JP2005090442A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine capable of enhancing superior seizure resistance, superior low friction performance, and low fuel consumption in response to a difference in an operation state. <P>SOLUTION: This engine has a cylinder liner 16 having a space part for reciprocating a piston, a first part composed of a thrust part 16S and an anti-thrust part 16AS among an inner surface of the cylinder liner opposed to the piston, second parts (161 to 164) having surface roughness larger than surface roughness of the first part, and composed of a part except for the thrust part and the anti-thrust part among the inner surface, and inclined grooves (161G to 164G) formed in the second part, and obliquely crossing a boundary line of the first part and the second parts by extending toward the bottom dead center side from the top dead center side of the piston. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention belongs to the technical field of engines.

  Conventionally, the inner surface of a cylinder liner constituting an engine is not a completely smooth surface but has a surface property having a moderately large surface roughness. Such a surface property can be obtained as a result of honing the inner surface, for example. Thereby, it becomes possible to hold | maintain lubricating oil to the unevenness | corrugation of an unevenness | corrugation, and can improve seizure resistance. In addition to the improvement in the seizure resistance described above, a configuration is also known which aims at effects such as low friction and fuel consumption reduction by providing a difference in the degree of roughness with respect to the inner surface of the cylinder liner. As such, for example, as disclosed in Patent Document 1, the surface roughness of the thrust / anti-thrust portion on which the piston acts is relatively rough, and the surface of the portion other than the thrust / anti-thrust portion A configuration in which the roughness is formed relatively finely is known.

JP 7-91311 A

  However, the conventional engine has the following problems. That is, the possibility that seizure occurs between the piston and the inner surface of the cylinder liner, or the degree of friction that occurs between them, may vary depending on the difference in operating conditions of the engine including the piston and the like. For example, when the engine is mounted on a vehicle, when the vehicle is traveling at a relatively high speed such as traveling on a highway, the lubricating oil between the piston and the cylinder liner tends to be insufficient. Better anti-seizure performance is required than excellent low friction. Therefore, from this viewpoint, the surface roughness of the inner surface of the cylinder liner is preferably relatively large. On the other hand, when the vehicle is traveling at a relatively low speed such as in an urban area, there is sufficient lubricating oil between the piston and the cylinder liner, so that the low friction performance is excellent. Is required. Therefore, from this viewpoint, it is preferable that the surface roughness of the inner surface of the cylinder liner is relatively small. In particular, in this case (in the case of urban driving), the surface roughness of the inner surface of the conventional piston liner is too large, and the friction loss between the sliding portion between the inner surface and the piston skirt tends to be large. There was a problem of causing deterioration.

  As described above, although the relationship between the cylinder liner and the piston is different according to the difference in operating conditions, no special consideration has been given to this point in the past. Even in the above-mentioned Patent Document 1, there is no particular reference to this point, and only a difference is provided in the surface roughness between the thrust / anti-thrust portion and the other portions, and measures according to the operating conditions are particularly taken. I don't mean.

  The present invention has been made in view of the above problems, and provides an engine capable of realizing excellent seizure resistance, excellent low friction performance, and low fuel consumption according to the difference in operating conditions. Let it be an issue.

[1]
In order to solve the above problems, an engine of the present invention comprises a piston, a cylinder liner having a space in which the piston reciprocates, and a thrust portion and an anti-thrust portion among the inner surfaces of the cylinder liner facing the piston. A first portion; a second portion having a surface roughness greater than the surface roughness of the first portion; the second portion including a portion other than the thrust portion and the anti-thrust portion of the inner surface; and the second portion. , An inclined groove extending from the top dead center side of the piston toward the bottom dead center side and obliquely intersecting a boundary line of the first part and the second part, and lubrication for supplying lubricating oil to the space part Oil supply means.

  According to the engine of the present invention, the inner surface of the cylinder liner includes a first portion and a second portion, and the first portion further includes a thrust portion and an anti-thrust portion. Here, the thrust part and the anti-thrust part are the parts where the most force acts between the piston and the inner surface of the cylinder liner, and typically the piston that supports the connecting rod on the inner surface of the cylinder liner. It is located in the part in general along the axis line which penetrates the connection hole which is a part (in other words, the part where the said inner surface and the said axis line do not cross). The first portion has a smaller surface roughness than the second portion.

  According to the engine of the present invention having such a configuration, it is possible to realize excellent seizure resistance, and excellent low friction and low fuel consumption depending on the difference in operating conditions. More specifically, it is as follows.

  First, when the engine is rotating at high speed, the lubricating oil supplied from the lubricating oil supply means to the inside (space part) of the cylinder liner tends to be insufficient, and seizure occurs between the piston and the cylinder liner. The risk of causing it increases. However, in the present invention, this problem can be solved by forming the inclined groove in the second portion. This is because, firstly, the lubricating oil stays in the inclined groove, so that there is no shortage of lubricating oil as described above between the second portion, which is the formation site of the inclined groove, and the piston. The lubricity between the two can be maintained well. Further, the inclined groove according to the present invention is formed so as to extend from the top dead center side of the piston toward the bottom dead center side and obliquely intersect the boundary line of the first part and the second part. Therefore, the lubricating oil staying in the inclined groove can flow into the first portion. In this case, the force causing the inflow is mainly a negative pressure generated in the space portion of the cylinder liner when the piston moves from the top dead center toward the bottom dead center. Further, if the top dead center and the bottom dead center are arranged substantially in the vertical direction, gravity can be added to the cause of the inflow. In any case, the lubricating oil flows in and the lubricating oil is sufficiently present in the first portion. Therefore, the lack of lubricating oil as described above does not occur between the first portion and the piston, and therefore the lubricity between the two can be maintained well. As a result, excellent lubricity can be enjoyed even when the engine is rotating at high speed.

  Second, when the engine is rotating at a low speed, good low friction performance can be enjoyed between the piston and the cylinder liner. This is because the thrust portion and the anti-thrust portion, which are portions where the piston exerts the most force on the cylinder liner, have a smaller surface roughness as described above. Incidentally, when the engine is rotating at a low speed, there is sufficient lubricating oil, so there is no particular problem with lubricity.

  And especially in this invention, there exist the following characteristics regarding the inflow of the said lubricating oil. That is, the flow of lubricating oil from the inclined groove of the second part into the first part occurs not only when the engine is rotating at a high speed as described above, but also when the engine is rotating at a low speed. However, the present invention is characterized in that there is a difference in the degree of inflow, more specifically, the amount of lubricating oil flowing in, when the engine is rotating at a high speed and when the engine is rotating at a low speed. . That is, when the engine is rotating at a high speed, the piston moves very quickly from top dead center to bottom dead center, so the negative pressure becomes larger, so the amount of lubricating oil flowing in increases, but the low speed In the case of rotation, the negative pressure becomes smaller as opposed to the above, and the supply amount of the lubricating oil becomes smaller. This is because a higher lubricity is desired in the thrust portion and the anti-thrust portion when the engine is rotating at a high speed, and a higher low friction property is desired in both portions when the engine is rotating at a low speed. You can see that they match well.

  The “inclined groove” referred to in the present invention includes a group of a plurality of parallel grooves and another group of a plurality of parallel grooves intersecting therewith, so-called cross-hatched grooves.

[2]
In one aspect of the engine of the present invention, there are a plurality of the inclined grooves, and the plurality of inclined grooves do not intersect each other.

  According to this aspect, since each of the plurality of inclined grooves is formed so as not to intersect, the cross-hatching groove or other groove where the intersection of the grooves exists (hereinafter referred to as “cross-hatching-like groove”). Compared with the case where is formed, the supply of the lubricating oil is performed more smoothly and more rapidly. This is because, in the cross-hatching-like groove, there is a high possibility that the lubricating oil stays at the intersection of the grooves, but in this embodiment, such a problem does not occur.

[3]
In another aspect of the engine of the present invention, the second portion includes a first thrust facing portion and a second thrust facing portion sandwiching the thrust portion, on a boundary line between the first thrust facing portion and the thrust portion, The first thrust concavity and convexity row that appears based on the inclined groove formed in the first thrust facing portion and the boundary line between the second thrust facing portion and the thrust portion are formed in the second thrust facing portion. The second thrust portion unevenness rows appearing on the basis of the inclined grooves are such that the convex and concave positions constituting each are shifted from each other between the first thrust portion unevenness rows and the second thrust portion unevenness rows.

  According to this aspect, for example, the protrusions constituting the second thrust portion unevenness row correspond to the recesses forming the first thrust portion unevenness row, and the latter recesses correspond to the former protrusion. In other words, the cylinder liner is configured as if both the concavo-convex rows are arranged alternately with the thrust portion interposed therebetween. According to this, the negative pressure generated when the piston moves from the top dead center side to the bottom dead center side is the depression of the first thrust portion unevenness row, then the second thrust portion unevenness row, and further In this way, the first thrust portion concave / convex rows of concave and convex portions act in sequence on the concave portions of the concave and convex rows. On the other hand, when the recesses in the second thrust portion unevenness row correspond to the recesses in the first thrust portion unevenness row, the negative pressure is applied to these two recesses at the same time. As a result of the distribution of the drawing force, the amount of lubricating oil led to the thrust portion may be relatively reduced. In this respect, in this aspect, as a result of the negative pressure acting entirely on the respective recesses of the first thrust portion unevenness row and the second thrust portion unevenness row as described above, the amount of the lubricating oil as described above is reduced. No decrease occurs, and as a result, the amount of lubricating oil supplied to the thrust portion can be relatively increased. Further, according to this aspect, since the concave portions of the first thrust portion unevenness row and the second thrust portion unevenness row are arranged alternately, the lubricant is uniformly supplied onto the surface of the thrust portion. be able to.

  In this aspect, the reference is made only in relation to the “thrust portion”, but it goes without saying that the same argument as described above is valid in relation to the “anti-thrust portion”. That is, regarding the configuration requirements of this aspect, the configuration in which the reading as shown in Table 1 below is implemented is also within the scope of the present invention. In addition, it goes without saying that an aspect having both the configuration requirements of the present embodiment and the configuration requirements read in Table 1 below is also within the scope of the present invention.

[4]
In another aspect of the engine of the present invention, the second portion includes a first thrust facing portion and a second thrust facing portion that sandwich the thrust portion, and a first anti-thrust facing portion and a second anti-thrust portion that sandwich the anti-thrust portion. The number of the inclined grooves formed in the first thrust facing portion and the second thrust facing portion is formed in the first anti-thrust facing portion and the second anti-thrust facing portion. More than the number of the inclined grooves.

  According to this aspect, in general, the thrust portion to which a larger load or force is applied than the anti-thrust portion is supplied with more lubricating oil than the anti-thrust portion. Therefore, according to this aspect, it is possible to achieve higher lubricity in the thrust portion where wear is more likely to occur than in the anti-thrust portion. This also makes it possible to equalize the degree of wear between the thrust portion and the anti-thrust portion, which greatly contributes to extending the overall life of the engine and improving reliability.

[5]
In another aspect of the engine of the present invention, the inclined groove includes a parallel portion parallel to a direction perpendicular to the axis of the piston.

  According to this aspect, due to the presence of the parallel portion, the holding force of the lubricating oil in the inclined groove is increased. Here, “strong” holding force specifically means that, for example, the amount of lubricating oil retained is relatively large, or the lubricating oil can be retained for a relatively longer time. As a result, for example, it is possible to prevent a situation in which the supply amount of the lubricating oil flowing into the thrust portion and the anti-thrust portion fluctuates extremely as the degree of reciprocation (for example, speed) of the piston changes. it can. Therefore, the engine can be operated more stably. Also, for the same reason (strong holding force), there is no possibility that the lubricating oil will be completely removed from the inclined groove when the engine is stopped. Therefore, when the engine is started, there is wear between the inner surfaces of the piston and the cylinder liner. Generation | occurrence | production can be prevented and the starting torque requested | required at the time of the said start can also be restrained small.

[6]
In another aspect of the engine of the present invention, a recess is formed in the first portion.

  According to this aspect, the lubricating oil supplied from the inclined groove to the thrust portion and the anti-thrust portion is held more strongly in the thrust portion and the anti-thrust portion. Can be improved.

  Note that the fact that the lubricating oil in the above is held “stronger” or the holding power of the lubricating oil is “strong” is synonymous with that already described.

[7]
In this aspect, the concave portion may be formed in a portion corresponding to the top dead center of the piston on the inner surface of the cylinder liner.

  According to such a structure, the said recessed part is formed in the part corresponding to the top dead center of the said piston which is easy to produce solid oily state between evaporation of lubricating oil and an inner surface of a piston and a cylinder liner. Therefore, good lubricity between the thrust portion and the anti-thrust portion and the piston can be realized in a place where higher lubricity is desired.

  Note that the “concave portion” referred to in the present configuration can be configured to include, for example, “including an extended groove obtained by extending the inclined groove to the thrust portion and the anti-thrust portion”.

[8]
In another aspect of the engine of the present invention, the depth of the inclined groove formed in a portion of the inner surface of the cylinder liner corresponding to the top dead center of the piston is the same as that of the inclined groove formed in the other portion. Deeper than depth.

  According to this aspect, the depth of the inclined groove formed in the portion corresponding to the top dead center of the piston, which is likely to cause a solid lubrication state between the inner surfaces of the piston and the cylinder liner, is increased. This means that the amount of lubricating oil retained in the part is relatively large. Therefore, in this portion, it is possible to prevent a solid lubrication state or a state close to this from appearing between the inner surface of the cylinder liner and the piston. In addition, this makes it possible to prevent a situation in which the degree of wear differs between the portion corresponding to the top dead center of the piston and other portions.

  In addition, in this aspect, it is preferable to employ the following configurations. That is, first, “the depth D1 of the inclined groove formed in the portion corresponding to the top dead center of the piston on the inner surface of the cylinder liner, formed in the portion corresponding to the bottom dead center of the piston. The depth D2 of the inclined grooves and the depth D3 of the inclined grooves formed in other portions satisfy the relationship D1 <D2 ≦ D3 ”(hereinafter referred to as“ first configuration ”). Adopt it. According to this, since the relationship between the depths D1, D2, and D3 is determined in the order in which wear is likely to occur, the above-described operational effects can be enjoyed more reliably.

  Alternatively, secondly, in addition to the first configuration, a configuration in which “the value gradually increases from the depth D3 to at least one of the depth D1 and the depth D2” may be employed. . According to this, since the lubricating oil is held according to the speed of the reciprocating motion of the piston, the above-described effects can be enjoyed more effectively.

[9]
In another aspect of the engine of the present invention, the sides constituting the cross-sectional shape of the inclined groove are directed from the surface of the second portion toward the axis of the piston and perpendicular to the axis or at the top dead center of the piston. A first side extending toward the first side, and a second side extending from one end of the first side or a point in the vicinity thereof toward the surface and extending from the top dead center side toward the bottom dead center side Including.

  According to this aspect, first, since the first side constituting the cross-sectional shape of the inclined grooves extends perpendicularly to the axis of the piston or toward the top dead center side of the piston, It is difficult for the lubricating oil contained therein to enter the combustion chamber located above the piston. Therefore, since the amount of lubricating oil sent to the exhaust pipe can be relatively reduced, the emission can be improved. On the other hand, since the second side constituting the cross-sectional shape of the inclined groove extends from the top dead center side of the piston toward the bottom dead center side, the lubricating oil in the inclined groove is scraped out. It is easy to be done. Therefore, since the supply amount of the original lubricating oil to be introduced into the cylinder liner (in other words, the lubricating oil amount to be provided in the lubricating oil supply means) may be reduced, the consumption amount of the lubricating oil As a result, it is possible to reduce the cost of the engine, for example, by omitting the installation of an oil jet.

  As described above, according to the present invention, excellent seizure resistance (that is, high lubricity) can be achieved when the engine is rotating at high speed, and excellent low resistance can be achieved when rotating at low speed. Various performances required in accordance with the operating state of the engine can be better realized such that frictional properties (and hence low fuel consumption) can be realized.

  Such operations, effects and other advantages of the present invention will become apparent from the embodiments described below.

(First embodiment)
Below, the 1st Embodiment of this invention is described, referring FIG. FIG. 1 is a schematic configuration diagram of the power output apparatus according to the first embodiment.

  First, with reference to FIG. 1, the structure around the engine 150, especially the piston 18 will be described. As shown in FIG. 1, the engine 150 includes a cylinder block 14. A cylinder liner 16 that forms the inner periphery of the cylinder block 14 is disposed. The engine 150 includes a plurality of cylinders. For convenience of explanation, FIG. 1 shows one cylinder among the plurality of cylinders. A piston 18 is disposed inside the cylinder liner 16. The piston 18 can slide in the vertical direction in FIG. 1 inside the cylinder liner 16. The piston 18 is provided with a compression ring 181 and an oil ring 182. The piston 18 is connected to a crankshaft (not shown) via a connecting rod 189, and a flywheel FW is connected to the crankshaft. A ring gear FW1 is provided on the outer periphery of the flywheel FW. The ring gear FW1 meshes with a pinion gear SM1 attached to a starter motor (electric motor) SM. At the normal start or cold start of the engine 150, the power generated by the rotation of the starter motor SM is transmitted to the flywheel FW and the crankshaft via the pinion gear SM1 and the ring gear FW1. Thus, the engine 150 is cranked.

  A combustion chamber 20 is formed above the piston 18 inside the cylinder liner 16. The tip of the spark plug 26 is exposed in the combustion chamber 20. The spark plug 26 ignites the fuel in the combustion chamber 20 by receiving an ignition signal from an ECU (Engine Control Unit) (not shown) or the like. An intake manifold 34 communicates with the combustion chamber 20 via an intake valve 32, and an exhaust manifold 30 communicates with an exhaust valve 28.

  In the engine 150 having such a configuration, in the first embodiment, the inner surface 16N of the cylinder liner 16 is configured as follows. Hereinafter, the configuration of the inner surface 16N of the cylinder liner will be described with reference to FIGS. FIG. 2 is a perspective view illustrating only the piston 18 and the cylinder liner 16 extracted, and FIG. 3 is a developed view showing the inner surface of the cylinder liner 16 as a table.

  As shown in FIGS. 2 and 3, the cylinder liner 16 is roughly composed of two parts. First, one of them is a portion composed of a thrust portion 16S and an anti-thrust portion 16AS. The thrust portion 16S and the anti-thrust portion 16AS can be defined as portions facing the piston skirt portion 183 that forms part of the piston 18 (see also FIG. 1). The outer surface of the piston skirt 183 is formed so as to be along an axis passing through a connection hole 184 that pivotally supports the connecting rod 189 (in other words, the outer surface is formed so as not to intersect the axis). ing.). From this, when the piston 18 moves up and down in the figure, the piston skirt portion 183 has a portion where the most force acts between the piston 18 and the inner surface 16N of the cylinder liner 16 (hereinafter referred to as the force). It can be seen that the pressure generated between the two is sometimes referred to as “skirt pressure”. The piston skirt portion 183 is provided to receive the force. Although the three-dimensional shape of the piston 18 including the piston skirt portion 183 is strictly more complicated, the description thereof is omitted here (refer to FIG. 6 and the description thereof).

  On the other hand, the other part is a part other than the part composed of the thrust part 16S and the anti-thrust part 16AS (see reference numerals 161 to 164 in FIGS. 2 and 3). This part is further divided into four parts. That is, the thrust portion left facing portion 164 and the thrust portion right facing portion 161 that exist on the left and right in the figure with the thrust portion 16S in the middle, and the anti-thrust portion left facing on the left and right with the antithrust portion 16AS in the middle. Part 162 and anti-thrust part right facing part 163 (note that the term “left” or “right” is merely a convenient name based on FIG. 3).

  Of the above-mentioned parts, first, the anti-thrust part left facing part 162 and the anti-thrust part right facing part 163 are respectively inclined grooves 162G extending from the upper left to the lower right in the drawing, as shown in FIG. A plurality of inclined grooves 163G extending from the upper right to the lower left in the figure are formed. Accordingly, the inclined grooves 162G and 163G are inclined with respect to the boundary line B1 of the anti-thrust portion left facing portion 162 and the anti-thrust portion 16AS and the boundary line B2 of the anti-thrust portion right facing portion 163 and the anti-thrust portion 16AS, respectively. Will intersect. The term “oblique” as used herein means that the inclined grooves 162G and 163G are formed so as to extend in the above-described direction, so that both of them are directed toward the boundary lines B1 and B2 from above in the drawing. It intersects as going down. On the other hand, inclined grooves 161G and 164G are formed in the thrust portion right facing portion 161 and the thrust portion left facing portion 164 in the same manner as described above. As is apparent from FIG. 3, these inclined grooves 161 and 164G are also directed to the thrust portion right facing portion 161 and the boundary lines B3 and B4 between the thrust portion left facing portion 164 and the thrust portion 16S and from the upper side to the lower side in the figure. To cross each other. In contrast, the thrust portion 16S and the anti-thrust portion 16AS facing the piston skirt portion 183 are not formed with the inclined grooves 161G to 164G, and have a smooth surface property.

  As described above, the inner surface 16N of the cylinder liner 16 in the first embodiment has a smooth surface (and therefore a smaller surface roughness), the thrust portion 16S and the anti-thrust portion 16AS, and the inclined grooves 161G to 164G. (Therefore, the surface roughness is greater) and the other portions 161 to 164. In the present embodiment, in particular, the inclined grooves 161G to 164G are formed so as not to cross each other as shown in FIG. 3, but the present invention is not limited to this form and has been widely observed in the past. A cross-hatched groove as described above may be formed.

  When the inner surface 16N of the cylinder liner 16 has the above-described configuration, the following operational effects can be obtained in the engine of the first embodiment. First, when the engine 150 is in an operating state, that is, when the piston 18 is moving in the vertical direction of FIG. 1 or FIG. 2, piston jet and crank journal lubricating oil (not shown) are moved upward in the figure of the cylinder liner 16. It is ejected toward. Then, the lubricating oil stays in the inclined grooves 161G to 164G.

  Here, for example, when the engine 150 is mounted on an automobile, the lubricating oil between the piston 18 and the cylinder liner 16 is generally insufficient when the automobile is traveling at a relatively high speed such as traveling on a highway. Tend to. Therefore, in this case, there is a concern that burn-in occurs between the two. However, in the first embodiment, occurrence of such a problem can be prevented in advance.

  First, the lubricating oil stays in the inclined grooves 161G to 164G as described above. Therefore, the thrust portion right facing portion 161 and the thrust portion left facing portion 164 of the inner surface 16N of the cylinder liner 16 are provided. This is because good lubricity is maintained between the anti-thrust portion left facing portion 162 and the anti-thrust portion right facing portion 163 and the piston 18. Second, as described above, the inclined grooves 161G to 164G are formed so as to cross from the upper side to the lower side in the figure toward the boundary lines B1 to B4, so that the inclined grooves 161G to 164G Since the lubricating oil is supplied to the thrust portion 16S and the anti-thrust portion 16AS in the inner surface 16N of the cylinder liner 16 relatively abundantly (see the arrows in FIG. 3), the thrust portion 16S and the anti-thrust portion 16AS and the piston 18 are supplied. This is because good lubricity can be maintained even between the two. Incidentally, the supply of such lubricating oil is possible not only due to the action of gravity but also because negative pressure is generated inside the cylinder liner 16 when the piston 18 moves downward in the figure. In addition, since the inclined grooves 161G to 164G according to the present embodiment are formed so as not to intersect each other as described above, compared to a case where there is an intersection between grooves like a cross-hatched groove. Thus, the supply of the lubricating oil is performed more smoothly and more quickly (in a cross-hatched groove, there is a high possibility that the lubricating oil will stay at the intersection of the grooves).

  On the other hand, when the vehicle is traveling at a relatively low speed such as traveling in an urban area, good low friction performance can be enjoyed between the piston 18 and the cylinder liner 16. This is because the thrust portion 16S and the anti-thrust portion 16AS, which are portions where the piston 18 exerts the most force on the cylinder liner 16, have smooth surface properties as described above. Incidentally, when the engine 150 is rotating at a low speed, there is a sufficient amount of lubricating oil, so that there is no particular problem with lubricity. However, as described above with respect to the high-speed rotation, even in this case, the lubricating oil in the inclined grooves 161G to 164G is still supplied to the thrust portion 16S and the anti-thrust portion 16AS. It can be considered that the lubricity is improved to some extent by the presence of the inclined grooves 161G to 164G.

  Here, particularly in the present embodiment, there is a difference in the amount of lubricating oil supplied to the thrust portion 16S and the anti-thrust portion 16AS when the engine 150 rotates at a high speed and when the engine 150 rotates at a low speed. Has major features. In other words, when the engine 150 is rotating at a high speed, the piston 16 moves very rapidly downward in the figure, so that the negative pressure is increased, so that the amount of lubricating oil supplied is increased, but the piston 16 is rotated at a low speed. In contrast, the negative pressure is smaller than the above, and the supply amount of lubricating oil is smaller. This means that when the engine 150 is rotating at a high speed, higher lubricity is desired in the thrust portion 16S and the anti-thrust portion 16AS, and when the engine 150 is rotating at a lower speed, higher friction is desired in the portions 16S and 16AS. It can be seen that the request is well met.

  As described above, in the first embodiment, when the engine 150 is rotating at a high speed, excellent seizure resistance (that is, high lubricity) can be realized, and when the engine 150 is rotating at a low speed, it is excellent. Various performances required in accordance with the operating condition of the engine 150 can be better realized such that low friction (and consequently low fuel consumption) can be realized. In addition, as described above, better seizure resistance, high lubricity, low friction, and low fuel consumption can be realized according to time, which further reduces noise generated between the piston 18 and the cylinder liner 16. This also brings about an effect of improving the reliability of the engine 150.

  Further, in this regard, in the first embodiment, excellent low friction is realized when the engine 150 is rotating at a low speed, so that the startability of the engine 150 can be well maintained or improved. (Ie, engine 150 can be started with lower energy). This also makes it possible to reduce the capacity of the starter motor SM and the capacity of a battery (not shown) that supplies power to the starter motor SM.

  Furthermore, in the first embodiment, the thrust portion 16S and the anti-thrust portion 16AS are not formed with the inclined grooves 161G to 164G, and the thrust portion right facing portion 161 and the thrust portion left facing are formed with the inclined grooves 161G to 164G. In the portion 164, the anti-thrust portion left facing portion 162, and the anti-thrust portion right facing portion 163, the lubricating oil staying in the inclined grooves 161G to 164G flows into the thrust portion 16S and the anti-thrust portion 16AS. Therefore, it can be said that the lubricating oil hardly remains above the cylinder liner 16 in the figure. Thereby, reduction of lubricating oil consumption and improvement of emission can be aimed at. This is due to the following circumstances. That is, in a situation where the lubricating oil remains in the upper portion of the cylinder liner 16 in the drawing, when the piston 18 descends, the lubricating oil burns in the combustion chamber 20 and the series of spaces, so that the consumption amount of the lubricating oil is reduced. Increased and burned or unburned lubricating oil is mixed in the exhaust gas, resulting in worse emission. In fact, in a cylinder liner having a cross-hatching groove, which is a conventional general configuration, the lubricating oil is scraped by a piston ring (the cross-hatching groove, especially the lubricating oil staying at the intersection of the grooves). Is not performed sufficiently, and the above-mentioned problems tend to occur. However, in the first embodiment, as described above, the situation in which the lubricating oil remains in the upper portion of the cylinder liner 16 in the drawing is less likely to occur, so that the above-described problems do not have to be suffered.

  In addition, the specific formation aspect of the inclined groove | channel 161G thru | or 164G which concerns on 1st Embodiment can be defined based on the Stribeck diagram shown qualitatively, for example in FIG. Here, the Stribeck diagram is a characteristic diagram showing how the friction coefficient changes in accordance with the change in the negative pressure characteristic. Here, the negative pressure characteristic is obtained by multiplying the viscosity μ of the lubricating oil by the speed U between the contacted objects and dividing by the load W applied between them (the horizontal axis in FIG. 4). Since it is friction between the inner surface 16N of the cylinder liner 16 and the piston 18 that has been attracting attention consistently in the present embodiment, it is considered that a change occurs mainly in the U and W in FIG. Of course, the viscosity μ of the lubricating oil is also greatly related to changes with temperature. For example, the faster the engine 150 rotates, the more fluid lubrication (see the right side in FIG. 4) enters, and the slower the engine 150 enters the individual lubrication area (see the left side in FIG. 4). Further, from this figure, for example, it is possible to indirectly determine the amount of lubricating oil to be supplied to the thrust portion 16S and the anti-thrust portion 16AS.

  In consideration of the above, based on FIG. 4, the formation mode of the inclined grooves 161G to 164G, more specifically, for example, the number or formation density, the inclined grooves 161G to 164G and the boundary lines B1 to B4, It is possible to appropriately determine the angle, depth, etc. at which

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a view having the same concept as in FIG. 3, and shows a different formation mode of the inclined grooves. FIG. 6 is an explanatory view showing a more detailed shape of the piston skirt portion 183. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the second embodiment will be described. An explanation will be added. In addition, regarding the reference numerals used in the drawings referred to in the first embodiment, the same reference numerals are used in the drawings referred to in the second embodiment when the same objects are indicated.

  As shown in FIG. 5, the second embodiment is characterized by the intersections between the inclined grooves 161G to 164G and the boundary lines B1 to B4. That is, in FIG. 5, for example, on the line segment ZZ ′ vertically lowered from the intersection Z between the inclined groove 162 </ b> G formed in the anti-thrust left facing portion 162 and the boundary line B <b> 1 toward the boundary line B <b> 2, The intersections X1 and X2 between the inclined groove 163G formed in the part right facing part 163 and the boundary line B2 do not go (the point Z ′ does not coincide with the intersections X1 and X2). In other words, the inclined groove 162G and the inclined groove 163G are formed so as to be different from each other across the anti-thrust portion 16AS. More generally, the inclined groove 162G appears on the boundary line B1 based on the inclined groove 162G. The concave and convex rows and the concave and convex rows that appear on the boundary line B2 based on the inclined grooves 163G are such that the positions of the convex and concave constituting each of them are shifted from each other. This configuration is similarly applied to the thrust portion 16S.

  According to such a form, first, the amount of lubricating oil flowing into the thrust portion 16S and the anti-thrust portion 16AS from the inclined grooves 161G to 164G, for example, the point Z ′ and the intersection X1 or X2 coincide with each other. It can be relatively increased compared to the case. This is due to the following circumstances. That is, in the second embodiment, when the piston 18 moves downward in FIG. 5, the intersections of the inclined grooves 161G to 164G and the boundary lines B1 to B4 appear sequentially and alternately. For example, paying attention to the anti-thrust portion 16AS in FIG. 5, the intersection X1 is first, and then the intersection Z (the point Z is one of the intersections between the inclined groove 162G and the boundary line B1), and then. Intersection X2 seems to be. Here, if the point Z ′ coincides with the intersections X1 and X2, the piston 18 passes through the intersections Z and X1 or X2 at the same time. Therefore, in this case, since the negative pressure generated when the piston 18 passes through the portion is applied simultaneously at the intersections Z and X1 or X2, the force to draw out the lubricating oil is dispersed, and as a result, the anti-thrust portion The supply amount of the lubricating oil led to 16AS is relatively reduced. In this respect, in the second embodiment, the intersections appear sequentially and alternately as described above. For example, when the piston 18 passes through each of the intersections X1, Z, and X2, for example. The negative pressure that occurs in the whole will be applied from time to time. Therefore, the amount of lubricating oil guided to the anti-thrust portion 16AS can be relatively increased.

  As a result, according to the second embodiment, the lubricity between the thrust portion 16S and the anti-thrust portion 16AS and the piston skirt portion 183 can be further improved.

  Incidentally, this is also related to the specific shape of the piston 18. That is, the piston skirt portion 183 has a three-dimensional shape as shown in FIG. 2, but more specifically, for example, as conceptually shown in FIG. 6, a cross section perpendicular to the axial direction. In other words, it is shaped so as to have an elliptical shape, and to have a tapered shape from the top dead center side to the bottom dead center side. With such a shape, there is a difference in clearance (see reference numerals C1 to C4 in the drawing) between the inner surface 16N of the cylinder liner 16 and the piston skirt portion 183. Therefore, depending on which of the plurality of inclined grooves 161G to 164G is opposed to which part of the piston skirt 183, the negative pressure applied to the groove may differ. . Even in view of the above, if the inclined grooves 161G to 164G are formed in “steps” as described above, it is possible to preferably cope with the difference in the negative pressure applied as described above. Therefore, the relative amount of the lubricating oil guided to the thrust portion 16S and the anti-thrust portion 16AS can be increased.

  Moreover, according to 2nd Embodiment, the following effects can also be acquired 2ndly. That is, since the inclined grooves 162G and 163G (or the inclined grooves 161G and 164G) are formed in steps, a single line of lubricating oil flows from the inclined groove 162G into the anti-thrust portion 16AS in FIG. The oil flows in), and two lines of lubricating oil flow from the two inclined grooves 163G located between them (that is, the lubricating oil flows from the intersections X1 and X2). Lubricating oil is evenly supplied on the surfaces of 16S and anti-thrust portion 16AS. Also by this, the lubricity between the thrust portion 16S and the anti-thrust portion 16AS and the piston skirt portion 183 can be improved.

  As described above, according to the second embodiment, it is possible to achieve excellent lubricity between the piston skirt portion 183 and the thrust portion 16S and the anti-thrust portion 16AS as a whole. This is particularly effective when the uniform skirt pressure is high. In addition, as described above, a relatively large and efficient (ie, non-biased) supply of lubricating oil to the thrust portion 16S and the anti-thrust portion 16AS is realized, so that the lubricant is introduced into the cylinder liner 16. The supply amount of the main lubricant to be used may be reduced. Therefore, the consumption amount of the lubricating oil can be reduced, and thereby, the cost of the engine 150 can be reduced, for example, an oil jet can be omitted.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a view having the same concept as in FIG. 3 and shows a different aspect of forming the inclined grooves. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the third embodiment will be described. An explanation will be added. In addition, regarding the reference numerals used in the drawings referred to in the first embodiment, the same reference numerals are used in the drawings referred to in the third embodiment when the same objects are indicated.

  In the third embodiment, as shown in FIG. 7, the number of inclined grooves 161G and 164G formed in the thrust portion left facing portion 164 and the thrust portion right facing portion 161 sandwiching the thrust portion 16S is different from the anti-thrust portion 16AS. The number of the inclined grooves 162G and 163G formed in the anti-thrust portion left facing portion 162 and the anti-thrust portion right facing portion 163 existing on the left and right sides of the middle is larger than the number of the inclined grooves 162G and 163G.

  According to such a form, the thrust portion 16S to which a larger load or skirt surface pressure is applied than the anti-thrust portion 16AS is supplied with more lubricating oil than the anti-thrust portion 16AS. Therefore, according to the third embodiment, the thrust portion 16S that is more likely to be worn can achieve higher lubricity than the anti-thrust portion 16AS. This also makes it possible to equalize the degree of wear between the thrust portion 16S and the anti-thrust portion 16AS, which greatly contributes to extending the overall life of the engine 150 and improving reliability.

  In the above description, a fixed relationship is set with respect to the relationship between the number of inclined grooves 161G and 164G and the number of inclined grooves 162G and 163G. However, the present invention is limited to such a form. Not. In order to enjoy the same effect as described above, for example, instead of or in addition to the number of formations, the “forming density” may be focused (for example, the formation density of the inclined grooves 161G and 164G may be changed to the inclined grooves 162G). For example, making the width of the inclined grooves 161G and 164G larger than the width of the inclined grooves 162G and 163G, etc. ) Is also possible.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a view having the same concept as in FIG. 3 and shows a different aspect of forming the inclined grooves. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the fourth embodiment will be described. An explanation will be added. Moreover, about the code | symbol used in drawing referred in the said 1st Embodiment, when the same object is pointed out also in drawing referred in 4th Embodiment, suppose that the same code | symbol is used.

  In the fourth embodiment, unlike the above-described embodiments, the thrust portion left facing portion 164, the thrust portion right facing portion 161, the anti-thrust portion left facing portion 162, and the anti-thrust portion right facing portion 163 are shown in FIG. Inclined grooves including such parallel portions (hereinafter simply referred to as “parallel grooves” for convenience of description) 164GE, 161GE, 162GE, and 163GE are formed. More specifically, each of the parallel grooves 161GE to 164GE has a parallel portion and an inclined portion, and the latter inclined portion is substantially the same as each of the embodiments described above. That is, the inclined portion extends from the upper side to the lower side in the figure toward the boundary lines B1 to B4. On the other hand, the parallel portion is formed so as to be connected to the inclined portion, and is formed so as to be “parallel” to the direction perpendicular to the axial direction of the piston 18.

  According to such a form, first, it is apparent that substantially the same operational effects as those of the first to fourth embodiments can be obtained because the parallel grooves 161GE to 164GE include the inclined portion.

  Further, according to the fourth embodiment, the following effects can be obtained in addition to the above. That is, in the parallel grooves 161GE to 164GE, the holding force of the lubricating oil is stronger than the inclined grooves 161G to 164G of the first to third embodiments due to the presence of the parallel portion. Here, “strong” holding force specifically means that, for example, the amount of lubricating oil retained is relatively large, or the lubricating oil can be retained for a relatively longer time.

  As a result, for example, it is possible to prevent a situation in which the supply amount of the lubricating oil flowing into the thrust portion 16S and the anti-thrust portion 16AS is extremely fluctuated as the degree of reciprocation (for example, speed) of the piston 18 changes. can do. Therefore, more stable operation of engine 150 can be performed.

  For the same reason (strong holding force), in the fourth embodiment, it is possible to prevent wear between the piston 18 and the inner surface 16N of the cylinder liner 16 when the engine 150 is started. The starting torque required sometimes can be kept small. According to the latter, the capacity of the starter motor SM can be further reduced. This is because in the fourth embodiment, the lubricating oil can stay in the parallel portion even when the engine 150 is stopped. That is, in the inclined grooves 161G to 164G of the above-described embodiments, when the engine 150 is left standing for a relatively long time, all the lubricating oil in the inclined grooves 161G to 164G is thrust portion 16S due to the action of gravity. As a result, the engine 150 flows out to the anti-thrust portion 16AS, and when the engine 150 is started, relatively large friction can be generated and the starting torque can be increased. However, in the fourth embodiment, due to the presence of the parallel part, the risk of suffering such a problem is greatly reduced.

(Fifth embodiment)
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram having the same concept as in FIG. 3, and shows a different formation mode of the inclined grooves. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the fifth embodiment will be described. An explanation will be added. In addition, regarding the reference numerals used in the drawings referred to in the first embodiment, the same reference numerals are used in the drawings referred to in the fifth embodiment when the same objects are indicated.

  In the fifth embodiment, as shown in FIG. 9, a part of the inclined grooves 161G to 164G formed in the upper part of the cylinder liner 16 in the drawing extends to the areas of the thrust part 16S and the anti-thrust part 16AS. (Hereinafter, the extended portions of the inclined grooves 161G to 164G are referred to as “extension grooves 161GL to 164GL”). Due to the presence of the extension grooves 161GL to 164GL, it can be said that in the fifth embodiment, the thrust portion 16S and the anti-thrust portion 16AS have a configuration corresponding to an example of the “concave portion” according to the present invention.

  According to such a form, the following effects can be obtained. First, generally, the combustion temperature is higher in the upper part of the cylinder liner 16 in the figure (see FIG. 1), and the wall temperature of the cylinder liner 16 is also higher accordingly. Therefore, even if the lubricating oil stays in the inclined grooves 161G to 164G, it is highly likely that it will evaporate, and as a result, there is a greater risk of the lack of lubricating oil in that portion (by the way, the evaporated lubricating oil Oil will be sent into the exhaust manifold 30). In addition, since the speed of the piston 18 is “0” above the cylinder liner 16, particularly in the vicinity of the top dead center of the piston 18, a solid lubrication state is generated between the inner surface 16 </ b> N and the piston 18 above the cylinder liner 16. (See FIG. 4 above). As described above, in the vicinity of the upper side of the cylinder liner 16, there is a high possibility that a large amount of wear is generated between the cylinder liner 16 and the piston 18.

  However, in FIG. 9, since the extension grooves 161GL to 164GL as described above are formed in the thrust portion 16S and the anti-thrust portion 16AS, the retention amount of the lubricating oil above the cylinder liner 16 becomes relatively large. The evaporation is difficult to occur. In addition, the presence of more lubricating oil prevents the occurrence of a solid lubricating state as much as possible. Therefore, in the fifth embodiment, it is possible to prevent a large friction from occurring between the inner surface 16N above the cylinder liner 16 and the piston 18.

  The extension grooves 161GL to 164GL have a length LL shown in FIG. 9 that extends from the top of the piston 18 to the portion where the oil ring 182 is formed (hereinafter referred to as “the upper portion of the piston” for convenience). It is preferable that it is formed so as to be within the matching range. In this case, the lubricating oil staying in the extension grooves 161GL to 164GL is sealed by the oil ring 182 or the compression ring 181 at the upper part of the piston, so that the prevention of evaporation is better achieved. At the same time, the piston skirt portion 183 remains opposed to the thrust portion 16S and the anti-thrust portion 16AS having relatively smooth surface properties as in the above-described embodiments. Can be enjoyed.

(Sixth embodiment)
Hereinafter, a sixth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a view having the same concept as in FIG. 3 and shows a different aspect of forming the inclined groove, and FIG. 11 is a cross-sectional view taken along the line DD ′ of FIG. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the sixth embodiment will be described. An explanation will be added. In addition, regarding the reference numerals used in the drawings referred to in the first embodiment, the same reference numerals are used in the drawings referred to in the sixth embodiment when the same objects are indicated.

  First, in the sixth embodiment, as shown in FIG. 10, there is no particular difference from FIG. 3 in the planar formation of the inclined grooves 161G to 164G. The sixth embodiment is characterized by the “depth” of the inclined grooves 161G to 164G as shown in FIG. That is, the inclined grooves 161G to 164G are deeper in the portion corresponding to the vicinity of the top dead center and the bottom dead center of the piston 18 as shown in FIG. 11, and the portions corresponding to the portions other than the vicinity of the top dead center and the bottom dead center. In, it is formed shallower. In addition, the depth of the inclined grooves 161G to 164G arranged in the vertical direction in the figure is formed so as to gradually change. More specifically, the depth of the inclined grooves 161G to 164G located in the substantially central portion in the vertical direction in the drawing is the shallowest, and the depth of the inclined grooves 161G to 164G is increased in the upward and downward directions in FIG. The depth is gradually getting deeper. In FIG. 11, this state is particularly expressed as being enveloped by the curve DC.

  According to such a form, the following effects can be obtained. That is, first, as described with respect to the fifth embodiment, near the top dead center of the piston 18, the speed of the piston 18 becomes “0”, so that the inner surface 16 N above the cylinder liner 16 and the piston 18 Individual lubrication is likely to occur between them. This also occurs in the vicinity of the bottom dead center of the piston 18. However, since there is a relatively large amount of lubricating oil in the vicinity of the bottom dead center of the piston 18 compared to the vicinity of the top dead center, it is relatively better than the individual lubrication state that can occur near the top dead center. It is considered that a proper lubrication state is realized. On the other hand, in the vicinity of the center in the vertical direction in the figure, the speed of the piston 18 takes a maximum value, and therefore there is a high possibility that a preferable lubrication state, that is, a fluid lubrication state will appear (see FIG. 4). In summary, the most severe individual lubrication state is near the top dead center of the piston 18, while the preferred fluid lubrication state is near the center, and the lubrication state between them is near the bottom dead center. It is thought that it becomes. Therefore, it can be said that greater wear is likely to occur near the top dead center and near the bottom dead center of the piston 18 compared to the central portion, and as a result, portions having different wear states occur in the same cylinder. The fear increases.

  However, in the sixth embodiment, the possibility of suffering such a problem is extremely small. That is, the depth of the inclined grooves 161G to 164G is increased near the top dead center and the bottom dead center of the piston 18 in which an individual lubrication state or a state close to this occurs between the cylinder liner 16 and the piston 18. Therefore, the amount of lubricating oil retained in the portion is relatively large, and therefore, an individual lubrication state or a state close to this appears between the inner surface 16N of the cylinder liner 16 and the piston 18. It can be prevented in advance. Thus, according to the sixth embodiment, it is possible to prevent a situation in which the degree of wear differs between the top dead center and the bottom dead center of the piston 18 and the vicinity of the central portion.

  In addition, how to provide the difference in the depth of the inclined grooves 161G to 164G is not limited to the above-described form. For example, assuming that regions R1, R2,..., Rn including one or a plurality of inclined grooves 161G to 164G are provided along the vertical direction of the cylinder liner 16 in the figure, the regions R1, R2,. According to another, the depth of the inclined grooves 161G to 164G may be different (that is, the depth of the inclined grooves included in an arbitrary region Rm (where m = 1, 2,..., N)) All become the same). Further, as described above, there is a difference in the risk of solid lubrication between the vicinity of the top dead center and the bottom dead center of the piston 18, and accordingly, the depth of the inclined grooves 161G to 164G is determined accordingly. A difference may be provided. For example, in the form of an inclined groove formed near the top dead center, an inclined groove formed near the center, and an inclined groove formed near the bottom dead center, the depth becomes smaller. In some cases, the inclined grooves formed near the bottom dead center and the central portion have the same depth, but only the inclined grooves formed near the top dead center are formed deeper than that. Etc. may be adopted.

  Further, as specific values of the depths of the inclined grooves 161G to 164G, for example, the depth near the top dead center is about 20 to 30 μm, the depth near the center is about 2 to 3 μm, and the depth near the bottom dead center is It should be about 10 μm.

(Seventh embodiment)
The seventh embodiment of the present invention will be described below with reference to FIG. Here, FIG. 12 is a view having the same concept as in FIG. 3 and shows a different aspect in the thrust portion and the anti-thrust portion. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the seventh embodiment will be described. An explanation will be added. Moreover, about the code | symbol used in drawing referred in the said 1st Embodiment, suppose that the same code | symbol is used when pointing to the same object also in drawing referred in 7th Embodiment.

  In the seventh embodiment, as shown in FIG. 12, shot blasting is applied to the thrust portion 16SB and the anti-thrust portion 16ASB. Thereby, on the surfaces of the thrust portion 16SB and the anti-thrust portion 16ASB, for example, depressions or pits having a depth of about 2 to 30 μm (corresponding to an example of the “concave portion” in the present invention) are formed. Compared with each embodiment, the surface roughness is relatively large.

  According to such a form, the lubricating oil supplied from the inclined grooves 161G to 164G to the thrust portion 16SB and the anti-thrust portion 16ASB is more strongly held in the thrust portion 16SB and the anti-thrust portion 16ASB. The lubricity between both the parts 16SB and 16ASB and the piston skirt part 183 can be improved. Incidentally, such operational effects can be enjoyed in substantially the same manner in the fifth embodiment in which the extension grooves 161GL to 164GL are provided.

  In addition, in 7th Embodiment, it is good to devise the distribution of the said dent on the surface of thrust part 16SB and anti-thrust part 16ASB. That is, as mentioned in the fifth and sixth embodiments, since the piston 18 reciprocates, the lubrication state with the cylinder liner 16 may be preferable or deteriorated depending on the position of the piston 18. There is also a case. Therefore, in the portion where the speed of the piston 18 is higher, the dent formation density is made smaller or shallower, while in the portion where the speed is lower, the dent formation density is made higher, or It is possible to adopt a form such as deepening. Thereby, a uniform lubrication state is realizable in any part. From this point of view, it can be considered that the extension grooves 161GL to 164GL in the fifth embodiment show a preferable example as a formation mode of the “concave portion” in the present invention.

  Further, the cross-sectional shape of the recess is preferably formed by rounding a corner portion BRA formed by the surface S of the thrust portion 16SB or the anti-thrust portion 16ASB and the wall surface of the recess, as shown in FIG. . Thereby, the depression in the thrust portion 16SB or the anti-thrust portion 16ASB can be prevented from causing a problem that the movement of the piston skirt portion 183 and hence the piston 18 is disturbed. The same applies to the extension grooves 161GL to 164GL in the fifth embodiment.

(Eighth embodiment)
Hereinafter, an eighth embodiment of the present invention will be described with reference to FIGS. FIG. 14 is a view having the same concept as in FIG. 3, and shows a different aspect of forming the inclined groove, and FIG. 15 is a cross-sectional view taken along the line EE ′ of FIG. 14. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the eighth embodiment will be described. An explanation will be added. In addition, regarding the reference numerals used in the drawings referred to in the first embodiment, the same reference numerals are used in the drawings referred to in the eighth embodiment when the same objects are indicated.

  First, in the eighth embodiment, as shown in FIG. 14, there is no particular difference from FIG. 3 in the planar formation of the inclined grooves 161G to 164G. This eighth embodiment is characterized by the “cross-sectional shape” of the inclined grooves 161G to 164G as shown in FIG. That is, the cross-sectional shapes of the inclined grooves 161G to 164G are substantially triangular as shown in FIG. 15, and these are connected to form a sawtooth shape as a whole. More specifically, focusing on one cross-sectional shape, the upper side (corresponding to an example of the “first side” in the present invention) of the cross-sectional shape is perpendicular to the axis of the piston 18. The middle lower side (corresponding to an example of the “second side” in the present invention) is directed obliquely downward and intersects the axis obliquely.

  According to such a form, the following effects can be obtained. That is, first, since the lower side of the sectional shape of the inclined grooves 161G to 164G obliquely intersects the axis of the piston 18, the lubricating oil in these inclined grooves 161G to 164G is oil ring 182. (See FIG. 1 or FIG. 2). That is, it is easy to supply lubricating oil between the cylinder liner 16 and the piston 18. Accordingly, since the supply amount of the main lubricating oil to be introduced into the cylinder liner 16 may be reduced, the consumption amount of the lubricating oil can be reduced and, for example, an oil jet can be omitted. The cost of the engine 150 can be reduced.

  On the other hand, since the upper side of the sectional shapes of the inclined grooves 161G to 164G in the drawing is perpendicular to the bore axis, the lubricating oil in the inclined grooves 161G to 164G may be mixed into the combustion chamber 20. It has become difficult. Therefore, since the amount of lubricating oil sent to the exhaust manifold 30 can be relatively reduced, the emission can be improved.

  The cross-sectional shape as shown in FIG. 15 can be obtained, for example, by forming the end mill tip into a groove shape with an NC machining center and processing it.

(Ninth embodiment)
The ninth embodiment of the present invention will be described below with reference to FIGS. 16 and 17. FIG. 16 is a view having the same concept as in FIG. 3 and shows a different formation mode of the inclined grooves, and FIG. 17 is a partially enlarged view of FIG. In the following description, since the configuration and operation related to the engine described in the first embodiment are the same, the description thereof will be simplified or omitted, and only the characteristic configuration in the ninth embodiment will be described. An explanation will be added. In addition, regarding the reference numerals used in the drawings referred to in the first embodiment, the same reference numerals are used in the drawings referred to in the ninth embodiment when the same objects are indicated.

In the ninth embodiment, as shown in FIGS. 16 and 17, inclined grooves (hereinafter simply referred to as “circular grooves”) 161GC to 164GC that do not include a straight portion are formed. More specifically, among these circular arc grooves 161GC to 164GC, the circular arc grooves 161G and 162G have the arc vertices drawn as a whole separating the thrust portion right facing portion 161 and the anti-thrust portion left facing portion 162 on the boundary line B5. The circular arc grooves 163G and 164G are formed so that the vertex of the circular arc drawn by the whole divides the anti-thrust portion right facing portion 163 and the thrust portion left facing portion 164 on the boundary line B6. Has been. Also,
According to such a form, the following effects can be obtained. That is, first, even in the arc grooves 161GC to 164GC as in the ninth embodiment, the lubricating oil is supplied to the thrust portion 16S and the anti-thrust portion 16AS as in the above embodiments. The same effect can be obtained. Further, in the arc grooves 161GC to 164GC of the ninth embodiment, as described above, the arc vertices drawn by the arc grooves 161GC and 162GC or the arc grooves 163GC and 164GC as a whole are on the boundary lines B5 and B6. Therefore, the portion becomes a portion parallel to the direction perpendicular to the axis of the piston 18 and the holding force of the lubricating oil is increased. In other words, according to the ninth embodiment, substantially the same effect as described with respect to the fourth embodiment (that is, prevention of extreme fluctuations in the supply amount of lubricating oil and generation of wear at the start of the engine 150). Prevention).

  And especially in 9th Embodiment, since the shape of the groove | channel which should supply lubricating oil to the thrust part 16S and anti-thrust part 16AS is made into circular arc shape, the lubricating oil stored in the said groove | channel is used for the thrust part 16S. And it can supply to anti-thrust part 16AS more quickly and without stagnation. Further, the fact that the lubricating oil is quickly supplied to the thrust portion 16S and the anti-thrust portion 16AS means that both the portions 16S and 16AS hold abundant lubricating oil. Oil film thickness between 16AS and piston skirt part 183 becomes large, and generation of noise, vibration, etc. can be controlled. In addition, since the contact between the arc grooves 161GC to 164GC and the oil ring 183 becomes smoother, it can be said that the lubricating oil is scraped out from the arc grooves 161GC to 164GC more easily. . As a result, according to the ninth embodiment, as a whole, it is possible to achieve better low friction between the cylinder liner 16 and the piston 18 as a whole.

  In addition, as a more preferable shape of the arc grooves 161GC to 164GC, for example, a shape as shown in FIG. 17 may be used. In FIG. 17, the width GW (0) of the groove at the apex located on the boundary lines B5 and B6 is the largest, and the length l along this arc groove 161GC or 162GC, or 163GC or 164GC from this portion. The arc groove 161GC or 162GC, or 163GC or 164GC is formed so that the width GW (l) of the groove gradually decreases as it increases. In particular, according to such a shape, more lubricating oil can be held at the apex portion having the larger width GW (0), so that the operational effect resulting from the increase in the holding power of the lubrication can be obtained. You can enjoy it more reliably. Further, other operational effects (such as rapid supply of lubricating oil to the thrust portion 16S or the ease of scraping) can be enjoyed more effectively.

  Further, the arc grooves 161GC to 164GC as shown in FIGS. 16 and 17 can be created by, for example, inclining and cutting a cutter (end mill) having a diameter smaller than the bore inner diameter.

  In addition, in this invention, it cannot be overemphasized that the form which implements each of the above-mentioned each embodiment separately may be employ | adopted, and the embodiment implemented in combination of some may be employ | adopted. For example, the arc grooves 161GC to 164GC (the ninth embodiment) are combined with a form (eighth embodiment) in which the cross-sectional shape is substantially triangular, or the inclined grooves 161G to 164G (second embodiment) are formed in a stepwise manner. And the like (seventh embodiment) are combined with the thrust portion and the anti-thrust portion (seven or more embodiments may be combined).

  The present invention is not limited to the above-described embodiment, and can be appropriately changed within a scope not departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an engine accompanying such a change is also applicable. It is included in the technical scope of the present invention.

1 is a schematic configuration diagram of a power output apparatus according to a first embodiment. It is the perspective view which extracted and drawn only the piston and cylinder liner shown in FIG. FIG. 3 is a development view showing an inner surface of a cylinder liner as a table. It is a qualitative Strivek diagram. FIG. 4 is a diagram having the same concept as in FIG. 3, and shows a configuration in which inclined grooves are formed differently (an embodiment in which inclined grooves sandwiching a thrust portion or an anti-thrust portion from both sides are formed in steps). It is explanatory drawing which shows the more detailed shape of the piston skirt part shown in FIG.1 and FIG.2. FIG. 3 is a diagram having the same concept as in FIG. 3, except that the inclined grooves are formed differently (the number of inclined grooves in the thrust portion left facing portion and the thrust portion right facing portion, and the counter thrust portion left facing portion and the anti thrust portion right facing). The aspect from which the number of the inclined grooves of a part differs is shown. FIG. 4 is a diagram having the same concept as in FIG. 3, and shows a configuration in which the inclined grooves are different (parallel grooves). FIG. 4 is a diagram having the same concept as in FIG. 3, and shows a different inclined groove formation mode (extension groove). FIG. 4 is a diagram having the same concept as in FIG. 3, and shows a configuration in which the inclined groove is formed differently (an embodiment in which the depth of the inclined groove changes). It is DD 'sectional drawing of FIG. FIG. 4 is a diagram having the same concept as in FIG. 3, and shows an example in which the inclined grooves are formed differently (an aspect in which shot blasting is applied to the thrust portion and the anti-thrust portion). It is a figure which shows the cross-sectional shape of a hollow. FIG. 4 is a diagram having the same concept as in FIG. 3, and shows a configuration in which inclined grooves are formed differently (an embodiment in which the sectional shape of the inclined grooves is substantially triangular). It is EE 'sectional drawing of FIG. It is a figure of the same meaning as FIG. 3, Comprising: The formation aspect of an inclination groove | channel (arc groove | channel) is shown. FIG. 17 is a partially enlarged view of FIG. 16.

Explanation of symbols

150 ... Engine 18 ... Piston 183 ... Piston skirt part 16 ... Cylinder liner 16N ... Inner surface of cylinder liner 16S, 16SB ... Thrust part 16AS, 16ASB ... Anti-thrust part 161 ... Thrust part right opposing part 162 ... Anti-thrust part left opposing part 163 ... Anti-thrust part right facing part 164 ... Thrust part left facing part 161G to 164G ... Inclined groove 161GE to 164GE ... Parallel groove 161GL to 164GL ... Extension groove 161GC to 164GC ... Arc groove B1, B2 ... (Thrust part and thrust part right opposite) Boundary lines B3, B4 ... (Anti-thrust part and anti-thrust part right-facing part and anti-thrust part left-facing part) Boundary line B5 ... Boundary line B6 ... (Thrust portion left facing portion and anti-thrust) Part of the right opposing portion) border

Claims (9)

A piston,
A cylinder liner having a space in which the piston reciprocates, and a first portion comprising a thrust portion and an anti-thrust portion of the inner surface of the cylinder liner facing the piston;
A second portion having a surface roughness greater than the surface roughness of the first portion, and comprising a portion other than the thrust portion and the anti-thrust portion of the inner surface;
An inclined groove formed in the second part, extending from the top dead center side of the piston toward the bottom dead center side, and obliquely intersecting a boundary line of the first part and the second part;
An engine comprising: lubricating oil supply means for supplying lubricating oil to the space.   The engine according to claim 1, wherein there are a plurality of the inclined grooves, and the plurality of inclined grooves do not intersect each other. The second portion includes a first thrust facing portion and a second thrust facing portion sandwiching the thrust portion,
On the boundary line between the first thrust facing portion and the thrust portion, a first thrust portion concavo-convex row that appears based on the inclined groove formed in the first thrust facing portion, the second thrust facing portion, and the thrust portion On the boundary line of the second thrust portion, the second thrust portion concavo-convex rows appearing on the basis of the inclined grooves formed in the second thrust facing portion are the positions of the convex and concave portions constituting the first thrust portion concavo-convex rows, respectively. 3. The engine according to claim 1, wherein the second thrust portion concavo-convex rows are displaced from each other. The second portion includes a first thrust facing portion and a second thrust facing portion that sandwich the thrust portion, and a first anti-thrust facing portion and a second anti-thrust facing portion that sandwich the anti-thrust portion,
The number of the inclined grooves formed in the first thrust facing portion and the second thrust facing portion is greater than the number of the inclined grooves formed in the first anti-thrust facing portion and the second anti-thrust facing portion. The engine according to any one of claims 1 to 3, wherein the number of the engine is large.   The engine according to any one of claims 1 to 4, wherein the inclined groove includes a parallel portion parallel to a direction perpendicular to the axis of the piston.   The engine according to any one of claims 1 to 5, wherein a recess is formed in the first portion.   The engine according to claim 6, wherein the recess is formed in a portion of the inner surface of the cylinder liner corresponding to the top dead center of the piston.   The depth of the inclined groove formed in a portion corresponding to the top dead center of the piston on the inner surface of the cylinder liner is deeper than the depth of the inclined groove formed in the other portion. Item 8. The engine according to any one of Items 1 to 7. The sides constituting the cross-sectional shape of the inclined groove are:
A first side extending from the surface of the second portion toward the axis of the piston and perpendicular to the axis or toward the top dead center of the piston;
2. A second side extending from one end of the first side or a point in the vicinity thereof toward the surface and extending from the top dead center side toward the bottom dead center side. The engine as described in any one of thru | or 7.

Images