The present invention relates to charge forming systems, and more particularly to a system which automatically and continuously seeks an optimum air/fuel mixture.
The provision of an instantaneously correct fuel/air mixture to an internal combustion engine over a full range of speeds and loads has for years occupied countless engineers, technicians and inventors. Accordingly, the charge forming apparatus have progressed over the years from crude mixing devices to complex, sophisticated carburetion and fuel injection systems. Nonetheless, it is recognized that to date no charge forming system has been implemented which will provide the ideal fuel/air mixture to an internal combustion engine over a complete operating range.
Of the various approaches to charge forming systems, two basic lines of attack may be discerned. With one approach, air inflow is controlled by a throttle or the like and fuel is caused to be entrained with the passing air, in response to the air flow characteristics. The metering of the mixing apparatus is such that a relatively constant, predictable mixture results over the anticipated air flow range. This is the basic rule of operation of the carburetor, which is of course the predominant charge forming mechanism used with internal combustion engines. The same thesis, however, has also been implemented in many forms of fuel injection apparatus.
The second approach referred to above may be referred to as a "programmed" approach inasmuch as the charge forming system is "programmed" or adjusted to respond to certain stimuli to effect a desired fuel/air ratio. The stimuli applied to such systems may include temperature, pressure, engine speed, and the like. Conventionally, such systems make use of not one but a plurality of stimuli in order to more accurately react to inferred engine operating conditions. Charge forming systems of this type thus react to given types of stimuli in a predetermined manner, effecting a fuel/air ratio which is assumed to be the "correct" one for the engine. In theory this approach should work well, assuming that a great number of preprogrammed responses are available to correspond to the almost limitless combinations of stimuli which occur over the full range of operation for most internal combustion engines, especially those used in vehicles.
In recent years the increased recognition of environmental degradation caused by internal combustion engine exhaust, along with the need for economical operation, has caused renewed interest in more efficient and sophisticated charge forming control systems. Generally, the approach taken in developing more responsive charge control systems has been to make use of the most modern and sophisticated technology, particularly in the field of electronics, to accommodate the functional complexities which are inherent in the "programmed" type of system. Accordingly, control systems which are in effect small analog or digital computers are created which can "tailor" a fuel/air ratio to a given operating condition, as evidenced by various stimuli. The stimuli or sensed parameters include exhaust gas temperature and composition, engine temperature, combustion pressure, inlet manifold and/or venturi vacuum, engine speed, along with many other operating parameters. However, inasmuch as these systems all provide a fixed, predetermined response to a given set of stimuli, they cannot be flexible enough to find the true optimum fuel/air ratio for all operating conditions, but rather provide mixture ratios which are only assumed to be correct.
Accordingly, it will be appreciated that it would be desirable to provide an improved charge forming system which consistently achieves the actual optimum fuel/air ratio for any given operating condition.
It is therefore an object of the present invention to provide an improved charge forming system for optimizing the mixture ingested by an internal combustion engine over a broad operating range.
It is another object of the present invention to provide an improved charge forming system which does not provide a predetermined or programmed mixture to an internal combustion engine.
Yet another object is to provide an improved fuel metering system for supplying vaporized fuel to an internal combustion engine.
It is a further object to provide a charge forming system for an internal combustion engine which effects a marked reduction in the output of pollutants by the engine.