JP2012215138A - Oil supply device of piston for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil supply device of a piston for an internal combustion engine, which is capable of supplying an optimal amount of lubricating oil for forming an oil film to a land, while simplifying a structure of the oil supply device.SOLUTION: The oil supply device includes: an oil guide path 30 having an opening 30a at a lower end while extending in the vertical direction at a portion of an air intake side skirt 12a; oil supplying paths 14, 15, one end of which communicates with an upper end of the oil guide path 30, and the other end of which communicates with the land 23; and a lubricating nozzle 32, which is disposed in an inclined state of shifting to the center side of the piston 10 as extending upward such that a nozzle tip may oppose to the opening 30a when the piston 10 is positioned in the vicinity of a bottom dead center, and which can inject the lubricating oil to the opening 30a. At a lower portion from the opening 30a of the oil guide path 30, an oil flow direction conversion part 31 is provided which guides the lubrication oil injected from the lubricating nozzle 32 to the side of the air intake side skirt 12a oppositely to the nozzle tip, when the piston 10 is lifted and moved from the position in the vicinity of the bottom dead center.

Description

  The present invention relates to an oil supply device for a piston for an internal combustion engine that reciprocates in a cylinder bore, and in particular, an oil guiding path for guiding lubricating oil injected from a lubricating nozzle to a land portion and an oil for guiding one skirt portion side. The present invention relates to an oil supply device for a piston for an internal combustion engine including a flow direction conversion unit.

  2. Description of the Related Art Conventionally, pistons of internal combustion engines (hereinafter referred to as engines) include a piston crown portion formed from a top portion that receives an explosion gas pressure of combustion gas, a land portion provided with a piston ring groove around the piston crown portion, and a piston pin. A pair of pin bosses connected to the small end of the connecting rod and a pair of skirts for guiding the reciprocating motion of the piston are formed. In particular, since the top portion of the piston crown portion is exposed to high-temperature combustion gas, the piston is cooled by providing an oil jet for injecting cooling oil to the back surface of the piston crown portion.

  Normally, two compression ring grooves for mounting the top ring and the second ring and an oil ring groove for mounting the oil ring are formed between the land portions of the piston. When the piston moves up (moves toward the top dead center), this oil ring lifts the lubricating oil to form an oil film on the inner peripheral surface of the cylinder bore, and the piston moves down (moves toward the bottom dead center). In doing so, it has a function of scraping off excess lubricating oil, so-called surplus oil, while leaving an oil film required for lubricating the inner peripheral surface of the cylinder bore. Therefore, if the excess oil is not scraped off by the oil ring, the excess oil stays in the land between the second ring groove and the oil ring groove, and the retained excess oil is sucked into the combustion chamber. Since it is burned in the combustion chamber, the oil consumption is increased.

  The engine lubrication device described in Patent Document 1 includes a plurality of communication passages that penetrate the land portion between the second ring groove and the oil ring groove of the piston in the radial direction and communicate between the outer periphery of the land portion and the inside of the piston. An oil reservoir having an opening through which the lubricating oil injected from the oil jet can be introduced on the back side of the piston crown and communicating with the piston inward opening of the plurality of communication passages; An oil induction limiting portion is provided that guides the lubricating oil to the opening when the piston moves up, and restricts introduction to the opening when the pinton moves down. In this engine lubrication device, the lubricating oil injected from the oil jet when the piston moves up is introduced into the oil reservoir, and the lubricating oil injected from the oil jet when the piston moves down restricts the oil from entering the oil reservoir. Therefore, the amount of oil staying in the space above the oil ring is adjusted appropriately.

JP 2010-84576 A

  The engine lubrication device of Patent Document 1 is provided with a piston-side convex portion provided with an oil guiding slope and an oil-limiting slope on the back surface of the piston portion, and by providing a connecting rod-side convex portion at the small end portion of the connecting rod, the pinton ascending movement Sometimes the connecting rod side convex part guides the lubricating oil to the oil guiding slope side, and when the pinton moves down, the connecting rod side convex part guides the lubricating oil to the oil limiting slope side. However, when supplying the lubricating oil to the land portion, this lubricating device forcibly changes the traveling direction of the lubricating oil by causing the lubricating oil to collide with the connecting rod side convex portion and the oil guiding slope, Since the lubricating oil path is such that the stored oil is supplied to the land portion after being stored in the reservoir portion, the structure of the piston, connecting rod and the like may be complicated, and the manufacturing cost may be increased. Moreover, in the lubricating oil path of Patent Document 1, since the lubricating oil collides with the connecting rod side convex portion and the oil guiding slope and is supplied to the opening, the hydraulic pressure loss of the lubricating oil at the time when the lubricating oil was supplied to the opening In order to supply lubricating oil to the land portion, a large-capacity oil pump may be required.

  As a result of repeated diligent experiments and examinations by the present inventors, an oil oil film that does not excessively or insufficiently lubricate the inner peripheral surface of the cylinder bore with the amount of lubricating oil supplied to the land portion when the piston is in the vicinity of the bottom dead center is obtained. It was verified that it can be formed. That is, even if the oil is supplied while the pinton is moving upward, the lubricating oil supplied after the initial rising is less effective in forming an optimal oil film on the inner peripheral surface of the cylinder bore. Oil may accumulate in the land as surplus oil, which may deteriorate oil consumption.

  An object of the present invention is to provide an oil supply device for a piston for an internal combustion engine that can supply a lubricating oil amount optimal for forming an oil oil film to a land portion while simplifying the structure of the oil supply device.

  An oil supply device for a piston for an internal combustion engine according to claim 1 comprises a piston crown portion, a pair of pin boss portions formed on the back surface of the piston crown portion and connected to a crankshaft via a connecting rod, and the piston crown In an internal combustion engine piston oil supply device having a pair of skirt portions extending downward from the portion, and reciprocatingly moving in the cylinder bore, the at least one pin boss portion extends vertically to one skirt portion side portion and opens to the lower end. An oil guiding path having one end communicating with the upper end of the oil guiding path, and the other end communicating with a peripheral surface between the oil ring groove and the compression ring groove of the piston crown portion, and the piston When near the dead center, the upper end of the nozzle faces the piston center side so that the nozzle tip faces the opening of the oil guide path And a lubricating nozzle that is capable of injecting lubricating oil into the opening, and the piston is moved upward from a position near the bottom dead center in a portion below the opening of the oil guide path. In this case, an oil flow direction changing portion for guiding the lubricating oil sprayed from the lubricating nozzle to the one skirt portion side is provided opposite to the nozzle tip.

  In this piston oil supply device for an internal combustion engine, when the piston is located at a position near the bottom dead center, the nozzle tip is arranged in an inclined shape so as to move upward toward the piston center so as to face the opening of the oil guide path. When the piston moves upward from the position near the bottom dead center, the oil flow direction changing portion guides the lubricating oil to the one skirt portion side. Therefore, the lubricating oil is supplied to the peripheral surface between the oil ring groove and the compression ring groove only during a limited period when the piston is in the vicinity of the bottom dead center, and the piston is in the rising process. However, the lubricating oil is not supplied during a period other than the position near the bottom dead center.

According to a second aspect of the present invention, in the first aspect of the present invention, the oil guide passage and the oil flow direction changing portion are formed in the pair of pin boss portions, respectively, and a plurality of oil supply passages communicate with the oil guide passage of each pin boss portion. It is characterized by that.
According to a third aspect of the present invention, in the first or second aspect of the present invention, the oil guiding path is formed in an inclined shape so as to move upward toward the piston center, and the oil flow direction changing portion is connected to an axis of the oil guiding path. It is characterized in that it is formed in an inclined shape so as to move upward toward the one skirt portion so as to intersect.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the cooling oil is disposed at the lower end portion of the cylinder bore on the other skirt portion side, and the cooling oil is disposed on the back surface of the piston crown portion. A cooling nozzle for injecting cooling oil from the lower side to the back surface of the piston crown portion so as to flow from the side to the one skirt portion side, and the oil flow direction changing portion is provided with the direction-converted lubricating oil. The back surface of the piston crown portion is formed to flow in the same direction as the cooling oil.

  According to the first aspect of the present invention, lubricating oil is supplied to the circumferential surface between the oil ring groove and the compression ring groove only during a period in which the piston is in the vicinity of the bottom dead center, Lubricating oil is not supplied except during the position near the dead center, so the optimal amount of lubricating oil is supplied to the peripheral surface between the oil ring groove and the compression ring groove so that there is no excess or shortage of oil film formation on the inner peripheral surface of the cylinder bore. In addition, the sliding resistance of the piston can be reduced while suppressing the supply of surplus oil unnecessary for piston lubrication. In addition, when the piston moves up from the position near the bottom dead center, the oil flow direction changing portion guides the lubricating oil to the one skirt portion side, so that the cooling performance of the piston is enhanced by using the lubricating oil. Can do. Also, by improving the structure of the two parts, the lubricating nozzle and piston, the lubricating oil can be supplied directly from the nozzle tip to the oil guiding part formed on the pin boss, thus simplifying the structure of the oil supply device The manufacturing cost can be reduced.

According to the second aspect of the present invention, since a plurality of oil supply passages communicate with the oil guide portions of the pin boss portions, the amount of lubricating oil can be efficiently supplied to the peripheral surface between the oil ring groove and the compression ring groove. Furthermore, the sliding resistance of the piston can be further reduced.
According to the invention of claim 3, the oil guiding portion and the oil flow direction changing portion can be formed without largely changing the basic shape of the piston, and the manufacturing cost can be reduced.

  According to the invention of claim 4, the cooling performance of the piston is further enhanced by the synergistic effect of the lubricating oil and the cooling oil without obstructing the flow of the cooling oil flowing through the back surface of the piston crown portion. can do.

It is a whole block diagram of the oil supply apparatus of the piston which concerns on Example 1 of this invention. It is the figure which looked at the piston from the lower part. It is an assembly drawing of a piston and a connecting rod. It is a side view of a piston. It is the VV sectional view taken on the line of FIG. It is a principal part enlarged view of FIG. It is a graph which shows the relationship between a piston position and the supply timing of lubricating oil. It is a figure which shows the piston and the nozzle for lubrication of a bottom dead center vicinity position. It is a figure which shows the piston and the nozzle for lubrication of the oil flow direction conversion initial position. It is a figure which shows the piston and nozzle for lubrication of the oil flow direction change final position. It is a figure which shows the piston and the nozzle for lubrication of the bottom dead center position which concern on Example 2. FIG. It is a figure which shows the piston and the nozzle for lubrication in an oil flow direction conversion period.

  Hereinafter, modes for carrying out the present invention will be described based on examples. In the following description, the vertical direction in the figure is the vertical direction, the intake side of the engine is the front, and the exhaust side is the rear.

Hereinafter, Example 1 of the present invention will be described with reference to FIGS.
As shown in FIG. 1, an oil supply apparatus 1 of this embodiment supplies lubricating oil and cooling oil to a piston 10 of a multi-cylinder engine of a vehicle, for example, a horizontal in-line 4-cylinder gasoline reciprocating engine E. It is. FIG. 1 shows a state where the piston 10 has finished the lowering process and has reached the bottom dead center position.

  The engine E includes a cylinder head (not shown), a cylinder block 2, an oil pan (not shown), and the like. An intake side cam shaft (not shown) and an exhaust side cam shaft (not shown) are pivotally supported by the cylinder head. A rotational driving force is transmitted from the crankshaft 3 to these camshafts, and intake and exhaust valves (not shown) linked to the respective camshafts are reciprocated. The engine E is mounted in the engine room of the automobile so that the intake camshaft is in front of the vehicle in the traveling direction, and is arranged in a rear slant shape that inclines rearward as it moves upward.

  As shown in FIG. 1, the cylinder block 2 includes a crankshaft 3, four connecting rods (connecting rods) 4, four cylinder bores 5, four pistons 10, and a pair of lubricating oil injections for each cylinder. A device 7 and one cooling oil injection device 8 for each cylinder are provided. The cylinder block 2 forms a crank chamber that houses the crankshaft 3.

  The crankshaft 3 includes a journal portion (not shown), a pin portion 3a, an arm portion (not shown), and the like, and rotates in a direction indicated by an arrow A in the drawing. The crankshaft 3 is pivotally supported by the cylinder block 2 via a bearing portion. A large end portion 4a formed at the lower end of the connecting rod 4 is rotatably connected to the pin portion 3a via a bearing portion. A piston 10 is swingably connected to a small end portion 4 b formed at the upper end of the connecting rod 4 via a piston pin 6 disposed in parallel with the crankshaft 3. The cylinder bore 5 is formed in a substantially cylindrical shape.

  As shown in FIGS. 1 to 6, the piston 10 includes a piston crown portion 11, a pair of skirt portions 12 a and 12 b, a pair of pin boss portions 13, and a plurality of oil supply passages 14 and 15. . The piston 10 is formed in a bottomed cylindrical shape that opens downward, and is made of, for example, an aluminum alloy. The piston 10 is inserted into the cylinder bore 5 so as to be reciprocated in the vertical direction in the cylinder bore 5.

  The piston crown portion 11 includes a top surface 21, a back surface 22, a land portion 23, three ring grooves 24 to 26, and the like. An intake side recess 22a and an exhaust side recess 22b are formed on the back surface 22. The intake-side recess portion 22a and the exhaust-side recess portion 22b are respectively formed in the intake-side portion and the exhaust-side portion of the back surface 22 so as to be curved in a curved shape toward the top surface 21, and the area of the intake-side recess portion 22a in plan view. Is formed smaller than the area of the exhaust-side recess 22b. The intake-side recess portion 22a and the exhaust-side recess portion 22b are configured to smoothly connect at the center position of the back surface 22.

  The intake side skirt portion 12a and the exhaust side skirt portion 12b are formed on the intake side portion and the exhaust side portion of the piston 10 so as to extend downward from the lower end of the piston crown portion 11, respectively. Therefore, when the piston 10 reciprocates in the vertical direction, the pair of skirt portions 12a and 12b are guided by the inner peripheral surface of the cylinder bore 5, so that the piston 10 swings back and forth around the piston pin 6 as a rotation center. It is suppressed.

  On the outer periphery of the piston crown portion 11, a land portion 23 is formed at a position between the top surface 21 and the skirt portions 12a and 12b. In the land portion 23, a top ring groove 24, a second ring groove 25, and an oil ring groove 26 are formed. The top ring groove 24 is formed at a position closest to the top surface 21 and is fitted with a top ring 16 (first compression ring). The second ring groove 25 is formed at a lower position than the top ring groove 24, and a second ring 17 (second compression ring) is mounted thereon. The oil ring groove 26 is formed at a lower position than the second ring groove 25, and the oil ring 18 is attached thereto. For convenience of explanation, the rings 16 to 18 are not shown except for FIG.

  As shown in FIG. 3, the top ring 16 and the second ring 17 are formed in a substantially C shape, and are fitted into the top ring groove 24 and the second ring groove 25 in a state where they are forcibly elastically compressed and deformed, respectively. Thereby, both the rings 16 and 17 contact the inner peripheral surface of the cylinder bore 5 with a constant restoring force, and the amount of blow-by gas leaking from the combustion chamber of the engine E to the crank chamber is suppressed. The oil ring 18 is formed in a substantially C shape like both the rings 16 and 17 and is fitted into the oil ring groove 26 in a state where it is forcibly elastically deformed. As a result, the oil ring 18 contacts the surface of the cylinder bore 5 with a certain restoring force, and when the piston 10 is in the ascending process, the oil is lifted to form an oil film on the inner peripheral surface of the cylinder bore 5, and the piston 10 descends. During the process, excess oil is scraped off while leaving the amount of lubricating oil necessary for optimal oil film formation.

  As shown in FIGS. 1 to 6, the piston crown portion 11 is formed with a pair of pin boss portions 13 extending downward from the back surface 22 at a position between the pair of skirt portions 12 a and 12 b. One pin boss portion 13 is arranged in a position parallel to the axis of the piston pin 6 and closer to the front side with respect to the center of the piston 10, and the other pin boss portion 13 is parallel to the axis of the piston pin 6 with respect to the center of the piston 10. And it arrange | positions in the position near rear side, and both the pin boss | hub parts 13 are formed in parallel so that the center of piston 10 may be pinched | interposed.

  Each of the pair of pin boss portions 13 includes a base portion 27 extending downward from the back surface 22, a pin receiving portion 28 formed at a lower portion of the base portion 27, a pin hole 29 provided in the pin receiving portion 28, and the like. . As shown in FIG. 3, the pin hole 29 supports the piston pin 6 that is rotatably inserted into the small end portion 4 b of the connecting rod 4 via the bearing portion. Since the pair of pin boss portions 13 are connected to the connecting rod 4 via the piston pin 6, the rotational driving force of the crankshaft 3 is transmitted to the piston 10 via the connecting rod 4, and the piston 10 moves up and down in the cylinder bore 5. Move up and down.

  As shown in FIGS. 1, 2, 5, and 6, each base portion 27 includes an oil guide passage 30 extending vertically from the lower end portion to the piston crown portion 11 on the intake side skirt portion 12 a side portion. Is provided. The oil guide path 30 is formed in an inclined shape that is substantially linear in the direction orthogonal to the axis of the piston pin 6 and that moves upward toward the center of the piston 10.

  As shown in FIG. 6, the axis B of the oil guide path 30 is set to have an intersecting angle α with respect to the vertical straight line V parallel to the axis of the piston 10 in a side view. At the lower end of the oil guide path 30, a vertically long oval opening 30a is formed facing the inner peripheral surface of the intake side skirt portion 12a. The vertical width of the opening 30 a is set to be larger than half of the vertical width of the base portion 27. The oil guide path 30 is integrally formed with the pin boss portion 13 and is manufactured by machining with respect to the base portion 27 using a processing tool such as a drill.

  In the pin receiving portion 28, an oil flow direction changing portion 31 is formed below the lower end of the opening 30a of the oil guide path 30 and on the intake side skirt portion 12a side portion. The surface of the oil flow direction changing portion 31 is formed in a substantially flat shape, and is formed in an inclined shape so as to move upward toward the intake side skirt portion 12a in a side view.

  As shown in FIG. 6, the extended surface C of the surface of the oil flow direction changing portion 31 is set to have an intersecting angle β with respect to the vertical straight line V in a side view. As described above, when the piston 10 moves upward from the position near the bottom dead center (BDC), the oil flow direction changing portion 31 guides the lubricating oil injected from the lubricating oil injection device 7 toward the intake side skirt portion 12a. The induced lubricating oil flows on the back surface 22 of the piston crown portion 11 from the exhaust side skirt portion 12b side to the intake side skirt portion 12a side.

  As shown in FIGS. 1, 2, 5, and 6, a plurality of oil supply passages 14 and 15 are formed in the piston crown portion 11 corresponding to the respective oil guide passages 30. The plurality of oil supply passages 14 and 15 extend substantially linearly from the top (upper end) of each oil guide passage 30 in the direction orthogonal to the axis of the piston 10, and are land portions formed between the second ring groove 25 and the oil ring groove 26. It is formed to communicate up to 23. In this embodiment, the oil supply passage 14 and the oil supply passage 15 are formed so as to have the same axis, and the piston crown portion 11 is manufactured using a processing tool such as a drill.

  As shown in FIG. 1, the pair of lubricating oil injection devices 7 is mounted on the cylinder block 2 so as to be adjacent to the lower end of the intake side of each cylinder bore 5. Each of the pair of lubricating oil injection devices 7 is connected to an oil pump (not shown) of the engine E via an oil gallery 9a. Since the pair of lubricating oil injection devices 7 have the same structure, only one lubricating oil injection device 7 will be described in the following description.

  The lubricating oil injection device 7 includes a lubricating nozzle 32, a lubricating valve portion 33, a lubricating case portion 34, and the like. The lubrication nozzle 32 is formed by a tubular member extending from the outer position of the cylinder bore 5 toward the inner position of the cylinder bore 5, and is configured to be able to inject lubrication oil into the opening 30a. As shown in FIG. 6, the nozzle tip of the lubricating nozzle 32 is formed so that its axis is substantially the same axis as the axis B of the oil guide path 30, and when the piston 10 is in a position near the BDC, the oil guide path 30. When the piston 10 moves upward from a position near the BDC, the upper portion 30a is disposed in an inclined shape so as to face the oil flow direction changing portion 31 and move toward the piston 10 center side.

  The lubricating valve portion 33 includes a check valve inside the bolt member. The lubricating valve portion 33 is screwed into a screw hole formed in the cylinder block 2, and an opening formed at the tip thereof is communicated with the oil gallery 9a. When the oil supply pressure is a predetermined value in a state where the lubrication valve portion 33 is attached to the cylinder block 2, the lubrication valve portion 33 opens and the oil is lubricated through the oil passage in the lubrication case portion 34. It flows to the nozzle 32 for use. The lubricating oil injection device 7 can omit the lubricating valve portion 33 as a check valve.

  As shown in FIG. 1, one cooling oil injection device 8 is arranged for each cylinder bore 5. The cooling oil injection device 8 is connected to an oil pump of the engine E via an oil gallery 9b, and is configured to be able to inject cooling oil into the exhaust side recess 22b. The cooling oil injection device 8 is disposed at the lower end on the exhaust side of each cylinder bore 5. Therefore, the pair of lubricating oil injection devices 7 and the cooling oil injection devices 8 are laid out in a staggered manner with respect to the axis of the piston pin 6 in plan view.

The cooling oil injection device 8 includes a cooling nozzle 35, a cooling valve portion 36, a cooling case portion 7 and the like. The cooling nozzle 35 is formed of a tubular member extending from the outer position of the cylinder bore 5 toward the inner position of the cylinder bore 5. The cooling oil sprayed from the cooling nozzle 35 flows from the exhaust side recess 22b through the central portion of the back surface 22, reaches the intake side recess 22a, and drops into the crank chamber through the intake side skirt 12a.
The cooling valve portion 36 includes a check valve inside the bolt member. The cooling valve portion 36 is screwed into a screw hole formed in the cylinder block 2, and an opening formed at the tip is communicated with the oil gallery 9b. When the cooling valve portion 36 is attached to the cylinder block 2 and the oil supply pressure is equal to or higher than a predetermined value, the cooling valve portion 36 opens and the cooling oil passes through the oil passage in the cooling case portion 37. To the cooling nozzle 35.

Next, the operation of the oil supply device 1 will be described with reference to FIGS. 1 and 6 to 10.
As shown in FIGS. 1 and 6, when the piston 10 is in the BDC position, the axis of the nozzle tip of the lubrication nozzle 32 is formed so as to be substantially the same axis as the axis B of the oil guide path 30. The oil passes through the opening 30 a from the lubricating nozzle 32 and is directly introduced into the oil guide path 30. Since this lubricating oil is introduced into the oil guide passage 30 with almost no hydraulic loss, it flows through the oil supply passages 14 and 15 to reach the land portion 23 and reduces the sliding resistance of the piston 10. Yes.

  As shown in FIG. 8, when the piston 10 is in the vicinity of the BDC, for example, when the piston 10 moves up 8 mm from the BDC, the nozzle tip of the lubrication nozzle 32 maintains the facing state with the opening 30a. Is supplied from the oil guide path 30 to the land portion 23 via the oil supply paths 14 and 15. In the present embodiment, since the axis of the nozzle tip of the lubricating nozzle 32 is formed so as to be substantially the same axis as the axis B of the oil guide path 30, as shown in FIG. The operation starts from the end of the lowering process of the piston 10, which is the previous stage of BDC.

  As shown in FIG. 9, when the piston 10 is moved upward by a predetermined distance from the position near the BDC, the oil flow direction conversion initial position, for example, when the piston 10 is moved upward by 10 mm from the BDC, the nozzle tip of the lubricating nozzle 32 has an opening 30a. Is opposed to the intake-side skirt portion 12a side end of the oil flow direction changing portion 31. As a result, the lubricating oil sprayed from the lubricating nozzle 32 is rebounded on the surface of the oil flow direction changing portion 31, and the traveling direction is changed toward the intake side skirt portion 12a. The lubricating oil whose traveling direction has been changed collides with the intake-side recess 22a, merges with the flow of the cooling oil, and then flows through the intake-side recess 22a toward the intake-side skirt 12a. The cooling oil and the lubricating oil that merges with the cooling oil cooperate to cool the piston 10.

  As shown in FIG. 10, when the piston 10 moves upward by a predetermined distance from the oil flow direction conversion initial position, for example, when the piston 10 moves upward by 30 mm from the BDC, the nozzle tip of the lubricating nozzle 32 is oil. Since the facing direction of the surface of the flow direction conversion unit 31 is maintained, the traveling direction of the lubricating oil is changed by the oil flow direction conversion unit 31 and merges with the flow of the cooling oil, and the intake side recess 22a. To the intake side skirt portion 12a side.

  When the piston 10 moves upward from the oil flow direction change end position, the nozzle tip of the lubrication nozzle 32 is released from the opposing positional relationship with the surface of the oil flow direction change unit 31, and the piston 10 is cooled by the lubricating oil. finish. As shown in FIG. 7, the oil flow direction changing period Y is set to start in synchronization with the end of the lubricating oil supply period X and is longer than the lubricating oil supply period X. The piston 10 can be effectively used for cooling.

Next, the operation and effect of the oil supply device 1 will be described.
In this oil supply device 1, lubricating oil is supplied to the land portion 23 between the oil ring groove 26 and the second ring groove 25 only during a period in which the piston 10 is in the vicinity of the BDC (lubricating oil supply period X). Since the lubricating oil is not supplied except during the period near the BDC even during the ascending process, the optimal amount of lubricating oil that is sufficient to form the oil film on the inner peripheral surface of the cylinder bore 5 is determined with the oil ring groove 26 and the second ring. The sliding resistance of the piston 10 can be reduced while suppressing the supply of excess oil that can be supplied to the land portions 23 between the grooves 25 and is unnecessary for lubricating the piston 10.

  In addition, when the piston 10 moves upward from the position near the BDC (oil flow direction changing period Y), the oil flow direction changing portion 31 guides the lubricating oil to the intake side skirt portion 12a side. Thus, the cooling performance of the piston 10 can be increased. In addition, since the lubricating nozzle 32 and the piston 10 are improved in structure, the lubricating oil can be directly supplied from the tip of the nozzle to the oil guiding portion 30 formed in the pin boss portion 13. The structure can be simplified, and the manufacturing cost can be reduced.

Since the oil guide path 30 and the oil flow direction changing portion 31 are respectively formed in the pair of pin boss portions 13 and the plurality of oil supply passages 14 and 15 are communicated with the oil guide passage 30 of each pin boss portion 13. The oil amount can be efficiently supplied to the land portion 23 between the oil ring groove 26 and the second ring groove 25, and the sliding resistance of the piston 10 can be further reduced.
The oil guiding path 30 is formed in an inclined shape so as to move upward toward the center side of the piston 10, and the upper surface of the oil flow direction changing portion 31 extends so that the extended surface C intersects the axis B of the oil guiding path 30. Since it is formed in an inclined shape that moves to the skirt portion 12a side, the oil guiding portion 30 and the oil flow direction changing portion 31 can be formed without greatly changing the basic shape of the piston 10, and the manufacturing cost can be reduced. Can be cheap.

  It is arranged at the lower end portion of the cylinder bore 5 on the exhaust side skirt portion 12b side, and the cooling oil flows into the exhaust side recess portion 22b so that the cooling oil flows on the back surface 22 of the piston crown portion 11 from the exhaust side skirt portion 12b side to the intake side skirt portion 12a side. On the other hand, a cooling nozzle 35 for injecting cooling oil from below is provided, and the oil flow direction changing portion 31 is formed so that the direction-changed lubricating oil flows in the same direction as the cooling oil through the intake side recess portion 22a. Therefore, the cooling performance of the piston 10 is further enhanced by the synergistic effect of the lubricating oil and the cooling oil without hindering the flow of the cooling oil flowing through the back surface 22 of the piston crown portion 11. be able to.

An oil supply apparatus 1A according to the second embodiment will be described with reference to FIGS. In addition, about the member similar to Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.
The difference from the first embodiment is that, in the first embodiment, the oil guide path 30 is provided in the base portion 27 of the pin boss portion 13 and the oil flow direction changing portion 31 is provided in the pin receiving portion 28 of the pin boss portion 13. In the second embodiment, both the oil guiding path 30A and the oil flow direction changing portion 31A are provided on the base portion 27A of the pin boss portion 13A.

  Each of the pair of pin boss portions 13A includes a base portion 27A extending downward from the back surface 22, a pin receiving portion 28A formed at a lower portion of the base portion 27A, a pin hole 29 provided in the pin receiving portion 28A, and the like. . Each base portion 27A is formed with an oil guiding path 30A and an oil flow direction changing portion 31A. The oil guide path 30A is formed substantially parallel to the axis of the piston 10A, and is configured to extend in the vertical direction from the lower end portion of the base portion 27A to the piston crown portion 11 on the intake side skirt portion 12a side portion of the base portion 27A. Yes. Oil supply passages 14 and 15 are communicated with the upper end of the oil guide passage 30A, and a substantially circular opening 30b is formed at the lower end of the oil guide passage 30A so as to open directly downward.

  The oil flow direction changing portion 31A is formed from the lower end of the opening 30b of the oil guide passage 30A to the lower end of the pin receiving portion 28A on the intake side skirt portion 12a side. The surface of the oil flow direction changing portion 31A is formed in a substantially flat shape, and is formed in an inclined shape so as to move upward toward the intake side skirt portion 12a in a side view. As in the first embodiment, the oil flow direction changing period Y is started in synchronization with the end of the lubricating oil supply period X and is set to be longer than the lubricating oil supply period X. Thereby, the structure of the piston 10A can be further simplified while achieving the same effects as those of the first embodiment.

Next, a modification in which the above embodiment is partially changed will be described.
1) In the above embodiment, an example of a horizontally mounted four-cylinder engine has been described. However, at least a reciprocating engine may be used and applied to various internal combustion engine pistons such as a single cylinder engine, an engine having two or more cylinders, and a V-type engine. can do. It can also be applied to a vertical engine.

2) In the above embodiment, the example in which the lubricating oil supply period is started from the end of the piston lowering process, which is the previous stage of BDC, has been described. However, the lubricating oil supply period is only the initial period of the piston rising process from BDC. It may be set to. Thereby, the oil guiding path and the opening of the oil guiding path can be reduced in size.

3) In the above-described embodiment, the example in which the oil flow direction changing period is started in synchronization with the end of the lubricating oil supply period has been described. However, it is sufficient that the lubricating oil can be supplied to the land portion at least at a position near the BDC. The opening of the oil guide path and the oil flow direction conversion portion may be formed at a predetermined distance, and a time difference may be provided between the end of the lubricating oil supply period and the start of the oil flow direction conversion period. Further, although an example in which the oil flow direction conversion period is longer than the lubricating oil supply period has been described, the same period may be used, and the oil flow direction conversion period may be set shorter than the lubricating oil supply period.

4) In addition, those skilled in the art can implement the present invention in various forms added with various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

  The present invention relates to an oil supply device for a piston for an internal combustion engine that reciprocates in a cylinder bore, and an oil guide path that guides lubricating oil to a land portion when in the vicinity of the BDC, and lubrication when moving upward from the position near the BDC. By providing the oil flow direction changing portion for guiding the working oil to the one skirt portion side, it is possible to supply the lubricating oil amount optimal for forming the oil film to the land portion while simplifying the structure.

1, 1A Oil supply device 3 Crankshaft 4 Connecting rod 5 Cylinder bore 7 Oil injection device for lubrication 8 Oil injection device for cooling 10, 10A Piston 11 Piston crown portion 12a Intake side skirt portion 12b Exhaust side skirt portion 13, 13A Pin boss portion 14, 15 Oil supply path 22 (Piston crown part) Back face 23 Land part 25 Second ring groove 26 Oil ring grooves 30, 30A Oil guide paths 30a, 30b Openings 31, 31A Oil flow direction changing part 32 Lubrication nozzle 35 Cooling nozzle B (Oil Taxiway) axis
C (Oil flow direction changing part) Extension surface

Claims (4)

A piston crown portion, a pair of pin boss portions formed on the back surface of the piston crown portion and connected to a crankshaft via a connecting rod, and a pair of skirt portions extending downward from the piston crown portion, In an oil supply device for a piston for an internal combustion engine that reciprocates inside,
An oil guide path extending in the vertical direction to one skirt portion side portion of at least one pin boss portion and having an opening at a lower end;
An oil supply path having one end communicating with the upper end of the oil guide path and the other end communicating with a peripheral surface between the oil ring groove and the compression ring groove of the piston crown part;
When the piston is near the bottom dead center, the nozzle tip is arranged in an inclined shape so as to move upward toward the piston center so as to face the opening of the oil guide path, and injects lubricating oil into the opening. With possible nozzles for lubrication,
When the piston moves upward from a position near the bottom dead center to the lower part of the opening of the oil guide path, the lubricating oil sprayed from the lubricating nozzle is opposed to the nozzle tip, and the one skirt portion An oil supply device for a piston for an internal combustion engine, characterized in that an oil flow direction changing portion for guiding the oil flow direction is provided. The oil guiding path and the oil flow direction changing portion are respectively formed on the pair of pin boss portions,
The oil supply device for a piston for an internal combustion engine according to claim 1, wherein a plurality of oil supply passages are communicated with the oil guide passages of the pin boss portions.   The oil guiding path is formed in an inclined shape so as to move upward toward the piston center side, and the oil flow direction changing portion is inclined so as to move toward the one skirt portion side so as to intersect the axis of the oil guiding path. The oil supply device for a piston for an internal combustion engine according to claim 1 or 2, wherein It is disposed at the lower end of the cylinder bore on the other skirt portion side, and the cooling oil flows from below to the back surface of the piston crown portion so that the cooling oil flows from the other skirt portion side to the one skirt portion side. A cooling nozzle for injecting cooling oil is provided,
4. The oil flow direction changing portion according to claim 1, wherein the direction-converted lubricating oil flows in the same direction as the cooling oil on the back surface of the piston crown portion. An oil supply device for a piston for an internal combustion engine according to claim 1.