Charge air system for providing charge air to an internal combustion engine

Abstract

The invention relates to a charge air system for providing charge air to an internal combustion engine, comprising at least the following components in the order mentioned along the flow direction: - a compressor turbine of a turbocharger; - an intercooler for cooling compressed charge air from the compressor turbine; - a Ranque-Hilsch vortex tube with an inlet outlet and a return outlet, wherein, during operation, an inlet flow further cooled from the cooled charge air flows out through the inlet outlet for a combustion chamber of an internal combustion engine, and a heated return flow flows out through the return outlet; and - a return flow restrictor for the return flow of the Ranque-Hilsch vortex tube. With the charge air system proposed here, efficient full-load operation of an internal combustion engine can be achieved using simple means.

Description

[0001] The invention relates to a charge air system for providing charge air for an internal combustion engine, a method with such a charge air system for cooling charge air for an internal combustion engine, an internal combustion engine with such a charge air system for a motor vehicle, and a motor vehicle with such an internal combustion engine.

[0002] In turbocharged internal combustion engines, the conflict between high specific power output and the lowest possible combustion temperature in the combustion chamber presents a challenge. One solution is to inject water into the combustion chamber to lower the combustion temperature. However, in a mobile application, such as a motor vehicle, this requires carrying water in a tank and refilling it regularly.

[0003] Based on this, the present invention aims to overcome, at least partially, the disadvantages known from the prior art. The features of the invention are defined in the independent claims, for which advantageous embodiments are shown in the dependent claims. The features of the claims can be combined in any technically meaningful way, whereby the explanations in the following description and features from the figures, which comprise supplementary embodiments of the invention, can also be used.

[0004] The invention relates to a charge air system for providing charge air to an internal combustion engine, comprising at least the following components in the order mentioned along the flow direction: - a compressor turbine of a turbocharger; - an intercooler for cooling compressed charge air from the compressor turbine; - a Ranque-Hilsch vortex tube with an inlet outlet and a return outlet, wherein, during operation, an inlet flow further cooled from the cooled charge air flows out through the inlet outlet for a combustion chamber of an internal combustion engine, and a heated return flow flows out through the return outlet; and - a return flow restrictor for the return flow of the Ranque-Hilsch vortex tube.

[0005] Unless explicitly stated otherwise, ordinal numbers used in the preceding and following descriptions serve solely for unambiguous differentiation and do not indicate any order or ranking of the components referred to. An ordinal number greater than one does not necessarily imply the presence of another such component.

[0006] The charge air path is located upstream of the intake chamber of an internal combustion engine along the flow direction from the (oxygen-rich) air to the combustion chamber of the internal combustion engine.

[0007] A turbocharger is (usually exclusively) driven by exhaust gas from the internal combustion engine, which is routed through an exhaust manifold. This utilizes the otherwise unused kinetic energy of the exhaust gas to charge the combustion chamber, i.e., to raise the intake pressure to a level above atmospheric pressure, for example, 1.5 bar to 2.5 bar. The mechanical and thermal stress on the internal combustion engine increases with the pressure, which can reduce the engine's lifespan. Higher pressures, for example, from about 3 bar upwards, can lead to engine overload, resulting in engine damage such as cylinder head gasket failure or piston cracking.

[0008] The turbocharger, or rather its compressor turbine, draws in air (usually from the environment) and compresses it to a desired boost pressure. This heats the air, raising it to an unacceptably high temperature. For example, at a desired boost pressure of approximately 2.5 bar and a normal ambient temperature of around 20 °C, the temperature would reach approximately 180 °C [one hundred and eighty degrees Celsius]. Therefore, the intake air must be cooled, for example, to 15 °C [fifteen degrees Celsius].

[0009] During full-load operation of an internal combustion engine, the exhaust gas often provides excessive compression power due to the operating range of the turbocharger. Current solutions involve bypassing the turbocharger's exhaust turbine and / or converting some of the torque generated in the turbocharger into usable electrical energy through recuperation.

[0010] Here, a different approach is used, in which the excess power during full-load operation, when the charge air temperatures become excessively high, is directly used to cool the charge air. In the first step, the charge air is compressed to an excessively high pressure and temperature. In the second step, this excess energy from the charge air is expanded and cooled using a Ranque-Hilsch vortex tube. This will be explained in more detail below.

[0011] It should be noted that a Ranque-Hilsch swirl tube contains no moving parts and is therefore very robust, safe, and requires little maintenance. The rest of the charge air system, according to the proposal presented here, is also simple in design and has a low overall mass.

[0012] In a Ranque-Hilsch vortex tube, a pressurized gas is split into two partial flows, which undergo (open) counterflow cooling, resulting in a heated partial flow and a cooled partial flow from the (single) compressed air supply. The pressurized gas (here, the charge air from the compressor turbine) is injected tangentially to a rotational axis into a vortex chamber of the Ranque-Hilsch vortex tube. The charge air is set into very rapid rotation around the rotational axis, reaching speeds of up to over 1,000,000 rpm (one million revolutions per minute). The vortex chamber is equipped with differently shaped axial air outlets (defined relative to the rotational axis): firstly, an inlet outlet for the cold charge air for a combustion chamber of an internal combustion engine, and secondly, a return outlet for the exhaust air heated during the process.In technical applications, it is generally possible to achieve temperature differences of +20 °C to -50 °C with a compressed air supply of 6 bar, whereby the majority of the airflow is heated. During operation of the device, a characteristic whistling sound is produced with a frequency of approximately 3 kHz and a volume of about 120 dB. Very high centripetal forces occur in the vortex chamber, but these alone cannot cause the observed separation into an outer warm and an inner cold stream. It is certain that the very loud whistling sound is necessary due to processes that are not yet fully understood, because as soon as it is dampened by coupled absorbing resonators, the temperature difference decreases to only a few Kelvin. Furthermore, a Ranque-Hilsch vortex tube exhibits a very low efficiency compared to conventional cooling methods.

[0013] The following explains in detail how this Ranque-Hilsch vortex tube can be used efficiently in the proposed charge air system.

[0014] The compressor turbine of a turbocharger, which is driven (for example, exclusively) by the exhaust gas of the associated internal combustion engine via an exhaust gas turbine of the turbocharger, draws in air (usually from the immediate surroundings) through an air inlet (preferably routed through an air filter). It should be noted that in certain operating conditions, a closed circuit may be formed in which no external air is required or can be drawn in. It should also be noted that in one embodiment, the compressor turbine is driven exclusively or additionally by an electric drive motor.

[0015] For optimal operation, it is proposed that the air be converted into charge air and pressurized by the compressor turbine to a pressure above a desired boost pressure in the intake chamber, for example, to 4 bar [four bar]. In addition, the charge air is heated more than conventionally, in the example given to, for example, 250 °C [two hundred and fifty degrees Celsius].

[0016] Downstream of the charge air flow, the compressor turbine is not directly connected to the Ranque-Hilsch vortex tube, but rather to an intercooler, as is typical in a design without a Ranque-Hilsch vortex tube. However, in this case (with the desired vortex cooling operation using the Ranque-Hilsch vortex tube), the intercooler does not cool the charge air to the desired temperature of the charge air in the intake chamber, but instead raises its temperature significantly. In the example mentioned above, the pressure downstream of the intercooler is 4 bar (cooling occurs approximately isobarically) and the temperature is 50 °C [fifty degrees Celsius].

[0017] This still-warm charge air is then introduced via the compressed air inlet of the Ranque-Hilsch vortex tube (tangential to its axis of rotation) for cooling and expansion. Ideally, a temperature of 15 °C and a boost pressure of 2.5 bar should be achieved in the intake air discharged through the inlet outlet for the combustion engine's intake chamber. As described above, for optimal efficiency, the significantly larger portion of the flow is that containing the heated air, for example, in a ratio of 3:1 [three to one] to the cooled portion.

[0018] However, the opposite is proposed here: the cooled partial flow, i.e., the inflow, is significantly larger than the heated partial flow, i.e., the exhaust air or return flow. For example, to achieve the temperature and boost pressure to be reached in the previously mentioned example, the ratio of return flow to inflow would be 1:3 [one to three]; in other words, 75% is discharged via the inflow outlet and 25% via the return flow outlet. In this example, a temperature of 120 °C and (necessarily) a pressure of 2.5 bar are generated. This ratio, with the resulting temperatures and pressures of the inflow and return flow, is achieved or controlled (usually regulated) by the return flow restrictor downstream of the return flow outlet.

[0019] In addition to achieving optimal temperature and boost pressure, and avoiding the use of water in the combustion chamber, the following is also achieved: - the excess kinetic energy of the exhaust gas is used in the Ranque-Hilsch vortex tube to cool the charge air and no recuperation is necessary at the turbocharger; - the operating point of the Ranque-Hilsch vortex tube required in this charge air system architecture reduces the volume of the characteristic whistling sound; and - The Ranque-Hilsch vortex tube is preferably only actively used (and produces the loud whistling sound) when the internal combustion engine is operated under high load, for example full load, where a high noise level is at least accepted, and sometimes even desired.

[0020] In an advantageous embodiment of the charge air path, it is further proposed that a return channel with a recooler be provided between the return flow outlet of the Ranque-Hilsch vortex tube and the compressor turbine for the purpose of returning the return flow.

[0021] It is further proposed that the return flow be reintroduced into the compressor turbine via a recirculation channel alongside the ambient air (e.g., from the immediate surroundings). This return flow contains contaminants, including blow-by gases and lubricating oil leakage, meaning it should not be released back into the environment untreated, nor would this comply with regulations in most countries. Therefore, instead of simply feeding the return flow into the exhaust stream via a catalyst, a repeated reintroduction to the compressor turbine is proposed.

[0022] As described above, this partial flow is heated, for example to 120 °C. It is proposed here that a recooler be provided in the return channel. Using the recooler, the return flow is cooled, for example, to approximately 20 °C, possibly more or less, in order to bring the intake (mixed) air up to a suitable temperature, for example 20 °C, before it enters the compressor turbine. Preferably, cooling in the recooler is also carried out (approximately) isobarically. Preferably, the return flow restrictor is located downstream of the recooler in the flow direction. A reduction of the pressure in the return flow to atmospheric pressure is preferably achieved by means of the return flow restrictor, or alternatively by a separate expansion nozzle.

[0023] The recooler has another advantage, namely that the (air) noise emission caused by the process in the Ranque-Hilsch vortex tube is further reduced, as well as that (as mentioned before) the temperature of the air drawn in by the compressor turbine can be adjusted to a desired (e.g. constant) temperature.

[0024] In one embodiment, the return channel is openly connected to an intake channel for the air drawn in from the environment by the compressor turbine, so that the mixing ratio between return flow and (fresh) air is passively adjusted.

[0025] In a further advantageous embodiment of the charge air system, it is proposed that a bypass channel with a bypass throttle valve is also provided. whereby, by means of the bypass channel, charge air can be directed behind the charge air cooler past the Ranque-Hilsch vortex tube into an intake chamber of an internal combustion engine.

[0026] It should be noted that the charge air system is only explained here with regard to the application described herein, and it is not excluded that further lines, sections and devices are provided permanently or switchably, which, for example, also allow a different operating mode of the charge air system.

[0027] As previously described, the optimal operating point is full-load operation of the internal combustion engine belonging to the charge air system (i.e., the engine being turbocharged). Outside of this range, sufficiently low pressures and temperatures occur in the charge air, or any deviations can be dissipated conventionally (using an intercooler).

[0028] It is proposed here that, for operation outside critical operating points in the area of ​​the intake chamber of the internal combustion engine and / or in the exhaust-driven turbocharger, the charge air is routed past the Ranque-Hilsch vortex tube via a bypass channel from the charge air cooler into the intake chamber of the associated internal combustion engine. A bypass throttle valve is provided to control the bypass channel, which, when fully open, directs the entire charge air volume flow through the bypass channel into the intake chamber, for example, solely due to the higher back pressure caused by the Ranque-Hilsch vortex tube or (optionally additionally) by means of a throttle valve (upstream and / or preferably exclusively downstream) of the Ranque-Hilsch vortex tube.

[0029] According to another aspect, a method for cooling charge air for an internal combustion engine by means of a charge air path is proposed according to an embodiment as described above, wherein the method comprises at least the following steps in the order mentioned: a. by means of the compressor turbine, compressing the charge air to over 3 bar; b. by means of the charge air cooler, pre-cooling the compressed charge air to between 80 °C and 30 °C; c. by means of the Ranque-Hilsch vortex tube, cooling the pre-cooled charge air to a target temperature of below 20 °C and expanding it to a target boost pressure of 3 bar or less, where the cooling of the charge air to a desired target temperature is controlled by adjusting the return flow from the Ranque-Hilsch vortex tube of the return throttle, where the flow volume of the return flow is smaller than that of the inflow.

[0030] The method proposed here is a preferred operating method for the charge air system in an embodiment according to the present description. It should be noted that the charge air system can be operated differently, and the method is also applicable to other (similar) charge air systems. Insofar as aspects of the method are already described in the previous description with regard to the charge air system, these are at least optionally included in the method proposed herein.

[0031] In step a., the charge air is compressed by a compressor turbine of the turbocharger. This increases the charge air pressure to over 3 bar. An optimal charge pressure is 4 bar, because this allows the Ranque-Hilsch vortex tube to operate optimally for a desired charge pressure (e.g., 2.5 bar) and charge temperature (e.g., 15 °C). For example, the air drawn in by the compressor turbine is heated to 250 °C.

[0032] In step b., the charge air is pre-cooled by means of the charge air cooler. The charge air is brought to a temperature between 80 °C and 30 °C. Charge air cooling is preferably carried out at approximately isobaric temperatures. An optimal temperature is 50 °C, because at this temperature the charge air after the charge air cooler is brought to a temperature level that results in an advantageous ratio of (low) return flow to (high) supply flow in the Ranque-Hilsch vortex tube.

[0033] In step c of the process, the pre-cooled charge air is further cooled using the Ranque-Hilsch vortex tube. The charge air is cooled to a target temperature of below 20 °C and expanded to a target boost pressure of 3 bar or less. The Ranque-Hilsch vortex tube is supplied via the compressed air inlet (preferably by controlled flow) such that the desired target temperature and boost pressure are achieved. In one embodiment, the inlet pressure and / or the inlet temperature of the charge air at the compressed air inlet of the Ranque-Hilsch vortex tube fluctuates. Alternatively or additionally, the desired target temperature and / or the desired boost pressure fluctuates within a predefined operating range.

[0034] An optimal temperature in step c is 15 °C and an optimal boost pressure of 2.5 bar, because at this boost pressure and temperature, the conditions are optimal for the combustion process in the combustion chamber and for a long service life of an internal combustion engine. The Ranque-Hilsch vortex tube is geometrically optimized for these (or other) desired values ​​and / or supplied with compressed air at the compressed air inlet.

[0035] The flow resistance at the return flow outlet of the Ranque-Hilsch vortex tube can be adjusted (i.e., controlled or regulated) by means of the return flow restrictor, whereby preferably the boost pressure depends solely on the pressure provided by the compressor turbine and the temperature can be changed (quasi-isobarically) by means of the return flow restrictor by changing the ratio of the flow volumes of the return flow to the inflow.

[0036] It should be noted that, unlike the conventional operation of a Ranque-Hilsch vortex tube, the flow volume of the return flow is (preferably considerably) lower than that of the supply flow. This also allows the return flow to be recycled to the compressor turbine without having to discharge an excess of heated exhaust air. In one embodiment, the flow volume of the return flow is always less than twice that of the supply flow, so that at such an operating point, no air is drawn in from the environment and there is no excess exhaust air. Alternatively, at another operating point, excess exhaust air is fed into the exhaust gas and preferably passed through a catalyst.

[0037] In a further advantageous embodiment of the method, it is proposed that, by means of a charge air path according to an embodiment as described above, the return flow from the return flow outlet of the Ranque-Hilsch vortex tube is reintroduced upstream of the compressor turbine via the return channel. wherein the return flow is cooled down to below 55 °C, preferably below 35 °C to ambient temperature or less, by means of the recooler.

[0038] By feeding the return flow from the Ranque-Hilsch vortex tube directly back into the compression stage, the (potentially contaminated) exhaust air from the cooling process is recaptured in the Ranque-Hilsch vortex tube and thus not released unused into the environment. Furthermore, the compressor turbine is supplied with adjustable or at least dampened fluctuations in the ambient air supply. Any contamination present in this configuration originates almost exclusively from the compressor turbine (primarily blow-by gases and lubricants) and therefore does not impair its operation.

[0039] Under optimal operating conditions, the return flow is cooled to 20 °C, which is, for example, an optimal ambient temperature. However, in some operating conditions, the ambient air is warmer or colder. Using the recooler in the return channel, a virtually any temperature can be set, so that the actual ambient temperature, together with the temperature of the cooled return flow, can be adjusted to an optimal temperature, for example, the often ideal 20 °C.In one embodiment, structural measures that influence the flow and / or a pressure in the return flow slightly above 1 bar (i.e., ambient pressure) ensure that the return flow is reliably drawn back into the compressor turbine and fed into the process, while only as much ambient air is drawn in as is additionally required, i.e., for example, with a 25% return flow share, 75% fresh air from the environment.

[0040] In a further advantageous embodiment of the method, it is proposed that the flow volume of the inflow to the internal combustion engine can be controlled by means of an inflow throttle valve.

[0041] To control an internal combustion engine, for example for desired acceleration or deceleration, different charge volumes in the intake chamber are necessary. This requires an inflow throttle valve, which in this case is located downstream of the Ranque-Hilsch vortex tube. In the case of a bypass channel, the inflow throttle valve is preferably also located between the bypass channel and the intake chamber. Preferably, the inflow throttle valve is controlled or regulated in conjunction with the return throttle valve, so that the desired temperatures and pressures can be generated in the Ranque-Hilsch vortex tube.

[0042] In one embodiment, the ratio of the inflow to the return flow is then changed, for example by means of the charge air cooler, a suitable supply temperature is set so that no undercooled or overheated air is introduced into the intake chamber.

[0043] In a further advantageous embodiment of the method, it is proposed that the method be started depending on at least one of the following conditions: - Ambient temperature; - Temperature of the charge air in the intake chamber of the internal combustion engine; - Speed ​​of the exhaust turbine; - Position of an accelerometer.

[0044] During operation, the ambient temperature is very high, and the heat would otherwise have to be dissipated via the charge air cooler. By initiating this process, this heat energy can be used more efficiently.

[0045] In normal operating conditions, the charge air temperature is too high, and the heat would otherwise have to be dissipated via the charge air cooler. By initiating this process, the available thermal energy in the Ranque-Hilsch vortex tube can be used more efficiently.

[0046] In operating conditions, the rotational speed of the exhaust gas turbine is very high (and also of the compressor turbine if the turbine shaft is rigid). This additional available energy is detected via this rotational speed, and the process is initiated, whereby this energy is converted into heat energy and then utilized in the Ranque-Hilsch vortex tube.

[0047] During operation, the future rotational speed of the exhaust turbine can be read by detecting and taking into account the position of an accelerometer (for example, implemented as a so-called accelerator pedal). This allows for a very early and rapid response in order to utilize the additional energy that will be available in the near future in the Ranque-Hilsch vortex tube.

[0048] In a further advantageous embodiment of the method, it is proposed that, for bypass operation using a charge air path according to an embodiment as described above, charge air is directed behind the charge air cooler past the Ranque-Hilsch vortex tube into the intake chamber of the internal combustion engine via the bypass channel. wherein preferably before or during a change from bypass operation to swirl cooling operation, an overpressure is generated in the intake chamber using the Ranque-Hilsch swirl tube to carry out step c. of the method.

[0049] The process is not energy-efficient in every operating condition, and a secondary route (the bypass channel) around the Ranque-Hilsch vortex tube is advantageous in these other operating conditions. This ensures a reliable supply of charge air to the intake chamber using simple means.

[0050] However, as soon as the compressor turbine experiences excess power compared to operating the charge air system without the Ranque-Hilsch vortex tube, a switch must be made. Because the Ranque-Hilsch vortex tube has a delayed response and a brief overpressure in the intake chamber is not critical, a method is proposed here in which the resulting overpressure due to the excess power of the compressor turbine is initially allowed, and then the system switches to the Ranque-Hilsch vortex tube. The resulting pressure drop due to the delayed response of the Ranque-Hilsch vortex tube then immediately reduces the overpressure in the intake chamber, and no interruption in traction is perceived by the users (e.g., vehicle occupants in a powered vehicle).

[0051] Alternatively or additionally, the bypass channel is throttled relatively slowly and the Ranque-Hilsch vortex tube is supplied with the desired operating pressure and volume flow accordingly slowly, thereby shortening the response time.

[0052] According to another aspect, an internal combustion engine for a motor vehicle is proposed, comprising at least the following components: - at least one combustion chamber; - a charge air system according to an embodiment as described above; - an intake chamber for at least one combustion chamber, which can be charged via the charge air system; - an exhaust channel for removing exhaust gas from at least one combustion chamber via the exhaust turbine of the turbocharger, preferably an exhaust gas cleaning device is connected downstream of the exhaust gas turbine.

[0053] The internal combustion engine is designed for direct or indirect propulsion (e.g., charging a traction battery). The engine is charged via a charge air system, with the turbocharger being oversized at maximum operation (full load) and generating excess power at the compressor turbine. This excess power is converted into a suitable, preferably optimal, charge air temperature in the intake chamber by means of the Ranque-Hilsch vortex tube. The turbocharger is supplied with exhaust gas from at least one (usually several) combustion chambers, specifically driving its exhaust turbine. Preferably, the turbocharger has no gearbox or recuperator, but rather a simple design, preferably with a single turbine shaft, so that the exhaust turbine and compressor turbine always operate at the same speed.

[0054] Preferably, an exhaust gas purification device, for example a two-way catalytic converter, exhaust gas filter and / or three-way catalytic converter, is provided. Preferably, little pressure and heat are extracted from the exhaust gas at the exhaust gas turbine before it enters the exhaust gas purification device, so that the exhaust gas purification device can be operated in an optimal (high) temperature range and without generating excessive back pressure at the combustion chamber or at the exhaust gas turbine with a non-negligible flow resistance.

[0055] According to another aspect, a motor vehicle is proposed comprising a transport cabin, a drive train with an internal combustion engine according to an embodiment as described above, and a drive axle with at least one drive wheel. wherein at least one drive wheel can be driven to propel the motor vehicle by means of a torque output from the drive train.

[0056] The motor vehicle is designed to transport at least one passenger and / or goods and therefore has at least one transport compartment (e.g., passenger compartment and / or cargo compartment). The motor vehicle is driven via at least one drive wheel by means of the torque from at least one drive engine (also referred to as a traction engine in this function). At least one of the drive engines is an internal combustion engine and is configured to deliver torque for propelling the motor vehicle. For example, an electric drive motor may also be used on a second (additional) drive axle of the motor vehicle, while the (fuel-burning) internal combustion engine serves as the primary drive for the motor vehicle.The internal combustion engine is equipped with a charge air system which achieves a high efficiency and is also simple (also in terms of manufacturing and maintenance) and has a comparatively low mass (for example compared to a recuperative system).

[0057] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, although it should be noted that the drawings are not dimensionally accurate and are not suitable for defining size relationships. It is illustrated in Fig. 1 in a schematic representation a charge air system with internal combustion engine, and Fig. 2. A schematic top view of a motor vehicle with an internal combustion engine.

[0058] In Fig. Figure 1 shows a schematic representation of a charge air system 1 with an internal combustion engine 2. The charge air system 1 is subjected to airflow in the indicated flow direction 3. The charge air system 1 begins with a compressor turbine 4 of a turbocharger 5, which is driven by an exhaust gas turbine 6. The charge air system 1 also includes an intercooler 7, which is located downstream of the compressor turbine 4. A Ranque-Hilsch vortex tube 8 is arranged after the intercooler 7. This vortex tube has a compressed air inlet 29, a swirl chamber 30, an inlet outlet 9, and a return outlet 10. The inlet outlet 9 is connected via an intake chamber 19 to a combustion chamber 12 of an internal combustion engine 2. The return outlet 10 is connected to a recirculation channel 15, which is (optionally) equipped with a recooler 16.A bypass channel 17 with a bypass throttle valve 18 is optionally provided in the charge air path 1, through which charge air behind the charge air cooler 7, past the Ranque-Hilsch vortex tube 8, and into the intake chamber 19 of the internal combustion engine 2. An inflow throttle valve 20 is designed to control the flow volume of the charge air into the intake chamber 19. The charge air, compressed by the compressor turbine 4 and pre-cooled by the charge air cooler 7, is introduced into the Ranque-Hilsch vortex tube 8 via the compressed air inlet 29, where it is split into two flows. This cools an inflow 11 and warms a return flow 13. Simultaneously, both flows are expanded. For example, a ratio of 1:3 (return flow 13 to inflow 11) is set. This is adjustable via the return flow throttle valve 14.The return flow 13 is cooled down to ambient temperature here (purely optionally) via the recooler 16 and mixed with the fresh air, which is drawn in from the environment 31 via the air inlet 32 ​​(usually via an air filter 33). For an explanation of adjustable temperatures and pressures, please refer to the preceding description.

[0059] The compressor turbine 4 is connected to an exhaust gas turbine 6 (e.g., torque-resistant), the exhaust gas turbine 6 being driven by exhaust gas 23 from the exhaust duct 22 of the internal combustion engine 2, thus depending on the operating state of the internal combustion engine 2. Here, the exhaust gas 23 is directed into an exhaust gas cleaning device 24 after flowing through the exhaust gas turbine 6. The charge air introduced into the intake chamber 19 is brought to a desired pressure (e.g., 2.5 bar) and a desired temperature (e.g., 15 °C), which also influences the exhaust gas temperature, preventing it from becoming too high, because the temperature in the combustion chamber 12 does not become too high during combustion.Excess drive energy at the exhaust turbine 6 is not only dissipated here, but used to cool the charge air, whereby the excessive boost pressure inevitably generated at the compressor turbine 4, together with an excessive temperature, does not have to be completely dissipated by the charge air cooler 7, but is instead converted in the Ranque-Hilsch vortex tube 8.

[0060] In Fig. Figure 2 shows a schematic top view of a motor vehicle 21 with an internal combustion engine 2 as a traction motor on the rear axle. The motor vehicle 21 also includes a passenger cabin 25, which is equipped for transporting passengers and / or goods. Propulsion of the motor vehicle 21 can be generated by means of a drive train 26 with a drive axle 27 and (here two) drive wheels 28. The drive train 26 includes an internal combustion engine 2, which is connected to the drive wheels 28 via a transmission and a differential 34 to transmit torque. The internal combustion engine 2 is connected to a charge air system 1 (as, for example, in Fig. (1 explained) equipped, which is shown here only schematically. Furthermore, an exhaust gas channel 22 is indicated, through which the exhaust gas 23 from the combustion chambers 12 of the internal combustion engine 2 is discharged via an exhaust gas turbine 6 of the turbocharger 5 of the charge air path 1.

[0061] With the charge air system proposed here, efficient full-load operation of an internal combustion engine can be achieved using simple means. Reference symbol list 1 Charge air line 2 Internal combustion engine 3 Flow direction 4 compressor turbine 5 turbochargers 6 Exhaust gas turbine 7 Intercoolers 8 Ranque-Hilsch vortex tube 9 Inflow outlet 10 Return flow outlet 11 Inflow 12 Combustion chamber 13 Return current 14 Return flow restrictor 15 Feedback channel 16 cooling units 17 Bypass channel 18 Bypass throttle valve 19 Intake chamber 20 Inflow throttle valve 21 Motor vehicle 22 Exhaust duct 23 Exhaust gas 24 Exhaust gas purification system 25 Transport cabin 26 Powertrain 27 Drive axis 28 Drive wheel 29 Compressed air inlet 30 vertebral chamber 31 Surroundings 32 Air inlet 33 Air filters 34 Differential

Claims

[1] Charge air system (1) for providing charge air to an internal combustion engine (2), comprising at least the following components in the order mentioned along the flow direction (3): - a compressor turbine (4) of a turbocharger (5); - an intercooler (7) for cooling compressed charge air of the compressor turbine (4); - a Ranque-Hilsch vortex tube (8) with an inlet outlet (9) and a return outlet (10), wherein, during operation, an inlet (11) cooled from the cooled charge air flows through the inlet outlet (9) for a combustion chamber (12) of an internal combustion engine (2), and a heated return flow (13) flows through the return outlet (10); and - a return flow restrictor (14) for the return flow (13) of the Ranque-Hilsch vortex tube (8). [2] Charge air section (1) according to claim 1, wherein a return channel (15) with a recooler (16) is further provided between the return outlet (10) of the Ranque-Hilsch vortex tube (8) and the compressor turbine (4) for returning the return flow (13). [3] Charge air path (1) according to claim 1 or claim 2, wherein a bypass channel (17) with a bypass throttle valve (18) is further provided, wherein charge air can be directed behind the charge air cooler (7) past the Ranque-Hilsch vortex tube (8) into an intake chamber (19) of an internal combustion engine (2) by means of the bypass channel (17). [4] Method for cooling charge air for an internal combustion engine (2) by means of a charge air section (1) according to one of the preceding claims, wherein the method comprises at least the following steps in the order mentioned: a. by means of the compressor turbine (4), compression of the charge air to over 3 bar; b. by means of the charge air cooler (7), pre-cooling the compressed charge air to between 80 °C and 30 °C; c. by means of the Ranque-Hilsch vortex tube (8), cooling the pre-cooled charge air to a target temperature of below 20 °C and expanding it to a target boost pressure of 3 bar or less, wherein the cooling of the charge air to a desired target temperature is controlled by adjusting the return flow (13) from the Ranque-Hilsch vortex tube (8) of the return throttle (14), where the flow volume of the return flow (13) is smaller than that of the inflow (11). [5] Method according to claim 4, wherein by means of a charge air section (1) according to claim 2 the return flow (13) from the return flow outlet (10) of the Ranque-Hilsch vortex tube (8) is reintroduced upstream of the compressor turbine (4) via the return channel (15), wherein the return flow (13) is cooled down to below 55 °C, preferably below 35 °C to ambient temperature or less, by means of the recooler (16). [6] Method according to claim 4 or claim 5, wherein the flow volume of the inflow (11) to the internal combustion engine (2) is controllable by means of an inflow throttle valve (20). [7] Method according to any one of claims 4 to 6, wherein the method is started depending on at least one of the following conditions: - Ambient temperature; - Temperature of the charge air in the intake chamber (19) of the internal combustion engine (2); - Speed ​​of the exhaust turbine (6); - Position of an accelerometer. [8] Method according to any one of claims 4 to 7, wherein for bypass operation by means of a charge air path (1) according to claim 3, charge air is directed behind the charge air cooler (7) past the Ranque-Hilsch vortex tube (8) into the intake chamber (19) of the internal combustion engine (2) by means of the bypass channel (17), wherein preferably before or during a change from bypass operation to vortex cooling operation by means of the Ranque-Hilsch vortex tube (8) for carrying out step c. of the method, an overpressure is generated in the intake chamber (19). [9] Internal combustion engine (2) for a motor vehicle (21), comprising at least the following components: - at least one combustion chamber (12); - a charge air path (1) according to any one of claims 1 to 3; - an intake chamber (19) for which at least one combustion chamber (12) can be charged via the charge air path (1); - an exhaust gas channel (22) for removing exhaust gas (23) from the at least one combustion chamber (12) via the exhaust gas turbine (6) of the turbocharger (5), wherein preferably an exhaust gas purification device (24) is connected downstream of the exhaust gas turbine (6). [10] motor vehicle (21), comprising a transport cabin (25), a drive train (26) with an internal combustion engine (2) according to claim 9 and a drive axle (27) with at least one drive wheel (28), wherein at least one drive wheel (28) can be driven to propel the motor vehicle (21) by means of a torque output by the drive train (26).

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