COOLING MEMBER FOR ROTATING ELECTRICAL MACHINE, ROTATING ELECTRICAL MACHINE, AND METHOD FOR MANUFACTURING COOLING MEMBER FOR ROTATING ELECTRICAL MACHINE
A cooling member for a rotating electrical machine includes: a first portion forming a cooling medium inlet hole; a second portion forming a cooling medium outlet hole; and a third portion forming a cooling medium passage that connects the cooling medium inlet hole and the cooling medium outlet hole without communicating with outside. The third portion includes, in the cooling medium passage, a plurality of first pillar portions each standing in a first direction perpendicular to a flow of a cooling medium, and a plurality of protruding portions each protruding in the first direction. The cooling medium is in contact with surfaces of the plurality of first pillar portions and surfaces of the protruding portions that are exposed to the cooling medium passage.
Provided is a heat shielding film that is free from release or the like even where the heat shielding film is formed on a top surface of a piston and used in a severe environment such as the inside of an engine combustion chamber, and a vehicular heat shielding component on which the heat shielding film is formed. The vehicular heat shielding component of the present invention is one in which a heat shielding film (1) is formed on at least a part of the surface of a heat shielding target component (2) such as a piston of an engine to be given heat shielding properties. The heat shielding film (1) contains at least an inorganic compound layer (10) having a Vickers hardness (HV) of 50 to 100 in which one or a plurality of types of scale-like inorganic particles (12) selected from a group comprising mica, talc, and wollastonite are dispersed in an inorganic compound (11) formed of an alkoxide. By burning the inorganic compound layer (10) through irradiation of light having a wavelength of 500 nm or less, it is possible to increase the hardness of the inorganic compound layer (10) to 50 to 100 HV described above while suppressing an increase in temperature of the heat shielding target component (2).
B60R 13/08 - Insulating elements, e.g. for sound insulation
C25D 11/08 - Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids
B05D 7/14 - Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
B05D 3/06 - Pretreatment of surfaces to which liquids or other fluent materials are to be appliedAfter-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
3.
MANUFACTURING METHOD OF COOLING MEMBER FOR ROTARY ELECTRIC MACHINE
A manufacturing method of a cooling member to be used for a rotary electric machine. The manufacturing method includes a preparation step for preparing a plurality of annular collapsible cores having radial projections and recesses, a stacking step for concentrically stacking the plurality of collapsible cores along a direction of extension of a rotational axis of the rotary electric machine, a casting step for pouring a material of the cooling member into a die with the plurality of collapsible cores stacked in the die so that the material covers outer peripheral surfaces and inner peripheral surfaces of the plurality of collapsible cores, and a removal step for removing the plurality of collapsible cores after the casting step.
H02K 15/02 - Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
H02K 1/32 - Rotating parts of the magnetic circuit with channels or ducts for flow of cooling medium
B22C 9/24 - Moulds for peculiarly-shaped castings for hollow articles
B22C 9/10 - CoresManufacture or installation of cores
B22D 25/02 - Special casting characterised by the nature of the product by its peculiarity of shapeSpecial casting characterised by the nature of the product of works of art
4.
METHOD OF MANUFACTURING STATOR FOR ROTARY ELECTRIC MACHINE
A method of manufacturing a stator for a rotary electric machine includes: a step of preparing a stator core formed from a first metal material that is magnetic, the stator core having a space provided on a radially inner side and in which a rotor is to be disposed; a blocking step of covering at least a part of an end surface of the stator core in an axial direction and blocking the space using a blocking member; and a casting step of pouring a second metal material that is non-magnetic to a radially outer side of the stator core with at least a part of the end surface of the stator core covered and with the space blocked through the blocking step in a die.
H02K 15/02 - Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
B22D 19/00 - Casting in, on, or around, objects which form part of the product
5.
COATING COMPOSITION FOR SLIDING MEMBER, AND SLIDING MEMBER
Provided is a coating composition for a sliding member, the coating composition being used for forming a coating on the surface of a sliding member. The coating composition contains a binder resin, a solid lubricant, and a wear-suppressing material. The coating composition contains 0.5-6 parts by weight of the solid lubricant and 5-30 parts by weight of the wear-suppressing material per 100 parts by weight of the binder resin. The solid lubricant is at least polytetrafluoroethylene. The wear-suppressing material is at least silica. The grain diameter ratio of the polytetrafluoroethylene and the silica, as calculated using (polytetrafluoroethylene/silica), is 0.8-80. The coating composition according to the present disclosure makes it possible to form a coating that can simultaneously fulfill all of low friction coefficient, high scorch resistance, high wear resistance, and low counterpart aggression while being a simple blend.
Provided is a heat insulating film which, despite being provided with an inorganic compound layer, overcomes various problems that arise due to the occurrence of voids or microcracks in the inorganic compound layer. A heat insulating film (10) formed on at least a portion of the surface of a component 2 to be heat-insulated is formed from: an inorganic compound layer 20 in which scaly inorganic particles 22 are dispersed in an inorganic compound 21 formed from an alkoxide; and a top coat 30 that is formed on the inorganic compound layer 20, has a thickness of 0.5-30 µm, and is formed by an organic-inorganic hybrid material comprising a mixture of a metal alkoxide and a resin. By the formation of the top coat 30, voids 23 or microcracks in the inorganic compound layer 20 are filled by the organic/inorganic hybrid material, and the surface of the inorganic compound layer 20 is covered, whereby the heat insulating performance of the heat insulating film 10 is enhanced, and fuel efficiency of an engine is improved by forming the heat insulating film 10 on piston top surfaces of the engine.
B32B 9/00 - Layered products essentially comprising a particular substance not covered by groups
C23C 28/00 - Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of main groups , or by combinations of methods provided for in subclasses and
F16J 9/26 - Piston-rings, seats thereforRing sealings of similar construction in general characterised by the use of particular materials
A cooling member for a rotating electric machine is disclosed. The cooling member comprises a first location forming a refrigerant inlet, a second location forming a refrigerant outlet, and a third location forming a refrigerant path communicating between the refrigerant inlet and the refrigerant outlet without providing external communication. The third location comprises, in the refrigerant path, a plurality of first column portions each extending upright in a first direction perpendicular to the flow of refrigerant, and a plurality of projections each projecting in the first direction. The refrigerant contacts the surfaces of the plurality of first column portions and the surfaces of the plurality of projections exposed in the refrigerant path.
Disclosed is a rotating electrical machine stator for driving a vehicle, the rotating electrical machine stator comprising: a stator core that is formed from a first metal material which is a magnetic body; a bonding layer that is formed on at least part of the outer circumferential surface of the stator core and includes a second metal material which is a non-magnetic body; and a stator support that is integrally bonded to the outer circumferential surface of the stator core and is formed from the second metal material. The stator core has, in a first section on a circumferential-direction part of the axial end of the outer circumferential surface, a recess that is recessed further radially inward than a second section and that extends in the axial direction. The stator support is located on the outer circumferential edge of the axial end surface of the stator core in the circumferential-direction second section, and is located inside the recess in the circumferential-direction first section.
H02K 1/18 - Means for mounting or fastening magnetic stationary parts on to, or to, the stator structures
H02K 1/20 - Stationary parts of the magnetic circuit with channels or ducts for flow of cooling medium
H02K 15/02 - Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
A rotating electrical machine for vehicle driving that includes a stator core made of a first metal material which is a magnetic material; and a case part that is integrally joined to the stator core and made of a second metal material which is a non-magnetic material, and a joint surface between the case part and the stator core forms a heat receiving surface where the case part receives heat from the stator core.
H02K 5/02 - Casings or enclosures characterised by the material thereof
H02K 15/02 - Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
Provided is a heat shielding film that is free from release or the like even where the heat shielding film is formed on a top surface of a piston and used in a severe environment such as the inside of an engine combustion chamber, and a vehicular heat shielding component on which the heat shielding film is formed. The vehicular heat shielding component of the present invention is one in which a heat shielding film (1) is formed on at least a part of the surface of a heat shielding target component (2) such as a piston of an engine to be given heat shielding properties. The heat shielding film (1) contains at least an inorganic compound layer (10) having a Vickers hardness (HV) of 50 to 100 in which one or a plurality of types of scale-like inorganic particles (12) selected from a group comprising mica, talc, and wollastonite are dispersed in an inorganic compound (11) formed of an alkoxide. By burning the inorganic compound layer (10) through irradiation of light having a wavelength of 500 nm or less, it is possible to increase the hardness of the inorganic compound layer (10) to 50 to 100 HV described above while suppressing an increase in temperature of the heat shielding target component (2).
B32B 9/00 - Layered products essentially comprising a particular substance not covered by groups
C23C 28/04 - Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of main groups , or by combinations of methods provided for in subclasses and only coatings of inorganic non-metallic material
C25D 11/06 - Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
Disclosed is a method of manufacturing a cooling element utilized in rotating electrical machines, the manufacturing method comprising: a preparatory step of preparing a plurality of annular collapsible cores each having diametrical crenelations; a stacking step of concentrically stacking the plurality of collapsible cores along the rotational-shaft extension direction of the rotating electrical machine; a casting step of hot-pouring a material for the cooling element into a mold, in a state in which the plurality of collapsible cores are stacked within the mold, so that the material covers the outer peripheral surfaces and the inner peripheral surfaces of each of the plurality of collapsible cores; and a removal step, after the casting step, of removing the plurality of collapsible cores.
B22C 9/10 - CoresManufacture or installation of cores
B22C 9/24 - Moulds for peculiarly-shaped castings for hollow articles
B22D 25/02 - Special casting characterised by the nature of the product by its peculiarity of shapeSpecial casting characterised by the nature of the product of works of art
H02K 1/32 - Rotating parts of the magnetic circuit with channels or ducts for flow of cooling medium
Disclosed is a method for producing a stator for a rotary electrical machine (10), said method comprising: a step for preparing a stator core (112, 112A) that is made of a first metal material which is a magnetic body and that has, at the radially inward side thereof, a space (80) in which a rotor is to be disposed; a closing step for covering, with closing members (71, 72), at least part of the axial-direction end faces (1125, 1126) of the stator core and for closing the space; and a casting step for pouring a second metal material which is a non-magnetic body on the radially outward side of the stator core in the mold, in a state where at least part of the end surfaces of the stator core are have been covered and the space has been closed via the closing step.
H02K 15/02 - Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
Disclosed is a stator cooling structure (402) provided with a support member (60, 60A) which is a one-piece member having the shape of a cylinder along an axial direction (X) of a rotating electric machine (10), the support member (60, 60A) supporting a stator core (112) of the rotating electric machine and forming a flow path (95, 195, 35, 135) for the passage of cooling fluid. The support member includes: an inner wall portion (651) supporting an outer peripheral surface of the stator core and having a cylindrical shape; an outer wall portion (653) opposing the radially outer side of the inner wall portion and having a cylindrical shape; and one or more segmenting wall portions (359, 958, 1951, 1351) radially extending between the inner wall portion and the outer wall portion and segmenting a flow path formed between the inner wall portion and the outer wall portion.
Disclosed is a dynamo-electric machine (10) for driving a vehicle, the dynamo-electric machine (10) having a stator core (112, 112A) formed of a first metal material that is a magnetic body, and a case part (60, 60A) integrally joined to the stator core and formed of a second metal material that is a non-magnetic body. The interface where the case part and the stator core are joined forms a heat-receiving surface at which heat from the stator core is received by the case part.
An aluminum alloy having excellent high temperature strength and thermal conductivity; and an internal combustion engine piston including the alloy. The aluminum alloy includes 11.0-13.0% Si, ≤0.3% Fe, 0.3-2.0% Mg, 2.0-5.0% Cu, 3.0-4.0% Ni, 0.2-1.0% Mn, 0.05-0.4% Cr, and 0.05-0.4% V, with the remainder including aluminum and unavoidable impurities.
C22F 1/04 - Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
C22C 21/02 - Alloys based on aluminium with silicon as the next major constituent
C22F 1/043 - Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with silicon as the next major constituent
A piston in which a solid lubricant resin layer made of a resin containing a solid lubricant is formed at a skirt portion. A guide groove absent area where no guide groove is formed, which is provided in a predetermined range of the solid lubricant resin layer at a center portion in a width direction. The guide grooves directing from the both ends in the width direction of the guide groove absent area to both ends in the width direction of the skirt portion. The end portions of the guide grooves extended to end edges of the solid lubricant resin layer to form open ends. The solid lubricant resin layer and the guide grooves are formed at least at a thrust side skirt portion. The guide grooves are formed in a shape inclined upward from the guide groove absent area toward the end edges of the solid lubricant resin layer.
[Problem] To provide an aluminum alloy that exhibits an excellent high-temperature strength and an excellent thermal conductivity, and an internal combustion engine piston comprising this alloy. [Solution] The present invention provides an aluminum alloy characterized by containing Si: 11.0%-13.0%, Fe: ≤ 0.3%, Mg: 0.3%-2.0%, Cu: 2.0%-5.0%, Ni: 3.0%-4.0%, Mn: 0.2%-1.0%, Cr: 0.05%-0.4%, and V: 0.05%-0.4% with the remainder comprising aluminum and unavoidable impurities.
Provided is a piston for internal combustion engines, wherein the skirt section of the piston has reduced frictional resistance. Solid lubricant resin layers 15 consisting of a resin which contains a solid lubricant, such as molybdenum disulfide, are formed on a skirt section 12 in a predetermined pattern, and guide grooves 20 are formed in portions where the solid lubricant resin layers 15 are not formed. The portions of the solid lubricant resin layers 15, which are located in the center portions of the skirt section 12, have formed therein predetermined regions 15a where the guide grooves are not formed. The guide grooves 20 are formed so as to extend from both ends, in the width direction, of the regions 15a, where the guide grooves is not formed, toward both ends, in the width direction, of the skirt section 12. Ends of the guide grooves 20 are extended to the edge of the solid lubricant resin layers 15 to form open ends 20e. The guide grooves 20 extend from the regions 15a where the guide grooves are not formed to the edges of the solid lubricant resin layers 15 such that, in a thrust-side skirt section 12a, the guide grooves 20 are tilted upward, and in the skirt section 12b opposite the thrust side, the guide grooves 20 are tilted downward.
[Problem] The present invention provides a piston for internal combustion engines, the piston being configured so that: the piston can be efficiently cooled by reliably conducting a required amount of cooling oil to a portion requiring cooling; and the piston can be reduced in weight. [Solution] A piston 3 has a piston crown 24 having a top 21, and a pair of piston bosses respectively having piston pin holes in which piston pins are inserted, and the piston 3 is cooled by cooling oil ejected toward the rear surface 30a of the top 21 from an oil jet device having a nozzle. The top 21 has: cooling cavities 29a, 29b provided inside the top 21 at positions near at least one of the pin bosses; and inlet openings 35a, 35b provided in the rear surface 30a of the top 21 and conducting to the cooling cavities 29a, 29b oil ejected from the nozzle.
ADVANCED LASER TECHNOLOGY RESEARCH CENTER CO., LTD. (Japan)
Inventor
Narusawa, Hiroshi
Kutsuna, Muneharu
Watanabe, Tadashi
Abstract
[Problem] To provide an internal combustion engine piston having improved strength in a selected portion thereof, and a method for manufacturing the same. [Solution] The present invention solves said problem by an internal combustion engine piston 1 which at least has a portion having a dislocation density within a range of 109-1012 cm/cm3 inclusive and in which precipitates having a longer diameter of 0.2 μm or fine precipitates having a longer diameter less than 0.2 μm are produced by heating the portion having the dislocation density. The portion having the dislocation density exists within a depth range of 1 mm from the surface. The portion having the dislocation density may also be any one portion or at least two portions selected from the outer circumferential surface of the piston, the top surface thereof, the inner surface thereof, and the inner circumferential surface of a pin hole for inserting a piston pin. Also, it is preferable that the portion having the dislocation density be made of an Al-Si based alloy or an Al-Cu based alloy in which fine precipitates are produced by heating.
B23K 26/00 - Working by laser beam, e.g. welding, cutting or boring
B23K 26/122 - Working by laser beam, e.g. welding, cutting or boring in a special environment or atmosphere, e.g. in an enclosure in a liquid, e.g. underwater
B23K 26/356 - Working by laser beam, e.g. welding, cutting or boring for surface treatment by shock processing
F16J 1/01 - PistonsTrunk pistonsPlungers characterised by the use of particular materials
21.
Method for modifying surface of piston for internal combustion engine, and piston for internal combustion engine
3 or greater. The method includes: first treatment for ejecting the particle onto a surface of a piston made of aluminum-silicon alloy or aluminum-copper-based alloy in a space in which oxygen exists at arc height value of 0.07 to 0.13 mm (N), second treatment for ejecting the particle onto the surface of the piston in a space in which oxygen exists at arc height of 0.13 to 0.22 mm (N), and heating treatment applying to the piston for 1.5 hours or longer at 170 to 190° C. in a space in which oxygen exists.
F16J 1/01 - PistonsTrunk pistonsPlungers characterised by the use of particular materials
B24C 1/10 - Methods for use of abrasive blasting for producing particular effectsUse of auxiliary equipment in connection with such methods for compacting surfaces, e.g. shot-peening
22.
METHOD FOR MODIFYING SURFACE OF PISTON FOR INTERNAL COMBUSTION ENGINE, AND PISTON FOR INTERNAL COMBUSTION ENGINE
Provided is a piston for internal combustion engines which suffers no decrease in strength even in high-temperature environments. In a space in which oxygen is present, an aluminum-silicon alloy piston for internal combustion engines is subjected to a first jetting treatment in which iron-based alloy shots having a particle diameter of 20-200 µm, a thermal conductivity at 25°C of 30 W/m·k or less, and a specific gravity of 7.5 g/cm3 or higher are jetted against the surface of the piston under the conditions of an arc height value of 0.07-0.13 mm(N) and successively to a second jetting treatment in which the shots are jetted against the piston surface under the conditions of an arc height value of 0.13-0.22 mm(N). Thereafter, a heat treatment is given to the piston surface at 170-190°C for 1.5 hours or longer in the presence of oxygen to form a surface modification layer in the range from the outermost surface to a depth of about 30 µm, the layer having a structure that includes an intergranular oxide constituted of an oxide of an aluminum-iron alloy at the boundaries of crystal grains of aluminum and/or an aluminum-based alloy.
C23C 24/04 - Impact or kinetic deposition of particles
B24C 1/10 - Methods for use of abrasive blasting for producing particular effectsUse of auxiliary equipment in connection with such methods for compacting surfaces, e.g. shot-peening
B24C 11/00 - Selection of abrasive materials for abrasive blasts
The present invention relates to a piston of an internal combustion engine, including a piston body (11), a pair of skirt sections (12A, 12B), a pair of side wall sections (13A, 13B), and pin hole sections (14A, 14B), and a cavity is formed by the bottom wall surface of the piston body, inner peripheral wall surfaces of the skirt sections, and inner wall surfaces of the side wall sections. In the present invention, a bulge section (20) that extends in a direction form a region of an outer wall surface of a side wall section adjacent to the piston body and a skirt section (AR1) toward a region of the outer wall surface of the side wall section adjacent to a lateral part of a pin hole section (AR3) is provided in the outer wall surface of the side wall section.
A cooling system for a piston of an internal combustion engine includes a cooling channel (34) designed as an oil passage embedded in the piston and arranged adjacent to a top ring groove, and an oil supply portion (8) that supplies oil to the cooling channel. An amount of oil supplied from the oil supply portion to the cooling channel is made larger when an amount of heat generated in a combustion chamber is large than when the amount of heat generated in the combustion chamber is small.
An internal combustion piston comprises a modified layer produced by a surface treatment including injecting injection powders having a diameter of 20 μm to 400 μm and containing a reinforcing element to be collided with a surface of the internal combustion piston obtained by casting and forging by injecting at an injection speed of 80 m/s or more or at an injection pressure of 0.3 MPa or more, the reinforcing element improving a strength of an alloy comprising the piston when being diffused and penetrated in the alloy, wherein by the surface treatment, oxides generated on the surface of the piston by the casting and forging are removed, and surface flaws generated on the surface are repaired, whereby the modified layer is formed to have a uniformly fine-grained metal microstructure which contains the reinforcing element in the injection powders diffused and penetrated in the vicinity of the surface of the piston and an alloy element of the alloy comprising the piston.
C23C 8/00 - Solid state diffusion of only non-metal elements into metallic material surfacesChemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
A piston allowing a lubrication layer of a resin coating with a low friction coefficient to be tightly adhered to a skirt portion of a piston for an internal combustion engine, with low friction, superior wear resistance, and superior anti-seizing properties and that can reduce wear of a cylinder inner wall even if the lubrication layer is peeled off or abraded, is provided. Metal or ceramic fine particles having an average particle diameter of 20 μm to 400 μm are injected with compressed air or compressed nitrogen as a mixture fluid onto the skirt portion of the piston, made of an aluminum alloy and produced by a method such as casting or forging, at an injection speed of 80 m/s or more or an injection pressure of 0.2 MPa or more to be collided with the skirt portion, thereby uniformly making a microstructure of a piston base material fine-grained in a depth range of 1 μm to 15 μm from a surface of the skirt portion and forming a modified layer with an activated surface. A lubrication layer is formed on the modified layer, for example, by applying a resin with a low friction coefficient, while a surface of the modified layer is being activated.
A technique for using an iron plating for coating an aluminum product that results in adequate durability. An aluminum piston (lθ) used as a plated aluminum product is covered by an iron-based composite plating layer (l l). The iron-based composite plating layer (ll) contains a carbon nanomaterial, which is applied to the aluminum-based base material using a iron-based composite plating bath formed by mixing a carbon nanomaterial into an iron plating bath.
A method is provided for producing a piston for an internal-combustion engine of the structure in which a piston body which is composed of a crown having a groove for fitting a piston ring into an outer circumference surface and a skirt in connection with the bottom of the crown is provided with an annular cavity for flowing cooling liquid on an inside of the groove, the method comprising the steps of: forming the crown and the skirt individually; forming an annular groove for the annular cavity in the inner bottom of the crown and an annular rib in connection with the open edge of the annular groove before the crown and the skirt are joined together; bending the rib toward the opening of the annular groove by application of pressure to close the opening of the annular groove to thereby form the annular cavity; and joining the crown and the skirt together.
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. By locally heating and cooling performed on the piston surface by the collision with the injection powders, alloy elements are fine-grained by recrystallization, the reinforcing element in the injection powders is diffused and penetrated in the piston surface by activated adsorption, and a modified layer having a uniformly fine-grained microstructure containing the alloy elements and the reinforcing element is formed. As a result, besides improvement in strength of the piston, by the selection of the above element, such as Ti, the photocatalytic function, such as fuel modification, can also be obtained.
C23C 8/00 - Solid state diffusion of only non-metal elements into metallic material surfacesChemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
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.
patents
