JPH0129978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for sealing between a piston ring provided on a piston that reciprocates within a cylinder liner of an internal combustion engine and the inner peripheral surface of a cylinder liner.

In recent years, the quality of fuel oil used in marine diesel engines has deteriorated, and fine hard particles are often mixed in the fuel oil. The hard particles are, for example, highly hard carbon which is a catalyst or is also a fuel residue. If such hard particles get between the piston ring and cylinder liner,
Their wear will increase. On the other hand, the combustion pressure of engines tends to gradually increase, and the surface pressure of the top ring of the piston is becoming extremely severe.

In order to solve such problems, conventionally,
The inner peripheral surface of the cylinder liner and the piston ring are made highly hard, the cylinder liner is sufficiently cooled, or a structure is adopted to remove these hard particles before the fuel oil enters the combustion chamber. However, none of these prior art fundamentally solves the problem of wear.

An object of the present invention is to provide a sealing device for an internal combustion engine that reduces the surface pressure of the top ring and prevents highly hard particles from entering between the cylinder liner and piston ring and abrading them. be.

In the present invention, a plurality of ring grooves are formed on the outer periphery of the piston at intervals in the axial direction thereof, and a piston ring is fitted into each ring groove,
In a sealing device for an internal combustion engine configured such that the outer circumferential surface of a piston ring is in sliding contact with the inner circumferential surface of a cylinder liner, the cylinder liner is supplied with high pressure gas from a high pressure gas supply device. A hole is formed, and this high-pressure gas has a pressure higher than the highest pressure in the combustion chamber. The high-pressure gas supply device is formed at a position between a top ring closer to the room and a second ring adjacent to the top ring, and the top ring is located further away from the cylinder head than the gas introduction hole. the land between the first ring groove in which the top ring is fitted and the second ring groove in which the second ring is fitted among the ring grooves; Then, with the top ring in contact with the lower surface of the first ring groove that is far from the cylinder head, the first and second
This is a sealing device for an internal combustion engine, characterized in that a communication portion that communicates between ring grooves is formed.

FIG. 1 is a sectional view of an embodiment of the present invention. Inside the cylinder liner 1, a piston 2 reciprocates up and down in FIG. A cylinder head 8 is mounted on the cylinder liner 1. piston 2
A top ring 3 and a second piston ring 4 are provided in this order from the combustion chamber 9 side, and furthermore, other piston rings are provided. A gas introduction hole 6 is formed in the cylinder liner 1 .

Gas such as high-pressure air from the high-pressure compressor 11 is cooled by a cooler 12, stored in a high-pressure container 13, and supplied to the gas introduction hole 6 from a pipe 14 via a high-pressure gas supply device 15. This high pressure gas supply device 15 is controlled to open and close in synchronization with the crankshaft.

FIG. 2 is an enlarged sectional view of the vicinity of the gas introduction hole 6. The top ring 3 and the second ring 4 fit into first and second second ring grooves 2a and 2b formed in the piston 2, respectively. A space 7 is formed between the top ring 3 and the second ring 4. The land 16 between the ring grooves 2a and 2b is provided with a communication portion that communicates the ring grooves 2a and 2b with the top ring 3 in contact with the lower surface 17 of the ring groove 2a that has been moved away from the cylinder head 8. A certain communication hole 5 is formed.

FIG. 3 is a pressure diagram of the four-stroke diesel engine shown in FIGS. 1 and 2. FIG. Figure 2 1
As shown in , when the piston 2 is in the compression stroke and the crank angle is Θ1, the top ring 3 is in contact with the lower surface 17 of the ring groove 2a, and the combustion chamber 9
The compressed air inside passes through the communication hole 5 and fills the space 7. At this time, the gas introduction hole 6 is closed by the action of the high-pressure gas supply device 15.

FIG. 2 shows the state immediately before explosion in the combustion chamber 9, and before the piston 2 reaches top dead center. At this time, the high-pressure gas supply device 15 opens the gas introduction hole 6. High pressure gas is supplied to the space 7 after this crank angle Θ2. Pressure P1 in this space 7
is the pressure PZ in the cylinder before the explosive combustion begins
The top ring 3 is higher than the ring groove 2a.
It leaves the lower surface 17 of the ring groove 2a and comes into close contact with the upper surface 19 of the ring groove 2a. The pressure of the gas from the conduit 14 supplied to the gas introduction hole 6 is selected to be greater than the maximum cylinder pressure PZ1 at the crank angle Θ3.

At the crank angle Θ3, the piston 2 is on its downward stroke, as shown in FIG. 2, and the high pressure gas supply device 15 is closed. That is, the high-pressure gas supply device 15 cuts off the supply of high-pressure gas when the top ring 3 is farther away from the cylinder head 8 than the gas introduction hole 6. At this time, the pressure P1 in the space 7 is the cylinder internal pressure.
It is higher than PZ. Therefore, combustion gas does not enter the space 7 from the combustion chamber 9 via the piston top land 20 with the top ring 3 as a boundary.

FIG. 2 shows a state in which the piston 2 is at a position sufficiently lowered from the top dead center.

In this way, the space 7 is filled with clean gas, and combustion gas can be prevented from entering the top ring 3 of the piston 2 and the crank chamber below. This makes it possible to reduce abrasive wear between the piston ring and the cylinder liner caused by combustion residues and hard particles contained in the combustion gas. In this way, by introducing the compressed air during the compression stroke into the space 7 through the connecting hole 5, the amount of high-pressure gas introduced from the gas introduction hole 6 can be reduced as much as possible. Accordingly, the power of the compressor 11 can be reduced.

FIG. 4 is a sectional view of a part of another embodiment of the present invention, and FIG. 5 is a sectional view taken along the section line V-V. In this embodiment, a land 1 is formed between the top ring 3 and the second piston ring 4.
As clearly shown in FIG. 5, grooves 21 serving as communication portions are formed on the lower surface of the ring groove 2a of No. 6 at intervals in the circumferential direction. In this way, compressed air can be introduced into the space 7 through the communication path formed by the groove 21 during the compression stroke.

In the above-described embodiment, the land 16 of the piston 2 is provided with the communication hole 5 and the groove 21, but the top ring 3 is provided with such a communication hole and groove 21 to prevent compressed air from flowing into the space 7 during the compression stroke. You may also introduce it.

The invention can be implemented in connection with four-stroke as well as two-stroke internal combustion engines.

As described above, according to the present invention, gas having a pressure higher than the maximum pressure inside the cylinder is supplied to the space defined by the inner circumferential surface of the cylinder liner and the piston between the top ring and the second piston ring. By introducing this, it is possible to prevent combustion residues and hard particles from being interposed between the cylinder liner inner circumferential surface and the piston ring, thereby making it possible to prevent wear. Moreover, since the compressed air in the cylinder is introduced into the space during the compression stroke, the pressure in that space is at least approximately equal to that of the combustion chamber, and as a result, combustion residues, hard particles, etc. It is possible to prevent the gas from entering between the ring and the outer peripheral surface of the ring, and also to reduce the amount of gas supplied from the gas introduction hole, thereby reducing the power required to supply the gas. becomes possible.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the present invention, FIG. 2 is a sectional view of the vicinity of the top ring 3 and second piston ring 4, and FIG. 3 is a sectional view of the embodiment shown in FIGS. 4 is a sectional view of a part of another embodiment of the present invention, and FIG. 5 is a simplified sectional view taken along the section line V-V in FIG. 4. DESCRIPTION OF SYMBOLS 1... Cylinder liner, 2... Piston, 3... Top ring, 4... Second piston ring, 5... Communication hole, 6... Gas introduction hole, 16... Land, 21... Concave groove.

Claims (1)

[Claims] 1. A plurality of ring grooves are formed on the outer circumference of the piston at intervals in the axial direction, a piston ring is fitted into each ring groove, and the outer circumferential surface of these piston rings is connected to the cylinder liner. In a sealing device for an internal combustion engine configured to be in sliding contact with the inner peripheral surface of the cylinder liner, a gas introduction hole is formed in the cylinder liner to which high-pressure gas is supplied from the high-pressure gas supply device, and this high-pressure gas is The gas inlet hole has a pressure higher than the maximum pressure of the combustion chamber, and the gas introduction hole connects the top ring closest to the combustion chamber among the piston rings and the top ring during the period when the gas in the combustion chamber reaches the maximum pressure immediately before the explosion. and a second ring adjacent to the top ring, and the high pressure gas supply device is configured to supply high pressure gas when the top ring is further away from the cylinder head than the gas introduction hole. The top ring is inserted into the land between the first ring groove in which the top ring is fitted and the second ring groove in which the second ring is fitted in the ring groove. The first and second
A sealing device for an internal combustion engine, characterized in that a communication portion is formed that communicates a ring groove.