JP2001241357A - Combination of piston ring and piston using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combination of piston rings preventing a lubricating oil from being sucked into a combustion chamber even when high negative pressure occurs within a cylinder by adopting a variable cylinder engine and driving a conventional engine within the zone of an engine brake. SOLUTION: The first pressure ring 3, the second pressure ring 4 and an oil ring 5 are successively arranged from the combustion chamber side in ring grooves 6a, 6b, 6c, and the pressure ring of a double lap abutment 9 is used for the ring 4. Combustion gas and the lubricating oil are allowed to pass from the combustion chamber to the oil pan side and not allowed to pass from the latter to the former. Consequently, the lubricating oil can be prevented from running out from the abutment 9 of the ring 4 to the combustion chamber side even when the high negative pressure occurs within the cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combination of a piston ring in which a first pressure ring, a second pressure ring, and an oil ring are sequentially arranged in a ring groove from a combustion chamber side, and a piston using the combination. The present invention relates to a combination of piston rings used for a cylinder engine.

[0002]

2. Description of the Related Art As a combination of piston rings, a three-ring structure in which two pressure rings are mounted on a combustion chamber side of a piston body and an oil ring is mounted on an oil pan side of the pressure ring is generally used. . Three rows of annular ring grooves are formed on the outer periphery of the piston body. A first pressure ring, a second pressure ring, and an oil ring are sequentially arranged in the ring groove from the combustion chamber side. As the joint between the first pressure ring and the second pressure ring, a straight joint, that is, a joint obtained by cutting the pressure ring in a direction orthogonal to the circumferential direction is used in consideration of manufacturing cost and the like. The combination of the three rings of the piston ring prevents airtightness of the combustion chamber and leakage of lubricating oil to the combustion chamber.

There is known a variable cylinder engine in which operation of some cylinders is stopped under predetermined operating conditions and reduced cylinder operation is performed in the remaining cylinders. In a normal engine, for example, in the case of a six-cylinder engine, all six cylinders are sequentially operated for each cylinder to produce smooth rotation. On the other hand, this variable-cylinder engine does not operate all six cylinders when a load is not required to save resources, for example, operates only half of the six cylinders and stops the remaining three cylinders. Typically, it is operated continuously with the valve fully closed.

[0004]

However, when a conventional piston ring combination is applied to the piston of this variable cylinder engine, the piston is lowered in a state where the fuel supply valve is fully closed, so that the cylinder has a vacuum. , And a problem occurs that the lubricating oil is sucked into the combustion chamber. The sucked lubricant has no place to escape because the valve is closed and accumulates in the cylinder. When the variable cylinders are released and all cylinders are operated, the sucked lubricating oil burns, resulting in increased lubricating oil supply, carbon sludge, and air pollution. Would.

[0005] Negative pressure close to vacuum in a cylinder is generated not only when a variable cylinder engine but also a normal engine is operated in an engine braking range, causing the above-described problem.

Accordingly, the present invention employs a variable-cylinder engine and operates a normal engine in an engine braking range, so that even if a high negative pressure is generated in the cylinder, the lubricating oil remains in the combustion chamber. An object of the present invention is to provide a piston ring combination that is not sucked up and a piston using the combination.

[0007]

Means for Solving the Problems To solve the above problems, the present inventor has proposed that when a high negative pressure is generated in a cylinder,
It was noted that the lubricating oil was sucked into the combustion chamber through the joint of the pressure ring. In order to stop the lubricating oil from being sucked into the combustion chamber, the joint of the second pressure ring closest to the oil ring should be a double wrap joint, and the structure should be such that lubricating oil cannot pass from the joint to the combustion chamber. I found the best. Specifically, the present invention provides a combination of a piston ring in which a first pressure ring, a second pressure ring, and an oil ring are sequentially arranged in a ring groove from the combustion chamber side, wherein the second pressure ring is provided on one of the abutting end sides. A piston ring comprising a double wrap abutment pressure ring provided with an outer peripheral surface and a convex portion having a triangular cross section extending in a circumferential direction from one side surface and a concave portion engaged with the convex portion at the other abutment end side. The above-mentioned problem has been solved by the combination of.

[0008] Originally, the pressure ring of the double wrap joint,
It is often used for a pressure ring having a two-ring configuration in which the size of the engine is reduced or the friction loss is reduced. By employing an oil ring with a double wrap abutment as the first pressure ring on the combustion chamber side, the sealing performance of the combustion chamber can be improved even with a two-ring configuration. However, according to the present invention, the combustion gas and the lubricating oil are passed from the combustion chamber side to the oil pan side by using the pressure ring of the double wrap abutment for the second pressure ring instead of the first pressure ring. The combustion gas and the lubricating oil can be prevented from passing from the pan side to the combustion chamber side, so that even if a high negative pressure is generated in the cylinder, the lubricating oil flows from the joint of the second pressure ring to the combustion chamber side. Flow can be prevented.

Further, the present invention is characterized in that the combination of the piston rings is used in a variable cylinder engine in which operation of some cylinders is stopped under predetermined operating conditions and reduced cylinder operation is performed in the remaining cylinders. .

In a variable cylinder engine in which operation of some cylinders is stopped under predetermined operating conditions and reduced cylinder operation is performed in the remaining cylinders, some of the cylinders are continuously operated with their valves fully closed, and the cylinders are operated continuously. The inside becomes high negative pressure close to vacuum. Since the present invention can prevent the lubricating oil from flowing to the combustion chamber side, it is a very effective combination of a piston ring in a variable cylinder engine, that is, a piston in which high negative pressure is generated in the cylinder. .

Further, the present invention is characterized in that the one side surface on which the convex portion of the second pressure ring extends is arranged on a combustion chamber side.

The double wrap abutment used for the abutment of the first pressure ring having the conventional two-ring structure has a convex portion of the first pressure ring extending on one side and an oil pan side in order to enhance the sealing performance of the combustion chamber. Be placed. On the other hand, according to the present invention, since the one side surface on which the convex portion of the second pressure ring extends is disposed on the combustion chamber side, the following operations and effects are achieved. In the normal operating state of the acceleration range and the load range, the blow-by gas flows from the combustion chamber side to the oil pan side through the joint due to the pressure difference between the upper and lower sides of the second pressure ring, and the lubricating oil is blown down by this action. On the other hand, in a variable cylinder mechanism operating state or an engine brake operating state in which the inside of the cylinder becomes a high negative pressure, the negative pressure causes gas to flow back to the combustion chamber side, and the lubricating oil passes through the junction of the second pressure ring due to the negative pressure. However, the double wrap abutment structure of the second pressure ring blocks the backflow of lubricating oil into the combustion chamber. That is, according to the present invention, the combustion chamber and the lubricating oil pass from the abutment to the oil pan side, but the combustion chamber and the lubricating oil do not pass from the abutment to the combustion chamber side. It is possible to prevent the oil from flowing from the oil pan side to the combustion chamber side through the joint of the second pressure ring.

Further, the present invention provides the first pressure ring,
It is characterized by comprising a straight joint pressure ring. The straight joint is a joint obtained by cutting both joint ends of the pressure ring in a direction perpendicular to the circumferential direction of the ring, and both joint ends have a planar shape.

If a pressure ring having a double wrap joint is used as the first pressure ring, the sealing performance of the combustion chamber can be improved, but the thickness of the pressure ring is reduced due to the problem of the strength of the joint, especially the convex portion. It is not possible to reduce the thickness of the pressure ring itself, thereby making it impossible to reduce the weight of the pressure ring itself, causing fluttering on the high-speed rotation side during light-load operation, that is, fluttering of the first pressure ring, resulting in blow-by gas There is a problem that it increases. According to the present invention, by using a straight abutment ring as the first pressure ring, the thickness of the first pressure ring can be reduced, and accordingly, the weight of the first pressure ring itself can be reduced, It is also possible to prevent the blow-by gas from rapidly increasing due to adhesion between the first pressure ring and the piston and fluttering during light load and high rotation.

Further, the present invention provides a piston in which a first pressure ring, a second pressure ring and an oil ring are arranged in a ring groove from a combustion chamber side, wherein the second pressure ring is
A double wrap abutment pressure ring having a triangular cross-sectional protrusion extending in the circumferential direction from the outer peripheral surface and one side surface at one abutment end side, and a concave portion engaging with the protrusion at the other abutment end side. It can also be configured as a featured piston.

[0016]

FIG. 1 shows a piston 1 to which a combination of piston rings according to an embodiment of the present invention is applied. This piston 1 is used for a four-cycle gasoline engine, and particularly for a variable cylinder engine. Variable-cylinder engines tend to improve fuel efficiency when the engine is operated under a high load condition.Therefore, under certain operating conditions, for example, when the engine is lightly loaded, the fuel of some cylinders is shut off, and Cylinder operation is stopped and the remaining cylinders are relatively reduced in load by increasing the load on the other cylinders.On the other hand, except in the light load state, fuel is supplied to the stopped cylinders to make the cylinder into an operating state. To improve. This combination of piston rings is a very effective combination of piston rings for a piston in a variable cylinder engine where high negative pressure is generated in the cylinder, but high negative pressure is generated in the cylinder even in the engine braking range of a normal engine. This is an effective combination for normal engine pistons.

The combination of the piston rings is a three-ring configuration in which two pressure rings 3 and 4 are mounted on the piston body 2 and an oil ring 5 is mounted below the pressure rings 3 and 4. On the outer periphery of the piston body 2, annular ring grooves 6a, 6b, 6c are formed in three rows in the vertical direction.
The first pressure ring 3, the second pressure ring 4, and the oil ring 5 are sequentially arranged in the ring grooves 6a, 6b, 6c from the combustion chamber side. For the first pressure ring 3, for example, a barrel face rectangular ring whose central portion of the outer peripheral surface is bulged is used, and for the second pressure ring 4, for example, a tapered face rectangular shape in which the outer peripheral surface is tapered. A ring is used, and the oil ring 5 is, for example, a steel combination oil ring. The first pressure ring 3
Is not limited to the barrel face, the second pressure ring 4 is not limited to the tapered face, and the oil ring 5 is not limited to the oil ring of steel combination.

At the joint of the first pressure ring 3, a straight joint 7 is used. The straight joint 7 is a joint formed by cutting both joint ends 8a, 8b of the first pressure ring 3 in a direction orthogonal to the circumferential direction of the first pressure ring 3, and both joint ends 8a, 8b have a planar shape.

By using a straight-joint pressure ring as the first pressure ring 3, the thickness of the first pressure ring 3 can be reduced, and accordingly, the weight of the first pressure ring 3 itself can be reduced. In addition, it is possible to prevent the adhesion between the first pressure ring 3 and the piston main body 2 and a sudden increase in blow-by gas due to fluttering during high-speed rotation under light load. As described above, it is desirable to use a straight joint for the first pressure ring. However, the joint of the first pressure ring is not limited to the straight joint, and a double wrap joint may be used depending on the purpose of use of the engine. Of course it is good. .

FIG. 2 shows the abutment of the second pressure ring 4.
A double wrap abutment 9 is used at the abutment of the second pressure ring 4. Double wrap abutment 9 is one abutment end 10a
This is an abutment provided with a convex portion 13 having a triangular cross section extending in the circumferential direction from the outer peripheral surface 11 and the one side surface 12 on the side, and a concave portion 14 engaging with the convex portion 13 on the other abutment end 10b side. As shown in FIG. 1, in the second pressure ring 4, the one side surface 12 on which the protrusion 13 extends is disposed on the combustion chamber side (upper side in the figure).

FIGS. 3 and 4 show a double lap joint 9 of the second pressure ring 4 in a normal acceleration range and a load range.
FIG. Second pressure ring 4
Due to the upper and lower pressure difference, the lower side surface 16 of the second pressure ring 4
Are in close contact with the lower wall surface 15 of the ring groove 6b. The combustion gas flows through the gap between the upper wall surface 16 of the ring groove 6b and the one (upper) side surface 12 of the second pressure ring 4 and flows into the space behind the second pressure ring 4, and the gap at the joint 9 Flows into. Since a slight gap W is provided between the two ends 10a and 10b, the combustion gas flows from the combustion chamber side to the oil pan side through the gap W of the junction 9. This action blows down the lubricating oil.

FIG. 5 shows the flow of the lubricating oil in a variable cylinder mechanism operating state or an engine brake operating state when the inside of the cylinder has a high negative pressure. When the inside of the cylinder has a high negative pressure, one (upper) side surface 12 of the second pressure ring 4 comes into close contact with the upper wall surface 16 of the ring groove 6b. The lubricating oil passes through a gap between the lower wall surface 15 of the ring groove 6b and the other (lower) side surface 16 of the second pressure ring 4 and flows into the space behind the second pressure ring 4, and at the abutment portion. Flows into the gap. However, the one (upper) side surface 12 of the second pressure ring 4 is in close contact with the upper wall surface 16 of the ring groove 6b, and the second pressure ring 4 originally has a tension outward and is in close contact with the cylinder 17. ,
Lubricating oil does not flow into the combustion chamber through the joint.

As described above, by using the double wrap abutment 9 for the second pressure ring 4, the combustion gas and the lubricating oil pass from the combustion chamber side to the oil pan side, but the combustion gas flows from the oil pan side to the combustion chamber side. Gas and lubricating oil can be prevented from passing, and even if a high negative pressure is generated in the cylinder, it is possible to reliably prevent the lubricating oil from flowing from the double wrap joint 9 of the second pressure ring 4 to the combustion chamber side. it can. Even if the lubricating oil leaks from the second pressure ring 4, the second pressure ring 4
Above the first pressure ring 3,
The pressure ring 3 prevents the lubricating oil from leaking into the combustion chamber.

FIG. 6 shows the consumption of lubricating oil at high speed and full load.
It is a comparison between a piston to which a combination of a conventional oil ring is applied and a piston to which a combination of an oil ring of the present invention is applied. In the conventional piston, the lubricating oil consumption is about 95 g / h at a full load of 6,000 revolutions, whereas in the piston of the present invention, it is about 30 g / h, and the lubricating oil consumption in a high-speed full load region is reduced. I was able to.

FIG. 7 shows a comparison of the amount of lubricating oil consumed in the engine braking region between a piston to which the conventional oil ring combination is applied and a piston to which the oil ring combination of the present invention is applied. In the conventional piston, the lubricating oil consumption in the pattern operation is about 160 g / h, whereas in the piston of the present invention, it is about 50 g / h. The amount of lubricating oil consumed in the engine brake region increases for both the piston using the conventional oil ring combination and the piston using the oil ring combination of the present invention,
The piston of the present invention was able to drastically reduce the amount of lubricating oil consumed in the engine brake range as compared with the conventional piston.

FIG. 8 shows a comparison of blow-by curves between a piston to which the conventional oil ring combination is applied and a piston to which the oil ring combination of the present invention is applied. In the conventional piston, the blow-by gas increases on the high-speed rotation side exceeding the engine rotation speed of 4000 r / m during the light load operation, whereas the piston of the present invention substantially reduces the blow-by gas amount at any rotation speed during the light load operation. It can be kept constant, and a rapid increase in blow-by gas on the high-speed rotation side can be prevented. Further, the piston of the present invention was able to keep the blow-by gas amount substantially constant at all rotational speeds even at full load.

[0027]

As described above, according to the present invention,
In the combination of the piston ring in which the first pressure ring, the second pressure ring, and the oil ring are sequentially arranged in the ring groove from the combustion chamber side, a double wrap abutment pressure ring is used for the second pressure ring. Although the combustion gas and the lubricating oil pass through the oil pan side, the combustion gas and the lubricating oil do not pass through from the oil pan side to the combustion chamber side. Lubricating oil can be prevented from flowing from the joint of the pressure ring to the combustion chamber side.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a piston to which a combination of piston rings according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view showing an abutment of a second pressure ring.

FIG. 3 is a cross-sectional view showing blow-through of combustion gas at a second pressure ring joint in an operating state in a normal acceleration region and a load region.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a cross-sectional view showing a flow of lubricating oil in a variable cylinder mechanism operating state or an engine brake operating state when the inside of the cylinder has a high negative pressure.

FIG. 6 is a graph comparing the amount of lubricating oil consumption between the conventional piston and the piston of the present invention in a high-speed full load region.

FIG. 7 is a graph comparing the amount of lubricating oil consumption in the engine brake region between the conventional piston and the piston of the present invention.

FIG. 8 is a graph comparing blow-by curves between a conventional piston and the piston of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston 3 1st pressure ring 4 2nd pressure ring 5 Oil ring 6a, 6b, 6c Ring groove 7 Straight joint 9 Double lap joint 10a One joint end 10b The other joint end 11 Outer peripheral surface 12 One side surface 13 Convex part 14 Concave part

Claims (5)

[Claims] 1. A combination of a piston ring in which a first pressure ring, a second pressure ring, and an oil ring are sequentially arranged in a ring groove from a combustion chamber side, wherein the second pressure ring has an outer peripheral surface and an outer peripheral surface on one abutting end side. On the other hand, a convex portion with a triangular cross section extending in the circumferential direction from the side surface is provided,
A combination of piston rings comprising a double wrap abutment pressure ring provided with a recess at the other abutment end side to engage with the projection. 2. The combination of piston rings according to claim 1, wherein the combination is used for a variable cylinder engine that stops operation of some cylinders under predetermined operating conditions and performs reduced cylinder operation on the remaining cylinders. Combination of the described piston rings. 3. The piston ring combination according to claim 1, wherein the one side surface of the second pressure ring, on which the protrusion extends, is disposed on a combustion chamber side. 4. The piston ring combination according to claim 1, wherein said first pressure ring comprises a straight joint pressure ring. 5. A piston in which a first pressure ring, a second pressure ring, and an oil ring are sequentially arranged in a ring groove from a combustion chamber side, wherein the second pressure ring is provided at one abutment end side from an outer peripheral surface and one side surface. Providing a convex part with a triangular cross section extending in the circumferential direction,
A piston comprising a double wrap abutment pressure ring provided with a concave portion at the other abutment end side for engaging with a convex portion.