JP2008297928A - Piston of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston of internal combustion engine that can achieve both of oil retention performance and removal performance of foreign substances. <P>SOLUTION: On a surface 4a of a skirt 4 of a piston 1, stripe traces 9 (traces remained in the form of stripes) are formed so as to extend obliquely relative to a sliding direction of the piston 1 as shown by an arrow A. Since the stripe traces 9 are formed so as to extend obliquely relative to the sliding direction shown by the arrow A, they can prevent abnormal friction and seizing due to oil retention, which is the purpose for providing the stripe traces, that is, can perform a lubrication action. In addition, even if foreign substances have been caught between peripheral surface of the piston 1 and cylinder bore surface 2a, the foreign substances can be moved in the sliding direction of the piston 1 along the stripe traces 9. Therefore, removal performance of foreign substances in the peripheral surface of the piston 1 can be enhanced, thus achieving both oil retention performance and removal performance of foreign substances. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piston for an internal combustion engine.

  A piston used in an internal combustion engine is connected to a crankshaft via a connecting rod, and generates a shaft output in the crankshaft by sliding up and down in a cylinder bore. Generally, this piston is provided with a skirt portion that mainly suppresses rolling and releases heat to the cylinder. The skirt portion of the piston slides up and down while in contact with the cylinder bore surface during the combustion stroke. For this reason, conventionally, various measures have been taken to prevent abnormal friction and seizure during sliding.

For example, as shown in Patent Literature 1 and Patent Literature 2, in order to improve the oil retaining property of the skirt portion, the streak (the trace that remains as a streak) in the direction orthogonal to the piston sliding direction is removed from the skirt. It is intended to be formed on the surface of the part. This is intended to prevent abnormal friction and seizure by holding oil in the streak and constantly supplying oil to the sliding surface.
JP 2000-88101 A JP 2006-16982 A

  By the way, when there is a streak in the direction perpendicular to the piston sliding direction as described above, the oil is easily held by the streak, but the foreign matter caught between the skirt and the cylinder bore surface is also streak. It becomes easy to be held by the marks. For this reason, the foreign matter once bitten repeatedly slides together with the piston, causing a sliding in the sliding direction on the cylinder bore surface.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a piston for an internal combustion engine that can achieve both oil retention and foreign matter removal.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, in the piston of the internal combustion engine having a plurality of oil retaining streaks on the outer peripheral surface, the striations are formed to extend obliquely with respect to the sliding direction of the piston. Is the gist.

  According to the above configuration, since the streak is formed to extend obliquely with respect to the sliding direction, the purpose of providing the streak is to prevent abnormal friction and seizure due to oil retention, that is, a lubricating action. Can do. Further, even if foreign matter is caught between the piston outer peripheral surface and the bore, the foreign matter can be moved in the sliding direction of the piston along the streak, so that the foreign matter removability on the piston outer peripheral surface is improved. be able to. Accordingly, both oil retention and foreign matter removal can be achieved.

  Specifically, as described in claim 2, the pitch of the streak is about 0.1 to 0.3 mm, and the depth of the streak is about 0.005 to 0.03 mm. Aspects can be employed.

  The invention according to claim 3 is characterized in that, in the piston of the internal combustion engine according to claim 1 or 2, the piston has a skirt portion, and the streak is formed in the skirt portion.

  According to the above configuration, the striations are formed in the skirt portion that slides up and down while in contact with the cylinder bore surface in the combustion stroke, which is advantageous in suppressing abnormal friction and seizure during sliding.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described with reference to FIGS.
FIG. 1 shows a front view of the piston 1 according to this embodiment, and FIG. 2 shows a side view of the piston 1 according to this embodiment. The piston 1 is inserted into a cylinder bore 2 formed in the cylinder block 10 and slides up and down on the cylinder bore surface 2a in the direction indicated by the arrow A. A cylinder head 11 is provided on the upper portion of the cylinder block 10.

  The piston 1 has a top land 5, a second land 6, and a third land 7 formed at the upper portion, and a skirt portion 4 formed at the lower portion. Piston rings 3 are attached to the grooves between the top land 5, the second land 6, and the third land 7, respectively. Further, a piston pin boss 8 is formed so as to penetrate in the diameter direction of the piston 1. A piston pin (not shown) is inserted into the piston pin boss 8.

  The skirt portion 4 has a streak 9 (a trace remaining as a streak) formed on the surface 4a thereof. The streak 9 is formed to extend obliquely with respect to the sliding direction of the piston 1 indicated by the arrow A. Here, the angle of the stripe 9 with respect to the sliding direction of the piston 1 is set to be, for example, 30 to 60 °. In the present embodiment, streaks 9 are also formed on the surface of the portion between the third land 7 and the skirt portion 4. Specifically, as shown in the cross-sectional view of FIG. 3, the streak 9 is formed so that the pitch P is about 0.1 to 0.3 mm and the depth W is about 0.005 to 0.03 mm. Is formed. The streak 9 is formed by, for example, turning with a cutting tool or rolling with a roller.

According to this embodiment described above, the following effects can be obtained.
(1) Since the streak 9 is formed so as to extend obliquely with respect to the sliding direction, the object of providing the streak 9 is to prevent abnormal friction and seizure due to oil retention, that is, a lubricating action. . Further, as shown in FIG. 4, even if foreign matter is caught between the outer peripheral surface of the piston 1 and the cylinder bore surface 2 a, the foreign matter can be moved along the streak 9 in the sliding direction of the piston 1. . Specifically, as shown in FIG. 4A, when the piston 1 slides in the direction indicated by the arrow A1, the foreign matter moves along the streak 9 in the direction indicated by the arrow B1. On the contrary, as shown in FIG. 4B, when the piston 1 slides in the direction indicated by the arrow A2, the foreign matter moves along the streak 9 in the direction indicated by the arrow B2. Therefore, since the removal property of the foreign material on the outer peripheral surface of the piston 1 can be improved, both the oil retention property and the foreign material removal property can be achieved.

  On the other hand, conventionally, as shown in FIGS. 5 and 6, the streak 39 is formed on the surface 34 a of the skirt portion 34 so as to extend in a direction perpendicular to the sliding direction indicated by the arrow A <b> 3. In this case, when a foreign object is caught between the outer peripheral surface of the piston 31 and the cylinder bore surface 32a, the streak 39 becomes a resistance, so that it is difficult for the foreign object to move in the sliding direction of the piston 31 indicated by the arrow A3. is there. For this reason, the foreign matter once bitten repeatedly slides together with the piston 31 and causes damage to the cylinder bore surface 32a in the sliding direction.

(2) Since the streak 9 is formed in the skirt portion 4 that slides up and down while contacting the cylinder bore surface 2a in the combustion stroke, it is advantageous in suppressing abnormal friction and seizure during sliding.
(Other embodiments)
In addition, the piston of the internal combustion engine according to the present invention is not limited to the configuration exemplified in the above-described embodiment, and can be implemented as, for example, the following form obtained by appropriately modifying the embodiment.

  -In above-mentioned embodiment, piston 1 of the internal combustion engine which provided the streak 9 in the skirt part 4 of piston 1 was illustrated. However, as shown in FIG. 7, it is possible to adopt a mode in which the striations 29 are also formed on the top land 25, the second land 26, and the third land 27 above the piston 21. Even in this case, the above effects (1) and (2) can be achieved.

  The streak is not limited as long as it retains oil during normal operation of the internal combustion engine, and its position, width, pitch, and depth are arbitrarily determined based on actual machine tests and the like within the scope of the above. Can do.

The front view which shows typically the piston of the internal combustion engine concerning this invention. The side view which shows typically the piston of the internal combustion engine concerning this invention. The expanded sectional view of the surface of the skirt part of FIG. (A), (b) The enlarged view of the surface of the skirt part of FIG. The front view which shows typically the piston of the conventional internal combustion engine. The enlarged view of the surface of the skirt part of FIG. The front view which shows typically the modification of the piston of the internal combustion engine concerning this invention.

Explanation of symbols

  1, 2, 31 ... Piston, 2, 22, 32 ... Cylinder bore, 3 ... Piston ring, 4, 24, 34 ... Skirt, 5, 25 ... Top land, 6, 26 ... Second land, 7, 27 ... Third land , 8 ... piston pin boss, 9, 29, 39 ... streak, 10 ... cylinder block, 11 ... cylinder head.

Claims (3)

In the piston of the internal combustion engine having a plurality of streaks for retaining oil on the outer peripheral surface,
The said striation is formed so that it may extend diagonally with respect to the sliding direction of a piston. The piston characterized by the above-mentioned. In claim 1,
The pitch of the streak is about 0.1 to 0.3 mm,
The piston of the internal combustion engine, wherein the depth of the streak is approximately 0.005 to 0.03 mm. In claim 1 or 2,
The piston has a skirt;
The said streak is formed in the said skirt part. Piston of the internal combustion engine characterized by the above-mentioned.

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