JPH0373731B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a turbo compound engine,
In particular, the present invention relates to a turbo compound engine that can improve the recovery efficiency of exhaust gas energy over the entire speed range and improve the cylinder gas exchange rate to obtain stable output.

[Prior art] The combustion chamber of an insulated engine is made of ceramic,
A turbo compound engine is generally known as an engine that connects a turbocharger and a turbine to an exhaust manifold to efficiently recover exhaust gas energy.

This turbo compound engine attempts to recover exhaust gas energy through the diesel engine cycle and Brighton cycle, which insulates the engine as much as possible during the heat generation period and uses the thermal energy transferred to the exhaust gas to drive the turbocharger and turbine. It is something.

A precedent example of such a turbo compound engine is the two-stage supercharged internal combustion engine
152142) is known.

As shown in Figure 8, this two-stage supercharged internal combustion engine
Two exhaust valves d are provided for each cylinder c of the engine E ₁ ,
A high-pressure exhaust valve _d1 , which is also opened during the exhaust stroke, is connected to a high-pressure exhaust manifold e, and an exhaust passage f connected to the high-pressure exhaust manifold e is connected to the second turbocharger through the turbine h of the first turbocharger g. It is connected to the turbine j of the charger i and to a low pressure exhaust manifold k that opens later, and the exhaust passage l connected to the low pressure exhaust manifold k is connected to the second turbocharger i. It is something that will be done.

[Problems to be Solved by the Invention] In the above two-stage supercharged internal combustion engine, the high-pressure stage turbocharger is operated by a high pressure pulsating component (dynamic pressure) from the high-pressure manifold, and the low-pressure stage turbocharger is operated by a high pressure pulsating component (dynamic pressure) from the high-pressure manifold. The cylinder is operated by the combined exhaust (static pressure) of the exhaust passage after passing through the high-pressure stage turbocharger and the exhaust passage leading to the low-pressure exhaust manifold, and one exhaust valve is provided for each cylinder. Compared to the case where two turbochargers are installed in series in the exhaust passage leading to the exhaust valve,
This aims to effectively utilize exhaust energy and reduce pumping loss in the low speed range of the engine.

However, a configuration in which a low-pressure exhaust manifold is connected between the low-pressure stage and high-pressure stage turbochargers, as in the above-mentioned two-stage supercharged internal combustion engine, is effective for operating the low-pressure stage turbochargers. However, when considering the resistance of the turbine, there was a natural limit to the gas exchange rate as exhaust gas remained in the cylinder. If this gas exchange rate is poor, the intake efficiency of intake air will also be poor, resulting in a decrease in output, which is a problem.

[Means for Solving the Problems] The present invention aims to solve the above problems.

The present invention connects a turbocharger and a turbine for exhaust gas energy recovery in series to the main exhaust passage of an engine, and includes a sub-exhaust passage in the main exhaust passage downstream of the turbine that opens later than the main exhaust passage. These are connected to form a turbo compound engine.

[Operation] When the main exhaust passage and the auxiliary exhaust passage are opened after this, the exhaust gas from the main exhaust passage and the auxiliary exhaust passage is sequentially supplied to the turbocharger and the turbine, operating them well, and exhaust gas. Recovers thermal energy from gas. When the auxiliary exhaust passage is opened after the main exhaust passage is opened, the exhaust gas from the cylinder will pass through the auxiliary exhaust passage to the outside without any obstruction because the pressure in this auxiliary exhaust passage is low compared to the internal cylinder pressure of the engine. is discharged. Therefore, the pumping loss of the engine is reduced, the exhaust gas exchange rate is improved, the intake efficiency is improved, and stable output can be obtained.

[First Embodiment] A first embodiment of the turbo compound engine of the present invention will be described below based on the accompanying drawings.

Figure 1 shows a schematic cross section of a turbo compound engine.

In the figure, 1 is the cylinder body, 2 is the cylinder liner, 3 is the piston, 4 is the cylinder head,
7 is the main exhaust valve.

The cylinder liner 2 is made of highly insulating ceramic, and inside the cylinder liner 2,
A piston 3 is housed so as to be able to reciprocate. A cylinder chamber 5 is defined by a cylinder head 4 seated on the cylinder body 1 and integrally joined, the cylinder liner 2 and the piston 3. A main exhaust passage 6 communicating with a cylinder chamber 5 is formed within the cylinder head 4, and the cylinder chamber 5 is opened and closed by a main exhaust valve 7 provided within the cylinder head 4 so as to be able to freely reciprocate. It is becoming more and more like this.
8a is a valve seat on which the valve face 7a of the main exhaust valve 7 is seated. Further, a sub-exhaust passage 9 is formed in the cylinder head 4 at a position parallel to the main exhaust passage 6 and communicates with the cylinder chamber 5. It is designed to be opened and closed by a freely provided sub-exhaust valve 10. 8b is a valve seat on which the valve face 10a of the sub-exhaust valve 10 is seated. Exhaust manifolds are connected to the main exhaust passage 6 and the sub-exhaust passage 9, respectively, to form an exhaust system.

As shown in FIGS. 1 and 2, the exhaust manifold 11 connected to the main exhaust passage 6 is connected to the turbine scroll introduction part 12a of the turbocharger 12 as one collecting pipe. Exhaust manifold 1 connected to the exhaust part 14
8 is connected to the turbine scroll introduction part 15a of the turbine 15 for exhaust gas energy recovery. The exhaust section 16 of the turbine 15 is connected to an exhaust manifold 17 with a muffler. Therefore, the turbocharger 12 and the turbine 15 are connected to the exhaust manifold 1 which becomes part of the main exhaust passage 6.
1, 18, and 17 in order in the downstream direction. Connected to this exhaust gas energy recovery turbine 15 is an energy recovery device 30 that is operated directly or indirectly thereby to recover exhaust gas energy as motive power or electric power and reuse the energy. As the energy recovery device 30, for example, an alternator that can be recovered as electric power is employed.

On the other hand, the sub-exhaust passage 9 is connected to the sub-exhaust manifold 19.
turbine 15 for exhaust gas energy recovery via
Exhaust manifold 17 downstream from the connection part of
It is connected to the.

FIG. 2 shows an overall view of the turbo compound engine of the first embodiment. In the figure, 25 is an intake passage and 26 is an intake manifold. The intake passage 25 is connected to a compressor 27 of the turbocharger 12 via an intake manifold 26.

FIG. 3 shows an example of the opening/closing timing of the main and auxiliary exhaust valves 7 and 10.

As shown in the figure, the main exhaust valve 7 is opened before bottom dead center (BDC) and closed at a position beyond top dead center (TDC), whereas the auxiliary exhaust valve 10 is Before the main exhaust valve 7 is closed (for example, near the top dead center of the piston), it is opened and closed.

The operation of the first embodiment of the turbo compound engine of the present invention will be explained below based on the accompanying drawings.

As shown in FIGS. 1 and 2, when the engine E is operated, the main exhaust valve 7 is opened during the exhaust stroke, and the exhaust gas in the cylinder chamber 5 is transferred from the main exhaust passage 6 to the exhaust manifold 11, It is discharged to the outside via 18 and 17. Next, the main exhaust valve 7
Since the sub-exhaust valve 10 is opened with a delay, the sub-exhaust passage 9 is opened and the residual exhaust gas in the cylinder chamber 5 is discharged from the sub-exhaust passage 9. That is, by opening the main and auxiliary exhaust valves 7 and 10, the entire amount of exhaust gas in the cylinder chamber 5 is discharged to the outside. This prevents the cylinder chamber 5 from becoming high in temperature, and prevents the fresh air (intake air) introduced into the cylinder chamber 5 from being heated. Therefore, it is possible to stabilize suction efficiency and suppress a decrease in output.

Furthermore, since no exhaust gas remains in the cylinder chamber 5, the air supercharged by the turbocharger 12 is smoothly introduced into the cylinder chamber 5 from the beginning of intake, resulting in improved intake efficiency. can be improved. This reduces the load on the turbocharger 12 and can substantially increase the workload of the turbine 15. Therefore, as in the past, at high speeds and high loads, a waste gate valve (not shown) in the bypass passage that bypasses the turbocharger 12 is opened to bypass the exhaust gas and cause the exhaust gas to leak, thereby exhausting the exhaust passage. There is no need to reduce the gas pressure, and the effective use of exhaust gas energy can be improved.

On the other hand, an energy recovery device 30 linked to the turbine 15 recovers the rotational force of the turbine 15 as motive power or electric power. In this embodiment, an alternator is employed as the recovery device 30, so that exhaust gas energy is recovered as electric power.
This recovered exhaust gas energy is used again as motive power or electrical energy. In this way, the two turbines, the turbocharger 12 and the turbine 15, efficiently recover the thermal energy of the exhaust gas and supercharge the engine E.

FIG. 4 is a p-v diagram of the turbo compound engine of this first embodiment.

In the figure, the solid line a represents the embodiment of the present invention, and the broken line b represents the embodiment of the present invention.
shows a conventional example.

In this p-v diagram, the diesel cycle D _S of engine E and the first and second turbine cycles T _S
are expressed in combination. In the diesel cycle D _S , ○A starts compression, ○B is the compression end, ○C is the heat generation period, ○knee-○ho is the expansion stroke, ○ho-○he is the blowdown period, ○h-○to is the exhaust The stroke, ○chi-○i, is the intake stroke.

Like the diesel cycle shown in conventional example b,
○He-○To-○Chi-○ during the intake and exhaust strokes becomes a large burden on the engine E when the supercharging pressure P _B is used as a reference. In particular, in conventional example b, when looking at part A in FIG. 4, that is, from near the end of the latter half of the exhaust stroke to the beginning of the intake stroke, as shown in the enlarged view of FIG. Even if the valve is in the open position at the end of the exhaust stroke, the pressure in the cylinder chamber 5 is not reduced smoothly and follows the l-p-q process as shown in the figure, and the volume of the cylinder chamber 5 is V ₁ Intake air is introduced from the position. This is because the turbocharger 12 acts as exhaust resistance and becomes a load.
As a result, a certain amount of exhaust gas remains in the cylinder chamber 5, making it difficult to introduce fresh air from the beginning of the intake stroke. On the other hand, in the embodiment a of the present invention, the sub-exhaust valve 10 is opened before the main exhaust valve 7 is closed, that is, near the top dead center (TDC) of the piston 3, as shown in FIG. That is, as shown in FIG. 4, the auxiliary exhaust passage 9 is opened at the l position near the end of the latter half of the exhaust stroke, and the intake valve (not shown) is opened at approximately the same time with a slight delay, so that the cylinder chamber is opened. 5 pressure is the turbine 1 of turbocharger 12
The inlet pressure drops to 5. That is, l-m-n in the figure
As shown in -o, the pressure is smoothly reduced, and then the intake valve is opened, so that the internal pressure of the cylinder chamber 5 rises to the supercharging pressure P _B. Therefore, when viewed as work, l-p-q-l in conventional example b is negative work as exhaust work, whereas in example a of the present invention, l-p-q-l is negative work as exhaust work.
A ₁ part formed by n-o-n and l-p-q-
The difference between the area of l and the area of p-m-n-q allows exhaust gas to be smoothly discharged from the cylinder chamber 5, and supercharged air to be transferred to the cylinder chamber 5 from the beginning of the intake stroke.
This will be a positive work that can be smoothly introduced into the future. Furthermore, it can be seen that the internal pressure of the cylinder chamber 5 is smoothly lowered from 1 to 0, so that the exhaust gas is reliably discharged and the gas exchange rate can be improved. Therefore, the filling efficiency of fresh air is stabilized,
Stable output can be obtained.

[Second Embodiment] A second embodiment of the turbo compound engine of the present invention will be described below based on the accompanying drawings. In this embodiment, a second turbocharger 15 is used instead of the turbine 15 described in the first embodiment.
Since this is an embodiment in which a reference numeral b is provided, the same reference numerals are used for structures similar to those in the first embodiment, and detailed explanations thereof will be omitted.

In the figure, 1 is the cylinder body, 2 is the cylinder liner, 3 is the piston, 4 is the cylinder head, and 5 is the cylinder liner.
is the cylinder chamber, 6 is the main exhaust passage, 7 is the main exhaust valve,
9 is a sub-exhaust passage, 10 is a sub-exhaust valve, 12 is a turbocharger, and 15b is a second turbocharger.

A main exhaust passage 6 is formed within the cylinder head 4 and communicates with the cylinder chamber 5, and is opened and closed by a main exhaust valve 7 provided within the cylinder head 4 so as to be able to reciprocate. . Further, in the cylinder head 4, a sub-exhaust passage 9 that communicates with the cylinder chamber 5 is located at a position parallel to the main exhaust passage 6.
The sub-exhaust passage 9 is opened and closed by a sub-exhaust valve 10 provided within the cylinder head 4 so as to be able to reciprocate. Exhaust manifolds are connected to the main exhaust passage 6 and the sub-exhaust passage 9, respectively, to form an exhaust system.

As shown in FIGS. 6 and 7, the exhaust manifold 11 connected to the main exhaust passage 6 is connected to the turbine scroll introduction part 12a of the turbocharger 12 as one collecting pipe. The exhaust manifold 18 of the exhaust section 14 is
It is connected to the turbine scroll introduction part 15a of the second turbocharger 15b. The exhaust section 16 of the second turbocharger 15b is connected to an exhaust manifold 17 equipped with a muffler. Therefore, the turbocharger 12 and the second turbocharger 15b are sequentially installed in the exhaust manifolds 11, 18, and 17, which are part of the main exhaust passage 6, in the downstream direction thereof.

On the other hand, the sub-exhaust passage 9 is connected to the sub-exhaust manifold 19.
The exhaust manifold 17 is connected to the exhaust manifold 17 downstream from the connection part of the second turbocharger 15b.

In FIG. 7, 25 is an intake passage, 26 is an intake manifold, and the intake passage 25 is connected to the compressor 2 of the turbocharger 12 and the second turbocharger 15b via the intake manifold 26.
Connected to 7.

The opening and closing timings of the main and auxiliary exhaust valves 7 and 10 are adjusted as shown in FIG. 3, as in the first embodiment.

As shown in the figure, the main exhaust valve 7 is opened before bottom dead center (BDC) and closed at a position beyond top dead center (TDC), whereas the auxiliary exhaust valve 10 is Before the main exhaust valve 7 is closed (for example, near the top dead center of the piston), it is opened.

The operation of the second embodiment of the turbo compound engine of the present invention will be explained below based on the accompanying drawings.

When the engine E is operated as shown in FIGS. 6 and 7, the main exhaust valve 7 is opened during the exhaust stroke, so that the exhaust gas in the cylinder chamber 5 is transferred from the main exhaust passage 6 to the exhaust manifold 11, It is discharged to the outside via 18 and 17. Next, the main exhaust valve 7
Since the sub-exhaust valve 10 is opened with a delay, the sub-exhaust passage 9 is opened and the residual exhaust gas in the cylinder chamber 5 is discharged from the sub-exhaust passage 9. That is, by opening the main and auxiliary exhaust valves 7 and 10, the entire amount of exhaust gas in the cylinder chamber 5 is discharged to the outside. This prevents the cylinder chamber 5 from becoming high in temperature, and prevents the fresh air (intake air) introduced into the cylinder chamber 5 from being heated by the heat within the cylinder 5 and the heat of the exhaust gas. therefore,
In addition to stabilizing suction efficiency, it is possible to suppress a decrease in output.

In addition, since no exhaust gas remains in the cylinder chamber 5, the air that has been sequentially supercharged by the turbocharger 12 and the second turbocharger 15b smoothly flows into the cylinder chamber 5 from the beginning of intake. In this way, the inhalation efficiency can be improved. This is turbo charger 1
2 and the second turbocharger 15b, and the workload of the second turbocharger 15b can be substantially increased. Therefore, unlike conventional methods, the waste gate (not shown) of the bypass passage that bypasses the turbocharger is opened to bypass the exhaust gas at high speeds and high loads, thereby causing the exhaust gas to leak. There is no need to reduce the pressure of exhaust gas, and exhaust gas energy can be used effectively.

In this way, the two turbines, the turbocharger 12 and the second turbocharger 15b, recover the thermal energy of the exhaust gas and the engine E.
Supercharging is carried out well.

[Effects of the Invention] As is clear from the above explanation, the turbo compound engine of the present invention can exhibit the following excellent effects.

(1) The auxiliary exhaust passage, which is opened at the end of the exhaust stroke, is connected to the downstream side of the exhaust passage, bypassing the turbocharger, so that no exhaust gas remains in the cylinder, thereby improving intake efficiency. I can do it.

(2) It is possible to stabilize the output and reduce the load on the engine.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a first embodiment of the turbo compound engine of the present invention, Fig. 2 is an overall view of the turbo compound engine of Fig. 1, and Fig. 3 is a diagram showing the opening/closing timing of the main and auxiliary exhaust valves. , Figure 4 shows the diesel cycle and turbine cycle p-v.
5 is a partially enlarged view of FIG. 4, FIG. 6 is a schematic diagram showing a second embodiment of the turbo compound engine of the present invention, FIG. 7 is an overall view of the turbo compound engine of FIG. 6, FIG. 8 is a schematic diagram showing a conventional two-stage supercharged internal combustion engine. In the figure, 6 is a main exhaust passage, 9 is a sub-exhaust passage, 12
15 is a turbocharger, 15 is a turbine for exhaust gas energy recovery, and E is an engine.

Claims (1)

[Claims] 1. A turbine for turbocharging and exhaust gas energy recovery is connected in series to the main exhaust passage of the engine, and a sub-exhaust passage is opened to the main exhaust passage downstream of the turbine after the main exhaust passage. A turbo compound engine characterized by connecting. 2. The turbo compound engine according to claim 1, wherein the auxiliary exhaust passage is configured to be opened at the end of the exhaust stroke.