JP2008032034A - Piston device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston device for internal combustion engines effective for reducing oil consumption and reducing friction. <P>SOLUTION: Piston rings 6, 7, 8 are fitted into ring grooves 3, 4, 5 formed in the outer peripheral surface of a piston 2 reciprocating in the cylinder 1 of an internal combustion engine 1. A space 12 in which the oil scraped off from the cylinder wall by the second ring 7 is accumulated is formed between a projecting part 11 formed on the lower surface of the second ring 7 and the outer peripheral side end of the second ring groove 4. The second ring 7 is pressed to the outer peripheral side by the hydraulic pressure of the oil accumulated in the space 12. Since the second ring 7 is hydraulically pressed, the tension of the second ring 7 itself is small. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine piston device that is effective in reducing oil consumption and friction.

  In recent years, the demand for low fuel consumption of internal combustion engines for automobiles has increased, and accordingly, the demand for low friction of pistons and piston rings has also increased. Tension reduction is an effective means for reducing the friction of piston rings, but it is difficult to reduce the tension of conventional piston rings as engine performance improves. Conventionally, when the tension of the piston ring is reduced, the width or thickness is reduced, and the performance of the engine is maintained by maintaining the performance of following the cylinder. However, there is a limit to dimensional changes such as thinning, and it is becoming difficult to reduce tension.

Normally, the oil adhering to the cylinder wall is scraped off by the piston ring and returned to the crankcase through the oil return hole or notch provided in the piston. It is not a structure to give. Therefore, when the tension of the piston ring is reduced, the follow-up performance to the cylinder is reduced, the gap between the cylinder wall surface and the piston ring is increased, and the leakage of combustion gas and the oil from the crankcase side to the combustion chamber are increased. It becomes a problem.

In Patent Document 1, as a method of improving the follow-up performance of the piston ring to the cylinder wall, a peripheral surface is formed that opens to the upper surface of the ring and applies the gas pressure introduced from the ring upper surface clearance in the direction of the outer peripheral surface of the ring. A method using gas pressure in which an annular recess is formed has been proposed. Patent Document 2 proposes a ring in which an annular groove formed on the lower surface of the tapered face ring is opened in a gap between the cylinder inner peripheral surface and the piston outer peripheral surface.
JP 2001-31468 A JP 2000-170602 A

However, Patent Document 1 does not describe a technique for improving the followability of the piston ring to the cylinder wall by using the oil pressure of the oil scraped off from the cylinder wall by the piston ring. Further, since the disclosed structure uses the gas pressure, the effect of improving the followability may not be sufficiently exhibited under conditions where the in-cylinder pressure does not increase, such as during negative pressure. In Patent Document 2, since the oil pool space is increased by the annular groove formed on the lower surface of the piston ring, the oil pressure of the piston land portion is lowered and the oil is prevented from flowing back to the combustion chamber side. Thus, it is not shown that the piston ring is pressed to the outer peripheral side. In the annular groove of Patent Document 2, since the hydraulic pressure acts equally on the inside and outside in the radial direction of the piston ring, there is no action of pushing the piston ring outward.

  An object of the present invention is to provide a piston device for an internal combustion engine that is effective in reducing oil consumption and friction.

In order to solve the above problems, the present invention employs the following means. That is,
The present invention relates to a piston device in which a piston ring is mounted in a ring groove on an outer peripheral surface of a piston that reciprocates in a cylinder of an internal combustion engine. It is formed between the protruding part provided on the lower surface and the notch part provided on the outer peripheral side end of the ring groove, and the piston ring is pressed to the outer peripheral side by the hydraulic pressure of the oil accumulated in the space. Features.

  According to the present invention, by providing the oil reservoir space as described above, the oil scraped from the cylinder wall by the piston ring accumulates in the space, and the hydraulic pressure generates a force for pushing the piston ring to the outer peripheral side. The follow-up performance of the ring with respect to the fuel can be improved, the blow-by of the combustion gas can be reduced, and the oil scraping performance is improved. Since oil pressure is used, the oil consumption can be reduced even when the cylinder pressure is negative. Further, since the force (tension) protruding to the cylinder of the piston ring itself can be reduced by the use of the hydraulic pressure, the effect of reducing friction can be obtained in the compression and exhaust strokes.

  The oil reservoir space is formed between the protrusion provided on the lower surface of the piston ring and the notch provided on the outer peripheral end of the ring groove, thereby forming a gap between the piston outer peripheral surface and the cylinder wall surface. Since the facing opening area can be reduced, the oil that has accumulated in the space is suppressed from flowing out, so that a force for pushing out the piston ring more effectively can be obtained.

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

  As shown in FIG. 1, a plurality of ring grooves 3, 4, and 5 are formed on the outer peripheral surface of a piston 2 that reciprocates within a cylinder 1 of an internal combustion engine. Piston rings 6, 7, and 8 are attached to the respective parts. The piston ring is a top ring 6, a second ring 7, and an oil ring 8 in order from the side closer to the combustion chamber. The top ring 6 and the second ring 7 have a function of a compression ring and mainly suppress blow-by gas from the combustion chamber, but also perform an action of scraping oil from the cylinder wall.

  1 and 2 show a case where the present invention is applied to the second ring groove 4 and the second ring 7. The second ring 7 is an annular member having a substantially inverted L-shaped cross section having an abutment, and has an outer peripheral surface 9 of a tapered face whose outer diameter increases downward. On the other hand, the lower corner of the outer ring side end of the second ring groove 4 is notched in a step shape, and the notch 10 is formed over the entire circumference of the ring groove. A protruding portion 11 that protrudes downward from the lower surface of the end portion and is formed over the entire circumference of the ring is disposed. The outer peripheral surface 10 a in the notch 10 of the second ring groove 4 and the inner peripheral surface 11 a of the protrusion 11 of the second ring 7 have a predetermined interval, and the oil reservoir surrounded by the protrusion 11 and the notch 10. A space 12 is formed. The space between the lower surface 11b of the protrusion 11 of the second ring 7 and the upper surface 10b of the notch 10 of the second ring groove 4 is formed narrow, and the opening area that faces the gap between the piston outer peripheral surface 2a and the cylinder inner peripheral surface 1a. Is reduced to suppress the outflow of the oil accumulated in the oil reservoir space 12, thereby obtaining a force for pushing the second ring 7 to the outer peripheral side more effectively.

  Therefore, in the suction stroke or the explosion stroke, the oil adhering to the cylinder inner peripheral surface 1a is scraped off by the second ring 7, flows into the oil ring 8 side, flows into the oil pool space 12, and flows into the oil pool space 12. The oil 13 that satisfies the above condition generates a hydraulic action, exerts an action of pressing the second ring 7 against the inner circumferential surface 1a of the cylinder over the entire circumference, improves the followability of the second ring 7 with respect to the inner circumferential surface 1a, and reduces oil consumption. Has an excellent effect. On the other hand, since the second ring 7 is pressed using hydraulic pressure, the tension of the second ring 7 itself is reduced. Therefore, in the compression stroke and the exhaust stroke, only the tension of the second ring 7 itself is provided, and friction is reduced.

  The result of evaluating oil consumption by the second ring 7 is shown in FIG. FIG. 9 shows relative values when the oil consumption in the conventional product is 1. As can be seen in FIG. 9, the oil consumption was reduced with the product of the present invention in which the ring tension was almost zero.

  Hereinafter, another embodiment of the present invention will be described. Only the differences from the embodiment shown in FIGS. 1 and 2 will be described.

  FIG. 3 shows a case in which the lower corner of the outer ring side end of the second ring groove 4 is cut into a chamfered shape to form a cutout 10, and the oil surrounded by the protrusion 11 and the cutout 10. A pool space 12 is formed. The distance between the lower end of the inner periphery of the protrusion 11 of the second ring 7 and the inclined surface 10c of the notch 10 of the second ring groove 4 is narrow, and the opening faces the gap between the piston outer peripheral surface 2a and the cylinder inner peripheral surface 1a. The area is small.

  In the second ring 7 shown in FIG. 2, chamfering is formed at the corner of the inner peripheral upper end of the protruding portion 11. On the other hand, FIG. 4 does not form a chamfer.

FIG. 5 shows the shape of the inner peripheral surface of the projecting portion 11 of the second ring 7 and the lower surface adjacent thereto so as to expand the oil reservoir space 12 toward the cylinder 1 side.

  In FIG. 6, a groove 14 having a triangular cross section is formed on the lower surface portion adjacent to the protrusion 11 of the second ring 7 so that the oil reservoir space 12 is enlarged toward the cylinder 1 side.

  FIG. 7 shows an inner peripheral protrusion 15 that protrudes radially inward on the inner peripheral side at the lower end of the protrusion 11 in the second ring 7 over the entire circumference of the ring.

  In FIG. 8, the lower corner of the outer ring side end of the second ring groove 4 is cut into a chamfered shape to form a notch 10, and the lower end of the projecting portion 11 in the second ring 7 has a bowl shape on the inner peripheral side. A protruding inner peripheral protruding portion 15 is formed over the entire circumference of the ring. The lower surface of the protruding portion 11 of the second ring 7 and the inclined surface 10c of the notched portion 10 of the second ring groove 4 are arranged in parallel, and the distance between them is narrow, and the gap between the piston outer peripheral surface 2a and the cylinder inner peripheral surface 1a. The opening area that faces is made small.

  In addition, although the example which applied this invention to the second ring groove | channel and the second ring was shown in the above embodiment, this invention is not limited to this.

It is a longitudinal cross-sectional view which shows the cylinder part of the internal combustion engine equipped with the piston apparatus which is one Embodiment of this invention. It is an enlarged view which shows a part of FIG. It is a longitudinal cross-sectional view of the second ring part which shows another embodiment of this invention. It is a longitudinal cross-sectional view of the second ring part which shows another embodiment of this invention. It is a longitudinal cross-sectional view of the second ring part which shows another embodiment of this invention. It is a longitudinal cross-sectional view of the second ring part which shows another embodiment of this invention. It is a longitudinal cross-sectional view of the second ring part which shows another embodiment of this invention. It is a longitudinal cross-sectional view of the second ring part which shows another embodiment of this invention. It is a figure which shows an oil consumption test result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 1a Cylinder inner peripheral surface 2 Piston 2a Piston outer peripheral surface 3 Top ring groove 4 Second ring groove 5 Oil ring groove 6 Top ring 7 Second ring 8 Oil ring 9 Second ring outer peripheral surface 10 Notch 10a Notch outer surface 10b Notch Upper surface 10c Notch slope 11 Projection 11a Projection inner peripheral surface 11b Projection lower surface 12 Oil pool space 13 Oil 14 Ring lower surface groove 15 Inner projection

Claims (1)

  In a piston device in which a piston ring is mounted in a ring groove on the outer peripheral surface of a piston that reciprocates in a cylinder of an internal combustion engine, a space for storing oil scraped off from the cylinder wall by the piston ring is provided on the lower surface of the piston ring. The piston ring is pressed to the outer peripheral side by the oil pressure of the oil accumulated in the space, which is formed between the protruding portion and the notch provided at the outer peripheral end of the ring groove. Piston device for engine.

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