Abstract:
A diesel engine coupled to a transmission and having a fuel injector control system which among other things monitors the load on the engine by measuring the transmission line pressure, a higher pressure being indicative of a greater load. When the pressure is below a preset value and the engine is sufficiently warm, the normal injector firing sequence is altered by not actuating injectors at spaced intervals in the firing sequence. As the pressure and therefore the load decreases, the intervals between which injectors are not actuated are decreased so that in a given number of engine rotations there are fewer injector actuations and as a result of corresponding cylinders being idle, less fuel is supplied to the engine at lighter loads.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/864,908 filed Nov. 8, 2006, the entirety of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of diesel engines and in particular to a system and method of improving the fuel economy of a diesel engine. 
     BACKGROUND OF THE INVENTION 
     Diesel engines may have different firing orders depending on the make and model of the engine. Firing order in a diesel engine can be described by sequentially naming the injectors in the order they fire, rather than describing the injector by its location on the engine. For example, in an eight injector engine the firing order may be 12345678 even if the injectors are not physically arranged in such order. Firing order may alternatively be designated according to location of the injector being fired. For example, in an engine that has eight injectors, the firing order may be designated 13246587, identifying the first injector as firing first, the third injector as firing second, the second injector as firing third, and so on. 
     It is known to turn off an injector in a non diesel engine in order to conserve fuel. However, currently, if a diesel engine has a single injector that is not firing the engine will shake. Thus there is a need for an invention that eliminates the shake in a diesel engine when an injector is turned off. 
     SUMMARY OF THE INVENTION 
     In one aspect a system is provided that operates to turn off, or not fire, injectors in a diesel engine based on conditions in the engine. In one aspect the firing “outage” is spread equally among all cylinders to eliminate shake. In one embodiment such a system includes a control module programmed to receive information from the engine and based on the information received control the firing of injectors in the engine, specifically, to turn off certain of the injectors based on the information received. As will be apparent to one skilled in the art a control module may simply be the existing device in a vehicle that controls firing of injectors that is specifically programmed in accordance with the present invention. Information that may be used by the control module includes line pressure in the transmission. 
     In another aspect of the invention a method of controlling the firing of injectors in a diesel engine is provided which includes the steps of detecting conditions in a diesel engine and using means such as logic or programming to instruct a firing sequence in the injectors of the diesel engine. In one embodiment such instructions include turning off at least one such injector. These and other aspects of the invention will be apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a diagram showing portions of a fuel and transmission system of a diesel engine illustrating an embodiment of the invention operable in accordance with at least one aspect of the invention. 
         FIG. 2  is a flow chart illustrating a method in accordance with an embodiment of the present invention. 
         FIG. 3  is a flow chart illustrating a method in accordance with an embodiment of the present invention. 
         FIG. 4  is a flow chart illustrating a method in accordance with an embodiment of the present invention. 
         FIG. 5  depicts a table indicating fuel savings based on the nonfiring of given injectors and an example of a firing sequence in accordance with an embodiment of the present invention. 
         FIG. 6  depicts an example of a firing sequence in accordance with an embodiment of the present invention. 
         FIG. 7  depicts an example of a firing sequence in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, for purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one having ordinary skill in the art that the invention may be practiced without these specific details. In some instances, well-known features may be omitted or simplified so as not to obscure the present invention. Furthermore, reference in the specification to phrases such as “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of phrases such as “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     In accordance with the present invention, a system is provided that turns off selected injectors at given diesel engine conditions to provide enhanced fuel economy. Now referring to  FIG. 1 , in one aspect, a system is depicted that operates to turn off, or not fire, injectors in a diesel engine based on conditions in the engine. A system  2  according to the invention includes engine  10 , a fuel system including a fuel tank  12 , a fuel pump  14 , fuel filter  16 , fuel line  17  and a fuel rail  18  that delivers fuel to injectors  20  for delivering fuel to the engine cylinders or intake ports, transmission  30 , sensor(s)  40  and control module  50 . 
     Each injector  20  includes a valve  22  such as but not limited to a solenoid valve, disposed at the inlet of the injector  20 . In one embodiment fuel rail  18  includes a bypass outlet  19  which delivers fuel to a fuel return line  26  leading to the fuel tank  12 . Each valve  22  is normally open but is closable (see closed valve  22   c ) to cut off fuel flow to a particular injector  20 . 
     Injectors  20  may be any injector known in the art such as but not limited to magnetic injectors. 
     In one aspect the firing “outage” is spread equally among all cylinders to eliminate shake. In one embodiment such a system includes a control module programmed to receive information from the engine and based on the information received control the firing of injectors in the engine, specifically, to turn off certain of the injectors based on the information received. As will be apparent to one skilled in the art a control module may simply be the existing device in a vehicle that controls firing of injectors that is specifically programmed in accordance with the present invention. Information that may be used by the control module includes line pressure in the transmission. 
     Control of the firing of the injectors may be by any suitable means. In an automotive engine, an electronic control unit (ECU) or engine control module (ECM) may be used to initiate the setting although a suitable passive system might alternatively be applied, depending upon the engine control system capabilities. If desired, any other suitable control system for varying firing of the injectors may be utilized. Such alternatives would include a regulator with a variable control actuated by any suitable electronic or pressure responsive means. 
     A control signal may be a pulse width modulated signal to engage, partially engage, and disengage, a valve based on engine, vehicle, and/or transmission operating conditions. 
     Control module  50  may be a conventional microcomputer, including a microprocessor unit  52 , input/output ports  54 , an electronic storage medium for executable programs and calibration values shown as read only memory chip  56 , in this particular example, random access memory  58 , keep alive memory  60  and a conventional data bus. Control module  50  is adapted to receive various signals from sensors  40  coupled to engine  10 , including measurement of inducted mass air flow (MAF); engine coolant temperature (ECT); a profile ignition pickup signal (PIP); throttle position (TP); absolute Manifold Pressure Signal (MAP); engine speed signal (RPM); transmission pressure and the like as are well known in the art. The control module may alternatively be a computer such as a laptop that is adapted to be plugged into the diagnostic port of an engine, containing software adapted to monitor and process the signals received from the engine. Alternatively, an after-market product similar to the Juice ECM Module available from Edge Products of Ogden, Utah may be employed as a control module. 
     In one embodiment, the transmission pressure is measured by a pressure sensor  40  and the sensed pressure is transmitted to an engine control which in turn operates a valve actuator to close a selected valve  22  whenever the transmission line pressure reaches a predetermined level. If desired, the valves  22  could be provided with a pressure-responsive actuator that could utilize pressure in the intake manifold or differential pressures in the intake system to close the valve  22  whenever a desired pressure level is reached. 
     In operation a solenoid valve actuator may be de-energized during engine starting and normal operation up to a predetermined level such as transmission pressure, engine temperature or the like. 
     In another embodiment, valve  22  may be a magnetic solenoid valve. 
     In one embodiment, when the transmission pressure rises to one or more predetermined levels, the valve actuator is energized to close a selected valve  22 , cutting off the flow of fuel through injector  20 . The resulting increased fuel pressure may be relieved by excess fuel being delivered through the fuel return line  26  to the fuel tank  12 . With the changing of the fuel pressure, the control module  50  may adjust a pulse width control for the injectors  20  to maintain the desired engine output as is well known in the art. It is contemplated that increased pressure may be desirable, so that the injectors  20  inject a greater amount of fuel for a pulse width of a similar time period so that, at any specified control pulse width, the amount of fuel injected by each injector is increased and the engine output is thereby increased. 
     When the transmission pressure is reduced, the valve actuator may be energized, closing valve  22  and stopping fuel flow through the injector  20 . 
     In another aspect of the invention a method of controlling the firing of injectors in a diesel engine is provided which includes the steps of detecting conditions in a diesel engine and using means such as logic or programming to instruct a firing sequence in the injectors of the diesel engine. In one embodiment such instructions include turning off at least one such injector based on line pressure. Methods in accordance with the present invention may be carried out using suitable processing devices known in the art using suitable software and/or programmed in accordance with the following algorithms. 
     Now referring to  FIG. 2 , a method of conserving fuel in a diesel engine is described whereby engine data is gathered by the sensor and/or the control module, conditions in the engine are detected based on the data received, the control module calculates the firing sequence to spread the firing outage equally among all injectors and transmits firing sequence instructions to the injectors. 
     Now referring to  FIG. 3 , a method of conserving fuel in a diesel engine is described which includes gathering transmission line pressure data, detecting conditions in the transmission based on the received pressure data, calculating a firing sequence for injectors based on the conditions and transmitting firing sequence instructions to the injectors. 
     Now referring to  FIG. 4 , a method of conserving fuel in a diesel engine is described which includes gathering data, detecting conditions in the engine based on received data, calculating the firing sequence for the injectors based on the conditions, determining whether an injector should be turned off and transmitting firing sequence instructions to the injectors. 
     In one embodiment, the function of shutting off any injector in accordance with the present invention does not begin until the motor is already warm, such as 150 degrees F. 
     In a preferred embodiment the function of turning off injectors occurs regardless of the gear; the function preferably initiates as a result of the transmission line pressure principally because the transmission line pressure is proportional to load. The greater the load, the greater the pressure. 
     It will be recognized that the present invention may be employed in any diesel engine regardless of the vehicle or equipment in which the engine is located. 
     It has been found that turning off certain injectors provides significant fuel efficiency, as shown in the accompanying  FIGS. 5-7 . 
     The turning off of the injectors can be varied by the number of cylinders per revolution. For example, if every seventh injector is turned off (see  FIG. 5 ) there will be a fuel savings of approximately 14%. If every fifth injector is turned off, even more fuel is saved ( FIG. 6 ) and if every third injector is turned off even more fuel is saved ( FIG. 7 ). Shutting off every ninth cylinder results in 11% fuel savings; every eleventh results in about 9% fuel savings; every thirteenth results in about 7% savings in fuel and every fifteenth results in about 6% fuel savings. 
     The turning off of the injectors in accordance with the present invention spreads out the outage and balances the engine firing to eliminate shake. 
     By way of example and not limitation, the following Table A depicts a scheme that may be programmed into a control module to determine which injectors will not fire under given line pressure conditions: 
     
       
         
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE A 
               
             
             
               
                   
                   
               
               
                   
                 Line Pressure (psi) 
               
             
          
           
               
                   
                 10 
                 15 
                 20 
                 25 
                 30 
                 35 
                 45 
                 50 
               
               
                   
                   
               
             
          
           
               
                 No. of 
                 — 
                 3rd 
                 5 th   
                 7th 
                 9th 
                 11th 
                 13th 
                 15th 
               
               
                 Injector 
               
               
                 Skipped 
               
               
                   
               
             
          
         
       
     
     While the preferred embodiments have been described and illustrated it will be understood that changes in details and obvious undisclosed variations might be made without departing from the spirit and principle of the invention and therefore the scope of the invention is not to be construed as limited to the preferred embodiment.