Method for engine control

• US 5,445,128 A
• Filed: 08/27/1993
• Issued: 08/29/1995
• Est. Priority Date: 08/27/1993
• Status: Expired due to Term

• Current Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Original Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Inventors: Babcock, Douglas J., Letang, Dennis M., Weisman, S. Miller II
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US08/113,424
• Time in Patent Office: 732 Days
• Field of Search: 123/436, 123/500, 123/501, 123/502, 123/503, 123/506
• US Class Current: 123/436
• CPC Class Codes: B60K 2031/0091 Speed limiters or speed cutters
• CPC Class Codes: B60K 31/045 in a memory, e.g. a capacitor
• CPC Class Codes: B60K 31/047 the memory being digital
• CPC Class Codes: B60W 2050/0022 Gains, weighting coefficients or weighting functions
• CPC Class Codes: B60W 2050/0042 Transfer function lag; delays
• CPC Class Codes: B60W 2050/0052 Filtering, filters
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/0676 Engine temperature
• CPC Class Codes: B60W 2710/0616 Position of fuel or air injector
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: F01P 2023/00 Signal processing; Details thereof
• CPC Class Codes: F01P 2023/08 Microprocessor; Microcomputer
• CPC Class Codes: F01P 2025/08 Temperature
• CPC Class Codes: F01P 2025/13 Ambient temperature
• CPC Class Codes: F01P 2025/40 Oil temperature
• CPC Class Codes: F01P 2025/46 Engine parts temperature
• CPC Class Codes: F01P 2031/00 Fail safe
• CPC Class Codes: F01P 7/04 by varying pump speed, e.g. by changing pump-drive gear ratio
• CPC Class Codes: F01P 7/048 using electrical drives
• CPC Class Codes: F01P 7/08 by cutting in or out of pumps
• CPC Class Codes: F02B 3/06 : with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02D 2041/1432 : the system including a filter, e.g. a low pass or high pass filter
• CPC Class Codes: F02D 2200/1015 : Engines misfires
• CPC Class Codes: F02D 2200/501 : Vehicle speed
• CPC Class Codes: F02D 2250/18 : Control of the engine output torque
• CPC Class Codes: F02D 2250/38 : Control for minimising smoke emissions, e.g. by applying smoke limitations on the fuel injection amount
• CPC Class Codes: F02D 31/007 : controlling fuel supply
• CPC Class Codes: F02D 31/009 : for maximum speed control
• CPC Class Codes: F02D 41/008 : Controlling each cylinder individually
• CPC Class Codes: F02D 41/0085 : Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
• CPC Class Codes: F02D 41/12 : for deceleration F02D41/0005, F02D41/107 take precedence
• CPC Class Codes: F02D 41/1498 : measuring engine roughness
• CPC Class Codes: F02D 41/40 : with means for controlling injection timing or duration
• CPC Class Codes: F02D 41/402 : Multiple injections
• CPC Class Codes: F02D 41/403 : with pilot injections
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

A method for comprehensive integrated control of a compression-ignition internal combustion engine having integral fuel pump-injectors utilizing an electronic control unit is disclosed. The control strategy integrates various functions of engine control including fuel delivery, cooling fan control, engine speed governing and overspeed protection, engine braking, torque control, and vehicle speed diagnostics and control. Cooling fan control is integrated with vehicle speed diagnostics and control as well as fuel delivery to provide an integrated cruise control function which incorporates engine braking. The method also includes improved control over the various engine speed governors while improving idle quality by balancing the power delivered by each of the engine cylinders when at idle. The integrated torque control employs functions to reduce NOx emissions and noise utilizing adaptive fuel delivery timing and a split injection strategy.

Claims

1. A method of controlling the output torque of a multi-cylinder compression-ignition internal combustion engine including an electronic control unit for controlling the engine, a plurality of cylinders each having an injector apparatus controlled by the electronic control unit for delivering fuel, the method comprising:

sensing at least one engine operating parameter to obtain at least one operating signal;

determining a desired output torque for each cylinder based on the at least one operating signal;

determining a base fuel pulse width for each cylinder to produce the desired output torque;

determining a pulse width adjustment factor for each cylinder for modifying the base fuel pulse width according to;

space="preserve" listing-type="equation">TMP=PWA.sub.old +G*(RPM.sub.bal -RPM.sub.avg)

space="preserve" listing-type="equation">PWA.sub.new =max(-ACBr.sub.LIM, min(ACB.sub.LIM, TMP))

wherein "max()" is a function which selects the largest of the parenthetical values, "min()" is a function which selects the smallest of the parenthetical values, ACB_LIM is a limiting value for the adjustment, G represents a system gain factor, RPM_bal is a balancing value of the engine rotational speed for the current cylinder, and RPM_avg is an average of the balancing values of previously fired cylinders; and

controlling the injector apparatus based on the modified base fuel pulse width.

2. A method of controlling the output torque of a multi-cylinder compression-ignition internal combustion engine including an electronic control unit for controlling the engine, a plurality of cylinders each having an injector apparatus controlled by the electronic control unit for delivering fuel, the method comprising:

sensing at least one engine operating parameter to obtain at least one operating signal;

determining a desired output torque for each cylinder based on the at least one operating signal;

determining a base fuel pulse width for each cylinder to produce the desired output torque;

determining a pulse width adjustment factor for each cylinder for modifying the base fuel pulse width based on the at least one operating signal, wherein the pulse width adjustment factor is normalized to have an average value of zero after every firing cycle in which each of the plurality of cylinders has fired once; and

controlling the injector apparatus based on the modified base fuel pulse width.

3. The method of claim 2 wherein the engine includes a plurality of pistons disposed within the plurality of cylinders, the method further comprising determining a pulse width adjustment time for each cylinder for modifying the pulse width according to the equation:

##EQU6## wherein PWAT represents the pulse width adjustment time, PWA represents the pulse width adjustment factor, and RPM_inst represents the instantaneous engine rotational speed which is calculated based on the change of position of the piston within the cylinder immediately prior to scheduling the fuel pulse.

4. The method of claim 2 wherein determining the pulse width adjustment factor is performed only periodically if a first set of conditions is met but performed before every cylinder firing if a second set of conditions is met in addition to the first set of conditions.

5. The method of claim 2 wherein determining the desired output torque comprises:

determining a plurality of possible engine output torque values based on the at least one engine operating signal; and

selecting the smallest of the plurality of engine output torque values.

6. The method of claim 5 wherein the engine includes a slave electronic control unit for controlling engine subsystems and the plurality of possible output torque values comprises a rampdown torque, a slave rampdown torque, a smoke-control torque, and a low-gear torque.

7. The method of claim 6 wherein the rampdown torque is the lesser of a stop-engine torque, an over-temperature torque, and a marine torque limit, and wherein the marine torque limit is determined according to:

##EQU7## wherein D_TQLMT is the desired torque limit;

TQ_ADJ is a torque adjustment parameter;

tq_tret is a torque timer ending time;

MAX_TQ is a maximum allowable torque;

tq_trst is a torque timer starting time; and

TMR represents a torque limiting timer.

8. The method of claim 7 wherein the at least one engine operating parameter includes engine oil temperature and wherein the over-temperature torque decreases as a first-order lag function of the average engine torque.

9. The method of claim 6 wherein the engine is operably connected to a transmission and the low-gear torque is a constant value based on the rated torque capacity of the transmission.