JP2738039B2 - 2-cycle insulated engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a two-cycle insulated engine provided with a turbocharger.

[Conventional technology]

2. Description of the Related Art Conventionally, a heat insulating engine in which a ceramic liner head having an upper portion of a cylinder liner is fitted inside a cylinder head is disclosed in, for example, JP-A-59-122765.

Also, in a conventional two-stroke engine, a crank chamber is provided with a compressor function to introduce intake air into a combustion chamber, and an exhaust valve is disposed in an exhaust port formed in a cylinder head. Exhaust holes are provided in the cylinder, and scavenging holes are provided on the entire circumference under the cylinder liner to prevent scavenging and exhaust gas from becoming disturbed, increase scavenging efficiency and intake efficiency, and perform asymmetric scavenging and rear intake. There is a uniflow scavenging type that can be used.

Generally, the operation of a gasoline engine or a diesel engine is performed by repeating four operations of an intake process, a compression process, a combustion process, and an exhaust process. In each of the processes, power is generated and torque is applied to a crankshaft. Only the combustion process is performed, and the other three processes are performed by inertia. There are two types of operating principles of each of these processes, a four-stroke engine and a two-stroke engine. In a two-stroke engine, an intake process and an exhaust process are performed in a part of a combustion process and a compression process, and a piston is operated. , Ie, one cycle is completed by one rotation of the crankshaft.

[Problems to be solved by the invention]

By the way, with respect to an insulated engine in which a combustion chamber formed of a cylinder formed in a cylinder head and a cylinder block is formed of an insulating material, a ceramic material, or the like in an insulating structure, volumetric efficiency is reduced due to high heat in the cylinder, and output is reduced. . The reason is that the cylinder head and the upper part of the cylinder are insulated, so the upper part of the combustion chamber and the wall surface are hot, and the fresh air sucked into the cylinder receives heat from the cylinder or the wall surface and expands by heating. Volumetric efficiency is reduced, and the amount of intake air sucked into the combustion chamber under the influence of the high-temperature wall surface is reduced to more than 20%.

Further, in an engine of a two-cycle operation, when air is exchanged, when an exhaust valve is opened and exhaust is performed through an exhaust port, a pressure wave, that is, a pulse wave is generated in the cylinder, and the exhaust gas is pushed out. As a result, fresh air flows into the negative pressure zone generated downstream of the exhaust gas from the lower part of the cylinder, but since the lower part of the cylinder is not so hot compared to the cylinder head, the fresh air is Insensitive to wall temperature. This is particularly advantageous in a two-cycle adiabatic engine, in which the amount of scavenged air or the amount of intake air does not decrease if fresh air is sucked from the lower part of the cylinder.

However, a two-cycle engine is not limited to an engine having heat insulation, and it is extremely difficult to stably supply intake air at a low speed of the engine. At the time of startup, the engine does not rotate continuously unless the scavenging is performed by blowing compressed air into the combustion chamber. Therefore, there is a method of obtaining a boost pressure by connecting a supercharger such as a turbocharger to an exhaust pipe.However, when the engine is running at a low speed, the air pressure sent from the compressor of the turbocharger is lower than the exhaust pressure of the engine. Good operating conditions cannot be obtained. Therefore, it is conceivable to make a conventionally used crank chamber function as a compressor, feed turbocharged air into the crank chamber, and send compressed air present in the crank chamber to the combustion chamber through an intake port. However, when a high boost pressure is applied to the piston during the downward stroke of the piston, there is a problem that the negative work increases.

An object of the present invention is to solve the above-described problem. In an insulated engine in which a combustion chamber including a cylinder head and a cylinder is configured to have an insulated structure, the temperature of a cylinder head portion becomes high, but a lower portion of the cylinder farther from the cylinder head is provided. Considering that the temperature is not relatively high, in the adiabatic engine, the intake port is provided at the lower part of the cylinder separated from the exhaust port to perform two-cycle operation, thereby improving the intake efficiency. When the engine is at low speed, the turbocharger does not have a function of feeding intake air, so that the crank chamber functions as a compressor to send compressed air from the crank chamber to the combustion chamber. Since the exhaust gas energy is high in an insulated engine, the turbocharger is strong. As the air pressure delivered from the compressor rises, the intake system is configured as a compound supercharged type so that the air from the turbocharger is delivered to the combustion chamber. In addition, the intake efficiency is improved in all areas to secure sufficient intake air volume, prevent exhaust gas from flowing back into the intake system, and minimize the thermal effects of exhaust gas and high-temperature walls on intake air. To provide a two-cycle insulated engine that can prevent a decrease in the amount of intake air and obtain a high output of the engine.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a cylinder head lower surface part and an upper part of a cylinder liner configured in a heat insulating structure, an exhaust valve arranged in a cylinder head, an intake port formed in a lower part of a cylinder liner, a first check valve communicating the outside with a crank chamber, A second check valve provided in a first intake passage communicating the crank chamber with the intake port, and a third check valve provided in a second intake passage communicating an air outlet of a compressor of a turbocharger with the intake port. The invention relates to a two-cycle adiabatic engine comprising valves.

[Action]

The two-stroke adiabatic engine according to the present invention is configured as described above and operates as follows. That is, the two-cycle insulated engine has an intake port formed below the cylinder liner, a first check valve that communicates outside air to the crank chamber, and a second check valve that is provided in a first intake passage that communicates the crank chamber to the intake port. When the engine is running at low speed, the engine exhaust gas volume is small, the air pressure sent from the compressor of the turbocharger installed in the engine is low, and the air flow is almost stopped because the engine is configured with a check valve Opening the first check valve by the upward stroke of the piston, sucking air into the crank chamber from outside air, closing the first check valve and opening the second check valve by the downward stroke of the piston, The air in the crank chamber is pushed into the combustion chamber through the first intake passage to secure an intake air amount at a low engine speed. At this time, the first communication with the turbocharger is performed.
Since the air pressure in the intake passage is low, the third check valve is closed.

Further, since the two-cycle adiabatic engine is configured by the third check valve provided in the second intake passage communicating the air outlet of the compressor of the turbocharger with the intake port,
When the engine rotates at a high speed, the intake air amount from the crank chamber alone becomes insufficient, so the intake air is taken from the turbocharger. That is,
In an adiabatic engine, in particular, the exhaust gas energy exhausted from the engine is considerably high, so that the turbocharger operates strongly, the boost pressure of the turbocharger increases, and the compression of the turbocharger from the compressor is reduced. The air, that is, the intake air, opens the third check valve and is strongly pushed into the combustion chamber from the second intake passage.

Thus, if the turbocharger is provided for the engine, the intake air can be sufficiently supplied into the combustion chamber. Moreover, compared to the supercharger, the turbocharger has extremely good torque characteristics in the high-speed rotation region,
As described above, if the intake air is actively fed into the combustion chamber in the high-speed region of the engine, an extremely good fuel condition can be secured.

〔Example〕

Hereinafter, an embodiment of a two-cycle adiabatic engine according to the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a two-cycle adiabatic engine according to the present invention. In this two-cycle insulated engine, a turbocharger is provided in the engine, and the intake function of the turbocharger feeds intake air into the combustion chamber when the engine is at a high speed, and makes the crank chamber function as a compressor when the engine is at a low speed to secure an intake air amount. In this case, the intake efficiency is improved in the entire operation range. In this two-cycle insulated engine, the cylinder head 3
A uniflow scavenging type having a large number of intake ports 20 in the circumferential direction below the cylinder liner 4 in which the exhaust valve 1 is disposed, and the scavenging action is performed by airflow in a certain direction with respect to the cylinder center line. It is a thing.

In this two-cycle insulated engine, the cylinder head 3 is fixed to the cylinder block 6 via a gasket 22, and the cylinder head lower surface 5 and the cylinder liner upper 9
The headliner is an insulated gasket
It is fitted and attached to the cylinder head 3 with a 10 interposed. This headliner constitutes the upper part of the combustion chamber 8 and is made of a ceramic material such as nitrogen silicon (Si ₃ N ₄ ) or silicon carbide (SiC), and has particularly heat resistance. The heat insulating gasket 10 is manufactured from a heat insulating material such as aluminum titanate and potassium titanate, and is disposed on the outer surface of the headliner. An exhaust port 28 formed in the lower surface 5 of the cylinder head having a heat insulating structure has a valve seat.
The exhaust port 28 communicates with the exhaust port 2 formed in the cylinder head 3. The exhaust valve 1 is disposed on the valve seat 24 disposed on the lower surface 5 of the cylinder head. Further, the exhaust port 2 is a turbocharger.
It communicates with the turbine scroll 29 of the turbine in FIG. Accordingly, the exhaust gas energy from the engine acts on the turbine of the turbocharger 11, transmits the rotation of the turbine to the compressor 25, and the compressed air sent out from the air outlet 26 of the compressor 25 by the operation of the compressor 25 is the second air. It is configured so that it can be sucked into the combustion chamber 8 through the intake passage 12.

Further, the cylinder liner 4 is fitted to the cylinder 23 formed on the cylinder block 6. A heat insulating gasket 21 made of a heat insulating material is interposed between the upper portion 9 of the cylinder liner and the cylinder liner 4 to prevent the heat of the upper portion 9 of the cylinder liner from being transmitted to the cylinder liner 4. The combustion chamber 8 is a chamber formed by being surrounded by the head liner including the cylinder head lower surface 5 and the cylinder liner upper portion 9, the cylinder liner 4 and the piston 7. Further, a crankcase 27 is formed by the crankcase 16 below the cylinder block 6. The piston 7, which reciprocates in the cylinder, that is, the cylinder liner 4, is not shown, but it is a matter of course that the heat insulating material and the ceramic material can be used to form a heat insulating structure.

In this two-cycle insulated engine, a circumferential annular intake port 18 is formed in a lower inner peripheral portion of the cylinder block 6 so as to face an intake port 20 formed in the cylinder liner 4. Further, in order to introduce intake air into the intake port 18, a first intake passage 17 communicating the crank chamber 27 with the intake port 18 and a second intake passage 17 communicating the intake outlet 26 of the compressor 25 of the turbocharger 11 with the intake port 18. An intake passage 12 is provided. The crankcase 27 is a crankcase
A first check valve formed of a reed valve or the like to prevent the compressed air in the crank chamber 27 from flowing back to the outside air. 15 are provided. The first intake passage 17 is provided with a second check valve 14 including a reed valve or the like in order to prevent the compressed air in the intake port 18 from flowing back to the crank chamber 27.

Further, the air outlet 26 of the compressor 25 of the turbocharger 11 provided in the engine is connected to the intake port 18 through the second intake passage 12. In the second intake passage 12,
In order to prevent the compressed air in the intake port 18 from flowing back to the air delivery passage side of the compressor 25 of the turbocharger 11, a third check valve 13 such as a reed valve is provided.

Further, although not shown, the turbocharger 11 may be configured such that the turbine and the compressor 25 are connected by a shaft, and an electric / generator is provided on the shaft to function as an energy recovery device. For example, when the engine is running at a low speed, the exhaust gas energy sent to the turbine can be converted into electric energy and recovered by the energy recovery device.

As described above, the two-cycle adiabatic engine according to the present invention includes a supercharging system that draws intake air from the turbocharger 11 into the combustion chamber 8 through the second intake passage 12 and the intake port 18, and a crank through the communication hole 19 with the outside air. And a supercharging system having a supercharging system that turbocharges outside air into the chamber 27 and sucks intake air from the crank chamber 27 into the combustion chamber 8 through the first intake passage 17 and the intake port 18. Since the three check valves 13, 14, and 15 are provided, the following functions can be achieved.

That is, when the engine is rotating at low speed, the amount of exhaust gas of the engine is small, and the exhaust gas energy of the exhaust gas sent to the turbine of the turbocharger 11 is small. Therefore, the amount of air sent from the air outlet 26 of the compressor 25 in the turbocharger 11 is small, the intake pressure is low, and the air flow is almost stopped, so the third check valve 13 is closed. State.
In that state, the first check valve is moved by the rising stroke of the piston 7.
15 is opened, air is sucked from the outside air into the crank chamber 27 from the outside air, the first check valve 15 is closed and the second check valve 14 is opened in the descending stroke of the piston 7, and the air in the crank chamber 27 is released. It is pushed into the intake port 18 through the first intake passage 17 and then from the intake port 20 into the combustion chamber 8. Therefore, a sufficient amount of intake air at the time of low speed of the engine can be secured.

In addition, the engine speed is high and the turbocharger
The pressure of the air sent from the air outlet 26 of the compressor 25 in the compressor 11, that is, the boost pressure increases, and the air flows through the third check valve 13 opened from the second intake passage 12 to the intake port 18.
And, it is pushed into the combustion chamber 8 from the intake port 20. Therefore,
At the time of high speed of the engine, the intake air amount from the crank chamber 27 alone is insufficient, so that the intake function of the turbocharger 11 ensures a sufficient intake air amount. Therefore, a desired intake air amount can be ensured in the entire operation region of the engine.

〔The invention's effect〕

The two-cycle adiabatic engine according to the present invention is configured as described above, and has the following effects.

That is, the two-cycle heat-insulated engine has a first portion that connects the lower surface of the cylinder head and the upper portion of the cylinder liner, the exhaust valve disposed in the cylinder head, the intake port formed in the lower portion of the cylinder liner, and the outside air to the crank chamber.
A check valve, a second check valve provided in a first intake passage connecting the crank chamber to the intake port, and an air outlet of a compressor of the turbocharger provided in a second intake passage communicating with the intake port. Since the engine is composed of the third check valve, when the engine speed is low, the exhaust gas amount of the engine is small,
Since the intake pressure sent out from the compressor of the turbocharger is low and the air flow is almost stopped, the first non-return flight is opened by the ascending stroke of the piston to suck air from outside air into the crank chamber, and In the descending stroke, the first check valve is closed and the second check valve is opened, and air in the crank chamber is sucked into the combustion chamber through the first intake passage. When the engine rotation speed becomes high and the boost pressure of the turbocharger rises, the third check valve opens and intake air is sucked from the second intake passage into the combustion chamber.

As described above, if the turbocharger is provided for the engine, the supercharging path of the compound supercharging system is automatically switched in accordance with the operation state in the entire operation range of the engine, and the intake air is sufficiently supplied to the combustion chamber. This makes it possible to provide an ideal engine that can supply the air at a low speed of the engine and can secure a sufficient amount of the intake air at a high speed in accordance with the operation state thereof.

Moreover, compared to the supercharger, the turbocharger has extremely good torque characteristics in the high-speed rotation region. As described above, if the intake air is actively sent to the combustion chamber in the high-speed region of the engine, an extremely good combustion state is obtained. If the adiabatic engine is operated for two cycles, the cylinder head is in a high temperature region, but the lower part of the cylinder is in a low temperature region, so that the intake air, that is, fresh air, is not affected by the heat in the high temperature region. Also, it is possible to prevent the intake air flow rate from decreasing due to thermal expansion.

Further, the exhaust valve is configured as a uni-flow type arranged in the cylinder head to perform a scavenging action by an airflow in a fixed direction with respect to the cylinder center line, efficiently exhaust the exhaust gas from the exhaust port, and then exhaust the exhaust gas. Since the intake air is blown in a state where the area of the negative pressure is filled in the wake of the pulse wave, the flow is unidirectional. Therefore, even if the upper wall temperature of the combustion chamber is high, the decrease in the suction efficiency is small,
The efficiency of the engine can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining one embodiment of a two-cycle adiabatic engine according to the present invention. 1 ... Exhaust valve, 3 ... Cylinder head, 4 ... Cylinder liner, 5 ... Bottom part of cylinder head, 6 ... Cylinder block, 7 ... Piston, 8 ... Combustion chamber, 9 ...
Cylinder liner upper part, 10 ... heat insulating gasket, 11 ... turbocharger, 12 ... second intake passage, 13 ... third check valve, 14 ... second check valve, 15 ... first check valve , 17 ... 1st
Intake passage, 20 ... Inlet, 25 ... Compressor, 26 ...
Air outlet, 27 ... Crank chamber.

Claims (1)

(57) [Claims] A first check valve for communicating the outside air to a crank chamber; an exhaust valve disposed in a lower portion of the cylinder head and an upper portion of the cylinder liner, an upper portion of the cylinder head, an intake port formed in a lower portion of the cylinder liner, and an outside air. A second check valve provided in a first intake passage communicating the crank chamber with the intake port;
A two-cycle adiabatic engine comprising a third check valve provided in a second intake passage communicating an air outlet of a compressor of a turbocharger with the intake port.