Method and device for the flexible adaptation and use of waste heat from vehicle drives

Abstract

Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) with turbocharging (31tt / 31tv) and charge gas cooling with a charge gas cooler (31k), with low-pressure exhaust gas recirculation with a first EGR control valve (14) and with a low-pressure EGR branch (11, 11lpegr), which temporarily mixes exhaust gas with the fresh air from a fresh air path (10f) in a main exhaust gas stream (10ft) via the low-pressure EGR branch (11, 11lpegr) upstream of the charge gas cooler (31k) while partially closing a second EGR control valve (31dk), in particular an exhaust gas throttle valve (31dk), and with a coolant pump (7 and / or 2), which conveys the coolant of an engine cooling circuit to a cabin heater heat exchanger (4) and finally back to the internal combustion engine (1), characterized in that the fuel consumption of the internal combustion engine (1) in case of increased waste heat demand, especially in case of high cabin heating demand,by means of an engine control unit (20) temporarily artificially increased by the fact that the first EGR control valve (14) closes and the second EGR control valve (31dk) throttles the main exhaust gas flow towards the maximum permissible values ​​of the residual gas remaining in the combustion chamber and / or the exhaust back pressure.

Description

[0001] The invention is a supplementary application to the invention described under DE 10 2009 042 745 A1. It relates to vehicles with vehicle heating by utilizing the waste heat of the vehicle drive or its components, in which the waste heat available for cabin heating purposes is to be increased or used more efficiently and / or in which an energy source other than the drive is required for cabin heating purposes.

[0002] In a first step, the invention, like DE 10 2009 042 745 A1, relates to a method and a device for operating a cooling and heating circuit for motor vehicles with a coolant-cooled internal combustion engine with charging and charge air cooling, in particular with turbocharging, whose coolant is conveyed by a coolant pump to the heating heat exchanger for the cabin and finally back to the internal combustion engine, with adjusting devices influenced by the engine control for heating power-oriented variation of the combustion process within the internal combustion engine.

[0003] In addition to measures to simultaneously meet the specifications regarding cabin heating performance, pollutant emissions and fuel consumption, the continuation of DE 10 2009 042 745 A1 also focuses on measures that make it possible to deliver the required cabin heating performance with relatively low additional fuel consumption and / or to replace expensive auxiliary heaters, in particular expensive PTC auxiliary heaters or fuel-operated auxiliary heaters.

[0004] The further development of the invention focuses primarily on a method and a device for operating a cooling and heating circuit for motor vehicles with a turbocharged internal combustion engine with charge air cooling and exhaust gas recirculation (EGR) with a first EGR control valve in an EGR branch, which, with partial / complete closing of a second EGR control valve in the main exhaust gas stream, temporarily mixes exhaust gas with the combustion fresh air via an EGR path. The internal combustion engine of the supplementary application also has a cooling and heating circuit and is designed in its basic configuration to deliver optimized values ​​for exhaust emissions and fuel consumption in the legally mandated tests conducted with the heating and air conditioning systems switched off.In particular, the further development of the invention relates primarily to such an internal combustion engine with a low-pressure EGR design, in which exhaust gas is temporarily recirculated to the combustion fresh air via a low-pressure EGR path upstream of the charge gas cooler 31k, which is taken downstream of the turbine 31tt of a turbocharger and upstream of a second EGR control valve 31dk arranged in the main exhaust gas stream.

[0005] In particular, the invention also relates to the cost-efficient generation of electrical energy from the waste heat of the vehicle drive system, especially from combustion exhaust gas, by means of thermoelectric generators (TEGs) and to the improvement of cabin heating performance.

[0006] In particular, the application potential extends to any internal combustion engine with exhaust gas recirculation cooler with TEG and even to any vehicle drive systems with coolant-operated cabin heating heat exchanger and TEG.

[0007] It is well known that exhaust emissions from modern engines can be reduced through external exhaust gas recirculation. Separate EGR circuits with their own EGR control valve and water-cooled EGR cooler are now standard in many passenger car diesel engines.

[0008] Various methods for maximizing the amount of recirculated exhaust gas and minimizing the temperature of the recirculated exhaust gas, including the fresh gas temperature, are also known and are considered a promising means of reducing pollutant emissions.

[0009] In particular, already published future low-pressure EGR systems promise further potential for reducing the temperature of the charge air including EGR and thus for reducing pollutant emissions.

[0010] It is also known that modern passenger cars with highly efficient diesel engines, particularly in Central European latitudes, have auxiliary heating components for winter cabin heating. Water-based auxiliary heating using fuel-operated auxiliary heaters derived from parking heaters, or electrical heating of the coolant, or direct electrical heating of the cabin air using the familiar PTC auxiliary heaters, are the standard solutions on the market.

[0011] It is also generally known that most car manufacturers have conducted extensive in-house investigations to increase the waste heat from direct injection diesel engines for cabin heating purposes by adjusting the internal combustion process, with the well-known result that the aforementioned auxiliary heating components could not be eliminated to this day.

[0012] Relevant patent specifications from various vehicle manufacturers, both older and more recent, document these attempts.

[0013] In particular, today's diesel cars, which at least in Germany and especially in all cold European countries are still equipped with PTC auxiliary heaters or other external auxiliary heaters, or at least offer such as an equipment option, demonstrate the failure of all previous attempts to replace the PTC auxiliary heater, considered the most cost-effective solution, in vehicles with highly efficient / low-consumption diesel engines solely by means of engine control measures.

[0014] In general, many experts currently assume that in the future, due to the increasing fuel efficiency of future engines, even more powerful PTC auxiliary heaters than are common today will be required.

[0015] Whether this is ultimately due to the lack of effectiveness of the previous heating-power-oriented approaches on the part of the engine control, or to the strong increase in fuel consumption of known measures, which typically suggest a shift of combustion towards a later point after a short engine warm-up, is a matter of debate.

[0016] In patent applications DE 102 49 541 A1 and DE 10 2009 042 745 A1, the patent applicant has demonstrated ways in which engine control measures can be used effectively to increase cabin heating performance, even to the point of eliminating the need for a PTC auxiliary heater. Particularly in conjunction with adjustments to the cooling and heating circuits, some exceptionally fuel-efficient methods are shown.

[0017] A certain weakness here, at least in part, is the effort required to modify the cooling and heating circuits, as well as the need to use a special heater core and / or deactivate the charge air cooler. Furthermore, as engines become increasingly fuel-efficient, the heating power deficit grows. Therefore, supporting cabin heating through heating-power-oriented engine control measures remains a viable option.

[0018] However, considerable resistance from experts to cabin heating output-oriented engine control measures, e.g., as described in DE 102 49 541 A1 and DE 10 2009 042 745 A1, remains to this day. The same applies to other cabin heating output-oriented proposals in the patent applications of various OEMs.

[0019] Besides negative experiences from tests showing a lack of effectiveness regarding cabin heating performance increase, the enormous increase in fuel consumption per gain in heating performance is a very significant argument against any engine control measures for cabin heating purposes.

[0020] In many cases, additional negative expectations / experiences regarding durability, condensation and icing, sooting of components, running characteristics or noise emission, smoke behavior with regard to soot and / or white smoke including odor behavior, as well as increased oil dilution, are the arguments that, according to the current state of knowledge, generally lead the experts not to even consider heating-performance-oriented engine control measures.

[0021] Patent application DE 10 2009 042 745 A1 demonstrates ways in which many existing reservations regarding heating-performance-oriented engine control measures can be overcome and describes a range of application-specific individual solutions. Depending on customer-specific reservations or depending on the installation space, cost, or fuel consumption target values, various solutions are presented to save the costs of the diesel-typical PTC auxiliary heater.

[0022] A certain disadvantage of the solutions proposed there lies, firstly, in the considerable application effort for the respective engine family, and secondly, in the increased fuel consumption and, in some cases, the component costs. Especially when transitioning to low-pressure EGR systems, additional concerns arise, particularly regarding condensation and droplet formation.

[0023] Furthermore, it is known to generate electrical energy from the hot exhaust gas of combustion engines using thermoelectric generators (TEGs). The publication "Liebl, J. et al.: The BMW thermoelectric generator makes waste heat usable. (In: MTZ 04 / 2009, pp. 272-281)" describes such a system in the form of a TEG in an exhaust gas heat exchanger arrangement, where the exhaust gas in the main exhaust stream serves as the heat source and the engine cooling coolant as the heat sink for the TEG. The arrangement of the TEG in the main exhaust stream under the vehicle shown there is relatively complex in terms of installation space and cost, as an exhaust-side bypass system is provided for thermal protection.

[0024] To avoid this effort, alternative solutions propose designing the EGR cooler branch or the EGR cooler itself as a TEG system in diesel engines. Such a system is briefly outlined in the publication "Up to 1000 W possible via thermoelectrics. (In: ATZ 12 / 2009, p. 901)."

[0025] This topic is also addressed in the publication "Eder, A., Neugebauer, St.: Nothing is lost: Thermal management as a building block of BMW's Efficient Dynamics strategy. (In: Conference on Thermal Management of Motor Vehicles VII, 2010, pp. 360-377. - ISSN 978-3-8169-3024-2)". Integrating the TEG into the EGR cooler significantly reduces costs, particularly since no additional valves are required on the exhaust side.

[0026] The exhaust gas extraction point for EGR-TEGs has so far been deliberately chosen to be in front of the turbine in order to provide the highest possible temperature potential for the TEG.

[0027] A significant disadvantage of the EGR-TEG is that it can only achieve a fraction of the maximum possible output of a TEG in the main exhaust stream. This is because, despite high exhaust gas temperatures when exhaust gas is extracted upstream of the turbine, the exhaust gas mass flow in the EGR branch is typically considerably lower than in the main exhaust stream. Furthermore, the EGR is often inactive or only minimally active.

[0028] For these reasons in particular, many experts favor the TEG described above in the main exhaust stream below the vehicle with an exhaust-side bypass solution – in the long term.

[0029] In contrast, the object of the present invention is to control internal combustion engines in motor vehicles, utilizing the potential and components that these engines already possess due to further development towards improved fuel consumption and / or pollutant emissions in the statutory exhaust gas test (i.e., with cabin heating and air conditioning switched off), in the event of cabin heating performance deficits and / or during normal operation on the road, by means of the engine control unit and, if necessary, additional devices, in such a way that improved cabin heating performance and / or reduced fuel consumption is achieved with minimal additional components and / or low application effort and / or low application risk, and in particular that electric PTC auxiliary heaters can be omitted and / or that electric PTC auxiliary heaters with reduced power and reduced system costs are sufficient.In particular, the findings from DE 10 2009 042 745 A1 regarding its task and its solution should be taken into account, and their applicability should be extended to future engine designs.

[0030] This problem is solved by the method according to claim 1.

[0031] The other independent claims also solve this problem on their own and in conjunction with the assigned claims.

[0032] In many respects, the inventive method also directly solves the problem described in DE 10 2009 042 745 A1. This applies in particular to the extension of the potential adjustment range for heating-power-oriented motor control measures.

[0033] A crucial means for the inventive method of cost-effective improvement of the vehicle outside of the statutory emissions test is the exhaust flap 31dk in the main exhaust stream 10ft, which can be controlled by the engine control unit.

[0034] An important aspect of the invention is that in some applications, particularly in future low-pressure EGR systems, this is already installed or planned for the legally mandated exhaust gas test, or that the low-pressure EGR in conjunction with the additional potentials according to the invention ultimately emerges as the superior system.

[0035] Without being limited to this, the following description of the invention initially focuses on engines with low-pressure EGR systems.

[0036] The transition from today's standard high-pressure EGR systems to a low-pressure EGR system often requires an exhaust-side throttle valve 31dk, depending on the EGR concept. In other words, the throttle valve 31dk, e.g., according to Fig. 1 or Fig. 3 is advantageous or necessary purely for emission reasons.

[0037] The resulting synergistic degrees of freedom with regard to the inventive control of the EGR valve 14 and the exhaust gas throttle valve 31dk for cabin heating purposes are therefore cost-neutral for certain variants of low-pressure EGR systems.

[0038] By continuing / adapting the findings from DE 10 2009 042 745 A1, it is thus possible – in a highly simplified view – with the EGR branch open, among other things, to make the exhaust gas flow rate through the turbine 31tt of the turbocharger and the gas flow rate through the turbo compressor 31tv almost as high as with the inventive procedure according to DE 10 2009 042 745 A1, despite activated exhaust gas recirculation.

[0039] In contrast to DE 10 2009 042 745 A1, the exhaust mass flow in the main exhaust branch 31ft can now be significantly reduced by means of the throttle valve 31dk in the exhaust system. This ultimately results, among other things, in a relatively high boost pressure with a slightly increased exhaust back pressure and relatively low exhaust heat losses in the main exhaust branch 10ft.

[0040] Even with external EGR deactivated, i.e. with the first EGR control valve closed, according to the invention a boost pressure that is as high as possible is preferably set in case of a heating power deficit, while simultaneously throttling the main exhaust gas flow with the second EGR control valve 31dk in the main exhaust gas stream 10ft.

[0041] This approach, in conjunction with the typical diesel-type charge exchange valve timing of the intake and exhaust valves, results in a certain increase in the residual gas volume. Furthermore, at typical part-load operating points with a heating power deficit, it still delivers a relatively high boost pressure, given that the fresh air pressure applied to the turbocharger is almost at ambient pressure.

[0042] The exhaust-side throttling via the second EGR control valve 31dk, with the first EGR valve 14 closed, will generally only result in a moderate reduction of the fresh air and exhaust gas mass flow, especially when the valve overlap of the charge exchange valves is very small or even completely absent. This is primarily due to the fact that, despite the exhaust-side throttling, the turbocharger is supplied with a sufficient quantity of exhaust gas from the individual cylinders, and the exhaust-side throttling primarily only increases the charge exchange work during exhaust gas expulsion.

[0043] Nevertheless, exhaust-side throttling is useful within certain limits for limiting exhaust heat losses. This applies not only to higher internal EGR but also to a faster transition to external EGR activation.

[0044] In particular, the increased fuel consumption induced by exhaust-side throttling, in conjunction with higher internal EGR and higher charge temperatures, facilitates a design of injection times and / or ignition that increases fuel consumption and cabin heating performance.

[0045] The existing throttle valve 31dk can be used, especially when the EGR branch is closed, to significantly increase charge exchange losses – either on its own or in conjunction with injection times adjusted in favor of heating – in order to reach a minimum component temperature of the engine and coolant as quickly as possible.

[0046] This in turn helps, especially with potential concerns regarding component contamination, to activate the EGR branch and the EGR cooler relatively early during warm-up, as well as to achieve the operating mode described above with a high EGR rate and high gas flow through the turbine and compressor and at the highest possible boost pressure.

[0047] As already in DE 10 2009 042 745 A1, despite the throttling by the partially or completely closed valve 31dk, it is also possible and particularly advantageous here in many operating points with cabin heating performance deficit if the effective boost pressure of the fresh air including the recirculated exhaust gas applied to the combustion chamber during charge exchange is adjusted towards the maximum possible value, in particular to a value that is at least 25% above the boost pressure during normal operation and preferably at least 1.5 bar when the vehicle is stationary.

[0048] A relatively high charge density and charge temperature at the injection time allows for a heating-performance-oriented shift in injection timing, particularly without risk. It is especially advantageous here if, compared to normal operation without adjusting the engine control unit 20 towards increased cabin heating output, this is achieved in conjunction with a shift in the fuel injection timing such that the first injection(s) before top dead center (TDC) is / are advanced by at least 5° crank angle (CA) and / or the last injection(s) after TDC are retarded by at least 5° CA.

[0049] In comparison to DE 10 2009 042 745 A1, the further development according to the invention is characterized in particular by the fact that the fresh air mass flow and the exhaust gas mass flow that escapes to the environment are smaller on average over time during operation with a heating power deficit.

[0050] In DE 10 2009 042 745 A1 and in the further development according to the invention, it is particularly advantageous during the warm-up phase to maximize cabin heating performance if the effective fresh air mass flow m L,eff The combustion to reduce a cabin heating performance deficit at engine speeds below 1500 rpm is at least temporarily less than 50% of a value with the displacement V H , the engine speed n and the ambient air density raw L,Umgebung according to the equation m L,ref = ((n / 2) / 60) * V h * raw L,Umgebung ) formed reference fresh air mass flow M L,ref .

[0051] Typical cabin heating performance tests are often conducted at approximately 50 km / h and engine speeds between 1200 and 1600 rpm. For such a test, with an engine speed of, for example, 1500 rpm, this calculation results in a reference fresh air mass flow of m³, assuming an air density of 1.2 kg / m³ and an engine displacement of 2.0 l. L,ref= ((1500 / 2) / 60) * 2.0 / 1000 * 1.2) = 0.030 kg / s and thus a target value for the effective fresh air mass flow of m L,eff < 0.015 kg / s.

[0052] For a turbocharged direct-injection diesel engine, these are values ​​that are completely unprecedented. However, as measurements show, such operation is not only possible, but often also highly advantageous in terms of effective cabin heating with moderate fuel consumption increases. In particular, it is even possible in some cases to operate at the aforementioned operating point with effective fresh air mass flows of only 0.010–0.012 kg / s or less, as soon as the EGR is activated or after the first 3–5 minutes of warm-up at, for example, a starting temperature of -20°C have passed. These figures are primarily due to the particularly good efficiency of the turbocharger in low-pressure EGR configurations, which, for example, are analogous to... Fig. 1 or Fig. 3 are set up.

[0053] Pollutant emissions, including soot formation, are also surprisingly low, particularly when using the associated claims.

[0054] In this respect, the increased charging temperature and the increased charging density or at least the increased charging pressure are particularly helpful during operation according to the invention with a heating power deficit.

[0055] In addition, depending on the hardware, it is possible to switch relatively quickly to the particularly efficient operating mode with high EGR rates, and then, despite partial or complete closure of the throttle valve 31dk and despite a high EGR mass flow, a comparatively high charge density is present in the engine and at the same time a relatively high oxygen content of the charge gas.

[0056] In contrast to the basic design of DE 10 2009 042 745 A1, in the further development according to the invention it is possible, and advantageous for maximizing the cabin heating effect, to set a reduced fresh air mass flow – within the limits of what is possible for the engine – by means of the throttle valve 31dk, even in the very early warm-up phase, in particular already in the time window of 1-5 or even 1-2 minutes: On the one hand, to increase the charge exchange losses and at the same time limit the exhaust heat losses to the environment, and on the other hand, to reach the operating mode with high EGR as quickly as possible.

[0057] In particular, it is advantageous to increase the internal and / or external EGR, achieved by partially or completely closing the exhaust gas throttle valve 31dk to improve cabin heating performance, to such an extent that combustion is slowed down. This—similar to retarding the last injection—also shifts the combustion towards a later point. Even when maintaining the injection times that were originally set to be nearly optimal for fuel consumption, this shift towards a later point results in additional fuel consumption, which is superimposed on the increased consumption from the higher charge exchange work and is generally very welcome when cabin heating performance is lacking.

[0058] Especially when the DPF is appropriately integrated with an oxidation catalyst, a certain amount of additional soot and HC upstream of the oxidation catalyst or the DPF can even be temporarily accepted.

[0059] Particularly when this procedure is limited to extremely cold ambient temperatures below, for example, -10°C, and when using an almost emission-optimal EGR rate at higher ambient temperatures, the deliberately induced increase in fuel consumption is usually negligible on average over the year.

[0060] A number of further details will be explained later using examples from Fig. 1-6 discussed in more detail, without being limited to them.

[0061] In a first, particularly simple variant, the inventive method provides that the fuel consumption of the internal combustion engine is temporarily artificially increased by the engine control 20 in the event of increased waste heat demand, in particular in the event of high cabin heating demand, by closing the first EGR control valve 14 and by throttling the main exhaust gas flow in the direction of the maximum permissible values ​​of the residual gas remaining in the combustion chamber and / or the exhaust back pressure by the second EGR control valve 31dk.

[0062] In particular, only components are used that are required anyway due to the use of a low-pressure EGR system to meet the legal emissions test requirements, i.e., without extracting cabin heating power and also without the cabin heating power enhancement measures according to the invention. In other words, the inventive method for improving cabin heating is cost-neutral with regard to the components used.

[0063] With moderate throttle reduction, fuel consumption initially increases only relatively slightly. Besides the energy input into the coolant due to the increased fuel consumption, this approach increases the internal EGR (exhaust gas recirculation) and the amount of residual gas remaining in the engine, while simultaneously reducing the combustion air mass flow. Both of these factors increase the amount of engine-side waste heat transferred to the coolant. At the same time, the exhaust pressure in the exhaust manifold and in the combustion chambers of the individual cylinders increases, which also promotes heat transfer to the coolant.

[0064] Ultimately, this reduces the combustion fresh air mass flow 10f and, similarly, the exhaust gas mass flow 10ft ultimately exiting into the environment. Therefore, despite increased exhaust gas temperatures, the exhaust losses in the exhaust gas stream 10ft are sometimes even lower than without the increased fuel consumption due to exhaust gas throttling, especially in engines that exhibit high internal EGR at increased exhaust back pressure or can adjust it using variable valve timing. This makes this approach particularly attractive compared to the method described in DE 10 2009 042 745.7, which, in the phase without EGR, preferentially operates with high boost pressures and particularly high fresh air mass flows, but also induces higher exhaust heat losses, associated with certain disadvantages in fuel consumption. Therefore, it is especially important in this case to activate exhaust gas recirculation as early as possible, which is not always feasible.

[0065] In particular, depending on engine load and cabin heating requirements, the exhaust throttle valve 31dk can be adjusted to a greater or lesser degree of throttling, thus increasing or decreasing the cabin heating output. The existing measurement of the combustion fresh air mass flow by the engine control unit ensures that, despite the throttling, sufficient combustion air or excess air is available for safe and emission-free combustion.

[0066] In contrast to the current practice of temporarily throttling the fresh air mass flow during diesel particulate filter regeneration, using intake-side or charge gas-side throttling – e.g., with the throttle valve 31sdk in Fig. With valve 14 closed and valve 1 open simultaneously, this method according to the invention is characterized by a higher residual gas quantity in the combustion chamber, resulting in increased heat transfer to the combustion chamber walls and the coolant. This is beneficial for cabin heating and expands the adjustment range for heating-performance-oriented engine control measures by shifting the injection timing "earlier before top dead center" and / or "later after top dead center." This is due, firstly, to the higher gas temperatures at the injection time, and secondly, to the lower risk of wall wetting and oil dilution given the higher gas temperatures and pressures or gas density. The higher combustion chamber wall temperatures also promote the re-evaporation of fuel from the oil.

[0067] While the pressure in the combustion chamber in the injection / ignition area is not as high as with maximum boost pressure, e.g., according to some proposals in DE 10 2009 042 745 A1 without an exhaust throttle valve 31dk, the increased internal temperatures and pressure in the combustion chamber allow, in many applications, for a shift in the fuel injection timing (or timing) compared to normal operation without adjusting the engine control unit towards increased cabin heating performance. Specifically, the first injection (or injections) before top dead center (TDC) is advanced by at least 5° crank angle (CA) and / or the last injection (or injections) after TDC is retarded by at least 5° CA. This option enables a further increase in cabin heating performance.

[0068] Such a procedure is still relatively fuel-efficient, especially without a device 31b or 31sv for deactivating the charge gas cooling 31k. Nevertheless, it is generally more advantageous for fuel consumption and pollutant emissions not to forgo either the activation / maximization of the EGR or the device 31b or 31sv.

[0069] With regard to the regeneration of the particulate filter, the throttling according to the invention with the exhaust-side throttle valve 31dk provides a somewhat better starting point for cabin heating purposes, since the exhaust gas temperatures are higher than in normal operation. Against this background, this procedure can also be used advantageously without a cabin heating performance deficit to preheat the diesel particulate filter with oxidation catalyst 31dpf until the catalyst has reached a sufficient temperature to initiate the additional fuel injection for regeneration. This applies particularly in winter, where the additional heat introduced into the coolant generally does not pose a risk of overheating.In comparison to the currently common intake-side throttling of the combustion fresh air mass flow, this approach offers in particular more scope to support the preheating of the exhaust system by adjusting the injection towards a later timing and / or to reduce oil dilution with fuel.

[0070] When initiating the additional fuel injection for the regeneration of the DPF or other exhaust aftertreatment systems, it is usually advantageous, for reasons of fuel consumption and to avoid thermal overload, to deactivate the EGR with valve 14 and, if necessary, to fully open the exhaust-side throttle valve 31dk and switch to throttling the fresh air mass flow with flap 31sdk.

[0071] In this context, it is particularly advantageous for diesel engines with low-pressure exhaust gas recirculation that the engine control unit 20 deactivates the external exhaust gas recirculation, in particular by closing an EGR valve 14, and • in a first operating mode deviating from normal operation, with settings for regenerating a diesel particulate filter 31dpf or another exhaust aftertreatment component, a throttling of the combustion fresh air mass flow is carried out with an intake-side or charge-gas-side throttle valve 31sdk, so that the charge density in the combustion chamber and in the exhaust stream is reduced and • that the engine control, in a second operating mode deviating from normal operation, with settings for temporary cabin heating performance increase, performs an exhaust-side throttling of the combustion fresh air mass flow with a throttle valve 31dk, through which the entire main exhaust flow leaving the exhaust system towards the environment flows 10ft, so that the charge density in the combustion chamber and in the exhaust system is increased and the cabin heating effect is improved.

[0072] Furthermore, it is particularly advantageous if, to initiate / prepare the regeneration of the exhaust system, the exhaust-side throttle 31dk is also used initially, and only when the additional injection is initiated is the intake-side throttle 31sdk used.

[0073] The use of the exhaust-side throttle 31dk, which is already present in many low-pressure EGR systems, to improve cabin heating is very attractive in itself, since, apart from some software or application effort, no costs are usually incurred. If necessary, it also requires little additional effort to design the throttle 31dk slightly towards a higher maximum throttling effect or pressure resistance. Furthermore, the resulting increased residual gas volume or internal EGR, in contrast to external EGR, results in less surface heat loss to the environment and can be used without concerns regarding condensate formation or sooting in the EGR cooler 3 and / or the entire EGR system, including the EGR valve 14.

[0074] Nevertheless, for fuel consumption reasons, it is advantageous in many applications to drive with reduced throttling of flap 31dk as soon as possible and then to keep the fresh air mass flow 10f or the exhaust gas mass flow 10ft as small as possible by opening the EGR valve 14 to improve the cabin heating effect.

[0075] At the latest when the reduction of the fresh air mass flow alone, in conjunction with a high EGR rate, ensures sufficient cabin heating performance, this generally leads to better fuel consumption than exhaust-side throttling with flap 31dk without opening the EGR valve 14.

[0076] This applies particularly to an increased degree if the EGR cooler 3 is arranged in front of the heater heat exchanger 4 and, through a corresponding design of the heater coolant flow rates and the heater heat exchanger 4, is optimized for high, i.e., almost saturated, heat transfer with already moderate coolant flow rates, the waste heat transferred to the coolant at the EGR cooler is increasingly focused on the vehicle cabin.

[0077] As a rule, further advantages arise when the inventive method is additionally supported by further measures to increase heating performance in accordance with patent application DE 10 2009 042 745.7. In particular, this often results in advantages with regard to the increased fuel consumption required for the heating performance increase and the potential for soiling, deposit build-up, and condensate precipitation.

[0078] In particular, it is helpful if the measures for increasing heating output known from DE 10 2009 042 745 A1 are used temporarily. • that a reduction in coolant flow rate through the internal combustion engine occurs in the direction of the limit values ​​permissible for safe engine operation and / or particularly preferred for heating performance and / or • an electric intake air heater and / or • a charge air cooler deactivation and / or 1. if a division into separate combustion before and after top dead center results in an increase in the combustion chamber wall temperature and the compression temperature of the fuel gas at the start of combustion relative to the corresponding crankshaft position in normal operation without cabin heating-oriented fuel consumption increase.

[0079] These improvements can be combined to either maximize cabin heating efficiency or minimize increased fuel consumption. More detailed information is described in detail in DE 10 2009 042 745 A1 and can be easily adapted to specific applications in conjunction with the present application text.

[0080] Before activating the external EGR branch 11lpegr – which is generally desirable sooner or later, at least temporarily, in almost all vehicle applications for reasons of fuel consumption and emissions – the throttling of the exhaust gas mass flow according to the invention with the flap 31dk provides faster heating of the coolant and, in particular, of the water-cooled EGR cooler 3. A minimum coolant temperature in the EGR cooler is especially important if it is to be reliably prevented that water condenses from the recirculated exhaust gas and potentially damages the compressor turbine 31tv through droplet impact, or that the condensate forms a corrosive mixture together with the components of the exhaust gas.

[0081] To reliably prevent condensation in the mixed gas and the fresh gas, it is particularly advantageous to use a model for calculating the relative humidity of the recirculated exhaust gas and the combustion fresh air, and to limit the amount of recirculated exhaust gas so that condensation is largely prevented.

[0082] In this context, the inventive approaches of DE 10 2009 042 745 A1 and the present application also provide elegant possibilities to ensure preheating of the components involved before activating the external exhaust gas recirculation and still to enable a sufficient increase in cabin heating performance.

[0083] Maximizing the fresh air mass flow and boost pressure, and thus also the charging temperature, as well as deactivating the charge air cooler 31 k, preheating the EGR cooler 3 on the coolant side, and increasing the exhaust gas temperatures available at the time of EGR activation by means of the heating-power-oriented engine control measures and, if necessary, exhaust gas throttling with the flap 31dk, all help to reliably control a potential condensation problem.

[0084] This allows for a relatively early transition to addressing the cabin heating performance deficit via a high external EGR rate with a moderate adjustment of the injection parameters and / or a moderate throttling at flap 31dk, thus limiting or even eliminating the increased fuel consumption for cabin heating purposes.

[0085] This applies in general, but especially when the EGR cooler 3 is arranged in front of a high-performance heating heat exchanger 4 and when, compared to today's standard production models, small to medium coolant flow rates are used, so that a significant temperature increase is achieved at the heating supply line at the EGR cooler.

[0086] As with DE 10 2009 042 745 A1, it is – with certain limitations due to the generally somewhat lower boost pressures – very advantageous to perform multiple fuel injections with first and second injections, so that two separate combustion processes are generated that are largely, in particular to more than 90%, complete. The first injection(s) are particularly preferably advanced such that the combustion of the fuel introduced for the first combustion is largely completed before top dead center of the compression stroke, and the second injection(s) are advanced such that the second combustion begins after top dead center of the compression stroke.

[0087] To limit peak pressures and pressure gradients or noise emissions, it is particularly advantageous that the amount of fuel in the first combustion completed before TDC is approximately as large as that in the second combustion beginning after TDC, and in particular that a first main injection takes place before TDC with attached pre-injection(s) and a second main injection takes place after TDC with attached pre-injection(s).

[0088] The preceding explanations make it clear that, for reasons of fuel consumption, but also partly for other reasons such as drivability, soiling, sooting, condensation, etc., it is most advantageous to apply the heating-power-oriented engine control measures in different phases with and without external exhaust gas recirculation and to operate them depending on the warm-up criteria of the engine and / or the coolant and / or the components or component surfaces that come into contact with the recirculated exhaust gas.

[0089] A particularly advantageous variant consists in the engine control unit 20, after a cold start, during warm-up with a cabin heating deficit below a warm-up criterion of the engine 1 or the charge air cooler 31k and / or an EGR cooler 3 in the low-pressure EGR branch 11lpegr, keeping the low-pressure EGR branch 11lpegr closed by means of an EGR valve 14 and adjusting an exhaust gas throttle valve 31dk in the main exhaust gas flow 10ft downstream of the exhaust gas extraction point of the low-pressure exhaust gas recirculation towards a strong throttle, so that increased internal exhaust gas recirculation heats the coolant more quickly, preferably in conjunction with a shift in injection timing that increases fuel consumption. Above this warm-up criterion, the engine then switches to normal operation and, depending on requirements, adjusts EGR rates to optimize fuel consumption or emissions.With this approach, a sufficiently high temperature value for the warm-up criterion ensures that the cabin heating criteria can still be met after switching over.

[0090] To further improve the cabin heating effect and also to reduce fuel consumption, the low-pressure exhaust gas recirculation in branch 11lpegr is preferably activated via the EGR valve 14 when the warm-up criterion is exceeded, and at the same time, in conjunction with a moderately throttled exhaust gas throttle valve 31dk, the target values ​​of the EGR rates, in particular cabin heating performance-oriented EGR rates of more than 40%, are set.

[0091] For reasons of drivability, soot and smoke emissions, it is not always possible to implement significant throttling with the exhaust-side valve 31dk during the very early winter engine warm-up. In many cases, this is because the initially very high engine friction already requires a relatively large amount of fuel, thus limiting the possibilities for high internal EGR, especially when there is also a certain road load and / or incline.

[0092] Furthermore, it is often desirable / necessary to preheat the charge air cooler 31k and as many of the components that will come into contact with recirculated exhaust gas during the subsequent activation of the external exhaust gas recirculation (EGR) before activating it. This can be achieved at least locally at the EGR cooler 3 by the preheated coolant while the EGR is still deactivated, and possibly also at the cooler itself if it is water-cooled.

[0093] Against this background, it is particularly advantageous or sometimes even necessary – either as support for the described local coolant-side preheating or on its own – that during the very early warm-up phase, with the external EGR deactivated, a high fresh air mass flow at high boost pressure and thus increased temperature ensures that as many of the surfaces as possible that will later come into contact with the recirculated exhaust gas are preheated.

[0094] This temporarily corresponds to the operating procedure according to DE 10 2009 042 745.7.

[0095] In turbocharged engines, it is particularly advantageous to apply heating-performance-oriented engine control measures that increase the exhaust gas temperature and exhaust gas enthalpy before the turbocharger, thus generating a particularly high boost pressure and a particularly high fresh air mass flow.

[0096] In this phase, it is particularly helpful if a device 31b or 31sv is available that deactivates the charge air cooler 31k. This deactivation can be carried out on the coolant side, or, in the case of an air-cooled charge air cooler, also on the cooling air side via a radiator shutter.

[0097] As warm-up criteria for defining sufficient warm-up, in addition to charge air or coolant temperature values, computational models can be used. These models calculate the boost pressure range based on the enthalpy flow curves, determining when sufficient warm-up is achieved, for example, to reliably prevent condensation before the compressor 31tv and / or in the charge air cooler 31k. Simple time specifications or data on the fuel burned since engine start or on the coolant temperature can also be used, provided a suitable safety margin is maintained. For many engines, it is quite possible to simply set a coolant temperature of 25°C or even below, particularly in the range of 0-25°C, as the threshold at which the first cabin heating-oriented operating phase with a high fresh air mass flow is terminated.Defining this switching coolant temperature, or another switching criterion, based on the ambient temperature and / or humidity is also advantageous here. In this context, it is particularly helpful that the absolute humidity is relatively low when cabin heating demand is especially high, e.g., at -10°C or even -20°C. Therefore, a precise analysis reveals that, precisely when cabin heating demand is high, the criterion can be extended to allow for earlier switching.

[0098] Even if the procedure with high boost pressure and fresh air mass flow should be limited in time due to relatively large exhaust losses in order to minimize increased fuel consumption, it may be advantageous to return to this state after longer driving periods, e.g. if there is a risk of component icing or if drying of the charge gas system is desired.

[0099] In engines with devices for adjusting the valve timing of the charge exchange components, it is particularly advantageous to support operation with closed external EGR and high internal EGR by means of appropriate valve timing.

[0100] Particularly preferred are high residual gas quantities with high exhaust back pressure of valve 31dk in the case of very high cabin heating requirements; high residual gas quantities with low exhaust back pressure of valve 31dk are preferred in the case of less high auxiliary heating requirements.

[0101] Although the use of multiple phases with different cabin heating-performance-oriented engine control measures is particularly advantageous in terms of drivability, operational safety / contamination risk and fuel consumption, this combination of different phases is often only to be seen as an improvement option.

[0102] In some engines / vehicles, in the simplest case, it is sufficient that, compared to normal engine operation, the relevant cabin heating performance-oriented engine control measures are a permanent closing of the EGR valve 14 and a maximization of the engine's internal EGR rate by throttling the exhaust gas throttle valve 31dk and / or adjusting the timing of the engine intake and / or engine exhaust valves.

[0103] The simplicity and relatively low application costs, possibly utilizing the existing combustion fresh air mass flow control, make this approach particularly attractive. If necessary, the increased combustion chamber pressure at the time of injection also keeps the effort required to slightly increase the heating output by adjusting the injection timing manageable.

[0104] A particular advantage of the inventive method lies in its ability to improve cabin heating performance, especially during engine idle, overrun, and downhill driving. The throttling effect of the exhaust-side valve 31dk with the EGR valve 14 closed significantly contributes to this improvement. It not only results in higher charge exchange work and thus higher base fuel consumption, but also, via the increased internal EGR, in a further increase in component temperatures, combustion chamber pressure, and the scope for adjusting injection timing in a cabin heating-performance-oriented manner.

[0105] Especially in urban traffic with frequent longer periods of vehicle standstill at idle, the auxiliary heating operation according to the invention with closed EGR valve 14 and exhaust gas flow throttled by means of valve 31dk is of particular interest.

[0106] Even in vehicles where, for reasons of driving dynamics – the boost pressure, especially in turbocharged engines, is usually somewhat lower when throttled with valve 31dk due to the throttling at the EGR branch even when valve 14 is fully open, and the maximization of the fresh air quantity builds up with a slight delay due to the nature of the principle – throttling the exhaust mass flow during driving is sometimes undesirable, it can at least make an important contribution to improving cabin heating performance during prolonged engine idling or overrun and / or downhill driving with engine loads near / less than zero.

[0107] In particular, the freely available exhaust-side throttling device makes it possible to meet specific cabin heater approval tests of some vehicle manufacturers. This applies especially to winter heating and defrosting tests performed with the vehicle stationary and the engine idling.

[0108] It is particularly helpful to increase the engine idle speed and to implement the throttling according to the invention with the external EGR closed. To temporarily increase cabin heating performance, the engine idle speed is preferably increased by at least 30% relative to operation without heating-performance-oriented engine control measures when the vehicle is stationary, and in particular to more than 1400 rpm. This improves the heat input on the coolant side not only through the higher engine speed and the higher frictional power, but also through the increased charge exchange losses. At the same time, the increased speed provides more scope for adjusting the injection parameters to improve cabin heating performance, especially due to the higher excess air and the simpler handling of the smooth running criteria.

[0109] Against this background, it is particularly attractive for some engines / vehicles that the inventive use of exhaust-side throttling by means of the valve 31dk with the EGR valve 14 closed is applied exclusively in engine idle mode when the vehicle is stationary and / or in overrun mode and / or when driving downhill with engine loads near / less than zero.

[0110] The inventive method is adaptable to suit a wide variety of engines with low-pressure EGR. The use of existing devices for deactivating the external EGR (14, 14hd) and for metering the external low-pressure EGR (14 together with 31dk) ensures that a positive cost / benefit ratio can always be achieved through improved heating comfort.

[0111] Nevertheless, the inventive method is particularly aimed at saving the costs of air-side PTC auxiliary heaters or other expensive auxiliary heating hardware. Depending on the engine / vehicle combination and the permissible target value for increased fuel consumption, various combinations of measures according to the invention are available for this purpose. The devices or device settings according to the invention are therefore of particular interest when they are assigned to a vehicle, especially a vehicle with a diesel engine and low-pressure EGR, which does not have an electric PTC auxiliary heater for heating the cabin air.

[0112] In particular, for reasons of heating performance and / or fuel consumption and / or feasibility, it is often helpful and / or necessary to use additional measures to increase heating performance on the cooling circuit side and / or on the heating circuit side in accordance with patent application DE 10 2009 042 745 A1.

[0113] By carefully applying the inventive concept, it becomes possible to achieve previously unimaginable improvements in cabin heating performance by means of cabin heating performance-oriented engine control measures and / or to reduce the associated increase in fuel consumption to previously unimaginable levels.

[0114] This already applies to applications without the bypass line 11dkby according to the invention for improved exhaust gas utilization at the EGR cooler 3, e.g. according to the Fig. 4-6, and especially with such a bypass line 11dkby, which provides an additional benefit when the EGR valve 14 is closed and, depending on the system design, also when the EGR valve 14 is open.

[0115] Against this background, it is important to know that in today's diesel passenger cars, the operation of a mass-produced, air-side PTC auxiliary heater with approximately 1.0 kW of electrical power requires a primary energy input of QPKT in the form of fuel via the engine / generator efficiency chain. Brst = mpkt Brst * Hu = 4 - 5 kW is required. The mpkt Brst the fuel mass flow and H U The lower heating value. Since the electric PTC auxiliary heater is almost always in operation during the first 15 minutes of winter city traffic when ambient temperatures drop below +5°C, this very often results in a corresponding increase in fuel consumption.

[0116] Previous attempts to replace, for example, a 1.0 kW electric PTC auxiliary heater in standard production vehicles solely through heating-output-oriented engine control measures, while retaining the standard components in the cooling and heating circuits, often failed due to insufficient heating output, especially during the first 15 minutes. In addition to other difficulties with these approaches, the increased fuel consumption—despite the inadequate improvement in cabin heating performance—is significantly higher than the 4-5 kW primary energy input of the 1.0 kW PTC auxiliary heater.

[0117] Therefore, previous patent applications by the applicant aim to simultaneously modify the cooling and heating circuit, and in particular the heating heat exchanger and the local heating of the individual heat-active masses (water, metal, oil, hoses, etc.), in such a way that as few or no heating-power-oriented motor control measures as possible are required.

[0118] This usually involves a certain amount of component and development effort and is often only feasible for series production with relatively long-term planning.

[0119] In comparison, the present invention can be implemented with relatively few or no hardware changes and can therefore be integrated into ongoing developments relatively quickly.

[0120] In particular, with some engines, at least sufficient cabin heating performance can be achieved by accepting a relatively high fuel consumption, so that money can be saved on the PTC auxiliary heater.

[0121] In particular, the inventive procedure aims in a second step to optimize the hardware and the heating-performance-oriented engine control measures in such a way that the fuel consumption is improved despite the elimination of the PTC auxiliary heater while maintaining the same heating comfort, and in particular that the cost savings achieved by eliminating the PTC auxiliary heater are not offset by the costs of additional components.

[0122] The inventive method, utilizing the existing components 14 and 31dk, makes a significant contribution to cost optimization. To measurably differentiate the improvement according to the invention from the prior art, the increased fuel consumption in two standard tests commonly used in passenger car development can be used, for example.

[0123] Firstly, this involves a drive in the ECE cycle at an ambient and starting temperature of -7°C, i.e., during the approximately 13-minute ECE phase of the MVEGA or MVEURO test to determine pollutant emissions and fuel consumption. Secondly, it involves the well-known VDA heating test at 50 km / h at -20°C. It is very helpful that these tests can be performed by most exhaust gas test rigs or climate wind tunnels.

[0124] While meeting current heating comfort and defrosting criteria, a particularly good compromise between increased fuel consumption, costs, and benefits is achieved when the inventive method is applied and when it is coordinated with regard to component complexity and / or application such that the increased fuel consumption in ECE operation representing urban traffic according to the conditions of the statutory emissions test (MVEGA / MVEURO), but with ambient and starting temperatures of -7°C and a cabin heating setting at full heating comfort, is no greater than the difference in fuel consumption that results from operating an identical vehicle with the addition of an air-side electric PTC auxiliary heater providing the same level of heating comfort. In particular, it is advantageous if the difference in fuel consumption with and without heating-performance-oriented engine control measures is less than 15% and / or 1.5 l / 100km.Depending on the base engine, this target value can also drop to values ​​of 5% or less.

[0125] The inventive method makes this possible, particularly with component costs that ultimately result in savings in the double-digit euro range. With a correspondingly lower component cost, it is even possible to reduce fuel consumption to relatively close to zero.

[0126] The target values ​​for fuel consumption according to the invention in the ECE cycle are based, not least, on the fact that in today's passenger cars with a diesel engine of, for example, 2 liters displacement, depending on the vehicle weight, approximately 10–20 kW of primary energy is converted on average in the ECE cycle, which starts at -7 °C, until the commencement of the extra-urban driving section (EUDC), without a PTC auxiliary heater. Experience has shown that an activated PTC auxiliary heater is generally permanently switched on during the ECE phase due to the slow engine warm-up. Thus, a 1.0 kW auxiliary heater with its 4–5 kW primary energy requirement has a very significant impact compared to the 10–20 kW of primary energy required without a PTC auxiliary heater.

[0127] Following an analogous procedure to the ECE cycle, optimization can also be carried out in such a way that the fuel consumption increase averaged over the first 15 minutes in the standard heating test according to VDA at 50 km / h in the highest smoothly drivable gear at ambient and starting temperatures of -20°C and a cabin heating setting of full heating comfort, is not greater than the difference in fuel consumption that results from operating an identical vehicle by adding an air-side electric PTC auxiliary heater with the same heating comfort, and in particular that the difference in fuel consumption with and without heating-performance-oriented engine control measures is less than 10% and / or 0.7 l / 100km.

[0128] The upper limits specified for the fuel consumption increase of the heating-performance-oriented engine control data for the ECE test at -7°C and the VDA test at -20°C, when the heating performance criteria are fully met including the elimination of the PTC auxiliary heater, are at such a low level, especially with relatively small changes to the cooling and heating circuit - and thus with relatively low costs - that the inventive method sets completely new standards for cabin heating systems or heating-performance-oriented engine control measures.

[0129] In conjunction with a corresponding increase in effort for the components and in the application, the inventive method makes it possible in particular to achieve the heating performance with a PTC auxiliary heater without the fuel consumption being significantly greater than with the PTC auxiliary heater switched off and thus a significantly colder cabin.

[0130] As described above, the inventive method is not limited to saving as much fuel as possible and can in particular also be used in such a way that the increased fuel consumption does not play a dominant role and only the fulfillment of the heating performance criteria at minimal costs is paramount.

[0131] The previous applications / considerations according to the invention have initially focused primarily on potential future turbocharged engines with low-pressure EGR systems and, in conjunction with the additions described below and in further claims, may even play a significant role in making low-pressure EGR systems more desirable in the future.

[0132] In particular, the inventive concept can also be applied to today's turbocharged passenger car mass-produced engines, in which external EGR systems are currently designed as high-pressure EGR systems and, as a rule, no valve 31dk is present in the main exhaust stream 10ft: In this case, however, an exhaust throttle valve 31dk, controllable by the engine control unit 20, must be added to the main exhaust stream 10ft as standard. Depending on the application, this may just be cost-effective, e.g., if a very expensive auxiliary heater can be replaced. As a rule, however, this will rather lead to a negative cost / benefit balance, since throttle valves 31dk in the main exhaust stream are relatively expensive.

[0133] In contrast to a conventional exhaust gas throttle, which in some cases is used not only in trucks but also in large-displacement passenger car diesel engines specifically for cabin heating purposes – in truck diesel engines, this is primarily used as an engine brake – the method according to the invention differs in particular in that the throttle valve 31dk, when used as a support measure for cabin heating, induces a significantly lower increase in fuel consumption. This applies especially in all cases where the control of the valve 31dk according to the invention is such that, through the artificially accelerated warming of the engine or the engine cooling system and especially the EGR cooler 3 by means of the engine control unit 20, the first EGR control valve 14 is opened considerably earlier during warm-up than without the measures according to the invention for increasing waste heat.

[0134] In general, it should be noted that with high-pressure EGR systems, excessive throttling with a valve 31dk in the main exhaust gas stream ia is no longer readily possible when the high-pressure EGR path is opened by means of valve 14, but in some applications it is also not necessary with the inventive procedure for fulfilling the cabin heating requirements.

[0135] With the introduction of further improvements according to the invention, which in a first step can again be implemented particularly cost-effectively especially in low-pressure EGR systems with exhaust-side EGR throttle valve 31dk, the above cost assessment for the introduction of an additional valve 31dk in high-pressure EGR systems also improves significantly once again: Firstly, this concerns the additional installation of an exhaust-side bypass branch 11dkby for using the EGR cooler 3 as a heat source for the coolant when the first EGR control valve 14 is closed. According to the invention, this operating mode is achieved in particular by means of exhaust gas extraction downstream of the EGR cooler 3 and introducing this extracted exhaust gas downstream of the second EGR control valve 31dk into the main exhaust stream 10ft.

[0136] Secondly, this concerns the optimized use of a thermoelectric generator in the EGR branch for power generation with reduced / deactivated EGR.

[0137] In both cases, the valve 31dk in the main exhaust stream 10ft is a crucial means of providing a sufficient exhaust-side pressure differential so that the EGR cooler 3 or the thermoelectric generator 3teg (TEG) can still be supplied with hot exhaust gas even with reduced / deactivated exhaust gas recirculation, thus making exhaust gas heat available, for example, for cabin heating purposes and / or for generating electricity.

[0138] In both cases, the opening of the first EGR control valve 14, which according to the invention is made possible particularly early during warm-up, in turn improves the utilization of the exhaust gas for engine or cooling system heating by reducing the exhaust gas mass flow leaving the overall system via the main exhaust branch 10ft. At the same time, the EGR cooler 3 or the TEG (3teg) is utilized more efficiently.

[0139] The improved utilization lies not only in the fact that the exhaust gas still flows through components 3 and 3teg when valve 14 is closed, transferring heat to the coolant or generating electricity before leaving the overall system, but primarily in the fact that a particularly high exhaust gas volume flow through components 3 and 3teg can be achieved by opening valve 14 earlier. The exhaust back pressure, which must be set using valve 31dk, inevitably decreases as soon as valve 14 begins to open.

[0140] In extreme cases, the EGR branch 11eff and the bypass branch 11dkby are already open after a few minutes even at a starting temperature of -20°C, and the valve 31dk and / or the valve 14 regulates the desired EGR volume flow.

[0141] During a constant driving speed of 50 km / h at an ambient temperature of -20°C and a heating setting for maximum heating comfort according to the operating instructions or for automatic operation with a setting of +22°C interior temperature ("Auto 22°C") with a turbocharged 4-cylinder diesel engine of approximately 1.8-2.2 l displacement, it is particularly advantageous, after completion of the accelerated warm-up according to the invention with valve 14 closed, e.g. after 2-5 minutes of driving time, to partially or completely open the valve 14 and activate the exhaust gas recirculation.

[0142] Starting from a base engine with, for example, approximately 30 g / s fresh air mass flow at this 50 km / h operating point with valve 14 closed and valve 31dk open, it is particularly advantageous to reduce the fresh air mass flow to 20 g / s or even 10-15 g / s by opening valve 14 and partially or completely closing valve 31dk.

[0143] The reduction of the fresh air mass flow to, for example, 15 g / s means for current and probably also future EGR coolers (3, 3teg) that even when the valve 31dk is completely closed, only a comparatively low exhaust back pressure builds up, as long as the branch 11dkby is open and is designed for similar or lower pressure losses as the branch 11eff.

[0144] In particular, it is possible - at least for low-pressure EGR systems - to pump approximately 25-30g / s of exhaust gas through the EGR cooler or TEG (3, 3teg) at the operating point chosen here at 50 km / h with relatively little exhaust back pressure and then distribute it to the branches 11dkby and 11eff.

[0145] With a recirculated exhaust gas temperature of, for example, 250°C, this corresponds to an exhaust gas-side heating potential of approximately 5-6 kW at, for example, a cooling water temperature of 50°C. Even if, taking into account the temperature differences required for heat transfer, only 50% of this is usable, 2.5-3.0 kW still remain as heat input into the coolant.

[0146] This is highly interesting from the perspective of TEG, at least if the exhaust back pressure does not negate the fuel consumption advantages of the TEG.

[0147] On the other hand, an additional heat source of 2.5-3 kW on the coolant side is highly interesting for cabin heating, especially if it is located outside the engine and directly in front of the cabin heating heat exchanger.

[0148] With appropriately powerful dimensioning of the heating heat exchanger 4 and operation of the heating heat exchanger close to thermal saturation and in particular by reducing the coolant flow rate to values ​​which, with the current air flow rate, still lead almost to thermal saturation, 2.5-3.0 kW of additional water-side heat means a very significant improvement in the current cabin heating performance.

[0149] Especially when the airflow through the cabin heat exchanger 4 is relatively small, operating situations occur relatively frequently in practice where the heating heat exchanger is in thermal saturation and a relatively small coolant flow through the EGR cooler with 2.5-3.0 kW heat output is better for maximizing the cabin heating effect than a very large coolant flow.

[0150] In practice, relatively small airflows are often present in the heating heat exchanger, especially during the first few minutes of engine warm-up in very cold ambient conditions, particularly when the air conditioning is operating automatically. This is because the system deliberately avoids cooling the driver's footwell instead of warming it. For this purpose, the cabin airflow is usually automatically reduced, and the remaining airflow is primarily directed towards the windows to prevent them from fogging or icing up.

[0151] At low engine load and with slow coolant warm-up, this so-called cold start phase can last 3-5 minutes, and in some vehicles, especially when driving downhill, even considerably longer. During this phase, an additional 2.5-3.0 kW of heat energy in the coolant downstream of the engine and upstream of the heater core is a highly efficient way to improve heating comfort, particularly when combined with a reduced coolant flow rate of less than 10 l / min, or even preferably 2-6 l / min in high-performance heater cores. The improved effect is due to the increased heating supply temperature achieved by the additional 2.5-3.0 kW.

[0152] In this context, a particular advantage of the inventive method is that this 2.5-3.0 kW of additional heat is available relatively early in the warm-up phase, and, at least in some applications, no longer requires high exhaust back pressure to maintain it during the further warm-up phase.

[0153] In particular, there are also a number of applications according to the invention where it is ultimately most advantageous to increase the pressure losses in branch 11dkby at least temporarily or to close this branch temporarily, e.g. by means of a combined 3-way valve 14 for branches 11eff and 11dkby or with a separate valve in branch 11dkby.

[0154] This is particularly the case when maximizing cabin heating is the priority and increased exhaust back pressure is desired and / or maximizing the TEG effect in warm conditions, which requires minimizing pressure loss in branch 11dkby, but at the same time a throttling effect to adjust the EGR and / or avoid component or cooling system overheating.

[0155] Of particular importance in this context, as well as with regard to costs and the required installation space, is the further design according to the invention, which does without a direct switching capability of the branch 11dkby by means of the motor control 20 and relies only on a relatively high throttling in this branch.

[0156] Against this background, the use (introduction) of the valve 31dk in the main exhaust stream 10ft according to the invention has a greatly expanded scope of application if a branch 11dkby and / or a TEG are included in the overall considerations.

[0157] With regard to cost / benefit analysis, the combination according to the invention offers a solution. 2. a low-pressure EGR system with a second EGR control valve 31dk already present in addition to the first EGR control valve 14 and 3. a bypass line 11dkby, in particular as a permanently open line with strong throttling as overheat protection and simultaneously as a means of increasing heating performance and / or EGR cooler drying, and 4. An EGR cooler 3 or EGR cooler with integrated TEG (3teg) offers a previously untapped synergy. This applies in particular to the fact that even with reduced / deactivated EGR, engine waste heat is utilized and can be metered within certain limits by means of valve 31dk.

[0158] This benefit is so great in many applications, especially when using an EGR-TEG 3teg, that even the introduction of an additional valve 31dk is often still cost-effective if the principle of high-pressure EGR is not to be abandoned.

[0159] This is especially true if expensive auxiliary heaters can be avoided and / or if fuel consumption is in the customer's hands, i.e., also outside of the emissions test, plays an important role.

[0160] The increase in heating performance relative to the increase in fuel consumption with and without engine control measures is so much better in particular because waste heat is already utilized when the first EGR control valve 14 is closed, and furthermore the EGR can be activated earlier, since the EGR cooler and part of the EGR path are preheated more quickly on the coolant side or exhaust gas side even when valve 14 is closed.

[0161] This advantage is a particularly welcome effect for low-pressure EGR, among other things because the risk to the compressor 31tv due to unwanted droplet formation in the EGR branch can be controlled more reliably.

[0162] In principle, a wide variety of configurations for line 11dkby are conceivable and feasible, as are various options for its activation / deactivation and for overheating protection of the EGR cooler or TEG. For example, it is possible to design valve 14 as a three-way valve, which can shut off branch 11dkby if necessary.

[0163] However, it is particularly simple and especially cost-effective with regard to increasing heating performance and / or preheating or drying the EGR cooler on the exhaust gas side (3, 3teg) to design branch 11dkby as a small permanently open bypass pipe. For example, a conventional EGR pipe – which in modern passenger car diesel engines typically has cross-sections of approximately 22–28 mm in diameter – can be used, along with a perforated orifice plate 11drbl to restrict the flow.

[0164] The flow limitation is particularly important to ensure that the EGR cooler 3 is not overloaded during EGR operation and / or that the leakage flow in branch 11by does not lead to overheating of the EGR cooler 3 or the vehicle cooling system, at least when valve 14 is closed and valve 31dk is fully open, i.e., at engine rated power.

[0165] The orifice plate 11drbl is particularly preferably designed to have a smaller flow cross-section and / or a significantly higher pressure loss coefficient than the fully open valve 14. Typically, this smaller cross-section of the orifice plate 11drbl is particularly preferably less than 50% of that of the fully open valve 14, in order to make the flow rate in branch 11dkby significantly lower when the valve 14 is fully open than in the EGR branch 11eff.

[0166] In particular, the smaller cross-section of the orifice plate 11drbl is more than 5-10% of the fully open valve 14 in order to reliably avoid a potential risk of clogging due to deposits.

[0167] Such a design will lead to baffles smaller than 12 mm, and often even in the 5-10 mm range, particularly in many passenger car engines. In such cases, it is especially advantageous to locally design the EGR line 11dkby with pipes having a significantly reduced flow cross-section. Pipe diameters of less than 15 mm are often suitable here.

[0168] Depending on the application, especially when the primary goal with valve 14 closed is to throttle the engine via valve 31dk to increase charge pressure losses, and / or to preheat / dry the EGR cooler (3, 3teg), pipe diameters of 5-12 mm are often particularly advantageous. Even with relatively long pipes 11dkby of several hundred mm in length, such internal pipe diameters can still be used to advantage, especially if throttling the charge exchange is desired anyway to increase cabin heating performance.

[0169] It is particularly advantageous that the comparatively small pipe diameters allow for a particularly simple and cost-effective pipe design / bending, and can also be more easily routed along narrow and winding building spaces, and are also easier to thermally insulate.

[0170] Particularly for reasons of cost and / or installation space, in some applications only the inventive dispensing with a valve functionality for closing the branch 11dkby and / or the particularly small line diameters of the branch 11dkby will make it possible to realize the line 11dkby.

[0171] The inventive method is explained in more detail below using some examples, without limiting the invention to these examples.

[0172] Fig. Figure 1 shows a particularly advantageous embodiment of an engine and vehicle cooling system for carrying out the method according to the invention with an internal combustion engine 1 and the two relevant valve devices 31dk in the main exhaust stream and 14 in the low-pressure EGR branch, without the inventive procedure being limited to such a cooling system.

[0173] The combustion engine 1 is supplied with combustion air via the fresh air line 10f, through which the compressor 31tv of the turbocharger draws in and compresses the air. The compressed air is then selectively conveyed by means of the switching valve 31b either through the bypass path 10b, which is optionally equipped with additional electric air heating, or through the charge air cooler 31k, which, due to the low-pressure EGR, will subsequently be referred to more precisely as the charge gas cooler 31k. The air tempered according to the invention, or the EGR fresh air mixture, then flows via line 10ab and line 12 to the individual cylinders of the engine 1.

[0174] When the EGR is activated by partially / fully opening the EGR valve 14 and, if necessary, partially closing the exhaust-side throttle valve 31dk, the fresh air from branch 10f mixes with the recirculated exhaust gas from the EGR branch 11(11lpegr) upstream of or within the turbo compressor 31tv. A suitable position of the throttle valve 31dk ensures a sufficient pressure differential so that the EGR valve 14 can adjust the desired EGR rate. The control function can optionally also be performed by the exhaust throttle valve 31dk, either at a predetermined opening position of the EGR valve 14 or through mutual interaction / adjustment.

[0175] In turbodiesel engines, the external EGR rate is typically zero at engine start and is only activated after a certain warm-up period, especially at very low ambient temperatures, and then gradually increased. During this time, the system heats up / dries. Fig. 1 the compressed / heated air the air intake system downstream of the compressor 31tv.

[0176] In the example in Fig. 1 is an example of an optional charge air cooler deactivation 31b on the charge gas side via a bypass path 10b, which is of particular advantage for energy-related and also pollution-related reasons.

[0177] Alternatively, an intercooler louvre can be used for this purpose, or as in Fig. Figure 3 shows a deactivation on the coolant side with water-cooled charge air.

[0178] While the option to deactivate the charge air cooling is not essential to the invention, it significantly helps to limit heat losses to the environment, improves component preheating, and reduces the risk of condensation, especially in low-pressure EGR systems. Furthermore, increasing the charge air temperature reaching the engine allows for a wider adjustment range for potentially modifying injection parameters to improve heating performance.

[0179] The in Fig. 1 The low-pressure EGR system shown has a water-cooled EGR cooler 3 and an EGR valve 14 as well as important measuring and control lines 20a-20e of the engine control unit 20.

[0180] The coolant is circulated through the engine 1 by the engine's coolant pump 7. From the engine outlet, the coolant flows in a first circuit 9a to the water reservoir 9 and then back to the engine 1 via the thermostat 6. This circuit serves for ventilation and degassing and, to minimize heat loss during warm-up and ensure reliable degassing, includes a restrictor (not shown) to reduce the coolant flow rate to near zero at low engine speeds. Alternatively, a two-way valve can be used instead of the restrictor for even more precise control or temporary shutdown during warm-up.

[0181] A second branch of the cooling system runs via line 6a and the vehicle radiator 8 to the thermostat 6, or via the bypass branch 6b, which can be switched using the optional engine control line 20c and includes an optional switching valve 6bv, directly to the thermostat 6. Above a certain operating temperature, the thermostat 6 gradually opens the radiator branch 6a and closes the bypass branch 6b in a similar manner. Alternatively, a control valve 6, controlled by the engine control unit 20 according to the cooling requirements, can be used instead of the conventional thermostat 6, optionally with the additional integration of the optional bypass valve 6bv.

[0182] In addition to branches 6a, 6b, and 9a for engine cooling and / or venting of the cooling system, branch 4a serves to heat the vehicle cabin. The coolant is pumped by the optional electric auxiliary pump 2 via the EGR cooler 3 and the temperature sensor 15 to the cabin heat exchanger 4 and then back to the radiator thermostat 6.

[0183] The inventive method aims to Fig. 1 in its fuel consumption-optimized version to meet cabin heating performance requirements, in particular aims to reduce the time until the EGR is activated and to enable high EGR rates as quickly as possible.

[0184] However, the inventive method is also advantageously usable for engines that do not want to activate the EGR temporarily for other reasons, e.g. due to sooting or because of the risk of condensation and / or icing and / or because an exhaust gas heat exchanger downstream of the turbo is to be used optimally and / or the exhaust system is to be brought to a higher temperature level.

[0185] In particular, it is also possible to adjust the system according to Fig. 1 only to be used for implementing measures according to the invention as described in DE 10 2009 042 745 A1. For this purpose, for example, the throttle valve 31dk can be included in the EGR control after activation of the EGR and provide a required pressure differential, or it can be completely open and a suction-side valve 31sdk takes over the tasks according to DE 10 2009 042 745 A1 in order to ensure high EGR rates during the warm-up phase. This can also be seen, for example, in a comparison of Fig. 2 with Fig. 7 of DE 10 2009 042 745 A1, which are largely identical.

[0186] However, it is particularly advantageous if systems are used in Fig. 1 according to the current invention description, in the first minutes of warm-up, a lower fresh air and exhaust gas mass flow is used compared to DE 10 2009 042 745 A1, by throttling the exhaust-side throttle valve 31dk and yet setting the highest possible boost pressures in line 11ab by the engine control 20.

[0187] In conjunction with appropriately designed / set valve timing of the charge exchange valves for low / no valve overlap and suitable turbocharger settings, systems according to Fig. 1. In particular, exhaust-side throttling with the throttle valve 31dk is possible without the turbocharger boost pressure dropping too much relative to the exhaust back pressure. This applies to operation with the EGR valve 14 open and, with certain limitations, also with the EGR valve 14 closed and / or regulating.

[0188] In the particularly effective procedure of this supplementary application, all exhaust gas exiting the engine flows according to Fig. 1 via the turbine 31tt of the exhaust gas turbocharger and is partially or completely conveyed via the main exhaust line 10ft to the exhaust aftertreatment system 31dpf, e.g. with oxidation catalyst and diesel particulate filter 31dpf, depending on the EGR rate.

[0189] The non-recirculated exhaust gas flows through the throttle valve 31dk before exiting into the environment, passing through the exhaust sound attenuation components (not shown) and, if applicable, other exhaust aftertreatment components.

[0190] Depending on requirements and operating strategy and depending on the engine and engine operating condition, the opening degree of the EGR valve 14 and the throttling set at the exhaust throttle valve 31dk set EGR rates from zero to high EGR rates in the range of 40-75%.

[0191] The optional intake-side throttle valve 31sdk in Fig. 1 may be used in special operating situations, such as during DPF regeneration, to throttle and, if necessary, to safely shut off the fresh air mass flow and is generally open in the inventive procedure for increasing cabin heating power.

[0192] It comes into play, for example, particularly when a high exhaust gas temperature with a low fresh air and exhaust gas mass flow is especially advantageous during diesel particulate filter (DPF) regeneration. This reduces the energy required to raise the exhaust gas temperature from, for example, 200°C during normal operation to over 550°C during DPF regeneration and / or reliably prevents an unacceptably high heat input into the coolant during DPF regeneration. In this operating mode, the reduced gas-side pressure and the reduced gas-side density within the engine and exhaust system, achieved by means of the throttle valve 31sdk, in conjunction with the closing of the EGR valve 14, help to reduce the heat input into the coolant and, in particular, to lower the heat radiation from the exhaust system to adjacent components.

[0193] The arrangement according Fig. In this context, 1 offers - in the case of using a valve 31sdk - the particularly advantageous option of operating the DPF regeneration with the EGR valve 14 closed either via the fresh air mass flow limitation through the intake-side throttle valve 31sdk with minimized risk of overheating, especially when the vehicle is at operating temperature, or via the exhaust-side throttle valve 31dk with a focus on better cabin heating performance and / or less dilution of the engine oil by fuel.

[0194] Especially with regard to reducing engine oil dilution, the exhaust-side throttling of the fresh air mass flow with the EGR valve closed is particularly advantageous because it ensures better heating of the engine and the engine oil and, via the increased charge density and, if applicable, the increased charge temperature at the injection time, results in a lower penetration depth of the fuel droplets towards the combustion chamber wall.

[0195] The position of the in Fig. In the inventive procedure for improving the cabin heating effect, the optional intake-side throttle valve 31sdk can optionally also be located downstream of the turbo compressor 31tv.

[0196] Alternatively, its function to reduce costs can be limited to serving as a safety engine shut-off with a simple on / off function.

[0197] In systems designed for complete closure or sufficient pressure resistance and tightness, and depending on the exhaust aftertreatment system, the valve 31sdk can be completely omitted in some engines to save costs; the exhaust-side valve 31dk then serves as a safety engine shut-off when completely closed.

[0198] In a particularly easy-to-implement approach based on the inventive concept, the system is designed according to Fig. 1. In case of cabin heating power deficit, simply close the EGR valve 14 - a simple on / off valve may also suffice - and the exhaust throttle valve 31dk ensures increased charge exchange work and / or an increased engine-internal EGR rate.

[0199] Compared to normal operation with the highest possible air mass flow and / or the highest possible external EGR rate, this often means, especially in turbocharged engines under lower partial load, that the turbocharger has a slightly lower speed and usually takes a little longer to build up the same full load boost pressure as without the exhaust-side throttling.

[0200] However, if an analogous strategy for ensuring drivability is applied here, as is already standard practice today for regenerating the DPF filter with intake-side throttling, then comparable drivability can also be ensured with the exhaust-side throttling according to the invention.

[0201] It is particularly advantageous with regard to drivability if the engine control unit 20 - e.g. based on acceleration pre-conditions - ensures that there is always enough time to deactivate the exhaust-side throttling to increase cabin heating power so quickly that the driver does not notice any difference to normal operation when jumping to full load.

[0202] Since engine idling is often problematic for cabin heating, especially when the vehicle is frequently and / or for extended periods stationary, the inventive method proposes, in particular, to implement the inventive increase in heating performance by throttling with the exhaust-side valve 31dk – which is already present during normal operation, for example, due to the low-pressure design of the EGR system – exclusively when the vehicle is stationary, and in particular to increase the engine idle speed. In this context, engine idle speeds of 1100–1500 rpm are quite achievable when there is a high demand for cabin heating. The smooth running of modern engines and the sound insulation provided by the vehicle allow for this in many vehicles.

[0203] As soon as the engine control unit recognizes that the journey should continue, e.g. by releasing the foot or hand brake or by pressing the clutch pedal in a stationary vehicle, it switches to normal operation or acceleration-optimized operation.

[0204] Apart from the application effort, this approach is cost-neutral and, above all, eliminates potential concerns regarding drivability. It is particularly helpful precisely where, without the exhaust gas throttling according to the invention by adjusting the injection timing, only a comparatively small increase in heating output can be achieved by modifying the injection or ignition timing due to the low base fuel mass flow. This applies especially to operating points where the increase in heating output is achieved by exhaust-side throttling with the EGR valve 14 closed, as well as to operating points where exhaust-side throttling with activated external EGR, i.e., with the EGR valve 14 open / partially open, is used to increase cabin heating output while reducing fuel consumption.

[0205] In the variant with closed EGR valve 14, the limitation according to the invention of the heating power-oriented engine control measures to situations with a stationary vehicle eliminates in particular all potential concerns regarding the sooting / contamination of the components that come into contact with the external EGR.

[0206] At the same time, increasing the charge exchange work and the internal EGR rate, and increasing the gas-side pressure and gas-side temperature at the injection time, increases the scope for additional heat input via the heating power-oriented adjustment of the injection times.

[0207] In summary, this method ensures in particular that the exhaust gas temperatures at the oxidation catalyst are high enough and, for example, above the operating temperature of 200°C, thus ensuring extensive post-oxidation of unburned exhaust gas components.

[0208] All of this applies even at conventional engine speeds, but especially at increased engine idle speeds.

[0209] A very special advantage of this approach is that market-specific cabin heating performance tests, e.g., specifically geared towards North America, can be passed safely with the vehicle stationary and the engine running, without any additional costs.

[0210] This means that, in particular, the PTC auxiliary heater can be omitted in diesel passenger cars with very cost-effective and, above all, completely identical hardware in Europe and North America.

[0211] It is very advantageous for the inventive procedure in the configuration according to Fig. 1 in particular that with the charge gas deactivation 31b means are available which allow the compression temperatures in the combustion chamber to be raised at the time of fuel injection so that a heat output-oriented shift of the combustion processes becomes possible to a very wide extent, without leading to other problems, in particular to increased oil dilution and / or increased emission of toxic pollutants and / or increased smoke emission or unacceptable noise and / or odor emission.

[0212] Fig. Figure 2 shows the initial system layout for direct comparison. Fig. 1 with a conventional intake-side throttle valve 31sdk and without the exhaust-side throttle valve 31dk according to the invention, as already shown in the Fig. 7 of DE 10 2009 042 745 A1 dated 25.09.2009.

[0213] Here too, one can in principle speak of a low-pressure EGR, since the exhaust gas is extracted on the low-pressure side of the turbine 31tt. However, only the additional installation of an exhaust-side throttle valve 31dk – possibly with the omission of the intake-side throttle valve 31sdk – will provide the full degrees of freedom according to the invention for system improvement, in particular also the potential with regard to the bypass line 11dkby discussed later.

[0214] The system according to Fig. 2 is primarily geared towards the measures of DE 10 2009 042 745 A1 during the warm-up phase until the EGR is first opened and is not initially usable for carrying out all the measures of the present invention.

[0215] As will be described in more detail later, in systems according to Fig. 2 In the case of strong throttling that increases charge exchange loss or fuel consumption, the closing of valve 14 and the partial closing of valve 31sdk result in a reduction of the gas density through the throttle valve 31sdk, and the system is not optimally suited to achieve the widest possible adjustment range for heating-performance-oriented engine control measures and / or high heat transfer in the EGR cooler for cabin heating purposes or in a TEG.

[0216] Therefore, in systems according to Fig. 2. In early warm-up with closed EGR, the temporary procedure according to DE 10 2009 042 745 A1 without throttling at valve 31sdk and with the highest possible boost pressure and simultaneously high exhaust gas mass flow is particularly advantageous.

[0217] The systems according to Fig. The second attempt, currently under consideration, to counteract the cabin heating performance deficit by inducing additional charge exchange losses through the partial closing of the throttle valve 31sdk is – not least for reasons of emissions, oil dilution, heat transfer and dynamics, as well as due to the lack of degrees of freedom regarding the heating performance-oriented combustion process shaping – not nearly as effective and efficient as the induction of charge exchange losses according to the invention with the (free) exhaust-side throttling 31dk according to Fig. 1.

[0218] Fig. 3 shows in comparison to Fig. Figure 1 shows the air and exhaust sides of a very similar system with a slightly higher level of detail on the two gas sides. The charge gas cooling 31k is achieved here via the coolant lines 31kme and 31kma on the water side, and the cooling is deactivated by the water-side valve 31sv. On the fresh air side, the air filter 40 and the air mass sensor 41 are explicitly shown, as well as, on the exhaust side, additional exhaust aftertreatment systems 31NOx and 31H2s downstream of the throttle valve 31dk and the silencer 31SD. The intake-side throttle valve 31sdk is located here in the high-pressure section of the charging branch. For the sake of completeness, the system is shown according to Fig. Figure 3 shows an optional high-pressure EGR branch 11hpegr with a high-pressure EGR flap 14hd. In the heating capacity increase according to the invention with throttling via the flap 31dk and by means of a branch 11lpegr closed by the valve 14, it is generally advantageous to also close the branch 11hpegr, so that surface heat losses and / or fouling in this branch are prevented just as in the branch 11lpegr.

[0219] The systems in Fig. 1 and in Fig. 3 are merely particularly preferred embodiments, without the inventive method being limited to them.

[0220] In particular, the strategy of using heating-performance-oriented engine control measures, such as the inventive throttling of the charge exchange to increase fuel consumption including temporary maximization of the internal / external EGR and raising of the idle speed, only when the engine is idling and the vehicle is simultaneously stationary and / or braked, is of a universal nature.

[0221] For example, with diesel engines, this approach results in a high excess of air when operating with and without external EGR, even at relatively high EGR rates, without road load, sometimes additionally combined with a wide scope for cabin heating-oriented adjustment of the engine control towards increased fuel consumption.

[0222] This applies particularly to exhaust-side throttling, especially in conjunction with high internal or external EGR and also to adjusting the fuel injection towards increased fuel consumption or greater heat dissipation into the coolant.

[0223] It is particularly helpful that, contrary to prevailing expert opinion, a sensible combination of the measures described here makes it relatively easy and inexpensive to meet the market-specific heating system approval tests of individual manufacturers using one and the same hardware, and even to eliminate the need for the electric PTC auxiliary heater currently standard in diesel passenger cars. The same now applies, in part, to passenger cars with highly efficient gasoline engines.

[0224] Furthermore, a very special feature of the methods according to the invention is that they are able to provide the fuel consumption values ​​of the associated patent claims.

[0225] This makes it possible, in particular, to significantly outperform the PTC auxiliary heater in terms of the heating improvement achievable per unit of additional fuel consumption. This has a significant impact on fuel consumption, especially in real-world winter city driving.

[0226] Starting from Fig. 1 shows Fig. 4 a further embodiment of the system improvement according to the invention with a bypass branch 11dkby, which can make better use of the exhaust gas heat when the first EGR control valve 14 is closed / throttled at an EGR cooler 3 and / or an EGR cooler with integrated thermoelectric generator 3teg or only at a thermoelectric generator 3teg.

[0227] For this purpose, the exhaust gas is extracted downstream of the EGR cooler 3(3teg) and fed back into the main exhaust gas mass flow downstream of the second EGR control valve 31dk.

[0228] The in Fig. The extraction point 11by of the bypass branch 11dkby shown is particularly preferably located upstream of the valve 14 and is therefore permeable when the valve 14 is open and closed.

[0229] The position of the valve 31dk and the dimensioning of the flow branch 11dkby in the direction of relatively high pressure loss through an orifice 11drbl and / or particularly low-flow-cross-section and / or long pipe cross-sections of the branch 11dkby are sufficient in this particularly cost-effective embodiment of the inventive method for safe and effective operation with the valve 14 open and closed. In the simplest case, a metal pipe with an inner diameter of approximately 5-15 mm is sufficient to achieve this connection from the system layout into Fig. 1. To achieve an improved effect of the EGR cooler as a heat source for cabin heating purposes and / or to improve the power output of the thermoelectric generator 3teg and / or better drying and earlier activation of the EGR branch 11eff.

[0230] This improves the effectiveness of components 3, 3teg even with strong throttling or reduction of the flow cross-section in branch 11dkby, because even with strong throttling with valve 31dk a noticeable exhaust gas mass flow is still established via components 3, 3teg and especially because the EGR valve 14 can usually be opened much earlier.

[0231] Of course, position 11by can also be integrated into valve 14, or valve 14 can be designed as a 3-way valve so that, depending on its position, it also closes and / or throttles branch 11dkby. An example of such a configuration is shown. Fig. 6.

[0232] In particular, given the above explanations, the structural design of such a 3-way event can certainly allow a certain amount of leakage towards branch 11dkby in many applications and is therefore feasible with comparatively low additional costs.

[0233] This applies, for example, in particular if the throttling by small conductor cross-sections in branch 11dkby and / or the throttle orifice 11drbl is deliberately chosen to be very high, e.g. to make high charge exchange losses adjustable for increasing heating power.

[0234] As already described, the variants according to the invention which operate with conductor cross-sections of branch 11dkby of 5-15 mm inner diameter are of particular interest, since these can be accommodated relatively easily in the very limited engine installation space or thermally insulated.

[0235] Especially with a suitably designed 3-way valve 14, or when illustrating its 3-way valve functionality with two individual valves 14a and 14b, the inventive method is naturally not limited exclusively to such a high degree of throttling or lines with an inner diameter of 5-15 mm. Particularly when there is only a moderate cabin heating power deficit and / or the thermoelectric generator 3teg is to be maximized in its effect with the branch 11eff throttled / closed, it is sometimes more advantageous to avoid excessive throttling in the branch 11dkby.

[0236] For reasons of cost and installation space, in many cases, especially with a high cabin heating power deficit, the described variants with strong throttling in branch 11dkby will prove to be particularly advantageous in the practical implementation of branches 11dkby according to the invention.

[0237] In particular, when there is a significant deficit in cabin heating performance, it is advantageous to design the throttle valve 31dk so that it is relatively tight and can establish exhaust back pressures of 0.2–0.5 bar even at a relatively low exhaust gas flow rate of, for example, 10 g / s through the valve 31dk. Specifically, exhaust back pressures immediately upstream of the valve 31dk of more than 0.5 bar (overpressure relative to the ambient pressure) can be achieved. The resulting increase in fuel consumption is therefore very noticeable and, especially in conjunction with optimized utilization at the EGR cooler, highly effective for cabin heating.

[0238] In cases of extreme cabin heating capacity deficit, it can be particularly advantageous to design the entire system in such a way that exhaust back pressures of 0.3-0.5 bar can be achieved with a fresh air mass flow of 10-20 g / s, or even 1.0-1.5 bar in cases of very extreme additional heating requirements.

[0239] This is particularly helpful when the initial engine warm-up phase needs to be especially short, even at a comparatively low engine speed and / or without increasing the idle speed.

[0240] The reference values ​​for fresh air mass flow (10-20 g / s) and exhaust gas mass flow (10 g / s) mentioned here are based on a 2-liter diesel engine. For other engine displacements, it is particularly advantageous to reduce these values ​​proportionally to the difference in displacement for smaller engines and to increase them for larger engines.

[0241] Without being limited to these figures, it becomes clear in light of these numerical examples that part of the inventive concept is not feasible if the line 11lpegr is not throttled by means of a valve in phases with high exhaust back pressure requirements and / or is already significantly throttled in the basic design by means of a throttling point or small pipe cross-sections.

[0242] Especially in the variants with a permanently open branch 11dkby, it is important that, with branch 11eff open and throttled by valve 31dk, a sufficient EGR mass flow can be set in branch 11eff, and that the EGR cooler (3.3teg) is not thermally overloaded by an excessively high exhaust gas mass flow through branch 11dkby. The dimensioning proposals for the throttling in branch 11dkby specified in the individual sub-claims take this into account.

[0243] Optionally, an independent valve, i.e., one not controllable by the engine control unit, can also close branch 11dkby as soon as a significant increase in exhaust back pressure is desired and / or there is a risk of overload or overheating and / or if it is clear anyway, due to the coolant and / or ambient temperature, that flow through branch 11dkby is not required.

[0244] In particular, simple on / off valves in branch 11dkby with expansion actuator offer a cost-effective solution in the case of purely thermal protection.

[0245] The expansion actuator can, for example, be guided by the ambient temperature and simply close when the ambient temperature is above 20°C, meaning that maximizing cabin heating output is not necessary. More sophisticatedly, it can also be guided by the component temperature or the coolant temperature and close, for example, when this temperature exceeds 70°C or 95°C, thus ensuring that, for instance, no additional heating is required.

[0246] Depending on the design, a wide variety of solutions are conceivable, with and without a thermoelectric generator.

[0247] Even an additional valve that can be controlled by the engine management system is sometimes still justifiable in terms of cost, especially in applications with TEG, particularly when extreme requirements regarding fuel saving are involved.

[0248] Analogous to the above statements regarding Fig. 4 shows Fig. 5 a corresponding adjustment of Fig. 3 with bypass branch 11dkby, sampling point 11by upstream of valve 14, optional throttle orifice 11drbl and EGR cooler 3 and / or TEG bridge. In particular, it is shown here by way of example that the inventive procedure with bypass branch 11dkby makes it possible for the exhaust gas to always flow at least once through the individual exhaust gas treatment systems (31dpf, 31NOx, 31H2S) before it is released into the environment.

[0249] For this purpose, it is particularly advantageous to connect branch 11dkby directly downstream of valve 31dk to the main exhaust branch, i.e., in particular upstream of potential additional exhaust aftertreatment components (31NOx, 31H2S).

[0250] Here too, position 11by is not necessarily located upstream of valve 14, and strong throttling or conductor cross-sections of 5-15 mm of branch 11dkby are only a particularly preferred option for reasons of cost, packaging and increased heating performance.

[0251] In Fig. 4 and Fig. 5 can in particular also be seen that the bypass line 11dkby according to the invention is able to preheat a large area of ​​the EGR system on the exhaust gas side when the valve 14 is closed and in this way to enable earlier opening of the valve 14 without risk to components, in particular also for the turbo compressor 31tv.

[0252] In the case of using a thermoelectric generator in normal operation, i.e. generating electricity from cooling the exhaust gas while transferring heat to the coolant, it is particularly advantageous if, in the event of a cabin heating deficit, the electrical circuit is reversed to heat the exhaust gas while simultaneously increasing the cabin heating output.

[0253] Various configurations and control options for the two valves 14 and 31dk have already been described. It is particularly simple in terms of control and also particularly cost-effective if the first EGR control valve 14 is a simple on / off valve without intermediate positions and the control of the recirculated exhaust gas quantity by the engine control unit 20 is carried out by the second EGR control valve 31dk in the main exhaust manifold.

[0254] Further cost minimization and simplification result in particular if the first EGR control valve 14 is arranged downstream of the branch position 11by, so that when the first EGR control valve 14 is closed, a permanent but geometrically precisely defined leakage or target exhaust gas flow, which can be changed by means of the valve 31dk, is present in the bypass line 11dkby.

[0255] Of course, sufficient dimensioning of the pressure losses in branch 11dkby must be ensured, in combination with the pressure loss of the valve 31dk in the open state and in combination with the cooling reserve of the vehicle radiator 8 and the EGR cooler (3, 3teg).

[0256] Only moderate additional requirements for the vehicle radiator 8 and the EGR cooler (3, 3teg) arise in particular if the flow-determining flow cross-sections and line lengths of the branch 11dkby are dimensioned so that, with the first EGR control valve 14 fully open, the leakage exhaust gas mass flow in the bypass line 11dbky is less than 30% of the EGR mass flow conveyed to the fresh air line 10f.

[0257] For reasons of installation space, it is particularly advantageous in many applications if, irrespective of the design of the valve 14 and irrespective of the maximum permissible leakage in the branch 11dkby, the bypass line 11dkby has pipe sections with a total length of at least 200 mm and that in this area there is a mean flow cross-section of less than 190 mm. 2 (= 0.5 * (3.14 * 22 2 ) / 4) mm 2). A certain throttling effect is deliberately accepted here in favor of ease of installation.

[0258] In some applications, it is particularly advantageous if the bypass line 11dkby has at least one throttle point 11drbl with a minimum flow cross-section that is less than 50% of the flow cross-section of the fully open first EGR control valve 14, or any other throttle point with a comparable throttling effect. This ensures, in particular, that the EGR control valve has sufficient clearance to set the appropriate EGR rates and that the EGR cooler is not overloaded by the exhaust gas flow in branch 11dkby.

[0259] An approximately analogous effect can also be achieved if the bypass line 11dkby has at least one throttling point, in particular a flow orifice 11drbl, with a narrowest flow cross-section of less than 144 mm. 2 exhibits.

[0260] In particular, it is advantageous if the position and functions of the extraction point 11by of the bypass line 11dkby are integrated into the first EGR control valve 14. This leads to space savings and optimal preheating of the EGR branch, including the valve 14.

[0261] For special requirements regarding controllability or overheating protection, it is particularly advantageous if the position of the extraction point 11by of the bypass line 11dkby is integrated into the first EGR control valve 14, and this valve, as a multi-way valve, takes over the control / shut-off of the bypass branch 11dkby in addition to EGR control via the engine control unit. In this way, the operating range of the EGR cooler or TEG can be extended towards higher temperatures and lower exhaust backpressures. In particular, the throttling in the bypass branch 11dkby can then be significantly smaller or even largely eliminated when the bypass branch 11dkby is fully open, especially if a small-diameter bypass line is not required for engine-specific installation space reasons.

[0262] Even though some aspects of the inventive method can also be used on engines with high-pressure EGR, the inventive method is particularly attractive in many cases when the inventive measures are used as a package of measures and especially on engines with low-pressure EGR.

[0263] Low-pressure EGR systems, e.g. according to Fig. 1 and Fig. 3-6 with exhaust-side EGR throttle 31dk, offer the very special advantage that, in operation with exhaust gas recirculation, due to the inherently lower throttling on the fresh air side, there is on average a higher fresh air and exhaust pressure in the entire system than with HD systems, i.e. a higher gas-side pressure upstream of the engine, downstream of the engine and also within the engine.

[0264] This promotes high EGR mass flows and thus – given the required fresh air or oxygen for combustion – high heat transfer rates at the engine and the EGR cooler. This is due – even with charge air cooling deactivated – primarily to the increased density of the recirculated exhaust gas and the improved efficiency of the turbocharger during low-pressure EGR according to [relevant standard / regulation]. Fig. 1 and Fig. 3-6.

[0265] With the same target oxygen content of the mixture of fresh air and recirculated exhaust gas in the combustion chamber of the engine, a higher EGR mass flow is ultimately possible, as well as a wider adjustment range for heating performance-oriented engine control measures, such as the shifting of the injection timing.

[0266] In addition, there is the possibility of setting the EGR rate so high that combustion, even without changing the injection, proceeds significantly slower and with a lower efficiency relative to operation without a heating power deficit.

[0267] Therefore, even without the bypass branch 11dkby, a significantly improved cabin heating performance is achievable due to the higher EGR rates compared to HD-EGR and due to a higher heat input at the EGR cooler and within the engine.

[0268] Faster engine warm-up ultimately also improves the effectiveness of a thermoelectric generator, whereby, without a heating power deficit, the EGR is naturally preferentially adjusted towards optimal combustion.

[0269] It is particularly helpful that the inventive preheating of the coolant and / or the EGR system up to valve 14 by means of throttling via valve 31dk and / or other engine control measures makes it possible to open valve 14 relatively early and thus initiate EGR. With the initiation of EGR, the throttling with valve 31dk can then also be set to relatively small values.

[0270] In the examples shown here, it is particularly important to note that the DPF with integrated oxidation catalyst 31dpf ensures that only relatively clean exhaust gas flows through the EGR cooler and / or the thermoelectric generator.

[0271] Contrary to the prevailing view in the field – which currently clearly favors the extraction of exhaust gas upstream of turbine 31tt for the potential arrangement of a TEG in the EGR branch, i.e., high-pressure EGR, in order to maximize the effectiveness of the TEG by means of the highest possible exhaust gas inlet temperatures to the TEG – the synergies according to the invention show that it is significantly more advantageous to combine a TEG with a low-pressure EGR. The higher EGR mass flows and the exothermic oxidation of unburned exhaust gas components in the DPF with oxidation catalyst ultimately lead, even without branch 11dkby, to a comparable or better heat input in the EGR cooler and / or TEG in a low-pressure EGR system compared to a corresponding situation with high-pressure EGR.

[0272] In particular, in conjunction with the deactivation of the charge gas cooler 31k, this results in several advantages, because on the one hand the charged fresh air, which is heated at the turbo compressor 31tv, is not cooled, and on the other hand the recirculated exhaust gas is not cooled at the charge gas cooler 31dk.

[0273] For example, the design according to Fig. 1. When the charge gas cooler 31k is deactivated, the possibility of high boost pressure with additional heating of the recirculated exhaust gas at the turbo compressor 31tv.

[0274] However, at a somewhat lower level, even with low-pressure EGR, the following results are obtained according to... Fig. 2 analogous advantages due to a - albeit in comparison to Fig. 1 lower - increase in boost pressure relative to a comparable high-pressure EGR and due to the heating of the recirculated exhaust gas at the turbo compressor 31tv.

[0275] Even if the intake-side throttle 31sdk is located downstream of the turbo compressor 31tv, a low-pressure EGR with the introduction of the recirculated exhaust gas upstream of the charge air cooler 31k and the deactivation device (31b, 31sv) of the charge air cooler still offers certain advantages with regard to the recirculated exhaust gas mass and the boost pressure or charge temperature in the engine.

[0276] Ultimately, the described low-pressure EGR systems, especially the systems according to Fig. 1-6, for a TEG and / or for improved cabin heating with the strategies according to the invention, advantageously controllable by the engine control unit, as long as an intercooler deactivation device (31b, 31sv) is available.

[0277] Even though a low-pressure EGR with an exhaust-side throttle valve 31dk initially appears to be somewhat more expensive than one with an intake-side throttle valve 31sdk, e.g. according to Fig. 2, when considering all synergies according to the invention, this is usually ultimately the most advantageous.

[0278] Particularly in connection with the separation of potential soot particles in the DPF, the above considerations clearly show that the low-pressure system is significantly advantageous for EGR-TEGs and / or cabin heating performance improvements compared to high-pressure EGR.

[0279] This applies in particular to the long-term effectiveness with increased switching frequency of the EGR cooler and / or even continuous operation of parts of the EGR branch, which results in part from the use of the options with the bypass branch 11dkby.

[0280] In conjunction with the additional bypass branch 11dkby, not only is exhaust gas heat recovered before activation of the EGR, but activation of the EGR is also made possible earlier during warm-up. In particular, depending on the configuration of the hardware according to the invention, a certain proportion of the energy contained in the exhaust gas can thus be used for cabin heating purposes and / or thermoelectric energy generation, both with and without opening the EGR valve 14.

[0281] In particular, the additional bypass branch 11dkby allows for significantly better use of fuel energy, which may be used to increase cabin heating performance by means of heating-performance-oriented engine control measures, compared to engines currently found in mass-produced passenger cars.

[0282] In this respect, the response behavior of the turbocharger and the rapid availability of an increased amount of fresh gas due to the increased system pressure ia are particularly favorable than with a high-pressure EGR, which usually uses a throttle 31sdk in the intake system to achieve sufficiently high EGR rates, or in which the recirculated exhaust gas mass flow at the turbine 31tt is naturally absent.

[0283] In particular, the additional measures according to the invention, which temporarily deactivate the charge gas cooler 31k at high EGR rate and high cabin heating power requirement or during engine warm-up, make a significant additional contribution.

[0284] Furthermore, the charge gas cooler 31k ensures – particularly in applications with a permanently open branch 11dkby or with a deliberately high volume flow in branch 11dkby in favor of the TEG – that sufficient charge gas cooling still takes place even with a relatively high total mass flow in branch 11eff alone or in both branches 11eff and 11dkby.

[0285] Against this background, it is particularly advantageous in a device for operating a cooling and heating circuit for motor vehicles with a turbocharged internal combustion engine 1 (31tt / 31tv) and charge gas cooling 31k, with low-pressure exhaust gas recirculation with a first EGR control valve 14 and with a low-pressure EGR branch 11(11Ipegr), which temporarily mixes exhaust gas into the fresh air from the fresh air path 10f in the main exhaust gas flow 10ft via the low-pressure EGR path 11(11Ipegr) upstream of the charge gas cooler 31k, while partially / completely closing a second EGR control valve 31dk, if this • in the low-pressure EGR path 11(11Ipegr) has a coolant-side exhaust gas recirculation cooler 3(3teg) with an integrated and / or a separate coolant-cooled thermoelectric generator for generating electricity from the exhaust gas and • a position of the first EGR control valve 14 between the EGR cooler outlet and the mixing point of the recirculated exhaust gas to the fresh air branch 10f and • an exhaust gas bypass line 11dkby connected to the low-pressure EGR branch 11(11Ipegr) at the first EGR control valve 14 or further upstream, which directs exhaust gas flowing through the exhaust gas recirculation cooler 3(3teg) at least temporarily, in particular permanently by using throttling measures in the flow branch 11dkby, to a position downstream of the second EGR control valve 31dk in the main exhaust gas flow 10ft and • in particular, that the function of the thermoelectric generator for cabin heating purposes is switched from the standard operating mode of power generation / exhaust cooling / coolant heating to the electrically inverse operating mode of power consumption / exhaust heating / coolant heating and • in particular, that the heating heat exchanger 4 is arranged on the coolant side downstream of the EGR cooler 3(3teg).

[0286] The particularly preferred application of this combination of measures on an engine with low-pressure EGR, e.g. according to Fig. 4-6 is particularly advantageous, among other reasons, because the 31dk throttle valve is required anyway for optimized operation in the legally mandated exhaust gas test, i.e., without heat extraction and without AC operation, and is therefore available at no additional cost.

[0287] Furthermore, the measures and effects described above for maximizing the EGR rate and the heat transferred at the EGR cooler or TEG are fully effective because the pressure level in the intake tract remains relatively high even at high EGR rates. This, in turn, is a result of the specific low-pressure arrangement with the previously described characteristic that all exhaust gas passes through the turbine 31tt of the turbocharger and the recirculated exhaust gas is introduced before the compressor 31tv, as well as the inventive effect of the throttle valve 31dk, i.e., the intake-side / charge-gas-side throttle valve 31sdk, if present, is open. In addition, the extremely beneficial interaction of the inventive deactivation of the charge-gas cooler 31k ensures significantly improved energy utilization in many operating situations, particularly for cabin heating and / or the TEG, but also for engine warm-up itself.

[0288] The advantages of the inventive procedure with a bypass branch 11dkby and a throttling device 31dk in the main exhaust gas stream are so high that it is also cost-effective if a separate and independent valve in the bypass branch 11dkby, in particular a thermostatic valve, which is not actuated by the engine control 20, ensures that the branch 11dkby is closed / throttled in case of potential overheating of the components or the coolant.

[0289] The same applies, at least in part, if the engine has a bypass branch 11dbky for using the EGR cooler 3(3teg) and if a throttling of the exhaust mass flow in the bypass branch 11dbky, which is particularly advantageous for cabin heating purposes, is omitted. In this way, the first EGR control valve 14 can be a three-way valve located at position 11by, deactivating the EGR during warm-up while still utilizing the TEG and / or EGR cooler and simultaneously drying it, thus enabling, for example, faster activation of the EGR.

[0290] In particular, such a valve, when partially heated, can divide the exhaust gas between branches 11ef and 11dkby and / or close one or both branches in case of overheating.

[0291] Even more refined control options arise in particular if, instead of a three-way valve 14, a third EGR control valve 14b, which can be controlled by the engine control unit 20, opens and closes the bypass branch 11dkby as required, in addition to the first EGR control valve 14(14a) and the second EGR control valve 31dk.

[0292] In all applications according to the invention with a second EGR control valve 31dk in the main exhaust gas stream and a bypass line 11dkby, it is generally particularly advantageous, or even essential in some cases, to proceed such that the second EGR control valve 31dk is arranged downstream of an exhaust aftertreatment component, in particular downstream of a catalyst and / or a particulate filter 31dpf, and a bypass line 11dkby branches off exhaust gas from the exhaust gas recirculation branch 11(11Ipegr) downstream of an EGR cooler 3(3teg) and feeds it into the main exhaust gas mass flow 10ft downstream of the second EGR control valve 31dk and upstream of the second EGR control valve 31dk, in particular upstream of exhaust aftertreatment components for NOx (31NOx), sulfur (31H2S) or for noise reduction (31SD). This ensures the full effectiveness of the exhaust gas purification.

[0293] In special cases, and even in some cases where the risk of contamination is low, it is advantageous if the second EGR control valve 31dk is arranged upstream of an exhaust aftertreatment component, in particular upstream of a catalyst and / or a particulate filter 31dpf, in the exhaust stream, and a bypass line 11dkby branches off from the exhaust gas recirculation branch 11(11Ipegr) downstream of an EGR cooler 3(3teg) and feeds into the main exhaust gas mass flow 10ft downstream of the second EGR control valve 31dk and upstream of the second EGR control valve 31dk, in particular upstream of exhaust aftertreatment components for soot and / or CO and HC (31dpf), NOx (31NOx), sulfur (31H2S) or for noise reduction (31SD). In this arrangement, the temperature level is somewhat higher, especially when the exhaust aftertreatment has low exothermicity.

[0294] In particular, it is also advantageously possible to adapt the concept according to the invention so that, instead of a low-pressure EGR, any type of EGR is used, in particular a high-pressure EGR with exhaust gas extraction upstream of a turbine 31tt of a turbocharger and / or exhaust gas injection into the combustion fresh air mass flow 10f downstream of a charge gas cooler 31k, and that, in order to improve the cabin heating effect and / or the effectiveness / utilization of a thermoelectric generator in the EGR branch (3, 3teg), in addition to a first EGR control valve 14 which is continuously adjustable by the engine control unit for EGR control, an additional valve 31dk in the main exhaust gas flow 10ft takes over the function of the EGR control valve 31dk. The charge gas-side valve 31sdk, typical of high-pressure EGR, can optionally be fully opened and / or participate in the EGR control.

[0295] The valve 31dk, as used according to the invention in the main exhaust stream 10ft, enables, with a sufficiently tight design, a significant contribution to overcoming high cabin heating performance deficits, particularly when the branch 11dkby according to the invention is used and is capable of exerting a sufficient throttling effect. In many applications, it is sufficient to meet the cabin heating release tests if, depending on the vehicle, an exhaust back pressure of 0.2–0.5 bar can be set at engine speeds of approximately 1200–1600 rpm with both valve 14 and valve 31dk closed. In extreme cases, however, the pressure ratio in branch 11dkby and at the leakage stream through valve 31dk can exceed the so-called critical pressure ratio; the two exhaust flow rates are then limited by the speed of sound.

[0296] However, it is generally sufficient and, for reasons of fuel consumption and possibly also noise, particularly advantageous if, in a turbocharged internal combustion engine 1 with external exhaust gas recirculation 11 (11lpegr) and a cabin heater heat exchanger 4 through which liquid coolant flows, an EGR cooler 3 and / or a thermoelectric generator (TEG) in the EGR branch 3teg, a throttle valve 31dk in the main exhaust stream 10ft, at least temporarily, establishes an exhaust pressure immediately upstream of the throttle valve 31dk relative to the environment of at least 0.2 bar, particularly preferably a range of 0.2–0.4 bar, and a bypass branch 11dkby diverts exhaust gas flowing through the EGR cooler / TEG (3, 3teg) downstream of the throttle valve 31dk into the main exhaust stream when there is a heating power deficit. feeds in at 10ft.This also represents a particularly good ratio between the increased fuel consumption due to the increased exhaust back pressure and the component requirements, and in particular provides a usable exhaust volume flow in branch 11dkby as well as a small installation volume for this branch.

[0297] In this context, it is particularly important to note with state-of-the-art diesel engines that, for example, with valve 14 permanently closed and branch 11dkby permanently open, the sole use of an EGR cooler 3 as an exhaust gas heat exchanger for the main exhaust gas flow generally cannot provide a sufficient additional contribution to cabin heating to eliminate the need for the PTC auxiliary heater. Therefore, according to the invention, exhaust gas-side throttling and / or at least one other additional measure for increasing fuel consumption in a way that is geared towards heating output is provided.

[0298] A system with bypass line 11dkby, which is particularly advantageous in terms of small installation space according to the invention, is characterized in particular by the fact that the bypass line 11dkby has a mean flow cross-section over a length of at least 200 mm, and preferably even over 300-700 mm, which corresponds to a pipe with an inner diameter of less than 15 mm, and in particular less than 5-12 mm.

[0299] The pressure losses, which at first glance appear to be far too high, are quickly put into perspective, especially when the above statements regarding the increase in cabin heating performance and / or EGR rate maximization and / or heat input limitation at the EGR cooler 3(3teg) are taken into account.

[0300] In order not to disadvantage the exhaust aftertreatment, it is particularly advantageous if no exhaust aftertreatment component (31dpf, 31NOx, 31H2S) is arranged between the extraction point for the recirculated exhaust gas from the main exhaust branch and the reintroduction point of the bypass branch 11dkby into the main exhaust branch.

[0301] Such a procedure is not entirely easy to implement with regard to the installation space and is often only made possible by the particularly preferred approach with very small conductor cross-sections of branch 11dkby.

[0302] In the described applications with a thermoelectric generator in the EGR branch, but also in any vehicle applications where a thermoelectric generator converts waste heat, in particular waste heat from the exhaust gas or from drive components or from its subcomponents, into electricity and is cooled with the same coolant as the cabin heating heat exchanger 4 is heated, further cabin heating performance-oriented degrees of freedom arise in particular, which consist of controlling the thermoelectric generator electrically for heat generation in a modified way and thus increasing the coolant temperature and the cabin heating performance.

[0303] In the simplest case, this statement relates to a device for cooling a vehicle drive and / or its auxiliary components with liquid coolant and for heating the passenger compartment by means of a heating heat exchanger 4 through which this liquid coolant flows, with a thermoelectric generator which is also cooled by the liquid coolant of the vehicle drive and thereby converts waste heat into electricity via a thermoelectric effect, in particular the Seebeck effect, in that heat from a heat source, in particular heat from the exhaust gas of a combustion process, is transferred into the liquid coolant and heats it.

[0304] As a first step, it helps if the TEG is electrically disconnected and / or short-circuited from the vehicle battery to increase the cabin heating effect.

[0305] Disconnecting the electrical system at least reduces heat extraction from the coolant, but in internal combustion engines it also increases the engine load due to the reduced strain on the electrical system and alternator. While a 200 W reduction in electrical power may seem relatively small, it is noticeable across the efficiency chain of the engine and alternator.

[0306] Furthermore, short-circuiting the TEG has the additional effect that the current from the TEG heats up the TEG and the coolant even more, and also heats the TEG at its own internal resistance. Since the short-circuit current ia depends primarily on the internal resistance of the TEG, it is particularly higher than in the case of conventional operation as a TEG.

[0307] In the case of a conventional TEG, such a short circuit is relatively straightforward. Of course, the higher current must be taken into account with appropriate local power line cross-sections, fuses, and switches.

[0308] The heating effect is further improved if the TEG is electrically powered by the vehicle battery, at least temporarily in the opposite direction, to increase the cabin heating effect, and in particular if an alternating current-like supply with reversal of the electrical flow direction takes place.

[0309] In heating mode for cabin heating purposes and / or for evaporating / burning off exhaust-side surface contaminants, it is particularly advantageous for thermoelectric generators composed of many individual cells if individual cells or groups of individual cells are switched in such a way that a reduced internal resistance results compared to normal operation. This allows the electrical energy dissipated in the electric generator for heating purposes to be increased, and in particular the internal current to be significantly increased to maximize heat dissipation at the remaining internal resistance.

[0310] The external power lines, switching and safety elements of the TEG are preferably designed in such a way that they can safely handle the increased currents during heating operation and / or are only operated for a limited time.

[0311] For a thermal energy generator (TEG) designed for 200 W electrical power output in the EGR branch of a diesel engine, a significantly higher current can flow through the TEG in heating mode, even with a conventional vehicle battery with a target charging voltage of approximately 14.5 V. This allows the TEG to operate with a much higher current instead of approximately 13.9 A (= 200 W / 14.4 V), thus considerably increasing the heating power output at the internal resistance. However, every increase in current initially translates directly into more heat at the TEG itself. In the case of power being drawn from the vehicle battery of a combustion engine vehicle, this simultaneously increases the engine load and thus the engine's waste heat.

[0312] Against this background, TEGs are of particular interest in which a short-circuit current or an RMS value of the current is realized that is more than 1.5 times, in particular more than 2-5 times, as the rated current in operation as a thermoelectric generator to relieve the on-board voltage network.

[0313] Reversing the electrical flow direction, switching off the electrical circuit, or short-circuiting the thermoelectric generator can be used in auxiliary heating mode not only to strongly heat the exhaust side of a thermoelectric generator and thus indirectly also the coolant side, but also, if necessary, to clean the exhaust side of deposits.

[0314] The following are some particularly important reasons why the application according to the invention, including the transfer and adaptation of the intellectual property of DE 10 2009 042 745 A1, is particularly suitable for turbo engines with low-pressure EGR systems, and why such engines are particularly preferred with regard to the low-pressure EGR, similar to the one in Fig. 1- Fig. 6 are set up.

[0315] Fig. 1- Fig. Figure 6 shows all low-pressure EGR systems for turbo engines with EGR extraction downstream of the turbine 31tt of the turbocharger and with the introduction of the recirculated exhaust gas upstream of the charge gas cooler 31k.

[0316] Compared to a high-pressure EGR system with EGR extraction upstream of turbine 31tt and EGR injection downstream of the charge air cooler 31k, this provides a particularly good cooling effect for the charge air, even at high EGR rates. Simultaneously, the entire exhaust gas mass flow passes through turbine 31tt and is thus available to drive the compressor 31tv. In the legally mandated emissions test, this ultimately results in lower NOx values ​​due to high charge density and low charge temperature, combined with relatively high EGR rates. Therefore, low-pressure EGR systems are of particular interest for future engines.

[0317] At the same time, in Fig. 1- Fig. 6 a deactivation device (31b or 31sv) for the temporary deactivation of the charge gas cooler 31k.

[0318] This deactivation device (31b, 31sv), which is particularly preferably also directly controllable by the engine control unit 20, ensures that the exhaust gas, which is raised to higher temperatures e.g. by means of the heating power-oriented fuel injection times and / or the throttling via the throttle valve 31dk, is not cooled down again to a considerable extent by the charge gas cooler 31k.

[0319] In return, the deactivation device (31b, 31sv) enables, if necessary, the rapid switching to full cooling capacity for the charge gas and, in particular, the option according to the invention to allow a certain leakage and / or a permanently open overflow in a branch 11dkby if the EGR cooler (3, 3teg) and the charge gas cooler 31k are sufficiently dimensioned.

[0320] Since the EGR cannot remain permanently closed during warm-up for emission reasons or legal reasons, it is generally not possible to send all exhaust gas through the EGR cooler or TEG via branch 11dkby for an extended period of time.

[0321] This, along with the mandatory limitation of the maximum exhaust gas temperature in branch 11eff, leads to the surprising conclusion that it is generally not very cost-efficient to design the entire branch 11dkby to have a low pressure drop and a high control range for the exhaust gas mass flow in order to recover as much electrical energy as possible at the TEG during warm-up and warm-up operation and / or to improve cabin heating performance cost-effectively. This is especially true for applications that very often already operate with relatively high EGR mass flows.

[0322] The thermodynamically most favorable solution exists at lower engine partial loads, with engine speeds of, for example, less than 1600 rpm, in order to, for example, Fig. 6 to optimally utilize the exhaust gas heat for engine warm-up and / or cabin heating and / or the TEG, seemingly at first glance by making the entire branch 11dkby including the EGR cooler (3(3teg) and the valve 14 as pressure loss as possible and by supplying the two branches 11lpegr and 11dkby during warm-up in such a way that initially all exhaust gas flows through branch 11dkby and then gradually the EGR branch 11Ipegr is opened and branch 11dkby is partially or completely closed.

[0323] While this approach is certainly feasible in principle, it often leads to space constraints and relatively high component costs, including additional costs for heat protection. Furthermore, in cases of significant cabin heating power deficit, a certain increase in exhaust back pressure is often desirable, at least during the first few minutes of warm-up, which may in turn make valve 14 even more complex.

[0324] In addition, there is the fact, already described above, that the EGR must be activated during the warm-up phase anyway for emission reasons or for legal reasons, so that not an unlimited amount of exhaust gas may flow through the EGR cooler in order to avoid the risk of thermal overload of the EGR cooler, the cooling system or the turbo compressor.

[0325] Against this overall background and against the specific background that the EGR cooler 3, in its function as an EGR cooler, can only cool or utilize a limited amount of exhaust gas for emission reasons and also in its cooling function to protect the turbo compressor, the significantly simpler and cheaper variants according to the invention with reduced flow cross-sections and exhaust pipe diameters in branch 11dkby are highly attractive.

[0326] The solution with sampling point 11by, e.g. in Fig. 5, which in extreme cases reduces the effort for the EGR valve 14 to a simple on / off valve, is to be assessed in a very similar way.

[0327] In this context, it is of course very important to cool the charge gas only with the 31k charge gas cooler if this is advantageous from the engine's perspective and in the overall consideration of all systems. This applies particularly to engine warm-up with and without heating / AC operation, but also especially to operating situations with a cabin heating deficit and, in particular, to the most efficient possible use of an EGR TEG.

[0328] Against this background, with and without cabin heating performance deficits, there are a number of partial load driving situations where the targeted deactivation of the charge gas cooler 31k brings synergistic advantages that cannot be used on diesel vehicles so far because the charge gas deactivation 31b or 31sv is not available or is not optimally controlled.

[0329] For rapid cabin heating with heating-performance-oriented engine control measures, the deactivation of the charge gas cooler 31k is also an extremely helpful means that, via the increased charge gas temperatures, a fuel consumption-increasing shift in fuel injection / ignition is possible.

[0330] In particular, even after EGR activation – especially in cases of very high heating power deficit – it is advantageous if the fuel-consumption-increasing combustion irregularity is optionally supported by shifting the injection timing / ignition and / or by slight throttling with valve 31dk. Depending on the valve design, it is particularly advantageous if, in addition to valve 31dk, valve 14 is also set to an intermediate throttling position.

[0331] ND-EGR systems according to Fig. 1- Fig. 6 have the very special advantage, due to the specific extraction of the recirculated exhaust gas downstream of the turbine 31tt of the turbocharger, that compared to today's turbo engines with high-pressure EGR a significantly larger range of the recirculated EGR mass flow can be set.

[0332] This is partly because the total gas mass flow passing through the engine also passes through the turbocharger, and this significantly promotes boost pressure build-up. In typical high-pressure EGR systems of modern production engines, exhaust gas is extracted upstream of the turbine, meaning this exhaust gas portion is missing from the turbine. Conversely, a higher boost pressure increases the available range for the EGR rate, partly because a sufficient number of oxygen atoms per cylinder charge are still present even with a higher exhaust gas fraction.

[0333] It is particularly advantageous with regard to boost pressure build-up and with regard to particularly high maximum achievable EGR values ​​if the throttle device 31dk for generating the pressure differential in the EGR branch is arranged in the exhaust stream, as in Fig. 1 and Fig. 3 - 6.

[0334] Compared to Fig. 2 offer Fig. 1 and Fig. 3 - 6 the adjustment range for even more extreme EGR rates, among other things because the air density in the fresh air branch is not reduced or only very slightly reduced and the charge air at the turbo compressor inlet, composed of the recirculated exhaust gas and the fresh air, is also at a pressure level close to ambient pressure even at high EGR rates.

[0335] The exhaust backpressure required to adjust the desired EGR is provided by throttle valve 31dk. This results in only a moderately increased pressure in the exhaust system, especially with a relatively low fresh air mass flow and a wide-open valve 14. Consequently, the turbocharger achieves good boost pressure build-up even with relatively small amounts of fresh air due to the high volume of gas flowing through the engine and turbocharger. In other words, the lack of throttling at valve 31sdk increases the overall system pressure in all areas upstream of throttle valve 31dk, leading to higher partial-load heat input for the engine structure, coolant, and EGR cooler / TEG.

[0336] Against this background, the orders according to Fig. 1 and Fig. 3 - 6 with low-pressure EGR and throttle valve 31dk in the exhaust system is of particular advantage for improving cabin heating performance and the use of a TEG in the EGR branch.

[0337] In addition, the well-known high potential of low-pressure EGR systems with EGR inlet upstream of the turbo compressor 31tv, in supplying the engine with a very cold mixture of fresh gas and exhaust gas, in combination with the activation / deactivation of the cooling effect of the charge gas cooler (31k, 31sv) according to the invention, and in particular with the arrangement of an EGR throttle valve 31dk in the exhaust stream, provides, according to the invention – especially in the lower engine partial load – a significantly increased range for operating high EGR rates and simultaneously also for routing a non-recirculated partial exhaust gas flow through the EGR cooler without encountering problems with pollutant emissions. This is of far-reaching importance, not least for cabin heating performance and the optimal utilization of an EGR TEG.

[0338] With and without EGR-TEG, there are therefore numerous very good reasons to design the charge air and exhaust systems according to one of the configurations according to [reference to relevant information] in turbocharged engines with integrated EGR-TEG and / or in turbocharged engines with cabin heating performance deficit. Fig. 1 and Fig. 3 - 6 and to execute the optimizations according to the invention in the control of the individual components in a motor-specific or vehicle-specific manner. As already mentioned, an HD branch 11 hpegr is to be considered optional in this context and may even be omitted depending on the application, in particular because the procedures according to the invention generally prefer other methods than an external HD-EGR in the first 3-5 minutes anyway.

[0339] Compared to an optimal configuration for the legally mandated fuel consumption or emissions test, low-pressure EGR systems often suffice. Fig. 1 and Fig. 3 - 6 already achieve their goal with a cost-neutral solution and often saves, for example, the costs for an electric PTC auxiliary heater and / or improves cabin heating performance and / or improves the actual fuel consumption for the vehicle user.

[0340] Nevertheless, it should be noted in conclusion that a whole series of the improvement approaches according to the invention, as defined in the independent and / or associated patent claims, can of course also be applied to systems other than those in [the original text]. Fig. 1 and Fig. 3 - 6 can be used.

[0341] This applies in particular to turbocharged engines in which no low-pressure EGR is used, but a high-pressure EGR with charge gas-side throttle 31sdk and an additional throttle valve 31dk in the exhaust stream is arranged, or if, instead of the additional throttle valve 31dk in the exhaust stream, an adjustment device controlled by the engine control 20 for adjusting the turbine geometry of a turbocharger provides the pressure differential for flow through the bypass branch 11dkby.

[0342] The same applies in particular to the use of a TEG for heating the coolant for cabin heating and / or cleaning exhaust-side TEG surfaces of combustion exhaust gas by short-circuiting and / or reversing the electrical current direction.

[0343] The methods and devices according to the invention are particularly suitable for eliminating the need for expensive external auxiliary heaters, especially air-side PTC auxiliary heaters, in all engine variants of a vehicle platform. This means, in particular, that the installation space for an air-side PTC auxiliary heater no longer needs to be provided in the heating / air conditioning unit due to individual engine variants with a heating power deficit, nor does the associated electrical peripheral equipment need to be provided. This simplifies the entire vehicle series.

[0344] Therefore, the inventive method is particularly advantageous when it is assigned to a vehicle with an internal combustion engine, in particular with a low-pressure EGR system, which does not provide an external auxiliary heater for cabin heating purposes in any engine configuration, in particular no electric PTC auxiliary heater for heating the cabin air.

[0345] The additional measures described for increasing heating performance on the cooling circuit and / or heating circuit side are particularly preferred, as they are based on a temporary reduction of the total coolant flow rate through the combustion engine 1 and / or the heating branch 4a and / or on the use of high-performance cabin heat exchangers operated at a point close to thermal saturation. This helps, in particular, to keep the increased fuel consumption within limits.

[0346] The achievement of thermal saturation depends on the coolant and air mass flow through the heating heat exchanger 4, whereby the advantages according to the invention can be used particularly in the near range of saturation and even more so at 100% saturation.

[0347] Therefore, it is particularly advantageous if a heat exchange rate / heat utilization rate of at least 90% is defined at the heating heat exchanger 4 with a coolant temperature of +10°C and an ambient temperature of -20°C, and with the heating heat exchanger air mass flow automatically applied according to an automatic climate control system.

[0348] This heat exchange rate / heat utilization rate is particularly advantageous for all heating coolant volume flows at or at least from a minimum engine speed of, for example, 1200-1500 rpm.

[0349] With this definition of a heat exchange rate (= heat utilization rate) formed from the coolant supply temperature and the air inlet and outlet temperatures at the heating heat exchanger in the known manner, many vehicles with modern automatic climate control and initially still relatively cold coolant for a longer period of time - and thus partly still cold blockage on the air side - can be significantly improved.

[0350] In particularly efficient high-performance heating heat exchangers, this characteristic range is also extended, especially towards higher cabin air mass flows.

[0351] The engine control measures according to the invention for increasing cabin heating performance are generally suitable for eliminating the need for the air-side PTC auxiliary heater, which is considered the technology standard, while simultaneously improving pollutant emissions and fuel consumption. This makes these measures particularly immune to the potential accusation of violating legal requirements as so-called "emission defeat devices" because they might produce an unexpected deterioration in emissions outside of the legally mandated emissions test.

[0352] The improvement according to the invention is particularly efficient only when the most effective possible charge air cooler deactivation is available. Charge air-side deactivation is especially effective here, as it enables low thermal inertia and low heat losses. Therefore, charge air cooler deactivation (31b) consisting of a charge air-side charge air cooler bypass branch 10b, switchable by the engine control unit 20, is particularly preferred.

[0353] Since the charge air cooler deactivation according to the invention is primarily used in partial load operation and when the engine is still relatively cold, it is particularly advantageous if the charge air cooler bypass branch 10b has a mean flow cross-section that is less than 50% of the mean flow cross-section of the charge air lines (10a, 10ab, 12) connected to the charge air cooler and / or, in the case of engines with a displacement of 1.5–2.5 liters, has a mean inner diameter of less than 25 mm instead of the typical 50–60 mm. This reduces surface heat losses and component costs and, in particular, simplifies the installation space situation.

[0354] To facilitate understanding of some particularly important aspects of the inventive method, including DE 10 2009 042 745 A1, the following section will again discuss, by way of example and in particular with rough numerical guidelines, particularly preferred adjustable states for improving cabin heating performance, even at the cost of increased fuel consumption. For the purpose of discussing potential inventive settings, the system according to [reference to system] will be used as an example. Fig. 1.

[0355] The basis is again a drive at 50 km / h with a typical 2 I turbodiesel engine at an engine speed of, for example, 1500 rpm, with engine setting parameters such as those found in vehicles of the Golf class from many manufacturers.

[0356] As calculated above, such an engine, with an air density of 1.2 kg / m3 and a displacement of 2.0 l, has a reference fresh air mass flow of m L,ref= ((1500 / 2) / 60) * 2.0 / 1000 * 1.2) = 0.030 kg / s.

[0357] During a cold start at low ambient temperatures, the EGR is usually initially deactivated, and the effective fresh air mass flow rate, without any engine control measures focused on heating performance, is of the same order of magnitude, i.e., around 30 g / s. This is due, not least, to the fact that the turbocharger can only build up a comparatively low boost pressure and / or is not set to the maximum possible boost pressure, among other things to limit thermal losses via the exhaust gas enthalpy flow and / or to minimize engine friction losses due to charge exchange.

[0358] Starting from this “normal state without EGR”, the inventive procedure proposes in particular to maximize the boost pressure, so that, for example, an increased boost pressure results, e.g. a boost pressure of 1.5-1.7 bar and a fresh air mass flow of, for example, 45 g / s and, due to the deactivated external EGR and the relatively small fuel mass, also an exhaust gas mass flow of about 45 g / s.

[0359] In conjunction with the installation or activation of a charge gas cooler bypass 31b, this results not only in a certain increase in fuel consumption but also in improved cabin heating.

[0360] The cabin heating effect is particularly effective when the injection timing is simultaneously adjusted to increase fuel consumption and further raise exhaust gas temperature and enthalpy. This, in turn, increases boost pressure and intake air temperature, etc., as described in DE 10 2009 042 745 A1. It is particularly important to note that the aforementioned 45 g / s fresh air mass flow at the specified operating point is only achievable for some engines in conjunction with these interactions to increase fuel consumption in line with heating performance.

[0361] In particular, even the increase in exhaust gas enthalpy through modified injection times and / or corresponding combustion control, aimed at increasing fuel consumption, provides a certain increase in boost pressure, even if the charging system does not have a device for varying the boost pressure. Therefore, the above-mentioned procedure can be advantageously used to improve heating performance, albeit with certain limitations. The fresh air mass flow without external EGR is then, particularly preferably, still around 30-35 g / s, despite the charge air cooler deactivation according to the invention.

[0362] In addition to or as an alternative to changing the injection times, it is proposed according to the invention, among other things, to increase fuel consumption by means of the second EGR throttle valve 31dk by increasing exhaust back pressure in the main exhaust stream.

[0363] With the EGR valve 14 closed and little / no valve overlap of the engine's charge exchange valves, the fresh air mass flow – starting from the above example of 45 g / s at maximum boost pressure and without throttling with valve 31dk – only drops by a few g / s, depending on the extent of the throttling, e.g. to 35-40 g / s.

[0364] If a relatively tight 31dk throttle valve is available, it can be particularly advantageous, depending on the cabin heating requirements, to implement a very strong throttle and set the fresh air mass flow to values ​​in the range of 20-35 g / s. A lower fresh air mass flow then also means a lower exhaust gas mass flow and lower exhaust gas losses compared to the above case with 45 g / s without throttle.

[0365] The optimal throttle setting depends on the engine and is determined, among other things, by the existing and / or adjustable valve overlap of the charge exchange valves, but also by the extent to which the throttle alone should / can induce the required increase in fuel consumption or whether additional fuel injection times, etc., to increase heating performance can be used.

[0366] In particular, an extremely strong reduction in the fresh air mass flow with deactivated external EGR is not easily possible, among other things because of potential fuel dilution and increased pollutant emissions.

[0367] Nevertheless, particularly in cases of low heating power deficit and for fuel economy, a method that achieves a very high internal EGR with moderate throttling via valve 31dk is also useful. This is accomplished by setting a corresponding valve overlap, or by using a valve overlap that is already present on the base engine, and by making no or only a minor adjustment to the injection timing. The fresh air mass flow is preferably set at no less than approximately 20-25 g / s.

[0368] Such or similar procedures with high internal EGR are particularly interesting when external EGR cannot be activated for extended periods of time in some engines or operating conditions, and especially when charge air cooler deactivation is not available at all.

[0369] With activated external EGR and high external EGR rates with corresponding turbocharger effect, the inventive method makes it particularly possible to reduce the fresh air mass flow and the exhaust gas mass flow to values ​​significantly below 20 g / s. Values ​​of 10-15 g / s are not only achievable here due to the synergies of the invention, but are particularly recommended for good cabin heating performance with low fuel consumption.

[0370] Once the engine is largely warmed up, fuel-optimized boost pressures and fuel-optimized external EGR rates with charge air cooler deactivation are ultimately the means of choice to correct minor cabin heating performance deficits.

[0371] These numerical examples for a 2-liter turbodiesel engine at 50 km / h are of course only to be considered exemplary and were taken in the exemplary configuration of Fig.1 with ia advantageous numerical values, in particular in a highly simplified manner, or explained, in order to finally outline the invention once again in broad terms.

Claims

[1] Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) with turbocharging (31tt / 31tv) and charge gas cooling with a charge gas cooler (31k), with a low-pressure exhaust gas recirculation with a first EGR control valve (14) and with a low-pressure EGR branch (11, 11lpegr), which temporarily mixes exhaust gas with the fresh air from a fresh air path (10f) in a main exhaust gas stream (10ft) via the low-pressure EGR branch (11, 11Ipegr) upstream of the charge gas cooler (31k) while partially closing a second EGR control valve (31dk), in particular an exhaust gas throttle valve (31dk), and with a coolant pump (7 and / or 2), which conveys the coolant of an engine cooling circuit to a cabin heater heat exchanger (4) and finally back to the internal combustion engine (1), characterized by, that the fuel consumption of the internal combustion engine (1) is temporarily artificially increased by an engine control unit (20) in the event of increased waste heat demand, in particular in the event of high cabin heating demand, by closing the first EGR control valve (14) and by throttling the main exhaust gas flow in the direction of the maximum permissible values ​​of the residual gas remaining in the combustion chamber and / or the exhaust back pressure by the second EGR control valve (31dk). [2] Method according to claim 1, characterized by , that the engine control (16) makes cabin heating-promoting settings with an artificial increase in fuel consumption relative to normal operation without additional cabin heating power requirement when the first EGR control valve (14) is closed, open or regulating, by • the effective boost pressure of the fresh air applied to the combustion chamber during charge exchange is adjusted towards the maximum possible value, in particular to a value that is at least 25% above the ambient pressure or the boost pressure during normal operation and that is preferably at least 1.5 bar when the vehicle is stationary and at least 1.9 bar when driving at constant speeds of 40 to 50 km / h, and / or • by shifting the fuel injection timing(s) such that the first injection(s) before TDC is / are advanced by at least 5° crank angle and / or the last injection(s) after TDC are retarded by at least 5° crank angle, and / or • that the effective fresh air mass flow m L,effthe combustion to reduce a cabin heating performance deficit at engine speeds below 1500 rpm during the warm-up phase, at least temporarily, especially after activation of the external EGR via the first EGR control valve (14), is less than 50% of a value corresponding to the displacement volume V H , the engine speed n and the ambient air density raw L,Umgebung according to the equation m L,ref = ((n / 2) / 60) * V h * raw L,Umgebung ) formed reference fresh air mass flow m L,ref . [3] Method according to one of claims 1-2, characterized by , that this results in the deactivation of the charge gas cooler. [4] Method according to any one of claims 1-3, characterized by , that after an initial phase with the first EGR control valve (14) closed, supplementary or alternative heating power increase measures are used during the warm-up phase, which do not induce any additional heating power-oriented fuel consumption, and • that a reduction of the coolant flow rate through the internal combustion engine (1) is carried out in the direction of the values ​​permissible for safe engine operation and / or particularly preferred for heating performance, • that a charge gas cooler deactivation takes place and • that during the warm-up phase the internal or external EGR is activated and the throttling is reduced by the second EGR control valve (31dk). [5] Method according to any one of claims 1-4, characterized by, that after an initial phase with the first EGR control valve (14) closed, supplementary or alternative heating performance enhancement measures are used during the warm-up phase, which induce an additional heating performance-oriented fuel consumption increase, whereby a division into separate combustion before and after top dead center results in an increase in the combustion chamber wall temperature and the compression temperature of the fuel gas at the start of combustion relative to the corresponding crankshaft position in normal operation without cabin heating performance-oriented fuel consumption increase. [6] Method according to any one of claims 1-4, characterized by, that after an initial phase with the first EGR control valve (14) closed, supplementary or alternative heating performance enhancement measures are used during the warm-up phase, which induce an additional heating performance-oriented increase in fuel consumption, whereby the fuel injection and / or ignition and / or the EGR rate is also adjusted by the engine control unit when EGR is activated, resulting in increased fuel consumption in favor of improved cabin heating effect. [7] Method according to any one of claims 1-6, characterized by, that multiple injections of fuel with first and second injections take place and thereby generate two separate combustions that are largely, in particular to more than 90%, complete in themselves, wherein the shift of the first injection(s) is such that the conversion of the fuel introduced for the first combustion is largely completed before the top dead center of the compression stroke and that the shift of the second injection(s) is such that the second combustion begins after the top dead center (TDC) of the compression stroke. [8] Method according to any one of claims 1-7, characterized by, that the fuel mass of the first combustion completed before top dead center (TDC) is 40-60% of the fuel mass of the combustion beginning after top dead center (TDC), and in particular that a first main injection takes place before top dead center (TDC) with attached pre-injection(s) and a second main injection takes place after top dead center (TDC) with attached pre-injection(s). [9] Method for increasing the coolant-side engine waste heat on demand for cabin heating purposes in a motor vehicle with a turbocharged internal combustion engine (1) which has a low-pressure exhaust gas recirculation with a charge gas cooler (31k) which cools the mixed gas compressed at a compressor (31tv) consisting of the combustion fresh air drawn in from the environment via a fresh air path (10f) and the exhaust gas recirculated on the low-pressure side in a low-pressure EGR branch (11Ipegr, 11), in particular a method according to one of claims 1-8, characterized by , that the engine control unit (20) exhibits a cabin heating power deficit after a cold start during a warm-up phase • below a warm-up criterion of the combustion engine (1) or the charge gas cooler (31k) and / or an EGR cooler (3) in the low-pressure EGR branch (11lpegr, 11) with an EGR control valve (14) keeps the low-pressure EGR branch (11lpegr, 11) closed and an exhaust gas throttle valve (31dk) in the main exhaust gas flow (10ft) downstream of the exhaust gas extraction point of the low-pressure exhaust gas recirculation is adjusted towards strong throttling, so that increased internal engine exhaust gas recirculation and / or increased fuel consumption due to increased charge exchange losses heats the coolant faster and • in particular that this is accompanied by a shift in injection times that increases fuel consumption, and • that if this warm-up criterion of the internal combustion engine (1) or the charge gas cooler (31k) and / or the EGR cooler (3) is exceeded, the EGR control valve (14) activates the low-pressure exhaust gas recirculation in the low-pressure EGR branch (11lpegr, 11) and, in conjunction with the exhaust gas throttle valve (31dk), sets a target value of the EGR rate, in particular a cabin heating performance-oriented EGR rate of more than 40%. [10] Method for increasing the coolant-side engine waste heat on demand for cabin heating purposes in a motor vehicle with a turbocharged internal combustion engine (1) which has a low-pressure exhaust gas recirculation with a charge gas cooler (31k) which cools the mixed gas compressed at the compressor (31tv) of a mixed gas branch (10ab) consisting of the combustion fresh air drawn in from the environment via a fresh air path (10f) and the exhaust gas recirculated on the low-pressure side via a low-pressure EGR branch (11lpegr, 11), in particular a method according to one of claims 1-9, characterized by , that the engine control (20) • below a first warm-up criterion of the internal combustion engine (1) or the charge gas cooler (31k) and / or an EGR cooler (3) in the low-pressure EGR branch (11lpegr, 11) with a first EGR control valve (14) closes the low-pressure EGR branch (11lpegr, 11) and keeps an exhaust gas throttle valve (31dk) open in the main exhaust gas stream (10ft) downstream of the exhaust gas extraction point of the low-pressure exhaust gas recirculation and in particular adjusts the boost pressure and the combustion fresh air mass flow (10f) towards the maximum values ​​and • that if this first warm-up criterion is exceeded, the exhaust gas throttle valve (31dk) is adjusted towards throttling and the EGR valve (14) remains closed, so that a high internal exhaust gas recirculation and / or increased fuel consumption due to increased charge exchange losses heats the coolant more quickly, which is particularly accompanied by a shift in injection times that increases fuel consumption, and • that if a second warm-up criterion of the internal combustion engine (1) or the charge gas cooler (31k) and / or the EGR cooler (3) is exceeded, the EGR control valve (14) activates the low-pressure exhaust gas recirculation in the low-pressure EGR branch (11lpegr, 11) and, in conjunction with the exhaust gas throttle valve (31dk), sets a target value of the EGR rate, in particular a cabin heating performance-oriented EGR rate of more than 40%. [11] Method according to any one of claims 1-10, characterized by, that the activation of the low-pressure exhaust gas recirculation in the low-pressure EGR branch (11lpegr, 11) is based on a warm-up criterion which ensures minimum temperatures of the surfaces of the components in contact with the exhaust gas in the low-pressure EGR branch (11lpegr, 11) and / or in the mixed gas branch (10ab), in particular minimum surface temperatures of more than 25°C and / or above the dew point of the locally applied gas mixture, based on the previous engine operation without low-pressure exhaust gas recirculation. [12] Method according to any one of claims 1-11, characterized by , that the activation of the low-pressure exhaust gas recirculation in the low-pressure EGR branch (11Ipegr, 11) only occurs when a minimum coolant temperature is exceeded, in particular when a minimum coolant temperature of +25°C is exceeded. [13] Method according to any one of claims 1-12, characterized by , that the charge gas cooler (31k) is deactivated by a coolant-side shut-off device (31sv). [14] Method according to any one of claims 1-12, characterized by , that the charge air cooler (31k) is deactivated by a cooling air-side shutdown device (31b). [15] Method according to any one of claims 1-14, characterized by , that an internal combustion engine (1) with variable timing of the intake and / or exhaust valves is used and a phase with closed EGR control valve (14) is set by a heat output-oriented change of the valve timing by means of the engine control (20), wherein the engine-internal exhaust gas recirculation is set towards the maximum possible values ​​and wherein at least temporarily in favor of a reduced fuel consumption the heat output-oriented maximization of the exhaust gas throttling and the charge exchange losses is dispensed with. [16] Method according to claim 15, characterized by, that high internal engine EGR rates are set at two different heating-power-oriented positions of the engine-side charge exchange valves depending on the extent of the heating power deficit, so that in the case of a very high heating power deficit, the exhaust gas throttle valve (31dk) is throttled as much as possible with a comparatively high increase in fuel consumption, and in the case of a moderate heating power deficit, the exhaust gas throttle valve (31dk) is throttled as little as possible with a comparatively low increase in fuel consumption. [17] Method according to any one of claims 1-16, characterized by , that in comparison to normal engine operation, the relevant / only cabin heating performance-oriented engine control measures are a permanent closing of the EGR control valve (14) as well as a maximization of the engine's internal EGR rate by throttling the exhaust gas throttle valve (31dk) and, in particular, an additional adjustment of the timing of the engine intake and / or engine exhaust valves. [18] Method according to any one of claims 1-17, characterized by that it is used exclusively when the engine is idling with the vehicle stationary and / or during overrun and / or when driving downhill with engine loads close to / less than zero. [19] Device for increasing the coolant-side engine waste heat for cabin heating purposes in a motor vehicle with a turbocharged internal combustion engine (1) which has a low-pressure exhaust gas recirculation with a charge gas cooler (31k) which cools the mixed gas compressed at a compressor (31tv) of a mixed gas branch (10ab) consisting of the combustion fresh air drawn in from the environment via a fresh air branch (10f) and the exhaust gas recirculated on the low-pressure side via a low-pressure EGR branch (11, 11Ipr), in particular a device for carrying out one of the methods according to one of claims 1-18, characterized by, that it is stored in the engine control unit (20) that after a cold start during a warm-up phase with a cabin heating power deficit • below a warm-up criterion of the internal combustion engine (1) and / or the charge gas cooler (31k) and / or an EGR cooler (3) in the low-pressure EGR branch (11Ipegr, 11) with a first EGR valve (14) the low-pressure EGR branch (11lpegr, 11) is closed and an exhaust gas throttle valve (31dk) in a main exhaust gas stream (10ft) downstream of the exhaust gas extraction point of the low-pressure exhaust gas recirculation is adjusted towards strong throttling, so that a high in-engine exhaust gas recirculation and / or increased fuel consumption due to increased charge exchange losses heats up the coolant faster, and • that if this warm-up criterion of the internal combustion engine (1) or the charge gas cooler (31k) and / or the EGR cooler (3) is exceeded, the EGR control valve (14) activates the low-pressure exhaust gas recirculation in the low-pressure EGR branch (11lpegr, 11) and, in conjunction with the exhaust gas throttle valve (31dk), a target value of the EGR rate, in particular a cabin heating performance-oriented EGR rate of more than 40%, is set. [20] Device according to claim 19, characterized by , that in this operating mode the engine control (20) increases the engine idle speed when the vehicle is stationary by at least 30%, in particular to 1200-1500 rpm, in order to temporarily increase cabin heating performance. [21] Method according to any one of claims 1-18, characterized bythat this is assigned to a vehicle with an internal combustion engine (1) and a low-pressure EGR system, which does not have an external auxiliary heater for cabin heating purposes, in particular no electric PTC auxiliary heater for heating the cabin air, and in particular that cooling circuit and / or heating circuit-side heating performance enhancement measures are used which are based on a temporary reduction of the total coolant flow rate through the internal combustion engine (1). [22] Method for operating a motor vehicle with an internal combustion engine (1) with low-pressure exhaust gas recirculation, characterized by , that an engine control unit (20) deactivates the external exhaust gas recirculation via a low-pressure EGR branch (11, 11Ipegr) in contrast to normal operation without a heating power deficit, whereby an EGR control valve (14) closes, and • in a first operating mode deviating from normal operation, with settings for regenerating a diesel particulate filter (31dpf) or another exhaust aftertreatment component, a throttling of the combustion fresh air mass flow is carried out with an intake-side or charge-gas-side throttle valve (31sdk), so that the charge density in the combustion chamber and in the exhaust stream is reduced and • that the engine control (20) in a second operating mode deviating from normal operation, with a setting for temporary cabin heating power increase, opens the intake-side or charge gas-side throttle valve (31sdk) and performs an exhaust-side throttling of the combustion fresh air mass flow with an exhaust-side throttle valve (31dk), through which in particular the entire main exhaust flow (10ft) leaving the exhaust system towards the environment flows, so that the charge density in the combustion chamber and in the exhaust system increases and in particular that the cabin heating effect is thereby improved in the event of a heating power deficit by means of the engine control (20). [23] Method for operating a motor vehicle with an internal combustion engine (1) with low-pressure exhaust gas recirculation, characterized by, that an engine control unit (20) deactivates the external exhaust gas recirculation via a low-pressure EGR branch (11, 11Ipegr) in contrast to normal operation without a heating power deficit, whereby an EGR control valve (14) closes, and • In a first operating mode deviating from normal operation, with a setting for preheating the exhaust system before initiating an additional fuel injection for regenerating a diesel particulate filter (31dpf) or other exhaust aftertreatment component, an exhaust-side throttling of the combustion fresh air mass flow is performed with an exhaust-side throttle valve (31dk), through which the entire main exhaust flow (10ft) leaving the exhaust system towards the environment flows, so that the charge density in the combustion chamber and in the exhaust stream is increased and the preheating of the exhaust system before initiating the additional fuel injection is improved and • in a second operating mode that deviates from normal operation, with a setting with additional fuel injection for regenerating a diesel particulate filter (31 dpf) or another exhaust aftertreatment component, a throttling of the combustion fresh air mass flow with an intake-side or charge-gas-side throttle valve (31sdk) is carried out, so that the charge density in the combustion chamber and in the exhaust stream is reduced. [24] Method according to claim 23, characterized by , that the engine control (20) in a third operating mode deviating from normal operation with a setting for temporary cabin heating power increase performs an exhaust-side throttling of the combustion fresh air mass flow with the exhaust throttle valve (31dk), so that the charge density in the combustion chamber and in the exhaust system is increased and the cabin heating effect is improved. [25] Method for operating a motor vehicle with an internal combustion engine (1) with low-pressure exhaust gas recirculation and a throttle device (31dk) in the main exhaust gas mass flow (10ft), characterized by , that an engine control unit (20) • upon occurrence of a first switching criterion, which indicates a driving situation with a stationary / braked vehicle and cabin heating requirement and • when a second switching criterion occurs simultaneously, which characterizes a minimum available time interval for restarting / accelerating and is characterized in particular by a corresponding position of the brake pedal and / or the handbrake and / or the clutch, • performs an exhaust-side throttling of the combustion fresh air mass flow with an exhaust-side throttle valve (31dk) through which the entire main exhaust flow (10ft) leaving the exhaust system towards the environment flows. [26] Method according to claim 25, characterized by, that the engine control unit (20) deactivates the external exhaust gas recirculation by closing an EGR control valve (14). [27] Method according to one of claims 25-26, characterized by , that additionally, an adjustment of the injection times to support cabin heating performance is carried out, resulting in increased fuel consumption. [28] Method according to one of claims 1-18 or 21-27, characterized by , that the turbine (31tt) of a turbocharger (31tt / 31tv) has a guide vane adjustment or the turbocharger (31tt / 31tv) is multi-stage, and that the charging is adjusted simultaneously with the throttling of the exhaust mass flow by means of an exhaust throttle valve (31dk) which is located in the main exhaust stream (10ft) downstream of the turbine (31tt) in the direction of maximum boost pressure. [29] Method according to one of claims 1-18 or 21-28, characterized by, that the internal combustion engine (1) is associated with a low-pressure exhaust gas recirculation system with a low-pressure EGR branch (11, 11lpegr), a charge gas cooler (31k) and a charge gas cooler deactivation device (31b, 31sv) controlled by the engine control unit (20), which are activated at at least one operating point with comparable engine load on the part of the vehicle drive • is deactivated in an initial emission-optimized setting with exhaust gas recirculation, so that the mixture of fresh air and recirculated exhaust gas is optimally cooled and • is activated in a second cabin heating performance-optimized setting with exhaust gas recirculation, so that the charge gas cooler (31k) is ineffective and the mixture of fresh air and recirculated exhaust gas is not cooled. [30] Method according to claim 29, characterized by, that the charge gas cooler (31k) is temporarily deactivated by means of a charge gas-side device (31b) or a coolant-side device (31sv), wherein the intake system of the internal combustion engine (1) and the internal combustion engine (1) itself are preheated, at least in very cold environments, by operation without low-pressure exhaust gas recirculation before the engine control activates the low-pressure exhaust gas recirculation. [31] Method for operating a motor vehicle with an internal combustion engine (1) with a low-pressure exhaust gas recirculation system comprising a low-pressure EGR branch (11, 11lpegr), an EGR control valve (14) and an exhaust gas throttle valve (31dk) in a main exhaust gas mass flow (10ft), characterized by , that the low-pressure exhaust gas recirculation has a charge gas cooler (31k) and a charge gas cooler deactivation device (31b, 31sv) controlled by an engine control unit (20), which is activated at at least one operating point with comparable engine load on the part of the vehicle drive • is deactivated in an initial emission-optimized setting with exhaust gas recirculation, so that the mixture of fresh air and recirculated exhaust gas is cooled at the charge gas cooler (31k) and • is activated in a second cabin heating performance-optimized setting with exhaust gas recirculation, so that the charge gas cooler (31k) is ineffective and the mixture of fresh air and recirculated exhaust gas is not cooled, and • that the charge gas cooler (31k) is deactivated by means of the charge gas-side charge gas cooler deactivation device (31b) or the coolant-side charge gas cooler deactivation device (31sv) in a temporary setting without exhaust gas recirculation in the low-pressure EGR branch (11, 11lpegr), in which the intake system of the internal combustion engine (1) and the internal combustion engine (1) itself are preheated, at least in very cold environments, by operation without exhaust gas recirculation in the low-pressure EGR branch (11, 11lpegr) before the engine control (20) activates the exhaust gas recirculation in the low-pressure EGR branch (11, 11lpegr). [32] Low-pressure EGR device for a turbocharged internal combustion engine (1) in a motor vehicle, in particular a low-pressure EGR device for carrying out the method according to one of claims 1-18 or 21-31, characterized by, that the engine control (20) is designed so that, with external exhaust gas recirculation activated, the recirculated exhaust gas is mixed with a combustion fresh air mass flow from a fresh air branch (10f) before compression at a compressor (31tv) and additionally heated by compression at this compressor (31tv), and that the thus heated charge gas, consisting of combustion fresh air and recirculated exhaust gas, is kept at a higher level compared to normal operation with an activated or flow-through charge gas cooler (31k) by deactivating or bypassing a charge gas cooler (31k) during engine warm-up and / or operation with a cabin heating power deficit. [33] Device according to claim 32, characterized by, that the engine control (20) is designed to temporarily improve the cabin heating potential by inducing increased fuel consumption with increased exhaust gas temperature in a situation with high cabin heating demand, especially until a minimum coolant temperature is reached, which, with the charge gas cooler (31k) deactivated or bypassed, benefits the cabin heating performance to an increased degree. [34] Device according to claim 33, characterized by , that the engine control unit (20) is designed to ensure that, in conjunction with the deactivation or bypassing of the charge air cooler (31k) • utilization of the exhaust gas enthalpy in the form of the recirculated exhaust gas including its compression and the resulting heating at the compressor (31tv) and / or • the exhaust gas enthalpy is used in the form of increasing the charge air side compression pressure and charge air side compression temperature in interaction with a turbo compressor (31tv) driven by the exhaust gas turbine (31tt). [35] Device according to one of claims 32-34, characterized by , that the engine control (20) is designed to allow temporary use of the increase in charge air-side compression pressure and charge air-side compression temperature by means of charge air cooler deactivation without activation of external exhaust gas recirculation. [36] Device according to one of claims 32-35, characterized by , that the engine control (20) is designed to deactivate the external exhaust gas recirculation to simplify the application and / or to avoid risks to the turbo compressor (31tv) during early warm-up, especially the first 3-5 minutes. [37] Device according to one of claims 32-35, characterized by , that the engine control (20) is designed to deactivate the external exhaust gas recirculation to simplify the application and / or to avoid risks to the turbo compressor (31tv) until a coolant temperature and / or cabin heating potential no longer requires the engine to be adjusted towards higher fuel consumption. [38] Device for carrying out the method according to one of claims 1-18 or 21-31, characterized by, that the engine control unit (20) is configured to employ a charge gas cooler deactivation device (31b) which consists of a charge gas-side charge gas cooler bypass branch (10b) switchable by the engine control unit (20) and in particular that this charge gas cooler bypass branch (10b) has a mean flow cross-section which is less than 50% of the mean flow cross-section of the charge gas lines (10a, 10ab, 12) connected to the charge gas cooler (31k) and / or has a mean inner diameter of less than 25 mm. [39] Device according to claim 32, characterized by , that the internal combustion engine (1) has a charge gas cooler (31k) for cooling the mixed gas of combustion fresh air and recirculated exhaust gas and additionally a cool water-cooled EGR cooler (3) in a low-pressure EGR branch (11, 11Ipegr) which only cools the recirculated exhaust gas in a first cooling stage.

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