Patent Publication Number: US-2004050345-A1

Title: Fuel reformer control system and method

Description:
FIELD OF THE DISCLOSURE  
       [0001] The present disclosure relates to generally to a control system, and more particularly to a control system for a fuel reformer.  
       BACKGROUND OF THE DISCLOSURE  
       [0002] Fuel reformers reform hydrocarbon fuel into a reformate gas such as hydrogen-rich gas. Such reformate gas may be utilized as fuel or fuel additive in the operation of an internal combustion engine. Such reformate gas may also be utilized to regenerate an emission abatement device or as a fuel for a fuel cell.  
       SUMMARY OF THE DISCLOSURE  
       [0003] According to one aspect of the present disclosure, there is provided an electronic control unit for controlling operation of both an internal combustion engine and a fuel reformer.  
       [0004] In one specific implementation, the electronic control unit is embodied as an engine control unit of a vehicle or a stationary power generator. As such, the engine control unit executes a routine for controlling operation of the internal combustion engine, along with a routine for controlling operation of the fuel reformer. Such routines may be embodied as separate software routines, or may be combined as a single software routine.  
       [0005] In accordance with another aspect of the present disclosure, there is provided a method for operating a power system having an internal combustion engine and a fuel reformer by use of the same control unit.  
       [0006] In one specific implementation of this method, the control unit is the engine control unit of a vehicle or stationary power generator.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is a simplified block diagram of a power system having a fuel reformer and an internal combustion under the control of a common controller;  
     [0008]FIG. 2 is a simplified block diagram of a power system in which the reformate gas produced by the fuel reformer is supplied to the intake of an internal combustion engine; and  
     [0009]FIG. 3 is a simplified block diagram similar to FIG. 2, but showing a power system in which the reformate gas produced by the fuel reformer is supplied to an emissions abatement device. 
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS  
     [0010] While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives following within the spirit and scope of the invention as defined by the appended claims.  
     [0011] Referring now to FIG. 1, there is shown a power system  10  having an internal combustion engine  12  and fuel reformer  14 . The internal combustion engine  12  may be embodied as any type of internal combustion engine including, for example, a spark-ignited gasoline engine, a diesel engine, a natural gas engine, or the like. In such a way, the internal combustion engine  12  produces mechanical output which is utilized to drive or otherwise mechanically power a driven mechanism (not shown) such as a transmission, specifically a vehicle transmission, which is utilized to propel a vehicle or a power generator or the like for producing electrical power.  
     [0012] The fuel reformer  14  reforms (i.e., converts) hydrocarbon fuels into a reformate gas that includes, amongst other things, hydrogen gas. The fuel reformer  14  may be embodied as any type of a fuel reformer such as, for example, a catalytic fuel reformer, a thermal fuel reformer, a steam fuel reformer, or any other type of partial oxidation fuel reformer. The fuel reformer  14  may also be embodied as a plasma fuel reformer (known generally as a “plasmatron”). A plasma fuel reformer uses plasma to convert hydrocarbon fuel into a reformate gas which is rich in, amongst other things, hydrogen gas and carbon monoxide. Systems including plasma fuel reformers are disclosed in U.S. Pat. No. 5,425,332 issued to Rabinovich et al.; U.S. Pat. No. 5,437,250 issued to Rabinovich et al.; U.S. Pat. No. 5,409,784 issued to Bromberg et al.; and U.S. Pat. No. 5,887,554 issued to Cohn, et al., the disclosures of each of which is hereby incorporated by reference.  
     [0013] Both the engine  12  and the fuel reformer  14  are under the control of a common controller. In particular, the internal combustion engine  12  is electrically coupled to an electronic control unit  16  via a signal line  18 , whereas the fuel reformer  14  is electrically coupled to the electronic control unit  16  via a signal line  20 . In such a way, the electronic control unit  16  may be programmed or otherwise configured to control the operation of both the engine  12  and the fuel reformer  14 . Such a feature eliminates the need to provide separate controllers for the engine  12  and the fuel reformer  14  thereby lowering costs and complexity associated with the design of the power system  10 .  
     [0014] Referring now to FIGS. 2 and 3, there are shown specific exemplary implementations of the power system  10 . In the embodiment shown in FIG. 2, the output from the fuel reformer  14  (i.e., reformate gas) is supplied to the intake of the engine  12 , whereas in the embodiment shown in FIG. 3, the output from the fuel reformer  14  (i.e., reformate gas) is supplied to an emission abatement device  24  such as a NOx absorber or a soot filter.  
     [0015] Moreover, in the embodiments shown in FIGS. 2 and 3, the electronic control unit  16  is embodied as an engine control unit  26 . In particular, engine systems, such as vehicle systems or systems for use in the design of a stationary power generator, include an engine control unit which is, in essence, the master computer responsible for interpreting electrical signals sent by engine sensors and for activating electronically-controlled engine components to control the engine. For example, an engine control unit is operable to, amongst many other things, determine the beginning and end of each injection cycle of each engine cylinder, or determine both fuel metering and injection timing in response to sensed parameters such as engine crankshaft position and rpm, engine coolant and intake air temperature, and absolute intake air boost pressure.  
     [0016] As will herein be described in greater detail, in addition to controlling operation of the engine  12 , the engine control unit  26  of the present disclosure also controls operation of the fuel reformer  14 . In such a way, the engine control unit  26  is also, in essence, the master computer responsible for interpreting electrical signals sent by sensors associated with the fuel reformer (or engine) and for activating electronically-controlled components associated with the fuel reformer in order to control the fuel reformer. For example, the engine control unit  26  of the present disclosure is operable to, amongst many other things, determine the beginning and end of each injection cycle of fuel into the fuel reformer, determine the amount and ratio of fuel and air to be introduced into the fuel reformer, determine the power level to supply to the fuel reformer in response to sensed parameters such as chemical composition of the reformate gas being produced by the fuel reformer, engine rpm, temperature of the fuel reformer or gas exiting therefrom, and oxygen content of the reformate gas.  
     [0017] To do so, the engine control unit  26  includes a number of electronic components commonly associated with electronic units which are utilized in the control of engine systems. For example, the engine control unit  26  may include, amongst other components customarily included in such devices, a processor such as a microprocessor  28  and a memory device  30  such as a programmable read-only memory device (“PROM”) including erasable PROM&#39;s (EPROM&#39;s or EEPROM&#39;s).  
     [0018] The memory device  30  is provided to store, amongst other things, instructions in the form of, for example, a software routine (or routines) which, when executed by the processing unit, allows the engine control unit  26  to control operation of both the engine  12  and the fuel reformer  14 . To do so, as shown in FIGS. 2 and 3, the engine control unit  26  is electrically coupled to both the engine  12  and the fuel reformer  14 . In particular, the engine control unit  26  is electrically coupled to the engine  12  via the signal line  18 , whereas the engine control unit  26  is electrically coupled to the fuel reformer  14  via the signal line  20 . Although each is shown schematically as a single line, it should be appreciated that the signal lines  18 ,  20  may be configured as any type of signal carrying assembly which allows for the transmission of electrical signals in either one or both directions between the engine control unit  26  and the engine  12  or the fuel reformer  14 , respectively. For example, either one or both of the signal lines  18 ,  20  may be embodied as a wiring harness having a number of signal lines which transmit electrical signals between the engine control unit  26  and the engine  12  or the fuel reformer  14 , respectively. In such an arrangement, signals generated by operation of a number of engine sensors  34  or fuel reformer sensors  36  are transmitted to the engine control unit  26  via the corresponding wiring harness, and signals generated by the engine control unit  26  are transmitted to the engine  12  or the fuel reformer  14  by the corresponding wiring harness. It should be appreciated that any number of other wiring configurations may be used. For example, individual signal wires may be used, or a system utilizing a signal multiplexer may be used for the design of either one or both of the signal lines  18 ,  20 . Moreover, the signal lines  18 ,  20  may be integrated such that a single harness or system is utilized to electrically couple both the engine  12  and the fuel reformer  14  to the engine control unit  26 .  
     [0019] The engine control unit  26  also includes an analog interface circuit  32 . The analog interface circuit  32  converts the output signals from the various analog engine sensors  34  and fuel reformer sensors  36  into a signal which is suitable for presentation to an input of the microprocessor  28 . In particular, the analog interface circuit  32 , by use of an analog-to-digital (A/D) converter (not shown) or the like, converts the analog signals generated by the sensors  34 ,  36  into a digital signal for use by the microprocessor  28 . It should be appreciated that the A/D converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  28 . It should also be appreciated that if any one or more of the sensors  34 ,  36  generate a digital output signal, the analog interface circuit  32  may be bypassed.  
     [0020] Similarly, the analog interface circuit  32  converts signals from the microprocessor  28  into an output signal which is suitable for presentation to the electrically-controlled components  44  associated with the engine  12  and the electronically-controlled components  46  associated with the fuel reformer  14 . In particular, the analog interface circuit  32 , by use of a digital-to-analog (D/A) converter (not shown) or the like, converts the digital signals generated by the microprocessor  28  into analog signals for use by the electronically-controlled components  44  associated with the engine such as the fuel injector assembly, ignition assembly, fan assembly, etcetera, along with analog signals for use by electronically-controlled components  46  associated with the fuel reformer  14  such as, depending on the type and/or design of the fuel reformer, the air and/or fuel metering valves, fuel injector, plasma head, etcetera. It should be appreciated that, similar to the A/D converter described above, the D/A converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  28 . It should also be appreciated that if any one or more of the electronically-controlled components  44  associated with the engine  12  or electronically-controlled components  46  associated with the fuel reformer  14  operate on a digital input signal, the analog interface circuit  32  may be bypassed.  
     [0021] Hence, the engine control unit  26  may be operated to control operation of both the engine  12  and the fuel reformer  14 . In particular, the engine control unit  26  operates in a closed-loop control scheme in which the engine control unit  26  monitors outputs of the sensors  34 ,  36  in order to control the inputs to the controlled components  44 ,  46  thereby managing the operation of both the engine  12  and the fuel reformer  14 . In particular, the electronic control unit  26  communicates with the sensors  34  in order to determine, amongst numerous other things, the engine coolant temperature, manifold air pressure, crankshaft/flywheel position and speed, and the amount of oxygen in the exhaust gas. Armed with this data, the electronic control unit  26  performs numerous calculations each second, including looking up values in preprogrammed tables, in order to execute routines to perform such functions as varying spark timing or determining how long the fuel injector is to be left open in a particular cylinder.  
     [0022] Contemporaneous with such control of the engine  12 , the engine control unit  26  also executes a routine for controlling operation of the fuel reformer  14 . In particular, the electronic control unit  26  communicates with the sensors  36  in order to determine, amongst numerous other things, the amount of air or fuel being supplied to the fuel reformer, the amount of oxygen in the reformate gas, the temperature of the fuel reformer or the reformate gas, and the composition of the reformate gas. Armed with this data, the electronic control unit  26  performs numerous calculations each second, including looking up values in preprogrammed tables, in order to execute algorithms to perform such functions as determining when or how long the fuel reformer&#39;s fuel injector or other fuel input device is opened, controlling the power level input to the fuel reformer, controlling the amount of air advanced through an inlet air valve of the fuel reformer, etcetera.  
     [0023] In operation, the engine control unit  26  controls operation of both the engine  12  and the fuel reformer  14 . In particular, during operation of the engine  12 , the engine control unit  26  executes a fuel injector control routine which, amongst other things, generates a number of injection signals in the form of injection pulses which are communicated to the individual injectors of the engine&#39;s fuel injector assembly. In response to receipt of the injection pulse, a fuel injector is opened for a predetermined period of time, thereby injecting fuel into the corresponding cylinder of the engine  12 . Contemporaneous with execution of the engine control routine, the engine control unit  26  executes a fuel reformer control routine which, amongst other things, generates a number of control signals which are communicated to the various electronically-controlled components  46  associated with the fuel reformer  14 , thereby controlling operation of the reformer  14 . For example, signals are generated and communicated for, amongst other things, varying the amount of air being supplied to the fuel reformer through the reformer&#39;s air inlet valve, varying the power supplied to the plasma fuel reformer, or operating the fuel injector so as to inject fuel, or a certain amount of fuel, into the fuel reformer.  
     [0024] Moreover, the engine control unit  26  also monitors input from the various sensors  36  associated with the reformer  14  in order to utilize such input in the closed-loop control of the reformer  14 . For example, signals communicated to the engine control unit  26  are utilized to monitor chemical composition of a reformate gas produced by the fuel reformer, the temperature of the reformer or the reformate gas exiting therefrom, or the oxygen content of the reformate gas.  
     [0025] It should be appreciated that such routines (i.e., the fuel injector control routine and the fuel reformer control routine) may be embodied as separate software routines, or may be combined as a single software routine.  
     [0026] As can be seen from the foregoing description, the concepts of the present disclosure provide numerous advantages and benefits relative to other systems. For example, amongst other things, the concepts of the present disclosure allow for the control of both an internal combustion engine and a fuel reformer with the same electronic control unit (e.g., the engine control unit  26 ). As a result, the costs and complexity of the power system is reduced relative to systems requiring separate control units.  
     [0027] While the concepts of the present disclosure have been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.  
     [0028] There are a plurality of advantages of the concepts of the present disclosure arising from the various features of the systems described herein. It will be noted that alternative embodiments of each of the systems of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of a system that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the invention as defined by the appended claims.