Abstract: An internal combustion engine includes in one aspect a source of a pressurized working medium and an expander. The expander has a housing and a piston, movably mounted within and with respect to the housing, to perform one of rotation and reciprocation, each complete rotation or reciprocation defining at least a part of a cycle of the engine. The expander also includes a septum, mounted within the housing and movable with respect to the housing and the piston so as to define in conjunction therewith, over first and second angular ranges of the cycle, a working chamber that is isolated from an intake port and an exhaust port. Combustion occurs at least over the first angular range of the cycle to provide heat to the working medium and so as to increase its pressure.

Abstract: A piston for an internal combustion engine has a piston head and a piston skirt spaced apart from the piston head by a ring-shaped recess. The piston has at least one pin bore for accommodating a piston pin. A ring-shaped circumferential cooling channel for a coolant is provided in the piston head, which channel is closed off by a cover ring that consists of at least two segments. At least one region of the cover ring projects at least partially into the clear opening of the at least one pin bore, in such a manner that the cover ring simultaneously forms the retaining element for the piston pin.

Abstract: Disclosed is a piston (1) for a combustion engine, comprising an annular grooved reinforcement (4) that is screwed onto an externally threaded (13) collar (12) located in the piston head area via an internal thread (19) which is mounted on the inside of the grooved reinforcement (4). The grooved reinforcement (4) blocks a recess (14) so as to form an annular, closed cooling duct (21). In order to provide the screwed connection between the collar (12) and the grooved reinforcement (4) with sufficient stability, a radially outward area of the collar (12) is equipped with a bend that points towards the hub. Furthermore, the collar (12) is embodied in an elastically resilient manner so as to bend in the direction of the piston head when the grooved reinforcement is screwed in, thus prestressing the screwed connection.

Abstract: A multi-part piston for a combustion engine having a piston upper part and a piston lower part, where the piston upper part has a piston crown and an attachment head on its side facing the piston lower part, and the piston lower part has an attachment element in which the attachment head is held, the attachment element being disposed on a side facing the piston upper part. The attachment head is held in the attachment element by a press fit.

Abstract: A method of producing a piston that involves providing a piston body formed of a first material, the piston body having a cylindrical portion having a diameter, a rounded end, and a neck connecting the rounded end to the cylindrical portion and having a diameter less than the diameter of the piston body, cladding a portion of the cylindrical portion with a first tool steel layer, cladding a portion of the rounded end with a second tool steel layer spaced from the first tool steel layer, heat treating the piston body and nitriding the first and second tool steel layers. Also a piston (10) having first (18) and second (22) nitrided, tool steel clad portions.

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 diesel engine piston assembly comprises a piston body having a top wall with a combustion bowl formed in the top wall and having a combustion bowl edge, an outer ring belt formed with a plurality of ring grooves including a top ring groove with an upper wall of the top ring groove and a top land portion of the ring belt disposed between the top ring groove and the top wall, a pair of pin bosses with aligned pin bores and a skirt; and a diamond dispersed chromium composite coating applied to at least the top wall, the combustion bowl edge, the top land portion and the upper wall of the top ring groove.

Abstract: Carbon deposits on engine components can negatively affect engine performance. An engine of the present disclosure includes at least one carbon deposit resistant engine component attached to an engine housing. The engine component includes at least one relatively high surface tension surface that is a non-contact wear surface and to which a relatively low surface tension coating is attached. The relatively low surface tension coating has a surface tension at least one of equal to and less than 30 dyne/cm.

Abstract: A piston head has a top extending radially about a first axis and first and second pin bosses depending downwardly and defining first and second pin bores. A connecting rod includes a fork having first and second connecting bosses spaced apart from each other and defining first and second connecting bores. A piston skirt extends cylindrically and includes a bridge extending diametrically through the first axis defining a skirt bore for axial alignment with said pin bores and said connecting bores. The bridge is disposed between the first and second connecting bosses, which are disposed between the pin bosses. The pin bores are axially aligned with the connecting bores and with the skirt bore. A wrist pin extends within the pin bores and the connecting bores and the skirt bore along the second axis to interconnect the piston head and the connecting rod and the piston skirt.

Abstract: A structure of a chamber in a combustion engine includes a ring-groove portion formed on the piston, a squish-area making portion formed on a top surface of the piston for a squish-area, an outer edge portion formed around the top surface excepting the squish-area making portion, and a land portion formed around a side surface between the ring-groove portion and the top surface. The land portion includes, a squish-land portion formed between the ring-groove portion and the squish-area making portion, an outer-edge-land portion formed between the ring-groove portion and said outer edge portion, the outer-land portion being smaller than the squish-land portion in height.

Abstract: A piston and method of making a piston which involves providing a single piece piston blank that, after casting or forging, is separated into separate upper and lower portions. The upper portion is machined to develop a piston head having that includes a cooling gallery portion and the lower portion is machined to develop a piston body having a cooling gallery portion, a skirt and a pair of opposed pin bores. After machining the piston head and piston body are attached together and the resulting assembly is machine finished into a finished piston.

Abstract: Disclosed is a multipart, cooled piston for a combustion engine, comprising, in a radially outward direction, an annular cooling duct located on the bottom side that faces away from the piston head. The cooling duct is closed by a cooling duct cover which is embodied as a ring. The cooling duct cover is provided with a tongue in the radially inner zone. The tongue engages into a recess that is molded into the bottom piston part, thus preventing the cooling duct cover from rotating relative to the piston during assembly as well as during operation.

Abstract: Disclosed is a two-part piston (1) for a combustion engine comprising a combustion chamber (16) in the piston head (13). The piston (1) is composed of a basic member (5) and a top part (6) that is screwed to the basic member (5). In order for the combustion pressure to act substantially upon the basic member (5), which is provided with great mechanical stability and load-bearing capacity relative to the pressure prevailing in the combustion chamber, the bottom part of the combustion chamber (16) is molded into the basic member (5), the top part (6) is configured in an essentially annular manner, and the top part (6) enlarges the combustion chamber (16) at the piston head end while delimiting the same in a radially outward direction similar to a collar (19).

Abstract: Disclosed is a piston (1) for a combustion engine comprising a closed ring element (6) which is disposed in the radially outer peripheral area of the piston head (5) and is joined to the basic piston member (4) by means of a high-temperature resistant adhesive. The basic member (4) is made of forged aluminum while the ring element (6) is made of Ni-resist. A closed, annular cooling duct (15) that comprises holes for delivering and discharging cooling oil is placed between the basic member (4) and the ring element (6), resulting in a piston (1) that has a simple design, can be produced at low cost, and can be subjected to great thermal loads.

Abstract: Otto cycle internal combustion engine, comprising a cylinder block including at least one cylinder having a longitudinal axis, a piston movable within said cylinder and having a recess open on a head surface of the piston, a head fastened to said cylinder block and having a surface facing the cylinder, three intake valves and two exhaust valves movable along respective rectilinear directions, a combustion chamber delimited at one side by a portion of the surface of the head facing the cylinder and, at the other side, by the surface of said recess of the piston. The directions of motion of the valves are parallel to each other, the surface of the head facing the cylinder is planar and orthogonal to the directions of motion of the valves and the combustion chamber is obtained exclusively in the piston.

Abstract: An optimized two-stroke internal combustion diesel engine, suitable for locomotive applications, has been developed to meet the EPA locomotive Tier 2 emission standards. To achieve a low emission target below the EPA Tier 2 standards for NOx (5.5 g/bhp-hr) and particulates (0.2 g/bhp-hr), several innovative changes have been made to the engine. These changes include: a new piston bowl geometry; low oil consumption piston rings; optimized surface finish cylinder liner; optimized fuel injection camlobe; modified fuel injector nozzle; new efficient aftercooler; optimized oil separator; and optimized turbocharger.

Abstract: The present invention relates to a method of production of functionally graded materials based on an incremental melting and solidification process. Its operation principle can be described as follows: the materials (metal elements, alloys or ceramics) are melt by the induction heating in the mould, and the continual granules, powders or wire, or even liquid materials, of another metal alloys are fed to the mould. The heating zone is limited to a small part of the mould. The incremental melting and solidification process proceeds from the bottom to the top of the mould by changing the relative position between the mould and the heating apparatus. Usage of this method ensures the obtainment of components with no particular alloy composition, but with a gradual changing of the chemical composition along the casting.

Abstract: A ceramic engine cylinder assembly of a car comprises a cylinder and a piston. A layer of ceramic material is coated on an inner surface of the cylinder; similarly, a layer of ceramic material is coated on an outer surface of the piston. When the piston is moving in the inner surface of the cylinder reciprocately, which can produce better lubricating effects so as to reduce the friction resistance and increase the power of the engine.

Abstract: An engine piston is manufactured by assembling an outer shell, comprising a crown and tubular side wall in which a ring groove region and skirt are defined, with a plate-like mounting member and bonding them together by brazing or welding. The mounting member is located within the tubular side wall displaced axially from the crown and is bonded near, but displaced radially from, its centre to the crown and at its periphery to the side wall at the end of the ring groove region. The mounting member carries gudgeon pin boss means facing away from the crown. The outer shell is formed by extrusion or the like that permits minimal wall thickness and the bonded structure is of light weight but great strength and stiffness, particularly in the ring groove region. A combustion bowl formed in the crown facilitates bonding to the mounting member and defines with the mounting member an annular cooling chamber adjacent the ring groove region and crown.

Abstract: A squish surface having the shape of a plane surface orthogonal to the axis of a piston is formed on the intake side of the piston top surface. A squish area is formed between the squish surface and a plane surface-shaped squish surface on the cylinder head side, and at the same time, a squish guide surface is formed in the piston top surface so as to be continuously ridged from the squish surface toward the vicinity of a spark plug.

Abstract: A piston includes a spring acting between the piston crown and a connecting rod so as to bias the connecting rod away from the crown of the piston. The spring may include a pair of disc springs supported at their edge portions. The support may be a substantially annular support including a pair of rings fixed to the edge portions of the disc springs and an annular band that engages the rings and permits relative movement between the band and the rings.

Abstract: A piston for an internal combustion engine has an upper crown with a top and a bottom surface, and a lower crown with a top and a bottom surface. The upper crown and the lower crown are fixedly attached to each other using welds, with the bottom surface of the upper crown and the top surface of the lower crown forming a mating surface. The piston also has at least one centrally located air gap formed on the mating surface. The air gap is sealed to prevent substantial airflow into or out of the air gap.

Abstract: A piston includes: in a cross-section that is perpendicular to a piston pin and that includes a center axis of the piston, a great thickness-reduction portion provided to attain a thin thickness as stress applied to the piston on a side without a cavity is small, and a small thickness-reduction portion provided to attain a thick thickness as stress applied to the piston on a side with the cavity is great; and in a cross-section that is perpendicular to the piston pin and that does not include a center axis of the piston, a great thickness-reduction portion provided on a side without the cavity to attain a thin thickness to achieve balance of the piston, and a small thickness-reduction portion provided on a side with the cavity.

Abstract: A method for surface treatment capable of easily improving a mechanical strength of an internal combustion piston at a reasonable cost is provided. A modified surface layer is formed by injecting injection powders containing a reinforcing element to be collided with an Al—Si alloy-based piston obtained by casting and forging by injecting under predetermined conditions, the reinforcing element being diffused and penetrated in the piston to improve the strength thereof. When a function, such as fuel modification, is imparted to the modified surface layer, an element exhibiting a photocatalytic function by oxidation, such as Ti, Sn, Zn, Zr, or W, is selected as the reinforcing element.

Abstract: A piston ring is provided having a first axially facing surface and a second axially facing surface. At least one of the first and second axially facing surfaces has a friction reducing surface treatment. The friction reducing surface treatment is preferably formed from tungsten disulfide. Additionally, a method of forming a low friction piston ring is provided including applying a friction reducing surface treatment, such as tungsten disulfide, to at least one of the first and second axially facing surfaces and preventing the application of the friction reducing surface treatment on the radially outwardly facing surface. An internal combustion engine incorporating the disclosed piston ring is also provided.

Abstract: The invention relates to a split piston for an internal combustion engine, comprising an upper piece, connected to a lower piece, by means of a screw connection. The screw connection comprises a tubular connector piece, mounted on the underside of the piston upper piece with an external thread, a spacer sleeve with an external and an internal thread and a support rib formed on the lower piece of the piston with an internal thread. The upper piece can thus be screwed to the lower piece, by means of the connector piece, the spacer sleeve and the support rib. The spacer sleeve acts as a compressing body and the connector piece as an extending body, to generate the mechanism tension necessary for fixing the screw connection.

Abstract: The present invention relates to a piston (10, 110) for a combustion engine having a basic element (11, 111) and a ring carrier element (12, 112) held on the basic element (11, 111) with a top land (25, 125) all around its circumference and ring belt (26, 126) all around its circumference. It is provided in accordance with the invention that the ring carrier element (12, 112) grips around the basic element (11, 111) at least partially and is held on the basic element (11, 111) by means of a press fit.

Abstract: The invention relates to a piston for an internal combustion engine, which comprises two boss bores that have respective outer areas with an oval cross-section that points on one side in the direction of the piston head. The great axis of the ovality is parallel to the piston axis and the degree of ovality increases towards the outer end of the boss bores.

Abstract: Proposed is a two-part piston 1 for an internal combustion engine, having an upper part 2 that has a pin 31 having an outside thread 32 on the underside of its piston crown 4, and having a lower part 3, which is connected with the upper part 2 by means of a nut 29 screwed onto the pin 31. The lower part 3 has an elastically resilient upper base part 25, onto which an expansion sleeve 26, elastic in the axial direction, is formed, which has an opening 27 having a collar 28, which is directed radially inward, into which the pin 31 is introduced. An elastic compression sleeve 30 is formed onto the nut 29, which sleeve rests against the collar 28. In this connection, the elastic resilience of the base part 25, the expansion sleeve 26, the compression sleeve 30, the pin 31, and the piston crown 4 has the result that the screw connection has a flat characteristic line despite a low compression height of the piston 1, thereby imparting great strength to the screw connection.

Abstract: An engine is cooled using high pressure water injected into the piston with the water converted to high pressure steam by the heat from combustion with heat transfer taking place in passages in the piston and in and between grooves in the piston and the cylinder sleeve. The high pressure steam is conducted between the piston and cylinder walls to lubricate, so there will be no need for piston rings, with a part of it passing into the crankcase, and a part of it going into the combustion chamber where it contributes to power production. The piston skirt has a spring-loaded washer access to a void in a lower passage for balancing pressures.

Abstract: A spherical coupling structure for a piston and a connecting rod, wherein a protrusion provided to the reverse side of a crown of a piston and a holding member for holding a small end are slidably fitted onto a small end, and a holding/fastening part for holding the protrusion and the holding member is screwed in. The piston is composed of an upper piston that includes the protrusion and a lower piston that includes the holding/fastening part. The masses of the upper piston and lower piston are distributed so as to substantially match each other.

Abstract: An improved piston ring suitable for use in an internal combustion engine is disclosed comprising a plurality of races sized to receive elongate rollers disposed around the circumference thereof. The elongate rollers may be shaped as a prolate ellipsoid or other rounded shape. The piston ring may seat within a groove in fluid communication with an oil channel extending through a piston rod and opening into a rod bearing connecting the piston rod to a crankshaft. A crankshaft has a corresponding oil channel therewith and has an opening positioned to periodically align with the opening in the rod bearing when rotated. Oil is pumped into the oil channel in the crankshaft to force oil over the piston rings. Drain apertures may be formed in another groove formed in the piston to conduct oil away from the piston.

Abstract: There is provided a structure for connecting a piston to a crankshaft in an internal combustion engine, including a piston pin fitted into the piston, a crankpin integral with the crankshaft and a connecting rod having a piston pin bearing portion slidably engaged with an outer cylindrical portion of the piston pin and a crankpin bearing portion slidably engaged with an outer cylindrical portion of the crankpin. At least one of the piston pin bearing portion of the connecting rod and the outer cylindrical portion of the piston pin and at least one of the crankpin bearing portion of the connecting rod and the outer cylindrical portion of the crankpin have hard carbon coatings formed thereon with a hydrogen content of 20 atomic % or less.

Abstract: Cylinder head assemblies including a cylinder head and a piston are disclosed. The cylinder head includes: a recessed valve region including a first and second bulbous portion connected by a waist, the first bulbous portion accommodating an intake valve and the second bulbous portion accommodating an exhaust valve; an intake port passageway having a gradually contoured flowpath between an intake port and the intake valve in the valve region; and an exhaust port passageway having a gradually contoured flowpath between an exhaust port and the exhaust valve in the valve region. The piston includes a recessed region that substantially conforms to the recessed valve region of the cylinder head. Related overhaul kits and methods of making improved cylinder head assemblies are further disclosed.

Abstract: The invention related to a piston-pin boss (18) of a piston (6) for an internal combustion engine, comprising a piston-pin bore (1) for receiving a piston pin. To improve the passage of oil and to form an oil reservoir, the interior surface (2) of the bore comprises a transversal groove (5) that lies parallel to the longitudinal axis (3) of the piston-bore (1) and opens towards the exterior of the piston and an oil circulation groove (4) that intersects the transversal groove (5) and encircles the longitudinal axis (3).

Abstract: This invention produces a variable compression ratio in internal combustion engines, based on a sliding concentric piston which moves up by an internal spring and down by the different changing pressures over the concentric piston head, within the combustion chamber. This invention changes the compression ratio in an instantaneous and continuous way, depending directly on the pressure of the fuel mixture load in the combustion chamber.

Abstract: A two stroke engine of a particular configuration can have its power output increased by running bigger pistons and using ports in the piston skirt through which to conduct compressed air within the skirt through short passages in the cylinder housing that conduct the air from within the skirt to above the piston. As a result a larger piston can be used for the same spacing and opening size in the block to save the need to redesign the block and the crankshaft. A position adjuster for the piston moves it axially without rotation of the piston ports out of alignment with inlet ports in the housing. The piston rod is held in the crosshead using a flat to prevent rotation while an adjuster nut that is turned creates axial movement in the piston rod with a lock nut securing the final piston position.

Abstract: A piston for an internal combustion motor has a skirt with a surface, which is at least partially polished and thereafter coated with a coating having a hardness of greater than 8 GPa and having a coefficient of friction of less than 0.20. The piston has an increased performance, a longer lifetime and a reduced friction.

Abstract: A piston for an internal combustion engine includes a crown part, a land part extending from the crown part, a skirt part adjoining the land part, and a linking boss protruding from a reverse surface of the crown part and forming a spherical joint with a small end of a connecting rod. The piston is divided into an upper piston part having the land part, and a lower piston part having the skirt part and a plurality of molded plate members formed by press-molding plates.

Abstract: Proposed is a two-part piston 1 for an internal combustion engine, having an upper part 2 that has a pin 31 having an outside thread 32 on the underside of its piston crown 4, and having a lower part 3, which is connected with the upper part 2 by means of a nut 29 screwed onto the pin 31. The lower part 3 has an elastically resilient upper base part 25, onto which an expansion sleeve 26, elastic in the axial direction, is formed, which has an opening 27 having a collar 28, which is directed radially inward, into which the pin 31 is introduced. An elastic compression sleeve 30 is formed onto the nut 29, which sleeve rests against the collar 28. In this connection, the elastic resilience of the base part 25, the expansion sleeve 26, the compression sleeve 30, the pin 31, and the piston crown 4 has the result that the screw connection has a flat characteristic line despite a low compression height of the piston 1, thereby imparting great strength to the screw connection.

Abstract: The invention relates to a piston for internal combustion engines comprising a lower part which forms the shaft area and also comprising a piston upper part which is connected thereto by means of expandable screws and which forms the bottom and a ring area wherein the expanding screws in the piston upper part (1) are disposed on pressure pieces engaging in the respective bores in the lower piston part (1) and wherein the respective disposition between the pressure piece and the lower piston part (1) occurs via inclined adjacent surfaces. The aim of the invention is to invent a piston which is easy to produce, which in relation to prior art enables improved introduction of forces for the connection of the piston part to the piston.

Abstract: An obstruction is employed in a combustion chamber of an internal combustion engine. The obstruction is located within the chamber to generate turbulence and break-up or disrupt the soot rich zone within a directly injected quantity of fuel that is burning. More specifically, a ring disrupts fuel jets directly injected into the combustion chamber that impact on or are influence by the ring. The ring can be suspended from the piston or from the fire deck. Post-type obstructions help generate turbulence and are also targeted at disrupting the soot rich zone of the burning fuel jets. A method involves disrupting the soot rich zone or reducing soot generated within the combustion chamber and increasing burn rate by impacting the fuel jets on an obstruction within the chamber.

Abstract: The invention relates to a piston (1), which is comprised of an approximately circular cylindrical upper area (5) and of a lower area (6), having two hubs (7), which are set back toward the piston central axis (8) so that, in the upper area (5), recesses (12, 12?) can be made, which are open toward the lower area (6), in the vicinity of the hubs (7). In order to make relief cuts (13, 13?) in the area between the hubs (7) and the upper area (5), a salt mold part (15) is placed on the respective window insert (14). The salt mold part (15) serves to produce the recesses (12, 12?) as well as the relief cuts (13, 13?) when casting the piston (1) and is washed out after the piston (1) has been cast.

Abstract: A method and apparatus for lowering NOx in diesel engine exhaust gases while maintaining thermal efficiency, by retarding the start of fuel injection, increasing the compression ratio, and reducing the turbocharger inlet flow area to increase turbocharger speed and inlet manifold boost levels for the engine intake air.

Abstract: A two-part piston for an internal combustion engine, comprising a piston head and a piston skirt connected with the piston head in articulated manner, by way of a piston pin. The piston head has a piston crown that is followed by a cylindrical circumference surface having a top land and a ring belt. The piston head can include a ring-shaped circumferential cooling channel disposed within the piston head. The opening of this cooling channel faces the piston skirt, and is closed off with a seal element. There is a seal element that has a first free end that is held between piston head and piston skirt, or rests against an outer wall of the cooling channel. The seal element has a second free end that rests against the piston head, and wherein the seal element has a bottom that lies on a surface of the piston skirt that faces the cooling channel.

Abstract: The invention relates to a piston for an internal combustion engine comprising piston-pin bores, into which lubrication grooves that run around the nadir and equator zones of said bores are machined. The aim of the invention, is to simplify the production of the piston-pin bores provided with said lubrication grooves. To achieve this, each of the lubrication grooves has a central region, whose groove base has a depth of less than 100 ?m. Said central region is flanked by groove areas facing towards the interior and exterior of the piston. The bases of said grooves are inclined towards the longitudinal axis, each forming an acute angle with the longitudinal axis of the piston-pin bore.

Abstract: A pivoted piston for an internal combustion engine. The piston has a pivot pin and an arcuate first sealing surface (12) which describes a circumferential path about the pivot pin which forms a removable and replaceable skirt to the piston. The piston also includes a second arcuate sealing surface which also describes a circumferential path about the pivot pin and which is connected to the first arcuate sealing surface (12) by a piston floor (21). The second arcuate sealing surface is composed of at least two arcuate sealing components (24) which are located on a bed (20) with the components (24) being located on the bed (20) so they will have limited transverse movement on the bed (20). The components (24) have mating faces which restrict the path of combustion gases between the mating faces. The piston further includes side seals which are located in grooves (63) in the side of the piston.

Abstract: The invention relates to a cooled piston (1) for an internal combustion engine comprising a cooling duct (2). This cooling duct encircles in an annular manner inside the piston head at the height of the ring part and is closed at its end, which is open toward the piston skirt, by men of a spring part (8). Said spring part is correspondingly shaped, is radially divided at least once on the periphery thereof, and provided with a cooling oil inlet (5). The aim of the invention is to achieve an improved location-dependent removal of heat from the particularly hot portions of the piston (1). To this end, an encircling oil guiding ring (3) is placed inside the cooling duct (2) and, from the cooling oil inlet (5) to the cooling oil outlet (6), symmetrically divides the cooling duct (2) on the periphery thereof into sections (4) of different cooling duct volumes.

Abstract: A combustion chamber (20) opening toward a cylinder head (5) is provided on a top surface (11) of a piston (10), and this combustion chamber (20) comprises a first volume (22) having an inclined surface (20) and a second volume (23) further recessed from the first volume (22) toward a pin boss (13). Fuel spray F from a fuel injection nozzle (9) is injected toward an inner peripheral wall section (24) of the second volume (23) in a former stage of fuel injection and toward the inclined surface (21) of the first volume (22) in a later stage of fuel injection, and the percentage of the fuel injection period in the former stage against the total fuel injection period is set to the range from 40% to 70%.

Abstract: A method of forming a low-friction, helically ridged skirt surface of an engine piston comprises cutting a continuous groove in a piston body rotating about axis so that adjacent groove turns intersect as ridges and carry lubricating oil which forms a film on the ridged surface. The groove is cut by way of a diamond tool tip traversing along the axis. Whereas in a known, standard finish, the ridges have sharp peaks that can rupture the oil film, the tool is here modified to include a planing tip fixed spatially with respect to the tip so that after formation each ridge is planed flat to provide a plateau between groove turns that exerts less film rupturing pressure against a cylinder wall while defining a uniformly flat outer surface for the piston. The cutting may vary the piston diameter toward the ends of the body to effect barreling in which the relationship between plateau width and groove depth vary.