Radial piston engine

A radial piston engine comprising:

• a housing;
• an annular cam disk (3) fixedly mounted in said housing;
• a cylinder block (100) rotatably mounted about an axis with respect to said cam disk (3);
• a plurality of bores (110) extending in said cylinder block radially with respect to said rotational axis;
• a plurality of pistons (120) respectively reciprocally mounted within said bores (110), each piston bore (110) in the cylinder block (100) comprising a recess (113) in the base of the bore, the recess (113) starting from a cylindrical bore wall (112) and extending initially outwardly with respect to a vertical line, under an angle of about 30.degree., and thereupon merges along the arc of a circle with the bottom (116) of the bore;
• cylindrical rollers (14) for supporting said pistons (120) on said cam disk (3), said rollers having two oppositely located end surfaces and axes which extend parallel to the rotational axis of said cylinder block, and
• first recesses machined (108,109) in said cylinder block, in the absence of forming circumferential grooves, in the area of movement of said rollers so as to define a generally rectangular bore adapted to receive roller sections at both end surfaces of the rollers,
• guide surfaces (103,104) for each roller oppositely and laterally arranged in said cylinder block for guiding said roller end surfaces, wherein
• the radially extending depth of the guide surfaces (103,104) ends above the piston ring (123) when the piston (120) has reached its upper dead center.

A method of manufacturing piston and roller receiving chambers in a cylinder block of a radial piston engine, comprising a housing, an annular cam disk (3) fixedly mounted in said housing, a cylinder block (100) rotatably mounted about an axis with respect to said cam disk (3), a plurality of bores (110) extending in said cylinder block radially with respect to said rotational axis, a plurality of pistons (120) respectively reciprocally mounted within said bores (110), cylindrical rollers (14) for supporting said pistons (120) on said cam disk (3), said rollers having two oppositely located end surfaces and axes which extend parallel to the rotational axis of said cylinder block, first recesses (108,109) machined in said cylinder block in the absence of forming circumferential grooves, in the area of movement of said rollers so as to define a generally rectangular bore adapted to receive roller sections at both end surfaces of the rollers, guide surfaces (103,104) for each roller oppositely and laterally arranged in said cylinder block for guiding said roller end surfaces, wherein the radially extending depth of the guide surfaces (103,104) ends above the piston ring (123) when the piston (120) has reached its upper dead center and, characterized in that initially the piston bore (110) is formed in the cylinder block, and that thereupon for the two roller end faces for each piston bore lateral guide surfaces are formed up to a depth which ends above a piston ring of the piston when the piston is in the upper dead point center.