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US 6,739,238 B2Granted
Sliding structure for a reciprocating internal combustion engine and a reciprocating internal combustion engine using the sliding structure
AssigneeNissan Motor Co., Ltd.
InventorsKenshi Ushijima, Yoshiteru Yasuda, Makoto Kano
Life of this patent
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Abstract
A sliding structure for a reciprocating internal combustion engine, including sliding elements relatively slidable via lubricating oil therebetween, the sliding elements including sliding surfaces opposed to each other and lubricated with a laminar flow of the lubricating oil. The sliding surfaces each have base surfaces and microscopic dimples or grooves which are so constructed as to prevent reduction of flow resistance to the lubricating oil passing through a clearance between the sliding surfaces and assure a lubricating oil film thickness required for reducing friction loss between the sliding elements.
Claims31
A sliding structure for a reciprocating internal combustion engine, comprising:
- sliding elements relatively slidable via lubricating oil therebetween, the sliding elements including sliding surfaces opposed to each other and lubricated with a laminar flow of the lubricating oil, the sliding surfaces defining a first clearance therebetween from which the laminar flow of the lubricating oil leaks, wherein, assuming that the sliding surfaces are completely smooth surfaces defining a second clearance therebetween from which the laminar flow of the lubricating oil leaks, a first surface integral T of an inverse number of the first clearance is smaller than a second surface integral Tsmooth of an inverse number of the second clearance under condition that flow resistances to the laminar flows of the lubricating oil which leak from the first and second clearances are equal to each other with respect to pressure gradient in a direction of leakage of the laminar flows of the lubricating oil and wherein each of the sliding surfaces comprises a base surface with microscopic irregularities having a maximum height, and a plurality of dimples separated from each other by the base surface, the dimples having an average value of maximum depths which is larger than the maximum height, an average value of maximum diameters of the dimples of one of the sliding surfaces being smaller than an average value of minimum distances between the dimples of the other of the sliding surfaces.
A sliding structure for a reciprocating internal combustion engine, comprising:
- sliding elements relatively slidable via lubricating oil therebetween, the sliding elements including sliding surfaces opposed to each other and lubricated with a laminar flow of the lubricating oil, each of the sliding surfaces including a base surface with microscopic irregularities having a maximum height t, and a plurality of dimples formed in a separate relation to each other on the base surface, wherein, if the sliding surfaces are completely smooth surfaces defining a minimum clearance therebetween an amount of the lubricating oil introduced into the minimum clearance upon relative motion of the sliding elements balances with an amount of the lubricating oil discharged therefrom by pressure generated between the sliding elements, the minimum clearance is larger than a sum of the maximum heights of the microscopic irregularities of the base surfaces and smaller than an average value of maximum depths of the dimples of at least one of the sliding surfaces, and an average value of maximum diameters of the dimples of one of the sliding surfaces is smaller than an average value of minimum distances between the dimples of the other of the sliding surfaces.
A sliding structure for a reciprocating internal combustion engine, comprising:
- a cylinder wall including a first sliding surface;
- a piston skirt reciprocally moveable relative to the cylinder wall, the piston skirt including a second sliding surface opposed to the first sliding surface;
- and a piston ring mounted to the piston skirt, the piston ring including a third sliding surface opposed to the first sliding surface;
- each of the first, second and third sliding surfaces including a base surface with microscopic irregularities having a maximum height t, and a plurality of dimples separated from each other by the base surface, wherein an average value d of maximum diameters of the dimples of the first and third sliding surfaces is not more than an axial length of the piston ring, wherein a relationship between the average value d of maximum diameters of the dimples of the first sliding surface, an average value LS of minimum distances between the dimples of the second sliding surface, and an average value LR of minimum distances between the dimples of the third sliding surface is expressed as follows:
- d<LS and d<LR, and wherein the maximum height t of the microscopic irregularities of the base surface is smaller than a smaller one of minimum clearances generated between the first and second sliding surfaces and between the first and third sliding surfaces, the minimum clearances being determined assuming that the first, second and third sliding surfaces are completely smooth surfaces, and that an amount of the lubricating oil introduced into the minimum clearances upon relative motion of the cylinder wall, the piston skirt and the piston ring balances with an amount of the lubricating oil discharged from the minimum clearances by pressure generated between the cylinder wall, the piston skirt and the piston ring under a maximum operating time condition of the reciprocating internal combustion engine.
2 more elements
A sliding structure for a reciprocating internal combustion engine for automobiles, comprising:
- a cylinder wall including a first sliding surface, the first sliding surface including a base surface with microscopic irregularities having a maximum height of not more than 1 μm, and a plurality of dimples separated from each other by the base surface, the dimples having a depth ranging from 1 μm to 50 μm and an average value of maximum diameters thereof which is not more than 50 μm;
- a piston skirt reciprocally moveable relative to the cylinder wall, the piston skirt including a second sliding surface opposed to the first sliding surface, the second sliding surface including a base surface with microscopic irregularities having a maximum height of not more than 5 μm, and a plurality of dimples separated from each other by the base surface, the dimples having a depth ranging from 1 μm to 50 μm, an average value of maximum diameters thereof which is not more than 1 mm, and an average value of minimum distances therebetween which is larger than the average value of maximum diameters of the dimples of the first sliding surface of the cylinder wall;
- and a piston ring mounted to the piston skirt, the piston ring including a third sliding surface opposed to the first sliding surface, the third sliding surface including a base surface with microscopic irregularities having a maximum height of not more than 1 μm, and a plurality of dimples separated from each other by the base surface, the dimples having a depth ranging from 1 μm to 50 μm, the average value of maximum diameters thereof which is not more than 50 μm, and an average value of minimum distances therebetween which is larger than the average value of maximum diameters of the dimples of the first sliding surface of the cylinder wall.
A sliding structure for a reciprocating internal combustion engine, comprising:
- sliding elements relatively slidable via lubricating oil therebetween, the sliding elements including sliding surfaces opposed to each other and lubricated with a laminar flow of the lubricating oil, the sliding surfaces including base surfaces with microscopic irregularities having maximum heights t, respectively, and a plurality of grooves extending at an angle of not less than 45 degrees relative to a direction of the sliding motion of the sliding elements without intersecting, the grooves having an average value of maximum depths which is larger than the maximum heights t, the grooves having maximum widths of not more than a contact length CL in the direction of the sliding motion over which the sliding surfaces are in contact with each other via a film of the lubricating oil disposed therebetween, wherein an average value b of the maximum widths of the grooves of one of the sliding surfaces is smaller than an average value of minimum distances between the grooves of the other of the sliding surfaces.
A reciprocating internal combustion engine, comprising:
- a sliding structure including sliding elements relatively slidable via lubricating oil therebetween, the sliding elements including sliding surfaces opposed to each other and lubricated with a laminar flow of the lubricating oil, the sliding surfaces defining a first clearance therebetween from which the laminar flow of the lubricating oil leaks, wherein, assuming that the sliding surfaces are completely smooth surfaces defining a second clearance therebetween from which the laminar flow of the lubricating oil leaks, a first surface integral T of an inverse number of the first clearance is smaller than a second surface integral Tsmooth of an inverse number of the second clearance under condition that flow resistances to the laminar flows of the lubricating oil which leak from the first and second clearances are equal to each other with respect to pressure gradient in a direction of leakage of the laminar flows of the lubricating oil and wherein each of the sliding surfaces comprises a base surface with microscopic irregularities having a maximum height, and a plurality of dimples separated from each other by the base surface, the dimples having an average value of maximum depths which is larger than the maximum height, an average value of maximum diameters of the dimples of one of the sliding surfaces being smaller than an average value of minimum distances between the dimples of the other of the sliding surfaces.
Dependencies are inferred from the claim text.