Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1998-04-21
1999-10-26
Solis, Erick R.
Internal-combustion engines
Charge forming device
Fuel injection system
123492, F02M 5100
Patent
active
059709545
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the control of fuelling to an engine and, more particularly, to a method of control of fuelling to an engine when in transition from an idle to an off-idle condition of operation.
There is known from the Applicant's Australian Patent Application No. 34862/93 a fuel based control system for an engine. In such a system, the fuel per cylinder per cycle (FPC) is set as a function of operator demand as measured, for example, by sensed throttle pedal position and engine speed. The fuelling level set in response to operator demand may be characterised as FPC.sub.DEMAND and may be variable. The engine management system employed for the fuel based control strategy also determines a fuel per cycle amount applicable to idle conditions. This fuelling level is typically determined from the output of a conventional closed loop idle control strategy in the known manner together with an idle demand input which may be characterised overall as FPC.sub.IDLE. Hence, there are definable operating conditions being idle operation and off-idle or operator demand operation.
In addition to the FPC components described above, offsets to FPC may be provided. These offsets may characteristically be additional amounts of fuel for when, for example, the engine is cold and frictional forces will be larger than during normal operation, or which relate to situations such as when additional engine loads are present, for example, when an air-conditioner is activated.
The total FPC to the engine, being the actual amount of fuel delivered to the engine, may then be established by the following formulae which: would apply for different operating conditions: map)+FPC.sub.IDLE (from PID controller)+FPC.sub.OFFSETS. operator demand on the engine, however, a base idle fuelling value (FPC.sub.IDLE DEMAND) is provided from an idle FPC map to which a further FPC value as determined by an idle or PID controller is added (FPC.sub.IDLE).
As all engines have different friction levels associated therewith, FPC.sub.TOTAL for a particular idle speed (i.e FPC.sub.TOTAL-IDLE) can vary from engine to engine as a function of such friction. Further, FPC.sub.TOTAL-IDLE may also vary on the basis of previous operating conditions. As an example, FPC.sub.TOTAL-IDLE may be lower for an engine which has been operating for a certain period of time and hence is warm as compared to an engine which has just been started. Still further, other engine specific and application specific factors may result in some engine to engine variation of FPC.sub.TOTAL-IDLE. For example, in the case of marine engines, the type and pitch of the propeller used will have an effect on FPC.sub.TOTAL-IDLE. This latter case may be quite significant as in such marine applications it is possible to be at idle in neutral or at idle whilst in gear. Hence the FPC.sub.TOTAL-IDLE could be quite different for each situation. Accordingly, a problem may arise on leaving idle and moving to an off-idle operating condition, for example, when engaging a gear and applying some operator demand in a marine application.
On leaving idle, a condition may arise wherein the new fuelling level determined by the engine management system, FPC.sub.TOTAL OFF-IDLE. may be below the previous FPC.sub.TOTAL-IDLE value causing a loss in speed of the engine and possible stalling which is undesirable.
It is the object of the present invention to provide a method of control of fuelling to an engine that substantially reduces or eliminates any loss or drop in engine speed during the transition between fuelling at idle and fuelling off-idle.
With this object in view, the present invention provides a method of control of fuelling to an engine in transition between idle and off-idle operating modes including; control means determines a fuelling level to the engine at least greater than FPC.sub.TOTAL OFF-IDLE.
Preferably, the control means determines a fuelling level to the engine by incrementing FPC.sub.TOTAL-OFF IDLE by a controlled value FPC.sub.INC. Conveniently, FPC.sub.TOTAL-OFF IDLE is incremented before
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Hurley Richard William
Melbourne Keith
Worth David Richard
Orbital Engine Company (Australia) Pty Limited
Solis Erick R.
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