JPH06323158A - Turbocompound engine - Google Patents

Abstract

PURPOSE:To provide a turbocompound engine for improving collecting energy by reducing an exhaust pressure and work volume of the engine. CONSTITUTION:A turbocharger 5 is arranged in the first exhaust pipe 7 communicating with the first exhaust port, and further an energy collector 6 is arranged in the following exhaust pipe 8 in a back wash of the turbocharger 5. In the second exhaust pipe 9, the second exhaust port 14 communicates with the following exhaust pipe 8. In the first exhaust valve 13, the first exhaust port 12 is opened in the latter half of an expansion stroke and closed to the halfway of an exhaust stroke. In the second exhaust valve 15, the second exhaust port 14 is opened in the first half of an exhaust stroke and closed to the first half of an intake stroke. A bypass exhaust pipe 10 is constituted such that the first exhaust pipe 7 is connected to the second exhaust pipe 9 to enable an exhaust pressure to reduce of the first exhaust pipe 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo compound engine having a turbocharger driven by exhaust energy of an engine and an energy recovery device.

[0002]

2. Description of the Related Art Generally, in an engine equipped with a turbocharger, when controlling the supercharging pressure, a wastegate is provided in an exhaust passage bypassing the turbocharger communicating with the exhaust manifold. The maximum pressure is controlled only by opening and closing. The waste gate is a kind of relief valve and is provided in the exhaust gas passage that bypasses the turbine of the turbocharger.

Conventionally, as a turbo compound internal combustion engine, there is one disclosed in Japanese Utility Model Publication No. 62-40096. The turbo compound internal combustion engine is a turbocharged internal combustion engine in which a power turbine driven by exhaust pressure is installed in an engine exhaust passage downstream of an exhaust turbine of a turbocharger, and the output of the power turbine is added to an engine output shaft. There is provided an exhaust bypass passage that bypasses the exhaust turbine and the power turbine, and a passage opening / closing valve that opens the exhaust bypass passage at a low engine load and a high engine speed range is provided. The turbo compound internal combustion engine having the above-described configuration eliminates an increase in pumping loss at the time of low engine load, improves fuel efficiency, prevents excessive air supply by the turbocharger, and improves fuel efficiency in a high engine speed range. It is intended to improve.

Further, an engine equipped with a turbocharger disclosed in Japanese Patent Laid-Open No. 5-33664 has a bypass passage for bypassing the turbocharger in an exhaust passage communicating with an exhaust manifold, and adjusts the opening degree of the bypass passage. Provide a waste gate. Uei opening of waste gate in response to the detection signal of the operating state of the engine by the sensor by the controller, without reducing the engine output in accordance with the engine speed and engine load in accordance with boost map set in advance, the amount of the NO _X Can be controlled so as to obtain the optimum boost pressure.

[0005]

By the way, in the turbo compound engine, the exhaust gas energy is recovered by operating the turbocharger and the energy recovery device by the exhaust gas energy, but unless the pressure of the exhaust gas is raised, the turbocharger and the The turbine work of the energy recovery device cannot be increased. However, when the exhaust pressure in the exhaust pipe increases, it is necessary to work in the exhaust stroke of the engine, which reduces the amount of energy recovered by the turbine.

FIG. 5 is a graph showing the relationship between the exhaust pressure and the average effective pressure of the turbo compound engine. In FIG. 5, when the exhaust pressure in the exhaust pipe is plotted on the horizontal axis and the average effective pressure of the turbo compound engine is plotted on the vertical axis, for example, as shown by symbol A in FIG. 5, the exhaust pressure in the exhaust pipe increases. Then, the average effective pressure of the turbo compound engine decreases. Therefore, as indicated by the symbol B, when the exhaust pressure in the exhaust pipe exceeds a predetermined value, work is performed in the exhaust stroke of the engine, and the output of energy recovery by the turbine decreases.

Therefore, as described above, the object of the present invention is to send the exhaust gas to the turbocharger through the first exhaust port in the first half of the exhaust stroke where the combustion gas has a sufficient flow velocity, and drive the turbocharger with the exhaust gas energy. In the latter half of the exhaust stroke, where the flow velocity of the combustion gas has decreased, exhaust gas bypasses the turbocharger through the second exhaust port and is sent to the energy recovery device, and the back pressure at the turbine inlet of the energy recovery device is low. Therefore, it is an object of the present invention to provide a turbo compound engine in which the engine work in the exhaust stroke is reduced and the energy of the exhaust gas corresponding to the reduced back pressure is recovered to increase the engine output.

[0008]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention relates to a first exhaust port and a second exhaust port formed in a cylinder head that communicates with a combustion chamber of a heat shield structure, a turbocharger arranged in a first exhaust pipe that communicates with the first exhaust port, and the turbocharger. An energy recovery device disposed in the subsequent exhaust pipe downstream of the charger, a second exhaust pipe communicating the second exhaust port with the subsequent exhaust pipe, and opening the first exhaust port in the latter half of the expansion stroke and the exhaust stroke. The present invention relates to a turbo compound engine having a first exhaust valve that is closed by the middle and a second exhaust valve that opens the second exhaust port in the first half of the exhaust stroke and is closed by the first half of the intake stroke.

Further, in this turbo compound engine, the first exhaust valve opens the first exhaust port at 20 ° to 50 ° before the expansion stroke bottom dead center and from 90 ° to 120 ° after the exhaust stroke bottom dead center. And the second exhaust valve connects the second exhaust port to 50 ° to 9 ° after the bottom dead center of the exhaust stroke.
It opens at 0 ° and closes at 10 ° to 20 ° after the top dead center of the suction stroke.

Further, this turbo compound engine has a bypass exhaust pipe which connects the first exhaust pipe to the second exhaust pipe and in which a first control valve is arranged.

Further, in this turbo compound engine, a second control valve is arranged at a connecting portion between the second exhaust pipe and the subsequent exhaust pipe.

[0012]

The turbo compound engine according to the present invention is constructed as described above and operates as follows. That is, in this turbo compound engine, a turbocharger is provided in a first exhaust pipe communicating with the first exhaust port, an energy recovery device is provided in a subsequent exhaust pipe downstream of the turbocharger, and a second exhaust pipe is provided. Communicates the second exhaust port with the subsequent exhaust pipe, opens the first exhaust port in the latter half of the expansion stroke and closes it by the middle of the exhaust stroke by the first exhaust valve, and uses the second exhaust valve for the first exhaust port. Since the two exhaust ports are opened in the first half of the exhaust stroke and closed by the first half of the intake stroke, the exhaust gas is sent to the energy recovery device through the second exhaust pipe when the energy of the exhaust gas exhausted from the combustion chamber is reduced. And
Since the exhaust pressure is low in the subsequent exhaust pipe, the work of the engine in the exhaust stroke is reduced, and energy is recovered by the energy recovery device, so that the engine output and recovery efficiency are improved, and fuel efficiency is improved.

Further, in this turbo compound engine, the first exhaust pipe is connected to the second exhaust pipe and the first exhaust pipe is connected to the first exhaust pipe.
Since it has a bypass exhaust pipe in which a control valve is arranged,
The exhaust pressure in the first exhaust pipe is reduced to the exhaust pressure in the subsequent exhaust pipe, the residual amount of exhaust gas in the combustion chamber, that is, the cylinder is reduced, and the intake air charging efficiency is increased.

Further, in this turbo compound engine, since the second control valve is arranged at the connecting portion between the second exhaust pipe and the subsequent exhaust pipe, the second exhaust pipe is connected to the second exhaust pipe. Backflow of the exhaust gas of
It is possible to continue driving the engine accurately and smoothly.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a turbo compound engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing an embodiment of a turbo compound engine according to the present invention, FIG. 2 is an explanatory view showing valve timing of the turbo compound engine of FIG. 1, and FIG. 3 is a turbocharger incorporated in this turbo compound engine. And FIG. 4 are schematic explanatory views showing an energy recovery device incorporated in this turbo compound engine.

This turbo compound engine has a turbocharger 5 and an energy recovery device 6 which are driven by the exhaust energy of the engine. This turbo compound engine has a cylinder block 18,
A cylinder head 3 fixed to the cylinder block 18,
A cylinder liner 16 fitted in a hole formed in the cylinder block 18, a head liner 4 forming the main chamber 1 arranged in a hole formed in the cylinder head 3, and a cylinder liner 16 and a head liner 4. Cylinder 17,
A piston 11 that reciprocates in the cylinder 17, a sub-chamber member 38 that forms the sub-chamber 2 disposed in the hole 37 of the cylinder head 3, and a fuel injection nozzle 3 that sprays fuel into the sub-chamber 2.
Have four.

The cylinder head 3 is provided with at least a first exhaust port 12 and a second exhaust port 14 whose inner wall surface 44 is made of a heat insulating structure made of ceramics or the like. Although not shown, the intake port is a cylinder. It is formed on the head 3 or the lower part of the cylinder. The first exhaust port 12 has a first opening / closing portion that opens / closes by the operation of the first cam 35.
An exhaust valve 13 is provided. Also, the second exhaust port 1
A second exhaust valve 15 that opens and closes the second exhaust port 14 by the operation of the second cam 36 is disposed at 4. Although one first exhaust port 12 and one second exhaust port 14 are shown in FIG. 1, each of them may be composed of a plurality.

The main chamber 1 and the sub chamber 2 are communicated with each other through a plurality of communication holes 22 formed in the sub chamber member 38. Communication hole 22
Are formed so as to be inclined from the sub chamber 2 toward the periphery of the main chamber 1. The piston 11 is composed of a piston head 23 and a piston skirt 24 fixed to the piston head 23. The main chamber 1 and the sub chamber 2 are made of ceramics or the like in a heat shield structure. Headliner 4
Is composed of a head lower surface portion 32 made of ceramics and a liner upper portion 33 formed integrally with the head lower surface portion 32. When an intake port is formed in the cylinder head 3, an intake valve is arranged in the intake port.

In this turbo compound engine, the first exhaust port 12 formed in the cylinder head 3
Is communicated with a first exhaust pipe 7 which is a main exhaust pipe which is an exhaust passage through a manifold gasket and the like.
Is connected to the turbine scroll 39 of the turbine 25 of the turbocharger 5. As the turbocharger 5, for example, as shown in FIG. 3, a turbocharger including a generator / motor 26 can be used, and a turbine 25 into which exhaust gas of the engine is sent, a shaft 28 having the turbine 25 fixed at one end, and a shaft It has a compressor 27 attached to the other end of 28 and a generator / motor 26 attached on a shaft 28. An energy recovery device 6 is arranged in the exhaust passage on the outlet side of the turbocharger 5, that is, in the subsequent exhaust pipe 8. As shown in FIG. 4, the energy recovery device 6 has a turbine 29 driven by exhaust gas introduced through a turbine scroll connected to a subsequent exhaust pipe 8, and a shaft 3 fixed to the turbine 29.
A generator 30 is arranged on the upper part of the unit 1.

This turbo compound engine is particularly equipped with a first exhaust port 12, a second exhaust port 14, and a first exhaust port formed in a cylinder head 3 communicating with a combustion chamber having a heat shield structure, that is, a main chamber 1 and a sub chamber 2. The turbocharger 5 disposed in the first exhaust pipe 7 communicating with the fuel cell 12, the energy recovery device 6 disposed in the subsequent exhaust pipe 8 downstream of the turbocharger 5, and the second exhaust port 14 are connected to the subsequent exhaust pipe 8. In the first half of the exhaust stroke, the second exhaust pipe 9 and the first exhaust port 12 which communicate with each other are set to open in the latter half of the expansion stroke and to be closed by the middle of the exhaust stroke. It has a second exhaust valve 15 which is set to open and close by the first half of the intake stroke. Specifically, the first exhaust valve 13 is set so as to open the first exhaust port 12 at 20 ° to 50 ° before the expansion stroke bottom dead center and close it at 90 ° to 120 ° after the exhaust stroke bottom dead center. Has been done. The second exhaust valve 15 is set to open the second exhaust port 14 at 50 ° to 90 ° after the bottom dead center of the exhaust stroke and close it at 10 ° to 20 ° after the top dead center of the intake stroke. .

Further, the first exhaust pipe 7 is a bypass exhaust pipe 10.
Is connected to the second exhaust pipe 9, and the bypass exhaust pipe 10 is provided with a first control valve 19. A second control valve 20 is arranged at a connecting portion 40 between the second exhaust pipe 9 and the subsequent exhaust pipe 8. Further, a check valve 21 is arranged at a connecting portion 41 between the second exhaust pipe 9 and the bypass exhaust pipe 10. The first control valve 19 provided in the bypass exhaust pipe 10 is opened / closed by an actuator 42, and the second control valve 20 provided in the second exhaust pipe 9 is opened / closed by an actuator 43. The actuators 42 and 43 are, for example, the first exhaust pipe 7 and the second exhaust pipe 9
And in response to the gas pressure in the subsequent exhaust pipe 8, that is, the exhaust pressure, depending on the case, in response to the set operating timing or the operating state of the engine such as the engine load or the engine speed, the controller is operated by a command from the controller. Bypass exhaust pipe 10
The first control valve 19 and the second exhaust pipe 9 are configured so that the second control valve 20 is opened and closed. Main room 1 and sub room 2
Regarding the heat shield structure of No. 3, the surface exposed to the combustion gas is made of ceramics having high heat resistance such as silicon nitride, and although not shown, aluminum titanate, potassium titanate, A heat shield structure is formed by interposing ceramics such as alumina fibers.

An embodiment of the operation of this turbo compound engine will be described with reference to the valve timing shown in FIG. This turbo compound engine has four intake strokes, compression strokes, combustion strokes or expansion strokes, and exhaust strokes.
It is operated in one cycle, and in the intake stroke, a normal operation stroke, for example, as shown by reference numeral I in FIG. 2, the intake valve opens the intake port and intake air is introduced into the main chamber 1. Next, as the piston 11 rises, the compression stroke is performed in the same manner as a normal operation stroke. For example, fuel is injected from the fuel injection nozzle 34 into the sub chamber 2 near the end of the compression stroke.
In the sub-chamber 2, the fuel is mixed with air and ignited and burned to enter the expansion stroke, and the engine rotates the work or crankshaft and then shifts to the exhaust stroke. At this time, the first control valve 1
9 is closed by the operation of the actuator 42, and the second control valve 20 is closed by the operation of the actuator 43.

Therefore, in the expansion stroke, the first exhaust valve 13 is actuated by the first cam 35 to open the first exhaust port 12 in the latter half of the expansion stroke, as indicated by reference numeral E ₁ in FIG.
In the middle of the subsequent exhaust stroke, the first exhaust valve 13 is returned by the return spring to operate so as to close the first exhaust port 12. Specifically, the first exhaust valve 13 opens the first exhaust port 12 at 20 ° to 50 ° before the expansion stroke bottom dead center and closes it at 90 ° to 120 ° after the exhaust stroke bottom dead center. As a result, the exhaust gas from the main chamber 1 passes through the first exhaust port 12 and the first exhaust pipe 7, and then the turbocharger 5
The turbine 25 of the turbocharger 5 is driven to operate the compressor 27, and the generator / motor 26 is driven to recover the exhaust gas energy. The power generation mode of the power generator / motor 26 is particularly effective when the engine is operating at high speed and high load. Then, the exhaust gas from the turbocharger 5 is passed through the subsequent exhaust pipe 8 to the energy recovery device 6
Is sent to drive the energy recovery device 6 and energy is recovered by the generator 30.

Next, the second exhaust valve 15 has a reference numeral E in FIG.
_As shown in ₂ , by the second cam 36, the first half of the exhaust stroke,
Specifically, the second exhaust port 14 is opened at 50 ° to 90 ° after the bottom dead center of the exhaust stroke, and the actuator 42,
43 operates to open the first control valve 19 and the second control valve 20 to send the exhaust gas remaining in the main chamber 1 to the subsequent exhaust pipe 8 through the second exhaust port 14, and
Subsequent exhaust pipe 8 through exhaust pipe 7 and bypass exhaust pipe 10
Send to. Therefore, the exhaust pressure in the first exhaust port 7 becomes as low as the exhaust pressure of the subsequent exhaust pipe 8, and the exhaust gas operates the energy recovery device 6 to recover energy. Next, the first exhaust valve 13 is closed, but the exhaust gas remaining in the main chamber 1 is sent to the subsequent exhaust pipe 8 through the second exhaust port 14, and the exhaust gas operates the energy recovery device 6 to generate energy. Is recovered. At this time, the second
Since the check valve 21 is arranged at the connecting portion 41 between the exhaust pipe 9 and the bypass exhaust pipe 10, the reverse flow of the exhaust gas from the second exhaust pipe 9 to the bypass exhaust pipe 10 does not occur. Then, the second exhaust valve 15 is returned by the return spring in the first half of the intake stroke, specifically, 10 ° to 20 ° after the top dead center of the intake stroke, and the second exhaust valve 15 closes the second exhaust port 14. . When the energy recovery operation of the turbocharger 5 and the energy recovery device 6 is completed, the actuators 42 and 43 are operated and the first control valve 19 closes the bypass exhaust pipe 10, and the second control valve 20 is set to the second control valve 20.
The exhaust pipe 9 is closed.

This turbo compound engine is driven by repeating the above operation cycle. Therefore, in the exhaust stroke, the exhaust pressure of the first exhaust pipe 7 is reduced by exhausting the exhaust gas to the subsequent exhaust pipe 8 through the bypass exhaust pipe 10, and the work of the engine in the exhaust stroke is indicated by the symbol C in FIG. As a result, the energy recovery efficiency is increased as shown by the symbol D in FIG. 5, and the engine performance is improved and the fuel consumption is improved by about 10% as compared with the conventional one. You can That is, in the conventional turbo compound engine, the exhaust gas in the main chamber was not discharged below the exhaust pressure in the exhaust pipe on the upstream side of the turbocharger, but in the turbo compound engine according to the present invention, The exhaust gas is exhausted to the exhaust pressure of the subsequent exhaust pipe 8, the residual amount of the exhaust gas in the main chamber 1 or the cylinder 17 is reduced, the intake air filling efficiency is improved, combustion is improved, smoke and soot are generated. It is possible to suppress the generation of particulates such as HC and HC.

[0026]

The turbo compound engine according to the present invention is constructed as described above and has the following effects. That is, this turbo compound engine
A turbocharger is provided in the first exhaust pipe communicating with the first exhaust port, an energy recovery device is provided in the subsequent exhaust pipe downstream of the turbocharger, and the second exhaust port is provided with the second exhaust port by the second exhaust pipe. A first exhaust valve opens the first exhaust port in the latter half of the expansion stroke and closes it by the middle of the exhaust stroke, and a second exhaust valve connects the second exhaust port in the first half of the exhaust stroke. It can be operated to open and close by the first half of the intake stroke, and when the exhaust gas is vigorously ejected from the main chamber to the first exhaust pipe, the turbocharger is effectively driven to recover energy, and then the main When the energy of the exhaust gas exhausted from the chamber is reduced, the exhaust gas bypasses the turbocharger and is sent to the energy recovery device through the second exhaust pipe to recover the energy. Do. Since the exhaust pressure in the subsequent exhaust pipe is low, the residual amount of exhaust gas in the main chamber is reduced accordingly, the work of the engine in the exhaust stroke is reduced, the engine output and the recovery efficiency are improved, and the fuel consumption is improved. Is improved. Moreover, the exhaust gas energy is sufficiently recovered by the energy recovery device.

Further, in this turbo compound engine, the first exhaust pipe is connected to the second exhaust pipe and the first exhaust pipe is connected to the first exhaust pipe.
Since it has a bypass exhaust pipe in which a control valve is arranged,
The exhaust pressure in the first exhaust pipe is reduced to the exhaust pressure in the subsequent exhaust pipe, the residual amount of exhaust gas in the combustion chamber, that is, the cylinder is reduced, and the intake air filling efficiency in the intake stroke can be increased. .

Further, in this turbo compound engine, since the second control valve is arranged at the connecting portion between the second exhaust pipe and the subsequent exhaust pipe, the secondary exhaust pipe is connected to the second exhaust pipe. Backflow of the exhaust gas of
It is possible to continue driving the engine accurately and smoothly.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of a turbo compound engine according to the present invention.

2 is an explanatory diagram showing valve timings of a first exhaust valve, a second exhaust valve, and an intake valve of the turbo compound engine of FIG. 1. FIG.

FIG. 3 is a schematic explanatory view showing a turbocharger incorporated in this turbo compound engine.

FIG. 4 is a schematic explanatory view showing an energy recovery device incorporated in this turbo compound engine.

FIG. 5 is a graph showing the relationship between the exhaust pressure in the exhaust pipe and the average effective pressure of the turbo compound engine.

[Explanation of symbols]

 1 Main Chamber 2 Sub Chamber 3 Cylinder Head 4 Headliner 5 Turbocharger 6 Energy Recovery Device 7 First Exhaust Pipe 8 Subsequent Exhaust Pipe 9 Second Exhaust Pipe 10 Bypass Pipe 11 Piston 12 First Exhaust Port 13 First Exhaust Valve 14 Fourth 2 Exhaust port 15 Second exhaust valve 17 Cylinder 19 First control valve 20 Second control valve

Claims (4)

[Claims] 1. A first exhaust port and a second exhaust port formed in a cylinder head communicating with a combustion chamber of a heat shield structure, a turbocharger disposed in a first exhaust pipe communicating with the first exhaust port, An energy recovery device disposed in the subsequent exhaust pipe downstream of the turbocharger, a second exhaust pipe that communicates the second exhaust port with the subsequent exhaust pipe, and the first exhaust port is opened and exhausted in the latter half of the expansion stroke. A turbo compound engine comprising: a first exhaust valve that is closed by the middle of the stroke; and a second exhaust valve that opens the second exhaust port in the first half of the exhaust stroke and is closed by the first half of the intake stroke. 2. The first exhaust valve opens the first exhaust port at 20 ° to 50 ° before an expansion stroke bottom dead center and closes 90 ° to 120 ° after an exhaust stroke bottom dead center, and The second exhaust valve connects the second exhaust port to the exhaust stroke after the bottom dead center of the exhaust stroke.
Open at 90 ° to 90 ° and 10 ° to 20 after top dead center of the suction stroke
The turbo compound engine according to claim 1, wherein the turbo compound engine is closed up to °. 3. The turbo compound engine according to claim 1, further comprising a bypass exhaust pipe that connects the first exhaust pipe to the second exhaust pipe and has a first control valve. 4. The turbo compound engine according to claim 1, wherein a second control valve is disposed at a connecting portion between the second exhaust pipe and the subsequent exhaust pipe.