JPH07208178A - Turbo-cooling type two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the combustion efficiency as well as to improve the scav enging efficiency, by suppressing the flowing out of a fresh air together with an axhaust gas, in a turbocooling type two-cycle internal combustion engine in which a fresh air whose temperature is lowered by an air expanding machine is to be led in to a cylinder. CONSTITUTION:A scavenging chamber is divided into the first scavenging chamber 13 and the second scavenging chamber 5. In the former period of the scavenging period, a high temperature air at the outlet of the compressor 6 of an exhaust gas turbosupercharger 60 is led in from the first scavenging chamber 13 to a cylinder 1, and in the latter period, a low temperature air at the outlet of an air expanding machine 11 is led in to the cylinder 1 from the second scavenging chamber 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo-cooling two-cycle internal combustion engine such as a uniflow scavenging diesel engine.

[0002]

2. Description of the Related Art A conventional turbocooling two-cycle diesel engine supply / exhaust system is shown in FIG. In FIG. 2, 1 is a cylinder, 2 is a scavenging hole formed in the lower portion of the cylinder 1 at equal intervals along the circumferential direction, 3 is a piston, 4 is an exhaust valve, and 5 is a scavenging chamber.

Reference numeral 60 denotes an exhaust turbocharger, which is an exhaust turbine 7
And the compressor 6, the exhaust turbine 7 is driven by the exhaust gas supplied through the exhaust pipe line 21, and the air compressed by the compressor 6 coaxial with the exhaust turbine 7 is sent to the air cooler 8. .

Reference numeral 12 denotes an exhaust branch passage 22 branched from the exhaust pipe passage 21.
Is a second exhaust turbine driven by exhaust gas supplied through the exhaust gas, 9 is a second stage air cooler, and 11 is an air expander. The second exhaust turbine 12 is arranged coaxially with and drives the second-stage air compressor 9 and the air expander 11.

When the piston 3 approaches the bottom dead center, the exhaust valve 4
Is opened and the exhaust gas in the cylinder 1 flows out into the exhaust pipe line 21 through the exhaust valve 4. Further, when the piston 3 descends, the fresh air accumulated in the scavenging chamber 5 flows into the cylinder 1 through the scavenging holes 2, and the residual exhaust gas in the cylinder 1 is pushed out from the exhaust valve 4.

When the exhaust turbine 7 is rotationally driven by the exhaust gas, fresh air is sucked into the compressor 6 to be pressurized, cooled by the air cooler 8 and then further pressurized by the second-stage compressor 9,
It is cooled by the second stage air cooler 10. This air is expanded by the air expander 11 to perform work, so that the temperature is lowered and the air is introduced into the scavenging chamber 5.

[0007]

In the conventional turbo-cooling type two-cycle internal combustion engine described above, since the residual exhaust gas is pushed out by the fresh air filled in the cylinder 1, almost half of the fresh air is accumulated in the cylinder 1. Without exhaust pipe
It leaks to 21.

Therefore, not only the energy spent for obtaining the fresh air to be charged into the cylinder 1 is wasted but also the exhaust turbocharger 60, the air cooler 8, the second stage compressor 9 and the second stage are used. Stage air cooler 10, air expander 11 and second exhaust turbine
12 capacity needs to be increased. For this reason, there is a problem that the cost of the device required for supercharging and scavenging increases, and the exhaust energy also increases to reduce the efficiency of the engine.

The present invention requires less exhaust energy,
An object of the present invention is to provide a low-cost, high-performance turbo-cooling type two-cycle internal combustion engine.

[0010]

SUMMARY OF THE INVENTION The present invention has been invented to solve the above problems, and its gist is to provide an exhaust turbine rotatably driven by an exhaust gas of an engine 9 and the turbine. An exhaust turbocharger equipped with a compressor that is rotationally driven to compress air, a second-stage compressor that compresses the air sent from the compressor, and an air sent from the second-stage compressor. A turbo-cooling two-cycle internal combustion engine comprising an air cooler for cooling and an air expander for expanding the air cooled by the air cooler to lower the temperature and rotationally driving the second stage compressor. In the first scavenging chamber, the first scavenging chamber and the second scavenging chamber selectively communicated with the scavenging hole formed in the cylinder, and the first scavenging chamber branched from the air outlet of the compressor of the exhaust turbocharger. A high temperature air passage connected to the air expander, a low temperature air passage connecting the air outlet of the air expander and the second scavenging chamber, and the second scavenging chamber in a period before a certain period during the scavenging and exhausting period of the engine. And the scavenging hole are cut off from each other
A scavenging switching valve that connects the scavenging chamber and the scavenging hole, and blocks the first scavenging chamber and the scavenging hole to connect the second scavenging chamber and the scavenging hole in a later period after the certain period of time. And a turbo-cooling type two-cycle internal combustion engine.

The second stage compressor and the air expander can be rotationally driven by a second exhaust turbine which is arranged coaxially therewith and which is driven by the exhaust gas of the engine.

[0012]

In the present invention, the first period is set in the first half of the sweeping period.
Since the scavenging chamber and the scavenging hole communicate with each other, high-temperature air from the air outlet of the compressor of the exhaust turbocharger is introduced into the cylinder. In the latter half of the scavenging period, the second scavenging chamber communicates with the scavenging hole, so that low-temperature air from the air outlet of the air expander is introduced into the cylinder.

[0013]

1 shows a scavenging / exhaust system of a turbo-cooling type two-cycle internal combustion engine according to an embodiment of the present invention.
In FIG. 1, 1 is a cylinder, 2 is a scavenging hole, 3 is a piston, 4 is an exhaust valve, 21 is an exhaust pipe line, 60 is an exhaust turbocharger, 8 is an air cooler, 9 is a second stage compressor, 10 is a second stage air cooler, 11 is an air expander, 12 is a second exhaust turbine, 22
Is an exhaust branch passage, and the above is the same as the conventional one shown in FIG.

The scavenging chamber is divided into a first scavenging chamber 13 and a second scavenging chamber 5 along the axial direction of the cylinder 1. Reference numeral 14 is a switching valve for switching the communication between the first scavenging chamber 13, the second scavenging chamber 5 and the scavenging hole 2, and 15 is a hydraulic cylinder for driving the switching valve 14.

The hot air passage 31 branched from the air outlet of the compressor 6 of the exhaust turbocharger 60 is connected to the first scavenging chamber 13, and the air outlet of the air expander 11 is passed through the low temperature air passage 32. Connected to the second scavenging chamber 5.

When the piston 3 descends and the exhaust valve 4 opens, the exhaust gas in the cylinder 1 drives the exhaust turbine 7 of the exhaust turbocharger 60, and the compressor 6 draws the air sucked from the atmosphere. Compress and discharge. Most of the hot compressed air discharged from the compressor 6 is sent to the air cooler 8 where it is cooled, and part of it is sent to the first scavenging chamber 13 via the hot air passage 31.

On the other hand, the air cooled by the air cooler 8 is further pressurized by the second stage compressor 9, then cooled by the second stage air cooler 10 and then sent to the air expander 11. To be The air expander 11 expands the introduced air to lower the temperature, and supplies drive energy to the second stage compressor 9 by this expansion work. Then, the low temperature fresh air cooled by the air expander 11 is sent to the second scavenging chamber 5 through the low temperature air pipe 32.

After the piston 3 moves up to open the scavenging hole 2, that is, after the start of the scavenging and exhausting period of the engine, the switching valve 14 is driven by the hydraulic cylinder 15 until a certain period of time.
The first scavenging chamber 13 and the scavenging hole 2 communicate with each other. Then, fresh air having a large volume per unit weight at a high temperature in the first scavenging chamber 13 flows into the cylinder 1 through the scavenging holes 2, and the exhaust gas remaining in the cylinder 1 is exhausted by the exhaust valve 4
Since it is pushed out into the exhaust pipe line 21 through, the high scavenging efficiency is obtained.

After the scavenging period, that is, when a certain period of time elapses, the switching valve 14 is driven by the hydraulic cylinder 15 to switch to the position indicated by the solid line in FIG. 1, and the second scavenging chamber 5 and the scavenging hole 2 are moved. And can communicate with each other. As a result, the fresh air having a large weight per unit volume at a low temperature in the second scavenging chamber 5 is filled in the cylinder 1, so that the combustion efficiency of the engine is improved and a high output can be realized.

[0020]

According to the present invention, the exhaust gas can be pushed out by the fresh air having a large specific volume during the period before the exhaust gas scavenging period until a certain time, so that a high scavenging efficiency can be obtained.

Further, since the fresh air having a low specific gravity at a low temperature is charged into the cylinder in a later period after a certain period of time, it is possible to prevent the fresh air from being discharged together with the exhaust gas. Since this fresh air is used for combustion, the combustion efficiency of the engine is improved and a high output can be obtained.

[Brief description of drawings]

FIG. 1 is a system diagram showing a scavenging exhaust system of a turbo-cooling two-cycle internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a system diagram showing a scavenging exhaust system of a conventional turbo-cooling two-cycle internal combustion engine.

[Explanation of symbols]

 1 Cylinder 2 Scavenging hole 3 Piston 4 Exhaust valve 13 First scavenging chamber 5 Second scavenging chamber 60 Exhaust turbocharger 7 Exhaust turbine 6 Compressor 8 Air cooler 9 Second stage compressor 10 Second stage air cooler 11 Air expander 12 Second exhaust turbine 14 Switching valve 15 Hydraulic cylinder 21 Exhaust pipe 32 Low temperature air passage 31 High temperature air passage

Claims (2)

[Claims] 1. An exhaust turbocharger comprising an exhaust turbine which is rotationally driven by exhaust gas of an engine and a compressor which is rotationally driven by this turbine to compress air, and air sent from the compressor is compressed. A second stage compressor, an air cooler that cools the air sent from the second stage compressor, the temperature of the air cooled by the air cooler is expanded, and the second stage compressor is used. In a turbo-cooling type two-cycle internal combustion engine including an air expander that rotationally drives the machine, a first scavenging chamber and a second scavenging chamber that are selectively communicated with a scavenging hole formed in a cylinder, and the exhaust gas A high temperature air path branched from the air outlet of the compressor of the turbocharger and connected to the first scavenging chamber; a low temperature air path connecting the air outlet of the air expander and the second scavenging chamber; The second scavenging chamber and the scavenging hole are cut off in the previous period until a certain time during the scavenging / exhaust period of the seki to allow the first scavenging chamber and the scavenging hole to communicate with each other, and the subsequent period after the certain time A turbo-cooling type two-cycle internal combustion engine, comprising: a scavenging switching valve that shuts off the first scavenging chamber and the scavenging hole to connect the second scavenging chamber and the scavenging hole. 2. The second exhaust compressor and the air expander are rotatably driven by a second exhaust turbine which is arranged coaxially with the second compressor and is driven by the exhaust gas of the engine. The described turbo-cooling two-cycle internal combustion engine.