JPH05214947A - Two-stroke engine with turbo-charger - Google Patents

Abstract

PURPOSE:To provide a two-stroke engine having a turbo-charger effectively recovering exhaust energy. CONSTITUTION:An exhaust passage 11 arranged with an exhaust valve 9 is formed on a cylinder head 1, an exhaust port 4 opened near the bottom dead point of a piston is formed at the lower section of a cylinder 10, a turbo-charger 5 is communicated to the exhaust port 4 via an exhaust pipe 8, an opening/ closing valve 3 is provided on the exhaust port 4, the exhaust port is opened when the cylinder pressure is a preset value or above in the exhaust stroke, and it is closed when the cylinder pressure is the preset value or below. The high-pressure exhaust energy at the initial stage of the exhaust stroke in the turbo-charger can be effectively recovered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke engine having a turbocharger driven by the exhaust energy of the engine.

[0002]

2. Description of the Related Art Generally, regarding the operation of an engine, the operations of an explosion stroke (that is, an expansion stroke), an exhaust stroke, an intake stroke and a compression stroke are sequentially repeated. There are two methods. In a two-stroke engine, an exhaust port is formed in the cylinder head or the lower part of the cylinder, a scavenging port is provided in the lower part of the cylinder, and one stroke is completed by two stalks of the piston. be able to. Conventionally, an engine that has a turbocharger and an energy recovery turbine driven by exhaust energy is connected to the exhaust port such as an exhaust manifold connected to the exhaust port downstream of the turbocharger and energy recovery turbine, and the exhaust energy generated by the engine Is recovered by a turbocharger, an energy recovery turbine or the like, and drives a compressor, or is recovered by a battery or the like as electric energy by a generator / motor.

Further, as an exhaust energy recovery system for an engine, there is one disclosed in Japanese Patent Application Laid-Open No. 59-20526. The exhaust energy recovery system of the engine is
It suppresses the dissipation of heat generated inside and recovers the energy of the exhaust gas.The rotary shafts of the DC generator are directly connected to the turbine shafts of the multiple exhaust turbines that are sequentially installed at the tip of the engine exhaust manifold. In addition, the rotating shaft of the DC motor is connected to the rotating shaft of the engine, the electric energy generated from the DC generator is applied to the DC motor to drive it, and the output of the DC motor is fed back to the output shaft of the engine. Is.

Further, Japanese Patent Laid-Open No. 3-50363 discloses that
A two-stroke adiabatic engine is disclosed. In the two-stroke heat insulation engine, the lower surface of the head and the upper portion of the liner are constructed in a heat insulating structure, an exhaust valve is arranged in an exhaust port formed in the lower surface of the head, and a heat insulating gasket is arranged at the boundary between the upper portion of the liner and the lower portion of the liner. However, many intake ports are formed in the lower part of the liner, and the intake ports are opened to intake ports formed in the outer periphery of the lower part of the liner.

[0005]

By the way, in a two-stroke engine, when a turbocharger is provided, it is impossible from the two-stroke principle to make the exhaust pressure higher than the scavenging pressure. However, the in-cylinder pressure immediately before the exhaust stroke is several kg / cm ² or more, and if the high in-cylinder pressure is utilized, it is possible to effectively recover the exhaust energy by the exhaust turbine. However, in reality, the pressure once expands to the pressure before the exhaust turbine, and the pressure expands to the atmospheric pressure. Only the pressure difference can be recovered by the exhaust turbine. In addition, in the case of considering increasing the pressure before the exhaust turbine and increasing the amount of recovery thereof, in the two-stroke engine, the scavenging air pressure needs to be raised to a pressure higher than the pressure before the exhaust turbine, and the energy required for this increases. However, the total recovery efficiency does not improve.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems, and in a two-stroke engine in which a first exhaust port having an exhaust valve arranged in a cylinder head is formed and a scavenging port is formed in a lower portion of the cylinder, A second exhaust port in which an opening / closing valve is arranged is formed in the lower part of the cylinder, the second exhaust port is communicated with a turbocharger, and high-speed and high-pressure exhaust gas in the early stage of the exhaust stroke is sent to the turbocharger to increase the exhaust pressure. Exhaust energy is effectively recovered to increase the recovered energy, the amount of exhaust gas in the cylinder is reduced in the initial stage of the exhaust stroke, and the piston compression work in the exhaust stroke by the first exhaust port is reduced and remains in the cylinder. Has a turbocharger that reduces residual gas to improve intake efficiency and prevents engine output from decreasing
It is to provide a stroke engine.

[0007]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention, in a two-stroke engine having a turbocharger driven by the exhaust energy of the engine, is formed in a cylinder head and a first exhaust port in which an exhaust valve is arranged, and is formed in the lower part of the cylinder opening near the piston bottom dead center. A second exhaust port, a scavenging port formed in a lower portion of the cylinder below the second exhaust port, a turbocharger communicating with the second exhaust port through an exhaust pipe, and a cylinder pressure in the exhaust stroke of the second exhaust port. The present invention relates to a two-stroke engine having a turbocharger having an opening / closing valve that opens above a predetermined level and closes below a predetermined level.

[0008]

The two-stroke engine having the turbocharger according to the present invention is constructed as described above and operates as follows. That is, 2 with this turbocharger
A stroke engine has a cylinder head having a first exhaust port in which an exhaust valve is arranged, a second exhaust port opening near a piston bottom dead center formed at a lower portion of the cylinder, and a lower cylinder portion located below the second exhaust port. A scavenging port is formed, a turbocharger is connected to the second exhaust port through an exhaust pipe, and an opening / closing valve is provided to open the second exhaust port at a pressure equal to or higher than a predetermined pressure and close it at a predetermined pressure or lower during an exhaust stroke. Therefore, high-pressure exhaust energy in the early stage of the exhaust stroke can be sent to the turbocharger through the second exhaust port, and the exhaust energy can be effectively recovered by the turbocharger.

That is, in this two-stroke engine, in the early stage of the exhaust stroke, the exhaust gas in the cylinder can be exhausted from the second exhaust port through the opening / closing valve to the turbine upstream side of the turbocharger, and the exhaust pressure is large even if the exhaust pressure is large. Most of the high-pressure gas in the blowdown of the engine flows out from the second exhaust port in a short time, so that the turbine can be driven, the compressor can be driven, and when the turbocharger is provided with a power generator / motor, the power generation can be performed. -It can be recovered as electric energy by an electric motor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a two-stroke engine having a turbocharger according to the present invention will be described below with reference to the drawings. 1 is a schematic sectional view showing an embodiment of an engine having a turbocharger and a recovery turbine according to the present invention and showing a closed state of an opening / closing valve, and FIG. 2 is a schematic sectional view showing an opening state of the opening / closing valve of FIG. 3 is a schematic explanatory view showing an example of a turbocharger having a generator / motor incorporated in the two-stroke engine of FIG. 1, and FIG.
FIG. 3 is a schematic explanatory view showing an example of an energy recovery device incorporated in the 2-stroke engine of FIG.

As shown in the figure, the two-stroke engine having the turbocharger has a turbocharger 5 and an energy recovery device 6 driven by the exhaust energy of the engine. This two-stroke engine includes a cylinder block 2, a cylinder head 1 fixed to the cylinder block 2, a cylinder 10 formed in the cylinder block 2, a piston 7 that reciprocates in the cylinder 10, that is, a cylinder, and a reciprocation of the piston 7. It has a connecting rod and a crankshaft that convert motion into rotary motion. In FIG. 1, the cylinder 10 formed in the cylinder block 2 is schematically illustrated. The cylinder head 1 is provided with an exhaust port 11 which is a first exhaust port, and a fuel injection nozzle 32 for injecting fuel into the cylinder. An exhaust valve 9 is arranged in the exhaust port 11. Further, a scavenging port 12 is formed in the lower portion of the cylinder 10. The exhaust port 11 formed in the cylinder head 1 is connected to the exhaust manifold 13 via a manifold gasket. The exhaust manifold 13 is provided in the exhaust passage 1 on the downstream side of the turbocharger 5.
7, or the exhaust passage 1 on the downstream side of the energy recovery device 6
Connected to eight.

In the two-stroke engine having the turbocharger, the exhaust port 4 which is the second exhaust port opening at the lower part of the cylinder 10 and near the piston bottom dead center is formed, and the exhaust port 4 is exhausted. Tube 8
It is characterized by being connected to the turbine scroll 14 of the turbine 20 in the turbocharger 5 through. Further, the opening position of the exhaust port 4 in the cylinder is above the opening position of the scavenging port 12 in the cylinder. In other words, the scavenging port 12 is formed below the exhaust port 4 and below the cylinder. Furthermore, in the exhaust port 4,
A rotary valve 3, which is an opening / closing valve that opens and closes when the cylinder pressure is equal to or higher than a predetermined value in the exhaust stroke, is arranged.

The rotary valve 3 is shown in a state in which the exhaust port 4 is closed in FIG. 1, and in a state in which the exhaust port 4 is open in FIG. The rotary valve 3 can be configured to operate at the same rotation speed in synchronization with engine rotation. Alternatively, the controller may be configured to control in response to engine operating conditions. Also, the compressor 1 of the turbocharger 5
The air pressurized in 9 is sent to the intake manifold 16 through the intake passage 24, for example, through an intercooler or the like.

Further, as shown in FIG. 3, the turbocharger 5 incorporated in this two-stroke engine has a turbine 20, a compressor 19 connected to a shaft 23 fixed to the turbine 20, and a power generation / provided on the shaft 23. It has an electric motor 21. The turbine scroll 14 on the inlet side of the turbine 20 communicates with the exhaust pipe 8.
The exhaust passage 17 on the outlet side of the turbine 20 communicates with the turbine scroll 26 on the inlet side of the power generation turbine 25 of the energy recovery device 6 shown in FIG. The exhaust passage 18 on the outlet side of the power generation turbine 25 is open to the atmosphere through, for example, an exhaust gas purifying device. The energy recovery device 6 is configured such that a power generator 27 is provided on the shaft 22 fixed to the power generation turbine 25, and exhaust energy is recovered by the power generator 27.

The operation of the two-stroke engine constructed as described above will be described with reference to FIG. FIG. 5 is a diagram illustrating an embodiment of the operation of a two-stroke engine having this turbocharger. In FIG. 5, the displacement of the piston 7 when the piston 7 reciprocates in the cylinder 10 is indicated by the symbol P, the top dead center is indicated by TDC, and the bottom dead center is indicated by BDC. Further, in FIG. 5, the opening period of the on-off valve 3 in this two-stroke engine is indicated by the symbol A,
The open period of the scavenging port 12 is indicated by reference symbol B, the open period of the exhaust valve 9 is indicated by reference symbol C, and the open period of the exhaust port 4 is indicated by reference symbol D. Therefore, by closing the open / close valve 3, the exhaust port 4 is closed, and the open period is shortened.
In FIG. 5, reference numeral E indicates a closed period in which the exhaust port 4 is closed by closing the open / close valve 3.

In this two-stroke engine, when the piston 7 becomes close to the top dead center TDC in the compression stroke and the cylinder air is compressed and becomes high temperature and high pressure, the fuel injection nozzle 32
Fuel is injected into the cylinder from it, and it mixes with the compressed air and burns. In the combustion stroke, the piston 7 descends. When the piston top surface 15 of the piston 7 starts to wrap with the upper portion of the exhaust port 4, that is, when the exhaust port 4 begins to open in the cylinder, the opening / closing valve 3 is opened to the position shown in FIG. The high-temperature and high-pressure combustion gas is exhausted to the exhaust pipe 8 through the exhaust port 4 and the opening / closing valve 3 and then sent to the turbine 20 of the turbocharger 5. In this case, the pressure in the exhaust pipe 8 has a high exhaust pressure because the turbocharger 5 and the energy recovery device 6 are provided, but the in-cylinder pressure becomes higher than the exhaust pressure. Therefore, most of the combustion gas in the cylinder flows out in a short time.

The piston 7 is further lowered, and the piston top surface 1
Since the opening / closing valve 3 is rotating at the timing when 5 starts to wrap with the upper portion of the scavenging port 12, that is, the timing when the scavenging port 12 starts to open in the cylinder, the opening / closing valve 3 reaches the position shown in FIG. Close port 4. The exhaust valve 9 opens at the closing timing of the open / close valve 3,
The exhaust port 11 is in communication with the inside of the cylinder. here,
Closing the exhaust port 4 by the open / close valve 3 and the exhaust valve 9
Although the timing with which the exhaust port 11 is opened is almost the same, there is no problem even if there is some overlap.

Next, the combustion gas in the cylinder is exhausted from the exhaust port 11.
And the fresh air is introduced into the cylinder through the scavenging port 12, and the residual gas in the cylinder is exhausted from the exhaust port 11 by the fresh air. The exhaust gas discharged from the exhaust port 11 passes through the exhaust manifold 13 and is discharged to the exhaust passage 17 on the downstream side of the turbocharger 5 or the exhaust passage 18 on the downstream side of the energy recovery device 6.

In a two-stroke engine having this turbocharger, the exhaust port 4 is closed by the operation of the opening / closing valve 3, the scavenging port 12 is opened and the exhaust port 11 is opened by the operation of the exhaust valve 9. As can be seen, the pressure in the exhaust port 4 is the highest, the pressure in the scavenging port 12 continues, and the pressure in the exhaust port 11 is low. Therefore, the opening / closing valve 3 is attached to the exhaust port 4.
If the exhaust gas is not provided, the phenomenon that the exhaust gas flows back into the cylinder due to the pressure in the exhaust pipe 8, but at this time, since the exhaust port 4 is closed by the opening / closing valve 3, the exhaust gas enters the cylinder. The backflow phenomenon does not occur. Also, the exhaust port 11
The pressure inside is lower than the pressure inside the scavenging port 12,
Good scavenging process. Subsequently, the piston 7 rises again, the scavenging / intake stroke by the exhaust valve 9 and the scavenging port 12 is completed, and the piston shifts to the compression stroke. This scavenging
The on-off valve 3 is in the closed state during the intake stroke and the compression stroke.

Therefore, in the two-stroke engine having this turbocharger, the opening / closing valve 3 opens near the piston bottom dead center and the exhaust port 4 communicates with the inside of the exhaust pipe 8. The combustion gas is exhausted to the upstream side of the turbine 20 of the turbocharger 5, and the exhaust gas is sent to the power generation turbine 25 of the energy recovery device 6 from the outlet side of the turbine 20, that is, the exhaust passage 17, after driving the turbine 20. The exhaust gas is exhausted to the outside after driving the power generation turbine 25. Therefore, the effective exhaust area for exhausting the exhaust gas is increased by the amount corresponding to the exhaust port 4, and the exhaust gas in the cylinder is exhausted to the upstream side of the turbine 20 of the turbocharger 5 through the exhaust port 4, and the exhaust port is exhausted even if the exhaust pressure is large. Since high-pressure gas from the blowdown of the engine flows out from 4 in a short time, the turbine 20 of the turbocharger 5 can be driven, the compressor 19 can be driven, and the power generation / motor 21 provided in the turbocharger 5 can recover it as electric energy. can do.

Furthermore, if the exhaust manifold 13 is connected to the upstream side of the energy recovery device 6, the energy recovery device 6 recovers the exhaust energy of the remaining exhaust gas exhausted from the exhaust port 11.

Next, another embodiment of a two-stroke engine having a turbocharger according to the present invention will be described with reference to FIGS. 6 and 7. Compared with the above-mentioned embodiment, this embodiment has exactly the same structure and function except that the structure of the on-off valve is different. Therefore, the same parts are designated by the same reference numerals and duplicated. The description is omitted. In the two-stroke engine having the turbocharger of this embodiment, the opening / closing valve 3 includes the valve case 28 attached to the cylinder block 2 and the bearing 3 in the valve case 28.
1 and a tubular rotary valve 30 rotatably attached to the rotary valve 30. The cylinder block 2 is
Although the integrated structure is shown in FIG. 6, as shown in FIG. 7, the cylinder block 2 is connected to the main body portion 2B and the liner portion 2.
It can also be composed of L and L. Cylindrical rotary valve 3
0 is provided with an opening 29 which is aligned with the exhaust port 4 and communicates the exhaust gas with the exhaust pipe 8. The on-off valve 3 thus formed can satisfactorily control the exhaust gas from the exhaust port 4 to the exhaust pipe 8 and smoothly exhaust the exhaust gas.

[0023]

The two-stroke engine having the turbocharger according to the present invention is constructed as described above and has the following effects. That is, the two-stroke engine having this turbocharger has the second exhaust port formed in the lower part of the cylinder that opens near the piston bottom dead center.
Since the turbocharger is connected to the second exhaust port through an exhaust pipe and an opening / closing valve that opens at the beginning of the exhaust stroke at which the cylinder pressure is equal to or higher than a predetermined value and closes at other times is provided in the second exhaust port, the exhaust stroke High-pressure exhaust gas in the initial stage can be sent to the turbocharger through the on-off valve, and the exhaust energy can be effectively recovered by the turbocharger. That is, in the early stage of the exhaust stroke, the exhaust gas in the cylinder can be exhausted to the turbine upstream side of the turbocharger through the opening / closing valve opened from the second exhaust port, and even if the exhaust pressure is large, the engine can be exhausted from the second exhaust port. Since the blowdown high-pressure gas flows out in a short time, the turbine can be driven, the compressor can be driven, and when the turbocharger is provided with a generator / motor, it can be recovered as electric energy by the generator / motor.

Further, if an energy recovery device is provided downstream of the turbocharger, after driving the turbocharger, the exhaust gas is sent to the energy recovery device to drive the power generation turbine of the energy recovery device. Exhaust energy can be recovered.

Also, a considerable amount, for example, at the beginning of the exhaust stroke,
Since 70% of exhaust gas is exhausted from the second exhaust port, the amount of exhaust gas in the cylinder is reduced and the exhaust gas pressure is lowered, and the combustion gas pressure is already reduced in the compression stroke of the piston.
The compression work of the piston during the exhaust stroke, i.e. when the piston rises, is reduced.

Further, if the first exhaust port formed in the cylinder head is communicated with the downstream side of the turbocharger and the upstream side of the energy recovery device, the remainder exhausted from the first exhaust port by opening the exhaust valve. Exhaust gas is sent to the upstream side of the energy recovery device, and the remaining exhaust gas drives the power generation turbine of the energy recovery device to recover exhaust energy.

Further, the absolute amount of the exhaust gas in the cylinder decreases through the exhaust port and the exhaust hole at the end of the explosion stroke and the beginning of the exhaust stroke, and the exhaust gas pressure becomes low. Since the amount of exhaust gas in the cylinder is reduced, the compression work of the piston when the piston rises is reduced, especially the cylinder pressure at the end of the exhaust stroke is reduced,
Since the amount of residual exhaust gas is small, sufficient intake air is introduced into the cylinder in the subsequent scavenging and intake strokes, and intake efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a two-stroke engine having a turbocharger according to the present invention and showing a closed state of an on-off valve.

FIG. 2 is a schematic sectional view showing an open state of the on-off valve of FIG.

FIG. 3 is a schematic explanatory view showing an example of a turbocharger having a generator / motor incorporated in the two-stroke engine of FIG.

FIG. 4 is a schematic explanatory diagram showing an example of an energy recovery device incorporated in the two-stroke engine of FIG.

FIG. 5 is a diagram showing an example of the operation of a two-stroke engine having this turbocharger.

FIG. 6 is a schematic sectional view showing another embodiment of a two-stroke engine having a turbocharger according to the present invention and showing a closed state of an opening / closing valve.

7 is a schematic cross-sectional view taken along the line FF of FIG.

[Explanation of symbols]

 1 Cylinder Head 2 Cylinder Block 3 Open / Close Valve 4 Exhaust Port (Second Exhaust Port) 5 Turbocharger 6 Energy Recovery Device 7 Piston 8 Exhaust Pipe 9 Exhaust Valve 10 Cylinder 11 Exhaust Port (First Exhaust Port) 12 Scavenging Port 15 Piston Top Surface 17, 18 Exhaust passage

Claims (1)

[Claims] 1. In a two-stroke engine having a turbocharger driven by exhaust energy of the engine, a first exhaust port formed in a cylinder head and having an exhaust valve, and a lower part of the cylinder opened near a piston bottom dead center. Second exhaust port, a scavenging port formed in the lower portion of the cylinder below the second exhaust port,
A two-stroke engine having a turbocharger that communicates with the second exhaust port through an exhaust pipe, and a turbocharger that has an opening / closing valve that opens the second exhaust port at a predetermined cylinder pressure or higher and closes it at a predetermined pressure or lower during an exhaust stroke. ..