METHOD FOR OPERATING A SPARK IGNITED ENGINE

• US 20160177851A1
• Filed: 11/02/2015
• Published: 06/23/2016
• Est. Priority Date: 12/19/2014
• Status: Active Grant

• Current Assignee: INNIO Jenbacher GmbH & Co.,OG.
• Original Assignee: GE Jenbacher GmbH & Company OHG (General Electric Company)
• Inventors: GRUBER, Friedrich, SPYRA, Nikolaus, TRAPP, Christian, TINSCHMANN, Georg, MUSU, Ettore, CHRISTINER, Peter
• Granted Patent: US 10,641,190 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F02B 1/02 with positive ignition with non-timed positive ignition F02B9/06
• CPC Class Codes: F02B 19/1085 controlling fuel injection
• CPC Class Codes: F02B 19/12 with positive ignition engines with non-timed positive ignition, and with incandescent chambers F02B9/08
• CPC Class Codes: F02D 19/0642 at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions
• CPC Class Codes: F02D 19/081 Adjusting the fuel composition or mixing ratio; Transitioning from one fuel to the other
• CPC Class Codes: F02D 35/023 by determining the cylinder pressure
• CPC Class Codes: F02D 35/028 by determining the combustion timing or phasing
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/0027 the fuel being gaseous non-electrical control F02D19/02
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• 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 41/0077 Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position EGR valve position sensor F02M26/48
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for operating a spark ignited engine, including forming a combustible mixture by mixing generally homogeneously a first fuel and air and introducing this mixture into the at least one cylinder in an intake stroke, and compressing the combustible mixture with a piston in a compression stroke thereby introducing a part of the combustible mixture into a pre-chamber. During the intake and/or the compression stroke, a second fuel is introduced into the pre-chamber at an introduction-time before start of combustion, and the second fuel is of the same or different chemical composition and/or concentration with respect to the first fuel, and a spark ignites in the prechamber. An amount of second fuel and/or the chemical composition of second fuel introduced to the pre-chamber and/or spark timing of the pre-chamber and/or an in-cylinder charge temperature is chosen such that a desired duration of combustion can be achieved.

Claims

1. A method for operating a spark ignited engine, the engine having at least one cylinder and a piston movable in the at least one cylinder and at least one pre-chamber connected to the at least one cylinder and the method comprising the steps of:

forming a combustible mixture by mixing generally homogeneously a first fuel and air and introducing this mixture into the at least one cylinder in an intake stroke

compressing the combustible mixture with the piston in a compression stroke thereby introducing a part of the combustible mixture into the pre-chamber,

during the intake and/or the compression stroke introducing a second fuel into the pre-chamber at an introduction-time before start of combustion the second fuel being of the same or different chemical composition and/or concentration with respect to the first fuel,

spark igniting in the prechamber,

wherein an amount of second fuel and/or the chemical composition of second fuel introduced to the pre-chamber and/or spark timing of the pre-chamber and/or an in-cylinder charge temperature is being chosen such that a desired duration of combustion can be achieved.

2. Method according to claim 1, wherein the first fuel is natural gas or a mixture of natural gas and CO2 such that the amount of CO2 and CH4 is higher than 80%.

3. Method according to claim 1, wherein the second fuel is natural gas or a combination of natural gas and a gas with H2 higher than 10%.

4. Method according to claim 1, wherein the in-cylinder charge temperature is controlled either by an internal EGR-rate kept in the combustion chamber during gas exchange process, or by an external EGR rate recirculated in the intake system.

5. Method according to claim 1, wherein the in-cylinder charge temperature is controlled by influencing the intake temperature of air and/or first fuel.

6. Method according to claim 1, wherein if the duration of combustion shall be increased the hydrogen amount in the second fuel is decreased, if the duration of combustion shall be decreased the hydrogen amount in the second fuel is increased.

7. Method according to claim 1, wherein if the duration of combustion shall be increased the charge temperature is decreased, if the duration of combustion shall be decreased the charge temperature is increased.

8. Method according to claim 1, wherein spark timing for igniting the prechamber is in a range of 30°

CA BTDC to TDC

9. Method according to claim 8, wherein if the duration of combustion shall be increased the spark timing is retarded, if the duration of combustion shall be decreased the spark timing is advanced.

10. Method according to claim 1, wherein the introduction time of the second fuel is chosen between 400°

to 40°

before firing TDC, a lambda value of larger than 1.6, preferably larger than 1.9, an EGR rate between 0-40%, the amount of second fuel is chosen between 0.5% to 15% with respect to the energy content of the combustible mixture, the mixture temperature at intake of cylinder is chosen between 50-130°

C., preferably between 70-100°

C.

11. Method according to claim 1, wherein the introduction time of the second fuel is chosen between 400°

to 40°

before firing TDC, a lambda value of larger than 2.0, preferably larger than 2.2, an EGR rate between 0-40%, the amount of second fuel is chosen between 0.5% to 15% with respect to the energy content of the combustible mixture, the mixture temperature at intake of cylinder is chosen between 70-130°

C.

12. Method according to claim 1, wherein

a brake mean effective pressure is between 16 and 28 bar,

a compression ratio is between 10 and 14 and,

an intake valve closing at 1 millimeter lift is between 30 degrees before bottom dead center and 30 degrees after bottom dead center during the intake stroke.

13. A spark ignited engine, the engine having at least one cylinder with a prechamber connected to a main chamber and a piston moveable in the at least one cylinder, and a valve to introduce a second fuel into the prechamber, having an electronic control unit configured to operate according to a method according to claim 1.