KR20110086617A - Two-staged charging system for exhaust gas recirculation - Google Patents

Abstract

According to an embodiment of the present invention, a supercharging system for an internal combustion engine is provided, in which the supercharging is formed in two stages, wherein the EGR turbocharger operates in parallel with the high pressure turbochargers. The two-stage supercharging entails an improvement in the supercharging efficiency, which causes the EGR compressor to overcome the higher pressure differential.

Description

Two-stage supercharging system for exhaust gas recirculation {TWO-STAGED CHARGING SYSTEM FOR EXHAUST GAS RECIRCULATION}

The present invention relates to the field of supercharged internal combustion engines. In particular, the present invention relates to a supercharging system for an internal combustion engine, an internal combustion engine having such a supercharging system, a vehicle having such an internal combustion engine, a method for supercharging an internal combustion engine with a supercharging system, a program element, and a computer readable medium. .

Exhaust gas recirculation (EGR) is a known method for reducing NOx emissions in internal combustion engines. In supercharged engines, the high pressure deformation, ie the exhaust withdrawal upstream of the turbine of the turbocharger, and the mixing of gas downstream of the compressor, are the most energy-efficient variants. It is very widespread in the area of small engines, especially for passenger car and van applications. The reason is that the exhaust gas pressure upstream of the turbine in a wide range of engine characteristic curves is higher than the pressure of the boost air downstream of the turbocharger compressor.

This is not the case with large engines, since in most cases a positive pressure differential occurs between the conditions upstream and downstream of the cylinder through high efficiency of supercharging. This is desirable for engine operation, because this allows the combustion chamber to be evacuated and the supercharge operation reduced.

Both pressure differentials make EGR impossible without further measures. The problem can be solved by using a blower for increasing the pressure of the gas (US5657630A1). This solution solves the problem, but has the disadvantage that the blower has an electric or mechanical drive, which becomes very large and consumes a considerable amount of driving power, which negatively affects the energy balance of the overall system.

Another solution is known from DE 44 36 732 A1, in which the blower is driven by a gas turbine. The machine for the EGR then looks like a turbocharger, even if special components are applied. This solution was studied in a research project and proved to be the best thermodynamic variant (CIMAC Paper: H. Stebler et al.'Reduction of NOx-emissions of a medium-speed di diesel engine using miller system, exhaust gas recirculation, variable nozzle turbo charger and common rail fuel injection-Copenhagen 1998).

The big problem with this recirculating turbocharger is that the compressor must handle a relatively large mass flow rate with a very small pressure ratio and the turbine must handle a small mass flow rate with a large expansion ratio as much as possible.

0.9 (DT = 터빈 지름, DV = 압축기 지름) 를 갖고, 터빈의 런 수 (run number) 는 0.2 보다 작게 발생할 것이다. 터빈 런 수는 터빈의 원주 속도 uT 와, 존재하는 엔탈피 차이에 상응하는 등엔트로피 속도 c0 간의 비율이다. 이 런 수는 최적의 터빈 효율을 위해 대략 0.7 에 달해야 한다. 0.2 미만의 값에 있어서는 터빈 효율이 매우 낮다.This results in mismatching of the components. Normal diameter ratio DT / DV for turbocharger

With 0.9 (DT = turbine diameter, DV = compressor diameter), the run number of the turbine will occur less than 0.2. The turbine run number is the ratio between the circumferential speed uT of the turbine and the isentropic speed c0 corresponding to the difference in enthalpy present. This number should be approximately 0.7 for optimum turbine efficiency. At values below 0.2, the turbine efficiency is very low.

The situation can be improved by increasing the ratio DT / DV. However, this has a limitation: the reduction of the compressor diameter leads to too large values of the specific flow rate of the compressor V / Dv2, V = volume flow rate.

Increasing the turbine diameter results in too low values of the specific flow rate of the turbine, Seff / DT2, Seff = effective surface of the nozzle, equivalent to the turbine.

In both cases, the achievable efficiency of the component (compressor or turbine) is reduced.

Another improvement is known from DE 44 36 732 A1: if two EGR turbochargers are used and the turbines are arranged in series, while the compressors are operated in parallel, the problem of mismatching becomes partially severe (the number of runs of the turbines). Double).

It is an object of the present invention to provide an improved supercharging of an internal combustion engine.

According to the features of the independent claims, there is provided a charging system for an internal combustion engine, an internal combustion engine, a vehicle, a method, a program element, and a computer readable medium. Improvements of the invention are indicated in the dependent claims.

The described embodiments likewise relate to a supercharge system, an internal combustion engine, a vehicle, a method, a program element, and a computer readable medium. In other words, the features described below, for example in connection with a supercharged system, an internal combustion engine or a vehicle, can be applied to methods, program elements, and computer readable media, and vice versa.

According to an embodiment of the present invention, there is provided a charging system for an internal combustion engine, said charging system having a first turbocharger, a second turbocharger and a recirculation path. The first turbocharger has a first turbine and a first compressor, and the second turbocharger has a second turbine and a second compressor. The two turbochargers are connected in series with each other. The recirculation path is used to recycle the exhaust gas of the internal combustion engine from the outlet or exhaust receiver of the internal combustion engine to the intake or intake receiver of the internal combustion engine. In addition, an exhaust gas compressor is arranged in the recirculation path, which exhaust gas compressor is used to increase the pressure of the exhaust gas before the exhaust gas is supplied back to the intake of the internal combustion engine. To drive the exhaust compressor, the charging system has a third turbine, the third turbine connected in parallel with the second turbine of the second turbocharger, and exiting from the third turbine. Exhaust gas flow is supplied to the first turbine of the first turbocharger.

In other words, the supercharge is formed in two stages, where the EGR turbocharger works in parallel with the high pressure turbochargers. The two stage supercharging entails an improvement in the charging efficiency, which also has the side effect that the EGR compressor must overcome the higher pressure differential.

According to another embodiment of the invention, the exhaust gas compressor is a second compressor of a second turbocharger.

According to this embodiment of the invention, the EGR flow is withdrawn from the exhaust receiver and mixed after entering the main flow high pressure compressor after conditioning (cooling, washing, filtering, ...).

According to another embodiment of the invention, the charging system has a third turbine for driving the exhaust gas compressor, the third turbine being arranged in the recirculation path.

According to this embodiment of the invention, the EGR turbocharger is shorted. The EGR flow is first expanded into the turbine of the recycle charger, after which conditioning (cooling, washing, filtering, ...) is performed, followed by compression in the compressor of the recycle charger.

According to another embodiment of the invention, the charging system further comprises a power turbine, which is integrated into the recirculation path.

According to another embodiment of the present invention, at least one of the turbines has a variable adjustable flow surface.

For example, the power turbine has a variable flow surface. In addition, according to another embodiment of the present invention, a connection is provided between an outlet of an EGR turbine and an outlet of a system for regulating the turbine output. Regulation is carried out via the corresponding regulator.

According to another embodiment of the invention, at least two turbochargers operate in parallel with one another as low pressure stages.

At this time, according to another embodiment of the present invention, at least one of the low pressure turbochargers corresponds to an approximately EGR ratio and has a capacity that can be switched off by valves.

According to another embodiment of the present invention, the valve timing of the internal combustion engine is variable. According to another embodiment of the present invention, through the variable valve timing of the internal combustion engine in the operation with EGR, a smaller Miller effect is realized than in the operation without EGR.

According to another embodiment of the present invention, the system is designed such that, through variable valve timing of the internal combustion engine in operation with EGR, higher air output, ie improved scavenging, is realized than in operation without EGR. It is.

According to another embodiment of the invention, the charging system further comprises a first variable bypass line for connecting the outlet of the second compressor with the inlet of the second turbine.

According to another embodiment of the invention, the charging system further comprises a second variable bypass line for connecting the outlet of the second compressor with the inlet of the first turbine.

According to another embodiment of the invention, the charging system has a third variable bypass line for connecting the outlet of the first compressor with the inlet of the first turbine.

According to another embodiment of the invention, the charging system has a fourth variable bypass line for connecting the inlet of the second turbine with the outlet of the second turbine.

According to another embodiment of the invention, the charging system has a fifth variable bypass line for connecting the inlet of the second turbine with the outlet of the charging system.

According to another embodiment of the invention, the charging system has a sixth variable bypass line for connecting the inlet of the first turbine with the outlet of the charging system.

Note that the various variable bypass lines can be provided individually or in various combinations with one another. Corresponding control valves or regulating valves may be provided in, before, or after the bypass lines to change the bypass lines.

According to another embodiment of the invention, the low pressure compressor (first compressor) is provided with a variable diffuser.

According to another embodiment of the present invention, the low pressure compressor has an adjustable device for generating a free swirl.

According to another embodiment of the present invention, the turbine (third turbine) of the recycle charger has an adjustable flow surface.

According to another embodiment of the present invention, the high pressure turbine has an adjustable flow surface, and according to another embodiment of the present invention, the low pressure turbine has an adjustable flow surface.

According to another embodiment of the invention, the gas flow in the fourth bypass line is expanded in the power turbine.

According to another embodiment of the present invention, this power turbine has a variable flow surface.

According to another embodiment of the present invention, the gas flow in the fifth bypass line is expanded in the power turbine.

According to another embodiment of the present invention, this power turbine has a variable flow surface.

According to another embodiment of the present invention, the gas flow in the sixth bypass line is expanded in the power turbine.

According to another embodiment of the invention, this power turbine also has a variable flow surface.

According to another embodiment of the invention, the high pressure turbocharger (second turbocharger) has a mechanical connection for power take-in / power take-out.

According to another embodiment of the invention, the low pressure turbocharger (first turbocharger) has a mechanical connection for power transmission.

According to another embodiment of the present invention, there is provided an internal combustion engine having the supercharging system described above. This internal combustion engine is in particular a large engine which is used, for example, to drive a ship or locomotive or for stationary current generation in a power plant.

According to another embodiment of the present invention, there is provided a vehicle having the internal combustion engine described above for driving the vehicle.

The vehicle is, for example, a ship, a locomotive or a city running heavy vehicle.

According to another embodiment of the present invention, there is provided a method for supercharging an internal combustion engine with a supercharging system (as described above), in which the internal combustion engine is divided by two turbochargers arranged in series. It is only supercharged. In addition to this, recirculation of the exhaust gas of the internal combustion engine is performed from the discharge portion of the internal combustion engine to the intake portion of the internal combustion engine via the recirculation path. In addition to this, the compressor disposed in the recirculation path is driven. The drive of the compressor is carried out via a turbine. Through the compressor, the pressure of the exhaust gas is increased during recirculation.

In addition to this, according to another embodiment of the present invention, the adjustment of the output of one or several of the turbines is performed based on the connection between the outlet of the turbine and the outlet of the charging system.

The target variables for the regulation of the supercharging system are as follows:

-EGR amount:

The EGR amount can be carried out in virtually all cases via the regulating valve 23 or through the surface of the turbine 24 (mass flow rate through the turbine determines the turbine output). Compressor output is generated from this, and thereafter, the amount of recycled exhaust gas is generated.

Exceptions: the system of FIG. Here, the adjustment is carried out via the valve 26 and optionally via the power turbine surface 202. System of FIG. 3: Here, the valve 302 is used only in the start stage, as the case may be.

-Boost pressure (pressure in the exhaust gas receiver (1)):

The boost pressure can be influenced or regulated through sequential charging, through the variable flow surfaces of the turbines 7 and 15, or by various wastegate or power turbine variants.

-Position within the compressor characteristic curve:

The position of the operating point within the compressor characteristic curve can be influenced or adjusted by sequential charging, valve timing, variable compressor geometry, bypass valves.

The two variables are not independent: the movement of the operating points gives a change in the boost pressure, in particular a change in the boost pressure caused by a change in the pressure split between the stages results in a shift in the characteristic curves.

-Cylinder filling (air ratio and compression pressure affect the maximum cylinder pressure at constant injection);

Cylinder filling can be changed, among other things, via variable valve timing.

For example, in the adjustment of all four adjustment parameters mentioned, four adjustment circuits may be separate and pure on / off adjustments for one or several of these variables may be provided.

According to another embodiment of the present invention, a program element is provided, which instructs the processor to execute the method steps described above when the program element is executed in the processor.

The computer program element may, for example, be part of software, which is stored in the processor of the vehicle management system. The processor may likewise be a subject of the present invention. In addition to this, this embodiment of the present invention already includes a computer program element which uses the present invention from the beginning, and also includes a computer program element which allows the use of the present invention in an existing program through an update.

According to another embodiment of the present invention, there is provided a computer readable medium having stored thereon a program element, which instructs the processor to execute the method steps described above when the program element is executed in the processor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 shows a supercharging system with an EGR turbocharger in parallel to a high pressure charger according to an embodiment of the invention.
2 shows a supercharging system with EGR compression in a high pressure compressor according to another embodiment of the present invention.
3 shows a supercharging system with an EGR turbocharger in parallel to a high pressure charger according to another embodiment of the present invention.
4 shows a supercharging system according to another embodiment of the invention with an EGR turbocharger in parallel to a high pressure charger, where the ND charger is in a resistor circuit.
5 shows a supercharging system according to another embodiment of the invention with an EGR turbocharger parallel to a high pressure charger with first adjustable possibilities.
6 shows a supercharging system according to another embodiment of the invention with an EGR turbocharger parallel to a high pressure charger with second adjustable possibilities.
7 shows two vehicles according to embodiments of the invention.
8 shows a power plant with an internal combustion engine according to an embodiment of the invention.
9 shows a flowchart of a method according to an embodiment of the invention.

The figures in the figures are schematic and are not to scale.

In the following description of the drawings, the same reference numerals are used for the same or similar elements.

1 shows a supercharging system 100 with EGR turbochargers 24, 34, 29 arranged in parallel to the high pressure chargers 18, 33, 15.

An internal combustion engine 2 is provided, which has an air intake receiver 1 and an air exhaust receiver or an exhaust gas receiver 3. The high pressure gas turbine 15 of the high pressure turbocharger is connected to the exhaust gas receiver 3 via the line 5. In parallel to this, a control valve 23 (each turbine can be switched off or regulated via the control valve) via lines 5, 22, and for the EGR compressor 29 The gas turbine 24 is connected. In parallel with this, in addition, an EGR compressor 29 and a module 27 connected upstream thereof and connected to the exhaust gas receiver 3 for washing and cooling the EGR gas are connected upstream of the module. The control valve 26 is connected.

That is, the exhaust gas flow is divided into three partial flows. The first partial flow drives the high pressure turbine 15, and is then supplied to the second exhaust gas receiver (medium pressure) 4 via line 16. The second partial flow drives the recycle turbine 24 and is likewise supplied to the second exhaust gas receiver via line 25. The third partial flow is supplied to the compressor 29 of the EGR turbochargers 24, 34, 29. Reference numerals 33 and 34 denote corresponding drive shafts between the respective turbines and compressors.

Compressed exhaust gas flow is supplied via line 30 to an optionally provided EGR cooler 31. Via line 41, the resulting compressed exhaust gas flow is supplied to the air receiver 1. In order to improve operational safety, a check valve 101 may be provided in line 41.

The exhaust gas flow from the second exhaust gas receiver 4 is supplied to the low pressure turbine 7 via the line 6, and then discharged outward through the line 8, or connected downstream. For example, it is passed to or in communication with a system for exhaust aftertreatment for heat recovery.

Via line 9, air intake into the system is performed. Line 9 supplies air to the low pressure compressor 10, which is connected to the low pressure turbine 7 via a connecting shaft 32. Air blown out of the compressor 10 is passed to the air cooler 12 via the line 11, which passes the resulting cooled air to the high pressure compressor 18 via the line 11. The air discharged from the high pressure compressor 18 is passed to the other air coolers 21 via the line 19 and then supplied to the air receiver 1 through the extension of the line 19.

The preferred solution of the problem underlying the present invention is to form the supercharge in two stages, and to allow the EGR turbocharger to work in parallel with the high pressure turbochargers. The two stage supercharging entails an improvement in the charging efficiency, which also has the side effect that the EGR compressor must overcome the higher pressure differential.

On the other hand, the EGR turbine operates with a lower expansion ratio because it expands the gas only from the pressure in the exhaust gas receiver to the pressure at the inlet of the low pressure turbines.

Both effects allow the mass flow rate to lie in a more favorable ratio on the compressor side and on the turbine side, as a result of which the run number of the turbine likewise rises towards the optimum range.

A further advantage is that the residual energy of the gas used to drive the EGR turbine can continue to be used into the low pressure turbine (ND turbine).

The system allows to operate the engine with a high EGR ratio and nevertheless allow to supercharge and maintain the high efficiency of the engine. This is due to the good efficiency of the two stage supercharging and the good efficiency of the recycle charger. By mitigating the run-time problem, the cost for recycle chargers can be reduced because already known components can be used, while in the case of first-stage supercharging, new development with extreme target values will be needed.

The advantages of two-stage supercharge over the one-stage supercharge need not be described specifically here. Two-stage supercharging with intermediate cooling has a much higher efficiency and allows to reach even higher pressure ratios of supercharging. This generally means higher efficiency for the engine, as well as the potential for improved performance, especially emissions reduction through the Miller process, and higher flexibility for regulation. All these advantages can be obtained with the proposed system.

2 shows the supercharging system 100 with EGR compression in the high pressure compressor 18. Line 28 is provided, which supplies a portion of the exhaust gas flow from the exhaust gas receiver 3 to the power turbine 202 via a valve 26 for switching off the EGR path. Thereafter, the exhaust gas flow from the power turbine 202 reaches the cleaning module 27, which is also used to cool the EGR gas. The washed and cooled exhaust gas then reaches high pressure compressor 18 via lines 201 and 11.

In this embodiment of the invention, the compressor of the high pressure charger is additionally used as a compressor for the recycle flow. The EGR flow is withdrawn from the exhaust receiver and mixed with the main flow after conditioning (cooling, washing, filtering, ...) in front of the inlet of the high pressure compressor. The advantage of this implementation is that the EGR turbocharger is eliminated, which makes the system simpler. Power turbines are not essential for the function of this implementation. In a simplified implementation-without a power turbine-the expansion energy of the EGR gas from the inlet pressure of the high pressure turbine to the inlet pressure of the high pressure compressor is not used: the gas is shut off only in the valve 26. For very large engines, this expansion energy may not be slight, so the integration of the power turbine into the EGR path turns out to be an interesting option. In order to improve the controllability of the system, it is also advantageous if the power turbine has a variable flow surface.

3 shows a supercharge system 100 in parallel with the high pressure chargers 18, 33, 15 and with a short-circuit EGR turbocharger. The washed and cooled EGR gas flow through module 27 (such as a so-called scrubber, cooler or heat exchanger) is fed to compressor 29 via line 301. At the same time, a portion of the exhaust gas flow may be supplied outward through the valve 302 or may be supplied to a system connected downstream, which is connected.

In this embodiment of the invention, the recycle turbocharger is shorted. The EGR flow is first expanded into the turbine of the recycle charger, after which conditioning (cooling, washing, filtering, ...) is performed, followed by compression in the compressor of the recycle charger. This implementation requires a higher pressure ratio of the EGR compressor, for which gas flow for driving the EGR turbine can be saved. For starting up the machine, and also for performance control, the possibility of raising the mass flow of the turbine via an adjustable blow-off valve 302 is appropriately provided.

There are application cases where it is advantageous to drive the engine without EGR, for example for marine engines. In this case, the high pressure turbocharger can continue to operate without problems. However, low pressure chargers will experience large shifts in the operating point within the compressor characteristic curve. In order to limit the efficiency loss of the compressor, a design is provided at a very suitable pressure ratio for the low pressure charger such that the characteristic curve width still exists.

In order to enable engine operation with or without EGR, additional variability is present in the supercharging system.

The first possibility is to divide the total capacity among the plurality of low pressure turbochargers. One of the low pressure turbochargers has a capacity almost equal to the EGR ratio, and is only active in the register circuit when the EGR is switched off. In this case, supercharging can provide comparable values of the boost pressure and efficiency in both modes of operation.

Another possibility is to vary the valve timing of the engine. Many of today's engines run on so-called Miller processes. This is achieved in a four-stroke engine earlier or later than the angle with optimum filling, through the closing of the intake valve, so that the cylinder obtains much less supercharge than the mass corresponding to the density and stroke volume in the intake receiver. Can be. This can be produced for a two-stroke engine by closing the discharge valve later. It is particularly preferable if the Miller effect in the operation with EGR is smaller than in the operation without EGR. This can reduce movement of the operating point within the compressor characteristic curve. In addition, the reduction in filling in operation without EGR allows to reduce the increase in the air ratio and the maximum cylinder pressure due to higher boost pressure. In particular, in a four-stroke engine, the permeability of the engine, i.e., the relationship between the boost pressure and the output, can be further affected by the change in the valve overlap.

The flow surfaces of the turbines are designed such that the flow surfaces give drive power to the compressors in order to generate the required boost pressure in operation with EGR. Turbines gain more mass during operation without EGR, and thus produce more power. To reduce this power, there are several possibilities:

-Provide a variable flow surface for the high pressure turbine.

Providing a variable flow surface for the low pressure turbine.

Providing a high-pressure waste gate, ie a bypass line, around the high-pressure turbine.

Providing a low pressure-waste gate, ie a bypass line, around the low pressure turbine.

Providing a system-waste gate, ie a bypass line, around the two turbines.

The variable turbine face allows to reduce the turbine output with the least efficiency loss. This loss is higher with the high-pressure gate, and even higher with other waste gate variants.

Excess exhaust energy in operation without EGR can be transferred into the power turbine once it is integrated into the turbine bypass line. In order to improve the controllability of the system, it is also advantageous if the power turbine has a variable flow surface. Alternatively, excess power can be taken straight out of the turbocharger shaft. If there is a connection to the turbocharger shaft, the connection may be used as a power take-in, i.e. external power may be supplied when necessary.

The problem of movement of operating points within the compressor characteristic curve can be expressed as:

If the compressors are designed for optimal operation with EGR, they operate with too large volume flow and too high pressure during operation without EGR; This results in worse efficiency and, in some cases, exceeding the absorption limit or rotational speed limit of the compressor.

If compressors are designed for optimal operation without EGR, they operate with too little volume flow and too little pressure during operation with EGR; This can lead to an excess of the pumping limit.

Bypass lines around the engine can help prevent pumping. This bypass line can be represented as a connection:

-From the high pressure compressor to the high pressure turbine (HD bypass).

-From the low pressure compressor to the low pressure turbine (ND bypass).

-From the high pressure compressor to the low pressure turbine (HD / ND bypass).

The geometry of the variable compressor is another possibility of shifting the optimum operating range of the compressor. The advantage is that less energy can be consumed for compression compared to bypass variants. The variability can preferably be used in low pressure compressors, and can be realized as follows:

Variable (rotatable) diffuser vanes.

An adjustable device for generating swirl at the compressor inlet.

4 shows a supercharge system 100 with an EGR turbocharger connected in parallel to a high pressure charger, in which the low pressure chargers 10, 32, 7 are designed in a resistor circuit. The turbine 36 is connected to the second exhaust gas receiver 4 via a line 13 and a valve 14 (for switching off respective cabins). The released gas flow is released externally via line 37 or to a system connected downstream. The turbine 36 is connected with the compressor 38 via the shaft 35. Compressor 38 is supplied with air, for example from outside, via line 17. The compressed air is supplied from the compressor 38 to the air cooler 40 via the valve 20 and then to the high pressure compressor 18 via the line 39 and the line 11.

The cooled air of the low pressure compressor 10 produced through the air cooler is likewise supplied to the high pressure compressor 18 via line 11.

5 shows a supercharge system 100 with an EGR turbocharger in parallel to a high pressure charger with first adjustable possibilities. Multiple variable bypass lines 501-506 are provided. The bypass line 501 is connected between the outlet of the high pressure compressor and the inlet of the high pressure turbine 15. The variable bypass line 502 is connected between the outlet of the high pressure compressor 18 and the inlet of the low pressure turbine 7. The variable bypass line 503 is connected between the outlet of the low pressure compressor 10 and the inlet of the low pressure turbine 7. The variable bypass line 504 is connected between the inlet of the high pressure turbine 15 and the outlet thereof. The variable bypass line 505 is connected between the inlet of the high pressure turbine 15 and the outlet of the low pressure turbine 7. Variable bypass line 506 is connected between the inlet and the outlet of the low pressure turbine. The variable bypass lines have corresponding control valves.

In addition to this, the control valve 507 is connected between the power turbine 508 and the second exhaust gas receiver 4.

The second power turbine 509 is connected to the line 5 via a variable line 510 with a corresponding control valve.

Variable bypass lines 504-506 are optional if corresponding power turbines are installed.

6 shows a supercharge system 100 with an EGR turbocharger in parallel to a high pressure charger with second adjustable possibilities. For example, air is discharged from the power turbine 509 outwards (system outlet) or to a system connected downstream, and not supplied to the second exhaust gas receiver. Reference numerals 601, 602 denote Power take-in / Power take-out (PTI / PTO) connections of two turbochargers 18, 33, 15 and 10, 32, 7.

Reference numerals 203, 511, 512, 601, 602 in FIGS. 2, 5 and 6 denote generators or engine / generators, respectively. It relates to loads for power turbines or PTI / PTOs, ie generators or electric engines / generators, gears, pumps or hydraulic pumps / turbines for connection with the crankshaft of the engine.

Reference numerals 303 in FIGS. 3, 5 and 6 indicate the exit of the system which is guided outward or connected with the system connected downstream.

The engine 2 has variable valve timing in other embodiments in FIGS. 5 and 6.

7 shows two vehicles according to embodiments of the invention. The first vehicle 601 is a ship and the second vehicle 602 is a locomotive, which vehicles in each case are equipped with a large engine with a supercharging system 100 according to the invention.

8 shows a power plant 700 with a charging system 100 provided for a power plant large engine.

9 shows a flowchart of a method according to an embodiment of the invention.

In step 901, two stage supercharging of the internal combustion engine by two turbochargers arranged in series is performed. By driving the compressor disposed in the recirculation path through the turbine in step 902, recirculation of the exhaust gas of the internal combustion engine from the outlet of the internal combustion engine to the inlet of the internal combustion engine is carried out via the recirculation path, step 903. In this case, the pressure rise of the exhaust gas during recirculation through the compressor is performed.

In the embodiments described above, the resistor circuit of low pressure compressors is particularly preferred. In addition, it should be noted that the features or steps described in connection with any of the above embodiments may be used in combination with other features or steps of the other embodiments described above. Prioritizing system efficiency, or cost or diversity, is critical to the choice of the appropriate solution in each case.

Note also that 'comprising' and 'comprising' do not exclude other elements or steps, and 'one' does not exclude a plurality. Reference signs in the claims should not be considered limiting.

1: air receiver
2: internal combustion engine
3: exhaust gas receiver
4: second exhaust gas receiver (medium pressure)
5, 6, 13, 22: connection from the exhaust gas receiver to the turbine inlet
14, 23: valve for switching off each turbine
7, 15, 24, 36: gas turbine
8, 37, 303: Connection to downstream connected systems (heat recovery, exhaust gas aftertreatment, communication, ...)
16, 25 connection from the turbine outlet to the intermediate pressure exhaust gas receiver
9, 17: air inlet into the system
10, 18, 29, 38: compressor
19: Connection from the compressor outlet to the air receiver
11. 39 connection from the compressor outlet to the high pressure compressor
12, 21, 40: air cooler
20: valve for switching off the compressor
26: valve for switching off the EGR path
27: Module for cleaning and cooling EGR gas (scrubber, cooler, heat exchanger, ...)
28, 201: connection from the exhaust gas receiver to the EGR compressor
30, 41: connection from the EGR compressor to the air receiver
31: EGR cooler (optional)
32, 33, 34, 35: turbocharger or connecting shaft between turbine and compressor
202, 508, 509: power turbine
501 to 506: variable bypass line with valves
507, 510: variable line with valves
203, 511, 512, 601, 602: generator or engine / generator
101: check valve
302: control valve

Claims (14)

As a two-stage supercharging system for an internal combustion engine, the supercharging system 100
Low pressure turbochargers 7, 10 having a first turbine 7 and a first compressor 10;
High pressure turbochargers 15, 18 having a second turbine 15 and a second compressor 18;
The low pressure turbochargers 7, 10 are then arranged in series with respect to the high pressure turbochargers 15, 18, so that the exhaust gas flow from the second turbine 15 is controlled by the first turbochargers 7, 10. 1 is supplied to the turbine 7,
A recirculation path 28, 30, 41, 201 for recycling the exhaust gas of the internal combustion engine 2 from the discharge part 3 of the internal combustion engine 2 to the intake part 1 of the internal combustion engine 2;
Disposed in the recirculation paths 28, 30, 41, 201, and having exhaust gas compressors 18, 29 used to increase the pressure of the exhaust gas,
At this time, the exhaust gas compressor 24 is driven by the third turbine 24, which is connected in parallel to the second turbine 15 of the high pressure turbochargers 15 and 18, and thus A two-stage supercharge system for an internal combustion engine in which the exhaust gas flow from the three turbines (24) is fed to the first turbine (7) of the low pressure turbocharger (7, 10). 2. The supercharging system according to claim 1, wherein the exhaust gas compressor (18) is a second compressor (18) of a second turbocharger (15, 18). 2. The supercharging system according to claim 1, wherein the third turbine (24) is arranged in the recirculation path (28, 30, 41, 201). The method of claim 1,
The charging system further comprises a power turbine (202) integrated into the recirculation path (28, 30, 41, 201). The charging system for an internal combustion engine according to claim 1, wherein the charging system further comprises at least one element selected from the group consisting of:
A first variable bypass line 501 for connecting the outlet of the second compressor 18 with the inlet of the second turbine 15;
A second variable bypass line 502 for connecting the outlet of the second compressor 18 with the inlet of the first turbine 15;
A third variable bypass line 503 for connecting the outlet of the first compressor 10 with the inlet of the first turbine 7;
A fourth variable bypass line 504 for connecting the inlet of the second turbine 15 with the outlet of the second turbine 15;
A fifth variable bypass line 505 for connecting the inlet of the second turbine 15 with the outlet 8 of the charging system; And
Sixth variable bypass line (506) for connecting the inlet of the first turbine (7) with the outlet (507) of the charging system. The charging system for an internal combustion engine according to any one of claims 1 to 5, wherein the valve timing of the internal combustion engine is variable. 7. The supercharging system according to any one of the preceding claims, wherein at least one of the turbines or one of the compressors or the power turbine has at least one variable element. 8. Charging system according to any one of the preceding claims, which is designed for sequential charging. An internal combustion engine having a supercharging system according to any one of claims 1 to 8. A vehicle having an internal combustion engine according to claim 9 for driving a vehicle. A method for supercharging an internal combustion engine with a supercharging system, the method comprising:
Supercharging the internal combustion engine 2 in two stages by means of two exhaust gas turbochargers arranged in series, wherein the second turbine 15 of the high pressure turbochargers 15, 18 in the exhaust gas turbochargers. Exhaust gas flow from the supercharged internal combustion engine 2 in two stages, supplied to the first turbine 7 of the low pressure turbocharger 7, 10;
Recycling the exhaust gas of the internal combustion engine 2 from the outlet 3 of the internal combustion engine 2 to the intake 1 of the internal combustion engine 2 via a recirculation path;
Driving the compressor disposed in the recirculation path by the turbines 7, 15, 24 arranged in parallel to the second turbine 15 of the second exhaust gas turbocharger 15, 18;
Increasing the pressure of the exhaust gas upon recirculation by the compressor. 12. The method according to claim 11, wherein the method further comprises adjusting the amount of exhaust gas through the recirculation path and / or the boost pressure in the exhaust gas receiver (1). As a program element, the program element instructs the processor to execute the following steps when the program element is executed in the processor to control the supercharging system according to any one of the preceding claims:
Adjusting the amount of exhaust gas through the recirculation path and / or the boost pressure in the exhaust gas receiver 1. A computer readable medium having stored thereon a program element on a computer readable medium, the program element being executed by a processor to control the supercharging system according to any one of claims 1 to 8. Computer-readable media that instructs the processor to execute the following steps:
Adjusting the amount of exhaust gas through the recirculation path and / or the boost pressure in the exhaust gas receiver 1.

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