Dual fuel engine which ignites a homogeneous mixture of gaseous fuel, air, and pilot fuel

• US 6,032,617 A
• Filed: 05/27/1998
• Issued: 03/07/2000
• Est. Priority Date: 05/27/1998
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Willi, Martin L., Wu, Min
• Primary Examiner(s): Argenbright, Tony M.
• Assistant Examiner(s): Hairston, Brian J.
• Application Number:
  US09/085,641
• Time in Patent Office: 650 Days
• Field of Search: 123/299, 123/300, 123/304, 123/27 GE, 123/435, 123/525, 123/526, 123/431, 123/25 C
• US Class Current: 123/27.0GE
• CPC Class Codes: F02B 2201/064 Liquid and gas
• CPC Class Codes: F02B 43/00 Engines characterised by operating on gaseous fuels; Plants including such engines engines characterised by the gas-air charge being ignited by compression ignition of an additional fuel F02B7/06; engines convertible from gas to other fuel consumption F02B69/04
• CPC Class Codes: F02D 19/061 by controlling fuel injectors
• 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 19/0657 Heavy or light fuel oils; Fuels characterised by their impurities such as sulfur content or differences in grade, e.g. for ships
• CPC Class Codes: F02D 19/0692 Arrangement of multiple injectors per combustion chamber
• CPC Class Codes: F02D 19/10 peculiar to compression-ignition engines in which the main fuel is gaseous
• CPC Class Codes: F02M 25/0228 Adding fuel and water emulsion
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A method of operating an engine assembly having a cylinder assembly which defines a combustion chamber is disclosed. The method includes the steps of performing an intake stroke of the cylinder assembly and advancing a conditioning fuel into the combustion chamber during the intake stroke performing step. The method further includes the steps of advancing a gaseous fuel into the combustion chamber during the intake stroke performing step and performing a compression stroke of the cylinder assembly after the intake stroke performing step. The method yet further includes the steps of advancing a pilot fuel into the combustion chamber during the compression stroke performing step and combusting the pilot fuel in the combustion chamber during the compression stroke performing step so as to ignite the conditioning fuel and the gaseous fuel. The gaseous fuel and the conditioning fuel are mixed in the combustion chamber prior to the pilot fuel advancing step so as to facilitate ignition of the gaseous fuel in the combustion chamber.

Claims

1. A method of operating an engine assembly having a cylinder assembly which defines a combustion chamber, comprising the steps of:

performing an intake stroke of the cylinder assembly;

advancing a conditioning fuel into the combustion chamber during the intake stroke performing step;

advancing a gaseous fuel into the combustion chamber during the intake stroke performing step;

performing a compression stroke of the cylinder assembly after the intake stroke performing step;

advancing a pilot fuel into the combustion chamber during the compression stroke performing step; and

combusting the pilot fuel in the combustion chamber during the compression stroke performing step so as to ignite the conditioning fuel and the gaseous fuel,

whereby the gaseous fuel and the conditioning fuel are mixed in the combustion chamber prior to the pilot fuel advancing step so as to facilitate ignition of the gaseous fuel in the combustion chamber.

2. The method of claim 1, wherein:

the engine assembly further includes a fuel injector,

the conditioning fuel advancing step includes the step of operating the fuel injector to advance the conditioning fuel into the combustion chamber, and

the pilot fuel advancing step includes the step of operating the fuel injector to advance the pilot fuel into the combustion chamber.

3. The method of claim 2, wherein:

the cylinder assembly includes an engine head,

the engine head includes an injector opening defined therein,

the fuel injector is positioned to inject pilot fuel through the injector opening, and

the pilot fuel advancing step includes the step of injecting pilot fuel into the combustion chamber through the injector opening.

4. The method of claim 2, wherein:

the conditioning fuel is diesel fuel, and

the pilot fuel is diesel fuel.

5. The method of claim 1, wherein:

the engine assembly further includes a pressure sensor positioned to measure pressure in the combustion chamber, and

the conditioning fuel advancing step further includes the steps of (i) measuring the pressure in the combustion chamber during the compression stroke so as to obtain a number of measured pressure values, and (ii) adjusting the amount of conditioning fuel advanced to the combustion chamber during a subsequent intake stroke based on the measured pressure values.

6. The method of claim 1, wherein:

the engine assembly further includes a pressure sensor positioned to measure pressure in the combustion chamber, and

the pilot fuel advancing step further includes the steps of (i) measuring the pressure in the combustion chamber during the compression stroke so as to obtain a number of measured pressure values, and (ii) adjusting the amount of pilot fuel advanced into the combustion chamber during a subsequent compression stroke based on the measured pressure values.

7. The method of claim 1, wherein:

the engine assembly further includes a pressure sensor positioned to measure pressure in the combustion chamber, and

the pilot fuel advancing step further includes the steps of (i) measuring the pre sure in the combustion chamber during the compression stroke so as to obtain a number of measured pressure values, and (ii) adjusting when the pilot fuel is advanced into the combustion chamber during the compression stroke based on the measured pressure values.

8. The method of claim 1, wherein:

the engine assembly further includes a first fuel injector and a second fuel injector,

the pilot fuel advancing step includes the step of operating the first fuel injector to advance the pilot fuel into the combustion chamber, and

the conditioning fuel advancing step includes the step of operating the second injector to advance the conditioning fuel into the combustion chamber.

9. The method of claim 8, wherein:

the cylinder assembly includes an engine head,

the engine head includes a first injector opening defined therein,

the first fuel injector is positioned to inject pilot fuel through the first injector opening, and

the pilot fuel advancing step further includes the step of injecting pilot fuel into the combustion chamber through the first injector opening.

10. The method of claim 8, wherein:

the engine assembly further includes an intake conduit which is in fluid communication with the combustion chamber,

the intake conduit includes a second injector opening defined in a side wall thereof,

the second fuel injector is positioned to inject conditioning fuel through the second injector opening, and

the conditioning fuel advancing step includes the step of injecting conditioning fuel into the intake conduit through the second injector opening.

11. The method of claim 10, wherein:

the conditioning fuel is selected from the group consisting essentially of (i) a lubricating oil, (ii) a crude oil, and (iii) an emulsion of H₂ O and diesel fuel, and

the pilot fuel is diesel fuel.

12. A method of operating an engine assembly having a cylinder assembly which defines a combustion chamber, with the cylinder assembly being operable to perform an intake stroke and a compression stroke, comprising the steps of:

advancing a conditioning fuel into the combustion chamber with a fuel injector during the intake stroke;

advancing a gaseous fuel into the combustion chamber during the intake stroke;

advancing a pilot fuel into the combustion chamber with the fuel injector during the compression stroke; and

combusting the pilot fuel in the combustion chamber during the compression stroke so as to ignite the conditioning fuel and the gaseous fuel.

13. The method of claim 12, wherein:

the cylinder assembly includes an engine head,

the engine head includes an injector opening defined therein,

the fuel injector is positioned to inject pilot fuel through the injector opening, and

the pilot fuel advancing step includes the step of injecting pilot fuel into the combustion chamber through the injector opening.

14. The method of claim 12, wherein:

the conditioning fuel is diesel fuel, and

the pilot fuel is diesel fuel.

15. The method of claim 12, wherein:

the engine assembly further includes a pressure sensor positioned to measure pressure in the combustion chamber,

the pilot fuel advancing step further includes the step of measuring the pressure in the combustion chamber during the compression stroke so as to obtain a number of measured pressure values,

the conditioning fuel advancing step further includes the step of adjusting the amount of conditioning fuel advanced to the combustion chamber during a subsequent intake stroke based on the measured pressure values, and

the pilot fuel advancing step further includes the steps of (i) adjusting the amount of pilot fuel advanced to the combustion chamber during a subsequent compression stroke based on the measured pressure values and (ii) adjusting when the pilot fuel is advanced into the combustion chamber during the subsequent compression stroke based on the measured pressure values.

16. A method of operating an engine assembly having a cylinder assembly which defines a combustion chamber, with the cylinder assembly being operable to perform an intake stroke and a compression stroke, comprising the steps of:

advancing a conditioning fuel into the combustion chamber with a conditioning fuel injector during the intake stroke;

advancing a gaseous fuel into the combustion chamber during the intake stroke;

advancing a pilot fuel into the combustion chamber with a pilot fuel injector during the compression stroke; and

combusting the pilot fuel in the combustion chamber during the compression stroke so as to ignite the conditioning fuel and the gaseous fuel.

17. The method of claim 16, wherein:

the engine assembly further includes an intake conduit which is in fluid communication with the combustion chamber,

the intake conduit includes a conditioning injector opening defined in a side wall thereof,

the conditioning fuel injector is positioned to inject conditioning fuel through the second injector opening, and

the conditioning fuel advancing step includes the step of injecting conditioning fuel into the intake conduit through the conditioning injector opening.

18. The method of claim 17, wherein:

the cylinder assembly includes an engine head,

the engine head includes a pilot injector opening defined therein,

the pilot fuel injector is positioned to inject pilot fuel through the pilot injector opening, and

the pilot fuel advancing step includes the step of injecting pilot fuel into the combustion chamber through the pilot injector opening.

19. The method of claim 18, wherein:

the conditioning fuel is selected from the group consisting essentially of (i) a lubricating oil, (ii) a crude oil, and (iii) an emulsion of H₂ O and diesel fuel, and

the pilot fuel is diesel fuel.

20. The method of claim 16, wherein:

the engine assembly further includes a pressure sensor positioned to measure pressure in the combustion chamber,

the pilot fuel advancing step further includes the step of measuring the pressure in the combustion chamber during the compression stroke so as to obtain a number of measured pressure values,

the conditioning fuel advancing step further includes the step of adjusting the amount of conditioning fuel advanced to the combustion chamber during the subsequent intake stroke based on the measured pressure values, and

the pilot fuel advancing step further includes the steps of (i) adjusting the amount of pilot fuel advanced to the combustion chamber during a subsequent compression stroke based on the measured pressure values and (ii) adjusting when the pilot fuel is advanced to the combustion chamber during a subsequent compression stroke based on the measured pressure values.