Air-cooled, four-stroke aviation engine

Patent metadata

Field	Value
Publication number	US-12012910-B2
Application number	US-202217873705-A
Country	US
Kind code	B2
Filing date	Jul 26, 2022
Priority date	Jul 27, 2021
Publication date	Jun 18, 2024
Grant date	Jun 18, 2024

Abstract

An improved air-cooled aviation engine includes a compact combustion chamber having an intake valve opening, an exhaust valve opening, and a generally elliptical shape. The elliptical shape has a major axis and a minor axis, with the major axis intersecting both the intake valve opening and the exhaust valve opening. In some examples, the major axis is the same length or shorter than a diameter of a cylinder bore of the engine, and the minor axis is smaller than the major axis. Combustion is thus constrained to a smaller area than that of the cylinder bore.

First claim

What is claimed is:

1. An air-cooled aviation engine, comprising:
a cylinder head having an intake valve opening, an exhaust valve opening, a plurality of spark plugs, and an interior surface;
a cylinder bore having a cross-sectional area and containing a piston configured to move reciprocally within the cylinder bore;
a combustion chamber having an upper region defined by the interior surface of the cylinder head and a lower region defined by the piston when the piston is in an uppermost position within the cylinder bore;
an intake valve arranged to selectively admit intake air into the combustion chamber via the intake valve opening, the intake valve having an intake valve stem and an intake valve head; and
an exhaust valve arranged to selectively allow exhaust gases to be expelled from the combustion chamber via the exhaust valve opening, the exhaust valve having an exhaust valve stem and an exhaust valve head,
wherein the combustion chamber has an elliptical shape that extends over a cross-sectional area smaller than the cross-sectional area of the cylinder bore, the elliptical shape having a major axis that intersects the intake valve opening and the exhaust valve opening,
wherein each of the intake valve stem and the exhaust valve stem includes a triple-bead attachment to a respective valve retainer, each triple-bead attachment constructed and arranged to facilitate rotation of a respective valve within the respective valve retainer, and
wherein the air-cooled aviation engine further comprises:
a first spring disposed between an intake valve retainer and a first spring seat of the cylinder head, the first spring being constructed and arranged to incrementally rotate the intake valve within an intake valve retainer on successive compressions of the first spring; and
a second spring disposed between an exhaust valve retainer and a second spring seat of the cylinder head, the second spring being constructed and arranged to incrementally rotate the exhaust valve within an exhaust valve retainer on successive compressions of the second spring.

2. The air-cooled aviation engine of claim 1 , wherein the cylinder head has a flat shoulder region that abuts a flat outer region of the piston when the piston is in the uppermost position within the cylinder bore, and wherein the flat shoulder region and the flat outer region constrain the combustion chamber to the elliptical shape.

3. The air-cooled aviation engine of claim 2 , wherein each of the plurality of spark plugs includes respective electrodes, and wherein the electrodes of the plurality of spark plugs extend below the interior surface of the combustion chamber.

4. The air-cooled aviation engine of claim 3 , wherein the electrodes of the plurality of spark plugs are disposed closer to the exhaust valve opening than to the intake valve opening.

5. The air-cooled aviation engine of claim 3 , wherein the cylinder bore has a center line and a radius, and wherein the electrodes of the plurality of spark plugs are disposed at respective distances from the center line that are less than 65% of the radius of the cylinder bore.

6. The air-cooled aviation engine of claim 3 , further comprising a high-tumble intake port coextensive with the intake valve opening of the cylinder head, the high-tumble intake port constructed and arranged to induce vertical currents within the combustion chamber.

7. The air-cooled aviation engine of claim 3 , wherein the piston includes a depression beneath the electrodes of each of the plurality of spark plugs, and wherein at least a portion of the piston is elevated relative to the depression.

8. The air-cooled aviation engine of claim 7 , wherein the depression is a single depression that extends completely around a top surface of the piston with the elevated portion disposed at a center thereof.

9. The air-cooled aviation engine of claim 7 , wherein the depression includes respective independent depressed portions formed below the electrodes of the plurality of spark plugs.

10. The air-cooled aviation engine of claim 1 , wherein the cylinder head further includes:
an intake valve seat that fits within the intake opening; and
an exhaust valve seat that fits within the exhaust opening.

11. The air-cooled aviation engine of claim 10 , wherein the intake valve seat and the exhaust valve seat are each composed at least in part of copper-infiltrated powdered metal and/or solid alloy that includes copper.

12. The air-cooled aviation engine of claim 10 , wherein the intake valve seat and the exhaust valve seat each have a respective inner region, each inner region having multiple discretely angled surfaces.

13. The air-cooled aviation engine of claim 10 , wherein the intake valve stem has a diameter of less than 9 mm, and wherein the exhaust valve stem has a diameter of less than 9 mm.

14. The air-cooled aviation engine of claim 10 , wherein the intake valve head and the exhaust valve head have multiple discretely-angled surfaces adjacent to contact regions with the respective valve seats.

15. The air-cooled aviation engine of claim 10 , wherein the cylinder head includes an exhaust valve-stem guide around the exhaust valve stem, the exhaust valve-stem guide composed at least in part of copper and produced as a powdered metal and/or solid alloy.

16. The air-cooled aviation engine of claim 1 , wherein the triple-bead attachment for each valve stem includes a triple-bead key that engages triple-bead grooves in the valve stem, the triple-bead key being attached to the respective valve retainer.

17. The air-cooled aviation engine of claim 16 , wherein the triple-bead key is wedged into the respective valve retainer.

18. The air-cooled aviation engine of claim 1 , further comprising:
a first rocker arranged to move the intake valve head away from intake valve opening and actuate the first spring; and
a second rocker arranged to move the exhaust valve head away from the exhaust valve opening and actuate the second spring,
wherein both the first spring and the second spring are further arranged to rotate upon being actuated.

19. The air-cooled aviation engine of claim 1 , wherein the second spring is further constructed and arranged to incrementally rotate the exhaust valve head on successive compressions of the second spring to remove deposits formed between the exhaust valve head and the exhaust valve opening.

20. An air-cooled aviation engine, comprising multiple cylinders, each cylinder including:
a cylinder head having an intake valve opening, an exhaust valve opening, a plurality of spark plugs, and an interior surface;
a cylinder bore having a cross-sectional area and containing a piston configured to move reciprocally within the cylinder bore; and
a combustion chamber having an upper region defined by the interior surface of the cylinder head and a lower region defined by the piston when the piston is in an uppermost position within the cylinder bore;
an intake valve arranged to selectively admit intake air into the combustion chamber via the intake valve opening, the intake valve having an intake valve stem and an intake valve head; and
an exhaust valve arranged to selectively allow exhaust gases to be expelled from the combustion chamber via the exhaust valve opening, the exhaust valve having an exhaust valve stem and an exhaust valve head,
wherein the combustion chamber has an elliptical shape that extends over a cross-sectional area smaller than the cross-sectional area of the cylinder bore, the elliptical shape having a major a

Assignees

• Textron Innovations Inc

Inventors

• Baer Patrick Henry
• Glucksman Michael Glynn

Classifications

• F02F1/4235

  of intake channels · CPC title

• F02F1/28

  for air cooling · CPC title

• F01L3/08

  Valves guides; Sealing of valve stem, e.g. sealing by lubricant · CPC title

• F01L3/02

  Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials · CPC title

• B64D27/04

  of piston type · CPC title