Abstract: A cylinder head for a piston refrigeration compressor that includes at least a first part defining a cooling-gas suction chamber and at least a second part defining a cooling-gas discharge chamber, the first and second parts being distinct from each other, and the suction and discharge chambers each being intended to be brought into communication with a compression chamber provided in the compressor. The cylinder head includes thermal insulation means provided between the first and second parts, the thermal insulation means including an insulation chamber defined by the first and second parts.

Abstract: The invention concerns an element comprising an annular body (9) provided with two series of pins (10, 12) projecting from at least one side of the body (9), the pins (10) of a first series being engaged in grooves (7) of the fixed volute (3) and the pins (12) of a second series being engaged in grooves (8) of the mobile volute (4), to provide an orbital movement of the mobile volute (4) relative to the fixed volute (3), the contact surfaces of the pins (10, 12) of a common series with the walls of the grooves of the corresponding volute being parallel and the contact surfaces of the pins (10, 12) belonging to two series of pins being perpendicular. The annular body (9) is made of a first metal with a specific density and the pins are made of a second metal having a lower density than that of the first metal.

Abstract: Compressor has a fixed scroll and a scroll movable in an orbit relative to the fixed scroll. The fixed and movable scrolls are equipped with a spiral wrap that engage each other and delimit variable-volume compression chambers. The spiral wrap of the movable scroll has a stepped portion extending over at least a portion of its length. At least one of the scrolls defines a passage for communication, during orbital movement of the movable scroll, between two compression chambers, with the ends of the passage terminating respectively on either side of the outer and inner walls of the spiral wrap of the scroll with the passage or inside the outer and inner walls of the spiral wrap of the scroll with the passage. The passage has a check valve for allowing fluid to flow only from the outer wall of the spiral wrap of the scroll with the passage to the inner wall.

Abstract: The invention concerns an element comprising an annular body (9) provided with two series of pins (10, 12) projecting from at least one side of the body (9), the pins (10) of a first series being engaged in grooves (7) of the fixed volute (3) and the pins (12) of a second series being engaged in grooves (8) of the mobile volute (4), to provide an orbital movement of the mobile volute (4) relative to the fixed volute (3), the contact surfaces of the pins (10, 12) of a common series with the walls of the grooves of the corresponding volute being parallel and the contact surfaces of the pins (10, 12) belonging to two series of pins being perpendicular. The annular body (9) is made of a first metal with a specific density and the pins are made of a second metal having a lower density than that of the first metal.