JPH063141B2 - Uniflo engine scavenging pump device - Google Patents

Description

The present invention relates to a scavenging pump device for a uniflow engine.

[Conventional technology]

FIG. 3 shows a structure of a conventional crosshead type two-cycle engine and a uniflow scavenging type. In the figure, a cylinder jacket 11 supports a cylinder liner 13 having a scavenging hole 12 at its lower part, and a cylinder cover 15 having an exhaust valve 14 is mounted thereon. The piston 17 supported by the piston rod 16 slides on the inner surface of the cylinder liner 13.
The lower end of the piston rod 16 is supported by the crosshead 18 and drives the crankshaft 22. A scavenging reservoir 19 for supplying scavenging air to the scavenging holes 12 is provided below the cylinder jacket 11. Cylinder cover 15, cylinder liner 1
A combustion chamber 21 is formed by 3 and the piston 17. Combustion chamber 2
The working gas in 1 is exhausted along with the opening of the exhaust valve 14 and the exhaust pipe 23.
And is discharged to the atmosphere after driving the exhaust turbine 31 of the exhaust turbocharger 30. The exhaust turbine 31 rotates a coaxial compressor 32 to compress the atmosphere and generate high temperature and high pressure scavenging air. The high-temperature, high-pressure scavenging air is cooled by the air cooler 33, then pressurized by the centrifugal auxiliary blower 34 driven by the electric motor, and supplied to the scavenging reservoir 19.

Fuel is injected into the combustion chamber 21 from a combustion injection valve (not shown) and burned to make the working gas high temperature and high pressure. After that, the piston 17 descends in accordance with the rotation of the crankshaft 22 and the working gas expands, and transmits the work to the piston 17. When the piston 17 approaches the bottom dead center, first, the exhaust valve 14 opens and high-temperature, high-pressure working gas is discharged to the exhaust pipe 23 to drive the exhaust turbine 31, and the pressure in the cylinder liner 13 decreases.
It becomes lower than the scavenging pressure in the exhaust reservoir 19. At this time, since the piston 17 opens the scavenging hole 12, the scavenging gas flows into the cylinder liner 13 to push out the burned working gas from the exhaust valve 14 and fill the cylinder liner 13 with new air. When the bottom dead center is passed by the rotation of the crankshaft 22, the piston 17 starts to rise and closes the scavenging hole 12, and also closes the exhaust valve 14 to start the compression stroke.

By the way, when the engine load is 60% or more, the exhaust turbine 31
Output of the auxiliary blower 34 shown in FIG.
A high scavenging pressure can be obtained without driving. As a result, the pressure in the cylinder liner 13 at the beginning of compression is increased and sufficient new air is secured in the cylinder liner 13.

However, when the engine load is 50% or less, the auxiliary blower 34
If the engine is not driven, the output of the exhaust turbine 31 will be insufficient,
The scavenging pressure becomes low, and sufficient new air cannot be secured in the cylinder liner 13 at the beginning of compression. As a result, as shown by the broken line a in FIG. 4, the temperature T _v of the lower surface of the exhaust valve 14 on the combustion chamber 21 side exceeds 600 ° C., and problems such as blowout of the exhaust valve 14 occur. Therefore, when the load is 50% or less, the auxiliary blower 34 is driven to increase the scavenging pressure, and T _v is lowered as shown by the one-dot chain line b in FIG. 4 to prevent the occurrence of trouble.

[Problems to be solved by the invention]

 The above has the following drawbacks.

When the engine load is 50% or less, the auxiliary blower 34 device is required. Further, in order to obtain electric power for driving the auxiliary blower 34, a power generation set that generates the electric power is required.

[Means for solving problems]

In view of the above points, an object of the present invention is to provide a scavenging pump device without an electric auxiliary blower device, which is characterized in that the lower end open part of the cylinder liner and the lower part of the cylinder liner are cleaned. A uniflow that supplies scavenging gas pressurized by a compressor driven by an exhaust turbine to a scavenging reservoir surrounding the pores, and in the lower part of the scavenging reservoir, a lower end opening of the cylinder liner and a scavenging hole are separated from each other. Forming a scavenging pump chamber for supplying scavenging air, and two check valves opened from the scavenging inlet chamber toward the scavenging reservoir upper part and the scavenging pump chamber, and the scavenging reservoir from the scavenging pump chamber. A check valve that opens toward the upper part, a sluice valve between the scavenging pump chamber and the upper part of the scavenging reservoir, a scavenging hole valve that slides on the inner surface of the cylinder liner to open and close the scavenging hole, and the scavenging hole valve. Drive A control mechanism is provided, and when the load is low, the sluice valve is closed, the scavenging hole valve is held at the upper scavenging hole closing position and can be pushed down by the piston in the cylinder liner, and when the load is high, the scavenging valve is opened. The scavenging hole valve is configured to be held at the lower scavenging hole opening position.

[Action]

In this case, when the engine load is 50% or less, the lower side of the piston is the scavenging pump, so that a high scavenging pressure can be obtained without the electric auxiliary blower of the conventional device.

〔Example〕

Embodiments according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an apparatus according to one embodiment of the present invention.

In the figure, a partition is installed below the scavenging reservoir 19 to provide a scavenging inlet chamber 41 and a scavenging pump chamber 42. Scavenging inlet chamber 41
And the scavenging reservoir 19 and the scavenging inlet chamber 41 and the scavenging pump chamber 4
Check valves 43 and 44 are provided between the two.

A check valve 45 and a rotary sluice valve 46 are provided between the scavenging pump chamber 42 and the scavenging reservoir 19. Scavenging air from the air cooler 33 first flows into the scavenging inlet chamber 41.

A cylindrical scavenging hole valve 51 that slides on the inner surface of the cylinder liner 13 and can close the scavenging hole 12 is provided.

The scavenging hole valve 51 is driven by an air piston (53) sliding in an air cylinder 52. High-pressure air from an air source (not shown) is supplied to the air cylinder 52 through a valve 54. An air reservoir 55 and a discharge valve 56 are provided between the valve 54 and the air cylinder 52.

FIG. 2 shows the situation when the piston 17 reaches the bottom dead center.

The scavenging hole valve 51 is housed outside the lower part of the piston 17, and the upper part of the scavenging hole valve 51 is in close contact with the lower end of the outer periphery of the piston 17.

The operation of the above configuration will be described.

When the engine load is 50% or less, the valve 54 in FIG.
When the valve is opened and the discharge valve 56 is closed, high-pressure air flows into the air cylinder 52, a high pressure acts on the air piston 53, and the air piston 53 becomes an air spring. At this time, the rotary sluice valve 46 is closed as shown.

Here, when the piston 17 starts to rise from the bottom dead center, the pressure in the scavenging pump chamber 42 decreases, so that the scavenging gas flows from the scavenging gas inlet chamber 41 through the check valve 44. At this time, the scavenging hole valve 51 rises due to the force of the air piston 53 as the piston 17 rises, and closes the scavenging hole 12. Here, the air piston 53 reaches the upper limit of its stroke and stops, so that the scavenging hole 12
Remains closed. Further, the piston 17 rises, and the combustion and expansion of the fuel occur in the combustion chamber 21.

When the piston 17 begins to descend in the expansion stroke, the pressure inside the scavenging pump chamber 42 begins to rise because the scavenging hole 12 is closed. As a result, scavenging gas begins to flow from the scavenging pump chamber 42 into the scavenging reservoir 19 through the check valve 45, and the scavenging reservoir 1
The pressure in 9 rises.

When the piston 17 further descends, the lower end of the outer periphery of the piston 17 comes into contact with the upper end of the scavenging hole valve 51, and the air piston 53
The scavenging hole valve 51 is pushed down against the force of. As a result, the same scavenging action as the conventional device is performed. As described above, the lower side of the piston 17 serves as a scavenging pump, which acts to increase the pressure of the scavenging air from the air cooler 33 and supply it to the scavenging reservoir 19.

When the engine load is 60% or more, the valve 5
4 is closed and the discharge valve 56 is opened. As a result, the high pressure air in the air reservoir 55 and the air cylinder 52 is discharged to the atmosphere from the discharge valve 56, and the pressure drops, so that the scavenging hole valve 51 remains at the position of the bottom dead center of the piston 17 and the scavenging hole. Never close. Further, as shown in FIG. 2, the rotary sluice valve 46 is opened. As a result, in the scavenging reservoir 19, the scavenging air from the air cooler 33 is directly supplied from the scavenging inlet chamber 41 through the check valve 43 as in the conventional device to perform the scavenging action.

〔The invention's effect〕

 In the above case, there are the following effects.

When the engine load is 50% or less, the lower side of the piston 17 becomes a scavenging pump, so a high scavenging pressure can be obtained even if the electric auxiliary blower of the conventional device is omitted, and as shown by the solid line c in FIG. The temperature T _v of the lower surface of the valve 14 does not exceed 600 ° C. As a result, it is possible to omit the power generation set that was conventionally required to drive the auxiliary blower.

[Brief description of drawings]

FIG. 1 is a sectional view showing an apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory view showing a situation when a piston is at bottom dead center, and FIG. 3 is a conventional uniflow scavenging crosshead type 2
FIG. 4 is a cross-sectional view showing the cycle engine, and FIG. 4 is a diagram showing a change in the temperature T _v of the lower surface of the exhaust valve on the combustion chamber side. 12 ... scavenging hole, 13 ... cylinder liner, 17 ... piston, 19 ... scavenging reservoir, 42 ... scavenging pump chamber, 51 ... scavenging hole valve.

Continuation of front page (56) Reference JP-A-57-151020 (JP, A) JP-A-55-125318 (JP, A) JP-B 32-9658 (JP, B1)

Claims (1)

[Claims] A uniflow engine for supplying scavenging gas pressurized by a compressor driven by an exhaust turbine to a scavenging tank surrounding a lower end open portion of the cylinder liner and a scavenging hole at a lower portion of the cylinder liner. At the bottom of
A scavenging pump chamber that separates the lower end opening portion of the cylinder liner from the scavenging hole, and a scavenging inlet chamber that receives scavenging gas are formed, and the scavenging inlet chamber is opened toward the scavenging reservoir upper portion and the scavenging pump chamber. Two check valves, a check valve that opens from the scavenging pump chamber toward the upper part of the scavenging reservoir, a sluice valve between the scavenging pump chamber and the upper part of the scavenging reservoir, and a slide valve on the inner surface of the cylinder liner. A scavenging hole valve that opens and closes the scavenging hole and a drive control mechanism for the scavenging hole valve are provided, and when the load is low, the sluice valve is closed, and the scavenging hole valve is pushed down to the upper scavenging hole closing position and by the piston in the cylinder liner. Hold possible and
A scavenging pump device for a uniflow engine, characterized in that, at the time of high load, the sluice valve is opened and the scavenging hole valve is held at a lower scavenging hole opening position.