JP2013209963A - Piston structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston structure capable of preventing deterioration in oil consumption, by excellently holding a horizontal state of an oil ring, even when a piston pin hole and an oil ring groove are formed in close vicinity to each other.SOLUTION: In an eaves part 10 of separating an oil ring groove 4 and a piston pin hole 6 of a piston 1 for forming compression ring grooves 2 and the oil ring groove 4 in order from above the outer periphery, a vertical groove 12 is formed in a position where the oil ring groove 4 and the piston pin hole 6 are in closest vicinity to each other. This vertical groove 12 reaches the same depth as a side peripheral wall surface 4a of the oil ring groove 4. An interval between the lowest surface 4b of the oil ring groove 4 and the uppermost surface 6a of the piston pin hole 6 is smaller than a thickness dimension of a partition wall 8 for separating the oil ring groove 4 and the compression ring groove 2.

Description

  The present invention relates to a structure of a piston for an internal combustion engine that suppresses oil rising.

  In general, an appropriate number of compression rings are provided on the outer peripheral surface of an engine piston, and an oil ring is mounted below the compression ring. And the small end part of a connecting rod is connected with the piston pin hole formed further downward using the piston pin.

  By the way, in the same series of engines with different displacements, a cylinder block is often used in common. In this case, the compression height is changed by changing the attachment position of the connecting rod with respect to the piston in either direction of reciprocation, and the exhaust amount is adjusted. Thereby, cost reduction becomes possible.

  As described above, when the position of the piston pin hole is changed in the reciprocating direction, the distance between the piston pin hole and the oil ring groove becomes closer in the piston with the smaller displacement. FIG. 6 shows the structure of a piston with a small displacement.

  Referring to FIG. 6, two compression ring grooves 102, one oil ring groove 104, and a piston pin hole 106 are formed on the outer periphery of the piston 101 in order from the top. In the configuration example shown in FIG. 6, since the oil ring groove 104 and the piston pin hole 106 are formed close to each other, both of the eaves portions 110 that separate the oil ring groove 104 and the piston pin hole 106 are The lower side of the closest position is scraped off to form a thin portion 110a. Such a piston structure is disclosed in, for example, Patent Document 1.

  In this way, engine displacement is provided by adjusting the displacement of the cylinder block in common. As for the relationship between the piston pin hole and the oil ring groove, the relationship as in Patent Document 1 has already been disclosed. In Patent Document 1, a part of the eaves portion referred to in the present invention is removed.

Japanese Utility Model Publication No. 2-37249

  However, when the outer periphery of the piston 101 shown in FIG. 6 is processed, undulation may occur in the thin portion 110a. That is, in general, in the piston processing step, piston pin hole processing is first performed, and then outer periphery processing for forming a compression ring groove, an oil ring groove, etc. is performed. Since the lower side of the eaves portion close to the piston pin hole is cut off, the rigidity is insufficient and undulation is likely to occur.

  And when a wave | undulation arises in an eaves part in this way, a plane cannot be hold | maintained at the lower surface of an oil ring groove | channel, and there exists a possibility that oil consumption may increase. Moreover, the piston structure of patent document 1 solves the problem of oil rising, and does not mention the strength of the eaves part.

  Therefore, the present invention provides a piston structure that can maintain the horizontal state of the oil ring well and prevent deterioration of oil consumption even when the piston pin hole and the oil ring groove are formed close to each other. The purpose is to do.

In order to achieve the above object, in the piston structure of the present invention,
A piston structure in which a compression ring groove, an oil ring groove, and a piston pin hole are formed in order,
The distance between the uppermost surface of the piston pin hole and the lowermost surface of the oil ring groove is smaller than the thickness of the partition wall that separates the compression ring groove and the oil ring groove,
In the eaves part separating the oil ring groove and the piston pin hole,
At a depth reaching the side wall surface of the oil ring groove,
Including the closest position of the oil ring groove and the piston pin hole;
A groove portion that divides the eaves portion in the circumferential direction is formed.

  Further, the piston structure is characterized in that an end portion of the eaves portion forming the groove portion has an R shape, and the groove portion has a narrower opening width in the piston downward direction than an opening width in the piston upward direction.

  As described above, according to the present invention, even when the interval between the oil ring groove and the piston pin hole is smaller than the thickness of the partition wall between the oil ring groove and the compression ring groove, A groove portion is formed at the closest position, and the eaves portion is formed to have a predetermined thickness or more. Thereby, it is possible to prevent the eaves portion from being swelled during the processing of the outer peripheral surface of the piston, so that the processing becomes easy and the increase in oil consumption due to the swell can be prevented.

  Furthermore, since oil can be dropped through the groove, it is not necessary to provide an oil drop hole separately, and cost can be reduced.

  In addition, when the vertical groove is formed in the oil ring groove, there is a possibility that the side rail joint of the oil ring may be caught in the vertical groove. However, in the present invention, the end portion of the eave portion that forms the groove portion is defined as R. Since the shape and the groove opening width on the upper side of the groove portion are made wider than the lower opening width, there is an effect that even if the side rail opening of the oil ring comes into the groove portion, it is difficult to catch.

It is the perspective view which showed the structure of the piston which concerns on embodiment of this invention. 1 shows the periphery of the oil ring groove with respect to the AA cross section of the piston of FIG. 1, (a) shows a state when the piston is raised, and (b) shows a state when the piston is lowered. . It is the sectional view on the AA line of FIG. It is a front view of the piston of FIG. FIG. 5 is a partially enlarged view of FIG. 4. It is the perspective view which showed the structure of the conventional piston.

  Hereinafter, embodiments of the piston structure of the present invention will be described with reference to the drawings.

  FIG. 1 shows a piston 1 according to an embodiment of the present invention. As can be seen from this figure, two compression ring grooves 2 and an oil ring groove 4 are formed on the outer periphery of the piston 1 in order from above. A piston pin hole 6 is formed adjacent to the lower portion of the oil ring groove 4. In the piston 1 according to the present embodiment, the oil ring groove 4 and the piston pin hole 6 are formed closer to the thickness of the partition wall 8 that separates the compression ring groove 2 and the oil ring groove 4.

  The eaves portion 10 at the closest position between the oil ring groove 4 and the piston pin hole 6 is partially cut away to form a vertical groove 12 (groove portion). Further, the vertical groove 12 reaches the depth of the side peripheral wall surface 4 a of the oil ring groove 4. Thus, since a part of the eaves part 10 to which the piston pin hole 6 is adjacent is deleted, it can be avoided that the eaves part 10 becomes thinner as the thickness becomes insufficient.

  In order to employ such a shape, first, the longitudinal groove 12 is formed at the stage of the casting process of the piston 1. As a result, when the outer peripheral machining such as the compression ring groove 2 or the oil ring groove 4 is performed, there is no thin portion that causes undulation, the machining is facilitated, and the flatness of the surface on which the oil ring is placed is improved. It becomes possible to keep it good.

  Next, the positional relationship between the piston 1 and the inner wall of the cylinder will be described with reference to FIG. FIG. 2 is an enlarged view of the periphery of the oil ring 24 of the piston 1 cut along the line AA in FIG. 1 and shows a state when the piston 1 is sliding with respect to the inner wall 30 of the cylinder. 2A shows a state when the piston 1 is raised, and FIG. 2B shows a state when the piston 1 is lowered.

  First, referring to FIG. 2A, oil adhering to the upper side of the inner wall 30 of the cylinder is scraped off by the oil ring 24. The scraped oil falls downward from the upper surface of the oil ring 24 along the side wall surface 4 a of the oil ring groove 4. At this time, at the position where the vertical groove 12 is formed, it can fall down as it is, and the oil scraped off at other positions can also be collected in the vertical groove 12 and fall down.

  Next, referring to FIG. 2 (b), the oil adhering to the lower side of the inner wall 30 of the cylinder is scraped off by the oil ring 24. The scraped oil 32 passes from the inside of the oil ring 24 toward the side wall surface 4a of the oil ring groove 4 and falls downward, and also falls downward from the lower surface of the oil ring 24. As in the case where the piston 1 is lifted, the oil 32 that has been scraped off can be dropped as it is at the position where the longitudinal groove 12 is formed, and the oil 32 that has been scraped off at other positions can also be removed. It can be collected in the groove 12 and fall downward.

  Thus, according to the structure of the piston 1 of the present invention, since the vertical groove 12 plays the role of the conventional oil pit, it is not necessary to separately form an oil pit, and the process can be reduced, resulting in cost reduction. Can contribute.

  As described above, the longitudinal groove 12 as described above is useful when the oil ring groove 4 and the piston pin hole 6 are formed close to each other. Next, FIG. It explains using.

  FIG. 3 is a cross-sectional view of the piston 1 of FIG. 1 taken along the line AA, and shows the upper side of the piston pin hole 6 in an enlarged manner.

  As can be seen from FIG. 3, the dimension t3 between the uppermost surface 6a of the piston pin hole 6 and the lowermost surface 4b of the oil ring groove 4 is such that the partition wall 8 separating the compression ring groove 2 and the oil ring groove 4 on the lower side is separated. It is smaller than the thickness dimension t1. The longitudinal groove 12 according to the present invention is useful for the piston 1 having a relationship of at least t1> t3.

  In addition, this effect becomes more remarkable when the dimension t3 is smaller than the dimension t2 of the groove width of the oil ring groove 4.

  FIG. 4 shows a front view of the piston 1. It can be said that the longitudinal groove 12 is constituted by the end portion 10t and the end portion 10t 'of the eaves portion 10. An R shape is formed at the end 10t and the end 10t '. Here, an enlarged view of a portion surrounded by B-B ′ and C-C ′ is shown in FIG.

  As described above, the vertical groove 12 is formed by the end portion 10t and the end portion 10t 'where the eaves portion 10 is discontinuous. Here, the upward direction of the piston (also simply referred to as “upward direction”) is indicated by an arrow 55. Further, the width of the upper opening of the longitudinal groove 12 is denoted by reference numeral 12u, and the width of the opening of the vertical groove 12 is denoted by reference numeral 12d.

  Here, the vertical groove 12 according to the present invention is formed such that the upper opening width 12u is wider than the lower opening width 12d. In other words, the downward opening width 12d is narrower than the upward opening width 12u.

  FIG. 5B shows a cross section taken along the line D-D ′ shown in FIG. The end portion 10 t and the end portion 10 t ′ of the eaves portion 10 are formed smoothly toward the inside of the piston 1. Specifically, the edges 10y and 10y 'of the longitudinal groove 12 are also given an R shape.

  In this way, the end portion 10t (10t ′) of the groove portion 12 is formed in an R shape, the upper groove width 12u is wider than the lower groove width 12d, and the edge portions 10y and 10y ′ in the depth direction of the groove portion 12 are smooth. Therefore, even if the joint of the piston ring formed from a plurality of pieces is displaced from the oil ring groove 4 toward the groove 12, the oil ring groove 4 is smoothly formed as indicated by the arrows 58 and 58 '. You can go back. Therefore, even if the vertical groove 12 that interrupts the oil ring groove 4 is provided, the oil ring is not caught.

  Further, when the end portion of the eaves portion 10 around the vertical groove 12 is formed in a round shape, the oil can be easily guided to the piston pin hole 6 side, the oil draining performance can be further improved, and the contact area with the cylinder bore can be reduced. You can also.

  In the above embodiment, the vertical groove 12 is formed by piston casting, but may be formed by a subsequent process.

  In the above embodiment, the eaves portions corresponding to the front and back openings of the piston pin hole 6 are all divided by the single vertical groove 12, but at least the depth of the groove portion is shown. Other shapes may be used as long as the groove portion is formed with a depth reaching the side wall surface of the oil ring groove and the eaves portion is divided in the circumferential direction.

  For example, a plurality of vertical grooves may be formed downward from the oil ring groove. Further, the extending direction of the groove portion may not be the vertical direction. Furthermore, the groove part formed in each side of the opening of the front and back of a piston pin hole does not need to be formed in the same shape.

  The present invention can be used for a piston shape of an internal combustion engine, and can be widely used for a piston of an engine that mass-produces vehicles of various grades.

DESCRIPTION OF SYMBOLS 1 Piston 2,102 Compression ring groove | channel 4,104 Oil ring groove | channel 4a Side peripheral wall surface 4b Bottom surface 6,106 Piston pin hole 6a Top surface 8 Groove (groove)
12u Upper groove width 12d Lower groove width 110a Thin portion

Claims (2)

A piston structure in which a compression ring groove, an oil ring groove, and a piston pin hole are formed in order,
The distance between the uppermost surface of the piston pin hole and the lowermost surface of the oil ring groove is smaller than the thickness of the partition wall that separates the compression ring groove and the oil ring groove,
In the eaves part separating the oil ring groove and the piston pin hole,
At a depth reaching the side wall surface of the oil ring groove,
Including the closest position of the oil ring groove and the piston pin hole;
The structure of the piston characterized by the above-mentioned. The groove part which divides the eaves part in the circumferential direction is formed.   2. The piston according to claim 1, wherein an end portion of the eaves portion forming the groove portion is formed in an R shape, and the opening width in the piston downward direction is narrower than the opening width in the piston upward direction. Construction.