JP2006322390A - Piston - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston effective for reduction of blow-by gas and oil consumption. <P>SOLUTION: In the piston including a plurality of piston ring grooves 3, 4, 5 on an outer circumference of the piston 2, a plurality of recess parts 11 are formed on a second land 10 between the adjoining two pressure ring grooves 3, 4 at an interval in a circumference direction. Each recess part 11 is separated in the circumference direction by a bulkhead, and a land part is left and exists between the recess parts 11 and the two pressure ring grooves 3, 4. It is also preferable to form the recess part on a third land 12 between the pressure ring groove 4 and an oil ring groove 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine and a piston for a compressor that are effective in reducing blow-by gas and oil consumption.

  In general, an internal combustion engine and a piston for a compressor are used in which lands between piston ring grooves have a uniform surface without unevenness in the circumferential direction. In order to improve oil consumption, proposals have been made to improve the land between the piston ring grooves.

  In Patent Document 1, a piston land between a pressure ring groove and a pressure ring groove, or a piston land between a pressure ring groove and an oil ring groove, is continuously provided with a notch having a wedge-shaped cross section over the entire circumference. By securing the oil retaining volume of the space surrounded by the ring, land, and cylinder bore and lowering the oil pressure, the oil consumption at the time of load and at the time of low load is prevented from deteriorating. Further, since the oil retaining volume is secured by the notch, it is not necessary to reduce the outer diameter of the land directly under the pressure ring, and it can be expected to prevent an increase in blow-by gas.

  In Patent Document 2, a plurality of notches that are depressed in the piston radial direction in the piston land between the pressure ring groove and the oil ring groove and communicate with both the pressure ring groove and the oil ring groove or the oil ring groove are provided in the circumferential direction. By forming with a gap, while maintaining the proper posture of the oil ring, it secures the oil retention volume of the space surrounded by the piston ring, land, and cylinder bore, and provides good oil scuffing performance by the oil ring. It has gained.

In Patent Document 3, at least the cylinder inner surface is in the cylinder axial direction so that the space portion is partitioned and sealed in the circumferential direction in an annular space formed by two pressure rings, a piston land between the two rings, and the cylinder inner surface. An auxiliary ring having a plurality of protrusions in line in the circumferential direction is attached to block gas and oil moving in the land portion to reduce blow-by gas and oil consumption.
Japanese Patent No. 3120918 JP-A-5-280417 Japanese Utility Model Publication No. 63-14042

  In the piston structure where the land between the piston ring grooves has a uniform surface with no irregularities in the circumferential direction, the upward movement of oil under negative pressure is a linear distance between the joints of the adjacent upper and lower piston rings. Therefore, the oil is quickly sucked into the combustion chamber, and the oil consumption is likely to increase. On the other hand, in order to secure the oil retaining volume in the space surrounded by the piston ring, land, and cylinder bore and reduce the oil pressure, the outer diameter of the land must be reduced and the blow-by gas increases due to the increased gas passage area. To do. Further, by reducing the land outer diameter, the posture of the piston ring is deteriorated, which causes an increase in oil consumption and deterioration of blow-by gas.

  In Patent Document 1, since the space surrounded by the piston ring, the land, and the cylinder bore is uniform in the circumferential direction, the pressure is also constant in the circumferential direction, and a labyrinth effect cannot be expected, so that a sufficient effect cannot be obtained.

  In Patent Document 2, since the notch portion communicates with the piston ring groove, especially on the pressure ring side, when the notch portion and the ring abutment portion overlap, the gas passage area increases and blow-by gas increases. On the oil ring side, when the cutout portion and the ring joint portion overlap, the oil passage area increases, the oil rise at the time of negative pressure increases, and the oil consumption deteriorates.

  In Patent Document 3, the space between the protrusions of the auxiliary ring communicates with the upper and lower piston ring grooves, and the land diameter must be smaller than usual in order to fit the auxiliary ring, and in particular, the upper and lower pressure rings. When the abutment position overlaps the same space, a large amount of blow-by gas flows downward. Similarly, a large amount of oil moves upward during deceleration. Furthermore, the piston, the auxiliary ring, and the inner circumference of the cylinder are in contact with each other. Particularly, since the auxiliary ring and the inner circumference of the cylinder are in line contact with each other, there is a high possibility that the inner circumference of the cylinder is damaged by the swinging motion of the piston.

  The problem to be solved by the present invention is to provide a piston that is effective in reducing blow-by gas and oil consumption.

In order to solve the above problems, the present invention employs the following means. That is,
In the piston having a plurality of piston ring grooves on the outer periphery of the piston, a plurality of recesses are formed in the land between adjacent piston ring grooves at intervals in the circumferential direction. There is a land portion between them.

  The recess includes a land between the pressure ring groove and the pressure ring groove, a land between the pressure ring groove and the oil ring groove, or a land between the pressure ring groove and the pressure ring groove, and the pressure ring groove and the oil ring. It is formed in the land between the grooves.

  The piston of the present invention has a labyrinth effect in the circumferential direction because a plurality of recesses formed in the lands between adjacent piston ring grooves are separated from each other by a partition wall in the circumferential direction. As a result, when the oil moves to the combustion chamber side through the joint of the piston ring, the oil movement in the circumferential direction is delayed at the piston land portion, which has an effect of reducing oil consumption. In addition, a sufficient volume of the space surrounded by the piston ring, the land, and the cylinder bore can be secured, and the hydraulic pressure can be lowered, so that oil rising to the combustion chamber can be reduced, and increase in oil consumption can be prevented. In addition, the volume of the space can be sufficiently secured and the gas pressure can be lowered, so that the piston ring behavior can be stabilized, the blow-by gas can be reduced, and the oil rising to the combustion chamber side can be reduced to reduce oil consumption. Increase can be prevented. Further, since it is not necessary to reduce the land outer diameter, there is no increase in blow-by gas.

  In addition, the concave portion is formed in the land between the pressure ring groove and the pressure ring groove in the case of the three ring configuration, or in the land between the pressure ring groove and the oil ring groove in the case of the two ring configuration. If this is the case, the labyrinth effect in the circumferential direction can alleviate the effect of load fluctuations and reduce oil consumption during pattern operation.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

  In FIG. 1 to FIG. 3, 1 is a cylinder and 2 is a piston inserted into the cylinder 1. Two pressure ring grooves 3 and 4 and one oil ring groove 5 are formed on the outer periphery of the piston 2 in order from the combustion chamber side. An oil return hole 6 is formed in the oil ring groove 5. A top ring 7 and a second ring 8 which are pressure rings are mounted on the two pressure ring grooves 3 and 4, respectively, and a two-piece combination oil ring 9 with a coil expander is mounted on the oil ring groove 5.

  In the piston 2, a plurality of recesses 11 are formed at equal intervals in the circumferential direction in the second land 10 sandwiched between the two pressure ring grooves 3 and 4. The recesses 11 are separated from each other by a partition wall, and a land portion is left between the recess 11 and the two pressure ring grooves 3 and 4. The circumferential length, axial width, radial depth, and number of the recesses 11 are appropriately selected in consideration of engine performance and piston land strength. The recess 11 is prevented from penetrating the back surface of the piston 2. Although the manufacturing method of the recessed part 11 is not specifically limited, It can manufacture without a spot facing process with a drill, an end mill, a milling cutter, etc. or without casting.

  Therefore, the piston 2 of the present invention has a plurality of recesses 11 in the second land 10, and the recesses 11 are separated from each other by the partition walls in the circumferential direction, and thus have a labyrinth effect in the circumferential direction. As a result, when the oil moves from the joint of the second ring 8 to the joint of the top ring 7 through the second land 10, the oil movement in the circumferential direction is delayed in the second land 10, which has an effect of reducing oil consumption. Moreover, since the volume of the space surrounded by the top ring 7, the second ring 8, the second land 10, and the inner periphery of the cylinder 1 can be sufficiently secured and the hydraulic pressure can be lowered, the oil rising to the combustion chamber side can be reduced, Increase in oil consumption can be prevented. In addition, the volume of the space can be secured sufficiently, and the gas pressure can be lowered, so that the behavior of the top ring 7 can be stabilized, blow-by gas can be reduced, and the oil rising to the combustion chamber can be reduced to reduce oil consumption. Can be prevented. Moreover, since it is not necessary to make the outer diameter of the second land 10 small, there is no increase in blow-by gas. Further, when the concave portion 11 is formed in the second land 10 between the two pressure ring grooves 3 and 4, the influence of load fluctuation is mitigated by the labyrinth effect in the circumferential direction, and the oil consumption during pattern operation is reduced. Is effective.

  4-6 illustrate another embodiment of the present invention. The difference between the present embodiment and the above embodiment is the location where the recess is formed, and the other configuration is the same as that of the above embodiment.

  In the present embodiment, in the piston 2, a plurality of recesses 13 are formed at equal intervals in the circumferential direction in a third land 12 sandwiched between the oil ring groove 5 and the pressure ring groove 4 immediately above it. Each recess 13 is separated from each other by a partition wall in the circumferential direction. Further, a land portion is left between the recess 13 and the pressure ring groove 4 immediately above and between the recess 13 and the oil ring groove 5. Existing. The circumferential length, axial width, radial depth, and number of the recesses 13 are appropriately selected in consideration of engine performance and piston land strength. The recess 13 is prevented from penetrating the back surface of the piston 2. Although the manufacturing method of the recessed part 13 is not specifically limited, It can manufacture without a spot facing process or casting with a drill, an end mill, a milling cutter, etc.

  Therefore, the piston 2 of the present invention exhibits the same effect as the above embodiment, and is effective in reducing oil consumption and blow-by gas.

  7 to 9 show still another embodiment of the present invention. The difference between the present embodiment and the embodiment is the formation of a recess, and other configurations are the same as those of the embodiment.

  In the present embodiment, in the piston 2, a plurality of second lands 10 between the two pressure ring grooves 3 and 4 and a third land 12 between the oil ring groove 5 and the pressure ring groove 4 immediately above the oil ring groove 5 are provided. The recesses 11 and 13 are formed at equal intervals in the circumferential direction. The recesses 11 and 13 are separated from each other by a partition wall in the circumferential direction, and further between the recess 11 and the two pressure ring grooves 3 and 4, and between the recess 13 and the pressure ring groove 4 immediately above it, and Land portions remain between the recess 13 and the oil ring groove 5. The circumferential length, axial width, radial depth, and number of the recesses 11 and 13 are appropriately selected in consideration of the performance of the engine and the strength of the piston land. Further, the recesses 11 and 13 are prevented from penetrating the back surface of the piston 2. Although the manufacturing method of the recessed parts 11 and 13 is not specifically limited, It can manufacture without counterbore processing or casting with a drill, an end mill, a milling cutter, etc.

  Therefore, the piston 2 of the present invention exhibits the effects of the two embodiments, and is effective in reducing oil consumption and blow-by gas.

  As described above, the recesses 11 and 13 may be appropriately selected in consideration of the performance of the engine and the strength of the piston land in accordance with the circumferential length, the axial width, the radial depth, and the number. It is not limited to what is shown in the form. Other examples of the recesses are shown in FIGS.

  The concave portions 11 and 13 of the embodiment are concave portions having a constant axial width as viewed from the front, elongated in the circumferential direction, arc-shaped at both ends, and a constant depth. On the other hand, the recessed part 11 shown in FIG.11 and FIG.12 makes the both ends of the circumferential direction linear. The recess 11 shown in FIGS. 13 and 14 has a shorter circumferential length than the recess shown in FIGS. 11 and 12. The concave portion 11 shown in FIGS. 15 and 16 has a concave bottom surface different from that shown in FIGS. 13 and 14 and has a circular bottom surface in the circumferential direction. The recess 11 shown in FIGS. 17 and 18 is a recess having a circular shape and a constant depth when viewed from the front.

It is a front view which shows one Embodiment of the piston of this invention. It is the sectional view on the AA line of FIG. It is a principal part longitudinal cross-sectional view of the cylinder equipped with the piston of FIG. 1 provided with a piston ring. It is a front view which shows another embodiment of the piston of this invention. It is the sectional view on the AA line of FIG. It is a principal part longitudinal cross-sectional view of the cylinder equipped with the piston of FIG. 4 provided with a piston ring. It is a front view which shows another embodiment of the piston of this invention. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is a principal part longitudinal cross-sectional view of the cylinder equipped with the piston of FIG. 7 provided with a piston ring. It is a front view which shows another embodiment of the piston of this invention. It is the sectional view on the AA line of FIG. It is a front view which shows another embodiment of the piston of this invention. It is AA sectional view taken on the line of FIG. It is a front view which shows another embodiment of the piston of this invention. It is the sectional view on the AA line of FIG. It is a front view which shows another embodiment of the piston of this invention. It is the sectional view on the AA line of FIG.

Explanation of symbols

  1 ・ ・ Cylinder, 2 ・ ・ Piston, 3 ・ ・ ・ Pressure ring groove, 5 ・ ・ Oil ring groove, 6 ・ ・ Oil return hole, 7,8 ・ ・ Pressure ring, 9 ・ ・ Oil ring, 10 ・ ・Second land, 11, 13, ..., recess, 12 ... third land.

Claims (4)

  In a piston having a plurality of piston ring grooves on the outer periphery of the piston, a plurality of recesses are formed in the land between adjacent piston ring grooves at intervals in the circumferential direction, and a land is formed between the recess and the piston ring groove. Piston characterized by the presence of a part.   The piston according to claim 1, wherein the recess is formed in a land between the pressure ring groove and the pressure ring groove.   The piston according to claim 1, wherein the recess is formed in a land between the pressure ring groove and the oil ring groove.   The piston according to claim 1, wherein the recess is formed in a land between the pressure ring groove and the pressure ring groove and in a land between the pressure ring groove and the oil ring groove.

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