JP2010236649A - Combination of piston ring and cylinder or cylinder liner, and piston ring used in the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston ring suitably used in a combination with a cylinder or a cylinder liner having a sliding surface structure reducing reciprocating friction. <P>SOLUTION: The piston ring is formed in an outer peripheral sliding surface of the piston ring with a plurality of grooves which each extend from one end cutting out an outer peripheral line of either end in a ring axis direction of the sliding surface to the other end lying in a plane of the sliding surface and are spaced from each other in a circumferential direction of the outer peripheral sliding surface of the piston ring. The piston ring is combined with the cylinder or the cylinder liner formed with a number of recesses in the inner wall surface of the cylinder or cylinder liner. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piston ring disposed on a piston that slides in a cylinder and a combination of the piston ring and a cylinder or a cylinder liner, and more specifically, has a sliding surface structure capable of reducing reciprocating friction. The present invention relates to a compression ring used in combination with a cylinder or a cylinder liner, and more particularly to a first compression ring.

Environmental issues such as global warming have been greatly highlighted on a global scale, and the development of fuel efficiency improvement technology for internal combustion engines to reduce CO _{2 in} the atmosphere has become a major issue. Reduction of the friction loss of the sliding member is required. In view of this, in recent years, the development of sliding member materials, surface treatment, and modification technologies that are excellent in wear resistance and seizure resistance and that can maximize the effect of reducing frictional force have been developed. It is being advanced.

  In order to improve the energy efficiency of a device using a cylinder, such as an improvement in fuel consumption of an internal combustion engine, reduction of friction loss is effective. In particular, friction reduction is effective between the piston ring that reciprocates and the inner wall surface of the cylinder. In order to reduce the reciprocating friction, it is said that reducing the surface roughness of the inner wall surface of the cylinder is an effective means. However, if the surface roughness is too small, the lubricating oil retained on the inner wall surface will be reduced. Since it almost disappeared, there was a problem that seizure resistance was lowered. In order to improve seizure resistance, in Patent Document 1, the cylinder liner is formed such that the surface roughness of the inner wall surface thereof becomes rougher from the top dead center side to the bottom dead center side of the piston.

  Patent Document 2 discloses a technique for reducing the reciprocating friction between the piston ring and the cylinder liner by forming a recess in the inner wall surface of the cylinder liner. In Patent Document 2, the cylinder liner is divided into a plurality of regions in the axial direction of the cylinder depending on the difference in sliding speed, and the shape of the indentation is different for each region, thereby enhancing the effect of reducing the reciprocating friction. .

  As disclosed in Patent Document 2, forming a large number of recesses on the inner wall surface of a cylinder or cylinder liner is effective in reducing frictional force in sliding between the cylinder or cylinder liner inner wall surface and a piston ring. Bring. Hereinafter, such an inner wall surface provided with a large number of recesses will be referred to as a “multi-concave bore”.

  However, among the piston rings attached to the piston, for oil rings with a small width per sliding surface, such a multi-concave bore has a great effect of reducing the frictional force, but on the compression ring, it slides. It has been found that the effect of such an effect is not sufficiently exhibited because the width per surface is wider than that of an oil ring.

  In particular, the phenomenon becomes remarkable in the combination of the first compression ring and the case where the dent volume and the dent area in the multi-concave bore are small.

  However, so far, when combined with a multi-concave bore, an effective solution has been found that can enjoy the frictional force reduction effect provided by the multi-concave bore even in a compression ring such as the first compression ring. Absent. Therefore, even if such a multi-concave bore is adopted, the overall reduction in friction loss is limited, and the improvement in energy efficiency of the device using the cylinder, such as improvement in fuel consumption of the internal combustion engine, is not much. The current situation was not.

JP-A-8-200135 JP 2007-46660 A

  The present invention has been made in view of the above problems, and a piston suitably used in combination with a cylinder or cylinder liner having a sliding surface structure capable of reducing reciprocating friction, that is, a multi-concave bore. The main purpose is to provide a ring.

  The present invention further provides a compression that can enjoy the friction reducing effect of the multi-concave bore when combined with a cylinder or cylinder liner having a sliding surface structure capable of reducing reciprocating friction, that is, a multi-concave bore. An object of the present invention is to provide a ring, particularly a first compression ring, and to provide a combination of a cylinder or a cylinder liner and a piston ring, which is excellent in such a friction reducing effect.

  As a result of repeated studies in view of the problems in the prior art as described above, the present inventors, as described above, have a piston ring having a large width per sliding surface and a small concave volume in a multi-concave bore. Since the disappearance of the frictional force reduction effect due to the multi-concave bore becomes remarkable when this is combined, this disappearance action is closely related to the pressure in the recess and the discharge of the lubricating oil staying in this recess. Reached an opinion. On the other hand, the length of the concave portion provided in the bore in the cylinder axial direction is not more than the dimension of the compression ring, at least the axial width (h1) of the first compression ring, from the viewpoint of securing the sealing performance on the sliding surface. It is essential. Therefore, it is impossible to improve the pressure and oil discharge performance of the recess by increasing the length of the recess in the bore axis direction.

  Under such circumstances, the present inventors have made further investigations and researches, and as a result, the compression ring is provided with a groove having a unique pattern as described below on the outer peripheral sliding surface of the compression ring. The multi-concave bore is improved by improving the oil discharge performance when the compression ring comes into contact with the recess of the multi-concave bore and reducing the effect of oil film pressure without deteriorating the gas sealing performance of the ring. The present inventors have found that the friction reducing performance can be further extracted and have reached the present invention.

  That is, the present invention for solving the above-mentioned problem is that the surface of the sliding surface is formed from one end portion of the outer peripheral sliding surface of the piston ring, in which one end peripheral line in the ring axis direction of the sliding surface is notched. In the circumferential direction of the outer periphery sliding surface of the piston ring, a plurality of recesses are formed in the piston ring and the inner wall surface of the cylinder or cylinder liner. A cylinder or cylinder liner combination.

Further, the groove in the piston ring has a length (Ls _y ) in the axial direction of the piston ring of the groove, the axial length of the piston ring is h1, and each recess provided on the inner wall surface of the cylinder or cylinder liner. When the length of the cylinder or cylinder liner in the axial direction is Ld _y , it is desirable that the following relational expression is satisfied.
Ls _y ≦ H−Ld _y (1)

  Further, a plurality of the grooves are provided spaced apart from each other in the circumferential direction of the outer peripheral sliding surface of the piston ring, and cut one end outer peripheral line in the ring axial direction of the outer peripheral sliding surface of the piston ring. A groove having one end portion lacking and a groove having one end portion notching the other end portion outer peripheral line in the ring axial direction of the outer peripheral sliding surface of the piston ring may be arranged from both sides.

Further, as described above, a plurality of the grooves are provided apart from each other in the circumferential direction of the outer peripheral sliding surface of the piston ring, and one end portion in the ring axial direction of the outer peripheral sliding surface of the piston ring. A groove (first opening end groove) having one end cut out of the outer circumferential line and a groove (second opening end) cut out from the outer circumferential line of the other end in the ring axial direction of the outer peripheral sliding surface of the piston ring Groove) is arranged from both sides, a circumferential gap distance (Ds _x ) between the adjacent first opening end groove and second opening end groove is provided on the inner wall surface of the cylinder or cylinder liner. When the length of each recessed portion in the circumferential direction of the cylinder or cylinder liner is Ld _x , the following relational expression may be satisfied.
Ld _x <Ds _x (2)

Furthermore, as described above, a plurality of the grooves are provided apart from each other in the circumferential direction of the outer peripheral sliding surface of the piston ring, and one end of the outer peripheral sliding surface of the piston ring in the ring axial direction is provided. A groove (first opening end groove) having one end cut out of the outer circumferential line and a groove (second opening end) cut out from the outer circumferential line of the other end in the ring axial direction of the outer peripheral sliding surface of the piston ring Groove) is arranged from both sides, a circumferential gap distance (Ds _x ) between the adjacent first opening end groove and second opening end groove is provided on the inner wall surface of the cylinder or cylinder liner. Ld _x represents the length of each recessed portion in the circumferential direction of the cylinder or cylinder liner, and the total width of the two recessed portions adjacent in the circumferential direction at the same height position in the axial direction of the cylinder or cylinder liner (two (Including the gap distance between the recesses) Lwd _x may satisfy the following relational expression.
Ld _x <Ds _x <Lwd _x (3)

  The present invention for solving the above-mentioned problems is also provided along the circumferential direction of the ring from the one end portion of the outer peripheral sliding surface of the piston ring that cuts out one circumferential end portion outer edge line facing the joint of the ring. Extends and cuts out the other circumferential edge of the ring facing the joint of the ring, or is in the plane of the sliding surface and has a width of 1.0 mm or less to the other end and a depth of 0.001 to 0 A plurality of recesses are formed in the piston ring in which a plurality of 2 mm grooves are provided apart from each other in the axial length direction of the outer peripheral sliding surface of the piston ring, and the inner wall surface of the cylinder or cylinder liner. A cylinder or cylinder liner combination.

Further, at least one of the plurality of convex portions formed by being surrounded by the outer peripheral line of the end surface of the outer peripheral sliding surface of the piston ring and the edge line of the groove is the length of the convex portion in the axial direction of the piston ring ( It is desirable that Lb _y ) satisfy the following relational expression, where Ld _y is the length in the axial direction of the cylinder or cylinder liner of each recess provided on the inner wall surface of the cylinder or cylinder liner.
Lb _y > Ld _y (4)

In the present invention, the piston ring may be a compression ring, particularly a first compression ring.
In the present invention, the cylinder or the cylinder liner further includes at least an uppermost piston ring at the bottom dead center of the piston from a lower surface position of a ring groove of the lowest piston ring at the top dead center of the piston. It may be a cylinder or a cylinder liner in which a large number of recesses are formed in the central region of the stroke, which is the region between the upper surface of the ring groove.

The present invention further shows a piston ring used in a combination of the above-described piston ring and a cylinder or a cylinder liner.

  According to the present invention, when combined with a multi-concave bore, even in a compression ring such as a first compression ring, the frictional force reduction effect brought about by the multi-concave bore can be fully enjoyed, thereby improving the fuel efficiency of the internal combustion engine. For example, the energy efficiency of the apparatus using the cylinder can be greatly improved.

It is the perspective view and explanatory drawing which show an example of a structure of the piston ring of 1st invention. It is explanatory drawing which shows another shape of the groove | channel provided in the piston ring of 1st invention. It is explanatory drawing which shows the relationship between the length of the groove | channel provided in the piston ring of 1st invention, and the recessed part formed in the cylinder inner wall surface facing this. It is explanatory drawing which shows the relationship between the space | interval between the grooves provided in the piston ring of 1st invention, and the recessed part formed in the cylinder inner wall surface facing this. It is the perspective view and explanatory drawing which show an example of a structure of the piston ring of 2nd invention. It is explanatory drawing which shows another shape of the groove | channel provided in the piston ring of 2nd invention. It is explanatory drawing which shows the relationship between the groove | channel provided in the piston ring of 2nd invention, and the recessed part formed in the cylinder inner wall surface facing this. It is explanatory drawing which shows an example of the formation position of the recessed part of the inner wall face of the cylinder liner which comprises the cylinder combined with the piston ring of this invention. It is explanatory drawing which shows an example of the range of a stroke center part area | region in the cylinder combined with the piston ring of this invention. It is a general | schematic expanded view which shows the example of the shape of the recessed part formed in the cylinder combined with the piston ring of this invention. It is a general | schematic expanded view which shows an example of arrangement | positioning of a recessed part in the cylinder combined with the piston ring of this invention. It is the general | schematic expanded view and schematic sectional drawing explaining the dimension position of the recessed part formed in the cylinder combined with the piston ring of this invention. It is the schematic sectional drawing and schematic developed drawing explaining the area ratio in the cylinder combined with the piston ring of this invention. It is the schematic which shows the dimension of the cylinder liner used in the Example of this invention. In the Example of this invention, it is a schematic sectional drawing which shows the structure of the apparatus used in order to measure reciprocating friction. It is a graph which shows the measurement result in the Example of this invention. It is explanatory drawing which shows the shape of the groove | channel of an undesirable piston ring.

  Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings.

  The piston ring according to the present invention is formed from one end portion (hereinafter also referred to as “opening end portion”) in which one end outer peripheral line in the ring axial direction of the sliding surface is notched on the outer peripheral sliding surface of the ring. A piston ring provided with a groove (hereinafter also referred to as “axial groove”) that reaches the other end (hereinafter also referred to as “in-plane end”) in the plane of the sliding surface. (Hereinafter also referred to as “piston ring of the first invention”).

  Another piston ring according to the present invention has one end portion (hereinafter also referred to as a “first opening end portion”) cut out from an outer peripheral sliding surface of the ring, and one circumferential end portion outer edge line facing the joint of the ring. )), And the other end portion (hereinafter also referred to as “second opening end portion”) extending along the circumferential direction of the ring and notching the other circumferential end portion outer edge line facing the joint of the ring. Alternatively, a piston ring provided with a groove (hereinafter also referred to as “circumferential groove”) reaching the other end portion (hereinafter also referred to as “in-plane end portion”) within the sliding surface. (Hereinafter also referred to as “piston ring of the second invention”).

  The piston ring according to the first invention and the piston ring according to the second invention are both internal combustion engines such as automobile and airplane engines, external combustion engines such as Stirling engines, and engines other than heat engines such as compressors. The present invention can be applied to any piston ring that is mounted on a piston in all reciprocating engines, including a compression ring, and more particularly, for example, a first compression ring and a second compression ring that are often used in an internal combustion engine. When applied as a first compression ring having a large contact width in a combination of three piston rings, ie, a ring and an oil control ring, it exhibits a preferable function and effect.

  Furthermore, the piston ring according to the first invention and the piston ring according to the second invention are both cylinders or cylinder liners formed with a large number of recesses in the inner wall surface, in particular at least the inner wall surface of the cylinder or cylinder liner, In the center area of the stroke, which is the area from the lower surface position of the ring groove of the lowest piston ring at the top dead center of the piston to the upper surface position of the ring groove of the uppermost piston ring at the bottom dead center of the piston, The function and the effect are exhibited in combination with a cylinder or cylinder liner formed with a large number of recesses, that is, a multi-concave bore. The structure of this type of cylinder or cylinder liner will be described in detail later.

  In general, when a piston ring is combined with a multi-concave bore, when the piston ring is positioned at a position where it abuts against a concave portion of the multi-concave bore, the length of the concave portion in the cylinder axial direction is the seal on the sliding surface. From the viewpoint of securing the property, since the dimension of the compression ring, at least the first compression ring, is equal to or less than the dimension of the axial width (h1), the concave portion is substantially formed by the sliding surface of the piston ring that abuts. There is a period of time in the position of being completely occluded. At that time, the sliding surface of the piston ring receives the surface pressure of the lubricating oil, which is a substantially incompressible fluid that stays excessively in the recess, and the frictional resistance increases.

  However, in the piston ring according to the first aspect of the present invention, the opening end portion that cuts off the outer peripheral line at any end in the ring axis direction of the sliding surface reaches the in-plane end portion in the plane of the sliding surface. Since it has a groove, lubricating oil that excessively stays in the concave portion passes through the in-plane end portion or in-plane groove path of the groove of the ring that comes into contact with the sliding surface of the piston ring from the open end portion. Since it is discharged to the outside, an increase in surface pressure due to the lubricating oil remaining excessively in the concave portion as described above is avoided, and the friction reducing performance due to the multi-concave bore is sufficiently exhibited without increasing the frictional resistance. It will be.

  On the other hand, the groove provided in the piston ring according to the first invention is not formed to communicate over the entire length in the ring axial direction of the sliding surface of the ring, that is, both ends become open end portions, and the sliding It does not form a passage that penetrates the moving surface in the ring axis direction, and the other end remains in the surface, ensuring gas sealing at the sliding contact interface between the piston ring and the multi-concave bore. It is what is done.

  Also in the piston ring according to the second aspect of the invention, from the first opening end portion that cuts out one circumferential end portion outer edge line facing the ring joint, it is extended along the circumferential direction of the ring, Since the other circumferential end outer edge line facing is cut out, or a groove reaching the other end (second opening end or in-plane end) in the plane of the sliding surface is provided, the first As in the case of the piston ring according to the invention, the excessively retained lubricating oil in the concave portion passes through the in-plane end portion or in-plane groove path of the groove in contact with the ring from the open end portion of the piston ring. Since it is discharged out of the sliding surface, an increase in surface pressure due to the lubricating oil that stays excessively in the recesses as described above is avoided, and the friction reducing performance by the multi-concave bore is sufficient without increasing the frictional resistance. It will be demonstrated in

  Further, the groove provided in the piston ring according to the second invention is provided along the circumferential direction of the sliding surface of the ring, and the opening end portion is positioned at the abutment of the ring, and the axial direction of the ring Therefore, the gas sealability at the sliding contact interface between the piston ring and the multi-concave bore is also ensured.

  Further, both the axial groove as formed in the piston ring of the first invention and the circumferential groove as formed in the piston ring of the second invention are engaged with each other. The piston ring according to the first aspect of the invention and the piston ring according to the second aspect of the invention may be provided in the same manner as described above, and the friction reducing performance due to the combined multi-concave bore is sufficient. On the other hand, the gas sealing property at the sliding contact interface between the piston ring and the multi-concave bore is ensured.

(Piston ring of the first invention)
Next, the piston ring according to the first invention will be described in detail.
FIG. 1 is a perspective view and an explanatory view showing a configuration in an embodiment of the piston ring of the first invention.

  In the piston ring 1 of the embodiment shown in FIGS. 1A and 1B, the outer peripheral sliding surface 2 has a first end outer peripheral line in the ring axial direction (y direction in the figure) of the sliding surface. 3a (upper side in the drawing) from one end portion 4a to the other end portion 4b in the surface of the sliding surface 2, and the sliding surface in the ring axis direction (y direction in the drawing) The groove 5 extending from the one end 5a that cuts off the end peripheral line 3b (lower side in the figure) to the other end 5b in the plane of the sliding surface 2 is the circumference of the outer peripheral sliding surface of the piston ring. In the direction, a plurality are provided spaced apart from each other.

  In the embodiment shown in FIG. 1, a groove 4 (hereinafter referred to as “upper groove 4”) extending in-plane from the first end portion outer peripheral line 3 a in the ring axis direction of the sliding surface of the ring, and the ring. Grooves 5 (hereinafter referred to as “lower side grooves 5”) extending in the plane from the second end outer peripheral line 3b in the ring axis direction of the sliding surface of the sliding surface are alternately arranged in the circumferential direction. However, in the piston ring according to the first invention, the outer peripheral line of the end portion in the ring axial direction (y direction in the figure) of the sliding surface that is the opening end of the grooves 4 and 5 is the first or first Any one of the end peripheral lines 3a and 3b of 2 has no particular problem. For example, as shown in FIG. 2 (a) showing another embodiment, a plurality of grooves provided in the circumferential direction are all formed by the upper groove 4 or as shown in FIG. 2 (b). In addition, any of a plurality of grooves provided in the circumferential direction may be configured by the lower groove 5. Further, even when the upper side groove 4 and the lower side groove 5 are mixed, the grooves 4 and 5 are not necessarily arranged alternately as shown in FIG. 1, for example, FIG. As shown in FIG. 4, the grooves 4, grooves 4, grooves 5, grooves 5, grooves 4, grooves 4... Are arranged in order of two, or in order of three or more permutations. It may be arranged in a completely random order.

In addition, such a groove shape of the grooves 4 and 5 is also within the surface of the sliding surface from one end portion of the ring sliding surface of the ring in the ring axis direction from which one of the outer peripheral lines 3a and 3b is cut out. As long as the shape reaches the other end portion located, it is not particularly limited, and extends along the ring axial direction of the sliding surface of the ring as in the grooves 4 and 5 shown in the embodiment shown in FIG. As shown in FIG. 2 (d), not only those that are inclined with respect to the ring axis direction of the sliding surface of the ring, those that form a curved groove as shown in FIG. 2 (e), 2 (f) to (i), the groove is branched in the middle, and the other end located in the plane of the sliding surface is two or more, and FIGS. k), on the contrary, a plurality of ends on the inner surface of the sliding surface are assembled or connected to form a ring shaft on the sliding surface of the ring. A plurality of opening end portions in which the outer peripheral lines 3a and 3b in the direction are cut out, and those in which the groove width is not constant as a whole as shown in FIGS. 2 (l) and (m). It can be set as the thing of this aspect.
In FIGS. 2A to 2M, the piston ring is shown in a straight line for simplicity of illustration, but naturally this is of a ring shape. That will be easily understood.

  However, the grooves 4, 5 are in-plane within the plane of the sliding surface 2 from the open end portions 4 a, 5 a that cut out any of the outer peripheral lines 3 a, 3 b in the ring axis direction of the sliding surface. It is necessary to reach the end portions 4b and 5b, and the groove is extended from one end portion outer peripheral line 3a to the other end outer periphery line 3b, that is, as shown in FIG. There is a groove extending over the entire length of the sliding surface of the piston ring in the ring axis direction, and both ends thereof do not become the open ends 204a and 204b. Thus, when the groove 204 penetrates in the ring axis direction of the piston ring 201, gas leakage occurs through the through groove 204 when the piston ring is used in a reciprocating engine, and the sealing performance by the piston ring is generated. This is because it becomes impossible to secure.

As described above, the piston ring 1 of the first invention is preferably used in combination with a multi-concave bore, but the groove 4 (5) provided in the piston ring is formed by the groove as shown in FIG. The length of the piston ring in the axial direction (Ls _y ) is the length of the piston ring in the axial direction of the ring h1, and each recess 6 provided on the inner wall surface of the cylinder or cylinder liner in the axial direction of the cylinder or cylinder liner. when the length and Ld _y, it is desirable that satisfy the following relationship.
Ls _y ≦ h1-Ld _y (1)

That is, suppose that the length (Ls _y ) of the groove 4 (5) in the axial direction of the piston ring is equal to the axial length (h1) of the piston ring 1 and the axial direction of the cylinder or cylinder liner of the recess 6. As shown in FIG. 3, depending on the positional relationship between the piston ring 1 and the recess 6, if the difference between the length (Ld _y ) and the groove 4 (5) and the recess 6, the piston ring 1 This is because a channel having a length exceeding the axial length (h1) of 1 is formed, and gas leakage through the channel may occur.

In the piston ring of the first invention, the length (Ls _y ) of the grooves 4 and 5 in the axial direction of the piston ring is not particularly limited, and the axial length of the piston ring 1 in which the groove is provided. Although it depends on (h1) and the size of the concave portions formed on the multi-concave bore used in combination, specifically, for example, it can be about 0.1 to 3.0 mm.

  Furthermore, even if the passage area itself of the axial grooves 4 and 5 provided in the piston ring of the first invention is very small, it functions sufficiently. This is because the oil that is the object flowing in the groove can be regarded as a substantially incompressible fluid. Note that the oil discharge capacity increases as the passage increases, so the width and depth are not limited in terms of function, but can be set as appropriate in consideration of the sealing performance, structural strength, etc. of the piston ring. desirable. Although not particularly limited, specifically, for example, the groove width is 0.005 to 2.0 mm, more preferably about 0.01 to 1.0 mm, and the depth is 0.001 to 0.2 mm. More preferably, the thickness can be about 0.001 to 0.1 mm. Regarding the depth, there is a possibility that it may become a base point of breakage depending on the direction of the groove, so it is appropriate to keep it within a range of about 0.2 mm.

  In the piston ring according to the first aspect of the present invention, the presence of at least one of the grooves 4 and 5 functions significantly. However, depending on the arrangement of the recesses 6 formed in the multi-concave bore used in combination, the piston ring In the circumferential direction of one outer peripheral sliding surface, a plurality of them are provided apart from each other as in the embodiments shown in FIGS. 1 and 2 (a) to (c) described above. It is more significant that it is.

As in the embodiment shown in FIGS. 1 and 2 (c), both the upper side groove 4 (first opening end groove) and the lower side groove 5 (second opening end groove) are arranged in the piston ring. In this case, the circumferential gap distance (Ds _x ) between the adjacent upper groove 4 and lower groove 5 is a cylinder or cylinder liner of a recess 6 formed in a multi-concave bore used in combination as shown in FIG. When the length in the circumferential direction is Ld _x , it is desirable that the following relational expression is satisfied.
Ld _x <Ds _x (2)

That is, when the circumferential gap distance (Ds _x ) between the adjacent upper grooves 4 and lower grooves 5 is smaller than the circumferential length (Ld _x ) of the recess 6 or the cylinder liner, the piston ring 1 Depending on the positional relationship of the recesses 6, as shown in FIG. 4, the adjacent grooves 4, 5 and the recesses 6 positioned therebetween have a flow path with a length exceeding the axial length (h 1) of the piston ring 1. This is because gas leakage through the flow path may occur.

Further, in this case, when the total width (including the gap distance between the two recesses) of the two recesses 6 adjacent in the circumferential direction at the same height position in the axial direction of the cylinder or cylinder liner is Lwd _x . It is more desirable to satisfy the following relational expression.
Ld _x <Ds _x <Lwd _x (3)

That is, when the circumferential gap distance (Ds _x ) between the adjacent upper groove 4 and lower groove 5 is greater than the total width of the recess 6 (including the gap distance between the two recesses) Lwd _x , This is because the grooves 4 and 5 cause a recess 6 that cannot discharge oil.

  The shape of the outer peripheral sliding surface of the piston ring itself is not particularly limited, and may be any known form. For example, the desired groove as described above may be formed on the outer peripheral sliding surface of the first compression ring in a three-ring configuration (two compression rings and one oil control ring). As oil control rings, there are known two-piece oil control rings consisting of a coil expander and an oil control ring body, and three-piece oil control rings consisting of two side rails and a spacer expander. The groove according to the present invention can also be formed on the outer peripheral sliding surface of the oil control ring.

(Piston ring of the second invention)
Next, the piston ring according to the second invention will be described in detail.
FIG. 5 is a perspective view and an explanatory view showing a configuration in an embodiment of the piston ring of the second invention.

  In the piston ring 51 of the embodiment shown in FIGS. 5 (a) and 5 (b), one end portion of the outer peripheral sliding surface 52 cut out from one circumferential end portion outer edge line 58a facing the ring mating port 57. (The first opening end) 54a is extended along the circumferential direction of the ring (x direction in the figure), and the other circumferential end 58b of the other circumferential end facing the ring mating port 57 is cut to the other end. A plurality of grooves 55 are provided so as to be spaced apart from each other in the axial direction of the piston ring 51.

  In the embodiment shown in FIG. 5, both end portions 54 a and 54 b of the groove 55 are open end portions that cut out the circumferential end portion outer edge lines 58 a and 58 b facing the ring joint 57. Only one of the circumferential grooves provided in the piston ring according to the second invention may be an open end, and the other may be an in-plane end located in the plane of the sliding surface. . FIG. 6A is a diagram showing an embodiment in which such one has a groove that is an in-plane end, and one of the outer peripheral sliding surfaces 62 of the piston ring 61 faces the ring joint 67. Other than the one end portion (first opening end portion) 64a that cuts out the circumferential edge portion outer edge line 68a along the circumferential direction (x direction in the drawing) of the ring, and the other in the plane of the sliding surface 62 of the ring From the groove 65a reaching the end portion 64b and the one end portion (first opening end portion) 64c that cuts out the other circumferential end portion outer edge line 68b facing the ring joint 67, the ring circumferential direction (x direction in the figure) ) And a groove 65b extending in the plane of the sliding surface 62 of the ring and reaching the other end 64d.

  Thus, when the circumferential groove provided in the piston ring of the second invention is an in-plane end portion with one end in the plane as shown in FIG. The direction length is not particularly limited, but in the axial direction of the piston ring (y direction in the figure) so that the groove of any of the grooves exists over almost the entire circumferential direction of the piston ring. It is desirable that several grooves be combined and arranged at the same height or at a nearby height. Preferably, as in another embodiment shown in FIGS. 6 (b) and 6 (c), the piston rings are aligned so that there is a groove over the entire peripheral surface (excluding the space of the abutment). A groove 65a having a groove extending from one circumferential end edge line 68a facing the mouth 67 and a groove extending from the other circumferential edge line 68b facing the mating hole 67 And a groove 65b having a phase difference in the axial direction of the piston ring, and the groove paths of the plurality of grooves 65a and 65b overlap at least partially in the circumferential direction, or in-plane end portions of the plurality of grooves It is desirable to arrange so that 64b and 64d are coincident at a certain circumferential position.

  Of course, in one piston ring, for example, as shown in FIG. 6 (d), a groove 55 whose both ends are open ends and grooves 65a and 65b whose only ends are open ends are combined. It is also possible.

  Furthermore, the groove path of the circumferential groove 65 provided in the piston ring of the second invention is located within the sliding surface of the piston ring, that is, one of the end outer peripheral lines 63a in the ring axis direction of the sliding surface, As long as 63b is not cut out, the sliding surface may be displaced in the ring axis direction as shown in another embodiment shown in FIGS.

  Further, the groove of the circumferential groove 65 provided in the piston ring of the second invention is located in the sliding surface of the piston ring, that is, any one of the outer peripheral lines 63a in the ring axial direction of the sliding surface, As long as 63b is not cut out, as shown in another embodiment shown in FIGS. 6 (g) to (h), it branches in the direction of the ring axis of the sliding surface in the middle of the groove and is in one or more planes. The form which has the branch end part 6 may be sufficient.

  6 (a) to 6 (h), in order to simplify the illustration, the piston ring is shown in a state of being stretched on a straight line, but naturally this is of a ring shape. That will be easily understood.

  Further, the circumferential groove provided in the piston ring of the second invention functions satisfactorily even if the passage area itself is very small, like the axial groove provided in the piston ring of the first invention. Note that the oil discharge capacity increases as the passage increases, so the width and depth are not limited in terms of function, but can be set as appropriate in consideration of the sealing performance, structural strength, etc. of the piston ring. desirable. Although not particularly limited, specifically, for example, the groove width is 0.005 to 2.0 mm, more preferably about 0.01 to 1.0 mm, and the depth is 0.001 to 0.2 mm. More preferably, the thickness can be about 0.001 to 0.1 mm. Regarding the depth, there is a possibility that it may become a base point of breakage depending on the direction of the groove, so it is appropriate to keep it within a range of about 0.2 mm.

  In the piston ring according to the second aspect of the present invention, the presence of even one circumferential groove significantly functions. However, in each of the embodiments shown in FIGS. 5 and 6A to 6C described above, As shown in the drawings, it is more significant that a plurality of piston rings are provided apart from each other in the axial direction of the piston ring, and as described above, any one of the substantially entire circumferential direction is provided. Desirably, there is a groove in the groove.

As described above, the piston ring of the second invention is also preferably used in combination with the multi-concave bore, but as shown in FIG. 7, the outer peripheral lines 73a and 73b of the outer peripheral sliding surface of the piston ring 71. , 78a and 78b and at least one of the plurality of convex portions 80a, 80b, 80c... Surrounded by the peripheral lines 79a, 79b, 79c, 79d. When the length (Lb _y ) in the axial direction of the ring is Ld _y when the length in the axial direction of the cylinder or cylinder liner of each recess 6 provided on the inner wall surface of the cylinder or cylinder liner is Ld _y It is desirable to satisfy.
Lb _y > Ld _y (4)

Although not particularly limited in this respect, the length (Lb _y ) in the axial direction of any of the convex portions 80a, 80b, 80c... On the sliding surface of the piston ring is the same as that of the cylinder or cylinder liner of the concave portion 6. If less than the length Ld _y in the axial direction, the sealing performance by the piston rings and there is a possibility that degraded.

  Note that the shape of the outer peripheral sliding surface of the piston ring itself is not particularly limited as in the first aspect of the invention, and any known form may be used, and the description thereof is omitted. .

(Multi-concave bore)
Next, a cylinder or cylinder liner (multiple uneven bore) formed by forming a large number of recesses on the inner wall surface, which is preferably used in combination with the above-described piston ring according to the present invention, will be described.

  The multi-concave bore may have a concave portion that functions to reduce the reciprocating friction between the two by reducing the area of the sliding contact interface with the piston ring according to the present invention as described above. There is no particular limitation.

  As described with respect to the piston ring according to the present invention, the multi-concave bore includes an internal combustion engine such as an automobile or airplane engine, an external combustion engine such as a Stirling engine, a cylinder other than a heat engine such as a compressor, or Any of the cylinder liners may be used.

  The multi-concave bore is composed of a cylinder body and a cylinder liner fixed to the inside of the cylinder body, and the piston slides on the inner wall surface of the cylinder liner. The inner wall surface and the inner wall surface of the cylinder in the “linerless type” in which the piston slides directly on the inner wall surface of the cylinder are included.

  Hereinafter, each of these modes (cylinder liner type and linerless type) will be described with reference to preferable modes.

(Cylinder liner type)
The cylinder liner type cylinder includes a cylinder body and a cylinder liner fixed to the inside of the cylinder body, and the plurality of recesses are formed on the inner wall surface of the cylinder liner. In this aspect, the inner wall surface of the cylinder body and the outer wall surface of the cylinder liner are fixed, and the piston slides on the inner wall surface of the cylinder liner. Therefore, the cylinder to which the cylinder liner is fixed The inner wall surface of the main body need not be provided with a recess.

Hereinafter, the cylinder of this aspect will be described with reference to the drawings.
FIG. 8 is an explanatory diagram showing an example of the formation position of the concave portion on the inner wall surface of the cylinder liner in the cylinder liner fixed to the inner wall surface of the cylinder body (not shown) of this aspect.

  As illustrated in FIG. 8, a plurality of recesses 6 are formed on the inner wall surface 102 of the cylinder liner 101 in this embodiment. The recess 6 is preferably formed only in the stroke center region 104 of the inner wall surface 102 of the cylinder liner 101, and is not formed in any region other than the region 104. The stroke center region 104 is a region between the lower surface position of the ring groove of the lowest piston ring at the top dead center of the piston and the upper surface position of the ring groove of the uppermost piston ring at the bottom dead center of the piston. is there.

  FIG. 9 is a schematic cross-sectional view showing an example of the range of the stroke center region 104 in the cylinder fixed to the inside of the cylinder main body of this aspect.

FIG. 9 is a cross-sectional view of the piston 121a at the top dead center stop position and the piston 121b at the bottom dead center stop position when the piston reciprocates. The stroke center region 104 is formed on the inner wall surface 102 of the cylinder liner 101 from the lower surface 124 position of the ring groove 123 of the lowest piston ring 122 of the piston 121a at the top dead center stop position, to the piston at the bottom dead center stop position. This is a region between the top surface 127 of the ring groove 125 of the uppermost piston ring 126 at 121b. FIG. 9 shows a piston in which three piston rings (first compression ring, second compression ring, and oil control ring) are used, and the lowest piston ring 122 is an oil control ring. The piston ring 126 is a first compression ring.
Here, the piston ring according to the present invention (the first invention or the second invention) described above is not particularly limited, but of these three piston rings, a compression ring (first compression ring, second compression ring). Compression ring), or at least the first compression ring.

  In order to improve the energy efficiency of the device in which the cylinder is used, for example, to improve the fuel efficiency of the engine, it is effective to reduce the friction loss between the piston ring and the inner wall surface of the cylinder (in this embodiment, the inner wall surface of the cylinder liner). It is. The method of reducing the friction loss differs depending on the sliding condition, but in particular, the piston has a feature such that the speed becomes 0 at the top dead center, and therefore, it varies depending on the sliding position. Therefore, in the cylinder liner constituting the cylinder of this aspect, the recess 6 is formed only in the stroke center region 104 of the inner wall surface, and at least one of the plurality of recesses 6 is formed in all cross sections in the cylinder circumferential direction. In other words, by forming the recesses 6 so as to overlap in the cylinder axis direction so that there are two recesses 6, it is possible to reduce the frictional force in the entire region of the stroke center region 104.

  In other words, the reciprocating friction can be reduced by reducing the surface roughness of the inner wall surface of the cylinder liner near the top dead center and the bottom dead center where the moving speed of the piston is relatively low. However, the influence of the shearing resistance of the lubricating oil increases in the stroke center region 104, which is a region where the sliding speed between the inner wall surface of the cylinder liner and the piston ring is high. Therefore, in this embodiment, by forming a recess only in the stroke center region 104 among the inner wall surface of the cylinder liner, the contact area between the piston ring and the inner wall surface of the cylinder liner is reduced, and the shear resistance of the lubricating oil is reduced. It becomes possible to reduce the influence of the.

  Here, when a plurality of recesses are formed randomly in the stroke center region 104, the contact area between the piston ring and the inner wall surface of the cylinder liner is small in the stroke center region 104 as a whole. The width of the sliding piston ring (the length in the axial direction of the piston ring) is very short compared to the stroke center region 104. Therefore, depending on the location, there may be a portion where no recess is formed, In this portion, the piston ring sliding surface and the inner wall surface of the cylinder liner are in contact with each other by 100%, and the above effect may not be sufficiently exhibited. Therefore, in a preferred embodiment, as described above, all cross sections in the circumferential direction of the cylinder have at least one of the plurality of recesses, in other words, the recesses overlap in the cylinder axial direction. By forming it, the sliding piston ring is always in contact with the recess. As a result, the contact area between the piston ring and the inner wall surface of the cylinder liner does not become 100%, and the above-described effects can always be exhibited.

<Recess>
Next, the recessed part formed in the inner wall surface of the cylinder liner which comprises the cylinder of this aspect is demonstrated.

  In this aspect, the shape of the recess formed on the inner wall surface of the cylinder liner is not particularly limited, and can be appropriately adjusted according to the arrangement of the recess. For example, as illustrated in FIGS. 10A to 10J, a concave portion having a shape constituted by a straight line and / or a curved line can be formed. The concave portions may be horizontally long as shown in FIGS. 10A to 10C, vertically long as shown in FIGS. 10D to 10G, or vertically as shown in FIGS. 10H to 10J. A shape with a substantially equal ratio of width to width may be used.

  In the cylinder of the preferred embodiment, as described above, at least one recess is formed in all cross sections in the cylinder circumferential direction in the stroke center region. Thereby, a contact area can be reduced efficiently and on average.

  As described above, when considering a cross section in the circumferential direction, if no recess is formed in a certain cross section, when the piston ring passes through the cross section, it passes through the cross section in which a plurality of recesses are formed. Compared to the case, the contact area between the piston ring and the inner wall surface of the cylinder liner is increased. Therefore, the influence of the shear resistance of the lubricating oil is increased, and as a result, the reciprocating friction is also increased.

  On the other hand, by forming at least one recess in all cross sections in the cylinder circumferential direction in the stroke center region, the contact area can be obtained even if the piston ring passes through any circumferential cross section in the stroke center region. Therefore, the reciprocating friction can be surely reduced.

  As an example of the state of “a state in which at least one of a plurality of recesses is formed in all cross sections in the circumferential direction of the cylinder”, which is a feature of this aspect, the case of FIGS. Can be mentioned.

  FIG. 11A is a schematic development view showing an example of the arrangement of the recesses 6 in the above-described stroke center region 104 of FIG. In FIG. 11A, the vertical direction of the drawing is the axial direction of the cylinder, and the horizontal direction of the drawing is the circumferential direction of the cylinder. As illustrated in FIG. 11A, in the line X drawn in the cylinder circumferential direction, the lowermost point 105a of the recess 6a is located below the uppermost point 106b of the recess 6b closest to the lower side. In the line Y drawn in the cylinder circumferential direction, the lowest point 105b of the recess 6b is positioned below the uppermost point 106c of the recess 6c closest to the lower part. In this way, by arranging the recesses close to each other in the vertical direction so as to overlap with each other in the cylinder axial direction, at least one of the plurality of recesses can be formed in all cross sections in the cylinder circumferential direction. From the above, when the piston reciprocates, the piston ring that slides in the central region of the stroke can reduce the contact area with the cylinder inner wall surface at any position in the cylinder axial direction, reducing reciprocating friction. There is an effect.

  FIG. 11B is a schematic development view showing an example of the arrangement of the recesses 6 in the stroke center region 104 of FIG. 9 described above, similarly to FIG. Also in FIG. 11B, the vertical direction of the drawing is the axial direction of the cylinder, and the horizontal direction of the drawing is the circumferential direction of the cylinder. In FIG. 11 (a), the recess 6 is formed with a uniform area over the cylinder axis direction. However, the present invention is not limited to this mode, and as shown in FIG. 11 (b), the cylinder axis direction The area of the recess 6 may be reduced in the vicinity of the end of the stroke center area 104, and the area of the recess may be increased in the vicinity of the center of the stroke center area 104.

  The dimensions of the recess are not particularly limited, and can be appropriately adjusted according to the dimensions of the cylinder and the piston ring used together. However, from the viewpoint of maintaining the airtightness of the cylinder, the average length in the cylinder axial direction of the concave portion is the axial length (h1) of the compression ring of the piston rings used, at least the uppermost piston ring ( It is preferable that it is below the axial length (h1) of a 1st compression ring. More specifically, it is preferable to set it to about 5 to 100% of the axial length (h1) of the uppermost piston ring among the piston rings used.

  The average length of the recesses in the cylinder circumferential direction is preferably within a range of 0.1 mm to 15 mm, and particularly preferably within a range of 0.3 mm to 5 mm. When the cylinder circumferential direction average length is less than this range, the effect of forming the concave portion may not be sufficiently obtained. On the other hand, if the circumferential average length exceeds this range, a part of the piston ring may enter the recess and a problem such as deformation of the piston ring may occur.

  The average length (depth) of the recess in the cylinder radial direction is preferably in the range of 0.1 μm to 1000 μm, more preferably in the range of 0.1 μm to 500 μm, and particularly preferably in the range of 0.1 μm to 50 μm. When the average length in the cylinder radial direction of the recess is less than this range, the effect of forming the recess may not be sufficiently obtained. On the other hand, when the radial average length exceeds this range, processing is difficult, and there is a problem such as the need to increase the radial length of the cylinder liner (thicken the wall thickness). There is.

  In this aspect, the cylinder circumferential direction average length (interval) between adjacent recesses is preferably in the range of 0.1 to 15 mm, and particularly preferably in the range of 0.3 mm to 5 mm. If the cylinder circumferential average length (interval) between adjacent recesses is less than this range, the inner wall surface of the cylinder liner on which the piston ring slides is too small, and the inner wall surface of the piston ring and the cylinder liner May not be able to slide stably. On the other hand, when it exceeds this range, the effect of forming the recess may not be sufficiently obtained.

  In addition, each average length of the recessed part mentioned in this aspect shall mean the average length of each location illustrated in FIG. FIG. 12A is a schematic development view showing the cylinder axial direction of the inner wall surface of the cylinder liner in the vertical direction of the drawing. FIG. 12B is a schematic cross-sectional view of the cylinder liner in the circumferential direction. The average axial length of the concave portion is an average length of the concave portion 6 in the cylinder axial direction as illustrated in FIG.

  Moreover, the circumferential direction average length of the said recessed part 6 is an average of the length of the recessed part 6 in a cylinder circumferential direction so that it may illustrate in Fig.12 (a). As illustrated in FIG. 12B, the average length in the circumferential direction of the recess 6 means the average length of the surface including the inner wall surface 102, and the same applies to the area of the recess.

  Moreover, the radial direction average length (depth) of the said recessed part 6 is the average of the length from the bottom face of the recessed part 6 to the inner wall face 102 of the cylinder liner 101 so that it may illustrate in FIG.12 (b). Moreover, the cylinder circumferential direction average length (interval) between the said recessed parts is the average of the space | interval of the adjacent recessed part 6 so that it may illustrate in FIG. 12 (a) and (b).

  As a particularly preferred form of the cylinder liner, a plurality of recesses are formed only in the stroke center area, and the total area of all recesses is 1 to 80% when the area of the stroke center area is 100%. The number of recesses formed per cross section in the cylinder circumferential direction is at least one. Furthermore, when the number of recesses formed in one cross section in the cylinder circumferential direction is too small, there is a possibility that the effect of reducing the reciprocating frictional force obtained by forming the recesses and reducing the contact area cannot be sufficiently obtained. is there. Therefore, it is preferable to form a recess that can sufficiently exhibit the effect for each cross section in the cylinder circumferential direction.

  The concave portion to which the effect of reducing the reciprocating frictional force is obtained differs depending on the reciprocating speed of the piston used together, but the area of the entire concave portion when the area of the central region of the stroke is 100%. The total is preferably 1 to 80%, more preferably 10 to 60%, and particularly preferably 20 to 50%. If the area ratio is less than this range, the effect of forming the recess may not be sufficiently obtained. On the other hand, if the area ratio exceeds this range, the contact area is too small, and the piston ring is in a cylinder liner. Inconveniences such as being unable to slide stably on the inner wall surface may occur. From the viewpoint of the effect of reducing the reciprocating frictional force, there is a preferable range of the size of the recess. Therefore, the number of recesses and the number of recesses are determined so that the area ratio is within the above range and at least one recess is formed in all cylinder circumferential cross-sections while taking into account the size of each recess. It is necessary to adjust the arrangement.

“The total area of all recesses when the area of the stroke center region is 100%” means that the area of the recesses 6 is A ₁ , A ₂ , as illustrated in FIGS. 13A and 13B. , _a 3, when the _{··· a n, a 1, a} 2, a 3 to the area of the stroke center region is intended to mean the ratio of the sum of the · · · _{a n.} The total area ratio, the area _A 1 of the recesses 6 in the stroke center _region, A _2, A 3, total ··· _{A n A total} and, the area of the inner wall surface 102 other than the concave portion 6 in the stroke center region B Using B _total, it is expressed by the following formula. As illustrated in FIG. 13A, the area of the recess 6 here means not the area of the bottom of the recess 6 but the area in the cross section including the inner wall surface 102.

  The shape, size, arrangement, area ratio, and the like of the recesses described above may be the same in all the central region of the stroke or may be different depending on the region. For example, in the stroke center region, the area ratio may be different in each region in the cylinder axis direction, the recessed area is small in the upper portion and the lower portion of the stroke center region, and in the center portion of the stroke center region. May have a large recessed area. The area ratio or the like may be changed stepwise or continuously.

<Cylinder liner>
The cylinder liner in this embodiment is used by being fixed inside the cylinder body, and a piston ring mounted on the piston slides on the inner wall surface. The dimensions, materials, and the like of the cylinder liner of this aspect can be appropriately designed in consideration of the dimensions and materials of the cylinder body, compatibility with the piston rings used together, and the operating temperature.
In this embodiment, from the viewpoint of reducing the reciprocating frictional force between the piston ring and the inner wall surface of the cylinder liner, the 10-point average roughness Rz of the portion where the recess is not formed in the central region of the stroke is 4 μm or less. Preferably, the thickness is 2 μm or less, more preferably 1 μm or less. Further, in this aspect, all the areas in which the piston slides have the surface roughness, such as the area near the top dead center, the area near the bottom dead center, and the center area of the stroke on the inner wall surface of the cylinder liner. It is preferable. The ten-point average roughness Rz is defined in JIS B0601-1994.

<Cylinder>
The cylinder body used in this embodiment is only required to be able to fix the cylinder liner to the inside thereof, and its material, dimensions, etc. can be appropriately designed according to the application, operating temperature and the like.

(Linerless type)
Next, the linerless type will be described. The linerless type cylinder does not use a cylinder liner as in the cylinder liner type, and the recess is formed directly on the inner wall surface of the cylinder body, and the piston slides directly on the inner wall surface of the cylinder. It moves.
This type of cylinder is the same as the cylinder liner type cylinder described above except that a cylinder liner is not used and a recess is formed directly on the inner wall surface of the cylinder body. Omitted. In other words, the stroke center region and the recess described in the cylinder liner type can be applied to the linerless type of this mode as it is, and the cylinder of this mode has a predetermined recess, desirably an inner wall, on its inner wall surface. By providing a predetermined recess in the stroke center region of the wall surface, the piston ring according to the present invention can be used in suitable combination.

(Combination of piston ring and multi-concave bore)
As described above, the piston rings of the first and second inventions are suitably combined with a cylinder or a cylinder liner having a recess on the inner wall surface as described above, particularly having a recess in the stroke center region of the inner wall surface. used. In such a combination, the piston rings of the first and second inventions may be at least one of a group of piston rings that slide on the inner peripheral surface of the cylinder or cylinder liner. At least one of the compression rings, and for example, in a three-ring configuration (two compression rings and one oil control ring), the first compression ring having the largest ring axial length is the first. By comprising the piston ring of the invention or the second invention, an excellent effect can be exhibited. In this case, as a matter of course, the second compression ring can also be constituted by the piston ring of the first invention or the second invention.

  In the case of a plurality of piston rings, the other piston rings used in combination with the piston rings of the first invention or the second invention are not particularly limited, and various piston rings currently known can be used. It can be selected appropriately.

  For example, in the case of the three ring configuration as described above, when the piston ring of the first invention or the second invention is used only as the first compression ring, for example, as the second compression ring, the outer peripheral sliding surface is Tapered shape, undercut shape, underhook shape, etc. are preferable, and the abutment shape is preferably an interrupted undercut shape, and the oil control ring is composed of a two-piece oil control ring consisting of a coil expander and an oil control ring body. A three-piece oil control ring consisting of two side rails and a spacer expander can be used. In particular, the outer peripheral sliding surface of the two-piece oil control ring has a straight shape, a double bevel shape, a barrel shape, and an oil control ring. It is preferable that only the upper surface side of the upper rail and the lower surface side of the lower rail have a barrel shape, and when combined with the first compression ring as the piston ring according to the present invention, a significant LOC reduction effect can be obtained. I can expect.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

(Experiment 1)
The piston ring and cylinder liner were processed by the following method, and the reciprocating frictional force between the piston ring and the cylinder liner was measured.

<Example ring>
The sliding face shape is a barrel face, the axial length (h1) is 1.2 mm, the radial length (a1) is 3.2 mm for the test piston ring (first compression ring), and the groove length is 50 μm. Groove depth: 50 μm, groove interval: 2 mm, and axial grooves were alternately formed from the upper side and the lower side as shown in FIG. The groove processing was performed using a laser marking device.

<Ring for comparison>
On the other hand, for comparison, a test piston ring similar to the above was prepared separately and used as it was without groove processing. ,

<Multi uneven cylinder liner>
A concave portion was formed by a blasting machine using a masking plate in the center area of the stroke of a cylinder liner (material: FC250) having the dimensions (mm) shown in FIG. The concave portion has a diamond shape. After the recess was formed, honing was performed on the inner wall surface of the cylinder liner 190. In the honing process, burrs may be generated at the end of the formed recess, and this is to be deleted. The shape of the formed recess was a rhombus, and both the average length in the axial direction and the average length in the circumferential direction were 1.4 mm. Further, the average length of the concave portions in the cylinder radial direction was 10 μm, and the area ratio of the concave portions in FIG. 14 was 50%.

<Comparison cylinder liner>
On the other hand, for comparison, a cylinder liner similar to the above was separately prepared and used as it was without performing the recess formation process.

<Measurement of reciprocating friction force>
The example ring and the comparative example ring prepared as described above, the multi-concave cylinder liner and the comparative cylinder liner were respectively combined, and the mechanical loss (FMEP) due to the frictional force was obtained using the apparatus shown in FIG. In this test method, a test piece piston ring was set on the piston, and after a familiar operation, the rotational speed corresponding to the engine speed was changed at an oil temperature of 80 ° C., and the frictional force was measured. At this time, the tangential tension Ft of the piston ring was 9.8 N. Moreover, the number of rotations at the time of measuring the reciprocating frictional force was 750 rpm, and the supply oil with SAE viscosity of 10W-30 was used.

<Evaluation>
The measurement result of mechanical loss is shown in FIG. FIG. 16 shows mechanical loss ratios in other combinations when the mechanical loss of the comparative example in which the comparative piston ring and the comparative cylinder liner are combined is 1.00.

  From FIG. 16, even when a multi-concave cylinder liner was used, when the comparative piston ring (conventional first compression ring) was combined (reference example), the mechanical loss was almost the same as that of the comparative example. On the other hand, when the multi-concave cylinder liner and the embodiment piston ring according to the present invention (first invention) were combined, it was confirmed that the mechanical loss of about 10% was reduced only by the first compression ring. did it.

  In addition, the piston ring having the configuration according to the second invention is combined with the multi-concave cylinder liner, so that the combination of the piston ring according to the first invention and the multi-concave cylinder liner is approximately 8 to 9%. It was confirmed separately that the mechanical loss was reduced.

  As is clear from these results, the friction force reduction effect of the multi-concave cylinder liner is extremely low for the first compression ring with a large contact width, but by combining it with the grooved piston ring according to the present invention. It can be seen that the effect of reducing the frictional force by the multi-concave cylinder liner is effectively exhibited.

DESCRIPTION OF SYMBOLS 1 ... Piston ring 2 ... Outer peripheral sliding surface 4, 5 ... Groove 6 ... Concave part in the inner wall surface of a cylinder or a cylinder liner

Claims (11)

The piston ring has a groove extending from one end part of the outer peripheral sliding surface of the piston ring in the ring axial direction of the sliding surface to the other end part in the surface of the sliding surface. A plurality of piston rings spaced apart from each other in the circumferential direction of the outer peripheral sliding surface;
A cylinder or a combination of cylinder liners in which a large number of recesses are formed on the inner wall surface of the cylinder or cylinder liner. The groove in the piston ring has a length (Ls _y ) in the axial direction of the piston ring of the groove, h1 represents the axial length of the piston ring, and each recess provided on the inner wall surface of the cylinder or cylinder liner. when the length in the axial direction of the cylinder or cylinder liner and Ld _y, piston ring and cylinder or a combination of the cylinder liner according to claim 1 satisfies the following relationship.
Ls _y ≦ h1-Ld _y (1)   The groove is provided with a plurality of grooves spaced apart from each other in the circumferential direction of the outer peripheral sliding surface of the piston ring, and one end of the outer peripheral sliding surface of the piston ring that cuts out one outer peripheral line in the ring axial direction. The groove which has a part and the groove which has an end part which notches the other end part outer periphery line in the ring axial direction of the outer periphery sliding surface of a piston ring are arrange | positioned from both. Combination of the described piston ring and cylinder or cylinder liner. The groove is provided with a plurality of grooves spaced apart from each other in the circumferential direction of the outer peripheral sliding surface of the piston ring, and one end of the outer peripheral sliding surface of the piston ring that cuts out one outer peripheral line in the ring axial direction A groove having a first portion (first opening end groove) and a groove having a first end portion that cuts off the outer peripheral line of the other end in the ring axial direction of the outer peripheral sliding surface of the piston ring (second opening end groove). In the case where the first opening end groove and the second opening end groove are adjacent to each other, the circumferential gap distance (Ds _x ) between the adjacent first opening end groove and the second opening end groove is a cylinder of each recess provided on the inner wall surface of the cylinder or cylinder liner. The combination of the piston ring and the cylinder or the cylinder liner according to any one of claims 1 to 3, wherein the following relational expression is satisfied, where Ld _x is a length in the circumferential direction of the cylinder liner.
Ld _x <Ds _x (2) The groove is provided with a plurality of grooves spaced apart from each other in the circumferential direction of the outer peripheral sliding surface of the piston ring, and one end of the outer peripheral sliding surface of the piston ring that cuts out one outer peripheral line in the ring axial direction A groove having a first portion (first opening end groove) and a groove having a first end portion that cuts off the outer peripheral line of the other end in the ring axial direction of the outer peripheral sliding surface of the piston ring (second opening end groove). In the case where the first opening end groove and the second opening end groove are adjacent to each other, the circumferential gap distance (Ds _x ) between the adjacent first opening end groove and the second opening end groove is a cylinder of each recess provided on the inner wall surface of the cylinder or cylinder liner. Alternatively, the length of the cylinder liner in the circumferential direction is Ld _x , and the total width of the two recesses adjacent in the circumferential direction at the same height position in the axial direction of the cylinder or cylinder liner (including the gap distance between the two recesses) That.) When the Lwd _x a piston ring and a cylinder or a combination of a cylinder liner according to claim 1 satisfies the following relationship.
Ld _x <Ds _x <Lwd _x (3) The outer peripheral sliding surface of the piston ring is extended along the circumferential direction of the ring from one end of the circumferential edge of the ring facing the ring mating edge, and the other facing the ring mating ring The outer periphery of the piston ring slides in a groove having a width of 1.0 mm or less and a depth of 0.001 to 0.2 mm leading to the other end in the sliding surface, in which the outer edge line of the circumferential end is notched. A plurality of piston rings spaced apart from each other in the axial direction of the surface;
A cylinder or a combination of cylinder liners in which a large number of recesses are formed on the inner wall surface of the cylinder or cylinder liner. At least one of the plurality of convex portions formed by being surrounded by the outer peripheral line of the outer peripheral sliding surface of the piston ring and the edge line of the groove is the length (Lb) of the convex portion in the axial direction of the piston ring. 7. The structure according to claim 6, wherein _y ) satisfies the following relational expression, where Ld _y is the length in the axial direction of the cylinder or cylinder liner of each recess provided on the inner wall surface of the cylinder or cylinder liner. Combination of piston ring and cylinder or cylinder liner.
Lb _y > Ld _y (4)   The combination of a piston ring and a cylinder or a cylinder liner according to any one of claims 1 to 7, wherein the piston ring is a compression ring.   The combination of a piston ring and a cylinder or a cylinder liner according to any one of claims 1 to 7, wherein the piston ring is a first compression ring.   The cylinder or cylinder liner has at least an upper surface position of the ring groove of the uppermost piston ring at the bottom dead center of the piston from a lower surface position of the ring groove of the lowest piston ring at the top dead center of the piston on the inner wall surface thereof. A piston ring and a cylinder according to any one of claims 1 to 9, wherein the piston ring is a cylinder or a cylinder liner in which a number of recesses are formed in a central region of a stroke that is a region between the piston ring and the cylinder. Or a combination of cylinder liners.   The piston ring used for the combination of the piston ring in any one of Claims 1-10, and a cylinder or a cylinder liner.

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