Opposed piston engine and elements thereof

1. An opposed piston engine comprising:

an engine housing;

at least one cylinder housing coupled to the engine housing; and

a first cylinder supported by the at least one cylinder housing, the first cylinder having a first end and a second end opposite the first end, and a central portion located substantially in a center between the first and second cylinder ends, wherein each of the first and second cylinder ends is directly supported by and physically contacts the engine housing, wherein the engine housing has a first portion and a second portion extending from the first portion in a direction perpendicular to a longitudinal axis of the cylinder and the second portion directly supports and physically contacts the first end of the cylinder, and wherein said at least one cylinder housing is formed continuously about the complete circumference of the at least one cylinder and is formed to mount valve assemblies within said at least one cylinder housing.

2. The engine of claim 1 , wherein the engine housing has a third portion extending from the first portion in a direction perpendicular to a longitudinal axis of the cylinder and the third portion directly supports and physically contacts the second end of the cylinder.

3. The engine of claim 1 further comprising a second cylinder having a third end and a fourth end, wherein the second portion extends from a first side of the first portion and further comprising a fourth portion extending from a second side of the first portion opposite the first side, wherein the second portion directly supports the first end of the first cylinder, and the fourth portion directly supports the third end of the second cylinder.

4. The engine of claim 1 wherein the housing second portion has a pair of opposed openings, each opening being structured to enable associated portions of a crankshaft to extend from the first portion and through the second portion.

5. The engine of claim 1 wherein the engine housing has a third portion extending from the first portion and spaced apart from the second portion, and wherein the cylinder first end is supported by the housing second portion and the cylinder second end is supported by the housing third portion.

6. The engine of claim 5 wherein the engine housing second portion is structured to provide a mounting structure for a portion of an associated first crankshaft operatively coupled to a first piston positioned in the cylinder, and wherein the engine housing third portion is structured to provide a mounting structure for a portion of an associated second crankshaft operatively coupled to a second piston positioned in the cylinder,

wherein the third portion directly supports and physically contacts the second end of the first cylinder.

7. The engine of claim 5 wherein the cylinder is supported by the engine housing such that the cylinder is spaced apart from the housing first portion.

8. A cylinder structure for an opposed piston engine comprising a first end and a second end, the cylinder structure further comprising:

an inner cylinder portion having a length and a longitudinal central axis and a plurality of grooves formed along an exterior surface thereof; and

an outer cylinder portion structured to receive the inner cylinder portion therein and to abut the exterior surface of the inner cylinder portion so as to form an associated plurality of coolant passages along the grooves,

wherein said plurality of grooves extend from about the first end to about the second end, for substantially all of the length of the cylinder.

9. The cylinder structure of claim 8 wherein the grooves of the plurality of grooves extend along the inner cylinder portion parallel to a longitudinal central axis of the cylinder.

10. The cylinder structure of claim 8 wherein the grooves of the plurality of grooves are interconnected so as to permit a coolant to flow between adjacent grooves of the plurality of grooves.