DE102020211598A1 - Hybrid motor vehicle and operating method for operating a hybrid vehicle - Google Patents

Abstract

The invention relates to hybrid motor vehicles with a drive system (1) having an internal combustion engine (2) and an electric motor (3), comprising an exhaust gas cleaning system (10) connected to the internal combustion engine (2) of the vehicle with an electrical heating element (22) and several exhaust gas cleaning systems serving, in particular with regard to a NOx reduction catalytically effective exhaust gas cleaning components and a control device for controlling an operation of the drive system (1) and exhaust gas cleaning system (10), the control device being designed to control the operation of the drive system (1) so that a The exhaust gas mass flow emitted by the internal combustion engine (2) does not exceed a specifiable upper exhaust gas mass flow limit and / or does not fall below a specifiable lower exhaust gas mass flow limit, at least during a heating operation with energization of the heating element (22) for heating the exhaust gas, the upper exhaust gas mass flow limit and the lower exhaust gas mass flow limit in A. The invention also relates to an operating method for operating a hybrid vehicle with an internal combustion engine (2) and an electric motor (3).

Description

The invention relates to a hybrid vehicle with a drive system having an internal combustion engine and an electric motor according to the preamble of claim 1 and an operating method for operating such a hybrid vehicle according to the preamble of claim 10.

Hybrid vehicles with a drive system having an internal combustion engine and an electric motor are generally characterized by a comparatively low fuel consumption. Nevertheless, exhaust gas aftertreatment is essential for low emissions of pollutants, in particular nitrogen oxides (NOx). However, when operating the hybrid vehicle, the problem of temperature control of the exhaust gas aftertreatment components to be provided for this arises to a particular degree, since less exhaust gas is made available due to the internal combustion engine being switched off at times compared to vehicles with a purely internal combustion engine drive, which could be used for temperature control of the exhaust gas aftertreatment system. In addition, a purely electric motor drive cools down the exhaust gas cleaning components, which must therefore be brought back to operating temperature as quickly as possible when the internal combustion engine is restarted in order to keep pollutant emissions low. To solve these problems, various proposals have been made to integrate an electrical heating element into the exhaust gas cleaning system, which is energized as required and thus at least supports the heating of the exhaust gas aftertreatment components to operating temperature. So reveals the DE 10 2014 223 490 A1 for a vehicle with a diesel engine, possibly designed as a hybrid vehicle, an exhaust gas aftertreatment device which has an SCR catalytic converter and an NOx storage catalytic converter that can be heated via an electrical heating device to reduce NOx. A control unit can control the heating device in such a way that the NOx storage catalytic converter can be heated independently of an exhaust gas temperature specified by the diesel engine.

However, this measure is often not sufficient to operate a hybrid vehicle with the lowest possible emission of pollutants, in particular NOx, and with the lowest possible fuel consumption. In particular, an interaction of the heating effects of exhaust gas and electrical heating device can be advantageous.

The object of the invention is therefore to specify a hybrid vehicle and an operating method for operating a hybrid vehicle which enable a further improvement in terms of pollutant emissions and fuel consumption.

This object is achieved by a hybrid motor vehicle with the features of claim 1 and by a method with the features of claim 10. Advantageous refinements and developments of the invention are the subject matter of the respective subclaims.

The hybrid vehicle according to the invention has a drive system with an internal combustion engine and an electric motor. Furthermore, it comprises an exhaust gas purification system connected to the internal combustion engine of the vehicle with an electrical heating element and several exhaust gas purification components which are used for exhaust gas purification, in particular with regard to NOx reduction, catalytically effective exhaust gas purification components and a control unit for controlling the operation of the drive system and exhaust gas purification system. According to the invention, the control device is designed to control the operation of the drive system in such a way that an exhaust gas mass flow rate emitted by the internal combustion engine does not exceed a specifiable upper exhaust gas mass flow limit and / or does not fall below a specifiable lower exhaust gas mass flow limit, at least in a heating mode with energization of the heating element for heating the exhaust gas The upper exhaust gas mass flow limit and the lower exhaust gas mass flow limit can be specified as a function of a temperature and / or a performance of at least one of the exhaust gas cleaning components.

By limiting or restricting the exhaust gas mass flow, raw emissions and fuel consumption can be kept low on the one hand. On the other hand, by limiting or restricting the exhaust gas mass flow according to the invention as a function of a temperature and / or a performance of at least one of the exhaust gas cleaning components, the total amount of pollutants emitted into the environment can be kept low. The performance of a particularly catalytically active exhaust gas cleaning component is to be understood as its ability to catalytically convert a respective pollutant, in particular NOx, or its ability to remove the pollutant from the exhaust gas. This ability is strongly dependent on temperature and throughput, especially at low temperatures. The invention therefore makes it possible in operating areas that are critical to exhaust gas purification, in which additional heating takes place by energizing the heating element for heating or to maintain an operating temperature, to utilize a catalytic exhaust gas purification effect of the exhaust gas purification components as much as possible. The measure according to the invention is therefore preferably taken in connection with a cold start or a restart of the internal combustion engine. However, it can also be taken in operating areas with a temperature recognized as being critically low for one or more of the exhaust gas cleaning components.

The internal combustion engine of the drive system is preferably made from a diesel engine. However, it can also be designed as a gasoline engine. The electric motor can be designed, for example, as a direct current motor or as a synchronous or asynchronous three-phase motor. To deliver a drive power, it is supplied by a rechargeable store for electrical energy, generally referred to as a battery or traction battery. The electric motor can preferably also be operated as a generator and convert mechanical power taken up by the drive wheels or the internal combustion engine to charge the battery.

As a hybrid vehicle, a design as a so-called serial or parallel or also power-split hybrid comes into consideration. The drive system is preferably designed in such a way that a drive torque can be applied to driven wheels of the vehicle both by the internal combustion engine alone and by the electric motor alone and also by both at the same time. In order to limit or limit the exhaust gas mass flow, the internal combustion engine and the electric motor may be operated in conjunction with one another. In order to avoid exceeding the upper exhaust gas mass flow limit when there is a corresponding power requirement, it is provided that the electric motor is additionally used to deliver drive power. Conversely, if necessary, to avoid falling below the lower exhaust gas mass flow limit, the drive power of the electric motor can be reduced accordingly and that of the internal combustion engine can be increased. The control for this is taken over by the control unit. The exhaust gas mass flow limits are preferably taken from stored characteristic curves or characteristic fields for the at least one exhaust gas cleaning component.

In addition to the design of the control device for controlling the drive system, the control device can also control the operation of the exhaust gas cleaning system and in particular the heating element. To carry out the control functions, a connection of the control device with corresponding sensors for recording operating states or operating parameters, such as sensors for recording exhaust gas or operating medium temperatures, pollutant concentrations or operating medium throughputs, is provided. The control device is also connected to actuators for influencing the operating states or the operating parameters in order to control them as intended. Actuators can be, for example, a fuel injection system of the internal combustion engine, flaps, valves or pumps for setting operating medium throughputs. The sensor signals received by the control device are converted into control signals for the actuators by hardware and / or software implemented in the control device and output to the actuators. For this purpose, the control device can comprise several control modules which are integrated into a single device or are designed as separate modules.

In an embodiment of the invention, the exhaust gas purification system has the electrical heating element, a first oxidation-catalytically active exhaust gas purification component, in particular designed as a NOx storage catalyst, a first SCR-catalytically active exhaust gas purification component, a second SCR-catalytically active exhaust gas purification component and arranged one behind the other as seen in the flow direction of the exhaust gas emitted by the internal combustion engine a second oxidation-catalytically active exhaust gas cleaning component, with a metering device for introducing an ammonia-containing reducing agent into the exhaust gas being provided on the input side of the first and the second SCR-catalytically active exhaust gas cleaning component.

In principle, the elements in the exhaust gas cleaning system can also be arranged in a different order. For example, several heating elements, which are designed in particular as heating disks, can be provided. In addition, an SCR-catalytically effective exhaust gas cleaning component can also be combined with a diesel particulate filter and / or an SCR-catalytically effective exhaust gas cleaning component can be arranged upstream of an SDPF.

The heating element, first oxidation-catalytic exhaust gas cleaning component, first SCR-catalytic exhaust-gas cleaning component, second SCR-catalytic exhaust-gas cleaning component and second oxidation-catalytically effective exhaust-gas cleaning component are thus traversed in this order by exhaust gas emitted by the internal combustion engine.

The electrical heating element is preferably designed as a resistance heater and can be supplied with power from the vehicle battery. Preference is given to a design as a film body with a wound or folded metal film structure which can be heated by energization and through which exhaust gas can flow. A nominal power consumption of several kW, for example approximately 4 kW, can be provided. Although a coating-free design is preferred, a catalytic coating, in particular a oxidation-catalytically effective coating may be provided.

The first exhaust gas cleaning component which is effective in terms of oxidation catalysis can be designed, for example, as a classic diesel oxidation catalyst. However, a design as a NOx storage catalytic converter is preferred. For this purpose, channels of a ceramic honeycomb body are provided with a coating which, on the one hand, has an oxidation-catalytic effect in relation to an oxidation of, in particular, hydrocarbons (HC) and carbon monoxide (CO), and, on the other hand, can store NOx specifically under oxidizing conditions. In a regeneration process, these can be released again, especially under reducing conditions, and at least partially converted into harmless nitrogen with catalytic support. Storage of NOx can also take place at comparatively low temperatures of around 150 ° C or less. This enables NOx to be removed from the exhaust gas even when the exhaust gas cleaning system is comparatively slightly heated.

The SCR-catalytically active exhaust gas cleaning components are preferably also ceramic honeycomb bodies through which exhaust gas can flow, but which are provided here with a coating that can _{catalyze a selective reduction of NOx by means of a reducing agent, in particular ammonia (NH 3} ). It can also be designed as a so-called full catalytic converter. These exhaust gas cleaning components preferably also have a certain NH3 storage capacity. The SCR-catalytically active exhaust gas cleaning components typically enable NOx to be removed from the exhaust gas from around 150 ° C.

The second exhaust gas purification component, which is effective as an oxidation catalytic converter, is preferably an oxidation catalytic converter, also referred to as a blocking catalytic converter, which can in particular catalyze an oxidation of ammonia. As a result, an undesirable slip of odorous and harmful ammonia can be avoided.

The metering devices are preferably designed as metering valves with which NH ₃ or a _{reducing agent containing NH 3} in free or bound form, in particular an aqueous urea solution, can be added to the exhaust gas in a metered manner. The fact that two SCR-catalytic exhaust gas cleaning components are provided, each with upstream and optionally actuatable metering devices, enables further improved NOx removal. For example, in the case of a temperature gradient occurring along the exhaust gas cleaning system, NOx removal can already take place when the first component but not the second has reached its operating temperature.

In a further embodiment of the invention, the control unit is designed to control the operation of the drive system in such a way that an exhaust gas mass flow output by the internal combustion engine does not exceed a specifiable upper exhaust gas mass flow limit during normal operation without energizing the heating element and / or does not fall below a specifiable lower exhaust gas mass flow limit when the temperature and / or the performance of one or more of the exhaust gas purification components that are effective with regard to NOx reduction fall below a respectively predeterminable value. This can be the NOx storage catalytic converter and / or the first SCR-catalytically active exhaust gas cleaning component and / or the second SCR-catalytically active exhaust gas cleaning component. By limiting the exhaust gas mass flow to an upper limit value, it can be avoided in particular at comparatively low temperatures that the NOx storage catalytic converter or one of the SCR-catalytically active exhaust gas cleaning components lose their cleaning effect in an undesirable manner as a result of an excessively high exhaust gas mass flow. This extends an effective NOx reduction to comparatively low temperatures, at which the full cleaning effect of the corresponding catalytic converters is not yet achieved. On the other hand, further cooling is prevented if a lower exhaust gas mass flow limit is not undershot.

Similarly, a further embodiment of the invention provides that the control unit is designed to control the operation of the drive system in such a way that an exhaust gas mass flow emitted by the internal combustion engine does not exceed a specifiable upper exhaust gas mass flow limit in normal operation without current being supplied to the heating element when the temperature of the NOx Storage catalytic converter and / or the first SCR-catalytically active exhaust gas cleaning component and / or the second SCR-catalytically active exhaust gas cleaning component exceed a respective predeterminable value. In this way, thermal overloading of one of the exhaust gas cleaning components can be avoided.

The exhaust gas mass flow is limited or restricted, as described above, preferably by an interaction between the internal combustion engine and the electric motor controlled by the control device.

In a further embodiment of the invention, the electrical heating element, the NOx storage catalytic converter and the first SCR catalytically active Exhaust gas cleaning component is arranged in an engine compartment for the internal combustion engine, in particular close to the internal combustion engine, and the second SCR-catalytic exhaust gas cleaning component and the second exhaust gas cleaning component with an oxidation-catalytic effect are arranged remote from the internal combustion engine, in particular in an underbody area of the hybrid motor vehicle. As the NOx storage catalytic converter and the first SCR-catalytically active exhaust gas cleaning component are arranged close to the combustion engine, they can be warmed up particularly quickly by hot engine exhaust gas. An arrangement is particularly preferred in which the NOx storage catalytic converter is arranged directly behind the heating element and together with it in a common housing. The housing is preferably connected directly to the outlet of an exhaust gas turbocharger turbine.

In a further embodiment of the invention, the first SCR-catalytically active exhaust gas cleaning component is designed as a particle filter with an SCR-catalytically active coating. In this way, a filter function and a NOx removal function are combined in a space-saving manner. The particle filter is preferably designed as a so-called wall-flow filter with channels that are alternately closed on the inlet and outlet.

In a further embodiment of the invention, the first SCR-catalytically active exhaust gas cleaning component can also have a particle filter with an SCR-catalytically active coating and an additional SCR catalytic converter, these two components being arranged directly one behind the other in a common housing. In this case, the particle filter can be arranged directly in front of or also directly behind the SCR catalytic converter, as seen in the direction of the exhaust gas flow. It can also be provided that the SCR catalytic converter is arranged in front of the particle filter.

In a further embodiment of the invention, a first coolant circuit for temperature control of the internal combustion engine and a separate second coolant circuit for temperature control of the electric motor are provided, a first electric coolant pump being provided for the first coolant circuit and a second electric coolant pump being provided for the second coolant circuit, the first coolant pump being provided are connected to a first voltage supply and the second coolant pump to a second voltage supply and the first voltage supply provides a higher electrical voltage compared to the second voltage supply. This enables targeted temperature control of both the internal combustion engine and the electric motor in an energy-saving manner. The first coolant pump is preferably more powerful and designed for greater throughputs than the second coolant pump. The voltages of the power supplies can be 48 V and 12 V, for example. The first voltage supply is preferably implemented by the traction battery. It can also be provided that the second coolant pump is more powerful or equally powerful than the first coolant pump.

In a further refinement of the invention, the control device is designed to operate the first and / or the second coolant pump in a power-reduced operation with a speed that can be set lower than in normal operation. Operation at reduced speeds and thus with reduced power consumption is preferably carried out when, for example, it is determined on the basis of the power output by the internal combustion engine or the electric motor that a full coolant throughput is not absolutely necessary. This can be done in particular by a model-based determination of the required heat dissipation or cooling capacity. If the first or the second coolant pump is then operated at reduced speeds, a further reduction in consumption is achieved overall.

The method according to the invention is characterized by a heating operation for heating the exhaust gas cleaning system to operating temperature, the heating operation comprising a first and a subsequent second heating phase. In the first heating phase, when the internal combustion engine is not fired, the electric heating element is energized in such a way that a temperature of an exhaust gas purification component arranged downstream of the heating element in the exhaust gas purification system reaches or exceeds a predeterminable temperature limit. In the second heating phase with fired operation of the internal combustion engine, the electrical heating element continues to be energized and an early and / or a late fuel post-injection is provided for the internal combustion engine. Furthermore, in the second heating phase, the operation of the drive system is controlled in such a way that an exhaust gas mass flow rate emitted by the internal combustion engine does not exceed a specifiable upper exhaust gas mass flow limit and / or does not fall below a specifiable lower exhaust gas mass flow limit. Furthermore, according to the invention, normal operation is provided with exhaust gas cleaning components heated at least approximately to operating temperature, in which the internal combustion engine is operated in a first operating mode with minimized raw NOx emissions or in a second operating mode with minimized specific fuel consumption. The maximum efficiency of the exhaust gas aftertreatment is preferably always maintained, preferably always a minimum possible To be able to guarantee the overall level of emissions that is emitted to the environment.

Because the electrical heating element is energized in the first heating phase, the exhaust gas purification system and in particular an exhaust gas purification component arranged close behind the heating element, such as a NOx storage catalytic converter, can be preheated before the internal combustion engine is started. This can be done both when the vehicle is stationary and when it is moving. If the internal combustion engine is started and thus changes from unfired to fired operation, at least partial cleaning of the exhaust gas emitted is made possible as soon as exhaust gas begins to be emitted by the internal combustion engine.

In order to heat up the exhaust gas purification system further, in the second heating phase following the first heating phase, the heating element can be operated with a lower heating output than the nominal output. The heating output is preferably reduced as a function of a temperature for an exhaust gas cleaning component arranged close behind the heating element, such as, for example, a NOx storage catalytic converter or also the first or second SCR. This temperature can be determined metrologically using a sensor or a computer model.

With regard to the fuel post-injections, provision is preferably made for an early, co-burning post-injection of fuel to be carried out into at least one combustion chamber of the internal combustion engine. As a result, comparatively hot exhaust gas is emitted and the exhaust gas cleaning system continues to heat up quickly. The late fuel injection is then switched on, preferably also controlled by a temperature in the exhaust gas cleaning system. This is preferably designed as a non-burning post-injection, with which the exhaust gas is enriched with unburned fuel components. The unburned fuel constituents are at least partially oxidized with the release of heat in an oxidation-catalytically active exhaust gas cleaning component, which is already at least approximately heated to operating temperature at this point in time, for example in a NOx storage catalytic converter arranged behind the heating element. In this way, the exhaust gas cleaning system is further heated up quickly. With regard to the limitation or restriction of the exhaust gas mass flow carried out in the second heating phase, reference is made to the relationships already described above.

If the exhaust gas cleaning components are heated to at least approximately the operating temperature as a result of the heating operation, the heating measures, i.e. the energization of the heating element, and the early and late fuel post-injection are ended. Optionally, in particular as a function of the raw NOx emissions emitted into the environment, the internal combustion engine is then operated either in an operating mode with minimized NOx emissions or in an operating mode with minimized fuel consumption. In particular, the maximum efficiency of the exhaust gas aftertreatment is always maintained in order to always be able to guarantee a minimum possible overall emission level that is emitted to the environment.

In an embodiment of the operating method according to the invention, in an exhaust gas purification system which, viewed in the direction of flow of the exhaust gas emitted by the internal combustion engine, has the electrical heating element arranged one behind the other, a first exhaust gas purification component that is effective as an oxidation catalytic converter, in particular designed as a NOx storage catalytic converter, and at least one SCR-catalytically effective exhaust gas purification component, the power supply to Heating of the heating element set at least in the second heating phase as a function of a temperature and a NOx loading of the NOx storage catalytic converter. The NOx storage catalytic converter is preferably arranged directly behind the heating element placed close to the combustion engine.

Because both its temperature and its loading with stored NOx are taken into account when the NOx storage catalytic converter is heated, it can be achieved, on the one hand, that the NOx storage catalytic converter is further heated if necessary. On the other hand, with a high NOx load, reduced heating by the heating element can prevent stored NOx from being thermally desorbed and released into the environment when the SCR-catalytically active exhaust gas cleaning element is not yet ready for operation.

In a further embodiment of the method, the NOx storage catalytic converter is regenerated during the second heating phase. For this purpose, the internal combustion engine is operated at least temporarily with a rich fuel-air ratio and the operation of the drive system is controlled with the help of the electric motor so that an exhaust gas mass flow rate emitted by the internal combustion engine lies between a specifiable upper and a specifiable lower exhaust gas mass flow limit.

During the regeneration of the NOx storage catalytic converter, stored NOx is released and at the same time reduced to harmless nitrogen. A preferably comparatively short enrichment of the fuel-air ratio (λ) to a value of λ <1.0 carried out for this purpose causes the NOx storage catalytic converter and downstream exhaust gas cleaning components to heat up further. In addition, the NOx storage catalytic converter is returned to a state with a high NOx absorption capacity. Since regeneration of the NOx storage catalytic converter always consumes energy, it is particularly efficient to carry out this in the second heating phase when the heating element is already energized. The limitation of the exhaust gas mass flow ensures an optimal regeneration process.

In a further embodiment of the method, immediately after the internal combustion engine has been switched off, the heating element is heated in such a way that the NOx storage catalytic converter is raised to a temperature at which stored nitrogen oxides are at least partially thermally desorbed. The thermal desorption of previously stored NOx restores the NOx storage capacity, or at least improves it. The NOx storage catalytic converter is also regenerated in this way. When the internal combustion engine is restarted, it is therefore able to remove NOx from the exhaust gas. It is advantageous if a so-called low-temperature storage catalytic converter is used, which can adsorb NOx at low temperatures of 150 ° C. or less.

In a further embodiment of the method, in the case of thermal desorption of nitrogen oxides from the NOx storage catalytic converter, after the internal combustion engine has been switched off in the exhaust gas flow direction, an ammonia-containing reducing agent is fed to the exhaust gas cleaning system upstream of the at least one SCR-catalytically active exhaust gas cleaning component. In this way, NOx desorbed from the NOx storage catalytic converter _{can be reduced to harmless N 2} by the SCR-catalytically active exhaust gas cleaning component arranged downstream of the NOx storage catalytic converter, and its release to the environment can be avoided. In this case, it is preferably provided that, when the heating element begins to be heated, air is blown into the exhaust gas cleaning system by means of a conveying device in front of the heating element. This avoids overheating of the heating element and ensures that desorbing NOx is conveyed to the SCR-catalytic exhaust gas cleaning component.

In a further embodiment of the method, a maintenance heating mode is provided for at least approximately maintaining the operating temperatures of the exhaust gas cleaning components, in which at least one heating measure for heating the exhaust gas cleaning system is taken in a predeterminable manner from a selection list of heating measures.

In normal operation without heating measures, a continuous check is preferably carried out to determine whether there is a critical condition in that one of the exhaust gas cleaning components threatens to cool down undesirably. In order to keep the exhaust gas cleaning components, which are typically at least approximately at operating temperature, in this state during normal operation, a heating measure is selected in a predefinable manner from a selection list stored in the control device and taken. The selection is preferably made on the basis of an associated additional fuel consumption and / or on the basis of a possibly associated increase in emissions, in particular the raw NOx emissions, with attention always being paid to the minimum possible total emissions.

In a further advantageous embodiment of the method, the heating measure is selected in such a way that, especially in normal operation, it is continuously determined for which period of time from the current point in time an operation of the exhaust gas cleaning system with exhaust gas cleaning components heated at least approximately to operating temperature is likely to be possible without taking an additional heating measure. If this time span falls below a predefinable time span limit, then that heating measure is selected from the selection list of heating measures or those heating measures are selected with which or with which the time span for the operation of the exhaust gas cleaning system with exhaust gas cleaning components heated at least approximately to the operating temperature is likely to be at least around a predeterminable value extended. The predictions are made using a prediction model stored in the control unit. It is thus possible to react in advance to operating conditions that are changing or developing in an unfavorable manner and to ensure at least adequate exhaust gas cleaning.

In a still further embodiment of the invention, the heating measure or the heating measures of the selection list are selected depending on a charge state of a battery coupled to the electric motor and depending on an estimated resulting additional fuel consumption and / or an estimated resulting increase in raw pollutant emissions in such a way that the smallest possible Additional fuel consumption and / or the smallest possible Increase in raw pollutant emissions. This enables fuel consumption and emissions behavior to be optimized so that the minimum possible total emissions are always shown

In a further embodiment of the method, a first coolant circuit for temperature control of the internal combustion engine is operated with a first electrical coolant pump and a second coolant circuit, which is separate from this, for temperature control of the electric motor is operated with a second electrical coolant pump, the first coolant pump with a higher electrical one compared to the second coolant pump Operating voltage is operated. The first coolant pump is preferably designed to be more powerful and throughput than the second coolant pump. A power supply adapted for this purpose enables optimal component design. The first coolant pump is preferably connected to the traction battery, while the second coolant pump is connected to an on-board battery for the operation of small consumers.

In a further embodiment of the method, a minimum coolant flow rate is determined for the first and / or the second coolant circuit, and a speed of the first and / or the second coolant pump compared to a respective nominal speed may be reduced depending on operating parameters of at least the drive system to set the minimum coolant flow rate. A speed reduction preferably takes place mainly as a function of the speed of the internal combustion engine or of the electric motor and / or as a function of the respective coolant temperature. Any speed reduction can also take place as a function of one or more of the following variables: ambient temperature, oil sump temperature, a temperature in the low-pressure exhaust gas recirculation branch, a cylinder head temperature, the operation of an interior air conditioning system, a temperature of a reducing agent metering valve that may be connected to one of the coolant circuits.

• 1 eine schematische Darstellung eines Antriebssystems mit angeschlossenem Abgasreinigungssystem für das erfindungsgemäße Hybridfahrzeug,
• 2 eine schematische Darstellung einer ersten vorteilhaften Ausführungsform eines Abgasreinigungssystems für das erfindungsgemäße Hybridfahrzeug,
• 3 eine schematische Darstellung einer zweiten vorteilhaften Ausführungsform eines Abgasreinigungssystems für das erfindungsgemäße Hybridfahrzeug,
• 4 eine schematische Darstellung eines Kühlmittelkreislaufsystems für das erfindungsgemäße Hybridfahrzeug, und
• 5 ein Blockdiagramm zur schematischen Darstellung von Grundzügen des erfindungsgemäßen Betriebsverfahrens.

The above and further features and advantages of the invention emerge from the following description of preferred, non-limiting exemplary embodiments of the invention with reference to the accompanying drawings. Show in it:

• 1 a schematic representation of a drive system with a connected exhaust gas cleaning system for the hybrid vehicle according to the invention,
• 2 a schematic representation of a first advantageous embodiment of an exhaust gas purification system for the hybrid vehicle according to the invention,
• 3 a schematic representation of a second advantageous embodiment of an exhaust gas cleaning system for the hybrid vehicle according to the invention,
• 4th a schematic representation of a coolant circuit system for the hybrid vehicle according to the invention, and
• 5 a block diagram for the schematic representation of the main features of the operating method according to the invention.

This in 1 summarized with the reference number 1 The drive system of the hybrid vehicle according to the invention, which is referred to only as an example and shown schematically, comprises an internal combustion engine as drive units 2 as well as an electric motor 3 . The internal combustion engine, preferably designed as a diesel engine 2 is about a clutch 4th to a transmission 5 connected. The electric motor 3 is also to the gearbox 5 connected and can just like the internal combustion engine 2 Drive power via the gearbox 5 and an outgoing drive shaft 6th to the wheels of the hybrid vehicle. This is done in the case of the internal combustion engine 2 This fuel is supplied to this via a fuel supply system (not shown) in its combustion chambers (also not shown), where it is burned and mechanical energy is generated in the process. The electric motor 3 is connected to a traction battery, not shown, to generate kinetic energy or drive power.

With the clutch open 4th only the electric motor can do 3 Drive power via the gearbox 5 and the outgoing drive shaft 6th to the wheels of the hybrid vehicle. Conversely, when the hybrid vehicle is overrun, its kinetic energy can be generated by the electric motor, which can also be operated as a generator 3 converted into electrical energy and fed into the traction battery and thus charged.

When the clutch is closed 4th the internal combustion engine can, too 2 Drive power via the gearbox 5 and the outgoing drive shaft 6th to the wheels of the hybrid vehicle. When the hybrid vehicle is overrun, the internal combustion engine 2 be towed and thus absorb kinetic energy of the hybrid vehicle. On the other hand, it can also be provided that the internal combustion engine 2 mechanical energy delivered to the electric motor 2 is transmitted and used by this in generator mode to charge the traction battery.

Through the operative connections provided for the hybrid vehicle according to the invention between the engines 2 , 3 on the one hand and between the drive wheels of the hybrid vehicle and the motors 2 , 3 on the other hand, the hybrid vehicle can use both the internal combustion engine 2 alone, as well as from the electric motor 3 alone, as well as be driven by both motors 2, 3 in a predefinable power distribution. It is also possible that when the hybrid vehicle is overrun, its kinetic energy is partially transferred to the internal combustion engine 2 alone or the electric motor 3 alone or in a predeterminable distribution between both engines 2 , 3 is transmitted.

The internal combustion engine is used to burn fuel 2 Combustion air from the environment via an air supply line 11 . The throughput of the combustion air can be adjusted by means of an in the air supply line 11 arranged adjustable intake air throttle 14th may be throttled. The exhaust gas resulting from the fuel combustion is via an exhaust pipe 20th and an exhaust gas purification system disposed therein 10 derived. The exhaust gas cleaning system 10 has an electrical heating element and, downstream of it, several exhaust gas purification components serving in particular for NOx removal, which will be discussed in more detail below.

Upstream of the exhaust gas cleaning system, viewed in the exhaust gas flow direction 10 is a turbine 9 of an exhaust gas turbocharger 7th arranged, which has an associated compressor 8th in the air supply line 11 can drive. The turbine 9 is in the present case designed as a turbine with variably adjustable blade position.

The combustion air can be exhaust gas via a low-pressure exhaust gas recirculation line (LP EGR line) 12th as well as a high pressure exhaust gas recirculation line (HP EGR line) 15th are mixed in. The LP EGR line branches off from the exhaust gas cleaning system 10 off, the HP-EGR line 15th branches in front of the turbine 9 from the exhaust pipe 20th from.

The amount of over the LP EGR line 12th Admixed exhaust gas can via an between intake air throttle 14th and compressor 8th arranged adjustable LP EGR valve 13th can be set. The amount of over the HP EGR line 15th admixed exhaust gas can be via a behind the compressor 8th in the air supply line 11 arranged, adjustable HP EGR valve 16 can be set. However, a common EGR valve can also be used for the HP EGR line 15th and the LP-EGR line 12th be provided. Preferably both in the LP-EGR line 12th as well as in the HP-EGR line 15th in each case a cooler, which may also be designed to be bypassed, is provided for recirculated exhaust gas, which is not shown separately here. The LP EGR valve 13th however, it is not absolutely necessary.

To control the operation of the internal combustion engine 2 and electric motor 3 as well as for controlling the EGR valves 13th , 16 , the intake air throttle 14th and the turbine 9 a control unit is provided which is connected to the components to be controlled by control lines, which is not shown in detail. Also not shown is a gas delivery device, which is particularly useful when the internal combustion engine is not running 2 and energized heating element, a gas, in particular air, upstream of the heating element of the exhaust gas cleaning system 10 can feed.

As for the emission control system 10 relates, a first advantageous embodiment is shown schematically in FIG 2 shown. This emission control system 10 points in the exhaust pipe 20th in the main exhaust gas flow direction 21 seen one behind the other in this order an electrical heating element 22nd and a NOx storage catalytic converter as the exhaust gas purification component as the first exhaust gas purification component which is effective in terms of oxidation catalysis 23 , a first SCR-catalytically effective exhaust gas cleaning component, a second SCR-catalytically effective exhaust gas cleaning component 25th , as well as an oxidation catalytic converter as a second exhaust gas cleaning component with an oxidative catalytic effect 26th on. Here are the electrical heating element 22nd and the NOx storage catalytic converter 23 are arranged closely adjacent to one another in a common housing, this housing being close to the combustion engine, preferably directly on the turbine 9 ( 1 ) is flanged, mounted. The second SCR-catalytically active exhaust gas cleaning component is also closely adjacent in a common housing, but preferably remote from the combustion engine in an underbody area of the hybrid vehicle 25th and the oxidation catalyst 26th arranged. The first SCR-catalytically effective exhaust gas cleaning component is also present in a separate housing close to the combustion engine

In the exhaust gas flow direction 21 seen before the second SCR catalytically active exhaust gas cleaning component 25th branches off an LP EGR line 12th from which exhaust gas from the exhaust pipe 20th and the combustion air for the internal combustion engine 2 can be admixed.

The electrical heating element designed as a resistance heater 22nd preferably has a winding or folding of metal foils through which exhaust gas can flow. Will the heating element 22nd Supplied with electricity from the traction battery, the metal foils and the exhaust gas flowing around them heat up. This in turn allows heat to reach the downstream exhaust gas cleaning components 24 , 25th , 26th and in particular be transferred to the NOx storage catalytic converter 23.

In the present case, the NOx storage catalytic converter 23 is designed as a ceramic honeycomb body with a coating (but can also be a metallic honeycomb body) which, when in contact with especially lean exhaust gas, binds NOx contained therein by chemisorption and / or physisorption and can thus remove it from the exhaust gas. In addition, the coating has an oxidation-catalytic effect. The process of NOx uptake begins at around 150 ° C at a noticeable rate and runs steadily faster up to around 350 ° C with increasing temperature. However, as the amount of absorbed NOx increases, the storage capacity of NOx decreases. NOx then increasingly slips through the NOx storage catalytic converter 23, with more or less large proportions of the predominantly nitrogen monoxide (NO) in the exhaust gas of the internal combustion engine as a function of the temperature 2 contained NOx are oxidized to nitrogen dioxide (NO _2). However, this typically improves the NOx conversion by the downstream SCR-catalytically active exhaust gas cleaning _{components, which can typically convert NOx with larger NO 2} proportions particularly efficiently. In order to restore the NOx absorption capacity of the NOx storage catalytic converter 23 when saturation has occurred, it can be regenerated, for which purpose rich exhaust gas, ie exhaust gas with a reducing effect, is applied to it by the internal combustion engine. Stored NOx is desorbed with reduction to nitrogen (N2) and discharged with the exhaust gas. However, stored NOx can also be thermally desorbed at high temperatures of more than approximately 400 ° C to 450 ° C.

The first SCR-catalytically effective exhaust gas cleaning component is present as a particle filter 24 with an SCR-catalytically active coating, hereinafter referred to simply as SDPF, formed. Due to this design, the SDPF 24 both filter out particles, in particular soot particles, from the exhaust gas, and catalytically reduce NOx contained in the exhaust gas to harmless N _{2 by reduction with ammonia (NH 3} ) contained in the exhaust gas. This SCR-catalytic effectiveness starts at around 150 ° C and increases rapidly with increasing temperature.

The second SCR catalytically effective exhaust gas cleaning component 25th is presently designed as an SCR catalytic converter in the form of a honeycomb body. With regard to the SCR-catalytic effectiveness, the SDPF described above is referred to 24 referenced.

The oxidation catalyst 26th is mainly used for the oxidative removal of NH ₃ , which may be caused by the SCR catalytic converter 25th slips. However, other reducing components such as HC or CO can also be catalytically oxidized.

To get the SDPF 24 and the SCR catalytic converter 25th A first metering valve must be supplied _{with NH 3 in} order to develop its SCR-catalytic effect 29 input side of the SDPF 24 and a second metering valve 32 input side of the SCR catalytic converter 25th in the exhaust pipe 20th assembled. With these independently operable dosing valves 29 , 32 can the exhaust gas, an NH ₃ contained in free or bound form reducing agent is added in measured doses. In the present case, aqueous urea solution is used as the reducing agent (but it can also be gaseous NH3), which feeds the metering valves from a tank via separate pumps 29 , 32 can be supplied, which is not shown in detail.

There are various sensors in the exhaust pipe to measure temperatures and pollutant concentrations in the exhaust gas 20th installed. A first temperature sensor is present 27 on the input side of the electrical heating element 22nd and a second temperature sensor 30th input side of the SDPF 24 intended. There is also a third temperature sensor 33 input side of the SCR catalytic converter 25th and a fourth temperature sensor 34 on the outlet side of the oxidation catalytic converter 26th intended. There is also a first NOx sensor 28 on the input side of the SDPF 24 and a second NOx sensor 31 on the output side of the SDPF 24 and before the branch of the LP-EGR line 12th intended. The second NOx sensor 31 can, however, also downstream of the branch of the LP-EGR line 12th and before the SCR catalytic converter 25th installed, but it must be positioned in front of the second urea dosing point. Another, third NOx sensor 35 is on the output side of the oxidation catalytic converter 26th intended. Using the temperature sensors 27 , 30th , 33 , 34 and the NOx sensors 28, 31, 35 is a comprehensive monitoring of the temperature and NOx content of the exhaust gas within the exhaust gas purification system 10 and the performance of the exhaust gas cleaning components built into it. For this purpose, the sensors are connected to a control unit, not shown, which can evaluate the corresponding signals.

In 3 is a further advantageous embodiment of the exhaust gas cleaning system 10 shown, the corresponding components, as far as they are with the parts of 1 or. 2 match, are identified by the same reference numerals. This in 3 The exhaust gas cleaning system shown has a similar structure to the exhaust gas cleaning system 10 of the 2 , which is why only the differences are discussed below.

In contrast to the in 2 The embodiment illustrated has the exhaust gas purification system of 3 the first SCR catalytically effective exhaust gas cleaning component is a combination of an SDPF 24 and an SCR catalytic converter 36 on which are closely spaced in a common Housing are arranged. The present is the SDPF 24 in exhaust gas flow direction 21 seen in front of the SCR catalytic converter 36 arranged. However, the reverse sequence can also be provided.

In 4th a preferred coolant circuit system of the hybrid vehicle according to the invention is only shown schematically. Insofar as the components shown therein correspond to those in the preceding figures, the same reference symbols are used. The coolant circuit system of 4th has a first coolant circuit 40 and a second coolant circuit which is separate therefrom 47 on. The first coolant circuit 40 mainly used to cool the internal combustion engine 2 , whereas the second coolant circuit 47 mainly the cooling of the electric motor 3 serves. A cooling of the by the internal combustion engine 2 The heated coolant can pass through a first heat exchanger through which air can flow 54 take place in the first coolant circuit 40 is arranged. A second heat exchanger is used in the same way 57 in the second coolant circuit 47 the cooling of by the electric motor 3 heated coolant. As explained in more detail below, the coolant circuits 40 , 47 Branch circuits, which are used for cooling or temperature control of other components. In addition, there are compensating and degassing tanks 58 , 59 provided, which in particular temperature-related volume fluctuations of the coolant in the coolant circuits 40 , 47 can intercept.

For conveying the coolant in the first coolant circuit 40 is a first electric coolant pump 50 provided, the second coolant circuit 47 has a second electric coolant pump for this purpose 51 on. The first coolant pump 50 is connected to the traction battery with a nominal voltage of 48 V, for example, while the second coolant pump, which is less powerful and throughput, is less 51 is connected to a 12 V on-board battery. The coolant pumps 50 , 51 can be operated with speed control in a predeterminable manner, for example by reducing the operating voltages. This allows the coolant throughputs in the coolant circuits 40 , 47 can be adjusted as required.

In the first coolant circuit 40 the internal combustion engine 2 supplied coolant is discharged from this and can be in a first branch circuit 41 a third heat exchanger serving for interior heating 56 flow through. Further can in a second branch circuit 44 the HP EGR valve 16 flowed through and thus tempered. A third branch circuit 45 is used for lubricant temperature control, for which an oil cooler 53 coolant flows through it. Furthermore, there is a fourth branch circuit indicated by a dashed line 42 provided in which a fourth heat exchanger 55 is arranged, which is used to control the temperature of the LP-EGR line 12th Recirculated exhaust gas is used. Another fifth branch circuit, indicated by a dashed line 43 of the first coolant circuit 40 is used to control the temperature of the first metering valve 29 . For this fifth cycle of branches 43 is a separate third coolant pump 60 intended. This enables one of the coolant throughput of the first coolant circuit 40 largely independent adjustment of the coolant flow rate in the fifth branch circuit 43 . Preferably the third coolant pump is 60 connected to the 12 V on-board battery. By means of the first heat exchanger 54 immediate bypass line 46 and a control valve preferably designed as a three-way valve 61 can be the coolant throughput through the first heat exchanger 54 and thus the cooling effect caused by it can be specifically influenced. In addition, the coolant throughput is influenced in particular by the first branch circuit 41 , the second branch circuit 44 and the third branch circuit 45 enables.

In the second coolant circuit 47 for the electric motor 3 a branch circuit is also provided. This sixth branch circuit 48 is used to control the temperature of the HP-EGR line 15th recirculated exhaust gas, for which a fifth heat exchanger 52 is provided.

The following is based on 5 went into the basics of the operating method according to the invention. Reference is also made to the previous figures. In the block diagram of 5 Solid connecting lines indicate transitions from operating states shown in the form of blocks. Connection lines drawn in dashed lines indicate data and operational connections of control unit function blocks. To explain the operating method, it is assumed below, without restricting the generality, that the internal combustion engine 2 of the hybrid vehicle is turned off or is in an unfired state with no fuel supply. The previous shutdown is through the status block 65 shown. In this state, the vehicle can either stand still or be in a driving mode.

It is determined that the internal combustion engine will shortly start 2 occurs, temperatures in the exhaust gas cleaning system 10 determined. When the vehicle is parked, it can be determined, for example by recognizing that the door lock has been actuated, that the internal combustion engine will shortly be started 2 he follows. In this case, temperatures in the exhaust gas cleaning system are preferably set after the control unit has been initialized 10 determined. When driving and during brief interruptions in start-stop operation, the Internal combustion engine 2 preferably the temperatures in the exhaust gas cleaning system anyway 10 determined. The temperature can be determined, for example, by evaluating measured values from the sensors installed there. If it is determined that the temperature has fallen below one or more specifiable temperature limit values, a with the status block 66 marked preheating operation is set as the first heating phase of a general heating operation. A temperature limit value can be fallen below, for example, if the temperature of the NOx storage catalytic converter 23 is below a predeterminable temperature of 150 ° C., for example. The heating element is in preheating mode 22nd , preferably starting with a nominal current strength, energized. At the same time there is air in front of the heating element 22nd into the exhaust pipe 20th blown in. The air can be blown in by a suitable conveying device such as a secondary air pump. Depending on the temperature profile over time in the exhaust gas cleaning system 10 can especially in preheating mode 66 a continuous or other decrease in the heating power of the heating element 22nd , for example, be provided by a pulse-width modulated power supply. The settings of the preheating operation 66 are in the present case of a particular to control the heating of the exhaust gas cleaning system 10 provided first control module 71 of the control unit. An interruption of the preheating operation can also be provided, for example when a secondary air pump for blowing in air has reached a predetermined limit running time and is threatened with overheating. After the secondary air pump has cooled down sufficiently, preheating can be started with the heating element supplied with current 22nd and air injection can be resumed. If possible, the preheating mode is used 66 continued at least until the NOx storage catalytic converter 23 has at least approximately reached a predeterminable temperature of approximately 200 ° C. or its light-off temperature, at least on the inlet side.

Used before starting the internal combustion engine 2 found that one for starting preheating 66 the relevant lower temperature limit is not fallen below, the operating state of the preheating mode 66 are skipped and the internal combustion engine 2 without preheating the emission control system 10 to be started.

With starting the combustion engine 2 if this goes into a fired operation, which is done by the status block 67 is marked. Was previously the preheating mode 66 active, the heating of the heating element is activated 22nd preferably not by starting the internal combustion engine 2 interrupted. Preferably the heating element 22nd energized with nominal amperage until a predeterminable temperature in the exhaust gas cleaning system 10 is reached and then the heating power is reduced in a predeterminable manner. The heating element has proven to be advantageous 22nd to be heated at nominal power until at least a first zone of the NOx storage catalytic converter 23 has reached a predeterminable temperature of, for example, 200 ° C. However, another temperature can also be used in the exhaust gas cleaning system 10 are used as authoritative.

After the internal combustion engine has run steadily 2 and preferably a predeterminable speed limit, the air injection by the conveying device can be terminated and a through the block 68 marked warm-up operation started as a second warm-up phase, provided that one or more specifiable temperature limit values are specifically in the exhaust gas cleaning system 10 have fallen below. This is particularly the case when one or more of the exhaust gas cleaning components 23 , 24 , 25th , 26th , 36 are below their operating temperature. If this is not the case, the heating-up mode can be used 68 be skipped. Is the heating mode 68 carried out, this is also carried out by the first control module with its settings explained in more detail below 71 controlled by the control unit.

In heating mode 68 on the one hand becomes the heating element 22nd preferably heated with a fraction of the nominal power and thus the exhaust gas cleaning system 10 further heated. The heating output is preferably initially set as a function of the temperature and the NOx loading of the NOx storage catalytic converter 23. These can be model-based taking into account the temperature from the first temperature sensor 27 provided temperature value and the operating conditions of the internal combustion engine 2 be determined. If the NOx storage catalytic converter 23 has reached a predeterminable temperature, which can be based on the ability to store NOx or to form NO ₂ , then it is preferably provided that the heating power of the heating element is increased 22nd as a function of the temperature of the first SCR-catalytic exhaust gas cleaning component 24 adjust. Once this has reached its operating temperature, the heating output is preferably set as a function of the temperature of the second SCR-catalytically active exhaust gas cleaning component 25th .

On the other hand, the internal combustion engine 2 initially operated in a first heating mode. In this first heating operating mode, there is an early post-injection of fuel into the combustion chambers of the internal combustion engine, which is provided in addition to the main injection 2 performed. This preferably takes place at such an early point in time after the main injection that the post-injected fuel burns at least largely in the respective combustion chamber. It is therefore a so-called co-burning one Post injection with torque generation. It preferably takes place in a crank angle range of 20 ° to 40 ° after top dead center. This generates particularly hot exhaust gas, which causes the exhaust gas cleaning system 10 in connection with that of the heating element 22nd applied heating effect can be heated quickly. In the first heating mode, the internal combustion engine is operated without low-pressure exhaust gas recirculation. A specifiable exhaust gas recirculation rate is set in a regulated manner for the high pressure exhaust gas recirculation. There is also a regulated setting of the blade positions of the turbocharger turbine 9 as well as the intake air throttle 14th . The internal combustion engine is in the first heating mode 2 also operated in such a way that the exhaust gas mass flow it emits does not exceed a specifiable upper exhaust gas mass flow limit. In this way, if necessary, more or less catalytically active exhaust gas cleaning components are protected from being overloaded with pollutants to be removed. Provision is therefore made for the upper exhaust gas mass flow limit as a function of a temperature and / or a performance already achieved by one or more of the exhaust gas cleaning components 23 , 24 , 25th , 26th , 36 to pretend. The internal combustion engine can also be provided 2 to be controlled so that a predefinable lower exhaust gas mass flow limit is not undershot. Preferably, an exhaust gas mass flow range is predefined that increases with increasing heating of the exhaust gas cleaning system 10 is enlarged. It is also advantageous if the upper exhaust gas mass flow limit as a function of an upper temperature limit and / or the lower exhaust gas mass flow limit as a function of a lower temperature limit for one or more of the exhaust gas cleaning components 23 , 24 , 25th , 26th , 36 is determined.

The respective exhaust gas mass flow limit is preferably set by setting one of the internal combustion engine 2 delivered torque. In the case of an intended upper exhaust gas mass flow limit, this is done by the internal combustion engine 2 output torque is limited to a value corresponding to the upper exhaust gas mass flow limit. If the driver of the vehicle requests a torque that exceeds this torque limit, the electric motor is activated 3 accordingly energized to deliver the additionally requested torque. If a lower exhaust gas mass flow limit is not to be undershot and the driver only requests a correspondingly insufficient torque, this can be done by the internal combustion engine 2 given excess torque can be used to charge the traction battery. The internal combustion engine drives this 2 the electric motor switched to a generator mode 3 accordingly.

Used in heating mode 68 the light-off temperature of the SDPF 24 or the light-off temperature of the SCR catalytic converter 36 of typically about 150 ° C is reached or exceeded, the first metering valve 29 actuated to deliver a predeterminable amount of reducing agent.

Used for one or more of the emission control components 23 , 24 , 25th , 26th , 36 a predefinable temperature limit is reached while the heating element continues to be energized 22nd the operation of the internal combustion engine 2 switched to a second heating mode. A temperature limit relevant for this can be given, for example, by a temperature of the NOx storage catalytic converter 23 of approximately 200 ° C. Switching to the second heating operating mode can also take place when the NOx storage catalytic converter has reached a temperature at which an efficiency for NOx storage or for NO ₂ formation is at least approximately maximum.

In the second heating operating mode, a late post fuel injection is provided in addition to or instead of the early post fuel injection. This is carried out as a so-called non-co-burning and possibly low-torque post-injection at a crank angle of about 150 ° C. after top dead center. There remains an excess of oxygen from the combustion engine 2 discharged exhaust gas preferably obtained. In this way, the exhaust gas from the internal combustion engine 2 Enriched with unburned fuel components. These can be oxidized on the NOx storage catalytic converter 23, which is already active for oxidation, due to the lean exhaust gas, with further release of heat. Accordingly, the heating power of the heating element 22nd be reduced to a lower specifiable value.

A limitation or restriction of the exhaust gas mass flow is preferably retained. However, compared to the first heating operating mode, changed values can be provided for the upper and / or the lower exhaust gas mass flow limit. The same applies to the high-pressure exhaust gas recirculation, the turbocharger and intake air throttle settings. The exhaust gas mass flow limit values are set, as described above, as a function of a temperature and / or a performance that has already been achieved by one or more of the exhaust gas cleaning components 23 , 24 , 25th , 26th , 36 .

Reaches or exceeds in heating mode 68 the second SCR catalytically effective exhaust gas cleaning component 25th a predeterminable temperature of about 150 ° C, the second metering valve 32 actuated to deliver a predeterminable amount of reducing agent.

Do the emission control components 23 , 24 , 25th , 26th , 36 reaches its operating temperature, the metering valves inject 29 , 32 Volume-controlled urea solution in the exhaust gas. In this case, normal operation becomes 69 recorded.

In normal operation 69 are the heating measures of the heating-up operation 68 deactivated. That is, the heating element 22nd is switched off and an early or late fuel post-injection does not take place. In addition to the regulated high pressure exhaust gas recirculation, a regulated low pressure exhaust gas recirculation is activated. There is also a regulated setting of the blade position of the exhaust gas turbocharger turbine 9 . The throttling effect of the intake air throttle 14th can be done by a map control. In the present case, one takes over in particular for normal operation 69 provided second control module 72 the control unit controls and adjusts the operating parameters. The second control module 72 the internal combustion engine 2 so that it is operated either in an operating mode that is minimized with regard to the specific fuel consumption or in an operating mode that is minimized with regard to the raw NOx emissions in order to always be able to guarantee the minimum possible total emissions. According to the invention, this takes place as a function of determined NOx emission values for the exhaust gas emitted to the environment within a predeterminable previous period or a previous driving distance or depending on estimated NOx emission values of an upcoming period or an upcoming driving distance. The relevant NOx emission value or the relevant NOx emission values are preferably determined in a separate NOx emission determination module 73 the exhaust gas emitted to the environment is determined in a predefined route and / or journey time that was past the current point in time. For example, the last 3 km or 6 km or the distance covered since the combustion engine was last started can be taken into account as the distance traveled. If a computational model is used to determine a distance-related or time-related total NOx emission value, the determination is made, for example, on the basis of stored characteristics or maps for the NOx conversion efficiencies of the NOx storage catalytic converter 23 and the SCR-catalytically effective exhaust gas cleaning components of the exhaust gas cleaning system 10 , the total exhaust gas mass flow and the operating point-dependent raw NOx emissions of the internal combustion engine 2 . In this case, it is preferably provided that dependencies of the NOx conversion efficiencies on temperature, exhaust gas throughput and aging status are kept in the characteristic curves or characteristic maps. NOx emission sum values determined on the basis of a model can be corrected or made plausible by comparison with a via the measured values of the third NOx sensor 35 at the end.

In the present case, the NOx emission determination module 73 sends the ascertained NOx sum value or the ascertained NOx sum values to the second control module 72 . If a predeterminable NOx emission limit for one or more of the determined NOx sum values is reached or exceeded, the second control module switches 72 the internal combustion engine 2 in a normal operating mode with minimized raw NOx emissions in order to always be able to guarantee the minimum possible total emissions. In the other case, a normal operating mode with minimized specific fuel consumption is set.

Using the in the exhaust gas cleaning system 10 built-in temperature sensors 27 , 30th , 33 , 34 the temperatures of the exhaust gas cleaning components are continuously monitored, especially during normal operation. In the present case, this takes place in a temperature determination module assigned to the control device 75 . According to the invention, the monitoring includes a model-based computational evaluation in relation to a further expected future temperature profile. If it is determined that one or more of the emission control components 23 , 24 , 25, 26, 36 fall below their operating temperature or, depending on the temperature, a specifiable performance capability within a specifiable time span from the current point in time, this is communicated to the second control module 72 of the control unit. The second control module 72 then sets operating conditions of a maintenance heating operation 70 on.

In maintenance heating mode 70 one or more heating measures are selected and set from a selection list of possible heating measures. In this case, the heating measure or the heating measures are selected with the proviso that when they are taken, the operation of the exhaust gas purification components with at least an approximate operating temperature is extended by at least a predeterminable period of time. Furthermore, from the possible combination of heating measures that may result, that one is selected which results in the smallest possible increase in fuel consumption and / or in the NOx emissions emitted to the environment. If a predeterminable total NOx emission value for a specific distance covered or driving time is exceeded, this is preferably the one Heating measure selected for which the smallest possible increase in NOx emissions results. It is advantageous if the total NOx values determined in the NOx emission determination module 73 are also transferred to the maintenance mode 70 controlling third control module 74 be transmitted. On the other hand, it is preferably provided that in the temperature determination module 75 determined results of the continuous temperature monitoring also to the third control module 74 be transmitted. In this way it can be determined whether the heating measure or heating measures taken achieve the desired effect, in particular with regard to the exhaust gas cleaning components remaining at operating temperature for a longer period of time. There will be a further drop in temperature or performance of one or more of the emission control components 23 , 24 , 25, 26, 36 detected or forecast, a further heating measure can be selected from the selection list and switched on. On the other hand, the heating measure can be reduced or switched off if it is determined that the exhaust gas cleaning components can probably be kept at operating temperature for long enough anyway.

When selecting a heating measure, the charge status of the traction battery is preferably also taken into account. A heating measure reducing the state of charge of the battery is not taken if the state of charge falls below a predeterminable lower limit value or if this would be undershot as a result of the heating measure. On the other hand, a heating measure that increases the state of charge of the battery is not taken if the battery is already fully or almost fully charged.

• - Bestromung des Heizelements 22 mit vorgebbarer Heizleistung
• - Frühe Kraftstoffnacheinspritzung
• - Späte Kraftstoffnacheinspritzung
• - Erhöhung der vom Verbrennungsmotor abgegebenen mechanischen Leistung.

The selection list for those in maintenance heating mode 70 Measures to be taken can include at least the following heating measures.

• - energization of the heating element 22nd with specifiable heating power
• - Early post fuel injection
• - Late post fuel injection
• - Increase in the mechanical power output by the internal combustion engine.

In the latter case, one of the electric motor 3 output drive power in favor of the combustion engine 2 output drive power can be reduced. Carries the electric motor 3 does not contribute to vehicle propulsion, a portion of the combustion engine that is not required for vehicle propulsion can 2 generated drive power to the electric motor running in generator mode 3 can be transferred and used to charge the traction battery.

Is used after the heating measure or measures have been taken, for example in the temperature determination module 75 found that the temperatures of the exhaust gas cleaning components have risen again to such an extent that normal operation is likely to be possible again over a predeterminable period of time without additional heating measures, so the state of maintenance heating operation 70 finished and back to normal operation 69 passed over.

Another measure that reduces the overall energy consumption of the hybrid vehicle can be that an energy-consuming regeneration of the NOx storage catalytic converter 23, which is required from time to time in any case, during the heating-up operation 68 is made or inserted into it. For this purpose, the operation of the internal combustion engine 2 controlled in such a way that at least temporarily an exhaust gas with an overall reducing effect is emitted. This can be done by means of a late fuel injection. An early fuel post-injection can also be provided. At the same time the internal combustion engine 2 operated in such a way that the exhaust gas mass flow it emits lies between a specifiable upper and a specifiable lower exhaust gas mass flow limit. The exhaust gas mass flow limits are preferably a function of one or more temperatures in the exhaust gas cleaning system 10 stored in a map. It is also provided that the internal combustion engine 2 operated with a minimum load of around 3 bar mean pressure. If necessary, the internal combustion engine can do this 2 be operated in such a way that a mechanical excess power that is not required for the vehicle drive is generated via the electric motor running in generator mode 3 is used to charge the traction battery. Conversely, if necessary, that of the internal combustion engine 2 given drive power in favor of one from the electric motor 3 applied drive power can be reduced.

Provision can also be made for an at least partial regeneration of the NOx storage catalytic converter 23 after the internal combustion engine has been switched off 2 to undertake. For this purpose, the heating element is activated immediately after the internal combustion engine has been switched off 22nd energized so that the NOx storage catalytic converter 23 is heated and can thermally desorb stored NOx. This is typically done by means of the heating element 22nd a heating of the NOx storage catalytic converter 23 to a temperature of 400.degree. C. to 450.degree. As a result of the desorption of previously stored NOx, there is a restart of the internal combustion engine 2 an at least partially regenerated NOx storage catalytic converter 23 is available. So is enables NOx to be removed from the exhaust gas very quickly after a restart or cold start.

Simultaneously with the energization of the heating element after switching off the internal combustion engine 2 is air upstream of the heating element by a gas delivery device such as a secondary air pump 22nd into the exhaust pipe 20th blown. This will cause the heating element to burn out 22nd prevented and desorbing NOx is promoted by the downstream SCR-catalytically active exhaust gas cleaning components. The first metering valve is provided so that NOx is not released into the environment 29 and / or the second metering valve 32 to operate to dispense urea solution into the exhaust gas. With the air blown in by the secondary air pump to the SDPF 24 or SCR catalytic converter 25th _{NOx delivered can thus be reduced to harmless N 2} by these SCR-catalytically active exhaust gas cleaning components. If one or all of these components are not at operating temperature, the addition of urea solution can also be omitted. In this case, provision can also be made for the regeneration of the NOx storage catalytic converter 23 by thermal NOx desorption after the internal combustion engine has been switched off 2 to renounce.

For the follow-up phase with regeneration of the NOx storage catalytic converter 23 after the internal combustion engine has been switched off 2 a comparatively short duration of less than about 30 s may be sufficient.

A reduction in fuel consumption can also be achieved through reduced-performance operation of the coolant pumps 50 , 51 be achieved. To explain a preferred procedure, FIG 4th Referenced.

• - Umgebungstemperatur
• - Schmiermittel- bzw. Ölsumpftemperatur
• - Temperatur im Niederdruck-Abgasrückführzweig
• - Zylinderkopftemperatur
• - Innenraum-Klimatisierungseinstellparameter
• - Temperatur erstes Dosierventil 29
• - Drehzahl Verbrennungsmotor 2
• - Drehzahl Elektromotor 3
• - Kühlmitteltemperatur im ersten Kühlmittelkreislauf 40
• - Kühlmitteltemperatur im zweiten Kühlmittelkreislauf 47.

To reduce the power consumption of the first coolant pump 50 and / or the second coolant pump 51 To achieve this, they are possibly operated at a speed that is reduced compared to the nominal speed. This is preferably done as a function of one or more of the following recorded operating parameters (or other):

• - ambient temperature
• - Lubricant or oil sump temperature
• - Temperature in the low-pressure exhaust gas recirculation branch
• - cylinder head temperature
• - Indoor air conditioning setting parameters
• - Temperature of the first metering valve 29
• - Internal combustion engine speed 2
• - Electric motor speed 3
• - coolant temperature in the first coolant circuit 40
• - Coolant temperature in the second coolant circuit 47 .

A minimum coolant throughput for the first coolant circuit is preferably determined as a function of at least one of the listed operating variables 40 and / or the second coolant circuit 47 determined. This can be done, for example, by resorting to previously stored characteristics maps in which a relevant influence of the above-mentioned operating variables is mapped. If the determined minimum coolant throughput is lower than the current throughput, the speed of the corresponding coolant pump is reduced. This results in a lower coolant throughput and a reduced need for electrical power.

Especially for the first coolant circuit 40 can also regulate the coolant flow rate and control its distribution to the branch circuits by actuating the three-way valve 61 be provided. In particular if the temperature of the coolant in the first coolant circuit 40 is still below a target temperature or the internal combustion engine 2 has not yet warmed up sufficiently, the three-way valve will 61 operated so that the first heat exchanger 54 is not flowed through, or at most to a reduced extent, by coolant. Instead, coolant is supplied via the bypass line 46 directed.

As can be seen from the above description, the embodiment and mode of operation according to the invention enable particularly energy-saving and low-emission operation of the hybrid vehicle.

List of reference symbols

1

Drive system

2

Internal combustion engine

3

Electric motor

4th

coupling

5

transmission

6th

drive shaft

7th

Exhaust gas turbocharger

8th

compressor

9

turbine

10

Exhaust gas cleaning system

11

Air supply line

12th

LP EGR line

13th

LP EGR valve

14th

Intake air throttle

15th

HP EGR line

16

HP EGR valve

20th

Exhaust pipe

21

Main exhaust gas flow direction

22nd

Heating element

23

NOx storage catalytic converter

24

First SCR catalytic exhaust gas cleaning component

25th

Second SCR catalytic emission control component

26th

Oxidation catalyst

27

First temperature sensor

28

First NOx sensor

29

First dosing valve

30th

Second temperature sensor

31

Second NOx sensor

32

Second metering valve

33

Third temperature sensor

34

Fourth temperature sensor

35

Third NOx sensor

36

SCR catalytic converter

40

First coolant circuit

41

First branch circuit

42

Fourth branch circuit

43

Fifth branch circuit

44

Second branch circuit

45

Third cycle of branches

46

Bypass line

47

Second coolant circuit

48

Sixth branch circuit

50

First coolant pump

51

Second coolant pump

53

oil cooler

54

First heat exchanger

55

Fourth heat exchanger

56

Third heat exchanger

57

Second heat exchanger

58

surge tank

59

surge tank

60

Third coolant pump

61

Control valve

65

Status block switch off combustion engine

66

Preheating status block

67

Internal combustion engine start status block

68

Status block heating-up mode

69

Status block normal operation

70

Status block maintenance heating mode

71

First control module

72

Second control module

73

NOx emissions detection module

74

Third control module

75

Temperature detection module

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102014223490 A1 [0002]

Claims (19)

Hybrid motor vehicle, with a drive system (1) having an internal combustion engine (2) and an electric motor (3), comprising - an exhaust gas purification system (10) connected to the internal combustion engine (2) of the vehicle with an electrical heating element (22) and several exhaust gas purification systems, In particular with regard to NOx reduction, catalytically active exhaust gas cleaning components and - a control device for controlling the operation of the drive system (1) and the exhaust gas cleaning system (10), characterized in that the control device is designed to control the operation of the drive system (1) so that an exhaust gas mass flow emitted by the internal combustion engine (2) does not exceed a specifiable upper exhaust gas mass flow limit and / or does not fall below a specifiable lower exhaust gas mass flow limit, at least during a heating operation with energization of the heating element (22) for heating the exhaust gas, the upper exhaust gas mass flow limit and the lower exhaust gas mass flow limit at least one of the exhaust gas components can be specified as a function of a temperature and / or a performance. Hybrid motor vehicle according to Claim 1 , characterized in that the exhaust gas purification system (10), viewed in the flow direction of the exhaust gas emitted by the internal combustion engine (2), arranged one behind the other - the electrical heating element (22), - a first exhaust gas purification component (23) that is effective in terms of oxidation, in particular designed as a NOx storage catalyst, - a first SCR-catalytically effective exhaust gas cleaning component, - a second SCR-catalytically effective exhaust gas cleaning component (25) and - a second oxidation-catalytically effective exhaust gas cleaning component (26), wherein on the input side of the first and the second SCR-catalytically effective exhaust gas cleaning component each have a metering device (29, 32) are provided for introducing an ammonia-containing reducing agent into the exhaust gas. Hybrid motor vehicle according to Claim 1 or 2 , characterized in that the control device is designed to control the operation of the drive system (1) in such a way that an exhaust gas mass flow output by the internal combustion engine (2) does not exceed a predeterminable upper exhaust gas mass flow limit during normal operation (69) without energizing the heating element (22) and / or does not fall below a predeterminable lower exhaust gas mass flow limit if the temperature and / or the performance of the NOx storage catalytic converter (23) and / or the first SCR-catalytically active exhaust gas cleaning component and / or the second SCR-catalytically active exhaust gas cleaning component (25) has a respective prescribable value fall below. Hybrid motor vehicle according to one of the Claims 1 to 3 , characterized in that the control device is designed to control the operation of the drive system (1) in such a way that an exhaust gas mass flow emitted by the internal combustion engine (2) does not exceed a predeterminable upper exhaust gas mass flow limit during normal operation (69) without current being supplied to the heating element (22), when the temperature of the NOx storage catalytic converter (23) and / or of the first SCR-catalytically active exhaust gas cleaning component and / or of the second SCR-catalytically active exhaust gas cleaning component (25) exceed a respective predeterminable value. Hybrid motor vehicle according to one of the Claims 2 to 4th , characterized in that the electrical heating element (22), the NOx storage catalytic converter (23) and the first SCR-catalytically effective exhaust gas cleaning component are arranged in an engine compartment for the internal combustion engine (2), in particular close to the internal combustion engine, and the second SCR-catalytic exhaust gas cleaning component ( 25) and the second exhaust gas cleaning component (26) with an oxidation-catalytic effect are arranged remote from the combustion engine, in particular in an underbody area of the hybrid motor vehicle. Hybrid motor vehicle according to one of the Claims 2 to 5 , characterized in that the first SCR-catalytically active exhaust gas cleaning component is designed as a particle filter (24) with an SCR-catalytically active coating. Hybrid motor vehicle according to one of the Claims 2 to 5 , characterized in that the first SCR-catalytically active exhaust gas cleaning component has a particle filter (24) with an SCR-catalytically active coating and an SCR catalytic converter (36), which are arranged directly one behind the other in a common housing. Hybrid motor vehicle according to one of the Claims 1 to 7th , characterized in that a first coolant circuit (40) for temperature control of the internal combustion engine (2) and a second coolant circuit (47), which is separate therefrom, for temperature control of the electric motor (3) are provided, a first electric coolant pump (40) for the first coolant circuit (40). 50) and a second electrical coolant pump (51) are provided for the second coolant circuit (47), the first coolant pump (50) being connected to a first voltage supply and the second coolant pump (51) being connected to a second voltage supply and the first voltage supply being connected to an im Compared to second power supply provides greater electrical voltage. Hybrid motor vehicle according to Claim 8 , characterized in that the control device is designed to operate the first and / or the second coolant pump (50, 51) in a power-reduced operation with an adjustable reduced speed compared to normal operation. Operating method for operating a hybrid vehicle with a drive system (1) comprising an internal combustion engine (2) and an electric motor (3) and an exhaust gas cleaning system (10) connected to the internal combustion engine (2) of the vehicle with an electrical heating element (22) and several used for exhaust gas cleaning , in particular with regard to a NOx reduction catalytically active exhaust gas purification components and a control device for controlling an operation of the drive system (1) and exhaust gas purification system (10), wherein - A heating operation is provided for heating the exhaust gas purification system (10) to operating temperature, comprising a first heating phase (66) in which the electric heating element (22) is energized when the internal combustion engine is unfired in such a way that a temperature of a downstream of the heating element (22) in the exhaust gas purification system (10) arranged exhaust gas purification component reaches or exceeds a predeterminable temperature limit and a second heating phase (68) with fired operation of the internal combustion engine, in which the electrical heating element (22) continues to be energized and for the internal combustion engine (2 ) an early and / or a late post fuel injection are provided and the operation of the drive system (1) is controlled in such a way that an exhaust gas mass flow emitted by the internal combustion engine (2) does not exceed a specifiable upper exhaust gas mass flow limit and / or does not fall below a specifiable lower exhaust gas mass flow limit strides, - A normal operation (69) is provided with exhaust gas cleaning components heated at least approximately to operating temperature, in which the internal combustion engine (2) is operated in a first operating mode with a minimized raw NOx emission or in a second operating mode with a minimized specific fuel consumption. Operating procedures according to Claim 10 , characterized in that in an exhaust gas purification system (10) which, viewed in the flow direction of the exhaust gas emitted by the internal combustion engine (2), is arranged one behind the other - the electrical heating element (22), - a first exhaust gas purification component (23) that is effective for oxidation catalysis, in particular designed as a NOx storage catalyst and - has at least one SCR-catalytically active exhaust gas cleaning component, the power supply for heating the heating element (22) is adjusted at least in the second heating phase (68) as a function of a temperature and a NOx loading of the NOx storage catalytic converter (23). Operating procedures according to Claim 11 , characterized in that the NOx storage catalytic converter (23) is regenerated during the second heating phase (68), the internal combustion engine (2) being operated at least temporarily with a rich fuel-air ratio and the operation of the drive system (1) controlled in this way is that an exhaust gas mass flow emitted by the internal combustion engine (2) lies between a specifiable upper and a specifiable lower exhaust gas mass flow limit. Operating procedures according to Claim 11 or 12th , characterized in that immediately after the internal combustion engine (2) has been switched off, the heating element (22) is heated in such a way that the NOx storage catalytic converter (23) is raised to a temperature at which stored nitrogen oxides are at least partially thermally desorbed. Operating procedures according to Claim 13 , characterized in that in the case of thermal desorption of nitrogen oxides from the NOx storage catalytic converter (23) after the internal combustion engine (2) has been switched off in the exhaust gas flow direction (21), an ammonia-containing reducing agent is fed to the exhaust gas cleaning system (10) upstream of the at least one SCR-catalytically active exhaust gas cleaning component becomes. Operating procedure according to one of the Claims 10 to 14th , characterized in that a maintenance heating mode (70) is also provided for at least approximately maintaining the operating temperatures of the exhaust gas cleaning components, in which at least one heating measure for heating the exhaust gas cleaning system (10) is taken in a predeterminable manner from a selection list of heating measures. Operating procedures according to Claim 15 , characterized in that it is determined for which period of time from the current point in time an operation of the Exhaust gas purification system (10) with exhaust gas purification components heated at least approximately to operating temperature is likely to be possible without taking an additional heating measure, and if the period falls below a predefinable time period limit value, that heating measure is selected from the selection list of heating measures or those heating measures are selected with which or with which the The time span for the operation of the exhaust gas purification system (10) with exhaust gas purification components heated at least approximately to operating temperature is likely to be extended by at least a predeterminable value. Operating procedures according to Claim 15 or 16 , characterized in that the heating measure or the heating measures are selected depending on a state of charge of a battery coupled to the electric motor (3) and depending on an estimated resulting increased fuel consumption and / or an estimated resulting increase in pollutant emissions for the heating measures of the selection list in such a way that the smallest possible additional fuel consumption and / or the smallest possible increase in pollutant emissions result. Operating procedure according to one of the Claims 10 to 17th , characterized in that a first coolant circuit (40) for controlling the temperature of the internal combustion engine (2) is operated with a first electrical coolant pump (50) and a second coolant circuit (47), which is separate therefrom, for controlling the temperature of the electric motor (3) with a second electrical coolant pump ( 51) is operated, the first coolant pump (50) being operated with a higher electrical operating voltage compared to the second coolant pump (51). Operating procedures according to Claim 18 , characterized in that a minimum coolant flow rate is determined for the first and / or the second coolant circuit (40, 47) and a speed of the first and / or the second coolant pump (50) for setting the minimum coolant flow rate as a function of operating parameters of at least the drive system (1) , 51) may be reduced in comparison to a respective nominal speed.

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