Abstract: Exemplary embodiments are disclosed that include multi-voltage contactors, controls, and related methods.

Abstract: A piston arrangement for a clean combustion engine, such as a hydrogen engine. The piston arrangement comprises a piston configured for reciprocal movement inside a cylinder having a cylinder wall, the piston having a piston head configured to face a first compartment with pressurized gas, a sealing arrangement comprising at least one sealing ring configured to be arranged to seal the piston to the cylinder wall and separating the first compartment from a second compartment, and a water channel extending from an interior of the piston to the sealing ring to provide water for lubricating the sealing ring. The piston head comprises a pumping element configured to be arranged to pressurize the water in the water channel by pressurised gas in the first compartment.

Abstract: A hydraulic rod in reciprocating movement within a barrel of a hydraulic cylinder along a longitudinal direction of the barrel, and a method of manufacturing thereof, a surface finish of the rod comprising valleys, wherein the rod further comprises microporosities on its surface, the microporosities having a depth at least equal to a depth of the valleys.

Abstract: Provided are, among other things, pistons and piston noses. One representative embodiment involves a brake piston that includes a piston body and a top surface, in which the top surface is wider than the piston body and has a small portion that is slightly raised, relative to the rest of the top surface, so that when in use only the small raised portion makes contact with a backing plate of a brake pad.

Abstract: An internal-combustion engine has a crankcase, with at least one cylinder for accommodating a piston, the inner face of which cylinder is provided with a coating forming a running surface for the piston. The coating has a plurality of pores and the average size of the pores and/or the pore surface proportion varies over the length of the cylinder.

Abstract: A spring brake chamber includes a first case, a second case, and a coupling case. The first case includes an open end, a closed end, and an open end portion. The open end portion of the first case includes a tapered outer positioning portion having a diameter that increases toward the open end. The coupling case couples the first case and the second case. The coupling case includes an open end closer to the first case and an open end portion. The open end portion of the coupling case includes a tapered inner positioning portion having a diameter that decreases toward the open end. The first case is positioned relative to the coupling case by attaching the outer positioning portion to an outer side of the inner positioning portion.

Abstract: A piston having a piston crown with a combustion chamber, and a circumferential ring belt extending from the piston crown and having a plurality of ring grooves separated by piston lands. At least one of the piston lands, ring grooves or top surface of the crown is provided with a coating comprising hexagonal boron nitride. The coating can be made solely of hexagonal boron nitride, or can additionally include a resin. The coating can be a single layer coating or a multiple layer coating.

Abstract: The Oil Jet for Increased Efficiency system makes use of internally developed, and stored, oil pressure to direct additional force to assist moving parts in an internal combustion engine, rotating device of any nature, and/or any power producing mechanism, to assist in overcoming frictional, compression, drag, and other resistive forces within said mechanism in order to increase efficiency. Applications include, but are not limited to, timed application of said oil jet to assist in compression and exhaust strokes. Stead-state and/or timed application to rotating parts, including flywheel, alternator, transmission parts and other rotating parts to provide continuous additional force to assist in overcoming mechanical, frictional and other losses within the system.

Abstract: The invention relates to a piston (10, 110) for an internal combustion engine. Said piston comprises a piston head (11), a piston skirt (12) and a peripheral recess (24) between the piston head (11) and the piston skirt (12), an annular peripheral cooling channel (17), which is open towards the bottom and which is closed by a closing element (18), being provided in the piston head (11), and the piston skirt (12) having fillets (21) which are connected to the bottom of the piston skirt (11) and interconnected via bearing surfaces (23, 123). According to the invention, at least one projection (26, 126) is formed in the region of a free end face (25, 125) of the bearing surfaces (23, 123) and extends radially into a region of the cooling channel (17), said projection matching an opening (19) in the closing element (18) of the cooling channel (17).

Abstract: A lubricating configuration in a two-stroke cycle, opposed-piston engine for a piston wristpin minimizes losses in oil pressure at the wristpin as the piston approaches bottom center and reduces the required oil supply pressure to the engine. The wristpin is constructed to absorb and store oil pressure energy when oil pressure at the wristpin is high, and to release that stored energy to pressurize the oil at the wristpin when connecting rod oil pressure is low.

Abstract: A linear motion device includes a housing which extends in a longitudinal direction, and in which a rotor movable in the longitudinal direction is accommodated, the housing including a lubricant supply device, via which the rotor may be supplied with lubricant. The lubricant supply device includes a plunger mounted on the housing and movable transversely to the longitudinal direction, and a spring via which the plunger may be pushed against the rotor, to establish a lubricant supply connection to the rotor via the plunger.

Abstract: A piston (20) includes a piston skirt (30) extending along a longitudinal axis (L) and having a pair of convex outer surfaces (42) facing opposite one another. Each of the outer surfaces (42) include an oil reservoir (44) above the pin bore axis (P) and an oil recess (46) below the pin bore axis (P) and spaced from the oil reservoir (44) by an intervening oil spreading area (48). The oil reservoir (44) and oil recess (46) each include a bottom (50) extending over an area of the outer surface (42) and surrounded by ramped side walls (52). The oil recess (46) and oil reservoir (44) include radiused corners (54) at a transition between the outer surface (42) and at the bottoms (50), so that the oil reservoir (44), oil recess (46), and outer surface (42) are free of sharp edges.

Abstract: The invention relates to an eccentric pump including a frame, a pump shaft which can be driven using a driving device and is mounted to be rotatable about a main axis that is stationary relative to the frame, an eccentric sleeve which is mounted in an axially movable manner on a pump shaft section, an anti-rotation element which is effective between the pump shaft section and the eccentric sleeve), several pump elements which are stationary relative to the frame and are provided with displacement elements that can be moved in a radial direction relative to the main axis, act upon a fluid contained in swept volumes of the pump elements, and are moved against a fluid pressure by an external surface of the eccentric sleeve, and at least one spring element which acts upon the eccentric sleeve in an axial direction.

Abstract: Methods and apparatus are provided for lubricating a piston-to-shoe interface in a hydraulic motor or pump. Piston assemblies are installed in a housing that are each adapted to receive a reciprocating drive force and are each configured, in response thereto, to cyclically move between an intake direction and a discharge direction. Each piston assembly includes a piston and a piston shoe, and the piston, the piston shoe, or both have a plurality of pockets formed in a surface that defines a piston-to-shoe interface. When the pistons cyclically move, liquid is supplied to each piston-to-shoe interface to form a hydrostatic bearing at each piston-to-shoe interface. A portion of the liquid that is supplied to each piston-to-shoe interface is selectively supplied to and from one or more of the plurality of pockets.

Abstract: An opposed piston engine includes at least one cylinder with a bore surface and longitudinally-spaced exhaust and intake ports that open through the sidewall of the cylinder. A pair of opposed pistons is disposed in the cylinder for sliding movement along the bore surface. An oil-retaining surface texture pattern in an interface between the pistons and the bore surface extends in a longitudinal direction of the cylinder, aligned with bridges of at least one port. The surface texture pattern includes a plurality of separate recesses on an outside surface of a skirt of each piston. Alternatively, or in addition, the surface texture pattern includes a plurality of separate recesses extending in a longitudinal direction of the cylinder, aligned with bridges of at least one port.

Abstract: A reciprocating compressor comprises: a cylinder having an oil pocket on an inner circumferential surface of a piston insertion hole for inserting a piston with a predetermined width and depth; and a piston having a bearing portion protruding so as to slidably contact an inner circumferential surface of the piston insertion hole, and inserted into the piston insertion hole of the cylinder, wherein the bearing portion is formed to have a length shorter than that of the oil pocket of the cylinder. Accordingly, a frictional loss between the cylinder and the piston is reduced.

Abstract: In a hydraulic rotary machine having rotational shaft provided within a casing a rotational shaft, a cylinder block rotationally interlocked with the rotational shaft and formed with a plural number of cylinder bores, and pistons slidably received in the cylinder bores and adapted to slide back and forth within the cylinder bores while the rotational shaft and the cylinder block are put in rotation in synchronism with each other, a multitude of minute pits are formed at least either on sliding surfaces on the side of the cylinder bores, each one of the minute pits are in an elliptical shape defining a moderately sloped surface in one side and an acutely sloped surface in the other side, and the moderately sloped surfaces of the minute pits are oriented to face a direction in which said pistons are put in sliding movement in said cylinder bores under a greater load than in the other direction.

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 for an internal combustion engine is provided. The piston crown includes an interior surface that defines at least in part a cooling gallery and a cooling gallery surface within the piston. An annular surface may defines at least in part an annular passageway that allows fluid communication between an outer surface of the piston and the cooling gallery. Opposing annular surfaces may be abutted with a predetermined force, thereby limiting fluid flow from the cooling gallery to an outer surface of the piston. Further, an annular surface may extend into the cooling gallery to form a deflector along the cooling gallery surface, thereby limiting fluid flow from the cooling gallery to an outer surface of the piston.

Abstract: The invention relates to a piston of an internal combustion engine comprising an upper part (1) and a lower part (3) that consist of a respective light metal alloy (15) and to an associated method for increasing the thermal load-bearing capacity of a multi-part piston that is subjected to high thermal stress in an internal combustion engine. The piston is provided with at least one insulating element, in particular a gap (7) between the lower part (3) and the upper part (1), at least one piston ring carrier (6), which consists of a different material from that of the upper part (1) and the lower part (3), in particular of steel or grey cast iron, being located next to said gap as a component. A thermal current that is introduced into the piston base (2) is prevented from dissipating via the piston ring carrier (6) by means of the insulating element.

Abstract: A piston 10 for an engine has a number of elongate pockets 21, 22, 23, 24 each of which is arranged at an angle relative to a longitudinal axis HP2 of a contact zone 15 on the thrust and anti-thrust sides of the piston 10. The pockets 21, 22, 23, 24 are arranged in two columns C1, C2 one on each longitudinal side of a central portion 20 of the contact zone 15 to form partial barriers to reduce the loss of oil from the central portion 20 during use of the piston 10. The pockets 21, 22, 23, 24 are oriented differently above and below a transverse axis HP1 of the contact zone 15 so as to reduce the loss of oil irrespective of the direction of motion of the piston 10.

Abstract: A piston for an internal combustion engine, the engine having a connecting rod coupled to a wristpin, the wristpin being connected to the piston for pivotal movement about an axis, the piston comprising: a top portion and a generally cylindrically-shaped wall portion extending from the top portion, the top and wall portions defining a skirt cavity, the top portion having thereon a downwardly extending projection with a downwardly facing bearing surface for the wristpin, the bearing surface extending in the direction of the axis and defining a portion of a cylinder centered on the axis, and the projection having opposite sides facing the skirt cavity; at least one lubricant passage extending through the projection from one of the opposite sides and over the bearing surface to the other of the opposite sides; and a lubricant opening communicating between the lubricant passage and the bearing surface to supply lubricant to the bearing surface and to the wristpin.

Abstract: A plunger is inserted into a slide hole of a cylinder body provided between a pressurizing chamber and a drive cam, so as to reciprocate within the slide hole. The drive cam and a coil spring move the plunger toward the drive cam so that fuel is sucked into the pressurizing chamber, and also move the plunger toward the pressurizing chamber so that the fuel in the pressurizing chamber is pressurized. A clearance between the plunger and a wall of the slide hole forms a flow passage of the fuel discharged from the pressurizing chamber. In the high-pressure fuel pump constructed as above, a fluid reservoir is provided in the flow passage. The capacity of the fluid reservoir increases as the plunger moves toward the drive cam, and decreases as the plunger moves toward the pressurizing chamber.

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: A driving mechanism for a powered hammer having a motor and a tool holder includes a ram mounted for reciprocation in a guide tube section. The ram has a radially outwardly projecting sealing portion and an outer circumferential surface that defines a helically shaped vent channel running from a front end portion of the circumferential surface to a rear end portion of the circumferential surface and being interrupted by the sealing portion. A piston is driven in reciprocating motion of the motor such that an air cushion is generated in a space between the ram and the piston to cause an impact on the tool bit by movement of the ram towards the tool bit. The space between the ram and the piston is temporarily connected with ambient air through the helical vent channel and a recess in the wall of the guide tube section after causing the impact on the tool bit.

Abstract: A piston apparatus which configures an air bearing by introducing a compressed working media into an inside of a piston, and ejecting the working media from plural holes arranged on a circumferential portion of the piston into a clearance between the piston and the cylinder, which prevents a back-flow of the working media in the piston to a working space, and which readily secures reliability and longevity is provided.

Abstract: Disclosed is a piston having a top chamfer functioning as an oil reservoir, the top chamfer designed to reduce piston noise and friction. The top chamfer partially defines a tapered volume or cavity configured to enhance oil flow to the middle portions of the piston skirt so as to increase lubrication during piston up stroke and thereby reduce piston noise and friction.

Abstract: A reciprocating compressor comprises: a cylinder having an oil pocket on an inner circumferential surface of a piston insertion hole for inserting a piston with a predetermined width and depth; and a piston having a bearing portion protruding so as to slidably contact an inner circumferential surface of the piston insertion hole, and inserted into the piston insertion hole of the cylinder, wherein the bearing portion is formed to have a length shorter than that of the oil pocket of the cylinder. Accordingly, a frictional loss between the cylinder and the piston is reduced.

Abstract: A piston has a pair of diametrically opposite skirt portions each having an opening providing fluid communication between an outer surface of the skirt portions and an internal cavity. The openings provide the outer surfaces of the skirt portions with a circumferentially extending upper band portion above a horizontal plane extending through a pin bore axis and a circumferentially extending lower band portion below the horizontal plane.

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 has a piston body with a pair of pin bosses having pin bores aligned along a central axis. The pin bores have bearing surfaces, wherein at least one recess extends axially across at least one of the bearing surfaces. A groove extends partially about the bearing surface circumference and is arranged in fluid communication with the recess. The recess and groove provide a lubrication feature to the pin bore, while the bearing surface has an uninterrupted portion for enhanced load carrying capacity.

Abstract: The invention concerns a piston compressor, particularly a hermetically enclosed refrigerant compressor, with at least one cylinder a piston reciprocating in said cylinder, the piston being connected with a driving rod via a piston pin and having in its outer jacket surface a circumferential lubrication groove, the piston pin having a longitudinal bore, which is connected with a lubricant source. It is endeavoured to improve the lubrication. For this purpose, the longitudinal bore is open downward in the gravity direction and has a ventilation opening upward.

Abstract: A piston for internal combustion engine, compressor or the like, includes a piston ring, a piston skirt having a piston skirt wall. One or more lubricant channels and reservoirs are provided on an outer surface of the piston skirt. Lubricant is conducted to an outer surface of a piston skirt of a piston through the lubricant channels which are communicating an inner surface of the piston skirt with the outer surface thereof. The lubricant is able to be reserved in the lubricant reservoirs provided on the outer surface of the piston skirt to maintain lubrication between the piston skirt and cylinder wall so as to reduce a friction between the cylinder and the piston skirt, reduce loss of power due to friction and heat, improve the output power, reduce the fuel consuming, noise and exhaust, and achieve fuel saving and environment protection.

Abstract: A piston for an internal combustion engine, the piston having a skirt part, comprises: a resinous coating layer formed on a surface of the skirt part; and a plurality of concaves regularly arranged in the resinous coating layer. The concaves are non-coated regions in which said resinous coating layer is not formed.

Abstract: In an internal combustion engine for a motor vehicle, having a piston bearing surface divided into regions of different loading and having recesses for retaining lubricant arranged at distances which are shorter in regions of high loading than in regions of lower loading in a region with high loading, the distance between the recesses decreases from one recess to the next in the direction toward top dead center area with the smallest distance being at the top dead center position of the piston.

Abstract: A monobloc piston assembly has at least two parts fixedly joined together forming a piston body having an oil cooling gallery. The oil cooling gallery is defined by an upper wall, a lower wall, and a pair of radially spaced inner and outer annular walls. A skirt is formed as one piece and of the same material with at least one of the two parts and depends generally along a longitudinal axis from the lower wall. A pair of pin bosses are spaced laterally from the longitudinal axis and depend generally from the lower wall. At least one elongated opening extends generally between the pin bosses with the opening preferably spanning a substantial portion of the distance between the pin bosses. Oil flows into and out of an oil cooling gallery through the opening.

Abstract: The invention concerns a piston arrangement having a piston with a piston head and a piston skirt with a circumferential surface, and a connecting rod, which is connected with the piston via a ball joint comprising a ball, and penetrated by an oil supply channel, which is connected with a bearing surface of the ball joint.

Abstract: A compressor is provided for guiding lubricating oil separated from the discharged refrigerant by an oil separator to a radial bearing supporting a drive shaft through an oil supply hole. A rotating member that rotates together with the drive shaft is provided adjacent to the radial bearing on the drive shaft, and lubricating oil is supplied to the radial bearing via a gap between an external surface of the rotating member and an internal surface of a circular hole that supports the rotating member. An oil support groove, which alternately communicates with the oil supply hole and the discharge hole every time the rotating member rotates once, is provided on the external surface of the rotating member, and the lubricating oil flowing in from the oil supply hole is intermittently discharged into a drive chamber via the groove and the discharge hole.

Abstract: A reciprocable piston comprises a cylindrical body reciprocable within a hollow cylinder and at least two spaced ring seals disposed around the circumference of the cylindrical body. Within the cylindrical body there is a scavenging system that comprises: an internal chamber that is in fluid communication with a space between the spaced ring seals; and a one-way fluid passage that allows one-way fluid flow from the internal chamber to the cylinder chamber when fluid pressure within the internal chamber is greater than fluid pressure within the cylinder chamber. A method of scavenging fluid comprises collecting fluid that leaks by a piston seal and returning the collected fluid to the cylinder chamber from which it originated, through a scavenging system disposed within the piston.

Abstract: A piston (6) of a piston pump unit (2), which can be displaced in a translatory manner, is guided in a cylinder bore (7). The piston (6) is driven by a crank drive (13) comprising an eccentric element (15) which is arranged on a drive shaft (14). A stroke ring (12) is rotationally mounted on the eccentric element (15) but does not rotate therewith. A sliding surface (10) of the piston (6) is arranged on a sliding bearing surface (11) on the stroke ring (12). A discharge chamber (22) is embodied inside the piston (6) on an end opposite the stroke ring (12). Said discharge chamber is open towards the sliding bearing surface (11). The discharge chamber (22) is connected in a pressure-wise manner to a working chamber (8) by means of a passage (23) in the piston (6). A displaceable control piston (25) is guided in a longitudinal bore (24) pertaining to said passage (23).

Abstract: An internal combustion engine includes at least one cylinder block having at least one combustion cylinder. A number of cylinder liners are respectively associated with each combustion cylinder. Each cylinder liner defines a corresponding cylinder inside surface. Each cylinder liner includes a plurality of discrete oil retaining indentations in a predefined pattern on the cylinder inside surface. The plurality of oil retaining indentations are bounded in both peripheral and longitudinal directions of the corresponding cylinder liner.

Abstract: The invention relates to the surfaces of the polygon (2) and/or the plunger foot plate (3) of a high-pressure pump for a diesel motor, at least one of the surfaces having cavities at least in the contact area between the polygon (2) and the plunger foot plate (3). According to the invention the face of the plunger foot plate (3) lying opposite the polygon (2) is concave, at least in the load-free state and the cavities have a depth of between 5 and 50 ?m, a width of between 30 and 100 ?m and a length of at least 100 ?m, or a diameter ranging between 30 and 100 ?m. The edges of the cavities are rounded. The invention also relates to a method for producing said surfaces, according to which the cavities are first created in the surface by means of chemical etching, blasting using blasting agents or by means of a laser removal process, the surface is subsequently polished in a vibratory grinding process and the edges of the cavities are rounded.

Abstract: A monobloc piston assembly has at least two parts fixedly joined together forming a piston body having an oil cooling gallery. The oil cooling gallery is defined by an upper wall, a lower wall, and a pair of radially spaced inner and outer annular walls. A skirt is formed as one piece and of the same material with at least one of the two parts and depends generally along a longitudinal axis from the lower wall. A pair of pin bosses are spaced laterally from the longitudinal axis and depend generally from the lower wall. At least one elongated opening extends generally between the pin bosses with the opening preferably spanning a substantial portion of the distance between the pin bosses. Oil flows into and out of an oil cooling gallery through the opening.

Abstract: A piston for use in internal combustion engines or reciprocating compressors such as those utilized in air-brake systems for heavy duty freight vehicles. The body of the piston of the present invention is contoured in manner to reduce the undesirable build-up of oil pressure that frequently occurs at the oil control ring or rings when the piston is in operation. The crown portion of the piston body includes a series of piston ring groove and piston ring lands, one of which is modified to include drainage notches. The skirt portion of the piston body includes a plurality of furrows near the face of the piston, a horizontal channel recessed into the surface of the piston skirt, and a horizontal groove formed in the outer skirt wall of the piston. These structures function individually and in combination to provide multiple means by which excess lubricating oil may be directed away from the oil control rings and back toward the crankcase or oil reservoir within the engine or compressor.

Abstract: A method and device for forming a sliding seal between a reciprocating piston (22) and the wall of a cylinder (8), wherein one side of the piston faces a first liquid in a pump chamber (26) of the cylinder (8), a first piston seal (24) and a second piston seal (58), spaced from the first piston seal (24), sealing between the piston and the cylinder (8); and wherein a second liquid is supplied under pressure between the seals (24, 58), the pressure of the second liquid between the seals (24, 58) being maintained at a level essentially equal to or slightly lower than the pressure of the pump chamber (26).

Abstract: The invention relates to a method for producing a ring support (1) with a sheet metal cooling channel welded thereon (5), which is transfused later with an aluminium melt for producing a piston. The aim of the invention is to improve the production of openings (4) for supplying and removing oil. Said openings are produced even before the transfusion of the cooled ring support. When the alfin pretreament of the cooling ring supports occurs, said cooling channel is filled with melt and emptied again during removal front the alfin bath.

Abstract: An in-line lubricator for a pneumatic tool system includes a body defining a fluid reservoir and a working passageway and an actuator positionable within the body. The actuator includes an elongated body having a transfer cavity formed therein which is in fluid communication with the fluid reservoir when the actuator is in a first position and which is in fluid communication with the working passageway when the actuator is in the second position. Movement of the actuator from the first position to the second position transports a predetermined amount of fluid from the fluid reservoir into the working passageway.

Abstract: A piston for use in a compressor comprises a head portion and an engaging portion. The engaging portion includes a first shoe pocket and a second shoe pocket formed therein, and an interior surface of the first shoe pocket includes a hollow potion formed therein. Moreover, the interior surface of the first shoe pocket includes a lubrication layer formed thereon. For example, the lubricant layer may include a solid lubricant or a grease having a viscosity which is sufficient to adhere the grease to the interior surface of the first shoe pocket or the second shoe pocket, or both. In an embodiment, an interior surface of the second shoe pocket also may have the hollow portion formed therein. In another embodiment, the interior surface of the second shoe pocket may have a penetrating aperture formed therein.

Abstract: An internal combustion engine for enhancing a heat radiation property of combustion gas, can sufficiently secure strength thereof relative to combustion gas, and a weight reduction thereof can be realized. A piston for an internal combustion engine is constituted of a head part, a cylindrical skirt part extending from a lower part of the head part. A pair of pin boss parts are formed on both opposing side walls to each other of the skirt part. A plurality of recessed parts, the cross sections thereof being presented as smooth circular arcs, are formed on a surface on an opposing side to a surface facing to a combustion chamber of the head part, that is, to a reverse face.

Abstract: In order to increase in concentration of HC in an exhaust gas due to an axial gap between a ring groove and a piston ring, when an internal combustion engine is at a lower temperature, particularly, during the starting or the low-speed operation of the internal combustion engine in which the moving speed of a piston is lower, a restricting ring having a radially outward tension is inserted in a wedge shape into between axially opposed surfaces of a ring groove and a piston ring so that in a lower-speed operational range of a piston, the axial movement of the piston ring within the ring groove is restricted by the wedging action of the restricting ring, and in a higher-speed operational range of the piston, the wedging action of the restricting ring is removed by a floating force of the piston ring generated with the descending movement of the piston.