second pressure sensor (116) and a second temperature sensor (110) mounted in the second fuel rail (92). [3] The fuel system (80) of claim 2, wherein the plurality of first fuel injectors (84) are configured to inject fuel upstream of an intake valve of the internal combustion engine (34). [4] The fuel system (80) of claim 3, wherein the plurality of second fuel injectors (88) are configured to inject a quantity of fuel directly into a cylinder (42) of the internal combustion engine (34) downstream of the intake valve. [5] The fuel system (80) of claim 4, wherein the controller (120) is configured to deactivate the second fuel delivery system (86) during selected operating periods of the internal combustion engine (34). [6] The fuel system (80) of claim 5, wherein the controller (120) is configured to activate both the first fuel delivery system (82) and the second fuel delivery system (86) if the detected temperature in the first fuel rail (90) or the detected pressure in the second fuel rail (92) exceeds a selected value. [7] A method of operating a plurality of fuel injection systems for an internal combustion engine (34) carried in a vehicle (10), the method comprising: Injecting fuel into a first portion of the internal combustion engine (34) by a plurality of first fuel injectors (84); Injecting fuel into a second portion of the internal combustion engine (34) different from the first portion by a plurality of second fuel injectors (88); Detecting an operating mode of the vehicle (10); Deactivating the plurality of first fuel injectors (84) based on the operating mode of the vehicle (10); Detecting a temperature or a pressure of the fuel at the plurality of first fuel injectors (84), and Activating the plurality of first fuel injectors (84) if the temperature or pressure of the fuel exceeds a selected threshold. [8] The method of claim 7, wherein activating the plurality of first fuel injectors (84) comprises detecting that the temperature of the fuel at each of the plurality of first fuel injectors (84) exceeds a selected temperature threshold. [9] The method of claim 7, wherein activating the plurality of first fuel injectors (84) comprises detecting that the pressure of the fuel at each of the plurality of first fuel injectors (84) exceeds a selected pressure threshold. [10] The method of claim 9, wherein activating the plurality of first fuel injectors (84) when the pressure of the fuel at the plurality of first fuel injectors (84) exceeds the selected pressure threshold comprises delivering fuel to the internal combustion engine (34) without activating a fuel pump (104).

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