A multi-piece oil scraper piston ring includes a slotted spring element and at least one lamella element which is operatively connected to the slotted spring element and provided with a joint, the spring element being designed as a meander spring that axially receives and radially supports the lamella element, the two end regions of the meander spring being provided with legs that extend approximately parallel to one another and the axial length of which is designed such that the legs at least partially engage in the joint of the lamella element.

The piston ring unit includes a plurality of piston rings and an inner contact ring. A plurality of piston rings are disposed adjacent to each other in an axial direction of the piston such that joints of plurality of the piston rings do not overlap with each other in the axial direction. An inner contact ring is interposed between an outer circumferential surface of the piston and an inner circumferential surface of the piston ring in a state where the inner contact ring extends over all of the plurality of piston rings in the axial direction, and is disposed such that an opening of the inner contact ring does not overlap with the joint of the at least one piston ring as viewed in a radial direction of the piston.

A piston ring set of a cryogenic pump includes a first piston ring and a second piston ring which are dissimilarly shaped and cooperatively shaped to form a hollow cylindrical shape when in abutment to one another. The first piston ring is C-shaped and defines a middle portion disposed between a first end portion and a second end portion. A piston ring gap is disposed between a first distal end of the first end portion and a second distal end of the second end portion. When the first piston ring is in abutment with the second piston ring forming the hollow cylindrical shape, the second piston ring does not extend along the middle portion of the first piston ring while the second piston ring does extend along the first end portion and second end portion of the first piston ring.

A joining support jig includes: a cylinder support for supporting a cylinder; an annular body support for supporting an annular body; and a plurality of movable members that can approach or separate from the cylinder. Each of the plurality of movable members extends from the cylinder side to the annular body side and across an abutment surface between the cylinder and the annular body in the thickness direction of the movable member. Further, the movable members are each formed with a gas supply groove that is depressed in the direction away from the cylinder and has an opening opposing the abutment surface.

A joining support jig includes: a cylinder support for supporting a cylinder; an annular body support for supporting an annular body; and a plurality of movable members that can approach or separate from the cylinder. Each of the plurality of movable members extends from the cylinder side to the annular body side and across an abutment surface between the cylinder and the annular body in the thickness direction of the movable member. Further, the movable members are each formed with a gas supply groove that is depressed in the direction away from the cylinder and has an opening opposing the abutment surface.

A piston ring set of a cryogenic pump includes a first piston ring and a second piston ring which are dissimilarly shaped and cooperatively shaped to form a hollow cylindrical shape when in abutment to one another. The first piston ring is C-shaped and defines a middle portion disposed between a first end portion and a second end portion. A piston ring gap is disposed between a first distal end of the first end portion and a second distal end of the second end portion. When the first piston ring is in abutment with the second piston ring forming the hollow cylindrical shape, the second piston ring does not extend along the middle portion of the first piston ring while the second piston ring does extend along the first end portion and second end portion of the first piston ring.

A piston seal assembly is disclosed comprising a seal and a seal energizer which supports the seal. The piston seal assembly comprises one component that is designed to position the seal energizer in a fixed axial position within the piston groove. In one embodiment, the seal energizer has the shape of a split ring with at least one of its lateral surfaces shaped to position the energizer in a fixed position within a piston groove. In other embodiments the piston seal assembly comprises a spacer that is positioned next to the seal energizer within the piston groove and is designed to position the seal energizer in a fixed axial position. The piston seal assembly can comprise a seal that has a portion which protrudes between the seal energizer and the piston groove wall such that it positions the seal energizer in a fixed axial position within the piston groove.

A multi-piece oil scraper piston ring includes a slotted spring element and at least one lamella element which is operatively connected to the slotted spring element and provided with a joint, the spring element being designed as a meander spring that axially receives and radially supports the lamella element, the two end regions of the meander spring being provided with legs that extend approximately parallel to one another and the axial length of which is designed such that the legs at least partially engage in the joint of the lamella element.

A piston seal assembly is disclosed comprising a seal and a seal energizer which supports the seal. The piston seal assembly comprises one component that is designed to position the seal energizer in a fixed axial position within the piston groove. In one embodiment, the seal energizer has the shape of a split ring with at least one of its lateral surfaces shaped to position the energizer in a fixed position within a piston groove. In other embodiments the piston seal assembly comprises a spacer that is positioned next to the seal energizer within the piston groove and is designed to position the seal energizer in a fixed axial position. The piston seal assembly can comprise a seal that has a portion which protrudes between the seal energizer and the piston groove wall such that it positions the seal energizer in a fixed axial position within the piston groove.

A sealing ring assembly that includes a plurality of segments that forms a seal against a bore of a cylinder. Each pair of adjacent ring segments of the plurality of ring segments are coupled by a respective flexure therebetween. Each respective flexure causes a radially outward force to cause a respective radially outward surface of respective pairs of the adjacent ring segments to seal against a bore of a cylinder and a tangential force to be applied to the sealing ring assembly.