ROTARY INTERNAL COMBUSTION ENGINE WITH PILOT SUBCHAMBER

• US 20130025567A1
• Filed: 10/14/2011
• Published: 01/31/2013
• Est. Priority Date: 07/28/2011
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Gekht, Eugene, THOMASSIN, Jean, Davenport, Nigel
• Granted Patent: US 9,038,594 B2
• Time in Patent Office: Days
• US Class Current: 123/209
• CPC Class Codes: F01C 1/22 of internal-axis type with equidirectional movement of co-operating members at the points of engagement, or with one of the co-operating members being stationary, the inner member having more teeth or tooth- equivalents than the outer member
• CPC Class Codes: F01C 11/006 of dissimilar working principle
• CPC Class Codes: F01C 20/06 specially adapted for stopping, starting, idling or no-load operation
• CPC Class Codes: F01C 20/10 characterised by changing the positions of the inlet or outlet openings with respect to the working chamber
• CPC Class Codes: F01C 20/24 characterised by using valves for controlling pressure or flow rate, e.g. discharge valves F01C20/10 takes precedence
• CPC Class Codes: F01C 21/06 Heating; Cooling of machines or engines in general F01P; Heat insulation heat insulation in general F16L
• CPC Class Codes: F01C 21/08 Rotary pistons reciprocating pistons in general F16J
• CPC Class Codes: F01C 21/106 with a radial surface, e.g. cam rings
• CPC Class Codes: F01C 21/18 Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
• CPC Class Codes: F01C 21/183 Arrangements for supercharging the working space similar arrangements for internal combustion engines F02B33/00, F02B27/00
• CPC Class Codes: F02B 19/10 with fuel introduced partly into pre-combustion chamber, and partly into cylinder
• CPC Class Codes: F02B 19/12 with positive ignition engines with non-timed positive ignition, and with incandescent chambers F02B9/08
• CPC Class Codes: F02B 53/02 Methods of operating
• CPC Class Codes: F02B 53/10 Fuel supply; Introducing fuel to combustion space
• CPC Class Codes: F02B 53/12 Ignition
• CPC Class Codes: F02B 55/08 Outer members for co-operation with rotary pistons; Casings
• CPC Class Codes: F04C 2240/80 Other components
• CPC Class Codes: F04C 29/0092 Removing solid or liquid contaminants from the gas under pumping, e.g. by filtering or deposition; Purging; Scrubbing; Cleaning
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A Wankel engine system having an insert in the peripheral wall of the rotor body, the insert being made of a material having a greater heat resistance than that of the peripheral wall, having a subchamber defined therein and having an inner surface bordering the cavity, the subchamber communicating with the cavity through at least one opening defined in the inner surface and having a shape forming a reduced cross-section adjacent the opening, a pilot fuel injector having a tip received in the subchamber, an ignition element having a tip received in the subchamber, and a main fuel injector extending through the housing and having a tip communicating with the cavity at a location spaced apart from the insert.

Claims

1. A rotary engine comprising:

a stator body having an internal cavity defined by two axially spaced apart end walls and a peripheral wall extending between the end walls, the cavity having an epitrochoid shape defining two lobes;

a rotor body having three circumferentially spaced apex portions, the rotor body being engaged to an eccentric portion of a shaft to rotate and perform orbital revolutions within the cavity with each of the apex portions remaining in sealing engagement with the peripheral wall and separating three rotating chambers of variable volume defined in the cavity around the rotor body;

an insert in the peripheral wall of the rotor body, the insert being made of a material having a greater heat resistance than that of the peripheral wall, the insert having a subchamber defined therein and having an inner surface bordering the cavity, the subchamber communicating with the cavity through at least one opening defined in the inner surface and having a shape forming a reduced cross-section adjacent the opening;

a pilot fuel injector having a tip received in the subchamber;

an ignition element having a tip received in the subchamber; and

a main fuel injector extending through the housing and having a tip communicating with the cavity at a location spaced apart from the insert.

2. The engine as defined in claim 1, wherein the volume of each chamber varies between a minimum volume and a maximum volume with a difference between the maximum volume and the minimum volume defining 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.

3. The engine as defined in claim 2, wherein the subchamber has a volume of at least 0.625% of the displacement volume.

4. The engine as defined in claim 2, wherein the subchamber has a volume of about 1.25% the displacement volume.

5. The engine as defined in claim 1, wherein the volume of each chamber varies between a minimum volume and a maximum volume, the subchamber having a volume corresponding to from 5% to 25% of a sum of the minimum volume and the volume of the subchamber.

6. The engine as defined in claim 4, wherein the volume of the subchamber corresponds to from 10% to 12% of the sum of the minimum volume and the volume of the subchamber.

7. The engine as defined in claim 1, wherein the insert is made of ceramic or super alloy.

8. The engine as defined in claim 1, wherein the pilot injector extends through the peripheral wall at an angle with respect to the insert with only a portion thereof extending within the insert.

9. The engine as defined in claim 1, further comprising a heavy fuel source in communication with the fuel injectors.

10. A stator body for a Wankel engine comprising:

two axially spaced apart end walls;

a peripheral wall extending between the end walls and defining an internal cavity therewith, the cavity having an epitrochoid shape defining two lobes;

an insert in the peripheral wall of the rotor body, the insert being made of a material having a greater heat resistance than that of the peripheral wall, the insert having a subchamber defined therein and having an inner surface bordering the cavity, the subchamber communicating with the cavity through at least one opening defined in the inner surface and having a shape forming a reduced cross-section adjacent the opening;

at least one of the insert and the peripheral wall having a pilot fuel injector elongated hole defined therethrough communicating with the subchamber and sized to receive a pilot fuel injector therein;

at least one of the insert and the peripheral wall having an ignition element elongated hole defined therethrough communicating with the subchamber and sized to receive an ignition element therein; and

the peripheral wall having a main fuel injector elongated hole defined therethrough spaced apart from the insert and sized to receive a main fuel injector therein.

11. The stator body as defined in claim 10, wherein the insert is made of ceramic or super alloy.

12. The stator body as defined in claim 10, wherein the peripheral wall has a major part of the pilot fuel injector elongated hole defined therethrough.

13. The stator body as defined in claim 10, wherein only the insert has the ignition element elongated hole defined therethrough.

14. A method of injecting heavy fuel into a Wankel engine having rotating chambers each having a volume varying between a minimum volume and a maximum volume, the method comprising:

injecting a minor portion of the heavy fuel into a subchamber defined adjacent to and in sequential communication with each of the rotating chambers and having a subchamber volume corresponding to from 5% to 25% of a sum of the minimum volume and the subchamber volume;

igniting the heavy fuel within the subchamber;

partially restricting a flow of the ignited heavy fuel from the subchamber to the rotating chambers; and

injecting a remainder of the heavy fuel into each of the rotating chambers sequentially, independently of and spaced apart from the subchamber.

15. The method as defined in claim 14, wherein injecting a minor portion of the heavy fuel into the subchamber includes injecting from 0.5% to 20% of the heavy fuel.

16. The method as defined in claim 14, wherein injecting a minor portion of the heavy fuel into the subchamber includes injecting from 5% to 10% of the heavy fuel.

17. The method as defined in claim 14, wherein injecting the minor portion of the heavy fuel is done into the subchamber with the subchamber volume corresponding to from 10% to 12% of the sum of the minimum volume and the subchamber volume.

18. The method as defined in claim 14, wherein injecting the minor portion of the heavy fuel is done through an insert in a peripheral wall of the engine, with the subchamber being defined within the insert.

19. The method as defined in claim 14, wherein injecting the minor portion of the heavy fuel is done in an angled direction with respect to a central transverse axis of a stator of the engine.

20. The method as defined in claim 14, further comprising helping combustion with a hot wall around the subchamber by providing the subchamber in an insert made of a material more resistant to high temperature that a remainder of a stator of the engine.