Abstract:
The present invention provides a flexible fuel internal combustion engine utilizing impulse charging technology. The internal combustion engine includes a fuel sensor which determines the type of fuel currently being supplied to the engine, for example, either gasoline or E85. Based upon this determination, the impulse charging will be inactive (if gasoline is sensed) or active (if E85 is sensed). A speed or torque sensor is also utilized to determine if impulse charging will produce a volumetric efficiency that is better matched to the fuel octane characteristics.

Description:
FIELD 
     The present disclosure relates to a flexible fuel, internal combustion engine and more particularly to a flexible fuel, impulse charged internal combustion engine and transmission assembly. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     The internal combustion engine, particularly with regard to passenger car and light truck applications, has been the subject of extensive and exhaustive development. One of the more recent improvements involves operation of an internal combustion engine as a flexible fuel engine, i.e., an engine operating on a variety of fuels, most commonly gasoline and E85 (a mixture of 85 percent ethanol and 15 percent gasoline). While a flexible fuel engine presently offers certain advantages from the standpoint of fuel expense and the larger issue of foreign oil dependency, there are operational issues which are the subject of much contemporary research and development. 
     For example, while a typical flexible fuel engine operating on E85 offers performance improvements due to the higher octane of the ethanol that allows the spark timing to be set at more favorable crank angles under heavy load conditions, these improvements are limited because the engine air flow, which is the primary power limiting factor, remains unchanged. Thus, the performance and fuel economy potential of the E85 fuel are not fully realized. 
     Another technology undergoing rapid development is referred to as impulse charging. Here, a rapidly operating, essentially two position impulse valve is disposed in each intake runner between the common air supply and the conventional intake valve. Generally speaking, it is disposed proximate the intake valve such that it defines a relatively short length of intake runner which is opened and closed by the impulse valve in timed relation to the operation of the intake valve. 
     During the first half of the intake stroke, the impulse valve is closed, creating a vacuum. When the impulse valve opens, air is rapidly drawn into the cylinder from the intake manifold. At the end of the intake stroke, the impulse valve rapidly closes to trap a maximum possible amount of air in the intake runner and cylinder downstream of the impulse valve. Air in the runner downstream of the impulse valve is compressed to higher pressures during the first part of the compression stroke while the intake valve is still open. As the intake stroke begins again, this pressurized air enhances scavenging, reduces the in-cylinder temperature and minimizes any pre-ignition tendency. An impulse charged engine typically provides improved volumetric efficiency. 
     Because of the new and developing nature of these technologies, improvements in flexible fuel and impulse charging technologies are both possible and desirable. The present invention relates to an improvement for an internal combustion engine utilizing these technologies. 
     SUMMARY 
     The present invention provides a flexible fuel internal combustion engine and transmission assembly utilizing impulse charging technology. The internal combustion engine includes a fuel sensor which determines the type of fuel currently being supplied to the engine, for example, either gasoline or E85. Based upon this determination, the impulse charging will be inactive (if gasoline is sensed) or active (if E85 is sensed). 
     Since the volumetric efficiency of an engine due to impulse charging changes with engine speed, a speed or torque sensor is also utilized to determine if impulse charging will produce a volumetric efficiency that is better matched to the fuel octane characteristics. If a determination is made that impulse charging will produce a suitable or desirable increase in volumetric efficiency, the engine controller activates an impulse charging controller which operates the impulse charging valves disposed in each of the intake runners of the engine. The fuel system of the engine may be either a port or in-cylinder direct fuel injection type. 
     With the increased engine torque, it is also desirable that the transmission shift and torque converter lockup schedules be adjusted to optimize vehicle performance and fuel economy. 
     Thus it is an object of the present invention to provide a flexible fuel internal combustion engine having adaptive impulse charging and control components. 
     It is a further object of the present invention to provide a flexible fuel internal combustion engine and transmission having adaptive impulse charging and control components. 
     It is a still further object of the present invention to provide a flexible fuel internal combustion engine having impulse charging and control components including a fuel sensor. 
     It is a still further object of the present invention to provide a flexible fuel internal combustion engine having impulse charging and control components which are disabled when the engine is fueled by gasoline. 
     Further advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein, in which like reference numbers in the several drawing Figures refer to the same component, element or feature, are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a diagrammatic illustration of a flexible fuel, impulse charged internal combustion engine and transmission assembly according to the present invention; 
         FIG. 2  is an enlarged, diagrammatic view of a portion of a flexible fuel, impulse charged internal combustion engine according to the present invention; 
         FIG. 3  is a computer or software flowchart of the logic and control steps of an engine controller of a flexible fuel, impulse charged internal combustion engine and transmission assembly according to the present invention; and 
         FIG. 4  is a graph depicting the volumetric efficiency of a prior art flexible fuel, naturally aspirated internal combustion engine and a flexible fuel, impulse charged internal combustion engine according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     With reference to  FIG. 1 , a flexible fuel, impulse charged internal combustion engine and transmission assembly according to the present invention is illustrated and generally designated by the reference number  10 . The engine and transmission assembly  10  include a multiple, typically four, six or eight piston and cylinder internal combustion engine  12  having an output shaft  14  which directly drives a multiple speed, typically automatic transmission  16  which, in turn, drives an output shaft  18 . Operatively associated with the internal combustion engine  12  is an ignition system  22 , a fuel injection system  24  which receives fuel from a fuel sensor  26  and a transmission controller  28  which provides control signals and reads and stores data from the automatic transmission  16 . It should be appreciated that the fuel injection system  24  may be either a port type or in-cylinder, direct injection type. 
     An engine control module  30  (ECM) or similar electronic controller or microprocessor receives data and various operating signals from sensors and transducers associated with the internal combustion engine  12  as well as the associated motor vehicle and its operator (both not illustrated), contains various software, operating algorithms, processors, memory including look up tables and the like and provides various operating signals and data to components and assemblies of the internal combustion engine  12 . Specifically, the engine control module  30  provides control signals to the ignition system  22 , to the fuel injection system  24  and to the transmission controller  28 . Additionally the engine control module  30  receives data from the fuel sensor  26 , from a cam angle or position sensor  32 , from a crankshaft speed sensor  34  and from an exhaust gas sensor  36  disposed in an exhaust pipe  38 . 
     Fuel is provided to the fuel sensor  26  and the fuel injection system  24  of the internal combustion engine  12  through a fuel line  42 . Combustion air is supplied to the internal combustion engine  12  through an air filter (not illustrated) and an air intake manifold  44  having a throttle or flow control  46  driven and adjusted by the engine control module  30 . The intake manifold  44  is connected to an impulse charger manifold  50 . Disposed within the impulse charger manifold  50  are a mass air flow sensor  52  and a manifold air pressure sensor  54 . 
     As illustrated in  FIG. 2 , the impulse charger manifold  50  includes a plurality of intake ducts or runners  56 , only one of which is shown, generally equal in number to the number of cylinders in the internal combustion engine  12 . The intake duct or runner  56  leads to and communicates with one (or more) inlet valves  58  associated with each of the respective cylinders  62  of the internal combustion engine  12 . Disposed in each of the intake ducts or runners  56  generally proximate the inlet valve  58  is an impulse charging valve  64 . The impulse charging valve  64  is preferably a two state or position rotary valve capable of rapid repositioning between open and closed. Configurations other than rotary which operate with the requisite speed are, of course, suitable and considered to be within the scope of this invention. Each of the impulse charging valves  64  is controlled by an actuator  66  which is controlled by an impulse charging controller  70 . The impulse charging controller  70  is, in turn, controlled by the engine control module  30 . 
     Referring now to  FIG. 3 , a flowchart or program  100  of the operation of a flexible fuel, impulse charged internal combustion engine  12  is presented. Typically, this program  100  will be contained and operate in the engine control module  30 . Alternatively, however, it may reside and function in the impulse charging controller  70  if appropriate data exchange occurs between it and the engine control module  30 . Operation according to the flowchart  100  begins with a start or initializing step  102  which clears undesired data and volatile registers, in accordance with conventional practice, to begin a new iteration of the program  100 . The program  100  then moves to a process step  104  which reads a data signal from the fuel sensor  26  and determines the type of fuel being currently provided to the internal combustion engine  12 . The program  100  then moves to a decision point  106  which inquires if there is ethanol or some other alternative constituent present in the fuel. Typically, the decision point  106  will respond YES or NO based upon a threshold or minimum value in the range of 40 to 60 percent so that minimal values such as the previously utilized 10 percent ethanol mixture will result in a NO response whereas fuel mixtures having significant ethanol or other constituent content will result in a YES response. It will be appreciated that the specific range and endpoints will vary according to application variables and performance goals. Accordingly, the foregoing values and range should be viewed as examples only. 
     If the decision point  106  is answered in the negative, the program  100  moves to a process step  108  which deactivates the impulse charging system by sending an appropriate signal or data transmission to the impulse charging controller  70 . Such a signal will, inter alia, ensure that all the actuators  66  fully open the impulse charging valves  64  to inhibit impulse charging. The program  100  then returns to and end or exit point  110 . 
     If the decision point  106  is answered in the affirmative, the program  100  moves to a process step  112  which reads the engine speed from the crankshaft speed sensor  34 . The engine speed may by utilized in subsequent computations directly or it may be conditioned or adjusted to indicate torque by a correction based upon the speed—torque relationship of the particular internal combustion engine  12 . 
     The program  100  then moves to a decision point  114  which inquires whether the engine speed or torque is above or below a certain threshold. If the engine speed or torque is below a certain threshold value where impulse charging would not significantly or materially improve volumetric efficiency, the decision point  114  is exited at NO and the program  100  returns to the process step  108  to deactivate impulse charging and then moves to the end point  110 . If the engine speed or torque is such that impulse charging would improve volumetric efficiency, the decision point  114  is exited at YES. 
     Next, a series of process steps are executed. A process step  116  activates the impulse charging feature of the present invention be sending an appropriate signal to the impulse charging controller  70 . Then a process step  118  sends appropriate signals to the ignition system  22  to adjust the spark timing and to the fuel injection system  24  to adjust for the additional air volume flow. Finally, a process step  120  generates commands to the transmission controller  28  to adjust the shift point schedule of the automatic transmission  16  and the lockup schedule of the torque converter to optimize vehicle performance and fuel economy. The program  100  then executes a short interval timer  122 , preferably less than one second, and returns to the input of process step  112  to update the engine speed. 
     Referring now to  FIG. 4 , two sets of data points are presented which graphically illustrate the improvement in volumetric efficiency possible through the use of impulse charging with an alternative fuel such as E85 in a flexible fuel internal combustion engine. A first set of data points, labeled  130 , presents operation of a naturally aspirated internal combustion engine at various speeds and its corresponding volumetric efficiency. A second set of data points, labeled  140 , presents operation of an impulse charged engine at various speeds and its corresponding volumetric efficiency. Note that, on average, the volumetric efficiency of an impulse charged engine operating between about r.p.m. and 4000 r.p.m. is approximately 20 percent higher than that of a naturally aspirated engine. 
     The foregoing description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.