Rotary internal combustion engine with pilot subchamber

Patent metadata

Field	Value
Publication number	US-10557407-B2
Application number	US-201715825683-A
Country	US
Kind code	B2
Filing date	Nov 29, 2017
Priority date	Jul 28, 2011
Publication date	Feb 11, 2020
Grant date	Feb 11, 2020

Abstract

A rotary engine including a rotor sealingly received within an internal cavity of an outer body to define a plurality of combustion chambers having a variable volume, a pilot subchamber located in a wall of the outer body, the pilot subchamber in fluid communication with the internal cavity via at least two spaced apart transfer holes defining a flow restriction between the pilot subchamber and the internal cavity, a pilot fuel injector in fluid communication with the pilot subchamber, an ignition element configured for igniting fuel in the pilot subchamber, and a main fuel injector extending through the stator body and communicating with the cavity at a location spaced apart from the pilot subchamber. A method of combusting fuel in a rotary engine is also discussed.

First claim

The invention claimed is:

1. A rotary engine comprising:
a rotor sealingly received within an internal cavity of an outer body to define a plurality of combustion chambers;
a pilot subchamber located in a wall of the outer body, the pilot subchamber in fluid communication with the internal cavity via at least two spaced apart transfer holes defining a flow restriction between the pilot subchamber and the internal cavity, the pilot subchamber in use in fluid communication with the combustion chambers as the rotor rotates;
a pilot fuel injector in fluid communication with the pilot subchamber;
an ignition element configured for igniting fuel in the pilot subchamber;
a main fuel injector communicating with the internal cavity independently from the pilot subchamber; and
wherein the pilot subchamber has a volume corresponding to from 5% to 25% of a sum of a minimum volume of one of the combustion chambers and the volume of the pilot subchamber.

2. The engine as defined in claim 1 , wherein an insert is received in a peripheral wall of the stator body, the insert being made of a material having a greater heat resistance than that of the peripheral wall, the insert having the pilot subchamber defined therein, the at least two transfer holes extending through the insert.

3. The engine as defined in claim 2 , wherein the insert is made of ceramic or super alloy.

4. The engine as defined in claim 2 , wherein the ignition element is received within an ignition element hole defined through the insert.

5. The engine as defined in claim 2 , wherein the pilot injector extends through the peripheral wall at a non-zero angle with respect to a surface of an outer wall of the insert with only a portion thereof extending within the insert.

6. The engine as defined in claim 2 , wherein the pilot injector extends through the peripheral wall at a non-zero angle with respect to a longitudinal direction of the insert.

7. The engine as defined in claim 1 , wherein the volume of the pilot subchamber corresponds to from 10% to 12% of the sum of the minimum volume and the volume of the pilot subchamber.

8. The engine as defined in claim 1 , wherein a difference between a maximum volume and a minimum volume of one of the combustion chambers defines a displacement volume, the subchamber having a volume of at least about 0.5% of the displacement volume and at most about 3.5% of the displacement volume.

9. The engine as defined in claim 1 , wherein a difference between a maximum volume and a minimum volume of one of the combustion chambers defines a displacement volume, the pilot subchamber having a volume of at least 0.625% of the displacement volume.

10. The engine as defined in claim 1 , wherein a difference between a maximum volume and a minimum volume of one of the combustion chambers defines a displacement volume, the pilot subchamber having a volume of about 1.25% of the displacement volume.

11. The engine as defined in claim 1 , further comprising a heavy fuel source in communication with the main and pilot fuel injectors.

12. The engine as defined in claim 1 , wherein the ignition element is a glow plug.

13. The rotary engine as defined in claim 1 , wherein the rotary engine is a Wankel engine, the outer body including a peripheral wall cooperating with two spaced apart end walls to define the internal cavity, the peripheral wall defining two lobes, the rotor having three circumferentially-spaced apex portions in sealing engagement with the peripheral wall and separating the combustion chambers.

14. A compound engine assembly including the rotary engine as defined in claim 1 , a compressor in fluid communication with the intake port of the rotary engine, and a turbine in fluid communication with the exhaust port of the rotary engine, the turbine having a turbine shaft compounded with an engine shaft drivingly engaged to the rotor.

15. The engine as defined in claim 1 , wherein each of the at least two spaced apart transfer holes having a central axis located outside a periphery of each of the others of the at least two spaced apart transfer holes.

16. A method of combusting fuel in a rotary engine, the method comprising:
injecting a minor portion of the fuel into a pilot subchamber;
injecting a major portion of the fuel into a combustion chamber of the rotary engine independently of the pilot subchamber;
igniting the fuel within the pilot subchamber;

igniting the fuel in the combustion chamber by directing the ignited fuel from the pilot subchamber into the combustion chamber in at least two discrete flows; and
wherein the pilot subchamber has a volume corresponding to from 5% to 25% of a sum of a minimum volume of the combustion chamber and the volume of the pilot subchamber volume.

17. The method as defined in claim 16 , wherein the volume of the pilot subchamber corresponds to from 10% to 12% of the sum of the minimum volume and the volume of the pilot subchamber.

18. The method as defined in claim 16 , further comprising creating a hot wall around the pilot subchamber by providing the pilot subchamber in an insert received in a wall of a stator of the engine, the insert being made of a material more resistant to high temperature than that of the wall.

19. The method as defined in claim 18 , wherein the insert is received in a peripheral wall of the engine.

20. The method as defined in claim 18 , wherein the insert is made of ceramic or super alloy.

21. The method as defined in claim 18 , wherein injecting the minor portion of the fuel into the pilot subchamber includes injecting from 0.5 to 20% of the fuel.

22. The method as defined in claim 16 , wherein injecting the minor portion of the fuel into the pilot subchamber includes injecting from 5 to 10% of the fuel.

23. The method as defined in claim 16 , wherein injecting the minor portion of the fuel is done in an angled direction with respect to a central transverse axis of a stator of the engine.

24. The method as defined in claim 16 , wherein the fuel is heavy fuel.

25. The method as defined in claim 16 , wherein the rotary engine is a Wankel engine and the combustion chamber is one of three combustion chambers, the engine having a housing including a peripheral wall cooperating with two spaced apart end walls to define an internal cavity, the peripheral wall defining two lobes, and having a rotor including three circumferentially-spaced apex portions in sealing engagement with the peripheral wall and separating the three combustion chambers.

26. The method as defined in claim 16 , wherein directing the ignited fuel from the pilot subchamber into the combustion chamber in at least two discrete flows is via at least two spaced apart transfer holes, each of the at least two spaced apart transfer holes having a central axis located outside a periphery of each of the others of the at least two spaced apart transfer holes.

Assignees

• Pratt & Whitney Canada

Inventors

• Dussault Serge
• Julien Andre
• Lanktree Michael
• Schulz Edwin
• Thomassin Jean
• Davenport Nigel
• Gekht Eugene

Classifications

• F02B19/14

  with compression ignition · CPC title

• F02B19/108

  with fuel injection at least into pre-combustion chamber, i.e. injector mounted directly in the pre-combustion chamber · CPC title

• F02B19/12

  with positive ignition (engines with non-timed positive ignition, and with incandescent chambers F02B9/08) · CPC title

• F01C21/106

  with a radial surface, e.g. cam rings · CPC title

• F02B55/08 Primary

  Outer members for co-operation with rotary pistons; Casings · CPC title