Intercooler, air supply system and internal combustion engine

Abstract

The invention relates to an intercooler (14) for an internal combustion engine (10), comprising an air inlet (42) for charge air, a heat exchanger (36) for temperature control of the charge air, and an air outlet (44). It is characterized in that an expansion turbine (38) is arranged downstream of the heat exchanger (36) in the direction of charge air flow. The invention further relates to an air supply system (13) and an internal combustion engine (10). The invention enables additional cooling of exhaust gases in a space-saving manner.

Description

[0001] The present invention relates to an intercooler for an internal combustion engine, comprising an air inlet for charge air, a heat exchanger for temperature control of the charge air, and an air outlet. The invention further relates to an air supply system and an internal combustion engine with an air supply system. State of the art

[0002] Patent EP 1 888 893 B1 discloses an internal combustion engine, an exhaust system and an air supply device, wherein the air flowing into the internal combustion engine is compressed by a turbocharger and cooled in two cooling stages before being introduced into the combustion chambers of the internal combustion engine.

[0003] The patent application US 2017 / 0022884A1 describes an internal combustion engine, an exhaust system and an air supply device, wherein the air flowing into the internal combustion engine is compressed by two turbochargers and cooled by an intercooler.

[0004] A turbocharger with a heat exchanger is known from patent US 6 805 108 B2.

[0005] A compressor with a heat exchanger is known from the translation document DE 11 2004 001 703 T5.

[0006] Patent EP 3 244 033 B1 describes a coolant-cooled turbocharger with a turbine wheel, a compressor wheel and an electric motor.

[0007] International patent application WO 2009 / 080 086 A1 discloses an internal combustion engine with two turbocharger systems, wherein a second turbocharger of a second turbocharger system has a variable geometry. Disclosure of the invention

[0008] Modern combustion engines tend to produce higher exhaust gas temperatures. However, higher exhaust gas temperatures can shorten the lifespan of components along the exhaust path, such as exhaust valves or catalytic converters. Furthermore, increasingly complex and space-consuming technology is employed to meet current efficiency and performance requirements. Consequently, modern vehicles offer very little free space in the engine compartment for accommodating additional components.

[0009] The object of the present invention is therefore to offer devices for an internal combustion engine and an internal combustion engine that enable low exhaust gas temperatures with a small additional space requirement.

[0010] The problem is initially solved by an intercooler for an internal combustion engine, comprising an air inlet for charge air, a heat exchanger for temperature control of the charge air and an air outlet, wherein an expansion turbine is arranged behind the heat exchanger in the direction of flow of the charge air.

[0011] The heat exchanger can preferably be configured to cool the charge air.

[0012] The expansion turbine enables an additional reduction in charge air pressure. This allows the charge air to be boosted more effectively by an exhaust gas turbocharger installed upstream of the intercooler than would otherwise be possible without the expansion turbine. Consequently, the upstream turbocharger can extract more energy from the incoming exhaust gas to increase the charge air pressure. The exhaust gas can thus be cooled more effectively than would otherwise be possible, resulting in lower exhaust gas temperatures. Components in the exhaust system downstream of the turbocharger, such as catalytic converters, exhaust valves, and the like, are protected, and their service life is extended.

[0013] The expansion turbine can be part of the intercooler. In particular, it can be located inside the intercooler. This allows the intercooler to have a relatively small overall volume despite the additional expansion turbine. Therefore, installing the expansion turbine requires only a small amount of additional space in the engine compartment of a vehicle where the intercooler is installed.

[0014] Additionally, the expansion turbine can generate usable energy, such as mechanical energy or – in conjunction with an electric generator – electrical energy. This usable energy can be used for other purposes. For example, it can support or even power the exhaust gas turbocharger. It is also conceivable, particularly after conversion to electrical energy, that other electrical consumers in the vehicle could be operated with this usable energy.

[0015] In the charge air cooler, a compressor wheel can be positioned upstream of the heat exchanger in the direction of the charge air flow to compress the charge air. This allows the charge air to be compressed even further before cooling in the heat exchanger. The charge air temperature can thus be increased further. The resulting increase in the temperature difference between the charge air and the coolant in the heat exchanger allows the heat exchanger's performance to be improved. Consequently, the heat exchanger can be designed to be smaller for the same heat exchanger performance, thus saving space. The space saved can then be used, for example, for the expansion turbine.

[0016] The expansion turbine and the compressor wheel can be connected to each other in a rotationally fixed manner. In particular, the charge air cooler can be configured so that the expansion turbine drives the compressor wheel. For this purpose, the expansion turbine and the compressor wheel can be arranged on a common shaft. The usable energy provided by the expansion turbine can thus be used to drive the compressor wheel.

[0017] The expansion turbine can have a variable geometry. For example, it can have an expansion turbine slide valve that allows the opening width of an inlet to be changed. This allows the pressure and temperature drop across the expansion turbine to be adjusted depending on the operating conditions of the combustion engine, the exhaust gas turbocharger, and / or the expansion turbine itself. The response of the combustion engine, including the exhaust gas turbocharger and the entire air supply system, can thus be optimized.

[0018] In a naturally aspirated combustion engine, the intake air supplied to the engine can be throttled via a throttle valve. In the device proposed here, the expansion turbine can be used for throttling. This allows the rotational speed of the expansion turbine to be increased, particularly under partial load. The expansion turbine can thus be brought up to a typical operating speed more quickly, especially during kickdown.

[0019] The heat exchanger can be cooled by a liquid coolant, such as cooling water. Compared to an air-cooled heat exchanger, a higher cooling capacity can be achieved. Consequently, for a given cooling capacity, the heat exchanger can be built smaller than an air-cooled heat exchanger.

[0020] The heat exchanger can have a multitude of coolant-flushed tubes through which charge air flows, with the tubes arranged around the shaft. Generally, the tubes can be positioned between the compressor wheel and the expansion turbine. This also allows for a compact overall design of the charge air cooler. The large number of tubes can provide a large heat exchange surface, further reducing the volume of the heat exchanger for a given power output.

[0021] The charge air cooler may additionally include a return flow channel and / or a connection for a return flow channel. The return flow channel or the connection may be located in the area of ​​the compressor wheel. Via the return flow channel, charge air compressed by the compressor wheel can be returned to the exhaust gas turbocharger, for example, during naturally aspirated operation of the internal combustion engine.

[0022] The invention further encompasses an air supply system for an internal combustion engine, comprising an intercooler of the type described above and an exhaust gas turbocharger for charging the intake air. The exhaust gas turbocharger can be connected to the intercooler for supplying intake air via an air supply line.

[0023] The exhaust gas turbocharger can charge the intake air with a particularly high boost pressure. This allows the intake air to reach a particularly high temperature. The heat exchanger can then cool the intake air with exceptional efficiency. The expansion turbine further reduces the compression of the intake air. The combustion engine can thus be supplied with intake air that is charged to a typical level, especially a typical boost pressure, despite the initially higher compression.

[0024] A return flow channel can lead from the charge air cooler to a turbine of the exhaust gas turbocharger, particularly a Pelton turbine. The return flow channel can also lead from the compressor wheel to the turbine of the exhaust gas turbocharger. The exhaust gas turbocharger can be additionally driven via the return flow channel. Depending on the operating mode of the combustion engine, it is conceivable to create a flow-related short circuit between the compressor wheel and the exhaust gas turbocharger using the return flow channel. A controllable valve can be installed in the return flow channel for this purpose. The valve can be closed when a short circuit is not desired. The valve can be open to create the short circuit.

[0025] The short circuit can be particularly desirable in a naturally aspirated combustion engine.

[0026] Furthermore, the invention relates to an internal combustion engine, particularly one from a sports car. The internal combustion engine can have an air supply system of the type described above. In this engine, the exhaust gas turbocharger can be used to extract a particularly large amount of energy from the exhaust gas, thus cooling it to a particularly low temperature. This can extend the service life of components located downstream of the exhaust gas turbocharger along the exhaust path. Since the air supply system can be compact overall, the internal combustion engine requires little or no additional space in the engine compartment where it is to be installed.

[0027] Further advantages can also be achieved through the combustion engine. For example, the behavior of the combustion engine during kick-down can be improved.

[0028] Further features and advantages of the invention will become apparent from the following detailed description of an embodiment of the invention with reference to the figures of the drawing, which show details essential to the invention, as well as from the claims.

[0029] The individual features can be implemented individually or in any combination in various versions of the invention. The schematic drawing illustrates exemplary embodiments of the invention, which are explained in more detail in the following description. Brief description of the drawings

[0030] They show: Fig. 1 a schematic representation of an internal combustion engine; Fig. 2 a schematic representation of a turbine of an exhaust gas turbocharger; Fig. 3 the internal combustion engine according to Fig. 1 in a charged state; Fig. 4 a perspective oblique view of an intercooler; Fig. 5 a schematic sectional view through the charge air cooler according to Fig. 4; Fig. 6 a schematic sectional view of an area of ​​a heat exchanger of the charge air cooler according to Fig. 4; Fig. 7 a perspective view of the heat exchanger according to Fig. 6; Fig. 8 another perspective view of the heat exchanger according to Fig. 6; Fig. 9 a schematic sectional view of the charge air cooler according to Fig. 4 in a vacuum-driven operation and Fig. 10 a schematic sectional view of the charge air cooler according to Fig. 4 in a fully charged operation.

[0031] To facilitate understanding of the following description of the figures, the same reference symbols are used for corresponding elements in the different figures. Embodiments of the invention

[0032] Error! Reference source not found. Figure 10 is a schematic representation of an internal combustion engine 10. The internal combustion engine 10 has a motor 12, which is supplied with charge air via an air supply system 13. The air supply system 13 has an intercooler 14 and an exhaust gas turbocharger 16, which is supplied with exhaust gases from an exhaust system 15. The exhaust gas turbocharger 16 has a fresh air inlet 17 through which it draws fresh air. The exhaust gases drive exhaust gas turbocharger turbines 18. Downstream of the exhaust gas turbocharger turbines 18 is an exhaust gas purification system 20. The exhaust gas purification system 20 can, for example, have one or more exhaust gas catalysts. An outlet of the exhaust gas turbocharger 16 is connected to an air inlet of the intercooler 14 via an air supply line 22.

[0033] The charge air cooler 14 is connected to the exhaust gas turbocharger 16 via a return flow channel 24. The return flow channel 24 also has a valve 26 with which the return flow channel 24 can be controllably opened or closed. The engine 12 is supplied with charge air exiting the charge air cooler 14 via engine air supply lines 28 and throttle valves 30.

[0034] Fig. Figure 1 shows a naturally aspirated operation of the internal combustion engine 10, in which the throttle valves 30 are open.

[0035] Fig. Figure 2 shows a schematic representation of area II made up of Fig. 1 with a schematic partial view of the exhaust gas turbocharger 16. A Pelton turbine 32 can be seen, which passes through the return flow channel 24 (see Fig. 1) can be driven by flowing air.

[0036] Fig. Figure 3 shows the internal combustion engine 10 in an operating mode in which the charge air is or is being charged. In the embodiment shown here, the charge air flows through the air supply line 22 at 3.5 bar and 215 °C and reaches the charge air cooler 14. A compressor wheel in the charge air cooler 14 further compresses the charge air to 5.2 bar at 275 °C. A heat exchanger in the charge air cooler 14 cools the air to approximately 53 °C at approximately the same pressure, for example, 5.1 bar. An expansion turbine in the charge air cooler 14 further expands the charge air, and it reaches the throttle valves 30 at 2.5 bar and 20 °C.

[0037] In this charged operation, the return flow channel 24 is blocked by means of the valve 26.

[0038] In naturally aspirated operation of the internal combustion engine 10, charge air is fed into the charge air cooler 14 via the air supply line 22 under typical ambient conditions, for example, 20 °C and 1 bar. The compressor wheel can contribute to at least a slight additional boost, for example, to 1.2 bar at 40 °C. The charge air can be cooled to 20 °C via the heat exchanger, for example, isobarically or at least substantially isobarically. It can be throttled to 0.3 bar via the expansion turbine, in particular isothermally or at least substantially isothermally. In this naturally aspirated operation, further throttling via the throttle valves 30 is unnecessary. The return flow channel 24 is open by means of the valve 26 in this naturally aspirated operation.

[0039] Fig. Figure 4 shows an external view of the charge air cooler 14 in a perspective oblique view.

[0040] Fig. Figure 5 shows a schematic sectional view of the charge air cooler 14 according to Fig. 4. The charge air cooler 14 comprises the compressor wheel 34, the heat exchanger 36, and the expansion turbine 38. The compressor wheel 34 is non-rotatably connected to the expansion turbine 38 via a shaft 40. The expansion turbine can thus drive the compressor wheel 34.

[0041] The structure and function of the heat exchanger 36 are described using the following examples: Fig. 6, which covers area VI according to Fig. Figure 5, shown in a schematic detail view, is explained in more detail.

[0042] The heat exchanger 36 has an air inlet 42 and an air outlet 44. Charge air flows through the heat exchanger 36 from the air inlet 42 via a plurality of cooling tubes 46 to the air outlet 44. Coolant, in particular coolant, flows on the outside of the cooling tubes 46. The coolant enters the heat exchanger 36 through a coolant inlet 48 and exits it through a coolant outlet 50.

[0043] The cooling tubes 46 can have a free inner diameter d2 of, for example, 4 mm. They can have a thickness of, for example, 1 mm and thus an outer diameter d1 of approximately 5 mm. The cooling tubes 46 can be embedded in an aluminum block 47. The aluminum block 47 can be equipped with gaps, for example, 1 mm thick, to guide the coolant. These gaps can form channels through which coolant can flow within the aluminum block 47 along the cooling tubes 46.

[0044] Fig. 7 and Fig. Figure 8 shows the heat exchanger 36 with the cooling pipes 46 in perspective oblique views, once from the side of the compressor wheel 34 (see Fig. 7) and from the side of the expansion turbine 38 (see Fig. 8).

[0045] Based on Fig. 9 and Fig. 10 The following describes the flow conditions within the charge air cooler 14 in naturally aspirated engine operation (see Fig. 9) as well as in charged operation (see Fig. 10) explained in more detail.

[0046] Charge air flows into the charge air cooler 14 via the air inlet 42. In naturally aspirated engine operation, some of the charge air can be diverted via the return flow channel 24 (see Fig. 1) to the Pelton turbine 32 (see Fig. 2) flow back. The remaining charge air is cooled via the heat exchanger 36, expands via the expansion turbine 38 and exits the air outlet 44 and passes through the throttle valves 30, the throttle valves 30 being fully open in naturally aspirated engine operation.

[0047] The turbocharged operation differs from the naturally aspirated operation primarily in that the return flow channel 24 is controlled by the valve 26 (both see Fig. 1) is blocked. Charge air entering through air inlet 42 is thus further compressed and reaches the heat exchanger 36 completely. In this, the compressed charge air is cooled and expands again via the expansion turbine 42. For further throttling, the throttle valves 30 are at least partially closed.

[0048] The geometry of the expansion turbine 38 can be varied by means of the expansion turbine slide 52. During naturally aspirated operation (see Fig. 9) The expansion turbine valves 52 are largely closed. During supercharged operation, however, the expansion turbine valves 52 can be open, for example, as in Fig. 10 shown, opposite the position according to Fig. Postponed to 9. Reference symbol list 10 Internal combustion engine 12 engine 13 Air supply system 14 Intercoolers 15 Exhaust system 16 exhaust gas turbochargers 17 Fresh air intake 18 exhaust gas turbocharger turbines 20 Exhaust gas purification system 22 Air supply line 24 Return flow channel 26 valve 28 engine air supply lines 30 Throttle valve 32 Pelton turbine 34 compressor wheel 36 heat exchangers 38 Expansion turbine 40 wave 42 Air intake 44 Air outlet 46 Cooling pipe 47 aluminum blocks 48 Coolant inlet 50 Coolant outlet 52 Expansion turbine valves d1 outer diameter d2 inner diameter Area II VI Area 1

Claims

[1] Charge air cooler (14) for an internal combustion engine (10), comprising an air inlet (42) for charge air, a heat exchanger (36) for temperature control of the charge air and an air outlet (44), wherein an expansion turbine (38) is arranged downstream of the heat exchanger (36) in the direction of charge air flow, characterized by , that in the charge air cooler (14) in the direction of flow of the charge air upstream of the heat exchanger (36) a compressor wheel (34) is arranged for compressing the charge air, wherein the charge air cooler (14) additionally includes a return flow channel (24) and / or a connection for a return flow channel (24), wherein charge air compressed by the compressor wheel (34) can be returned to the exhaust gas turbocharger via the return flow channel (24). [2] Charge air cooler according to the preceding claim, characterized by, that the expansion turbine (38) and the compressor wheel (34) are connected to each other in a rotationally fixed manner, in particular that the expansion turbine (38) and the compressor wheel (34) are arranged on a common shaft (40). [3] Charge air cooler according to any one of the preceding claims, characterized by , that the expansion turbine (38) has a variable geometry. [4] Charge air cooler according to any of the preceding claims, characterized by , that the heat exchanger (36) is cooled by a liquid coolant. [5] Charge air cooler according to any one of the preceding claims 2 to 4 in conjunction with claim 2, characterized by , that the heat exchanger has a plurality of coolant-washed cooling tubes (46) through which charge air flows, wherein the cooling tubes (46) are arranged around the shaft (40). [6] Air supply system (13) for an internal combustion engine (10), comprising an intercooler (14) according to one of the preceding claims and an exhaust gas turbocharger (16) for charging charge air, wherein the exhaust gas turbocharger (16) is connected to the intercooler (14) for supplying charge air via an air supply line (22). [7] Air supply system according to the preceding claim, characterized by , that the return flow channel (24) is led from the charge air cooler (14) to a turbine, in particular a Pelton turbine (32), of the exhaust gas turbocharger (16). [8] Internal combustion engine (10), in particular of a sports car, with an air supply system (13) according to one of the preceding claims 6 or 7.

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