US 4,368,705 AGranted

Engine control system

AssigneeCaterpillar Tractor Co.

InventorsThomas T. Stevenson, John F. Szentes, Marios C. Zenios

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Abstract

An electronic engine control system (10) utilizing a digital microprocessor (30) for controlling the timing mechanism (13) and fuel pump rack limit (23) to set the engine timing of, and maximum allowable rate of fuel delivery to, an interval combustion engine (11) so that maximum engine performance is obtained with smoke and emissions limited to required EPA levels. A plurality of timing maps (61-64) are provided, for different modes of engine operation, each map having predetermined value timing control signals programmed therein corresponding to the optimal timing advance of a particular engine speed, or particulaoptimoptimal timing advance of a particular engine speed, or particular combination of engine speed and position of the fuel rack (21). A timing map selector (65) identifies the mode of engine operation and selects the appropriate timing map (61-64) to control the timing mechanism (13) by the particular programmed signal for the existing engine speed and fuel rack position. A similar map (71) will output a particular programmed fuel/air signal in accordance with the existing engine speed and timing, the fuel/air signal having been predetermined to correspond to the maximum fuel/air ratio for fuel combustion to meet EPA limits for that engine speed and timing. The fuel/air signal is multiplied (76) in accordance with existing manifold pressure and the resultant fuel delivery signal is used to set the rack limit (23) for maximum allowable fuel delivery to the engine (11).

Claims26

Dependent claims

A control system (10) for an engine-fuel supply system, said engine fuel-supply system including an internal combustion engine (11) having a rotatable crank shaft (211), an operator-controlled throttle (22), a fuel pump (16) for supplying fuel to said engine (11), a first settable engine control means (13) comprising a timing means (13) for driving said fuel pump (16) at a speed proportional to the rotational speed of said crank shaft (211) and at a desired advance angle relative to the rotation of said crank shaft (211) for setting the engine timing advance, said fuel pump (16) having a movable fuel control means (21) for regulating the amount of fuel delivered by said fuel pump (16) to said engine (11), said fuel control means (21) being movable by said throttle (22) in a first direction to increase fuel delivery and in a second direction to decrease fuel delivery, and a second settable engine control means (23) comprising a fuel control limit means (23) for limiting movement of said fuel control means (21) in said one direction thereof, said control system (10) comprising:

first condition signal means (38) for generating a first condition signal having a value proportional to the speed of said engine (11);
second condition signal means (37) for generating a second condition signal having a value proportional to the distance that said fuel control means (21) has been moved;
third condition signal means (26) for generating a fluid condition signal having a value proportional to the magnitude of engine timing advance set by said timing means (13);
timing control signal means (61,63 or 64) for storing a plurality of timing advance control signals, each timing advance control signal having a predetermined value corresponding to a desired setting of said timing means (13) for engine operation at a particular combination of engine speed and fuel control means position and for generating a timing advance control signal having the predetermined value corresponding to the particular values of the first and second condition signals generated by said first (38) and second (37) condition signal means;
fuel control means limit control signal means (71,76,77,72) for storing a plurality of fuel control means limit control signals, each fuel control means limit control signal having a predetermined value corresponding to a desired setting of the position of said fuel control means limit for engine operation at a particular combination of engine speed and engine timing and for generating a fuel control means limit position control signal having the predetermined value corresponding to the first and third condition signals generated by said first and third condition signal means (38,26);
means (18) for setting said timing means (13) in accordance with the value of the generated advance control signals;
and
means (24) for setting the position of said fuel control means limit (23) in accordance with the value of the generated fuel control means limit position control signal.

5 more elements

A control system (10) for a diesel engine-fuel supply system, said engine fuel-supply system including an internal combustion engine (11) having a rotatable crank shaft (211), an operator-controlled throttle (22), a fuel pump (16) for supplying fuel to said engine (11), timing means (13) for driving said fuel pump (16) at a speed proportional to the rotational speed of said crank shaft (211) and at a desired advance angle relative to the rotation of said crank shaft (211) for setting the engine timing advance, said fuel pump (16) having a fuel control means (21) controllable by said throttle (22) for regulating the amount of fuel delivered by said fuel pump (16) to said engine (11), and a movable fuel control limit means (23) for limiting the maximum amount of fuel delivered by said fuel control means (21) in said one direction thereof, said control system (10) comprising:

means (38) for generating an engine speed signal having a value proportional to actual engine speed;
means (37) for generating a fuel control means signal having a value indicative of the setting of said fuel control means (21);
first timing advance control signal means (61,63) for generating a first set of timing advance control signals each having a predetermined value in response to a desired engine timing advance for a first mode of engine operation and for a particular combination of actual engine speed and fuel control means position, and second timing advance control signal means (62,64) for generating a second set of timing advance control signals each having a predetermined value in response to a desired engine timing advance for a second mode of engine operation and for a particular combination of actual engine speed and fuel control means position;
means (29,47) for delivering said generated engine speed and fuel control means setting signals to said timing control means (61,63 or 64);
and,
means (18) for controlling said timing means in response to said timing advance control signals to set the timing advance of said engine (11) to the value of a generating timing advance control signal.

3 more elements

A control system (10) for an engine-fuel supply system, said engine fuel-supply system including an internal combustion engine (11) having a rotatable crank shaft (211), an operator-controlled throttle (22) a fuel pump (16) for supplying fuel to said engine (11), timing means (13) for driving said fuel pump (16) at a speed proportional to the rotational speed of said crank shaft (211) and at a desired advance angle relative to the rotation of said crank shaft (211) for setting the engine timing advance, said fuel pump (16) having a fuel rack (21) movable by said throttle (22) for regulating the amount of fuel delivered by said fuel pump (16) to said engine (11), said fuel rack (21) being movable in a first direction to increase fuel delivery and in a second direction to decrease fuel delivery, and a movable rack limit means (23) for limiting movement of said fuel rack (21) in said one direction thereof, said control system comprising:

means (18) for generating a timing advance signal having a value proportional to actual engine timing advance;
means (38) for generating an engine speed signal having a value proportional to actual engine speed;
fuel/air signal generating means (71) for generating a plurality of fuel/air signals each having a predetermined value for a predetermined combination of a predetermined combination of timing advance angle and engine speed and for generating one of said fuel/air signals in response to application of a particular value timing advance signal and a particular engine speed signal to said fuel/air signal generating means (71);
means (29,48) for applying said timing advance and engine speed signals to said fuel/air signal generating means;
means (40) for generating a manifold pressure signal having a value proportional to the magnitude of manifold air pressure;
means (76,77) for generating a fuel delivery signal proportional to the value of said fuel/air signal divided by the value of said manifold pressure signal;
rack limit control means (72) for generating a plurality of rack limit position control signals each having a predetermined value for a predetermined combination of fuel delivery and engine speed and for generating one of said rack limit position control signals in response to application of a particular value fuel delivery signal and a particular value engine speed signal to said rack limit control means;
and
means (24) for moving said rack limit in response to said rack limit position control signals to the position determined by the values of the generated rack limit position control signal.

6 more elements

Dependencies are inferred from the claim text.