JPS61160522A - Scavenge pump device in uniflow engine - Google Patents

Abstract

PURPOSE:To obtain a high scavenge pressure even if an auxiliary motor blower is eliminated, by utilizing a scavenge valve which slides on the inner surface of an engine cylinder and opens and closes scavenge holes, and a scavenge pump chamber in which a partition wall is provided in a scavenge sump so that a closed space is defined below the piston. CONSTITUTION:When the load of an engine is below 50%, a valve 54 is opened while a discharge valve 56 is closed to introduce high pressure air into an air cylinder 52 so that an air piston 53 serves as an air spring 53. As a piston 17 ascends, scavenge air is introduced from a scavenge air inlet chamber 41 into a scavenge air pump chamber 42 through a check valve 44. A scavenge port 12 is closed by a scavenge port valve 51. When a piston 17 descends, pressure in a scavenge chamber 42 increases so that scavenge air flows from the scavenge air pump chamber 42 into a scavenge air pump 19 through a check valve 45. Further, the piston 17 lowers to depress the scavenge port valve 51 overcoming the air piston 53 so that scavenge air flows into the cylinder through scavenge holes 12. When the load of the engine is above 60%, high pressure air in the air cylinder 52 is discharged so that the same scavenge operation is carried out as that in conventional engines.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a scavenging pump device for a uniflow engine.

[Conventional technology]

Figure 3 shows the structure of a conventional cross engine, which is a V-type two-stroke engine and has a uniflow scavenging type. In the figure, a cylinder jacket 11 supports a cylinder liner 13 having scavenging holes 12 in its lower part, and a cylinder cover 5 having an exhaust valve 14 is placed thereon.

A piston 17 supported by a piston rod 16 slides on the inner surface of the cylinder liner 13. The base of the piston rod 16 is supported by a cross member 18, and drives a crankshaft 22. A scavenging air reservoir 19 is provided in the lower part of the cylinder jacket 11 to supply scavenging air to the scavenging hole 12. Cylinder cover 5. A combustion chamber 21 is formed by the cylinder liner 13 and the piston 17. The working gas in the combustion chamber 21 flows out to the exhaust valve 23 when the exhaust valve 14 is opened, and the working gas flows out to the exhaust valve 23. After driving the exhaust turbine 31 of the supercharger 30, it is released into the atmosphere. The exhaust turbine 31 has a coaxial compressor 32
rotates to compress the atmosphere and create high-temperature, high-pressure scavenging air. The high-temperature, high-pressure scavenging air is cooled by an air cooler 33, then pressurized by a centrifugal auxiliary blower 34 driven by an electric motor, and then supplied to the scavenging reservoir I9.

Fuel is injected into the combustion chamber 21 from a fuel injection valve (not shown) and combusted to make the working gas high temperature and pressure.

Thereafter, the piston 17 descends as the crankshaft 22 rotates, and the working gas expands, transmitting work to the piston 17.

When the piston 17 approaches bottom dead center.

First, exhaust valve] 4 opens and high-temperature, high-pressure working gas flows into exhaust pipe 2.
3 and drives the exhaust turbine 31, the pressure in the cylinder liner 13 decreases and becomes lower than the scavenging pressure in the exhaust reservoir 19. At this time, the histones 17 open the scavenging holes 12, so scavenging air flows into the cylinder liner 13, pushes out the combusted working gas from the exhaust valve 14, and fills the cylinder liner 13 with new air. crankshaft 2
2, the piston 17 begins to rise and closes the scavenging hole 12, and the exhaust valve I4 also closes to begin the compression stroke.

By the way, when the engine load is 60 inches or more, the exhaust turbine 31
The output of the auxiliary blower 34 in Fig. 3 becomes sufficiently large.
High scavenging pressure can be obtained without driving. As a result, the pressure within the cylinder liner 13 at the beginning of compression is high and sufficient fresh air is secured within the cylinder liner 13.

However, when the engine load falls below 50%, the auxiliary blower 34
If the exhaust turbine 31 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 degree Tv of the lower surface of the exhaust valve 14 on the combustion chamber 21 side exceeds 600° C., causing problems such as blow-out of the exhaust valve 14. Therefore, when the load is less than 50%, the auxiliary blower 34 is driven to increase the scavenging pressure, and the TV is lowered as shown by the dashed line in FIG. 4 to prevent problems from occurring.

[Problem that the invention seeks to solve]

The above has the following drawbacks.

When the engine load is less than 50%, an auxiliary blower 34 device is required. Furthermore, in order to obtain electric power for driving the auxiliary blower 34, a power generation set is required to generate the electric power.

[Means for solving problems]

An object of the present invention is to focus on the above points and provide a scavenging pump device that eliminates the electric auxiliary blower device, and is characterized by opening and closing the scavenging hole by sliding on the inner surface of the cylinder liner. A cylindrical scavenging hole valve and a scavenging chamber are provided in which a partition is provided in the scavenging reservoir so that the lower side of the piston becomes a sealed space when the scavenging hole valve closes the exhaust hole.

[For production]

In this case, when the load of the two engines is 50% or less, the lower side of the piston serves as the scavenging pump, so high scavenging pressure can be obtained even if the electric auxiliary blower of the conventional device is omitted.

〔Example〕

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

FIG. 1 is a cross-sectional view of one embodiment of the device according to the present invention.

In the figure, a partition wall is installed at the bottom of the scavenging groove 9 to provide a scavenging inlet chamber 41 and a scavenging pump chamber 42.

Check valves 43 and 44 are provided between the scavenging inlet chamber 41 and the scavenging groove 19 and between the scavenging inlet chamber 41 and the scavenging inlet chamber 42, respectively.

A check valve 45 and a rotary gate valve 46 are provided between the scavenging pump chamber 42 and the scavenging groove 19. Scavenging air from the air cooler 33 is first made to flow into the scavenging air inlet chamber 41 .

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

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

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 circumference of the piston 17.

The operation in the case of the above configuration will be described.

When the engine load is less than 50 inches, valve 54 in FIG.
When the release valve 56 is opened and the discharge valve 56 is closed, high pressure air flows into the air cylinder 52, high pressure acts on the air piston 53, and the air piston 53 becomes an air spring. Also at this time 1
Rotary gate valve 46 is closed as shown.

When the piston 17 begins to rise above the bottom dead center, the pressure in the scavenging pump chamber 42 decreases, so scavenging air flows from the scavenging inlet chamber 41 through the check valve 44.

At this time, the scavenging petal 51 rises due to the force of the air piston 53 as the piston 17 rises, and closes the scavenging hole 12. At this point, the air piston 53 reaches the upper limit of its stroke and stops, so the scavenging hole 12 remains closed. The piston 17 further rises, and the fuel is combusted and expanded within the combustion chamber 21.

When the piston 17 begins to descend during the expansion stroke.

Since the scavenging hole 12 is closed, the pressure within the scavenging pump chamber 42 begins to rise. As a result, scavenging air begins to flow from the scavenging pump chamber 42 into the scavenging groove 19 through the check valve 45, and the pressure within the scavenging groove 19 increases.

When the piston 17 further descends, the lower end of the outer circumference of the piston 17 comes into contact with the upper end of the scavenging petal 51.

The scavenging petal 51 is pushed down against the force of the air piston 53. As a result, the same scavenging effect as in the conventional device is performed. As described above, the lower side of the piston 17 serves as a scavenging air I, which increases the pressure of the scavenging air from the 9-order cooler 33 and supplies it to the scavenging groove 19.

When the engine load is 60% or more, valve 5 in Fig.
4 and open the discharge valve 56. the result.

The high-pressure air in the air reservoir 55 and the air cylinder 52 is released to the atmosphere from the release valve 56 and the pressure decreases, so the scavenging petal 51 remains at the bottom dead center of the piston I7, making it impossible to close the scavenging hole. do not have. Further, as shown in FIG. 2, the rotary gate valve 46 is opened. As a result, scavenging air from the air cooler 33 is directly supplied to the scavenging groove 19 from the scavenging inlet chamber 41 through the check valve 43 to perform scavenging action, as in the conventional device.

〔Effect of the invention〕

The above case has the following effects.

When the engine load is less than 50 inches, the lower side of the male stone 17 becomes the scavenging pump, so high scavenging pressure can be obtained even if the electric auxiliary blower of the conventional device is omitted, as shown by the solid line C in Fig. 4. The temperature T of the lower surface of the exhaust valve 14 does not exceed 600°C. As a result, the power generation set conventionally required for driving the auxiliary blower can also be omitted.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the device according to the present invention, Fig. 2 is an explanatory view showing the situation when the piston is at the bottom dead center, and Fig. 3 is a conventional uniflow scavenging crosshead type two-cycle A sectional view showing the engine. FIG. 4 is a diagram showing changes in the temperature TV of the lower surface of the exhaust valve on the combustion chamber side. 12...Scavenging hole, 13...Cylinder liner, 17.
...Piston, 19...Scavenging groove, 42...Scavenging pump chamber. 51...Scavenging petals. Figure 1 Section 2% 3 Figure

Claims (1)

[Claims] 1. In a uniflow scavenging crosshead type two-cycle engine, a cylindrical scavenging hole valve slides on the inner surface of the cylinder liner to open and close the scavenging hole, and a partition is provided in the scavenging reservoir so that the scavenging hole valve closes the scavenging hole. A scavenging pump device for a uniflow engine, characterized by having a scavenging pump chamber in which the lower side of the piston becomes a sealed space when the piston is closed.