JP2002213612A - Sliding part for internal combustion engine and internal combustion engine using the sliding part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding part for a reciprocating internal combustion engine, preventing reduction of flow resistance of lubricating oil flowing between sliding surfaces to ensure oil film thickness of the lubricating oil, which can reduce frictional loss so that efficiency of the internal combustion engine can be improved. SOLUTION: A dimple-shaped hollow 11 is formed in a base surface 10 of both sliding surfaces having irregularities of maximum height t, when the closest distance approached between the sliding surfaces is defined as h, when inflow/ outflow amounts of lubricating oil relating to a clearance between two parts are balanced when both the sliding surfaces are made a completely smoothed surface, h is set larger than t, at least one of averaged depths of the hollow in each sliding surface is set larger than h, a maximum diameter of the hollow in both the sliding surfaces is set to the shortest span or less in a range formed with a lubricating oil film, and an averaged value d of the maximum width of a groove in one sliding surface is set smaller than an averaged value L of the minimum distance between grooves in the other sliding surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for reducing friction based on a fine shape formed on a sliding surface of a machine component.
For example, the present invention relates to a surface roughness structure of a sliding component for a reciprocating internal combustion engine capable of reducing a friction loss of a reciprocating internal combustion engine for an automobile.

[0002]

2. Description of the Related Art As sliding parts for reciprocating internal combustion engines,
For example, as a surface shape of a bearing metal supporting a crankshaft, a bearing metal having a lubricating oil pocket having a predetermined depth and area on a sliding surface is disclosed in Japanese Patent Application Laid-Open No. 2000-504089.
The sliding surface of a crankshaft, which is a mating part of such a bearing metal, is disclosed in, for example, FIG.
As shown in the figure, the deep valley portion on the fine uneven surface is
It is characterized by being continuous over a certain wide area, and the above-mentioned floating pockets exist on the surface of the bearing metal, and due to the effect of the oil pool, seizure resistance during insufficient lubrication or high rotation and high load is reduced. Has improved.

Further, for example, as shown in FIG. 12, the sliding surface of the piston skirt is processed by a method such as turning or roller rolling so that the ten-point average roughness Rz becomes 20 μm or more. Even if the wear of the part progresses, a part is left as an oil sump, and due to the effect of the oil sump, the seizure resistance at the time of insufficient lubrication and high rotation and high load is also reduced. Has improved. The sliding surface of the cylinder bore, which is the mating part, is processed in a cross hatch shape, for example, as shown in FIGS. It is continuous.

[0004]

However, in the above-described surface roughness structure of the sliding component, the thickness of the lubricating oil film formed between the sliding surfaces receiving the load is caused by the relative motion. Then, it is determined by the balance between the flow rate of the lubricating oil caught in the gap between the parts and the flow rate of the lubricating oil leaking from the gap due to the pressure caused by the load. At this time, the oil that is about to leak from the gap flows through the space formed by the surface shapes of the two surfaces to be rebuilt, and flows more from the portion where the flow resistance is small. Since the flow is laminar, the flow rate is proportional to the cube of the gap. Therefore, if there is a space with a large gap continuously in the flow direction, the flow resistance will be greatly reduced.

[0005] In the case of sliding in the above-described combination, a portion where a deep valley portion in a sliding surface of a crankshaft or a cylinder bore is continuous over a wide range is formed on a bearing metal or a piston skirt. There is a high probability of connecting the pits of the pool, and the oil that tries to leak from the gap selectively flows through this continuous large area, reducing the flow resistance and thereby reducing the oil film thickness. However, there is a problem that the shear force of the fluid increases and friction loss increases, and solving such a problem is a problem in reducing the friction between the sliding surfaces and improving the efficiency of the internal combustion engine. I was

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in a conventional sliding component for a reciprocating internal combustion engine, and has been made to reduce the flow resistance of lubricating oil flowing between sliding surfaces of two components. It is an object of the present invention to provide a sliding component for a reciprocating internal combustion engine capable of preventing the occurrence of friction, reducing the friction loss by securing the oil film thickness of the lubricating oil, and thereby improving the efficiency of the internal combustion engine. .

[0007]

A sliding part for an internal combustion engine according to the first aspect of the present invention is a two-part part which relatively moves in an internal combustion engine and is lubricated with lubricating oil in a laminar state between sliding surfaces. The surface roughness structure of the sliding surfaces of the two sliding surfaces, wherein the flow resistance to the pressure gradient in the flow direction of the lubricating oil leaking from the gaps in the gap shape between the two parts formed by the surface shapes of the two sliding surfaces. In a state where the flow resistance is equal to the flow resistance in the gap formed between the two parts when is completely smooth, a value obtained by dividing the area of the reciprocal of the gap between the two parts is used in the gap formed by the completely smooth surface. The sliding component according to claim 2 as an embodiment of the sliding component, wherein both sliding surfaces have a base surface having irregularities of a maximum height t. Din surrounded by the base surface H / t is greater than 1 and the maximum diameter of the dents on both sliding surfaces is the shortest of the sliding surfaces, where H is the maximum depth of the dent on each sliding surface. Where d <L when the average value of the maximum diameter of the depression on one sliding surface is d and the average value of the minimum distance between the depressions on the other sliding surface is L, The sliding component according to claim 3 of the present invention has a surface roughness structure on the sliding surface of the two components which are also relatively moved in the internal combustion engine and are lubricated with lubricating oil in a laminar flow state between the sliding surfaces. hand,
A base surface having irregularities of the maximum height t on both sliding surfaces has a dimple-shaped depression surrounded all around the base surface. When the inflow of the lubricating oil due to the relative movement into the gap formed in the gap and the outflow of the lubricating oil due to the pressure generated between the two parts are balanced, the closest approach distance between the sliding surfaces is defined as h. Where h is greater than t, at least one of the average depths of the depressions on each sliding surface is greater than h, and the maximum diameter of the depressions on both sliding surfaces is the shortest span in the range in which the lubricating oil film is formed. When d is the average value of the maximum diameter of the depression on one sliding surface and L is the average value of the minimum distance between the depressions on the other sliding surface, d <L. It is characterized by the fact that such a configuration in a sliding part for an internal combustion engine solves the conventional problem described above. It is the order of means.

[0008] As an embodiment of the sliding component according to claim 3 of the present invention, in the sliding component according to claim 4,
The average value of the maximum diameter of the dents on the sliding surface with the higher surface hardness of both sliding surfaces was d, and the average value of the minimum distance between the dents on the sliding surface with the lower surface hardness was L. Sometimes, d <L, and as an embodiment,
In the sliding component according to claim 5, when the average value of the maximum diameter of the depression in the sliding surface having the lower surface hardness of both sliding surfaces is D, D> d, In the sliding component according to the sixth aspect, the maximum height of the irregularities on the base surface of the sliding surface having the higher surface hardness of the two sliding surfaces is smaller than h and the sliding surface having the lower surface hardness is used. The maximum height of the unevenness of the base surface on the surface is larger than h, and in the sliding component according to claim 7, the h is the operating condition assumed in a reciprocating internal combustion engine equipped with the sliding component. Claim 8 wherein the calculation is made under the condition having the largest effect on friction loss.
In the sliding components according to the above, when h is calculated as h0, which is calculated under the condition having the largest effect on the friction loss among the operating conditions assumed in the reciprocating internal combustion engine equipped with the sliding component, H under other operating conditions
May be smaller than h0. In the sliding component according to the ninth aspect, the condition that has the largest effect on the friction loss in the seventh and eighth aspects is set to one-third of the maximum rotation speed. In the sliding component according to the tenth aspect, the operating condition when the operating time is the longest is set to one-third of the maximum rotation speed and one-fourth of the maximum load. It is characterized by the condition.

In the sliding component according to the eleventh aspect, the component having the higher surface hardness of the sliding surface is a crankshaft, and the component having the lower surface hardness is a bearing metal for supporting the crankshaft. In this case, assuming that both parts are those of an internal combustion engine for an automobile, the maximum height of the unevenness of the base surface on the sliding surface of the crankshaft is one.
μm or less, the average depth of the depression is 1 to 50 μm, the average depth of the depression on the bearing metal sliding surface is 1 to 50 μm, and the average value of the maximum diameter thereof is 1 mm or less. The sliding component according to claim 13 is characterized in that the component having the higher surface hardness of the sliding surface is a cylinder bore, and the component having the lower surface hardness is a piston skirt. At this time, assuming that both parts are those of an automotive internal combustion engine, the maximum height of the unevenness of the base surface on the cylinder bore sliding surface is 1 μm.
m, the average depth of the depressions is 1 to 50 μm, the average depth of the depressions on the piston skirt sliding surface is 1 to 50 μm, and the average value of the maximum diameter thereof is 1 mm or less. In the moving part, the component having the higher surface hardness of the sliding surface is a piston ring, and the component having the lower surface hardness is a cylinder bore. As described, both parts are for an internal combustion engine for automobiles, and the maximum height of the irregularities on the base surface on the piston ring sliding surface is 1 μm.
Hereinafter, the average depth of the depression can be 1 to 50 μm, the average depth of the depression on the sliding surface of the cylinder bore can be 1 to 50 μm, and the average of the maximum diameter can be 1 mm or less. Further, in the sliding component according to claim 17, the component having a higher surface hardness of the sliding surface is a cylinder bore, and the component having a lower surface hardness is a piston ring. At this time, assuming that both parts are of an internal combustion engine for an automobile, the maximum height of the unevenness of the base surface on the cylinder bore sliding surface is 1 μm.
m, the average depth of the depression is 1 to 50 μm, the average depth of the depression on the piston ring sliding surface is 1 to 50 μm, and the average value of the maximum diameter thereof is 1 mm or less.

A sliding part for an internal combustion engine according to a nineteenth aspect of the present invention relates to a surface roughness structure at a portion where a piston skirt and a piston ring of the internal combustion engine slide with a cylinder bore. Under the condition that the operating time assumed in the engine is longest, lubricating oil due to relative movement to the gap formed between the parts when the sliding surface between the piston skirt and the piston ring and the cylinder bore is assumed to be a perfectly smooth surface The distance between the sliding surfaces when the inflow amount of the lubrication oil and the outflow amount of the lubricating oil due to the pressure generated between the parts are balanced is h, and the piston skirt, the cylinder bore, and the piston ring at the center of the piston vertical movement stroke Let h be the smaller value of h in the two sets of sliding surfaces of the cylinder bore and the cylinder bore. The sliding surface of the piston ring is h and
On a base surface having irregularities with a maximum height smaller than that, the base surface has a dimple-shaped depression entirely surrounded by the base surface, the depth of the depression is larger than h, and the average value of the maximum diameter of the depression Is the width of the sliding surface of the piston ring, and the sliding surface of the piston skirt has a dimple-shaped depression entirely surrounded by the base surface having irregularities of the maximum height smaller than h. The depth of the depression is larger than h, the average value of the maximum diameter of the depression of the cylinder bore is d, the average value of the minimum distance between the depressions of the piston skirt is L1, and the minimum value of the distance between the depressions of the piston ring is L1. When the average value of the distance is L2, d <L1 and d <L2. The sliding component for an internal combustion engine according to claim 20 of the present invention is a cylinder component, a piston skirt and a piston ring of an internal combustion engine. The present invention relates to a surface roughness structure on a sliding surface, wherein a sliding surface of a cylinder bore is entirely surrounded by a base surface having irregularities of 1 μm or less in maximum height, and has a depth of 1 to 1 μm. 50 μm, the average diameter d of the maximum diameter is 50 μm or less, and the sliding surface of the piston skirt that slides on the cylinder bore has a maximum height of 5 μm.
m of the piston ring, which is entirely surrounded by the base surface, has a depth of 1 to 50 μm, has an average maximum diameter of 1 mm or less, and slides on the cylinder bore. The sliding surface has a recess having a maximum height of 1 μm or less on a base surface having irregularities, all of which are surrounded by the base surface, a depth of 1 to 50 μm, and an average maximum diameter of 50 μm or less. When the average value of the minimum distance between the depressions of the piston skirt is L1 and the average value of the minimum distance between the depressions of the piston ring is L2, d <L1 and d <L2.
Is characterized in that:

A sliding part for an internal combustion engine according to a twenty-first aspect of the present invention is a two-part sliding surface lubricated with a lubricating oil having a relative flow in the internal combustion engine and having a laminar flow between the sliding surfaces. In relation to the surface roughness structure of the above, the two sliding surfaces intersect with each other a plurality of grooves that form an angle of 45 ° or more with the sliding direction on a base surface having irregularities of maximum heights t1 and t2 (μm). And the maximum depth of the groove on both sliding surfaces is H (μ
m), H / t1 and H / t2 are greater than 1 and the maximum width of the groove is less than or equal to the contact length in the sliding direction where the lubricating oil film is formed, and the maximum width of the groove on one of the sliding surfaces B <μL, and the average value of the minimum distance between the grooves on the other sliding surface is L (μm), where b <L. As an embodiment of the surface roughness structure of the present invention, in the sliding component according to claim 22, lubricating oil is formed by relative movement to a gap formed between the two components when both sliding surfaces are completely smooth. When the closest approach distance between the sliding surfaces is defined as h when the inflow amount and the outflow amount of the lubricating oil due to the pressure generated between the two parts are defined as h, the configuration is such that t1 and t2 are smaller than h. As an embodiment, in the sliding component according to claim 23, both sliding surfaces When the average value of the maximum width of the groove on the sliding surface with the higher surface hardness is b and the average value of the minimum distance between the grooves on the sliding surface with the lower surface hardness is L, b < L, and in the sliding component according to claim 24, when the average value of the maximum width of the groove on the sliding surface having the lower surface hardness of both sliding surfaces is B, B> b, and in the sliding component according to claim 25, in the condition that h has the largest effect on friction loss among operating conditions assumed in a reciprocating internal combustion engine equipped with the sliding component. The sliding component according to claim 26, wherein the component having the higher surface hardness of the sliding surface is the cylinder bore, and the component having the lower surface hardness is the piston skirt. And In the sliding component according to the twenty-seventh aspect, the two components are those of an internal combustion engine for an automobile, and the unevenness of the base surface on the sliding surface of the cylinder bore and the piston skirt is set to 1 μm or less in maximum roughness indication Ry. The average depth of the groove in the bore is 1 to 50
μm, the average of the minimum distance between the grooves is 100 μm or less, and the average depth of the grooves in the piston skirt is 5 to 5.
The average value of the minimum distance between the grooves can be set to 1 mm or less.

As a further embodiment, in the sliding component according to claim 28, a gap formed between the piston skirt and the component when the sliding surface between the piston ring and the cylinder bore is assumed to be a completely smooth surface. When the inflow of lubricating oil due to relative motion to the lubricating oil and the outflow of lubricating oil due to the pressure generated between the parts are balanced, the closest distance between the sliding surfaces is h, H at two sliding surfaces of a piston skirt and a cylinder bore and a piston ring and a cylinder bore
H0, the average value of the maximum width of the groove in the cylinder bore is b, the average value of the minimum distance between the grooves is L ', and the average value of the minimum distance between the grooves in the cylinder bore is L. When the contact width between the piston ring and the cylinder bore in the sliding direction is a, the maximum height of the irregularities on the base surface of the piston skirt, the piston ring and the cylinder bore is h0 or less, and b> L, b + L ′ <a
In the sliding component according to claim 29, the base surfaces of the sliding surfaces of the piston skirt, the piston ring, and the cylinder bore are each 1 μm.
m, the average value b of the maximum width of the groove in the cylinder bore is 1 to 50 μm, the average depth of the groove is 1 to 10 μm, and the average value L ′ of the minimum distance between the grooves is 100.
μm or less, the average value B of the maximum width of the groove in the piston skirt is 50 μm or more, the average depth of the groove is 5 to 50 μm,
The average value L of the minimum distance between the grooves is 50 μm or more and 1 mm or less, and such a configuration in the surface roughness structure of the sliding part for the internal combustion engine is used as a means for solving the above-mentioned conventional problems. It is characterized by.

The internal combustion engine according to the present invention has a surface roughness structure on the sliding surfaces of two parts which are relatively moved in the internal combustion engine and are lubricated with lubricating oil in a laminar state between the sliding surfaces. The flow resistance to the pressure gradient in the flow direction of the lubricating oil leaking from the gap in the gap shape between the two parts formed by the surface shape of the moving surface is 2 when both sliding surfaces are completely smooth.
When the flow resistance is equal to the flow resistance in the gap formed between the parts, use a sliding part in which the value obtained by dividing the reciprocal of the gap between the two parts by area is smaller than the value in the gap formed by the completely smooth surface. It is characterized by having a configuration that has been adopted.

[0014]

According to the sliding component for an internal combustion engine according to the present invention, a dimple-shaped dent or a sliding direction is formed on the base surface having the above-mentioned structure, in particular, the base surface having the unevenness of the maximum height t. Equipped with a groove at an angle of 45 ° or more, when both sliding surfaces are completely smooth, the closest distance between the sliding surfaces when the inflow and outflow of lubricating oil to the gap between the two parts is balanced. H
If the maximum depth of the depression on each sliding surface is larger than t, the maximum diameter of the depression on both sliding surfaces is less than the shortest span of the sliding surface, The average value of the maximum diameter of the dent of the other is smaller than the average value of the minimum distance between the dents on the other sliding surface, or h is larger than t,
One or both of the average depths of the depressions on each sliding surface may be greater than h, the maximum diameter of the depressions on both sliding surfaces may be less than the shortest span in the range in which the lubricating oil film is formed, The maximum depth of the groove on the moving surface is larger than t, the maximum width of the groove on both sliding surfaces is less than the contact length in the sliding direction in which the lubricating oil film is formed, or one of the sliding surfaces By making the average value of the maximum width of the groove smaller than the average value of the minimum distance between the grooves on the other sliding surface,
The probability that the dents or grooves functioning as oil reservoirs formed on one sliding surface are connected via the dents or grooves on the other sliding surface is extremely low, and a decrease in flow resistance is avoided. It can ensure the thickness of the lubricating oil film and reduce the friction loss between sliding parts for internal combustion engines, such as bearing metal and crankshaft, piston skirt and cylinder bore, piston ring and cylinder bore, etc. An extremely excellent effect that the output efficiency of the device can be increased.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described based on embodiments.

(Embodiment 1) First, an example in which the surface roughness structure of a sliding part according to the present invention is applied to a sliding surface of a bearing metal and a crankshaft of an internal combustion engine for an automobile will be described. The internal combustion engine here has a displacement of 2000c.
c and a maximum rotation number of about 6000 rpm.

FIG. 1 shows the shapes of the bearing metal and the crankshaft. FIG. 1 (a) is a cross-sectional view of the bearing metal and the crankshaft, and FIG. 1 (b) houses the bearing metal. Perspective view of bearing box, FIG. 1
FIG. 2C is a horizontal cross-sectional view taken along line CC of FIG. The bearing metal 31 is a pair of half-cylindrical cylinders and supports the crankshaft 32 from above and below. The axial length S1 shown in FIG.
It is shorter than the circumferential length S2, and is the shortest span of the sliding surface in this embodiment.

Since a sufficient amount of lubricating oil is supplied between the bearing metal 31 and the sliding surface of the crankshaft 32 and relative rotation is constantly generated, a fluid lubricating oil film f is formed. In this case, a normal operating condition that is frequently used, that is, a condition in which the frequency of operation is high in this embodiment and the rate at which the friction loss affects the fuel consumption is large is 2000 rpm.
Under the operating conditions of m and 1/4 load, the oil film thickness becomes 2 μm.

The crankshaft 32 is made of steel, and is adjusted to a hardness of about Hv500 by heat treatment or the like. When the material is polished using a wrapping tape, a very fine and cross-shaped polishing groove is formed. Average roughness Ra: 0.08 μm, maximum height (t)
An extremely smooth base surface 10 of Ry: 0.5 μm was formed.

Next, YA is applied to the smooth base surface 10.
By irradiating a pulsed laser beam using a G laser device, independent fine dimple-shaped depressions 11 as shown in FIG. 2 were formed. In this embodiment, the depression 11 has a substantially spherical shape.
The depth k ₁ to _N of ₁ is 3 to 5 μm, and the average value is 4 μm (k = 4
μm), the diameter d _{1 to N of the} depression 11 was 10 to 30 μm, the average value was 20 μm (d = 20 μm), and the area ratio of the depression 11 was 30 to 80%.

On the other hand, the bearing metal 31 has a maximum height t (R
y) A base surface 10 having irregularities of 1.0 μm was formed, and a similar depression 11 was formed by irradiating the base surface 10 with a pulsed laser beam. The depth k ₁ to _N of the depression 11 is 3 to 10 μm, and the average value is 7 μm (k
= 7 μm), and the diameter d _{1 to N of the} depression 11 is 50 to 80 μm
And the average value is 60 μm (d = 60 μm).
Pitches P _{1 to N} are 110 to 180 μm, average 150 μm
(The average value of the minimum distance L between the depressions L = 30 μm).

In a crankshaft and a bearing metal having such a surface roughness, the thickness of the lubricating oil film formed between the sliding surfaces receiving the load is determined by the flow rate of the lubricating oil in the clearance caused by the rotation of the crank. Is determined by the balance with the flow rate leaking from the gap due to the pressure caused by the load. In this embodiment, under the above operating conditions in which the rate at which the friction loss affects the fuel consumption is large, when the oil film thickness h is 2 μm, the balance is obtained when considering the perfectly smooth surface. At this time, the oil that is about to leak from the gap flows through the space formed by the surface shapes of the two sliding surfaces, and flows more from the portion where the flow resistance is small. Since the flow is laminar, the flow rate of the lubricating oil is proportional to the cube of the gap. Therefore, if there is a continuous space with a large gap in the flow direction, the flow resistance is greatly reduced. In this embodiment, while the average value d of the maximum diameter of the depression 11 on the crankshaft sliding surface is 20 μm,
Since the average value L of the minimum distance between the depressions 11 on the bearing metal sliding surface is 30 μm (d <L), the probability that the depressions are connected to each other is extremely small. There is almost no possibility of continuity in the direction, and the oil that tries to leak out of the gap is between the base surface 10 around the depression 11 of the crankshaft and the base surface 10 around the depression 11 of the bearing metal. Must pass through a relatively narrow flow path, and the flow resistance of the oil that tends to leak from the gap increases. As a result, even when the overall unevenness is large, the closest approach distance between the sliding surfaces does not decrease, and the fluid shear force at the concave portion decreases without increasing the fluid shear force at the tip of the roughness. Friction loss can be reduced.

Next, such effects will be examined quantitatively.

When the condition of d <L is satisfied as in this embodiment, the flow of the lubricating oil always passes through a narrow portion of the gap distribution. Considering a two-dimensional shape, it can be approximated by resistance to laminar pressure flow perpendicular to the irregularities. This flow resistance is calculated with respect to the roughness shape, and the oil film thickness h = 2 μ is considered as a completely smooth surface.
The approaching state between the two surfaces, which is the same as the flow resistance at m, was determined. If the roughness shape of the base surface between the depressions is considered to be three-dimensionally random, the flow resistance can be approximated in a smooth case, so that the flow resistance is made smooth. The state of proximity between the two surfaces corresponds to the sliding state of the two surfaces under the operating conditions.

The friction loss due to shear sliding at that time can be approximated as being proportional to the area of the reciprocal of the oil film thickness.
Here, the influence of the roughness shape of the base surface between the depressions on the reciprocal of the oil film thickness is large and cannot be ignored. Therefore, the sum of the reciprocals of the oil film thickness was calculated for a shape obtained by combining the random roughness shape of the base surface between the depressions and the dimple shape of the depressions. FIG. 4 shows an example of the cumulative distribution of the height of the combined roughness (Abbott's load curve) when the roughness shape is changed, and shows the parameters obtained by organizing the calculated data.

The value corresponding to the height of the roughness of the base surface between the depressions is denoted by r, the value corresponding to the depth of the depressions is denoted by H, and the value corresponding to the area ratio of the depressions is denoted by C. Arranged by these parameters, the reciprocal area value T of the oil film thickness corresponding to the friction loss and the value of T on a perfectly smooth surface having the same flow resistance as Tsmooth are shown in FIGS. Show.

FIG. 5 shows a value H / h corresponding to the depth of the depression.
Here, the results obtained by rearranging the values of r / h and the value of as parameters are shown. If r is small, the larger H is, the more T
Becomes smaller, but when r is larger, the opposite tendency occurs.

FIG. 6 shows the results obtained by using the values of r / h and H / h as parameters for the equivalent value C of the area ratio of the depression. Also in this case, when r is small, T becomes smaller as C becomes larger, but when r is large, the opposite tendency occurs.

FIG. 7 shows the results obtained by rearranging the value of C as a parameter with respect to the value r / h corresponding to the height of the roughness of the base surface between the depressions. If the value of r / h is larger than a certain value, the value of T increases in the gap, and the larger the value of C, the smaller the value of r / h.
At h, T increases.

From this study, it is understood that the friction loss is reduced by the surface roughness shape according to the present invention for the following reasons.

Since the flow resistance is inversely proportional to the cube of the gap,
Even if there is a large depression, the flow of the lubricating oil always passes through the narrow part, and the flow resistance increases, and the closest approach distance between the sliding surfaces to obtain the same flow resistance as the smooth surface is very small. No. However, since the presence of the depression necessarily reduces the flow resistance, the closest approach distance is always closer than in the case of a smooth surface. On the other hand, the presence of the depression enlarges the area of the portion where the shear rate (the product of the reciprocal of the gap and the relative speed) is small. Therefore, as a result, the effect of increasing the area of the portion having a small shear rate due to the presence of the dent is greater than the increase in the shear rate of the portion where the closest approach distance is reduced, and the overall friction loss is reduced. Therefore, if the roughness height of the base surface between the depressions is large, the flow resistance due to the presence of the depression is reduced, and the effect of reducing the closest approach distance is the effect of increasing the area of the portion with a small shear rate due to the presence of the depression. More than
Conversely, the presence of the depression increases friction. Since the friction is inversely proportional to the gap, it can be seen that as r approaches the oil film thickness h, the effect of the increase in friction increases. In other words, the flow resistance to the pressure gradient with respect to the direction of the flow leaking from the gap in the gap shape between the two parts formed by the two surface shapes is the same as the flow resistance in the gap shape in which the two surfaces are formed to be completely smooth. It can be seen that in the same state, when the value obtained by dividing the reciprocal of the gap between the two parts by area is smaller than the value of the gap shape formed by the completely smooth surface, the friction loss is reduced.

Therefore, when the sum of the maximum heights of the irregularities on the smooth surface around each of the two depressions is smaller than the oil film thickness, if d <L, the larger the depth of the depression, the more the friction loss Is reduced. In addition, when the sum of the maximum heights of the irregularities on the smooth surface around the two depressions is smaller than the oil film thickness, if d <L, the shape between the two parts formed by the two surface shapes When the flow resistance with respect to the pressure gradient in the direction of the flow leaking from the gap in the gap shape of the above is in a state where the flow resistance is equal to the flow resistance in the gap shape in which the two surfaces are formed by completely smooth surfaces, the reciprocal of the gap between the two parts is determined. That is, the value obtained by dividing the area is smaller than the value obtained by the gap shape formed by the completely smooth surface.

In this embodiment, the sum of the maximum heights of the irregularities on the base surface around the two depressions is 1.5 μm, which is smaller than the oil film thickness, so that the friction can be reduced. As is clear from the principle, the relationship between the sizes of the depressions is not limited to that shown here, but d (= 20 μm).
It can be seen that m) is also effective as the diameter of the depression on the bearing side. In other words, when the sum of the maximum heights of the irregularities of the base surface around the two depressions is smaller than the oil film thickness,
The condition of d <L is a condition for obtaining the effect of the present invention, and is a feature of the present invention.

Also, if the size of the depression is large and larger than the range in which the fluid lubricating oil film is generated, it is obvious that the effect is lost in consideration of the above principle. In addition, even if the depth of the dent is deeper than necessary, friction does not decrease, and if the volume of the dent is too large, the compressibility of the lubricating oil appears,
It is also conceivable that the closest approach distance of the component surface is reduced.

In addition, from the principle of the above operation and effect, any sliding portion is lubricated between two surfaces that move relative to each other with a lubricant, which is a fluid, and the flow of the lubricating oil between the components is laminar. With respect to the surface shapes of the two components that slide while supporting a certain load, it is clear that the above-described configuration provides the operational effects shown in the above-described embodiment. Further, in this embodiment, the two dimples are formed as independent dimples having a substantially spherical shape by irradiating a laser beam. However, even if the dimples have an irregular shape as shown in FIG. It is also clear in principle that the same effect can be obtained as long as it is possible.

Also, as in this embodiment, one of the components,
Here, when the hardness of the bearing metal is smaller than the hardness of the other part, here, the crankshaft, if there is direct contact, the surface on the bearing metal side is scraped off due to wear. At this time, as shown in this embodiment, by setting the diameter of the harder dent as d and giving a relation of d <L, even if the d is small, the dent is less likely to disappear due to wear, and L is smaller. Since the setting can be made smaller, this relationship does not collapse even if the ratio of the dent on the bearing side is set to a large value.By increasing the diameter of the dent on the low hardness side, the time for the dent itself to disappear due to wear can be extended. The effect of reducing friction can be maintained for a long time. Furthermore, if the familiarization effect at the initial stage of operation is expected, even if the maximum height of the unevenness of the base surface around the depression on the bearing metal side is larger than the initial oil film thickness, if the maximum height of the unevenness becomes smaller than the oil film thickness after the completion of the adaptation, it is considered An effect equivalent to that of the embodiment can be obtained.

Further, for example, in the case of a crank bearing or a piston sliding surface of an internal combustion engine for an automobile, the relative sliding speed may exceed 20 m / s at the time of maximum rotation of the engine. Under such conditions, the oil film thickness becomes small due to the viscosity decrease due to the temperature rise based on the sliding friction heat generation, and the frequency of direct contact increases due to the elastic deformation of the parts due to the inertial force acting on the parts. Become. Also, in other mechanisms,
If direct contact between components occurs due to, for example, the entry of foreign matter during such high-speed sliding, the sliding speed is high, and there is a local cooling action to ensure the seizure resistance of the component. It is effective for By forming a dimple-shaped depression as in this embodiment, a certain amount of lubricating oil can be present in the depression, and a cooling effect can be expected. In addition, the contaminants can be trapped in the depressions to reduce direct contact between components.

In particular, for a crankshaft bearing of an internal combustion engine for an automobile under a high-speed and high-temperature condition, the above-described cooling effect is obtained for an engine operated under conditions in which the oil film thickness is smaller than normal operating conditions. It is also effective for improving the abrasion resistance due to the improvement of the substantial viscosity.

When considering only the crank bearing of an internal combustion engine for an automobile, the oil film thickness under normal operating conditions does not greatly deviate from the value shown in this embodiment. A common effect is obtained by the numerical value of.

(Embodiment 2) The above operation and effect can be similarly obtained in other sliding members and other sliding parts. For example,
As shown in FIG. 8, the surface shapes of the sliding surfaces of the cylinder bore 35 and the piston ring 36, and the cylinder bore 35 and the piston skirt 37 of the internal combustion engine are formed in the same relationship with respect to the oil film thickness value. Then, a similar effect can be obtained. Furthermore, since the piston slides back and forth with respect to the cylinder, at the top and bottom dead center where sliding stops,
The ability to form a fluid lubricating oil film decreases, the oil film thickness decreases, and direct contact increases. At this time, the presence of the dimple-shaped depression on the sliding surface as described above allows
Local cooling and continuous supply of the lubricant to the fracture surface of the boundary film become possible, and wear resistance and scuff resistance can also be improved.

Furthermore, if the internal combustion engine is limited to that for the automobile, the sliding speed is relatively high under the normal operating conditions, so that the oil film thickness at the stroke center portion where the friction loss contribution is large is: 8 piston skirts
μm and the piston ring is about 1 μm. Therefore, for example, the following surface shape can reduce the friction loss. If limited to those for automobiles, the oil film thickness under normal operating conditions does not greatly deviate from the values shown here, so that a common effect can be obtained by adopting the surface shape of the above numerical value. .

That is, the cylinder bore is made of a cast iron material, is formed to a hardness of about Hv300 by heat treatment or the like, the piston skirt is made of an aluminum alloy and has a hardness of about Hv150, and the piston ring is plated with chrome.
Its surface hardness is about Hv1000.

First, the cylinder bore is polished by a honing process, and has an average roughness Ra of 0.13 μm and a maximum height Ry of very fine cross-shaped polishing grooves.
(T): A flat surface (base surface) of 1 μm was formed.
Then, by irradiating this plane with a pulsed laser beam using a YAG laser device, a depth of 3 to 5 μm is applied.
m, diameter 10-30 μm, average value 20 μm (d = 20 μm)
m), a dimple-like depression having a substantially spherical shape with a pitch of 60 to 100 μm and an average value of 80 μm (the average value of the minimum distance between the depressions L = 30 μm) was formed.

With respect to the piston ring, the average roughness Ra of the same cross-shaped polished grooves by the same processing is Ra: 0.
By irradiating a similar YAG laser to a plane (base surface) of 13 μm and maximum height Ry (t): 1 μm,
Depth 3-5 μm, diameter 10-30 μm, average value 20 μm
(D = 20 μm), and a dimple-like depression having a substantially spherical shape with an area ratio of 30 to 80% was formed.

Further, with respect to the piston skirt, after forming the above-mentioned smooth surface (base surface) by grinding, the smooth surface is irradiated with a pulsed YAG laser to obtain an average value of 13 μm at a depth of 10 to 15 μm. , Diameter 50-80 μm, average value 60 μm, pitch 110-1
A depression having an average value of 150 μm at 80 μm (average value L of the minimum distance between the depressions L = 30 μm) was similarly formed.

In the above, the relationship d (ring) <L (bore) is established between the cylinder bore and the piston ring, and the relationship d (bore) <L (skirt) is established between the cylinder bore and the piston skirt. Friction loss can be reduced.

Further, by adopting the following surface shape, friction loss can be reduced, and the following effects can be obtained.

That is, by using the same material and the same processing method as described above, depressions of the same size are formed on the sliding surfaces of the cylinder bore, the piston ring, and the piston skirt, and the average of the minimum distance between the depressions in the piston skirt is determined. The value L1 was 30 μm, the pitch of the depressions in the piston ring was 60 to 100 μm, the average value was 80 μm, and the average value L2 of the minimum distance between the depressions was 30 μm. That is,
d (bore) <L1 (skirt) and d (bore) <L2
(Ring) is characterized in that the diameter of the depression of the cylinder bore is formed smaller than the other depressions.

In the center portion of the stroke of the cylinder bore, when the ring and the skirt slide at that position, the sliding speed is relatively high, so that the oil film thickness is relatively large. Therefore, abrasion hardly occurs. Therefore, even if the hollow of the cylinder bore is formed small, it is unlikely that the hollow will disappear due to wear. Therefore, since the depression of the cylinder bore can be formed small, the ratio of the depression on the ring and the skirt can be increased while maintaining the relation of d (bore) <L1 (skirt) and d (bore) <L2 (ring). Even if the recesses on the ring and skirt become smaller due to wear, the effect of reducing the friction loss can be maintained for a long time.

(Embodiment 3) An example in which the surface roughness structure of a sliding part according to the present invention is applied to a sliding surface of a piston skirt and a cylinder bore of an internal combustion engine for an automobile will be described. The internal combustion engine here has a displacement of about 2000 cc,
A motor having a maximum rotation speed of about 6000 rpm will be described.

The piston skirt slides at a high speed with respect to the cylinder bore, and the stroke direction is reversed at the top dead center and the bottom dead center. In the vicinity of the reverse position, the sliding parts are instantaneously exposed to boundary lubrication, but the contribution of friction loss is large in the center of the stroke, and in the center of the stroke, the lubricating oil is sufficiently supplied. The fluid lubricating oil film is formed because the fluid is supplied and the relative motion at high speed is constantly generated. Normal operating conditions frequently used, that is, 2000 rpm, 1/2000, which are operating conditions in which the frequency of operation is high and friction loss contributes to fuel consumption in this embodiment is large.
Under the four-load operation condition, the oil film thickness at the center of the stroke where the friction loss contribution is large is about 8 μm between the piston skirt and the cylinder bore, and about 1 μm between the piston ring and the cylinder bore.

Here, as shown in FIG. 9, a fine groove perpendicular to the sliding direction is formed on a smooth base surface 20 having a maximum height t (Ry) of 0.5 μm on the surface of the cylinder bore. 21 are formed. The depth H ′ _{1 to N} of the groove 21 is 3 to 5 μm, the average value H ′ is 4 μm, and the width b _{1 to N} is 1
0 to 30 μm, the average value b is 20 μm, the pitch P ′ _{1 to N} of the groove 21 is 50 to 100 μm, the average value P ′ is 80 μm, the average value L ′ of the minimum distance between the grooves is 60 μm,
The area ratio of the groove 21 is 10 to 60%.

On the other hand, similarly, grooves 21 orthogonal to the sliding direction are formed on the surface of the piston skirt, and the base surface 20 between these grooves has a maximum height t (R) of the unevenness.
y) is a smooth surface of 1.0 μm. About the said groove | channel 21, the depth H1- _N is 10-15 micrometers,
The average value H is 13 μm, the width B _{1 to N} is 50 to 80 μm, the average value B is 60 μm, and the pitch P is 1
The average value P is 150 μm, and the average value L of the minimum distance between the grooves is 90 μm.

The cylinder bore is made of cast iron material.
The hardness is adjusted to about Hv300 by heat treatment or the like, and the piston skirt is made of an aluminum alloy, and its hardness is about Hv150. The cylinder bore was polished by honing to obtain an average roughness Ra of 0.03 μm, which is composed of extremely fine and cross-shaped polishing grooves.
m, the maximum height t (Ry): after forming an extremely smooth base surface 20 of 0.5 μm,
By irradiating the AG laser, the grooves 21 having the above dimensions which do not intersect with the other grooves were formed at the above intervals. Further, as for the piston skirt, the base surface 2 having the above irregularities (maximum height t = 1.0 μm) is formed by grinding, and the surface is turned to form the grooves 21 having the above dimensions and intervals. Formed so as not to intersect with the groove. Table 1 summarizes the dimensions of the grooves 21 formed on the sliding surfaces of the cylinder bore and the piston skirt in this manner.

[0055]

[Table 1]

In the cylinder bore and the piston skirt having such a surface roughness, the lubricating oil film formed between the sliding surfaces receiving the load is characterized by the flow rate of the lubricating oil in the clearance caused by the reciprocation of the piston, Is determined by the balance with the flow rate leaking from the gap by the pressure caused by the pressure. In this embodiment, under the operating conditions of 2000 rpm and 1/4 load, which are the operating conditions in which the frequency of operation is high and the friction loss has a large effect on the fuel consumption, the oil film thickness is considered as a perfect smooth surface. h
= 8 μm, the balance is obtained. then,
The oil that is about to leak from the gap flows through the space formed by the surface shapes of the two sliding surfaces, and flows more from the portion where the flow resistance is small. Since the flow is laminar, the flow rate of the lubricating oil is proportional to the cube of the gap. Therefore, if there is a continuous space with a large gap in the flow direction, the flow resistance is greatly reduced. In this embodiment, since b <L, there is a very small probability that the groove is connected even if the groove is located between the two surfaces. Therefore, there is a possibility that a space with a large gap is continuous in the sliding direction. Almost no oil that escapes from the gap leaks out of the contact area along the groove 21 or the base surface 20 between the grooves in the cylinder bore and the base between the grooves in the piston skirt. It has to pass through a relatively narrow flow path between the surface 20. This has the effect of increasing the flow resistance of the oil that tends to leak from the gap, as compared with the conventional cross hatched surface shape.
As a result, even when the overall unevenness is large, the closest approach distance between the sliding surfaces is not reduced, and the fluid shear force at the concave portion is reduced without increasing the fluid shear force at the tip of the roughness. Can be reduced.

In the case of this embodiment, the description will be made in the same manner as in the first embodiment. That is, under the condition of b <L, the lubricating oil leaking along the groove is sufficiently large compared to the interval between the grooves, and most of the oil flow passes through a narrow portion of the gap distribution. Fig. 1 shows the gap distribution
Considering a two-dimensional shape like 0, it can be approximated by resistance to laminar pressure flow orthogonal to that shape. This flow resistance was calculated with respect to the roughness shape, and an approach state between the two surfaces, which was the same as the flow resistance when the oil film thickness was h = 8 μm, was determined by considering a completely smooth surface. If the roughness shape of the base surface between the grooves is considered to be three-dimensionally random, the flow resistance can be approximated in a smooth case, so that it was made smooth. The state of proximity between the two surfaces corresponds to the sliding state of the two surfaces under the operating conditions.

The friction loss due to shear sliding at that time can be approximated as being proportional to the reciprocal area of the oil film thickness.
Here, the roughness shape of the base surface between the grooves has a large effect on the reciprocal of the oil film thickness and cannot be ignored. Therefore, the sum of the reciprocals of the oil film thickness was calculated for the shape obtained by combining the random roughness shape and the fine groove shape of the base surface between the grooves. FIG. 4 shows an example of the cumulative distribution of the height of the combined roughness when the roughness shape is changed, and shows parameters obtained by organizing the calculation data.

The value corresponding to the height of the roughness of the base surface between the grooves is represented by r, the value corresponding to the depth of the groove is represented by H, and the value equivalent to the area ratio of the groove is represented by C. Arranged by these parameters, the reciprocal area value T of the oil film thickness corresponding to the friction loss and the value of T on a perfectly smooth surface having the same flow resistance as Tsmooth are shown in FIGS. Show.

FIG. 5 shows the results obtained by rearranging the value of r / h and the value of r / h as parameters with respect to the value H / h corresponding to the depth of the groove. When r is small, T increases as H increases, but when r is large, the opposite tendency occurs.

FIG. 6 shows the results obtained by using the values of r / h and H / h as parameters for the equivalent value C of the groove area ratio. Also in this case, when r is small, T becomes smaller as C becomes larger, but when r is large, the opposite tendency occurs.

FIG. 7 shows the results obtained by rearranging the value of C as a parameter with respect to the value r / h corresponding to the roughness height of the base surface between the grooves. If r / h is larger than a certain value, T
Is larger, and the larger the value of C is, the smaller r / h
Then, T increases.

From the above, it can be understood that the friction loss is reduced by the surface roughness shape of this embodiment for the following reason.

Since the flow resistance is inversely proportional to the cube of the gap,
Even if there is a large recess, the shape is such that the flow of the lubricating oil always passes through the narrow part, and by increasing the flow resistance, the closest approach distance of the component surface to obtain the same flow resistance as the smooth surface Is not so small. But,
Since the presence of the groove necessarily reduces the flow resistance, the closest approach distance is always closer than in the case of a smooth surface. On the other hand, the presence of the groove increases the area of a portion where the shear rate (the product of the reciprocal of the gap and the relative speed) is small. Therefore, as a result, the effect of increasing the area of the portion having a small shear rate due to the presence of the groove is greater than the increase in the shear rate of the portion where the closest approach distance is reduced, and the overall friction loss is reduced. Therefore, when the roughness height of the base surface between the grooves is large, the flow resistance due to the presence of the grooves is reduced, and the effect of reducing the closest approach distance is the effect of increasing the area of the portion where the shear rate is small due to the presence of the grooves. And conversely, the presence of the groove increases the friction. Since the friction is inversely proportional to the gap, it can be seen that as r approaches the oil film thickness h, the effect of the increase in friction increases. In other words, the flow resistance to the pressure gradient with respect to the direction of the flow leaking from the gap in the gap shape between the two parts formed by the two surface shapes is the same as the flow resistance in the gap shape in which the two surfaces are formed to be completely smooth. It can be seen that in the same state, when the value obtained by dividing the reciprocal of the gap between the two parts by area is smaller than the value of the gap shape formed by the completely smooth surface, the friction loss is reduced.

Therefore, when the sum of the maximum heights of the irregularities on the smooth surface around the two grooves is smaller than the oil film thickness, if b <L, the larger the groove area, the deeper the friction loss. Is reduced. Further, when the sum of the maximum heights of the irregularities of the smooth surface around the two grooves is smaller than the oil film thickness, if b <L, the two parts formed by the two surface shapes are formed. When the flow resistance with respect to the pressure gradient in the direction of the flow leaking from the gap of the gap shape is equal to the flow resistance in the gap shape in which the two surfaces are formed by completely smooth surfaces, the reciprocal of the gap between the two parts is determined. That is, the value obtained by dividing the area is smaller than the value obtained by the gap shape formed by the completely smooth surface.

In this embodiment, the sum of the maximum heights of the irregularities on the base surface around the two grooves is 1.5 μm, which is smaller than the oil film thickness of 8 μm, so that the friction can be reduced. As is clear from the principle, the relationship between the groove sizes is not limited to that shown here, and it can be seen that there is an effect when b is set as the width of the groove of the piston skirt.
That is, when the sum of the maximum heights of the irregularities of the base surface around the two grooves is smaller than the oil film thickness, the condition of b <L is a condition for obtaining the effect of the present invention,
This is a feature of the present invention.

If the width of the groove is larger than the range in which the fluid lubricating oil film is generated, it is obvious that the effect is lost in consideration of the above principle. Also, even if the depth of the groove is deeper than necessary, friction does not decrease.If the volume in the groove is too large, the compressibility of the lubricating oil appears, and the closest approach distance of the component surface may be reduced. Can be

Also, from the principle of the above operation and effect, any sliding portion is lubricated between the two surfaces that move relative to each other with a lubricant that is a fluid, and the flow of the lubricating oil between the components is a laminar flow. With respect to the surface shapes of the two components that slide while supporting a certain load, it is clear that the above-described configuration provides the operational effects shown in the above-described embodiment.

Also, as in this embodiment, one of the components,
Here, the hardness of the piston skirt is
Here, when the hardness is smaller than the cylinder bore, if there is direct contact, the surface on the piston skirt side is scraped off due to wear. At this time, as in this embodiment, by setting the diameter of the hard dent as b and giving the relationship of b <L, even if it is small b, the groove is less likely to disappear due to wear, and L is small. Since it can be set small, this relationship does not collapse even if the groove ratio on the piston skirt side is set to be large, and by increasing the width of the groove on the soft side, the time that the groove itself disappears due to wear can be extended, The effect of reducing friction can be maintained for a long time. In addition, if the effect of adaptation at the initial stage of operation is expected, even if the maximum height of the unevenness of the base surface between the grooves on the piston skirt side is initially larger than the oil film thickness, it can be made smaller than the oil film thickness after the adaptation. In this case, the same effect as that of the embodiment can be obtained.

Further, for example, in the case of a piston sliding surface of an internal combustion engine for an automobile, the relative sliding speed can exceed 20 m / s at the time of maximum rotation of the engine. Under these conditions,
Due to the viscosity decrease due to the temperature rise due to the sliding friction heat generation, the oil film thickness decreases, and the frequency of direct contact increases due to the elastic deformation of the component due to the inertial force acting on the component. Also, even if other mechanisms are used, if direct contact between parts occurs due to, for example, entry of foreign matter during such high-speed sliding, the sliding speed is high, so that there is a local cooling action. Is effective for securing the seizure resistance of the component. By forming the groove-shaped concave portion as in this embodiment, a predetermined volume of lubricating oil can be present in the groove, so that a cooling effect can be expected. Further, the contaminated foreign matter can be captured in the groove to reduce direct contact between components. In addition, because of the reciprocating sliding, at the upper and lower dead center where sliding stops, the ability to form a fluid lubricating oil film is reduced, the oil film thickness is reduced, and direct contact is more likely to occur. At this time, the presence of the groove-shaped concave portion on the sliding surface as described above enables local cooling, continuous supply of the lubricant to the fracture surface of the boundary film, and also provides wear resistance and scuff resistance. Can be improved.

The above operation and effect can be obtained by using other sliding parts, for example,
The same effect can be obtained by forming the surface shape on the sliding surface between the cylinder bore and the piston ring of the internal combustion engine in a similar relationship to the value of the oil film thickness.

Further, if the internal combustion engine is limited to that for the automobile, the sliding speed is relatively high under the normal operating conditions, so that the oil film thickness at the stroke center portion where the friction loss contribution is large is 8 piston skirts
μm and the piston ring is about 1 μm. Therefore, for example, the following surface shape can reduce the friction loss.

In other words, the cylinder bore has a maximum height t (R
y): On the smooth base surface 20 of 0.5 μm, a depth of 3 to
A groove 21 having a thickness of 5 μm, a width of 10 to 30 μm (average value b = 20 μm), a pitch of 60 to 100 μm (average value: 80 μm), and an average value L ′ of the minimum distance between grooves of 60 μm is formed.

As for the piston skirt, as described above, the depth is 10 to 15 μm (average value: 13 μm), and the width is 50 to 8 μm.
0 μm (average value: 60 μm), pitch 110 to 180 μ
m (average value: 150 μm), average value L of minimum distance between grooves
Form a groove 21 of 90 μm.

The piston ring is plated with chrome and has a surface hardness of about 1000 Hv. The piston ring is polished by a honing process to obtain an average roughness of very fine and cross-shaped polished grooves. It was a smooth plane with Ra: 0.03 μm and maximum height Ry: 0.5 μm.

If the oil film thickness between the piston ring and the cylinder bore is 1.0 μm and the piston ring has no groove, but if the distance between the grooves is infinite, b <L
Is established, the sliding contact width between the piston ring and the cylinder bore is about 0.5 mm, and the contact width a is sufficiently larger than b + L ′ obtained by adding the groove width b ′ of the cylinder bore to the groove width L ′. Therefore, the friction loss can be reduced between the cylinder bore and the piston ring as in the case between the cylinder bore and the piston skirt. As described above, since the relationship of b + L '<a is established between the cylinder bore and the piston ring, and b (bore) <L (skirt) is established between the cylinder bore and the piston skirt, the effect of reducing the friction loss can be maintained for a long time. Can be.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing shapes and structures of a bearing metal and a crankshaft. (B) It is a perspective view which shows the bearing box which accommodated the bearing metal shown in FIG. 1 (a). (C) It is a horizontal sectional view about line CC in Drawing 1 (a).

FIGS. 2 (a), (b) and (c) are perspective views and plan views respectively showing fine shapes of a sliding surface of a crankshaft and a bearing metal (aluminum alloy, Hv100) as sliding parts according to the present invention. It is a figure and a sectional view.

FIG. 3 is a schematic view in which the surface shape shown in FIG. 2 is regarded as a two-dimensional shape.

FIG. 4 is a graph showing a cumulative distribution of roughness height.

FIG. 5 is a graph showing a relationship between a value H / h corresponding to a depth of a concave portion and a friction loss.

FIG. 6 is a graph showing the relationship between the equivalent value C of the area ratio of the concave portion and the friction loss.

FIG. 7 is a graph showing a relationship between a value r / h corresponding to a roughness height of a base portion and a friction loss.

FIG. 8 is a schematic diagram showing a cylinder bore, a piston ring, and a piston skirt in the internal combustion engine.

FIGS. 9 (a), (b) and (c) are a perspective view, a plan view and a sectional view, respectively, showing fine shapes of sliding surfaces of a cylinder bore and a piston skirt as sliding parts according to the present invention.

FIG. 10 is a schematic view in which the surface shape shown in FIG. 9 is regarded as a two-dimensional shape.

FIG. 11 is a graph showing a sliding surface shape of a conventional crankshaft.

FIG. 12 is a schematic view showing a surface shape of a conventional piston skirt.

FIGS. 13A and 13B are schematic diagrams showing the surface shape of the inner surface of a conventional cylinder bore.

[Explanation of symbols]

 10, 20 Base surface 11 Depression 21 Groove 31 Bearing metal 32 Crank 35 Cylinder bore 36 Piston ring 37 Piston skirt

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02F 5/00 F02F 5/00 N F16C 17/00 F16C 17/00 Z 33/10 33/10 Z F16J 1/04 F16J 1/04 9/26 9/26 C (72) Inventor Makoto Kano 2-term Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 3G024 AA22 AA23 AA24 AA55 EA01 FA06 FA07 FA14 GA16 GA17 GA18 GA21 HA01 3J011 AA07 BA02 CA10 DA02 JA02 KA02 KA07 MA02 NA01 PA02 QA17 RA03 3J044 AA02 AA04 AA12 BA01 BB39 BB40 BC04 BC07 CB13 CC03 DA09

Claims (30)

[Claims] 1. A surface roughness structure of two parts sliding relative to each other in an internal combustion engine and lubricated with lubricating oil in a state of laminar flow between the sliding surfaces. In the formed gap between the two parts, the flow resistance to the pressure gradient in the flow direction of the lubricating oil leaking from the gap is equal to the flow resistance in the gap formed between the two parts when both sliding surfaces are completely smooth. A sliding component, wherein a value obtained by dividing the reciprocal of the gap between the two components by area is smaller than a value in a gap shape formed by a completely smooth surface in the same state. 2. A base surface in which both sliding surfaces have irregularities of the maximum height t, a dimple-shaped depression surrounded by the base surface, and the maximum depth of the depression in each sliding surface is determined. When H, H / t is greater than 1, the maximum diameter of the dent on both sliding surfaces is less than the shortest span of the sliding surface, and the average of the maximum diameter of the dent on one sliding surface is d. When the average value of the minimum distance between the depressions on the other sliding surface is L, d
The sliding component according to claim 1, wherein <L is satisfied. 3. A surface roughness structure of two parts sliding relative to each other in an internal combustion engine and lubricated with a lubricating oil in a laminar flow state between the sliding surfaces, wherein both sliding surfaces have a maximum height. The base surface having the irregularities of the height t has a dimple-shaped dent which is entirely surrounded by the base surface, and a gap formed between the two parts when both sliding surfaces are completely smooth surfaces. When the inflow of lubricating oil due to the relative motion and the outflow of lubricating oil due to the pressure generated between the two parts are balanced, the closest approach distance between the sliding surfaces is defined as h. At least one of the average depths of the depressions on each sliding surface is larger than h, and the maximum diameter of the depressions on both sliding surfaces is less than the shortest span of the range in which the lubricating oil film is formed. The average value of the maximum diameter of the dent of the moving surface is d, and the average value of the minimum distance between the dents of the other sliding surface is L. Wherein d <L. 4. The average value of the maximum diameter of the depression on the sliding surface having the higher surface hardness of both sliding surfaces is d, and the average of the minimum distance between the depressions on the sliding surface having the lower surface hardness is d. 4. The sliding component according to claim 3, wherein when the value is L, d <L. 5. When the average value of the maximum diameter of the dent on the sliding surface with the lower surface hardness of both sliding surfaces is D,
5. The method according to claim 3, wherein D> d.
The sliding parts described. 6. The unevenness of the base surface of the sliding surface having the lower surface hardness, wherein the maximum height of the unevenness of the base surface is smaller than h on the sliding surface having the higher surface hardness of the two sliding surfaces. 4. The maximum height of the slab is greater than h.
A sliding component according to claim 5. 7. The method according to claim 7, wherein h is calculated under the condition that has the greatest effect on friction loss among the operating conditions assumed in the reciprocating internal combustion engine equipped with the sliding component. The sliding component according to any one of claims 3 to 6. 8. A value h0 calculated as h0 calculated under a condition having the largest effect on friction loss among operating conditions assumed in a reciprocating internal combustion engine equipped with the sliding component.
The sliding component according to any one of claims 3 to 7, wherein h under other operating conditions may be smaller than h0. 9. Among the operating conditions assumed in the reciprocating type internal combustion engine equipped with the sliding parts, the condition having the largest effect on the friction loss is defined as the rotation of 1/3 of the maximum rotation speed and 1 / of the maximum load. 8. The condition of item 4 is satisfied.
Or the sliding component according to claim 8. 10. The operating condition for the longest operating time assumed in a reciprocating internal combustion engine equipped with the sliding component is set to a rotation of 1/3 of the maximum rotation speed and 1/4 of the maximum load.
9. The condition described in claim 7 or claim 8.
The sliding parts described. 11. The component having a higher surface hardness of the sliding surface is a crankshaft, and the component having a lower surface hardness is a bearing metal supporting the crankshaft. Item 11. The sliding component according to any one of Items 10. 12. Both parts are for an internal combustion engine for an automobile, wherein the maximum height of the unevenness of the base surface on the crankshaft sliding surface is 1 μm or less, and the average depth of the depression is 1 to 50 μm.
The sliding component according to claim 11, wherein the average depth of the depression in the bearing metal sliding surface is 1 to 50 m, and the average value of the maximum diameter is 1 mm or less. 13. The component according to claim 3, wherein the component having the higher surface hardness of the sliding surface is a cylinder bore, and the component having the lower surface hardness is a piston skirt. The sliding parts described. 14. Both parts are for an internal combustion engine for an automobile, wherein the maximum height of the unevenness of the base surface on the sliding surface of the cylinder bore is 1 μm or less, and the average depth of the depression is 1 to 50 μm.
The average depth of the depressions on the piston skirt sliding surface is 1 to 50 μm, and the average value of the maximum diameter is 1 mm.
The sliding component according to claim 13, wherein: 15. The component according to claim 3, wherein the component having the higher surface hardness of the sliding surface is a piston ring, and the component having the lower surface hardness is a cylinder bore. The sliding parts described. 16. Both parts are those of an internal combustion engine for automobiles, wherein the maximum height of the irregularities on the base surface on the piston ring sliding surface is 1 μm or less, and the average depth of the depressions is 1 to 50 μm.
The sliding component according to claim 15, wherein the average depth of the depression in the sliding surface of the cylinder bore is 1 to 50 m, and the average value of the maximum diameter is 1 mm or less. 17. The component according to claim 3, wherein the component having the higher surface hardness of the sliding surface is a cylinder bore, and the component having the lower surface hardness is a piston ring. The sliding parts described. 18. Both parts are those of an internal combustion engine for an automobile, wherein the maximum height of the unevenness of the base surface on the cylinder bore sliding surface is 1 μm or less, and the average depth of the depression is 1 to 50 μm.
The sliding component according to claim 17, wherein the average depth of the depressions on the piston ring sliding surface is 1 to 50 µm, and the average value of the maximum diameter is 1 mm or less. 19. A surface roughness structure at a portion where a piston skirt and a piston ring of an internal combustion engine slide with a cylinder bore, and the piston skirt and the piston ring under the condition that the operation time assumed in the internal combustion engine is longest. Assuming that the sliding surface between the cylinder bore and the cylinder bore is a completely smooth surface, the amount of lubricating oil flowing in and the amount of lubricating oil flowing out due to the pressure generated between the parts and the relative movement into the gap formed between the parts. H is the closest approach distance between the sliding surfaces when the balance is made, and the smaller value of h on the two sets of sliding surfaces of the piston skirt and the cylinder bore and the piston ring and the cylinder bore at the center of the piston vertical movement stroke. Where h is the sliding surface of the cylinder bore and piston ring has a smaller maximum height irregularity The base surface has a dimple-shaped depression entirely surrounded by the base surface, the depth of the depression is larger than h, and the average value of the maximum diameter of the depression is the width of the sliding surface of the piston ring. In addition, the sliding surface of the piston skirt has a dimple-shaped dent which is entirely surrounded on the base surface having irregularities of the maximum height smaller than h, and the depth of the dent is greater than h,
When the average value of the maximum diameter of the depression of the cylinder bore is d, the average value of the minimum distance between the depressions of the piston skirt is L1, and the average value of the minimum distance between the depressions of the piston ring is L2, d <L1 and d <Sliding component characterized by L2. 20. A surface roughness structure of a sliding surface of a cylinder bore, a piston skirt and a piston ring of an internal combustion engine, wherein the sliding surface of the cylinder bore has a base surface having a maximum height of 1 μm or less. The base surface is entirely surrounded, has a depth of 1 to 50 μm, and has an average value d of maximum diameter of 50 μm or less. The sliding surface of the piston skirt that slides on the cylinder bore has a maximum height of 5 μm.
A base surface having the following irregularities is entirely surrounded by the base surface, has a depth of 1 to 50 μm, and has an average maximum diameter of 1
mm, and the sliding surface of the piston ring that slides in contact with the cylinder bore is surrounded by a base surface having a maximum height of 1 μm or less, and is entirely surrounded by the base surface and has a depth of 1 to 1. Assuming that there is a depression of 50 μm and the average of the maximum diameter is 50 μm or less, the average of the minimum distance between the depressions of the piston skirt is L1, and the average of the minimum distance between the depressions of the piston ring is L2, d < L1 and d <L2
A sliding part characterized by the following. 21. A surface roughness structure of two parts sliding relative to each other in an internal combustion engine and lubricated with a lubricating oil in a laminar flow state between the sliding surfaces, wherein each of the sliding surfaces has a maximum. The base surface having irregularities of heights t1 and t2 (μm) has a plurality of grooves that form an angle of 45 ° or more with the sliding direction without intersecting each other. H (μm)
H / t1 and H / t2 are greater than 1, the maximum width of the groove is less than or equal to the contact length in the sliding direction where the lubricating oil film is formed, and the average of the maximum width of the groove on one sliding surface is A sliding component, wherein b <L when the value is b (μm) and the average value of the minimum distance between grooves on the other sliding surface is L (μm). 22. When both sliding surfaces are completely smooth,
The closest approach distance between the sliding surfaces when the amount of lubricating oil flowing in due to relative movement into the gap formed between the parts and the amount of lubricating oil flowing out due to the pressure generated between the two parts is defined as h. 22. The surface roughness structure of a sliding component according to claim 21, wherein said t1 and t2 are smaller than h. 23. An average value of the maximum width of the groove on the sliding surface having the higher surface hardness of the two sliding surfaces, and an average of the minimum distance between the grooves on the sliding surface having the lower surface hardness. Value is L
3. The method according to claim 2, wherein b <L.
A sliding component according to claim 1 or claim 22. 24. When the average value of the maximum width of the groove on the sliding surface with the lower surface hardness of both sliding surfaces is B,
The sliding component according to claim 22, wherein B> b. 25. The method according to claim 25, wherein h is calculated under the condition having the largest effect on friction loss among the operating conditions assumed in the reciprocating internal combustion engine equipped with the sliding component. Item 22 to Item 24
A sliding component according to any one of the above. 26. The component according to claim 22, wherein the component having the higher surface hardness of the sliding surface is a cylinder bore, and the component having the lower surface hardness is a piston skirt. The sliding parts described. 27. Both parts are those of an internal combustion engine for an automobile, and the unevenness of the base surface on the sliding surface of the cylinder bore and the piston skirt is 1 μm or less in maximum roughness indication Ry, and the average of the grooves in the cylinder bore is Depth is 1
The average value of the minimum distance between the grooves is 50 μm or less, and the average depth of the grooves in the piston skirt is 5 to 50 μm, and the average value of the minimum distance between the grooves is 1 mm or less. 27. The sliding component according to 26. 28. An inflow of lubricating oil due to relative movement into a gap formed between said parts when a sliding surface between a piston skirt and a piston ring and a cylinder bore is assumed to be completely smooth. Let h be the closest approach distance between the sliding surfaces when the amount of lubricating oil flowing out due to the generated pressure is balanced, and two sets of a piston skirt and a cylinder bore and a piston ring and a cylinder bore at the center of the piston vertical movement stroke. The smaller value of h on the sliding surface is h0, the average value of the maximum width of the groove in the cylinder bore is b, the average value of the minimum distance between the grooves is L ′, and the minimum value of the minimum distance between the grooves in the cylinder bore is When the average value is L and the contact width in the sliding direction between the piston ring and the cylinder bore is a, the piston skirt, the piston ring, and the cylinder The maximum height of the irregularities of the base surface in the authors at h0 less, and b> L, b + L '<claim 23 through claim, characterized in that a relation of a 27
A sliding component according to any one of the above. 29. A base surface in a sliding surface of a piston skirt, a piston ring, and a cylinder bore has irregularities of a maximum height of 1 μm or less, respectively, and an average value b of a maximum width of a groove in the cylinder bore is 1 to 50 μm; The average depth of the groove is 1 to 10 μm, the average value L ′ of the minimum distance between the grooves is 100 μm or less, the average value B of the maximum width of the groove in the piston skirt is 50 μm or more, and the average depth of the groove is 5 to 50 μm.
μm, average value L of minimum distance between grooves is 50 μm or more and 1 mm
The sliding component according to claim 28, wherein: 30. A surface roughness structure of two parts sliding relative to each other in an internal combustion engine and lubricated with lubricating oil in a state of laminar flow between the sliding surfaces, wherein the two parts have different surface roughness. In the formed gap between the two parts, the flow resistance to the pressure gradient in the flow direction of the lubricating oil leaking from the gap is equal to the flow resistance in the gap formed between the two parts when both sliding surfaces are completely smooth. An internal combustion engine characterized by using a sliding part whose value obtained by dividing the reciprocal of the gap between two parts by area is smaller than the value of the gap shape formed by a completely smooth surface when the two parts are in the same state.