Bourke type engine

In an internal combustion engine having at least two cylinders disposed coaxially and oppositely so that the free ends of piston rods extending from pistons reciprocable in said cylinders, may be connected by a yoke in coaxial alignment with each other and with the cylinders, to reciprocate concurrently as a unit, said yoke having means rotatably to engage a rotating crank by which the force developed by reciprocation of the pistons is converted to rotating driving motion, the improvement which comprises:

• a cylindrical recess in the underside of each piston head, said recess being defined in part by a cylindrical wall coaxial with the piston head and extending outwardly therefrom for a predetermined distance, the inside diameter of said cylindrical wall being slightly greater than the outside diameter of the piston rod insertable in said recess, one end of said piston rod being insertable in said recess to abut the piston head, said rod end being diametrically orificed to receive therethrough a wrist pin, and said cylindrical wall being orificed diametrically in register with the orifice in the rod end to permit the wrist pin also to be passed through said cylindrical wall, the orifices in said cylindrical wall being configured slightly elliptically to allow for some lateral play of the wrist pin in the last said orifices when the piston is reciprocated during operation of the engine.

In an internal combustion engine having at least two cylinders disposed coaxially and oppositely so that the free ends of piston rods extending from pistons reciprocable in said cylinders may be connected by a yoke assembly in coaxial alignment with each other and with the cylinders to reciprocate concurrently as a unit in a first direction, said yoke assembly having means rotatably to engage and reciprocate in a second direction perpendicular to said first direction a rotating crank by which the force developed by reciprocation of the pistons is converted to rotating driving motion, the improvement in the yoke assembly which comprises:

• a housing, said housing defining a rectangular passage extending in said second direction, and being disposed equidistant from both pistons, said housing having means in opposite walls to receive and fixedly hold the free end of the piston rod extending from each piston and in said coaxial alignment, said passage being defined at least in part by a pair of opposing races, said races lying in planes parallel to each other and perpendicular to the common cylinder and piston rod axis;
• a block slider reciprocable in and between, and having opposite faces in contact with, said opposing races in said second direction, said block slider being cylindrically orificed transversely of both said first and second directions, to engage rotatably the said crank rotatable about an axis of rotation parallel to the axis of said cylindrical slider orifice;
• each of said races being grooved to reduce the bearing surface contacted by said slider block and to provide oil flow passages in the surfaces of said races.

In an internal combustion engine having at least two cylinders disposed coaxially and oppositely so that the free ends of piston rods extending from pistons reciprocable in said cylinders may be connected by a yoke assembly in coaxial alignment with each other and with the cylinders to reciprocate concurrently as a unit in a first direction, said yoke assembly having means rotatably to engage and reciprocate in a second direction perpendicular to said first direction a rotating crank by which the force developed by reciprocation of the pistons is converted to rotating driving motion, the improvement in the yoke assembly which comprises:

• a housing, said housing defining a rectangular passage extending in said second direction, and being disposed equidistant from both pistons, said housing having means in opposite walls to receive and fixedly hold the free end of the piston rod extending from each piston and in said coaxial alignment, said passage being defined at least in part by a pair of opposing races, said races lying in planes parallel to each other and perpendicular to the common cylinder and piston rod axis;
• a block slider reciprocable in and between, and having opposite faces in contact with, said opposing races in said second direction, said block slider being cylindrically orificed transversely of both said first and second directions, to engage rotatably the said crank rotatable about an axis of rotation parallel to the axis of said cylindrical slider orifice;
• each face of said slider block in contact with one of said races being grooved to reduce the actual surface thereof in contact with said one of said races and to provide oil flow passages between said bearing surface and said races during reciprocation of said slider block in said passage.