JP2008095721A - Sliding member - Google Patents

Abstract

A sliding member having a high friction reducing effect is provided.
A sliding member includes a first member and a second member that slide through a viscous fluid, and at least one of a sliding surface of the first member and a sliding surface of the second member. And a fine recess 13 formed. Regarding the shape of the contact portion 14 between the first member and the second member, when the width of the contact portion is B and the length along the sliding direction 21 is H, if B / H is 1 or less, the recess is , Arranged to promote the flow of viscous fluid in the sliding direction. When B / H is larger than 1, the concave portion is arranged so as to promote the flow of the viscous fluid in the direction 22 orthogonal to the sliding direction.
[Selection] Figure 2

Description

  The present invention relates to a sliding member in which a first member and a second member slide through a viscous fluid.

  In order to reduce friction when sliding the first member and the second member through a viscous fluid such as a lubricating oil, a concave portion such as a fine depression or groove is formed on the sliding surface. (See Patent Documents 1 and 2). The formation of the concave portion is expected to have an effect of oil sump by the concave portion, control of oil flow in the contact portion by the concave portion, or an effect of micro dynamic pressure by the concave portion.

The technology for forming such fine recesses is applied, for example, to reduce the friction between the rotating and sliding crankpin and the bearing metal, and to reduce the friction between the reciprocatingly sliding piston ring and the bore. Has been.
JP 2002-213612 A JP 2002-235852 A

  Although it is possible to reduce friction by forming fine concave portions, further reduction of friction is required. Moreover, in the conventional sliding member, it is not mentioned how the fine concave portion should be arranged according to the shape of the contact portion between the first member and the second member.

  Therefore, an object of the present invention is to provide a sliding member having a high friction reducing effect.

The present invention according to claim 1, which achieves the above object, includes a first member and a second member that slide through a viscous fluid,
A fine recess formed in at least one of the sliding surface of the first member and the sliding surface of the second member,
Regarding the shape of the contact portion between the first member and the second member, when the width of the contact portion is B and the length along the sliding direction is H, B / H is 1 or less,
The concave portion is a sliding member arranged so as to promote the flow of the viscous fluid in the sliding direction.

The present invention according to claim 5, which achieves the above object, includes a first member and a second member that slide through a viscous fluid,
A fine recess formed in at least one of the sliding surface of the first member and the sliding surface of the second member,
Regarding the shape of the contact portion between the first member and the second member, when the width of the contact portion is B and the length along the sliding direction is H, B / H is greater than 1,
The concave portion is a sliding member arranged so as to promote the flow of the viscous fluid in a direction orthogonal to the sliding direction.

  According to the present invention, since the concave portion is arranged according to the shape of the contact portion between the first member and the second member, the sliding member is highly effective in reducing friction and excellent in wear resistance and seizure resistance. Can provide.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1 is a view showing a crankshaft 110 used in an internal combustion engine, FIG. 2A is a cross-sectional view showing a shaft portion and a bearing metal that rotatably holds the shaft portion, and FIG. 3A, 3B, 4A, and 4B are used to explain the shape of the contact portion 14 between the shaft portion and the bearing metal, in order to promote the flow of the lubricating oil in the sliding direction 21. The figure which shows the arrangement | positioning form of the recessed part 13, FIG. 5: is a figure where it uses for description of the form which inclined the maximum length direction of the recessed part 13 with respect to the sliding direction 21, and has arrange | positioned the recessed part 13. FIG. For easy understanding, the fine recess 13 is exaggerated.

  Referring to FIG. 1, a crankshaft 110 used for an internal combustion engine includes shaft portions such as a journal portion 111 and a pin portion 112. The journal part 111 is rotatably supported by the cylinder block via a bearing metal. The pin portion 112 is rotatably connected to the large end portion of the connecting rod through a bearing metal. As a sliding portion of an internal combustion engine, there is a sliding portion that reciprocates and slides between a cylinder bore and a piston ring, in addition to a sliding portion that rotates and slides between a shaft portion and a bearing metal.

  Referring to FIG. 2A, a sliding member 10 according to an embodiment of the present invention includes a first member 11 and a second member 12 that slide through lubricating oil as a viscous fluid, and a first member 11. And a minute recess 13 formed on at least one of the sliding surface of the second member 12 and the sliding surface of the second member 12. The first member 11 and the second member 12 rotate and slide. The first member 11 is a shaft portion such as the journal portion 111 and the pin portion 112 of the crankshaft 110, and the second member 12 is a bearing metal that rotatably holds the shaft portion. In the illustrated example, a fine recess 13 is formed on the outer peripheral surface of the first member 11.

  FIG. 2B shows a developed contact portion 14 between the first member 11 and the second member 12. Reference numeral “21” in the figure represents a sliding direction, and reference numeral “22” represents a direction orthogonal to the sliding direction 21. In the figure, the symbol “B” represents the length along the direction 22 orthogonal to the sliding direction 21, that is, the width of the contact portion 14, and the symbol “H” represents the length along the sliding direction 21. Yes. In the following description, the “direction 22 orthogonal to the sliding direction 21” is also simply referred to as “orthogonal direction 22” for simplification.

  The shape of the contact portion 14 between the first member 11 and the second member 12 is a rectangle whose length H along the sliding direction 21 is longer than the width B of the contact portion 14. Regarding the shape of the contact portion 14 between the first member 11 and the second member 12, B / H is smaller than 1. When the length H along the sliding direction 21 is large with respect to the width B of the contact portion 14, the lubricating oil interposed between the first member 11 and the second member 12 slides and the side opening is opened. The phenomenon of leaking from 15 occurs. Such a flow of lubricating oil is indicated by arrows 16 in FIGS. 3 (A), 3 (B), and 4 (A), (B). As a result, the oil film thickness decreases, the friction coefficient increases, and the friction between the first member 11 and the second member 12 increases. The speed vector of the lubricating oil is estimated to make an angle of about 20 to 45 degrees with respect to the sliding direction 21 although it varies depending on the rotational speed and the like. As described above, when the contact portion 14 has a shape in which the lubricating oil easily leaks in the orthogonal direction 22, the friction reducing effect cannot be sufficiently exhibited even if the recess portion 13 is simply formed. A similar problem can occur when the shape of the contact portion 14 is square (B / H = 1).

  Therefore, in the present invention, when B / H is 1 or less with respect to the shape of the contact portion 14 between the first member 11 and the second member 12, the flow of the lubricating oil in the sliding direction 21 is promoted through the recess 13. It is arranged like this. The arrangement of the recesses 13 facilitates the flow of the lubricating oil in the sliding direction 21 and suppresses the flow of the lubricating oil leaking from the side opening 15. As a result, it is possible to provide the sliding member 10 that can suppress the decrease in the oil film thickness and sufficiently exhibit the friction reduction effect.

  With reference to FIGS. 3A, 3B, and 4A, 4B, the recess 13 is arranged along the sliding direction 21 so as to form a region f in which the recess 13 does not exist. The concave portion 13 has a function of taking the lubricating oil therein and holding the taken lubricating oil. For this reason, from the viewpoint of flowing the lubricating oil in the sliding direction 21, the recess 13 for taking in the lubricating oil works as a resistor. Therefore, by disposing the recess 13 as described above, a region f in which the recess 13 acting as a resistor against the flow of the lubricant does not exist along the sliding direction 21 is formed. As a result, the lubricating oil in the sliding direction 21 is formed. Flow is promoted.

  3A shows a form in which the recesses 13 are arranged in a staggered pattern, and FIG. 3B shows a form in which the recesses 13 are arranged in a square grid. In the case of the staggered arrangement, the recesses 13 do not overlap each other when the recesses 13 adjacent to each other in the sliding direction 21 (for example, the recesses with 13a and the recesses with 13b) are seen in the sliding direction 21. Are arranged as follows. This is because the region f where the recess 13 does not exist is formed along the sliding direction 21. The width of the region f where the concave portion 13 does not exist along the sliding direction 21 is more easily taken in the square lattice arrangement than in the staggered lattice arrangement. Therefore, the square lattice arrangement is an arrangement that can further promote the flow of the lubricating oil in the sliding direction 21 as compared to the staggered lattice arrangement.

  With reference to FIG. 5, the concave portion 13 may be arranged with the maximum length direction of the concave portion 13 inclined with respect to the sliding direction 21. The inclination in the maximum length direction of the recess 13 with respect to the sliding direction 21 is referred to as “inclination angle α”.

  FIGS. 4A and 4B show a configuration in which the concave portion 13 is arranged with the maximum length direction of the concave portion 13 inclined with respect to the sliding direction 21. FIG. 4A shows an example in which the concave portion 13 is arranged with the same inclination direction. FIG. 4B shows the concave portion 13 with the inclination direction symmetrical about the center of the contact portion 14 in the width direction. This is an example of arrangement.

The inclination angle α of the recess 13 is not particularly limited, and is, for example, 30 degrees to 70 degrees. In order to sufficiently exert the dynamic pressure effect by the recess 13, it is desirable that the direction in which the lubricating oil is incident on the recess 13 is close to the direction perpendicular to the maximum length direction of the recess 13. By inclining the concave portion 13, the lubricating oil flowing toward the side opening 15 approaches the direction orthogonal to the maximum length direction of the concave portion 13 and enters the concave portion 13. Thereby, the lubricating oil taken into the recessed part 13 increases, the dynamic pressure effect is fully exhibited, and the more excellent friction reduction effect can be expressed. In the illustrated example in which the opening 15 is present on both sides along the width direction of the contact portion 14, the arrangement form shown in FIG. 4 (B) is compared with the arrangement form shown in FIG. 4 (A). preferable. Lubricating oil is allowed to enter the concave portion 13 in a direction perpendicular to the maximum length direction of the concave portion 13 in any of the left and right regions in the figure with the approximate center in the width direction of the contact portion 14 as a boundary. The inclination angle α of the recess 13 may be the same, or may be changed along the width direction of the contact portion 14. For example, at the substantially central portion in the width direction of the contact portion 14, the maximum length direction of the recess portion 13 is set along the orthogonal direction 22 (inclination angle α = 90) so as to match the velocity vector of the lubricating oil in the contact portion 14. In the vicinity of the end in the width direction, the maximum length direction of the recess 13 may be inclined with respect to the sliding direction 21. Lubricating oil can be made to approach the direction orthogonal to the maximum length direction of the concave portion 13 and enter the concave portion 13 over the entire width direction of the contact portion 14, and a more excellent friction reduction effect can be exhibited. It is.

  6A is a cross-sectional view showing the cylinder bore 121 and the piston ring 122 that reciprocates relative to the cylinder bore 121, and FIG. 6B shows the shape of the contact portion 14 between the cylinder bore 121 and the piston ring 122. FIGS. 7A and 7B, which are provided for explanation, are views showing the arrangement of the recesses 13 for promoting the flow of the lubricating oil in the direction 22 orthogonal to the sliding direction 21. FIG. For easy understanding, the fine recess 13 is exaggerated.

  Referring to FIG. 6A, a sliding member 30 according to an embodiment of the present invention includes a first member 31 and a second member 32 that slide through a lubricating oil as a viscous fluid, and a first member 31. And the minute recess 13 formed in at least one of the sliding surface of the second member 32. The first member 31 and the second member 32 slide back and forth. The first member 31 is a cylinder bore 121, and the second member 32 is a piston ring 122. In the illustrated example, a fine recess 13 is formed on the inner peripheral surface of the first member 31.

  FIG. 6B shows the contact portion 14 between the first member 31 and the second member 32 in an expanded state. The shape of the contact portion 14 between the first member 31 and the second member 32 is a rectangle in which the width B of the contact portion 14 is longer than the length H along the sliding direction 21. Regarding the shape of the contact portion 14 between the first member 31 and the second member 32, B / H is greater than 1. When the width B of the contact portion 14 is large with respect to the length H along the sliding direction 21, the lubricating oil interposed between the first member 31 and the second member 32 does not spread sufficiently in the orthogonal direction 22, A phenomenon of leaking from the end along the sliding direction 21 occurs. As a result, the oil film thickness decreases and the friction between the first member 31 and the second member 32 increases. As described above, when the contact portion 14 has a shape that allows the lubricating oil to easily leak in the sliding direction 21, the friction reducing effect cannot be sufficiently exhibited even if the concave portion 13 is simply formed.

  Therefore, in the present invention, when B / H is larger than 1 with respect to the shape of the contact portion 14 between the first member 31 and the second member 32, the recess 13 is lubricated in the direction 22 orthogonal to the sliding direction 21. Arranged to promote oil flow. The arrangement of the recesses 13 facilitates the flow of lubricating oil in the orthogonal direction 22, that is, the circumferential direction of the piston ring 122, and suppresses the flow of lubricating oil leaking from the end along the sliding direction 21. As a result, it is possible to provide the sliding member 30 that can suppress the decrease in the oil film thickness and can sufficiently exhibit the friction reduction effect.

  With reference to FIGS. 7A and 7B, the recess 13 has an interval w <b> 2 between the recesses 13 as viewed in a direction 22 where the interval w <b> 1 between the recesses 13 as viewed in the sliding direction 21 is orthogonal to the sliding direction 21. Arranged so as not to exceed. FIG. 7A shows a configuration in which the recesses 13 are arranged in a staggered pattern, and FIG. 7B shows a configuration in which the recesses 13 are arranged in a square grid.

  When the recesses 13 are arranged so that the interval w1 between the recesses 13 viewed in the sliding direction 21 is smaller than the interval w2 between the recesses 13 viewed in the orthogonal direction 22 as in the houndstooth arrangement, the unit length The ratio of the concave portion 13 occupying the base is larger when viewed in the sliding direction 21. As a result of the presence of more recesses 13 acting as a resistance against the flow of the lubricating oil along the sliding direction 21 than in the orthogonal direction 22, the flow of the lubricating oil in the orthogonal direction 22 is promoted.

  Even when the interval w1 between the recesses 13 viewed in the sliding direction 21 and the interval w2 between the recesses 13 viewed in the orthogonal direction 22 are equal as in the square lattice arrangement, the shape of the recess 13 is relative to the sliding direction 21. Since it is flat in the orthogonal direction 22, the ratio of the recesses 13 per unit length is greater when viewed in the sliding direction 21. Accordingly, as in the case of the staggered lattice arrangement, there are more recesses 13 acting as a resistance against the flow of the lubricating oil along the sliding direction 21 than in the orthogonal direction 22, so that the lubricating oil flows in the orthogonal direction 22. Is promoted.

  In the case of the houndstooth arrangement, the recesses 13 are overlapped when the recesses 13 adjacent to each other in the sliding direction 21 (for example, the recesses with 13a and the recesses with 13b) are seen in the sliding direction 21. You may arrange. This is because the concave portion 13 is necessarily present when viewed in the sliding direction 21, thereby making the concave portion 13 work more as a resistance against the flow of lubricating oil in the sliding direction 21.

  The square lattice arrangement is arranged in a regular square, while the rectangular lattice arrangement is arranged in a rectangle other than the square. In the case of the rectangular lattice arrangement, the recesses 13 may be arranged so that the interval w1 between the recesses 13 viewed in the sliding direction 21 is smaller than the interval w2 between the recesses 13 viewed in the orthogonal direction 22.

  In the present invention, when the first member 31 and the second member 32 are reciprocally slid, the maximum length direction of the concave portion 13 is inclined with respect to the sliding direction 21 and the concave portion 13 is excluded. is not. However, in the case of reciprocal sliding, the flow behavior of the lubricating oil interposed between the first member 31 and the second member 32 differs between forward movement and backward movement. In the case of reciprocating sliding, the flow behavior of the lubricating oil is more complicated than in the case of rotating sliding in one direction. For this reason, depending on the condition of the inclination, the effect is exhibited at the time of forward movement, but there is a possibility that a sufficient effect cannot be obtained at the time of backward movement. Therefore, in the present embodiment, a general arrangement form, that is, an arrangement form in which the maximum length direction of the recess 13 is orthogonal to the sliding direction 21 is adopted.

  There is no restriction | limiting in particular in the material of a 1st member and a 2nd member, A various material is used according to a use. For example, in a sliding member for an internal combustion engine having a piston and a cylinder, it is desirable that the sliding member be made of a metal such as iron or aluminum. Moreover, there is no restriction | limiting in particular about a shape, The sliding member of all shapes can be employ | adopted.

  As for the recessed part 13, it is desirable that the occupation area rate of the recessed part 13 in a sliding surface is 0.5% or more and 10% or less. When the occupied area ratio is smaller than 0.5%, the ratio of the concave portions 13 is too small, so that the dynamic pressure effect cannot be sufficiently exhibited, and the friction reducing effect may not be sufficiently exhibited. On the other hand, if it exceeds 10%, the ratio of the flat end portion is relatively reduced, so that the load capacity is reduced. As a result, direct contact between the metals occurs, and the friction reducing effect is not sufficiently exhibited. Friction may increase. Moreover, there is a concern that the wear resistance and the seizure resistance are also lowered. Therefore, an excellent friction reducing effect can be obtained by setting the occupied area ratio of the recess 13 to 0.5% or more and 10% or less.

  The shape of the recess 13 is preferably flat in a direction 22 orthogonal to the sliding direction 21. The shape flat in the direction 22 orthogonal to the sliding direction 21 is a shape in which the maximum length in the orthogonal direction 22 is larger than the maximum length in the sliding direction 21. The flat shape is not limited to a rectangle, and may be an elliptical shape, a polygonal shape, or a circular shape. Since the shape of the recess 13 is flat in the orthogonal direction 22, a large amount of lubricating oil can be caused to flow into the sliding portion, and friction can be reduced.

  The short side length of the recess 13 is preferably 50 μm or more and 150 μm or less, and the long side length of the recess 13 is preferably 2 times or more and 10 times or less of the short side length of the recess 13. If the length of the short side of the concave portion 13 is smaller than 50 μm, there is a risk that the inflow and retention of the lubricating oil into the concave portion 13 may not be sufficiently performed, and if it exceeds 150 μm, the load capacity decreases and the metal contact May be likely to occur. Furthermore, by making the long side length 2 times to 10 times the short side length, a large amount of lubricating oil flows into the sliding surface, and side leakage of the lubricating oil from the sliding surface is suppressed. In addition, the friction characteristics can be improved. Furthermore, the ratio between depth and size is also important. If the length of the short side of the recess 13 is smaller than 50 μm, the sensitivity to the depth increases, so that processing control becomes difficult. On the other hand, if the length of the short side of the concave portion 13 is larger than 150 μm, the concave portion 13 becomes relatively large with respect to the contact area, which is not preferable. For example, in the contact state where the shaft is bent like the crankshaft 110, there is a contact portion where the oil film is locally thin, so if the size of the recess 13 becomes too large, oil will flow into that portion, Metal contact increases and friction worsens.

  The depth of the recess 13 is desirably 0.5 μm or more and 10 μm or less. When the depth of the recess 13 is smaller than 0.5 μm, a sufficient friction reducing effect cannot be obtained particularly when the oil film is thick during high-speed sliding. On the other hand, when the thickness exceeds 10 μm, there is a problem that the load capacity is reduced and metal contact occurs in a state where the oil film is thin during low-speed sliding, resulting in deterioration of friction and seizure resistance. Therefore, an excellent friction reducing effect can be obtained by setting the depth of the recess 13 to 0.5 μm or more and 10 μm or less.

  FIG. 8A is a perspective view showing the recess 13 formed on the sliding surface, and FIG. 8B is a cross-sectional view taken along line 8B-8B in FIG. 8A.

  Referring to FIG. 8, the shape of the concave portion 13 is the length from the front side of the sliding direction 21 to the position 17 indicating the extreme value of the bottom surface of the concave portion 13 in the cross-sectional shape of the concave portion 13 in the sliding direction 21. When S is S, it is desirable that S / L is 0.2 or less. A symbol t in FIG. 8 indicates the depth of the recess 13. If S / L exceeds 0.2, the oil flow on the wall surface of the recess does not act effectively, so that the dynamic pressure effect cannot be sufficiently obtained and the friction reducing effect is not sufficiently exhibited. Therefore, when S / L is 0.2 or less, the dynamic pressure effect is sufficiently exhibited, and an excellent friction reducing effect is obtained.

  The first and second members 11, 12, 31, and 32 described above are desirably sliding members 10 and 30 that are used for sliding portions of an internal combustion engine and a transmission. By applying the first and second members 11, 12, 31, and 32 that exhibit a sufficient friction reduction, it is possible to reduce the friction in the sliding portion of the internal combustion engine or the transmission, and to improve the resistance of the sliding portion. Abrasion and seizure resistance can be improved.

(Example)
In order to confirm the effect of the present invention, various sliding members having different shapes and arrangements of the recesses were manufactured, and the following experiment was performed to obtain the friction coefficient.

  First, the effect in the movement form which carries out rotation sliding was confirmed.

  9A and 9B are cross-sectional views showing the cross-sectional shape of the recess 13 formed in the sliding surface in the embodiment. FIG. 10 is a diagram illustrating an arrangement form (X, Y, Z, V, and W) of the recesses 13 in the embodiment.

  Using an actual internal combustion engine crankshaft (see FIG. 1), the friction reduction effect was evaluated. A fine recess 13 was formed in the journal portion of the crankshaft. The crankshaft was rotated by motor drive, and the friction torque generated between the journal part and the bearing metal was measured. The diameter of the journal part is φ53 mm. Regarding the shape of the contact portion between the journal portion and the bearing metal, when the width of the contact portion is B and the length along the sliding direction 21 is H, B / H is 1 or less.

  The crankshaft is made of SV40C steel and induction hardened. The load was evaluated with no load and only the inertial force acting. The oil was 5W30 oil, the supply oil temperature was 90 ° C., and the rotation speed was 500 rpm to 6000 rpm. In Examples 1-6, the friction torque of each specification at the rotation speed of 500 rpm was obtained. In Comparative Example 1, the journal portion was not formed with a recess, and finished with an arithmetic average roughness Ra of 0.07 μm, and the friction torque at a rotation speed of 500 rpm was determined. The ratio of the friction torque of each Example to the friction torque of Comparative Example 1 was calculated, and the friction reduction effect was calculated.

  In each of Examples 1 to 6, concave fine shapes were formed in five locations of the journal portion having a diameter of 53 mm. The concave fine shape was formed by microindent processing and mask blast processing.

  As for the shape of the contact portion between the journal portion and the bearing metal, B / H is 1 or less. For this reason, the recessed part 13 was arrange | positioned so that the area | region where a recessed part does not exist along the sliding direction 21 may be formed.

  In the micro indent processing, an indenter was manufactured in order to form a desired concave portion, and the concave portion was formed by pressing the indenter against the cylindrical surface and rough plastic working.

  In the mask blasting process, a photolithography technique is used to form a concave fine shape on a resin mask, the resin mask is affixed to the surface of the journal part, and alumina abrasive grains having an average particle diameter of 20 μm are transferred from the projection nozzle to the wafer. -The distance to the center was set to 100 mm, and projection was performed under the conditions of a projection flow rate of 100 g / min and a projection pressure of 0.4 MPa to obtain a concave fine shape. After forming the concave fine shape using various methods, the bulge of the edge portion formed around the concave shape was removed with a tape wrap film having a particle size of 9 μm and used for the test.

  The cross-sectional shape of the concave portion 13 was a triangular shape (FIG. 9A) with a steep concave wall surface on the front side in the sliding direction 21 and a semicircular arc shape (FIG. 9B). In Table 1 below, the cross-sectional shape is represented by the symbols “A” and “B”.

  The arrangement of the concave portions 13 includes a staggered lattice arrangement (column Z in FIG. 10), a square lattice arrangement (column Y), and an arrangement in which the maximum length direction of the concave portion 13 is inclined with respect to the sliding direction 21 (columns X and V). , W). The inclination angle α of the recess 13 was 45 degrees (column X), 67.5 degrees (column V), and 30 degrees (column W). In Table 1 below, the arrangement is represented by the symbols “X”, “Y”, “Z”, “V”, and “W”.

  The experimental results are shown in Table 1 below.

  As shown in Table 1, the ratio of the friction torques of Examples 1 to 6 to the friction torque of Comparative Example 1 is smaller than 1 in any case. When the shape of the contact portion is B / H of 1 or less, the concave portion 13 is arranged so as to form a region where the concave portion 13 does not exist along the sliding direction 21, and the flow of the lubricating oil in the sliding direction 21 is promoted. Thus, the effect of the present invention that the friction can be reduced was confirmed. By disposing the recesses 13 by inclining the maximum length direction of the recesses 13 with respect to the sliding direction 21 (Examples 1, 4, 5, 6), a staggered lattice arrangement (Example 3) and a square lattice arrangement ( It has been found that the friction can be further reduced compared to Example 2). From Examples 1 and 4, the triangular shape (FIG. 9A) with the cross-sectional shape of the recess 13 steep in the recess wall surface on the front side in the sliding direction 21 is compared to the semicircular arc shape (FIG. 9B). Thus, it was found that the friction reducing effect is high.

  Next, the effect in the reciprocating motion form was confirmed.

  FIG. 11 is a perspective view showing the piston ring / bore simulation test machine 40, and FIG. 12 is a view showing an example of a friction coefficient waveform during reciprocating sliding obtained during the experiment.

  The piston ring / bore simulation test 40 was performed in order to confirm the effect of reducing the friction between the reciprocating members such as between the piston ring and the bore. Referring to FIG. 11, the piston ring / bore simulation tester 40 includes a ring 41 and a plate 42 that slide through lubricating oil as a viscous fluid. In the experiment, the ring 41 was fixed and only the plate 42 was slid back and forth. The double arrow in the figure indicates the sliding direction 21 and the single arrow indicates the load direction. The reciprocating sliding motion was performed by converting the rotational motion into the reciprocating motion using a crank mechanism. The sliding distance, that is, the length H along the sliding direction 21 was 30 mm per process. The width B of the contact portion between the ring 41 and the plate 42 was 40 mm. Regarding the shape of the contact portion between the ring 41 and the plate 42, B / H is larger than 1 (B / H = 40/30 = 1.3).

  The rings and plates of Examples 7 and 8 were manufactured as follows. As a material for the ring 41, an SCM435 carburizing and tempering material was used. The tip of the ring 41 was formed in an arc shape with a curvature radius of 30 mm. After finishing the surface with a radius of 30 mm to an arithmetic average roughness Ra of 0.01 μm, an amorphous hard carbon film was formed on the surface by a CVD method. On the other hand, as the material of the plate 42, a plate material of aluminum alloy for die casting (ADC12) having a thickness of 40 mm × 60 mm × 5 mm was used. A concave fine shape was formed on the plate surface by mask blasting.

  The shape of the contact portion between the ring 41 and the plate 42 is B / H larger than 1. For this reason, the recessed part 13 was arrange | positioned so that the space | interval of the recessed parts 13 seen in the sliding direction 21 may not exceed the space | interval of the recessed parts 13 seen in the orthogonal direction 22. FIG.

  In the mask blasting process, an optical lithography technique is used to form a concave fine shape on a resin mask, the resin mask is attached to the plate surface, and then alumina abrasive grains having an average particle diameter of 20 μm are transferred from the projection nozzle to the wafer. Projection was performed under the conditions of a projection flow rate of 100 g / min and a projection pressure of 0.4 MPa to obtain a fine shape of the recess. After forming the fine shape of the concave portion, the bulge of the edge portion formed around the concave shape was removed with a tape wrap film having a particle size of 9 μm and used for the test.

  In both Examples 7 and 8, the size of the recess 13 was 80 μm × 320 μm, and the occupation area ratio of the recess 13 was 2.5%. The depth of the recess 13 was 3 μm. The arrangement of the recesses 13 is a staggered lattice arrangement (see FIG. 7A) arranged in a regular triangle shape in Example 7, and a square lattice arrangement arranged in a square lattice pattern in Example 8 (see FIG. B)).

  In Comparative Example 2, an austenitic cast iron (FCA) plate finished to Ra 0.3 μm and a ring having a hard Cr plating layer finished to Ra 0.2 μm were used.

  In the experiment, the pressing load was 250 N, the sliding distance per reciprocation was 30 mm, the sliding speed was 600 times / min, and 5 W30 oil (oil supply temperature 25 ° C.) was dropped onto the sliding surface at 0.8 cc / min. I went. As shown in FIG. 10, the friction coefficient waveform obtained during the reciprocating sliding was integrated, and this value was compared to obtain a friction coefficient ratio with respect to Comparative Example 2.

  The experimental results are shown in Table 2 below.

  As shown in Table 2, the friction coefficient ratios of Examples 7 and 8 relative to Comparative Example 2 are both smaller than 1. By arranging the recesses 13 so that the interval between the recesses 13 viewed in the sliding direction 21 does not exceed the interval between the recesses 13 viewed in the orthogonal direction 22, the flow of the viscous fluid in the orthogonal direction 22 is promoted, thereby generating friction. The effect of the present invention that can be reduced was confirmed. It was found that the friction can be further reduced by arranging the concave portions 13 in a staggered lattice arrangement (Example 7) as compared to the case of arranging a square lattice pattern (Example 8).

It is a figure which shows the crankshaft used for an internal combustion engine. 2A is a cross-sectional view showing a shaft portion and a bearing metal that rotatably holds the shaft portion, and FIG. 2B is a diagram for explaining the shape of a contact portion between the shaft portion and the bearing metal. It is. FIGS. 3A and 3B are views showing the arrangement of the recesses for promoting the flow of the lubricating oil in the sliding direction. FIGS. 4A and 4B are views showing the arrangement of the recesses for promoting the flow of the lubricating oil in the sliding direction. It is a figure where it uses for description of the form which inclined the maximum length direction of the recessed part with respect to the sliding direction, and has arrange | positioned the recessed part. 6A is a cross-sectional view showing a cylinder bore and a piston ring that reciprocates with respect to the cylinder bore, and FIG. 6B is a diagram for explaining the shape of a contact portion between the cylinder bore and the piston ring. . FIGS. 7A and 7B are views showing the arrangement of the recesses for promoting the flow of the lubricating oil in the direction orthogonal to the sliding direction. FIG. 8A is a perspective view showing a recess formed on the sliding surface, and FIG. 8B is a cross-sectional view taken along line 8B-8B in FIG. 8A. 9A and 9B are cross-sectional views showing the cross-sectional shape of the recess formed on the sliding surface in the example. In an Example, it is a figure which shows the arrangement | positioning form of a recessed part. It is a perspective view which shows a piston ring / bore simulation tester. It is a figure which shows an example of the waveform of the friction coefficient at the time of reciprocating sliding obtained during experiment.

Explanation of symbols

10 sliding member,
11 first member,
12 Second member,
13 recess,
14 contact part,
15 Side opening,
17 Position indicating the extreme value of the bottom of the recess,
21 Sliding direction,
22 orthogonal direction (direction orthogonal to the sliding direction),
30 sliding member,
31 first member,
32 second member,
40 Piston ring / bore simulation tester,
41 rings,
42 plates,
110 crankshaft,
111 Journal section,
112 pin part,
121 cylinder bore,
122 piston ring,
B width of contact part,
H The length of the contact portion along the sliding direction,
f region where there is no recess along the sliding direction;
α Inclination of the maximum length of the recess with respect to the sliding direction,
w1 Spacing between recesses seen in the sliding direction,
w2 The distance between the recesses viewed in the direction perpendicular to the sliding direction.

Claims (13)

A first member and a second member sliding through a viscous fluid;
A fine recess formed in at least one of the sliding surface of the first member and the sliding surface of the second member,
Regarding the shape of the contact portion between the first member and the second member, when the width of the contact portion is B and the length along the sliding direction is H, B / H is 1 or less,
The said recessed part is a sliding member arrange | positioned so that the flow of the said viscous fluid to the said sliding direction may be accelerated | stimulated.   The sliding member according to claim 1, wherein the concave portion is arranged so as to form a region where the concave portion does not exist along the sliding direction.   The sliding member according to claim 1, wherein the concave portion is disposed with a maximum length direction of the concave portion inclined with respect to the sliding direction.   The sliding member according to any one of claims 1 to 3, wherein the first member and the second member rotate and slide. A first member and a second member sliding through a viscous fluid;
A fine recess formed in at least one of the sliding surface of the first member and the sliding surface of the second member,
Regarding the shape of the contact portion between the first member and the second member, when the width of the contact portion is B and the length along the sliding direction is H, B / H is greater than 1,
The said recessed part is a sliding member arrange | positioned so that the flow of the said viscous fluid to the direction orthogonal to the said sliding direction may be accelerated | stimulated.   The said recessed part is arrange | positioned so that the space | interval of the recessed parts seen in the said sliding direction may not exceed the space | interval of the recessed parts seen in the direction orthogonal to the said sliding direction. The sliding member as described.   The sliding member according to claim 5 or 6, wherein the first member and the second member slide back and forth.   The sliding member according to any one of claims 1 to 7, wherein the concave portion has an area ratio of the concave portion on the sliding surface of 0.5% or more and 10% or less.   The sliding member according to claim 1, wherein the shape of the recess is flat in a direction orthogonal to the sliding direction.   10. The sliding according to claim 9, wherein a short side length of the concave portion is not less than 50 μm and not more than 150 μm, and a long side length of the concave portion is not less than 2 times and not more than 10 times a short side length of the concave portion. Element.   The sliding member according to claim 1, wherein the recess has a depth of 0.5 μm or more and 10 μm or less.   In the cross-sectional shape of the concave portion in the sliding direction, when the length of the outermost surface is L and the length from the front side of the sliding direction to the position showing the extreme value of the bottom surface of the concave portion is S, S / L is 0.2 or less. The sliding member according to claim 1, wherein the sliding member is provided.   The sliding member according to any one of claims 1 to 12, wherein the first member and the second member are used for a sliding portion of an internal combustion engine.

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