JP2010164012A - Piston for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston for an internal combustion engine which can secure reduction of consumption of engine oil and highly maintain rigidity of piston without adding reinforcement such as thickening of component parts. <P>SOLUTION: The piston for the internal combustion engine is integrally equipped with: a substantially covered cylindrical crown portion 12 having oil ring grooves 11; skirt portions 13 protruding to face each other from part of the lower edge of the crown portion 12; piston pin bosses 14 formed on an axis orthogonal to an axis of the crown portion 12 to support a piston pin; and skirt ribs 15 formed to face each other between the skirt portions 13 and piston pin bosses 14, intersecting with the skirt portion 13. In the oil ring grooves 11, a plurality of oil escape holes 16 and 17 are formed which communicate inside and outside the crown portion 12, and at least one hole of the oil escape holes has a smaller diameter than other holes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piston for an internal combustion engine mounted on an internal combustion engine such as a vehicle engine, and more particularly, to a piston for an internal combustion engine provided with an oil relief hole when engine oil on a cylinder inner peripheral surface is scraped off by an oil ring.

  Conventionally, in an internal combustion engine piston mounted on an internal combustion engine such as a vehicle engine, a plurality of piston ring grooves that are formed on the outer periphery of a substantially cylindrical piston and open outwardly, from the top surface of the piston. An oil ring is fitted in an oil ring groove formed at the most spaced position.

  The oil ring groove is formed with an oil relief slit at the bottom of the oil ring groove facing the open end. When the piston is lowered as a combustion cycle of the internal combustion engine, the oil ring groove is scraped off by the oil ring. The internal combustion engine is configured so that the engine oil on the peripheral surface is released to the inside of the piston to prevent the engine oil from being led to the combustion chamber and combusted with the air-fuel mixture, and to reduce the amount of engine oil consumed by the combustion. 2. Description of the Related Art Engine pistons (hereinafter simply referred to as “pistons” in some cases) are known (see, for example, Patent Document 1).

  However, in the internal combustion engine piston configured as described above, in order to reduce the slap noise caused by the piston side pressure during combustion, an oil relief slit is formed at the bottom of the oil ring groove on the thrust side, thereby reducing the rigidity of the piston. There has been a problem of significantly lowering.

  Therefore, in order to ensure the rigidity of the piston, it is necessary to increase the thickness of the piston crown and to take measures to reinforce the piston pin boss.As a result, the piston weight increases, resulting in a high rotation / high output internal combustion engine. Will be unsuitable.

  In particular, in such a piston, since the slit is formed on the thrust side on which the side pressure acts, the influence of the lowering of rigidity is more greatly affected.

  In addition, reinforcement such as thickening to compensate for insufficient rigidity on the thrust side causes the piston's center of gravity to be offset from the center of the piston to the thrust side, resulting in problems such as imbalance in rigidity, which increases piston side pressure. There was a risk of doing so.

Japanese Utility Model Publication No. 06-014454

  Therefore, the present invention takes into consideration the above-mentioned circumstances, and can ensure high piston rigidity without taking reinforcement measures such as thickening the component parts while ensuring reduction in consumption of engine oil. The purpose is to provide.

  The piston for an internal combustion engine of the present invention protrudes so as to face each other from a substantially covered cylindrical crown portion having one or more piston ring grooves opened in the outer circumferential direction and a part of a lower edge portion of the crown portion. The skirt portion, the piston pin boss formed on an axis perpendicular to the axis of the crown portion and supporting the piston pin, and the skirt portion and the piston pin boss facing each other so as to be perpendicular to the skirt portion. In the piston for an internal combustion engine that is integrally provided with the skirt rib formed as described above, an oil ring groove provided at a position farthest from the top surface of the crown portion among the plurality of piston rings is provided with an inner and outer portion of the crown portion. A plurality of oil relief holes formed to communicate with each other, and at least one hole diameter of the plurality of oil relief holes Characterized in that it has a smaller diameter than the diameter of the oil escape holes.

  According to the piston for an internal combustion engine of the present invention, it is possible to maintain a high piston rigidity without taking measures for reinforcement such as thickening of components while ensuring a reduction in consumption of engine oil.

  The piston for an internal combustion engine according to claim 2, wherein at least one oil relief hole having a small diameter is disposed at a position deviated in the circumferential direction from a position where a thrust load applied from the cylinder to the piston is largely applied. It is characterized by that.

  According to the piston for an internal combustion engine according to claim 2, the amount of oil escaping from an oil escaping hole formed in the vicinity of a portion where a thrust load from the cylinder to the piston acts greatly can be increased, and the oil consumption can be made efficient. It can be reduced well.

  The piston for an internal combustion engine according to claim 3 is characterized in that at least one oil relief hole having a small diameter is disposed at a position away from the skirt portion in the circumferential direction.

  According to the piston for an internal combustion engine according to claim 3, the oil relief hole formed in the portion where the rigidity is not relatively high due to the skirt portion not being formed is made a small diameter, whereby the piston A decrease in rigidity can be suppressed.

  The piston for an internal combustion engine according to claim 4 is characterized in that the plurality of oil relief holes are formed to extend from the groove bottom portion facing the open end of the oil ring groove to the groove lower surface.

  According to the piston for an internal combustion engine of the fourth aspect, it is possible to increase the oil escape amount while suppressing the oil rise when the piston is lowered.

  6. The piston for an internal combustion engine according to claim 5, wherein at least one of the plurality of oil relief holes having a large diameter is a thick wall near a root where the skirt rib is connected to the inner wall of the skirt portion. It is formed in the part.

  According to the piston for an internal combustion engine according to claim 5, it is possible to suppress a decrease in piston rigidity by forming a large-diameter oil relief hole in the thick portion near the base of the skirt rib which is easy to ensure high rigidity. .

  The piston for an internal combustion engine according to claim 6, wherein a plurality of oil relief holes having a large diameter are defined by a specific region inside the piston that is partitioned by the skirt portion and the skirt rib. It is arrange | positioned so that it may open inside.

  According to the piston for an internal combustion engine according to claim 6, a large amount of engine oil discharged from the large-diameter oil escape hole to the inside of the piston can be attached to the skirt rib, and the piston pin and the piston can be formed using the engine oil. Lubrication performance at the sliding contact portion with the pin boss can be improved.

  The piston for an internal combustion engine of the present invention can maintain high piston rigidity without taking measures for reinforcing the component parts, such as increasing the thickness, while ensuring a reduction in consumption of engine oil.

It is a perspective view from the plane direction of the piston for internal combustion engines which concerns on one Embodiment of this invention. 1 is a side view of a piston for an internal combustion engine according to an embodiment of the present invention. It is a perspective view from the bottom face direction of the piston for internal combustion engines which concerns on one Embodiment of this invention. It is sectional drawing which follows the AA line of FIG. 2 in the piston for internal combustion engines which concerns on one Embodiment of this invention. It is sectional drawing which follows the BB line of FIG. 2 in the piston for internal combustion engines which concerns on one Embodiment of this invention.

  Next, a piston for an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. One embodiment shown below is a preferred specific example of the piston for an internal combustion engine of the present invention, and may have various technically preferable limitations, but the technical scope of the present invention is particularly limited. As long as there is no description which limits this invention, it is not limited to these aspects.

  FIG. 1 is a perspective view of a piston for an internal combustion engine according to an embodiment of the present invention in a planar direction, FIG. 2 is a side view of the piston for an internal combustion engine according to an embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view taken along line AA of FIG. 2 in the piston for an internal combustion engine according to one embodiment of the present invention, and FIG. 5 relates to the present invention. It is sectional drawing which follows the BB line of FIG. 2 in the piston for internal combustion engines of one Embodiment.

  As shown in the drawing, an internal combustion engine piston 10 according to an embodiment of the present invention is inserted into a cylinder of an internal combustion engine (not shown) and reciprocates in the cylinder while being in sliding contact with the inner peripheral surface thereof. A combustion chamber is defined in the upper part, and is integrally formed in a substantially covered cylindrical shape from an aluminum alloy material or the like. The piston 10 for the internal combustion engine is opposed to each other from a substantially covered cylindrical crown portion 12 having one or more piston ring grooves 11 opened in the outer circumferential direction and a part of a lower edge portion of the crown portion 12. The projecting skirt 13, the piston pin boss 14 that is formed on the axis orthogonal to the axis of the crown 12 (in other words, the axis of the cylinder not shown) and supports the piston pin (not shown), and the skirt 13 And a skirt rib 15 formed so as to face each other between the skirt portion 13 and the piston pin boss 14 so as to be orthogonal to each other (in other words, orthogonal to the axis of the piston pin not shown).

  A plurality of piston ring grooves 11 are formed over the entire outer wall surface of the crown portion 12 (for example, three levels up and down), and the three-stage piston ring grooves 11 are top in order of increasing distance from the top surface of the crown portion 12. A ring groove 11A, a second ring groove 11B, and an oil ring groove 11C are formed. A compression ring (not shown) is attached to each of the top ring groove 11A and the second ring groove 11B to maintain the airtightness of the combustion chamber, and an oil ring 18 (shown in FIG. 4) is attached to the oil ring groove 11C. It plays the role of scraping off the oil on the inner wall surface of the cylinder. A plurality of oil relief holes 16 and 17 are formed in the oil ring groove 11C so as to communicate with the inside and outside of the crown portion 12, and the oil that has been scraped off by the oil ring 18 and collected in the oil ring groove 11C. Is discharged inside the piston 10 for the internal combustion engine. Note that the top ring groove 11A and the second ring groove 11B can be set to a number, interval, or the like in consideration of the output thereof, and is not particularly limited with respect to the implementation of the present invention.

  The plurality of oil relief holes 16, 17 penetrate the crown portion 12 so as to extend radially from the center of the crown portion 12. The plurality of oil relief holes 16 and 17 are set such that the diameter of the oil relief hole 16 is smaller than the diameter of the oil relief hole 17.

  The oil relief holes 16 are disposed between the skirt rib 15 and the boss rib 19 (for example, one each). In other words, the oil relief hole 16 is disposed at a position that deviates in the circumferential direction from the vicinity where the thrust load (piston side pressure) from the cylinder to the piston is largely applied. Specifically, from the range where the skirt portion 13 is formed. It is placed at a position that is off. The crown portion 12 at a position away from the skirt portion 13 has a relatively low rigidity with respect to the crown portion 12 within the formation range of the skirt portion 13, but the strength of the crown portion 12 can be increased by reducing the hole diameter. While ensuring, the oil escape effect is secured. Further, since the oil escape hole 16 is formed within a range surrounded by the skirt rib 15 and the boss rib 19 for increasing the rigidity of the crown portion 12, the strength is further reduced due to the small diameter. This can be further prevented.

  Here, the boss ribs 19 are reinforcing ribs that connect the outer end portion of the piston pin boss 14 and the lower end portion of the crown portion 12. Two boss ribs 19 are provided on each piston pin boss 14 and provided at a total of four locations. It has been. Each piston pin boss 14 has a piston pin support hole 14a, and one end of a connecting rod (not shown) is connected to the piston pin supported between the piston pin support holes 14a. When the top surface of the portion 12 is bent downward, the piston pin boss 14 is deformed so as to fall outward. Therefore, the boss rib 19 is provided to prevent the piston pin boss 14 from being deformed.

  The oil relief holes 17 are arranged (for example, three locations) between the pair of skirt ribs 15. In other words, the oil relief holes 17 are arranged side by side in the circumferential direction in the vicinity where the above-described thrust load is large. However, since the skirt portion 13 is formed in this part, the rigidity is originally high and the hole diameter is set large. Even so, the strength of the crown portion 12 is not impaired, and the oil escape effect can be increased by increasing the hole diameter. At this time, the large-diameter oil relief hole 17 is formed, for example, by forming two oil relief holes 17 disposed at both ends of the oil relief hole 17 in a thick portion near the root of the skirt rib 15 so that the vicinity of the root is the crown portion. Since it is easy to ensure the thickness in 12 (filling), even if a large-diameter through hole is formed, it is possible to easily ensure high rigidity.

  Note that the number and diameter of the oil relief holes 16 and 17 are determined based on the diameter of the crown portion 12 determined in consideration of, for example, the output of the internal combustion engine (including the number of cylinders). In this embodiment, the crown portion 12 has a diameter of 74.5 mm, the oil escape hole 16 has a diameter of 2.0 mm, and the oil escape hole 17 has a diameter of 2.4 mm.

  At this time, the hole diameters of the oil release holes 16 and 17 are obtained when the ratio (for example, 6: 4) is obtained in advance, and the hole diameter of one of the oil release holes 16 and 17 is determined according to the output of the internal combustion engine. May be configured such that the diameter of the other oil relief holes 16, 17 can also be determined.

  Accordingly, the middle oil relief hole 17 formed near the middle of the pair of skirt ribs 15 is between the diameter of the other large oil relief hole 17 and the diameter of the small oil relief hole 16 (for example, 6 : 5: 4), or specified by a relative opening area or the like.

  The crown portion 12 has a top shape that is determined to be substantially flat, substantially chevron-shaped, or different, depending on the combustion cycle such as the supply / exhaust structure in the combustion chamber and output (power).

  The skirt portion 13 is formed in a thin vertical wall shape that is curved in a range of about 50% as a whole of the pair of skirt portions 13 with respect to the entire circumference of the crown portion 12. The shape of the skirt portion 13 is not particularly limited with respect to the implementation of the present invention.

  In the above configuration, the internal combustion engine piston 10 in the combustion cycle scrapes off the engine oil when the piston is lowered. That is, the oil ring 18 adheres to the upper surface of the oil ring groove 11C (the surface facing the groove lower surface 11b) during the descending cycle to prevent the engine oil from rising (intruding) into the combustion chamber, and in the combustion chamber. It is possible to suppress unnecessary combustion (consumption) of oil.

  Further, the scraped engine oil can be guided (released) to the inside of the piston 10 for the internal combustion engine via the oil relief holes 16 and 17.

  At this time, it is preferable that the oil relief holes 16 and 17 ensure strength without increasing the thickness of the crown portion 12 while securing the escape amount. If a large area is secured, the oil escape amount increases, but the strength becomes difficult to secure. If the oil relief holes 16 and 17 are formed larger than the groove width (groove height) of the oil ring groove 11C, the upper surface of the oil ring groove 11C is moved by the oil ring 18 when the piston 10 for the internal combustion engine is lowered. The oil relief holes 16 and 17 in the vicinity will be blocked, and it will be substantially difficult to increase the amount of oil relief.

  Therefore, the plurality of oil relief holes 16 and 17 of the present invention make it easy to ensure the strength of the crown portion 12, and the hole diameters are made different according to the distance from the pressure receiving surface of the side pressure during the combustion cycle, and the oil ring By forming the groove 11C across the groove lower surface 11b from the groove bottom portion 11a facing the open end of the groove 11C, it is possible to ensure the oil escape amount and the strength.

  Thus, in the piston 10 for an internal combustion engine of the present invention, the oil ring groove 11C is formed with a plurality of oil relief holes 16, 17 communicating with the inside and outside of the crown portion 12, and the plurality of oil relief holes 16 are formed. , 17, the diameter of the oil relief hole 16 is smaller than the diameter of the other oil relief holes 17, and the reinforcement measures such as thickening of the component parts are taken while ensuring the reduction in the consumption of engine oil. The piston rigidity can be kept high without any problems.

  At this time, the oil relief hole 16 having a small hole diameter is formed at a position deviated in the circumferential direction from the vicinity where the thrust load to the piston acts greatly, so that it is formed near the portion where the thrust load acts greatly. In addition, the amount of oil escaping from the large-diameter oil escaping hole 17 can be increased, and the amount of oil consumption can be efficiently reduced.

  Further, the oil relief hole 16 having a small diameter is disposed at a position deviated from the skirt portion 13 in the circumferential direction, so that it is difficult to ensure high rigidity due to the absence of the skirt portion 13. The oil relief hole 16 having a small diameter can be positioned at the bottom, and a reduction in rigidity of the piston 10 for the internal combustion engine can be suppressed.

  The plurality of oil relief holes 16 and 17 are formed across the groove bottom surface 11a facing the open end of the oil ring groove 11C and the groove lower surface 11b, so that the piston 10 for the internal combustion engine descends in the combustion cycle. The oil escape amount can be increased while suppressing the engine oil from rising at the time.

  Furthermore, at least one of the plurality of oil relief holes 16 and 17 having a large diameter is formed in a thick portion near the base of the skirt rib 15 that connects the piston pin boss 14 and the inner wall of the skirt portion 13. Therefore, the rigidity reduction of the piston 10 for the internal combustion engine can be suppressed by forming the large-diameter oil relief hole 17 in the thick wall portion near the base of the skirt rib 15 that easily secures high rigidity.

  Moreover, all of the large oil relief holes 17 other than the oil escape hole 16 having a small diameter among the plurality of oil relief holes 16 and 17 are arranged inside the piston defined by the skirt portion 13 and the skirt rib 15. As a result, a large amount of engine oil discharged from the large-diameter oil relief hole 17 to the inside of the piston can be attached to the skirt rib 15, and the sliding contact between the piston pin and the piston pin boss 14 using the engine oil. Lubrication performance at the site can be improved.

DESCRIPTION OF SYMBOLS 10 ... Piston for internal combustion engines 11 ... Piston ring groove 11A ... Top ring 11B ... Second ring 11C ... Oil ring 12 ... Crown part 13 ... Skirt part 14 ... Piston pin boss 15 ... Skirt rib 16 ... Oil relief hole (small diameter)
17 ... Oil relief hole (large diameter)
18 ... Oil ring

Claims (6)

A substantially covered cylindrical crown portion having one or more piston ring grooves opened in the outer circumferential direction; a skirt portion projecting from a part of a lower edge portion of the crown portion; A piston pin boss formed on an axis orthogonal to the axis and supporting the piston pin, and a skirt rib formed to face each other between the skirt portion and the piston pin boss so as to be orthogonal to the skirt portion; In a piston for an internal combustion engine that is integrally provided with
Among the plurality of piston rings, an oil ring groove provided at a position most distant from the top surface of the crown portion includes a plurality of oil relief holes formed so as to communicate with the inside and outside of the crown portion. A piston for an internal combustion engine, characterized in that at least one hole diameter of the oil relief hole is smaller than the diameters of the other oil relief holes.   2. The internal combustion engine according to claim 1, wherein the at least one oil relief hole having a small diameter is disposed at a position deviated in a circumferential direction from a position where a thrust load applied from the cylinder to the piston acts greatly. Piston for engine.   3. The piston for an internal combustion engine according to claim 1, wherein at least one oil escape hole having a small diameter is disposed at a position deviated in a circumferential direction from the skirt portion. 4.   The internal combustion engine according to any one of claims 1 to 3, wherein the plurality of oil relief holes are formed from a groove bottom facing the open end of the oil ring groove to a groove lower surface. Piston.   The at least one of the plurality of oil relief holes having a larger diameter is formed in a thick part near a base where the skirt rib is connected to an inner wall of the skirt part. The piston for an internal combustion engine according to any one of claims 1 to 4.   Among the plurality of oil relief holes, those having a large diameter are arranged so that all of them are opened in a specific region inside the piston defined by the skirt portion and the skirt rib. 6. A piston for an internal combustion engine according to claim 5,

Images