Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Patent
1993-07-14
1995-06-27
Nelli, Raymond A.
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
F02M 5100
Patent
active
054270839
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of determining the mass of air induced per cycle to an internal combustion engine for the purposes of controlling the air/fuel ratio as part of the engine management system.
It is known to use various types of mass air flow sensors in the air induction system of an engine to determine the mass rate of air induced into the engine over the full range of operating conditions of the engine. Other means for determining the air flow have also been used, such as providing a calibration in the memory of an ECU (electronic calculating unit) of air flow in relation to engine speed and throttle position.
Although these known techniques for determining the mass of induced air are effective, they have disadvantages either from the point of view of the nature of the equipment required, including the cost and effective life thereof, and/or the quantity of memory capacity required to store relevant information.
It is therefore the object of the present invention to provide a method of determining the mass of air introduced to an internal combustion engine under operating conditions which is effective, and requires less hardware and/or memory storage capacity to provide an effective control of the air/fuel ratio of the engine under all operating conditions.
With this object in view, there is provided according to the present invention a method of determining the mass of air introduced per cylinder per cycle (IACC) of an internal combustion engine comprising the steps of: engine speed and operating conditions, between IACC.sub.WOT and IACC at preselected part-load the coefficient relating to the current load and speed; and
applying said selected coefficient to said IACC.sub.WOT to determine the current IACC (IACC.sub.LD).
More specifically, there is provided a method of determining the mass of air introduced per cylinder per cycle (IACC) of an internal combustion engine comprising: engine at wide open throttle (WOT) (IACC.sub.WOT) over a selected engine speed operating range, selected load demands below WOT over said selected engine speed range, selecting the respective coefficients for the sensed engine speed and load demand, sensed engine load demand at the sensed engine speed conditions (IACC.sub.CALC), and the required mass of fuel per cylinder per cycle (FPC).
On the basis of this determined FPC, a signal is issued to a fuel metering means to activate same to deliver to the engine FPC amount of fuel in timed relation to the engine cycle.
Conveniently the processor is programmed so the algorithm adjusts the IACC.sub.WOT in response to variations in selected engine operating conditions such as intake air temperature or pressure, or exhaust pressure. The selected engine operating conditions may be related to respective datum values, the datum values preferably are the values of the respective engine operating condition existing at calibration of the IACC coefficients stored in the memory.
The processor may be programmed so that if one or more of the engine operating conditions is sensed to be fluctuating regularly within a relatively short time interval, the effects of the fluctuations on the air mass calculation will be limited. The limiting of the effect of the fluctuations is preferably carried out within a select range of load demand and/or engine speed, preferably in the lower range. Alternatively, if it is known that the intended use of the engine can give rise to such fluctuation at certain operating conditions, then the processor program can be adapted to limit the effect of such fluctuation whenever it is operating at those certain operating conditions, irrespective of whether such fluctuation is or is not occurring. By way of example a marine engine operating at low speed such as while trolling may pass through a series of waves which will cause a near cyclic variation in exhaust pressure. This in turn may cause the engine to "hunt" for a stable operating condition. By reducing the effect of exhaust pressure the "hunting" can be reduced or eliminated.
In a preferred form, the m
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patent: 5239965 (1993-08-01), Ninomiya
patent: 5239971 (1993-08-01), Uchinami
Nelli Raymond A.
Orbital Engine Company (Australia) Pty. Limited
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