INTERNAL COMBUSTION ENGINES

• US 20100192923A1
• Filed: 05/28/2008
• Published: 08/05/2010
• Est. Priority Date: 06/06/2007
• Status: Active Grant

• Current Assignee: Cox Powertrain Ltd
• Original Assignee: Cox Powertrain Ltd
• Inventors: Cox, David
• Granted Patent: US 8,499,726 B2
• Time in Patent Office: Days
• US Class Current: 123/51.0BC
• CPC Class Codes: F01B 1/08 with cylinders arranged oppositely relative to main shaft and of "flat" type
• CPC Class Codes: F01B 7/04 acting on same main shaft
• CPC Class Codes: F01B 7/10 having piston-rod of one piston passed through other piston
• CPC Class Codes: F01B 9/023 of Bourke-type or Scotch yoke
• CPC Class Codes: F02B 2075/025 two
• CPC Class Codes: F02B 2075/1808 two
• CPC Class Codes: F02B 2275/40 Squish effect
• CPC Class Codes: F02B 25/08 Engines with oppositely-moving reciprocating working pistons
• CPC Class Codes: F02B 75/24 with cylinders arranged oppositely relative to main shaft and of "flat" type
• 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: F02F 1/22 characterised by having ports in cylinder wall for scavenging or charging
• CPC Class Codes: F02F 3/0015 Multi-part pistons
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

The invention provides a 2-stroke internal combustion engine comprising two opposed cylinders, each cylinder housing two opposed pistons and having at least one exhaust port and at least one intake port, and a crankshaft having asymmetrically arranged journals and scotch-yoke mechanisms for driving the journals from the pistons. The pistons in each cylinder operate to open its exhaust port or ports before its intake port or ports and to close its exhaust port or ports before its intake port or ports.

Claims

1. A 2-stroke internal combustion engine comprising:

two opposed cylinders, each cylinder housing two opposed pistons and having at least one exhaust port and at least one intake port; and

a crankshaft having asymmetrically arranged journals and scotch-yoke mechanisms for driving the journals from the pistons,

wherein, the pistons in each cylinder operate to open its exhaust port or ports before its intake port or ports and to close its exhaust port or ports before its intake port or ports.

2. An engine according to claim 1, wherein the geometric configurations and the masses of the pistons are selected so as to minimize the dynamic imbalance of the engine during its operation.

3. A 2-stroke internal combustion engine comprising:

a crankshaft having a plurality of journals;

two opposed cylinders having their inner ends adjacent to the crankshaft, each cylinder having inner and outer pistons reciprocatably disposed therein and forming a combustion chamber therebetween;

first and second scotch-yoke mechanisms, rigidly attached to the inner pistons, which, acting in unison, drivingly couple the inner pistons to their corresponding journals on the crankshaft; and

a third scotch-yoke mechanism, rigidly attached to the outer pistons, which drivingly couples the outer pistons to their corresponding journal on the crankshaft.

4. An engine according to claim 3, wherein the geometric configurations of the pistons and scotch-yoke mechanisms are selected so as to minimize the dynamic imbalance of the engine during its operation.

5. An engine according to claim 3, wherein the third scotch-yoke mechanism is rigidly attached to the outer pistons via rods passing through holes in the combustion faces of the inner pistons.

6. An engine according to claim 3, wherein the product of the effective mass of a first system comprising the outer pistons and the third scotch-yoke multiplied by the throw of the associated crankshaft journal is essentially equal to the product of the effective mass of a second system comprising the inner pistons and first and second scotch-yokes multiplied by the throw of the associated crankshaft journals, so that the dynamic imbalance due to the first system essentially cancels the dynamic imbalance due to the second system.

7. An engine according to claim 3, wherein the crankshaft has at least three journals, one for a first system comprising the outer pistons and third scotch-yoke, and one for a second system comprising the inner pistons and first and second scotch-yokes, and the effective masses of each of the first and second systems and the throws of their associated crankshaft journal(s) are selected such that the engine is essentially dynamically balanced.

8. An engine according to claim 3, wherein each cylinder has exhaust ports and intake ports formed near its respective ends and fuel injection means communicating with its combustion chamber.

9. An engine according to claim 8, wherein the crankshaft journal(s) associated with the scotch-yoke mechanism(s) for each cylinder are asymmetrically arranged so that the exhaust port or ports of the associated cylinder open before its intake port or ports open and close before its intake port or ports close.

10. An engine according to claim 3, wherein the smaller of the two angles, summing to 360°

, subtended by the scotch-yoke crankshaft journals is about one hundred and fifty-five degrees.

11. An engine according to claim 3, wherein each cylinder comprises a sleeve-valve with one or more exhaust ports at one end and one or more intake ports at the other.

12. An engine according to claim 11, wherein a rigid extension to the end of the sleeve-valve adjacent to the crankshaft contains a hole drivingly coupled to a first eccentric spherical journal on one end of the crankshaft, the extension being split at the hole'"'"'s diameter through a plane normal to the cylinder'"'"'s axis forming a removable cap fastened to the extension in order to enable assembly.

13. An engine according to claim 12, wherein the second cylinder'"'"'s sleeve-valve drivingly couples a second eccentric spherical journal, coaxial with the first, on the other end of the crankshaft, forcing the sleeve-valves to reciprocate in phase but rotate in opposite phase.

14. An engine according to claim 11, wherein the complex motion imparted to the sleeve-valve by its associated crankshaft journal comprises a linear simple harmonic motion component along the cylinder'"'"'s axis and a rotational component about the cylinder'"'"'s axis.

15. An engine according to claim 13, wherein the journals driving the sleeve-valves are positioned to bisect the larger of two angles, subtended by the scotch-yokes'"'"' crankshaft journals.

16. An engine according to claim 11, wherein the mass of both sleeve-valves multiplied by the throw of one of their associated journals substantially equals 2sin(α

/2) multiplied by the mass of a system comprising the outer pistons and third scotch yoke or a system comprising the inner pistons and first and second scotch yokes multiplied by its associated crankshaft journal throw, where α

is 180°

minus the smaller angle subtended by the journals associated with the sleeve-valves.

17. An engine according to claim 16, wherein the smaller angle subtended by the scotch-yoke crankshaft journals is about one hundred and seventy-two degrees (α

=8°

).

18. An engine according to claim 11, wherein both cylinders have their exhaust ports on their inner ends nearest the crankshaft and their intake ports on their outer ends furthest from the crankshaft.

19. An engine according to claim 11, wherein both cylinders have their exhaust ports on their outer ends furthest from the crankshaft and their intake ports on their inner ends nearest to the crankshaft.

20. An engine according to claim 3, wherein axes of the cylinders are parallel but are offset in opposing directions from the axis of the crankshaft.

21. An engine according to claim 3, wherein means are included for applying pressurised air to the intake ports of each cylinder.

22. An engine according to claim 21, wherein two superchargers are included, each being coupled to the exhaust ports of an associated cylinder to receive blowdown gases therefrom and to the intake ports of that associated cylinder to apply pressurised air thereto.

23. An engine according to claim 3, wherein fuel injection means are provided for each cylinder, remote from the crankshaft, reciprocatably received within a tubular member attaching the outer piston to its associated scotch-yoke where multiple radial high pressure fuel jets are released during the injection phase around the time when the inner and outer pistons of the associated cylinder are at their position of closest approach, these jets accessing the associated combustion chamber via small radial holes made through the tubular member which register and envelop the jets during the injection period.

24. An engine according to claim 23, wherein compression of the fuel air mixture in the cylinder causes ignition of the fuel air mixture.

28. An engine according to claim 23, wherein the geometrical configurations and masses of the sleeve-valves are selected so as to counteract the dynamic imbalance caused by the asymmetric motions of the pistons.

25. A two-stroke internal combustion engine comprising:

two opposed cylinders, each cylinder housing two opposed pistons and having one or more inlet ports and one or more outlet ports; and

a crankshaft for driving the pistons, wherein each cylinder comprises a sleeve-valve drivable by the crankshaft to control the opening and closing of the inlet and exhaust port or ports.

27. An engine according to claim 25, wherein the crankshaft has asymmetrically arranged journals for driving the sleeve-valves of the cylinders.

26. A two-stroke internal combustion engine comprising:

two opposed cylinders, each cylinder housing two opposed pistons and having one or more inlet ports and one or more outlet ports; and

a crankshaft having asymmetrically arranged journals for driving the journals from the pistons, wherein each cylinder comprises a sleeve-valve drivable by the crankshaft to control the opening and closing of the inlet and exhaust port or ports.

29. A two-stroke internal combustion engine comprising:

a crankshaft; and

two opposed cylinders having their inner ends nearest to the crankshaft, each cylinder having inner and outer pistons disposed therein and forming a combustion chamber therebetween,

wherein each outer piston is drivingly coupled to the crankshaft by a respective tubular member extending generally axially through the combustion chamber, and wherein fuel injection means housed within the tubular members are arranged to inject fuel radially outwardly into the combustion chamber.

30. A two-stroke internal combustion engine, including:

a crankshaft having a plurality of journals;

two opposed cylinders having their inner ends adjacent to the crankshaft, each cylinder having inner and outer pistons disposed therein and forming a combustion chamber therebetween;

first and second scotch-yoke mechanisms, rigidly attached to the inner pistons, which, acting in unison, drivingly couple the inner pistons to their corresponding journals on the crankshaft; and

a third scotch-yoke mechanism, rigidly attached to the outer pistons, which drivingly couples the outer pistons to their corresponding journal on the crankshaft.