Abstract: To provide refrigeration below 200 K, a Brayton cycle engine contains a light reciprocating piston. The refrigerator includes a compressor, a gas-balanced reciprocating engine having a cold rotary valve, a counterflow heat exchanger, a gas storage volume with valves that can adjust system pressures, a variable speed engine and a control system that controls gas pressure, engine speed, and the speed of the piston. The engine is connected to a load such as a cryopanel, for pumping water vapor, through insulated transfer lines.

Abstract: The invention relates to a piston (1), comprising a ring carrier (2) and a glass piston (3) for observing processes in a combustion chamber (B) of an internal combustion engine, wherein the glass piston (3) is placed upon the ring carrier (2) and is securely connected thereto in the region of an inner casing surface (8) of the ring carrier (2). In order to avoid overly high heat strain in the glass piston (3), the glass piston (3) is connected to the ring carrier (2) via at least one form-fit connection (20), and preferably via a force-fit connection (30).

Abstract: A sleeve for a pneumatic nailer is provided that includes a cylindrical tubular body made of plastic and having a lower edge; and a metal reinforcing ring is integrally secured to the lower edge.

Abstract: A single-piece piston body for an internal combustion engine includes a crown portion having a circumferential ring belt including an oil ring groove configured to accommodate an oil control ring and a skirt portion having a first skirt wall disposed on the major thrust side and a second skirt wall disposed on the minor thrust side of the piston, and two box walls that connect the skirt walls and which are set back with respect to the ring belt. A first plurality and a second plurality of axial drain passages extend from the oil ring groove to the bottom of the crown portion, the first and second pluralities of axial drain passages being substantially centered at opposite box sides of the piston and each plurality of axial drain passages spanning an arcuate portion of about 45-75 degrees.

Abstract: A piston assembly including a piston body having a crown and a skirt, the skirt including at least a major thrust face and a minor thrust face, wherein the piston body defines a bore between the major thrust face and the minor thrust face, and a wear coating applied to the major thrust face and the minor thrust face, the wear coating having a cured thickness of at least about 30 microns.

Abstract: A durable piston is applied in a cylinder of an engine to output internal exploding power and has a piston head and a durable ring unit. The piston head is mounted in the cylinder of the engine, is driven for outputting kinetic energy and has a ring unit mount. The durable ring unit is mounted around the ring unit mount and has a distal ring and a proximal ring. The rings are mounted around the ring unit mount. An inner edge of the distal ring and the proximal ring are separated from the piston head of the piston so forming a first airway and a second airway. When the engine operates, high-pressure air fills the airways and presses the rings against the cylinder. Consequently, the airways maintain contact between the durable ring unit and the cylinder tight to prevent air leakage.

Abstract: A piston 1 contains multiple ring grooves 2, 3 on the outer circumference of the piston 1, and piston rings 4, 10 are mounted in the ring grooves 2, 3. The piston 1 contains oil path grooves 7, 9 extending respectively to the outer circumference of the piston 1 on the upper and lower surfaces of the lowermost ring groove 2, and an oil path groove 12 extending to the outer circumference of the piston 1 on the lower surface of the ring groove 3 just above the lowermost ring groove 2. The weight of the lowermost piston ring 4 is equal to or smaller than the weight of the piston ring 10 just above the lowermost piston ring 4; and expanders 5, 11 are installed on the rear side of the piston rings 4, 10 respectively.

Abstract: A piston assembly including a piston body having a crown and a skirt, the skirt including at least a major thrust face and a minor thrust face, wherein the piston body defines a bore between the major thrust face and the minor thrust face, and a wear coating applied to the major thrust face and the minor thrust face, the wear coating having a cured thickness of at least about 30 microns.

Abstract: The present invention relates to a multi-part piston (10) for an internal combustion engine, having an upper piston part (11) having a piston crown (13), and a lower piston part (12), whereby the lower piston part (12) has pin boss supports (32) and pin bosses (18) connected with them, whereby the upper piston part (11) and the lower piston part (12) each have an inner (21, 25) and an outer (22, 26) support element, which elements delimit an outer circumferential cooling channel (29). According to the invention, it is provided that the inner support elements (21, 25) delimit a cavity (31) that is open toward the pin bosses (18), and that the cavity (31) is provided with a separate cooling oil collector (35) that has at least one cooling oil opening (37, 38).

Abstract: The invention relates to a piston ring whose running surface is provided with a coating containing a plastic material. Said piston ring is characterized in that the coating is composed of at least one polyamide-imide and/or at least one polyether ether ketone with embedded particles which can be embodied as hard material particles, solid lubricant particles, or metallic particles. The invention further relates to a piston/piston ring arrangement comprising at least one inventive piston ring and an agent for coating at least the running surface of the piston ring.

Abstract: An internal combustion engine includes a piston adapted to reciprocate in a cylinder. The piston includes a first portion, a second portion, and a third portion. The first portion of the piston forms a crown surface of the piston, the second portion of the piston forms a piston ring groove of the piston with the piston ring groove arranged and configured to receive a piston ring, and the third portion of the piston forms a crankcase side surface of the piston with the crankcase side surface facing a crankcase of the engine. The second portion of the piston is formed of a material having a higher thermal conductivity than a material forming the first portion of the piston and a material forming a third portion of the piston.

Abstract: A piston device and its manufacturing method are disclosed. The piston device comprises a piston body having at least one annular groove on the side wall of the piston body, and at least one piston ring made of flexible material and mounted in the annular groove. The outer diameter of the piston ring mounted on in the annular groove is larger than the diameter of the piston body, so that the piston ring contacts with the inner wall but the piston body has no contact with the inner wall while the piston device moves reciprocally at the axial direction of the cylinder.

Abstract: A piston is equipped with a skirt that has a sliding surface provided with an oil repellent resin layer. A solid lubricating resin layer and the oil repellent resin layer are exposed on the sliding surface. On the sliding surface, the oil repellent resin layer extends at an incline with respect to the centerline of the sliding surface in a circumferential direction of the piston.

Abstract: The invention relates to a piston ring whose running surface is provided with a coating containing a plastic material. Said piston ring is characterized in that the coating is composed of at least one polyamide-imide and/or at least one polyether ether ketone with embedded particles which can be embodied as hard material particles, solid lubricant particles, or metallic particles. The invention further relates to a piston/piston ring arrangement comprising at least one inventive piston ring and an agent for coating at least the running surface of the piston ring.

Abstract: An internal combustion engine includes a piston adapted to reciprocate in a cylinder. The piston includes a first portion, a second portion, and a third portion. The first portion of the piston forms a crown surface of the piston, the second portion of the piston forms a piston ring groove of the piston with the piston ring groove arranged and configured to receive a piston ring, and the third portion of the piston forms a crankcase side surface of the piston with the crankcase side surface facing a crankcase of the engine. The second portion of the piston is formed of a material having a higher thermal conductivity than a material forming the first portion of the piston and a material forming a third portion of the piston.

Abstract: An oilless reciprocating fluid machine has a piston mounted to a connecting rod by inserting a piston pin in a pin bore of a cylinder. The piston is reciprocally moved up and down in the cylinder with reciprocating of the connecting rod. A reinforcement plate is embedded in the top wall of the piston or attached on the lower surface of the top wall to increase strength of the piston. The reinforcement plate may be formed in various shapes.

Abstract: The invention relates to a molded piston, in particular an injection-molded piston (1) of fiber-reinforced plastic, which is seated slidably in a receiving bore (2) of a housing (4) and is embodied as a cup-shaped body with a piston bottom (6) and a sleevelike piston wall (8) protruding away from the bottom, and the face (10) of the piston bottom (6) pointing away from the piston wall (8)is pressure-loadable, and there is at least one injection point (46) oriented with a molding channel of a molding tool. The invention proposes that the injection point (46) is disposed on the other face (22) of the piston bottom (6), that is, the face pointing away from the pressure-loadable face (10), and the piston bottom (6), because of one or more recesses (48) present in this face (22), has a lesser wall thickness in the region of the injection point (46) than in the regions (52) adjoining it.

Abstract: A method of forming a floating piston includes fabricating a piston cup, wherein the piston cup includes a top, a sidewall void of any seal-gripping irregularities, and an open end, and forming an elastomer seal over the sidewall of the piston cup. A floating piston includes a piston cup having a top, a sidewall extending about the periphery of the top and an open end, wherein the sidewall is void of any seal-gripping irregularities; and an elastomer seal formed about the sidewall of the piston cup.

Abstract: A piston or plunger and a method for making the same A piston or plunger comprises a piston body and a sealing member. The piston body is preferably made from metal by moulding, such as casting or pressure moulding and sintering. The sealing member is made from a thermoplast, such as polytetrafluoroethylene (PTFE). The piston body has an outer or an inner peripheral surface part in which axially extending depressions or grooves are formed during moulding of the piston body. The axially extending grooves may be open at one or at opposite ends. An annular sealing member blank is applied to the peripheral surface part and is deformed and forced into tight engagement with the peripheral surface part and into the grooves or depressions formed therein. The sealing member formed is also exposed to a heat treatment. The piston or plunger having the sealing member applied to an outer peripheral surface part may, for example, be used in shock absorbers.

Abstract: The compressor contains at least one piston (5) guided in a dry-running manner which, together with a cylinder insert (33), bounds a ring gap which is open over the common longitudinal section in each case and permits a leakage flow of the compressed medium. The piston (5) is coupled via a piston rod (42) to a support part (38) which is displaceably guided in the direction of its longitudinal axis (6) and is connected to a drive device. The piston rod (42) cooperates with the piston (5) and the support part (38) via support surfaces (43) which are convex at the end faces and permit relative movements of the support part (38) with respect to the piston (5) which extend transversely to the longitudinal axis (6). Accordingly, a parallel guidance of the piston (5) in the cylinder insert (33) is achieved which is not influenced by oscillations of the driving parts.

Abstract: The present invention aims at reducing the amount of oil consumption in a piston using a piston ring continuously formed of resin without being provided with an abutment. A stepped portion is formed on a third land, which is located below a second ring having a construction wherein an outer ring continuously formed of polyimide without being provided with an abutment is pressed against a cylinder wall by a coil expander via an inner ring continuously formed of PTFE without being provided with an abutment. Oil spill ports are provided so as to allow communication between the stepped portion and an inner wall of the piston.

Abstract: A three-dimensional piston molding is fabricated from a mixture of chopped, carbon tow filaments of variable length, which are prepregged with carbonaceous organic resins and/or pitches and molded by conventional molding processes into a near net shape, to form a carbon-fiber reinforced organic-matrix composite part. Continuous reinforcement in the form of carbon-carbon composite tapes or pieces of fabric can be also laid in the mold before or during the charging of the mold with the chopped-fiber mixture, to enhance the strength in the crown and wrist-pin areas. The molded chopped-fiber reinforced organic-matrix composite parts are then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. These pyrolized parts are then densified by reimpregnation with resins or pitches, which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes.

Abstract: An improved structure for a reciprocating internal combustion engine or compressor piston fabricated from carbon-carbon composite materials is disclosed. An integral ring carbon-carbon composite piston, disclosed herein, reduces the need for piston rings and for small clearances by providing a small, flexible, integral component around the piston that allows for variation in clearance due to manufacturing tolerances, distortion due to pressure and thermal loads, and variation in thermal expansion differences between the piston and the cylinder liner.

Abstract: A piston and ring assembly operative within a cylindrical bore wall to retain fluid to one side. The piston has a side wall for movement along the cylindrical wall and has one or more spaced grooves in the side wall, each groove defining a pair of interior groove surfaces spaced apart a uniform distance; at least one sealing element presenting a pair of opposed surfaces operating between and along the pair of groove surfaces, the sealing element being capable of engaging the cylindrical wall, the spacing between the opposed surfaces of the sealing element and the pair of interior surfaces of the groove being no greater than ten microns; and a solid film lubricant mixture coating the groove surfaces and the opposed surfaces of the sealing element, whereby surface adhesion of the fluid, present in the spacing, inhibiting migration of such fluid through the spacing and flutter of the sealing element, in said spacing, being essentially eliminated.

Abstract: A piston for developing compression within the cylinder of a combustion engine or other type compression generating apparatus; said piston being a two-piece assembly, whereas the topside portion, or traditionally known as the crown, being of relative disc-shape in relation to asymetrics of said piston, is connected to the lower portion, or traditionally known as the skirt, by a distinct fastening means that consist of said crown being concaved from the underside and having multiple vertically positioned ridges that align the inside perimeter of said underside. Said skirt has another set of matching vertically positioned ridges that align the outer perimeter at the top of said skirt, as said top is appropriately sized to match said underside of said crown so that said crown may be press-fitted to said top of said skirt for a rigid and complete piston assembly.

Abstract: A ceramic-metal composite structure which minimizes tensile ceramic loads and accommodates differences in thermal expansion characteristics between a metal member and a ceramic member without reliance on precise feature control for either member. The composite includes a mechanical retainer which allows a loose fitting relationship between the metal and ceramic members. The ceramic member is secured within a receiving bore in the metal member by the retainer in a manner which eliminates the need for precise machining of the ceramic and metal members. The metal member may be configured to accept either an internal or an external mechanical retainer element. The composite ceramic-metal structure of the present invention finds particular utility in forming a durable wear-resistant interface in internal combustion engine actuator or actuating components, such as compression brake master pistons.

Abstract: A piston assembly (10) for use in an engine. The piston assembly (10) includes a piston body (12) with a liner (24) covering the interior surface (22) thereof. The liner (24) imbues added strength and dimensional stability during casting, machining, engine assembly, and in service. At the same time, piston weight for a given volume is reduced without sacrificing strength. The invention also includes a method for manufacturing the piston assembly (10).

Abstract: A piston for an internal combustion engine comprises at least a pair of ribs arranged between an inner surface portion of a skirt and side portions of pin bosses. The ribs are symmetrical with respect to a thrust center line of the piston and have in a longitudinal direction thereof a center line which is positioned to be lower than an axis of a piston pin.

Abstract: This heat-insulating piston has a piston head comprising a piston head base portion consisting of a ceramic material, a heat-insulating member jointed to the piston head base portion and consisting of a whisker fired member of the same ceramic material as that of the piston head base portion, and a laminate jointed to the surface of the heat-insulating member that faces the combustion chamber, as well as to the surface that slides and consisting of the same ceramic material as that of the heat-insulating member. The heat-insulating member is stably jointed to the piston head base portion and laminate by utilizing the same ceramic material for the heat-insulating member, piston head base portion and laminate, whereby the strength of the piston head can be improved. Furthermore, the heat-insulating capability of the piston can be improved, while the thermal capacity of the laminate is made small, whereby the suction efficiency can also be improved.

Abstract: A ceramic-metal composite structure which minimizes tensile ceramic loads and accommodates differences in thermal expansion characteristics between a metal member and a ceramic member without reliance on precise feature control for either member. The composite includes a mechanical retainer which allows a loose fitting relationship between the metal and ceramic members. The ceramic member is secured within a receiving bore in the metal member by the retainer in a manner which eliminates the need for precise machining of the ceramic and metal members. The metal member may be configured to accept either an internal or an external mechanical retainer element. The composite ceramic-metal structure of the present invention finds particular utility in forming a durable wear-resistant interface in internal combustion engine actuator or actuating components, such as compression brake master pistons.

Abstract: A metal of which the body of a piston is formed contains iron as its main component, and the configuration of a silicon nitride member, the high-temperature strength of the silicon nitride material that composes the silicon nitride member, the melting point of the iron-containing metallic material and the inserting conditions satisfy the following formulae (1) and (2) or formulae (3) and (4):k.sub.1 .multidot..DELTA.T.multidot.(1/R.sub.1 -1/R.sub.2)+k.sub.2 .multidot.l.sup.2 .multidot..DELTA.T<0.5 .sigma..sub.c ( 1)T.sub.c =T.sub.m -0.413.multidot.l.multidot..DELTA.T (2)k.sub.1 .multidot.T.sub.m .multidot.(1/R.sub.1 -1/R.sub.2)+k.sub.2 .multidot.l.sup.2 .multidot.T.sub.m <0.5.sigma..sub.c ( 3)T.sub.c =T.sub.m -0.413.multidot.l.multidot.T.sub.m ( 4)The joint between the silicon nitride member and the metallic material need not be subjected to machining. Therefore, the manufacturing process is simple and the cost is low.

Abstract: A piston, e.g. for an internal combustion engine, comprises a crown (16) and a skirt (12). The skirt (12) has an aperture (22) in which an insert (14) of a different material from the remainder of the skirt is secured. The insert (14) may be of plastics material injection moulded into a metal skirt. The insert (14) provides a plurality of pads (34) which extend from a thrust surface of the skirt so that the pads can transmit lateral forces and cause lubricant to be forced over the pads by hydrodynamic action during reciprocation of the piston.

Abstract: A piston of an internal combustion engine, arranged to suppress engine noise and vibration while improving the frictional resistance and seizure resistance of a piston skirt. The piston skirt of the piston is formed at its outer peripheral surface with a pair of depressions. A projection having a spherical surface is formed at the bottom surface of each depression and protrudes radially and outwardly relative to the piston skirt. A heat-resistant pad is loosely fitted in each depression and has a cylindrical inner surface which is in slidable contact with the spherical surface of the projection, so that the pad makes its swinging movement in accordance with the oscillating rotational movement of the piston body around the axis of a piston pin during the reciprocating action of the piston.

Abstract: Disclosed is a piston for an internal combustion engine, which includes a land portion, and a skirt portion including a non-coated portion which is formed in an arbitrary shape on a sliding portion thereof and a coated portion which is formed on a sliding portion thereof other than the sliding portion on which the non-coated portion is formed. When the piston is descending, an oil which has adhered on a cylinder bore is introduced into the non-coated portion and accordingly an oil film is established in the non-coated portion. Since the advantageous effects of the coated portion and the oil film are combined in the piston, the sliding resistance can be reduced remarkably. Hence, the coated portion can be inhibited from wearing out, and its function of the sliding resistance reduction can be maintained for a long period of time. In addition, since the non-coated portion does not work as a sliding surface, there arises a reduced sliding surface area which also results in the reduction of the sliding resistance.

Abstract: A piston comprises a crown (12) and a skirt (20). At least a portion of the skirt (20) is formed of a ceramic material injection moulded directly on to the remainder of the skirt (20) or the crown (12). The ceramic material provides a plurality of pads (24) which projects from a thrust surface of the skirt (20) to transmit lateral forces against a wall of an associated cylinder.

Abstract: The piston comprises a crown (12), and a skirt 30 made of plastics material secured to the crown. The crown (12) is formed integrally with a depending boss (16) arranged to receive a gudgeon pin (18) by which the piston is connected to a connecting rod (24). The skirt (30) encircles the boss (16) and is spaced therefrom.

Abstract: In a piston and connecting rod assembly for internal combustion engines, which assembly comprises a spherical small end portion, which is movably mounted in a recess of the piston head and in a retaining ring and which is connected to the skirt of the piston, the load-carrying capacity of the piston, which consists of a pressure-cast aluminum alloy, is increased in that the piston is reinforced by fibers, and a ring carrier which has open pores and is embedded in the ring-carrying portion and is connected thereto by a metallic bond, and a collar serving as an abutment for the retaining ring is integrally cast with the piston skirt on the inside thereof.

Abstract: The present invention relates to an oilless reciprocating compressor and expansion apparatus each comprising a piston body to which a piston ring made of a self-lubricating material is fitted and a metal cylinder, and in the first invention and the second invention a self-lubricating material can be formed on the piston itself or on the circumferential surface side thereof without influencing adversely the durability of the piston itself by the compression heat at the piston top, and in the third invention a ring groove formed into the shape of the letter C whose ends are spaced a little is provided in the piston circumferential surface at least whose surface side is made of a self-lubricating material, and said ring groove is positioned on the side thrust line orthogonal to the piston pin, so that the compression efficiency is improved.

Abstract: In a light alloy piston for use in diesel engines for an indirect fuel injection, a body of fibrous material is embedded in the cast piston head and is formed with a shallow combustion recess. In order to improve the conduction of heat outside the portion formed with the combustion recess, the body of fibrous material has a larger height on the side that is formed with the combustion recess than in the remaining portion of the piston head.

Abstract: In a heat-insulating piston comprising a ceramic cylindrical member having the lower end surface thereof in contact with the outer peripheral upper end surface of a piston skirt member, a head base member having the peripheral portion thereof in contact with an inner peripheral step portion of the cylindrical member and fixed to the piston skirt member, a heat-insulating member disposed on the head base member and a ceramic thin film member disposed on the heat-insulating member and having the peripheral portion thereof bonded to the cylindrical member, this invention relates to a heat-insulating piston which inserts metallic heat-resistant members between the inner peripheral step portion of the cylindrical member and the peripheral portion of the head base member in order to prevent the occurrence of a gap between the thin film member and the heat-insulating member.

Abstract: An internally-chilled piston for an internal combustion engine is provided. This piston comprises a piston body made of an aluminum alloy and a piston head including a cylindrical member and a ring-shaped member engaging the outer peripheral surface of the cylindrical member by a shrink fit bonding. The cylindrical member constitutes the central portion of the piston head, while the ring-shaped member constitutes the periphery thereof. On the surface of the ring-shaped member which contacts with the melt forming the piston body during casting, an aluminized layer is formed which chemically connects the ring-shaped member and the piston body to increase the mechanical strength of bonding therebetween.

Abstract: Disclosed herein is a method of manufacturing a piston comprising the steps of providing a shell comprising graphite fibers formed to include the general shape of an open-ended cylinder having an outer periphery, and casting metal to form at least a portion of the piston so that the shell is included and at least a portion of the outer periphery of the shell is exposed. Also disclosed herein is a piston comprising a mesh of graphite fibers having a generally cylindrical shape and defining mesh voids, structural material filling at least some of the mesh voids so that an exterior cylindrical surface of the piston is defined to include at least portions of at least some of the fibers.

Abstract: A fiber reinforced wire set along the edge of an open combustion chamber, which is provided in the piston head of a piston, is remelted with the edge of the combustion chamber, and solidified in order to reinforce the edge of the combustion chamber.

Abstract: A piston-ring arrangement for use in an internal combustion engine including a cylinder with a piston axially displaceable within the cylinder and at least one piston ring guided in the cylinder. The cylinder, piston and piston-ring are made of a ceramic material. The piston ring is formed of two circumferentially extending parts and is mounted in a groove in the circumferentially surface of the piston. The groove has a depth greater than the corresponding radial depth of the piston ring so that a spring element can be positioned between the base of the groove and the piston ring for biasing the piston ring radially outwardly. The spring element can be annular member with a corrugated shape or a multi-part ceramic member shaped to provide a biasing action.

Abstract: A piston head has a cavity and a central projection projecting into the cavity. A ceramic insert is cast in a piston body so as to cover a piston head portion defining the cavity except the central projection-and-its adjacent piston head portion. The ceramic insert has an edge defining a hole through which the central projection projects into the ceramic insert. In one form of the embodiment, a clearance is provided between the edge of the ceramic insert and the central projection-and-its adjacent piston head portion.

Abstract: Pistons for internal combustion engines, particularly compression ignition engines. The pistons have insulating crowns and include a crown having a cap thereon, extending over the crown surface area, the crown cap being composed of an iron-based or a nickel-based alloy and having on the underside thereof ribs which are encast into an aluminium alloy which forms the piston body. The crown cap further includes a ceramic insert encapsulated therein. The ceramic insert may also be leached out by chemical means to leave a void in the cap.

Abstract: A method and apparatus for reducing oil consumption and oil deterioration in a reciprocating engine. The engine is provided with ceramic rings and ceramic cylinder linings. Minimal oil lubricant is adsorbed on the surface layer of the rings and liners to form a lubricating boundary-film on the rings and linings. Excess oil lubricant is restricted from entering the piston ring/cylinder lining region to preclude the formation of a hydrodynamic, full film lubricant layer between the rings and linings. Several engine designs are disclosed.

Abstract: A reinforced lightweight metal piston having fibers within the piston crown to reinforce the crown surface to improve the thermal properties and wear resistance of the crown surface. The reinforcing fibers are embedded in the piston metal using a pressure casting process used to manufacture the piston. The fibers are selected from the group of aluminum silicate, alumina, silicon carbide, silicon nitride, boron, boron carbide and graphite. The fibers can be orientated in the preform in several various directions. The wear resistance of the piston crown can be further increased by the addition of a ferrous heat plug. The fiber reinforced portion is located around the heat plug and provides improved physical and mechanical properties of the piston crown to reduce cracking of the crown around the heat plug and loosening of the heat plug due to metal creep.

Abstract: The invention is an improvement in a lightweight carbon-carbon composite piston, the improvement comprehending the use of near-net shape knitted or warp-interlock pre-forms to improve the structural qualitites of the piston. In its preferred embodiment, a one piece, tubular, closed-ended, knitted pre-form (a sock) of carbon fibers (11) embedded within the matrix of the piston structure forms the crown (12), side wall (15), skirt (16) and inner surface (18) of the piston, and wrap-interlock pre-forms strengthen the piston crown and wrist pin bosses.

Abstract: A piston has a piston head made of ceramics, and includes a ceramic piston head having a male rounded thread portion at the outer periphery thereof, a metal piston body having a depression in the top portion for receiving the piston head, and a female rounded thread at the inner periphery of the depression for mating with the male thread portion. A rotation restraint member is provided between the male thread portion and the female thread portion for restraining the piston head from turning with respect to the piston body. The ratio of the height of the thread to the pitch preferably is from 1/4 to 1/2.