Method for generating a homogeneous mixture for auto-ignition internal combustion engines and for controlling the combustion process

• US 6,543,411 B2
• Filed: 02/23/2001
• Issued: 04/08/2003
• Est. Priority Date: 02/26/2000
• Status: Expired due to Fees

• Current Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Schnabel, Martin, Raab, Alois
• Primary Examiner(s): Wolfe, Willis R.
• Application Number:
  US09/792,591
• Publication Number:
  US 20010017123A1
• Time in Patent Office: 774 Days
• Field of Search: 123/299, 123/305, 123/316, 123/58.8, 123/90.15, 123/90.16, 123/568.11, 123/568.12, 123/568.14
• US Class Current: 123/305
• CPC Class Codes: F02B 1/12 with compression ignition with fuel-air charge ignited by compression ignition of an additional fuel F02B7/00
• CPC Class Codes: F02B 29/0412 Multiple heat exchangers arranged in parallel or in series
• CPC Class Codes: F02B 29/0456 Air cooled heat exchangers
• CPC Class Codes: F02B 29/0481 Intake air cooling by means others than heat exchangers, e.g. by rotating drum regenerators, cooling by expansion or by electrical means
• CPC Class Codes: F02B 29/0493 Controlling the air charge temperature
• CPC Class Codes: F02B 37/00 Engines characterised by provision of pumps driven at least for part of the time by exhaust
• CPC Class Codes: F02B 47/08 the substances including exhaust gas
• CPC Class Codes: F02B 75/02 Engines characterised by their cycles, e.g. six-stroke
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 41/006 using internal EGR control of valve overlap for internal EGR F02D13/0261; arrangements for internal EGR F02M26/01
• CPC Class Codes: F02D 41/3035 a mode being the premixed charge compression-ignition mode
• CPC Class Codes: F02M 26/01 Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/07 Mixed pressure loops, i.e. wherein recirculated exhaust gas is either taken out upstream of the turbine and reintroduced upstream of the compressor, or is taken out downstream of the turbine and reintroduced downstream of the compressor
• CPC Class Codes: F02M 26/08 for engines having two or more intake charge compressors or exhaust gas turbines, e.g. a turbocharger combined with an additional compressor
• CPC Class Codes: F02M 26/43 in which exhaust from only one cylinder or only a group of cylinders is directed to the intake of the engine
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for generating a homogeneous mixture for auto-ignition internal combustion engines and for controlling the combustion process, the internal combustion engine having an injection system and at least one cylinder/piston unit connected to an intake device, includes the steps of:

a) exhaust-gas recirculation of hot exhaust gas from a previous combustion cycle into the combustion space or into the intake device or exhaust-gas retention of this exhaust gas in the combustion space or in the intake device;

b) injection of fuel by the injection system into the retained or recirculated hot exhaust gas in order to generate a homogeneous fuel/air mixture; and

c) cooling of the homogenized fuel/air mixture by expansion cooling or by isentropic compression in the respective cylinder/piston unit and/or by expansion cooling or by external cooling of a fuel/air mixture homogenized in at least one further cylinder/piston unit and recirculation of the cooled fuel/air mixture into the intake device.

Claims

1. A method for generating a homogeneous mixture for an auto-ignition internal combustion engine and for controlling a combustion process, the internal combustion engine including an injection system and at least one cylinder/piston unit connected to an intake device and having a combustion space, wherein the internal combustion engine includes an exhaust gas turbocharger device and the intake device includes a compressor and a charge-air cooler disposed downstream of the compressor, wherein the compressor is configured to compress combustion air and the charge-air cooler is configured to cool the combustion air, the method comprising the steps of:

one of recirculating hot exhaust gas from a previous combustion cycle into one of the combustion space and the intake device and retaining hot exhaust gas in one of the combustion space and the intake device;

injecting fuel by the injection system into the one of the recirculated hot exhaust gas and the retained hot exhaust gas to generate a homogeneous fuel/air mixture;

cooling the homogenized fuel/air mixture by at least one of expansion cooling in the respective cylinder/piston unit, isentropic compression in the respective cylinder/piston unit, expansion cooling of fuel/air mixture homogenized in at least one further cylinder/piston unit, external cooling of a fuel/air mixture homogenized in at least one further cylinder/piston unit;

further cooling the combustion air by a selectively single-stage or two-stage expansion turbine disposed downstream of the charge-air cooler;

recirculating the cooled fuel/air mixture into the intake device;

feeding the homogeneous fuel/air mixture into the intake device selectively in at least one connecting point, one connecting point being arranged upstream of the compressor, one connecting point being disposed between the compressor and the charge-air cooler, and one connecting point being disposed between the charge-air cooler and an intake manifold of the internal combustion engine; and

supplying the homogeneous fuel/air mixture to the intake device at an additional connecting point disposed between the charge-air cooler and the expansion turbine.

2. A method for generating a homogeneous mixture for an auto-ignition internal combustion engine and for controlling a combustion process, the internal combustion engine including an injection system and at least one cylinder/piston unit connected to an intake device and having a combustion space, the combustion process including a four-stroke process, which includes an intake stroke, a compression stroke, a working stroke and an exhaust stroke, wherein the compression stroke includes an isentropic compression, the method comprising the steps of:

one of recirculating hot exhaust gas from a previous combustion cycle into one of the combustion space and the intake device and retaining hot exhaust gas in one of the combustion space and the intake device;

injecting fuel by the injection system into the one of the recirculated hot exhaust gas and the retained hot exhaust gas to generate a homogeneous fuel/air mixture;

cooling the homogenized fuel/air mixture by at least one of expansion cooling in the respective cylinder/piston unit, isentropic compression in the respective cylinder/piston unit, expansion cooling of fuel/air mixture homogenized in at least one further cylinder/piston unit, external cooling of a fuel/air mixture homogenized in at least one further cylinder/piston unit; and

recirculating the cooled fuel/air mixture into the intake device.

3. A method for generating a homogeneous mixture for an auto-ignition internal combustion engine and for controlling a combustion process, the internal combustion engine including an injection system and at least one cylinder/piston unit connected to an intake device and having a combustion space, the method comprising the steps of:

one of recirculating hot exhaust gas from a previous combustion cycle into one of the combustion space and the intake device and retaining hot exhaust gas in one of the combustion space and the intake device;

injecting fuel by the injection system into the one of the recirculated hot exhaust gas and the retained hot exhaust gas to generate a homogeneous fuel/air mixture;

cooling the homogenized fuel/air mixture by at least one of expansion cooling in the respective cylinder/piston unit, isentropic compression in the respective cylinder/piston unit, expansion cooling of fuel/air mixture homogenized in at least one further cylinder/piston unit, external cooling of a fuel/air mixture homogenized in at least one further cylinder/piston unit; and

recirculating the cooled fuel/air mixture into the intake device.

4. The method according to claim 3, wherein the combustion process includes a four-stroke process, which includes an intake stroke, a compression stroke, a working stroke and an exhaust stroke.

5. The method according to claim 3, wherein the one of the retaining and recirculating step includes the substep of one of retaining and recirculating at least part of the exhaust gas of a dispenser cylinder of the internal combustion engine;

wherein the fuel injecting step includes the substep of injecting fuel into the part of the exhaust gas to generate a homogeneous fuel/air mixture for the dispenser cylinder and for remaining cylinders of the internal combustion engine;

and wherein the cooling step includes the substep of at least one of cooling the homogeneous fuel/air mixture before being fed into a common intake device of the dispenser cylinder and the remaining cylinders in a cooling device by at least one of a compressor refrigerating process, an adsorption refrigerating process, a gas refrigerating process, a steam-jet refrigerating process and an electrothermal process and expansion cooling the homogeneous fuel/air mixture in the cylinders after being fed into the intake device.

6. The method according to claim 3, wherein the internal combustion engine includes an exhaust gas turbocharger device and the intake device includes a compressor and a charge-air cooler disposed downstream of the compressor, the method further comprising the step of feeding the homogeneous fuel/air mixture into the intake device selectively in at least one connecting point, one connecting point being arranged upstream of the compressor, one connecting point being disposed between the compressor and the charge-air cooler, and one connecting point being disposed between the charge-air cooler and an intake manifold of the internal combustion engine.

7. A method for generating a homogeneous mixture for an auto-ignition internal combustion engine and for controlling a combustion process, the internal combustion engine including an injection system and at least one cylinder/piston unit connected to an intake device and having a combustion space, the combustion process including a four-stroke process, which includes an intake stroke, a compression stroke, a working stroke and an exhaust stroke, the method comprising the steps of:

one of recirculating hot exhaust gas from a previous combustion cycle into one of the combustion space and the intake device and retaining hot exhaust gas in one of the combustion space and the intake device;

injecting fuel by the injection system into the one of the recirculated hot exhaust gas and the retained hot exhaust gas to generate a homogeneous fuel/air mixture;

cooling the homogenized fuel/air mixture by at least one of expansion cooling in the respective cylinder/piston unit, isentropic compression in the respective cylinder/piston unit, expansion cooling of fuel/air mixture homogenized in at least one further cylinder/piston unit, external cooling of a fuel/air mixture homogenized in at least one further cylinder/piston unit; and

recirculating the cooled fuel/air mixture into the intake device;

wherein the internal combustion engine includes an inlet valve, the expansion cooling being performed in accordance with one of a late inlet valve opening and an early inlet valve closing.

8. The method according to claim 7, wherein the internal combustion engine further includes an outlet valve, the method further comprising the step of controlling the inlet valve, the outlet valve and the injection system so that by early outlet valve closing during the exhaust stroke, hot exhaust gas is retained in the combustion space, fuel is injected into the hot exhaust gas to generate the homogeneous fuel/air mixture and the homogeneous fuel/air mixture is expansion-cooled by late inlet valve opening during the intake stroke.

9. The method according to claim 8, wherein when a charge-exchange top dead center of a piston of the cylinder/piston unit is defined by a crank angle of 360°

, the combustion process is defined by the following characteristics;

outlet valve opening in a crank angle range between 110° and

140°

;

outlet valve closing in a crank angle range between 270° and

369°

;

inlet valve opening in a crank angle range between 370° and

450°

;

inlet valve closing in a crank angle range between 550° and

570°

; and

injection of fuel between the outlet valve closing and the inlet valve opening.

10. The method according to claim 7, wherein the internal combustion engine further includes an outlet valve and the intake device includes an intake duct, the method further comprising the step of controlling the inlet valve, the outlet valve and the injection system so that during the exhaust stroke, hot exhaust gas from the combustion space is expelled through an open inlet valve into the intake duct, fuel is injected into the hot exhaust gas and fresh intake gas in the intake duct, and, during the intake stroke, the fuel/air mixture is sucked from the intake duct back into the combustion space and is expansion cooled after the early closing of the inlet valve.

11. The method according to claim 10, wherein, when a charge-exchange top dead center of a piston of the cylinder/piston unit is defined by a crank angle of 360°

, the combustion process is defined by the following characteristics;

outlet valve opening in a crank angle range between 110° and

140°

;

outlet valve closing in a crank angle range between 270° and

360°

;

inlet valve opening in a crank angle range between 270° and

360°

;

inlet valve closing in a crank angle range between 460° and

560°

; and

injection of fuel between the inlet valve opening and a crank angle of 5°

before the inlet valve closing.

12. The method according to claim 7, wherein the intake device includes an intake duct, the method further comprising the steps of:

injecting fuel during the exhaust stroke into the combustion space shortly after the closing of the outlet valve and substantially simultaneously therewith;

opening the inlet valve to expel the fuel/exhaust gas mixture formed within the combustion space into the intake duct;

sucking the fuel/exhaust gas mixture with fresh gas through the open inlet valve back into the combustion space during the intake stroke; and

closing the inlet valve simultaneously with the suction of the piston to achieve expansion cooling of the fuel/exhaust gas/fresh gas mixture.

13. The method according to claim 12, wherein, when a charge-exchange top dead center of a piston of the cylinder/piston unit is defined by a crank angle of 360°

, the combustion process is defined by the following characteristics;

outlet valve opening in a crank angle range between 110° and

140°

;

outlet valve closing in a crank angle range between 270° and

360°

;

inlet valve opening in a crank angle range between 270° and

360°

;

inlet valve closing in a crank angle range between 460° and

560° and

injection of fuel between the outlet valve closing and the inlet valve closing.