VARIABLE COMPRESSION RATIO DIESEL ENGINE

• US 20140000567A1
• Filed: 07/02/2013
• Published: 01/02/2014
• Est. Priority Date: 07/02/2012
• Status: Active Grant

• Current Assignee: Pinnacle Engines, Inc.
• Original Assignee: Pinnacle Engines, Inc.
• Inventors: Cleeves, James M.
• Granted Patent: US 9,316,150 B2
• Time in Patent Office: Days
• US Class Current: 123/48.R
• CPC Class Codes: F01B 7/14 acting on different main shafts
• CPC Class Codes: F02B 75/04 Engines with variable distances between pistons at top dead-centre positions and cylinder heads
• CPC Class Codes: F02B 75/047 by means of variable crankshaft position
• CPC Class Codes: F02B 75/28 Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders arranged oppositely relative to main shaft F02B75/24
• CPC Class Codes: F02D 15/02 by alteration or displacement of piston stroke
• CPC Class Codes: F02D 35/026 using an estimation
• 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: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Diesel opposed piston engines, optionally with variable compression ratio and/or turbocharging, can provide improved fuel efficiency by adapting a compression ratio of the engine in accordance with an engine load such that larger compression ratios are used for smaller loads and smaller compression ratios are used for larger loads. Turbocharging can provide improved efficiency at the smaller compression ratio operating conditions. Optionally, one or more current engine parameters can be modified to maintain a peak combustion chamber temperature below a threshold temperature at which an acceptable level of nitrogen oxide pollutants (NO_X) is expected to be formed. One or more swirl inducing features can be included on piston crowns in an opposed piston engine. Methods, systems, articles of manufacture, etc. are described.

Claims

1. A method comprising:

operating a diesel opposed piston engine with a first compression ratio to supply engine power in response to a first engine load, the diesel opposed piston engine comprising a combustion chamber defined at least in part by crowns of two pistons coupled to two crankshafts; and

changing the first compression ratio to a second compression ratio to supply engine power in response to a second engine load, the second engine load being larger than the first engine load, the second compression ratio being smaller than the first compression ratio.

2. A method as in claim 1, wherein the changing of the compression ratio is performed using at least one of a phasing change of the phase of the two pistons and a translation of a distance between the two crankshafts.

3. A method as in claim 1, wherein inlet air is supplied to the combustion chamber via a turbocharger that increases a pressure of the supplied air to higher than ambient pressure.

4. A method as in claim 3, wherein the turbocharger supplies inlet air with a second pressure while the second compression ratio is used and a first pressure while the first compression ratio is used, the second pressure being larger than the first pressure.

5. A method as in claim 1, wherein the crowns of the two pistons comprise one or more swirl canceling features.

6. A method as in claim 5, wherein the one or more swirl canceling features cause inlet air to the combustion chamber to have a high swirl and to split into at least two co-rotating swirls formed in front of respective injectors that deliver fuel to the combustion chamber.

7. A method as in claim 1, further comprising:

determining, based on engine operation information, a predicted peak combustion chamber temperature that will occur in the combustion chamber;

identifying a target set of engine operation parameters when the predicted peak combustion chamber temperature exceeds a threshold temperature at which an acceptable level of nitrogen oxide pollutants (NO_X) is expected to be formed in the combustion chamber; and

applying the target set of engine operation parameters to modify one or more current engine parameters to thereby maintain the peak combustion chamber temperature below the threshold temperature.

8. A method as in claim 7, wherein the engine operation information comprises an intercooler outlet temperature measured at or near an outlet of an intercooler that receives and cools air compressed by a turbocharger, and a compression ratio within the engine.

9. A method as in any of claim 7, wherein the target set of engine parameters comprises fuel delivery parameters.

10. A method as in claim 7, wherein the fuel delivery parameters comprise one or more of an amount of fuel injected into the combustion chamber for a given engine cycle, a timing of one or more injections of fuel during a cycle of the engine, and a number of injections of fuel occurring during the cycle of the engine.

11. A method as in claim 7, wherein the target set of engine parameters comprises a change of a current compression ratio to a smaller compression ratio to reduce an energy density within the combustion chamber and thereby reduce the peak temperature.

12. A diesel opposed piston engine comprising:

a combustion chamber defined at least in part by crowns of two pistons coupled to two crankshafts; and

an engine controller, the engine controller performing operations comprising;

operating the diesel opposed piston engine with a first compression ratio to supply engine power in response to a first engine load; and

changing the first compression ratio to a second compression ratio to supply engine power in response to a second engine load, the second engine load being larger than the first engine load, the second compression ratio being smaller than the first compression ratio.

13. A diesel opposed piston engine as in claim 12, further comprising a compression ratio changing mechanism, the compression ratio changing mechanism comprising at least one of a phaser for changing a phase of the two pistons and a translation mechanism for changing a distance between the two crankshafts.

14. A diesel opposed piston engine as in claim 12, further comprising a turbocharger that increases a pressure of inlet air supplied to the combustion chamber, the turbocharger supplying inlet air with a second pressure while the second compression ratio is used and a first pressure while the first compression ratio is used, the second pressure being larger than the first pressure.

17. A diesel opposed piston engine as in claim 12, wherein the operations performed by the engine controller further comprise:

determining, based on engine operation information, a predicted peak combustion chamber temperature that will occur in the combustion chamber;

identifying a target set of engine operation parameters when the predicted peak combustion chamber temperature exceeds a threshold temperature at which an acceptable level of nitrogen oxide pollutants (NO_X) is expected to be formed in the combustion chamber; and

applying the target set of engine operation parameters to modify one or more current engine parameters to thereby maintain the peak combustion chamber temperature below the threshold temperature.

15. A diesel opposed piston engine as in 12, wherein the crowns of the two pistons comprise one or more swirl canceling features.

16. A diesel opposed piston engine as in claim 15, wherein the one or more swirl canceling features cause inlet air to the combustion chamber to have a high swirl and to split into at least two co-rotating swirls formed in front of respective injectors that deliver fuel to the combustion chamber.

18. A diesel opposed piston engine comprising:

a combustion chamber defined at least in part by crowns of two pistons coupled to two crankshafts; and

an engine controller, the engine controller performing operations comprising;

determining, based on engine operation information, a predicted peak combustion chamber temperature that will occur in the combustion chamber;

identifying a target set of engine operation parameters when the predicted peak combustion chamber temperature exceeds a threshold temperature at which an acceptable level of nitrogen oxide pollutants (NO_X) is expected to be formed in the combustion chamber; and

applying the target set of engine operation parameters to modify one or more current engine parameters to thereby maintain the peak combustion chamber temperature below the threshold temperature.

19. A diesel opposed piston engine as in claim 18, wherein:

the engine operation information comprises an intercooler outlet temperature measured at or near an outlet of an intercooler that receives and cools air compressed by a turbocharger, and a compression ratio within the engine; and

the target set of engine parameters comprises at least one of fuel delivery parameters, a change of a current compression ratio to a smaller compression ratio to reduce an energy density within the combustion chamber and thereby reduce the peak temperature.

20. A diesel opposed piston engine as in claim 18, wherein the fuel delivery parameters comprise one or more of an amount of fuel injected into the combustion chamber for a given engine cycle, a timing of one or more injections of fuel during a cycle of the engine, and a number of injections of fuel occurring during the cycle of the engine.