The present disclosure is a combination of a cylinder and a piston ring, the combination including a cylinder of an internal combustion engine and a piston ring sliding on an inner peripheral surface of the cylinder. The piston ring has an outer peripheral surface sliding on the inner peripheral surface of the cylinder, and the outer peripheral surface is formed of a substantially hydrogen-free amorphous carbon coating. The Vickers hardness Hd of the amorphous carbon coating and the Vickers hardness Hb of the inner peripheral surface of the cylinder satisfy Hd+Hb≤2500 HV. The ratio ID/IG of the peak intensity of the D band to the peak intensity of the G band in a Raman spectrum obtained by measuring the amorphous carbon coating by Raman spectroscopy is 0.60 or more and 1.33 or less.

The present disclosure is a combination of a cylinder and a piston ring, the combination including a cylinder of an internal combustion engine and a piston ring sliding on an inner peripheral surface of the cylinder. The piston ring has an outer peripheral surface sliding on the inner peripheral surface of the cylinder, and the outer peripheral surface is formed of a substantially hydrogen-free amorphous carbon coating. The Vickers hardness Hd of the amorphous carbon coating and the Vickers hardness Hb of the inner peripheral surface of the cylinder satisfy Hd+Hb≤2500 HV. The ratio ID/IG of the peak intensity of the D band to the peak intensity of the G band in a Raman spectrum obtained by measuring the amorphous carbon coating by Raman spectroscopy is 0.60 or more and 1.33 or less.

A sealing ring includes a first sealing element having a first mating surface and a second sealing element having a second mating surface. A high-pressure boundary extends across at least a portion of the first sealing element and across at least a portion of the second sealing element, and a low-pressure boundary extends across at least a portion of the first sealing element and across at least a portion of the second sealing element. The first mating surface, the second mating surface, or both, includes a recess open to the low-pressure boundary and not open to the high-pressure boundary. The recess may include a groove, for example. The first mating surface is sealed against the second mating surface by a first force acting on the first sealing element and a second force acting on the second sealing element. These forces act to pressure-lock the assembly.

A sealing ring includes a first sealing element having a first mating surface and a second sealing element having a second mating surface. A high-pressure boundary extends across at least a portion of the first sealing element and across at least a portion of the second sealing element, and a low-pressure boundary extends across at least a portion of the first sealing element and across at least a portion of the second sealing element. The first mating surface, the second mating surface, or both, includes a recess open to the low-pressure boundary and not open to the high-pressure boundary. The recess may include a groove, for example. The first mating surface is sealed against the second mating surface by a first force acting on the first sealing element and a second force acting on the second sealing element. These forces act to pressure-lock the assembly.

A piston ring configured to be disposed in a floating piston for use in a vessel of a thermal energy storage system to separate a hot working fluid from a cold working fluid, wherein the piston ring comprises of a plurality of arc segments, each arc segment interconnected by a joint.

An internal combustion engine includes an engine block, a piston, a cylinder head, and a valve train. The engine block includes a cylinder block including a cylinder bore and a crankcase defining a crankcase chamber with a crankshaft positioned within the crankcase chamber. The piston is coupled to the crankshaft and configured to reciprocate within the cylinder bore. The cylinder head is coupled to the cylinder block. The valve train includes a camshaft, a first and second pushrod, a first and second rocker arm, an exhaust valve housed, and an intake valve. The first rocker arm, the second rocker arm, the exhaust valve, and the intake valve each include at least a layer of a low friction material. The first and second pushrod each pass through a pushrod seal to prevent fluid from reaching the rocker chamber to fluidly isolate the rocker chamber from the crankcase chamber.

An internal combustion engine includes an engine block, a piston, a cylinder head, and a valve train. The engine block includes a cylinder block including a cylinder bore and a crankcase defining a crankcase chamber with a crankshaft positioned within the crankcase chamber. The piston is coupled to the crankshaft and configured to reciprocate within the cylinder bore. The cylinder head is coupled to the cylinder block. The valve train includes a camshaft, a first and second pushrod, a first and second rocker arm, an exhaust valve housed, and an intake valve. The first rocker arm, the second rocker arm, the exhaust valve, and the intake valve each include at least a layer of a low friction material. The first and second pushrod each pass through a pushrod seal to prevent fluid from reaching the rocker chamber to fluidly isolate the rocker chamber from the crankcase chamber.

A piston assembly is provided for a human-powered vehicle. The piston assembly includes a main body, a primary seal and a secondary seal. The main body is configured to be movable from a rest position to an actuated position along an actuation direction in a cylinder bore. The primary seal includes a primary seal body arranged on the main body, the primary seal body being made of the first seal material. The secondary seal includes a secondary seal body arranged on the main body at upstream of the primary seal with respect to the actuation direction. The secondary seal body is made of a second seal material that is more elastic than the first seal material.

A wear ring for guidance of two machine components are arranged movably relative to one another along/around a movement axis, which is formed in one piece from a plastic or a reinforced plastic material and which is slit such that it has two free ends. The wear ring has a cross-sectional width W, which at least sectionally, increases in a radial direction towards the rear side of the wear ring. The wear ring has one or more recesses formed on its front side and/or on its the rear side for increasing its deformability and thus facilitate mounting thereof in a mounting groove of a machine element. Furthermore, a wear ring arrangement with a wear ring can be clipped into a mounting groove of one of the machine components of the wear ring arrangement.

A wear ring for guidance of two machine components are arranged movably relative to one another along/around a movement axis, which is formed in one piece from a plastic or a reinforced plastic material and which is slit such that it has two free ends. The wear ring has a cross-sectional width W, which at least sectionally, increases in a radial direction towards the rear side of the wear ring. The wear ring has one or more recesses formed on its front side and/or on its the rear side for increasing its deformability and thus facilitate mounting thereof in a mounting groove of a machine element. Furthermore, a wear ring arrangement with a wear ring can be clipped into a mounting groove of one of the machine components of the wear ring arrangement.