Internal-combustion engines – Engine speed regulator – Open loop condition responsive
Reexamination Certificate
2001-10-24
2003-12-02
Mohanty, Bibhu (Department: 3747)
Internal-combustion engines
Engine speed regulator
Open loop condition responsive
Reexamination Certificate
active
06655351
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is directed to combines and other off-road vehicles powered by internal combustion engines, wherein one or more auxiliary power demands are periodically placed on the engine. The invention is further directed to such vehicles wherein the engine is controlled by an electronic engine control unit as part of an electronic engine control system.
Combines are large agricultural machines used to harvest grain or other crop material from supporting plants. Such harvesting of the crop material includes e.g. cutting plants containing such crop material or otherwise severing the crop material from the plant, threshing and separating the crop material from the plant material, and cleaning the crop material from the supporting plant material and other debris with which the crop material may be associated. Such combine typically has a grain tank for temporarily storing harvested crop material. The combine also has an unloading auger for unloading the crop material from the grain tank to a grain cart or truck. Combines may further be provided with additional crop processing assemblies such as straw choppers and chaff spreaders. Combines are typically embodied in self-propelled vehicles.
A typical combine uses a single engine to power all machine functions, including the various operations noted above, in addition to powering movement of the vehicle from place to place in the normal course of operation. Thus, the load on the engine varies in accord with the loads applied by the various assemblies which are activated, operated, and deactivated during routine use of the machine.
A typical such combine operates at a set engine speed. Typical combines have two or three speed settings which correspond, for example, to “low” speed, “medium” speed, and “high” speed. Each of such speeds has a target engine rotation speed. For example, “low” speed can have a target engine speed of about 1200 rpm. “Medium” speed can have a target engine speed of about 1600 rpm. “High” speed can have a target engine speed of about 2200 rpm.
The speed setting is set by the vehicle operator. Once the vehicle operator selects a speed setting, an electronic engine control unit (ECU) controls the engine speed according to the selected setting, primarily by dynamically adjusting the quantity of fuel injected into the engine cylinders. When the operator makes a different speed selection, the engine control unit responds by changing the quantity of fuel being injected into the cylinders, in order to maintain the engine speed at the predetermined target engine speed.
A primary task of the ECU is to dynamically maintain the engine speed constant in the face of whatever loads are being imposed on the engine. As a load is imposed which causes the engine rpm to decrease below a first predetermined speed, the engine control unit increases the quantity of fuel being injected into the cylinders, in order to increase the amount of power being developed by the engine, and thus to maintain engine speed within a target range between the first and second predetermined speeds.
Similarly, as a load is removed or decreased which causes the engine speed to increase above a second predetermined level, the engine control unit decreases the quantity of fuel being injected into the cylinders, in order to decrease the amount of power being developed by the engine, thus to maintain engine speed within the target range between the first and second predetermined speeds.
Thus, conventional engine control units respond to engine speed changes by changing the fuel flow to the cylinders in attempting to maintain engine speed within a range of predetermined engine speeds.
While the ECU thus responds reactively, step changes in engine loading can cause substantial decreases in engine speed before the engine control unit can respond to the dynamically changing situation.
U.S. Pat. No. 4,522,553 issued Jun. 11, 1985 to Nelson et al teaches boosting engine power by a predetermined amount to a fixed higher level when the unloading auger is switched on, and correspondingly reducing the engine power by a corresponding predetermined amount to a fixed lower level when the unloading auger is switched off.
However, the wide range of operating systems which consume power in the combine results in a constantly varying load demand being placed on the engine and engine drive train. To the extent multiple load demands increase simultaneously, to the extent a load demand increases step-wise by a substantial amount, the engine may become overloaded such that the engine speed drops below an acceptable speed. When the engine speed drops below such acceptable speed, engine systems such as engine cooling and lubrication can be affected so as to reduce engine wear life. In addition, the ability of the engine to sustain operation, and/or to recover to desired operating speed, when an excessive load is applied, may be jeopardized. Where an unexpected heavy load is coupled with a load change which can be predicted, the combined affect of the predictable load and the unexpected load can have a negative affect on overall engine operation, or user perception of engine operation. However, if certain load changes can be predicted and anticipated, and engine power adjusted pro-actively to such anticipated loads, the detrimental coupling affect of concurrent unexpected load increases can be lessened or avoided.
It is an object of the invention to provide an engine power control system, including an electronic engine control unit and a fuel system including a fuel supply pump and adjustment apparatus which, in combination, make incremental changes in power output of the engine in anticipation of incrementally progressive changes in load demand on the engine.
It is another object to provide an engine power control system, including an electronic engine controller and a fuel system including a fuel supply pump and adjustment apparatus which, in combination makes incremental changes in power output of the engine in anticipation of load demands on the engine, in combination with making further changes in power output of the engine in reaction to sensed engine-loading changes which are not satisfied by the anticipatory changes.
Yet another object is to provide methods of providing pro-active, anticipatory changes in inputs to engine power.
Still another object is to provide methods of providing both pro-active anticipatory changes in inputs to engine power and reactive changes in inputs to engine power in response to sensed engine-loading changes which are not satisfied by the pro-active anticipatory changes.
SUMMARY OF THE DISCLOSURE
In this invention, an engine control unit uses a power curve or an algorithm for a power curve to pro-actively adjust fuel flow rate to an internal combustion engine, thereby to adjust engine power, in anticipation of changes in loads being imposed on the engine. In the alternative, the engine control unit can combine input from such pro-active algorithm with input from a reactive algorithm, thus to develop a combined fuel flow rate control signal to fuel injectors at the engine.
A first family of embodiments of the invention comprehends, in an engine-driven vehicle, an engine power control system controlling the power output of the engine. The engine power control system comprises a fuel system including a fuel supply pump and adjustment apparatus which adjusts the rate at which fuel is delivered to combustion chambers of the engine in response to control signals supplied to an input of the adjustment apparatus, thereby to adjust power output of the engine; and an electronic engine controller capable of generating, and delivering to the adjustment apparatus, a series of control signals which cause the adjustment apparatus to change the rate at which fuel is delivered to the combustion chambers thereby to change the power output of the engine. The electronic engine controller has at least one of a power curve or an algorithm for a power curve stored in memory which, responsive to certain predetermined operating condition
Brockmann William A.
Hennings Kenny L.
Sahlin Mark Peter
Sheidler Alan David
Tingle Kyle John
Deere & Company
Mohanty Bibhu
Wilhelm Thomas D.
Wilhelm Law Service
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