DE112010002535B4 - MOTOR VEHICLE WITH AN INTERNAL ENGINE AND AN ELECTRIC MOTOR - Google Patents

Abstract

Drive unit, in particular for a motor vehicle, comprising an internal combustion engine (2.1) with at least two combustion chambers (V) in combustion cylinders (2.2), in each of which a fuel-air mixture (starting mixture) is chemically exothermically converted at a time interval in such a way that an exhaust gas mixture is generated with increased latent heat and pressure compared to the starting mixture, with the exhaust gas mixture exerting a compressive force on the pistons (Z) movably mounted in the combustion chambers (V) in such a way that, with the aid of the pistons (Z), an output shaft (2.4) (crankshaft ) is rotated, with a first electromechanical energy converter (G) being mechanically coupled to the output shaft (2.4) of the internal combustion engine (2.1) and exchanging electrical energy with a storage unit for electrical energy (B), and with a further electromechanical energy converter (M / G) is mechanically coupled to at least one wheel shaft (4) of the motor vehicle (1) and likewise everything exchanges electrical energy with the storage unit (B) for electrical energy, the internal combustion engine (2.1) having at least two combustion chambers (V) operated according to a four-stroke process and an expansion cylinder (2.3) acting on the same output shaft, in which from the combustion chambers (V) the exhaust gas mixture pushed out is post-expanded, with the combustion chambers (V) being assigned a further working chamber in the form of the expansion cylinder (2.3), in which the exhaust gas mixture pushed out of the combustion chambers (V) is expanded while delivering mechanical power to the output shaft (2.4). and is subsequently transferred to an exhaust gas outlet (20, 6.1), and second-order inertia forces are balanced by a balancing shaft with balancing masses which is coupled to the output shaft (2.4) via a fixed gear and which is moved at twice the crankshaft speed.

Description

The invention relates to a motor vehicle with an internal combustion engine and at least one electromechanical energy converter, which are used together to propel the motor vehicle, with the internal combustion engine being used most of the time in a particularly efficient operating range or switched off when the motor vehicle is in operation.

State of the art

According to the current status, various systems for motor vehicles with drive systems are available on the market in which at least one internal combustion engine and at least one electric motor are used to drive the respective motor vehicle (so-called hybrid vehicles). In particular, a hybrid system with a serial arrangement of the internal combustion engine and electric motor(s) is provided. The advantage of this lies in the approximately 25% more efficient conversion of an amount of energy from a liquid fuel supplied to the internal combustion engine—compared to individual operation of the internal combustion engine using the Otto cycle.

Furthermore, according to the state of the art, an internal combustion engine according to Patent No. DE 879 183 B and an internal combustion engine according to the patent DE 601 16 942 T2 known as prior art. In each of these, a so-called 5-stroke combustion process is described, in which fuel can be converted into drive power with greater efficiency. However, these 5-stroke engines operated as traction motors have several disadvantages. When used as a traction motor, the swept volume is increased by the specific design from 2-litre to 4-litre motors (with around 20% more power). This leads to an unacceptable enlargement of the engine and is seen as the reason why this more efficient but disadvantageous machine design has not yet been able to gain acceptance technically. Furthermore, the dynamic operation of such a motor can only be represented inadequately. An idea to make the engine more powerful by turbocharging was in the patent DE 60116942 T2 released.

U.S. 5,881,559 A discloses a hybrid propulsion system for a vehicle with a four-cylinder engine, a generator, a battery and an electric motor. The four-cylinder engine drives the generator, which supplies electricity to the battery. The electric motor uses the battery power to drive one wheel of the vehicle.

invention

The object of the invention is to provide a drive unit for a motor vehicle which, while being practical, has a particularly high overall efficiency. It is also an object of the invention to provide a motor vehicle that will meet future environmental protection and fuel consumption requirements in a cost-effective manner.

According to the invention, the stated object is achieved by a drive unit according to claim 1 . A drive unit according to the invention for a motor vehicle comprises an internal combustion engine with at least two combustion chambers, in particular combustion cylinders, in which a fuel-air mixture (starting mixture) is reacted chemically exothermically at a time interval (ignition angle) in such a way that an exhaust gas mixture with compared to the starting mixture increased latent heat and increased pressure, with the exhaust gas mixture exerting a compressive force on pistons that are movably mounted in the combustion chambers in such a way that an output shaft (crankshaft) is set in rotation with the help of the pistons, with the combustion chambers being provided with another working space in the form of an expansion cylinder is assigned, in which the exhaust gas mixture expelled from the combustion chambers--with the release of mechanical power to the output shaft (crankshaft)--is relaxed and subsequently transferred to an exhaust gas outlet, with a first electromechanical energy converter being mechanically connected to the output shaft is coupled to the internal combustion engine and exchanges electrical energy with an electrical energy storage unit (accumulator, "battery"), and wherein a further electromechanical energy converter is mechanically coupled to at least one wheel shaft of the motor vehicle and also exchanges electrical energy with the electrical energy storage unit. In this case, the further electromechanical energy converter is provided for propelling the motor vehicle and for recovering braking energy. The first electromechanical energy converter, on the other hand, is preferably used on the one hand for an energy exchange between the crankshaft and the battery and on the other hand to adjust the load on the crankshaft and as a starter machine. The internal combustion engine is preferably operated with spark ignition using an Otto process in order to be able to control the operating behavior of the internal combustion engine particularly precisely. In principle, different types of combustion processes can be carried out in the combustion chambers, in particular constant-volume or constant-pressure processes in two-stroke or four-stroke mode. Especially in a two-stroke mode, a noticeable post-combustion of the exhaust gas mixture expelled from the combustion chambers can be realized in the expansion cylinder will. In a further embodiment of the invention, the combustion chambers of the internal combustion engine each have a compression ratio of less than 9:1, in particular less than 8:1.

In an embodiment of the invention, the internal combustion engine is operated in a predominant operating state in an approximately stationary manner in a speed range between 1000 rpm and 5000 rpm, or it is shut down. A fluctuation range of +/-250 rpm around a preferred value of 2000 rpm, for example, can be provided. In a particularly preferred manner, the operating state of the internal combustion engine is largely stationary in that range of the torque/speed level in which the lowest specific fuel consumption of the internal combustion engine is located. In addition, in a further preferred manner, the range of the highest efficiency of the first electromechanical energy converter is selected in precisely the same torque/speed range.

In a further embodiment of the invention, the internal combustion engine has at least two combustion chambers operated according to a four-stroke process and an expansion cylinder acting on the same output shaft, in which the exhaust gas mixture pushed out of the combustion chambers is expanded, the first electromechanical energy converter being mechanically coupled to the output shaft of the internal combustion engine and is mainly operated as a generator for charging a storage unit for electrical energy, with the additional electromechanical energy converter being provided as a drive and braking unit for at least one wheel shaft of the motor vehicle, with the internal combustion engine operating at a speed that fluctuates by less than 500 rpm (quasi stationary), in particular in a speed range between 1000 rpm and 5000 rpm is operated or stopped. Furthermore, the first electromechanical energy converter is preferably used according to the invention for adjusting the load and/or the torque of the internal combustion engine and for starting the internal combustion engine.

In a further embodiment of the invention, the internal combustion engine is assigned an exhaust gas turbocharger, in which the exhaust gas mixture discharged from the expansion cylinder is expanded further in an exhaust gas turbocharger, the air to be supplied to the combustion chambers being precompressed with the aid of the exhaust gas turbocharger. In this way, the overall efficiency of the drive can be further increased and exhaust gas energy can be utilized as far as possible. In front of and/or behind the exhaust gas turbocharger, at least one exhaust gas recirculation device is preferably provided for at least part of the exhaust gas that is expanded in the exhaust gas turbocharger.

In a further embodiment of the invention, the internal combustion engine has two four-stroke cylinders working at a uniform ignition interval of 360° and an additional, larger expansion cylinder for subsequent expansion of the exhaust gas mixture of the four-stroke cylinders, with the expansion cylinder expanding the combustion gases taken up alternately from the two four-stroke cylinders in a quasi two-stroke process, with the gases are transferred from the four-stroke cylinders through openings in a cylindrical wall of the expansion cylinder, in particular with a flow direction oriented approximately perpendicularly to the cylinder axis. According to the invention, the four-stroke cylinders preferably have the same lifting height and the same displacement. In contrast to this, the expansion cylinder preferably has a swept volume increased by at least 25%, which is set by appropriately selecting the cylinder diameter and stroke height, with the stroke height of the expansion cylinder being increased compared to the stroke height of the four-stroke cylinder. More preferably, the three cylinders described are arranged in series in such a way that the central cylinder axes all come to lie in a common plane. More preferably, the expansion cylinder protrudes beyond the two four-stroke cylinders in the area of the cylinder head, i.e. the upper reversing position of the piston in the expansion cylinder has a greater distance to the axis of rotation of the crankshaft than the top positions of the pistons of the four-stroke cylinders. An overflow channel can thus be provided between the expansion cylinder and the adjacent four-stroke cylinder, which extends between an outlet opening on the essentially round end face of the four-stroke cylinder and a slot-shaped opening in the cylindrical wall of the expansion cylinder. Such an overflow channel can preferably have a flow deflection of 90° or less.

In a further embodiment of the invention, at least one wall of the expansion cylinder and/or one wall of the piston guided in the expansion cylinder has a layer made of a material which reduces heat losses and whose thermal conductivity λ is lower than 200 W/(m * K), in particular lower than 50 W /(m * K). An almost adiabatic expansion of the exhaust gas and/or post-combustion can thus be implemented in the expansion cylinder.

In a further embodiment of the invention, the internal combustion engine is assigned thermally effective insulation such that an internal temperature of the internal combustion engine of more than 100° C. under standard ambient conditions, in particular at an outside temperature of 20° C., drops by less than 3 K per minute. According to the invention, the internal combustion engine has an insulating Encapsulation, the components of which can have different thermal insulation properties, but the overall behavior causes the (stopped) internal combustion engine to cool by less than 3 K/min.

In a further embodiment of the invention, the exhaust lifting valve blocking the exhaust gas outlet of the expansion cylinder is made entirely or partially of a ceramic material. The outlet stroke valve of the expansion cylinder thus has a low heat storage capacity and makes a lasting contribution to the thermal insulation of the expansion cylinder.

In a further embodiment of the invention, the exhaust lift valve blocking the exhaust gas outlet of the expansion cylinder has a main axis which is aligned parallel to the main axis of the expansion cylinder, preferably arranged to coincide with it. On the one hand, this allows the flow conditions to be optimized when the exhaust gases are transferred to a connected exhaust line. On the other hand, a cover part of the expansion cylinder can be produced in a rotationally symmetrical manner in a manner that is favorable in terms of manufacturing technology.

In a further embodiment of the invention, the internal combustion engine has a first cylinder group with two four-stroke cylinders working with a uniform ignition interval and an additional expansion cylinder for subsequent expansion of the exhaust gas mixture of the four-stroke cylinders, with the expansion cylinder expanding the combustion gases taken up alternately from the two four-stroke cylinders, and with the internal combustion engine having at least one second cylinder group, which is designed essentially the same as the first cylinder group and is arranged in a V-shape, star shape or boxer shape at an angle greater than 0° to the first cylinder group, the first and the second cylinder group sharing a common output shaft (crankshaft ) drive. In this case, the crankshaft is preferably coupled to one or two electromechanical energy converters, which each deliver electrical energy to a battery connected to the electromechanical energy converter. Internal combustion engines designed in this way are also used in particular in boat and aircraft engines.

In the case of the invention, second-order inertia forces are compensated for by balancing masses moved at twice the crankshaft speed. In particular, the different leverage and mass ratios in the combustion cylinders on the one hand and the expansion cylinder on the other hand can be advantageously compensated according to the invention by means of a balancer shaft.

The object is also achieved by a motor vehicle with the features of claim 12. A motor vehicle according to the invention has a drive unit including an internal combustion engine with at least two combustion chambers, in particular combustion cylinders, in which a fuel-air mixture is produced at a time interval (ignition angle). (Starting mixture) is reacted chemically exothermally in such a way that an exhaust gas mixture with increased latent heat compared to the starting mixture and with increased pressure is generated. Furthermore, the exhaust gas mixture exerts a compressive force on the pistons that are movably mounted in the combustion chambers in such a way that the pistons are used to set an output shaft (crankshaft) in rotation, with the combustion chambers being assigned another working chamber in the form of an expansion cylinder, in which from the combustion chambers discharged exhaust gas mixture is expanded with the release of mechanical power to the output shaft (crankshaft) and subsequently transferred to an exhaust gas outlet. Furthermore, the drive unit has a first electromechanical energy converter, which is mechanically coupled to the output shaft of the internal combustion engine and exchanges electrical energy with a storage unit for electrical energy, and a further electromechanical energy converter, which is mechanically coupled to at least one wheel shaft of the motor vehicle and also electrical energy exchanges with the storage unit for electrical energy. According to the invention, this results in a motor vehicle that can be driven with high efficiency over a wide operating range in that the internal combustion engine is operated if required in a range of low specific consumption at a moderate speed. According to the invention, the requirement is essentially determined on the basis of the state of charge of the storage unit for electrical energy (accumulator, “battery”). Load peaks can be managed exclusively by an electric motor, as can starting processes, without making changes to the operating state of the internal combustion engine or even switching it on. The battery serves as a balancing reservoir for energy between the continuous performance level of the stationary internal combustion engine, which can be operated particularly efficiently, and the briefly discontinuous performance requirements when operating modern motor vehicles.

In an embodiment of the invention, the drive unit, in particular the internal combustion engine, is assigned thermally effective insulation in such a way that an internal temperature of the internal combustion engine of more than 100° C. under standard ambient conditions (in particular 20° C. air temperature) and with an oncoming airstream with a flow speed of 80 km /h also at switched off or shut down the internal combustion engine by less than 3 K per minute.

In a further embodiment of the invention, the internal combustion engine has a first cylinder group with two four-stroke cylinders and an additional expansion cylinder for subsequent expansion of the exhaust gas mixture of the four-stroke cylinders, the expansion cylinder expanding combustion gases taken alternately from the two four-stroke cylinders, and the cylinder group having a common exhaust gas outlet and has a subsequent common, thermally insulated exhaust gas pipe, the radial thermal conductivity of which is designed to be lower than 50 W/(m * K).

In a further embodiment of the invention, the internal combustion engine is assigned a catalytic converter in the area of an exhaust pipe, with exhaust gas being removed from the exhaust pipe in the direction of flow downstream of the catalytic converter and being routed via targeted exhaust gas recirculation to a heat exchanger, via which heat is transferred from the exhaust gas to the cooling water, wherein the cooled exhaust gas is then fed either to the suction side of the internal combustion engine or again to the exhaust pipe. In a particularly advantageous manner, exhaust gas from the internal combustion engine is fed to an exhaust gas turbocharger after exiting the expansion cylinder. Downstream of the exhaust gas turbocharger, an exhaust gas purification catalyst and a pipe branching element are installed in the exhaust line, with at least part of the exhaust gas being able to be fed to said heat exchanger and possibly then to the internal combustion engine by means of the pipe branching element.

In a further embodiment of the invention, the drive unit is designed as a serial hybrid system in such a way that the design power is less than or equal to the associated power value according to the driving resistance line of the motor vehicle on the level, which is at a defined reference speed, in particular at 125 km/h, at 145 km/h. h or 160 km/h on the flat. In particular, a continuous cruising speed on the level is assumed as the reference speed, which can also be selected differently from country to country and/or for standard or sports cars. When driving at a constant reference speed on level ground, the vehicle preferably has a power requirement that is selected as the design power of the internal combustion engine and as the design power of the entire hybrid system. Higher power requirements than the design power - for example when driving uphill and/or higher vehicle speed - are covered according to the invention essentially by briefly drawing power from the electrochemical energy store (accumulator, battery).

• 1 in einer Prinzipskizze ein erstes erfindungsgemäßes Kraftfahrzeug mit einer Brennkraftmaschine („5-Takt-Motor“) in einer seriellen Hybridanordnung,
• 2 in einer Prinzipskizze ein zweites erfindungsgemäßes Kraftfahrzeug mit einer Brennkraftmaschine („5-Takt-Motor“) in einer seriellen Hybridanordnung,
• 3 in einem Längsschnitt eine dritte erfindungsgemäße Brennkraftmaschine mit drei Zylindern,
• 3a einen Zylinderkopf für eine vierte erfindungsgemäße Brennkraftmaschine in einem Längsschnitt, einem Querschnitt sowie einer Ansicht von unten,
• 4 in einem Längsschnitt einen Ausschnitt der Brennkraftmaschine nach 3,
• 5 in einem Querschnitt die Brennkraftmaschine nach 3,
• 5a in einer ausschnittsweisen Prinzipdarstellung eine modifizierte erfindungsgemäße Antriebseinheit,
• 5b in einem Temperatur-Zeit-Diagramm einen Temperaturverlauf einer erfindungsgemäßen Brennkraftmaschine bei zunächst stillgesetzter Brennkraftmaschine,
• 5c in einem Prinzip-Schaubild den Ladezustand der Batterie [in Prozent vom Soll-Ladezustand) in einem erfindungsgemäßen Kraftfahrzeug bei Durchfahren eines NEFZ-Fahrzyklus sowie
• 6 in einem Prinzip-Diagramm eine Fahrwiderstandskurve eines erfindungsgemäßen Kraftfahrzeugs.

Further features, advantages and variants emerge from the claims and the following description, in which advantageous exemplary embodiments of the invention are described with reference to the drawings. show this

• 1 in a schematic diagram, a first motor vehicle according to the invention with an internal combustion engine (“5-stroke engine”) in a serial hybrid arrangement,
• 2 in a schematic diagram, a second motor vehicle according to the invention with an internal combustion engine (“5-stroke engine”) in a serial hybrid arrangement,
• 3 in a longitudinal section, a third internal combustion engine according to the invention with three cylinders,
• 3a a cylinder head for a fourth internal combustion engine according to the invention in a longitudinal section, a cross section and a view from below,
• 4 a section of the internal combustion engine in a longitudinal section 3 ,
• 5 the internal combustion engine in a cross section 3 ,
• 5a in a sectional schematic representation of a modified drive unit according to the invention,
• 5b in a temperature-time diagram, a temperature profile of an internal combustion engine according to the invention when the internal combustion engine is initially stopped,
• 5c in a principle diagram the state of charge of the battery (as a percentage of the target state of charge) in a motor vehicle according to the invention when driving through an NEDC driving cycle and
• 6 in a principle diagram, a driving resistance curve of a motor vehicle according to the invention.

Preferred Embodiments

According to the present invention, a motor vehicle according to the invention in the form of a passenger car 1 is equipped with a drive unit 2 according to the invention, which is described below with reference to FIG 1 until 5 is explained in more detail. The motor vehicle can be designed as a utility vehicle for transporting goods, as well as a motorcycle, omnibus, construction vehicle or the like. Alternatively, the motor vehicle can also be operated on rails. In any case, it points a driven wheel shaft 4 rotated by the drive unit and at least one driven wheel 5 .

The drive unit 2 essentially comprises an internal combustion engine 2.1, referred to elsewhere as a “5-stroke engine”. The internal combustion engine 2.1 in turn has at least two combustion chambers V, in particular combustion cylinders 2.2, in each of which a fuel-air mixture (initial mixture) is reacted chemically exothermally at a time interval in such a way that an exhaust gas mixture with an increased latent Heat and increased pressure is generated, with the exhaust gas mixture exerting a compressive force on the pistons Z, which are movably mounted in the combustion chambers V, in such a way that with the help of the pistons Z, an output shaft 2.4 (“crankshaft”) is set in rotation, with the combustion chambers V a further working chamber in the form of an expansion cylinder 2.3 is assigned, in which the exhaust gas mixture pushed out of the combustion chambers is expanded with the release of mechanical power to the output shaft 2.4 and subsequently transferred into an exhaust gas outlet 20. The internal combustion engine 2.1 receives liquid or gaseous fuel for operation, in the form of a preferably organic substance, e.g. B. petrol or diesel fuel or petrol, alcohol, biogas or methane or hydrogen gas or the like from a fuel tank 3 carried in the motor vehicle 1.

The internal combustion engine 2.1 according to the invention has in particular at least two reciprocating piston cylinders 2.2 (two-stroke or four-stroke cylinders) working at an ignition interval of 360° with combustion chambers V, in which the fuel is burned exothermically with ambient air using an Otto process, preferably with external ignition .

in den Brennräumen ist jeweils kleiner als 9 : 1, insbesondere kleiner als 8 : 1 gewählt, wobei V_H = Hubvolumen, V_K = Kompressionsvolumen der Brennräume. The compression ratio $e=\frac{V_H+V_K}{V_K}$

in the combustion chambers is selected to be less than 9:1, in particular less than 8:1, where V _H =stroke volume, V _K =compression volume of the combustion chambers.

Furthermore, the internal combustion engine 2.1 has a further reciprocating piston cylinder 2.3 (expansion cylinder) for a subsequent further expansion of the combustion gases (fifth stroke). This expands combustion gases transferred from the two combustion cylinders 2.2 and pushes them via an exhaust gas outlet into a downstream exhaust pipe 6.1, 6.2. The further reciprocating piston cylinder 2.3 (expansion cylinder) preferably works in a type of two-stroke process, with the exhaust gas from the combustion cylinder 2.2 being expanded essentially adiabatically, with the release of mechanical work. Like the pistons of the other two cylinders 2.2, the piston of the expansion cylinder 2.3 prefers to deliver its power to a common output shaft 2.4 (crankshaft) (cf. in particular 3 ).

A first electromechanical energy converter G (“generator”) is coupled to the crankshaft 2.4 via a clutch and/or a gear. A specific embodiment of the first electromechanical energy converter G can U.S. 2009/0224628 A1 be taken, to which reference is made in full with regard to the structure (in particular the construction of the stator and the rotor using permanent magnets) and the operating conditions of the generator G. With the help of power electronics E, this generator G exchanges electrical energy with a storage unit B for electrical energy (“battery”, accumulator) via electrical connecting cables 2.5, 2.6. A process computer or a control unit C regulates both the operating state of the generator G and the operating state of the battery B and that of the internal combustion engine 2.1. During the operation of the motor vehicle 1, the first electromechanical energy converter G is mainly used as a generator in order to tap mechanical energy from the internal combustion engine 2.1 and transfer it to the battery B in the form of electrical energy. When the motor vehicle 1 is in operation, the generator G can also be used to start and accelerate the internal combustion engine 2.1 from a standstill. It is preferable to convert the internal combustion engine 2.1 with the aid of the first electromechanical energy converter G as quickly as possible from an idle state (standstill) to the optimal operating state, in that the internal combustion engine 2.1 is dragged by the generator G into an operating state at nominal speed. According to the invention, the rated speed should be in a range of the (mathematical-physical) torque-speed diagram of the internal combustion engine in which the internal combustion engine has a particularly low specific fuel consumption. The first electromechanical energy converter G is also provided to provide the then working internal combustion engine 2.1 with a rated load that is also in a range of the torque/speed diagram of the internal combustion engine in which the internal combustion engine has a particularly low specific fuel consumption. According to the invention, the generator G should also have the best possible efficiency at nominal speed and nominal load, in particular not deviating by more than 15% from its maximum efficiency.

According to 1 is the internal combustion engine so assigned an electromechanical energy converter in the form of a generator G, with or is mechanically coupled to an output shaft of the internal combustion engine 2.1 without a gear or clutch and can be driven by the internal combustion engine 2.1. The generator G can, as in 3 shown in detail, be placed directly on a crankshaft of the internal combustion engine on the rotor side. The generator G is designed in such a way that it also has the highest possible efficiency at the best point (chosen for the internal combustion engine 2.1), the currents to be delivered and the voltage(s) of the generator G in turn being coordinated with the current storage unit B. Because the subsystem described so far (internal combustion engine, generator, electronics, battery) essentially works under the same conditions, all design parameters can be optimized for these conditions.

According to the invention, the internal combustion engine is operated in a preferred exemplary embodiment in a quasi-stationary manner at a nominal speed of 2000 rpm with an almost constant torque of 150 Nm against the load of the first electromechanical energy converter G. A preferred fluctuation range of the rotational speed during a driving cycle of the motor vehicle 1 is 500 rpm around the nominal rotational speed (ie approx. +/-250 rpm). In addition, the nominal speed itself can also be adjusted within such a range (perhaps permanently)--depending, for example, on permanently changed performance requirements for the internal combustion engine, on (varying) fuel properties or ambient conditions. A demand-dependent fluctuation of the torque of +/- 30 Nm around the nominal value or a permanent adjustment of the load conditions on the internal combustion engine 2.1 within such a range is possible according to the invention (especially if an adjustment corresponds to a changing (overall) maximum efficiency of the drive unit follows).

In another exemplary embodiment, the internal combustion engine is operated in a quasi-stationary manner at a rated speed of approximately 3500 rpm and a rated torque of approximately 100 Nm. The performance parameters of the associated components, the internal combustion engine, generator, power electronics and battery, are matched to this operating state.

The internal combustion engine is preferably operated in particular under nominal conditions until the battery B has reached a proportion of 75% (or possibly optionally also of 85% or 100%) of the maximum storage capacity provided for operation (target state of charge SOC) due to the supply of electrical energy is. When such a state of charge of the battery is reached, the computer unit C should shut down the internal combustion engine 2.1 and only if necessary, e.g. if the state of charge falls below 50% below the target state of charge SOC (or when the state of charge is 45% or 60% of the target -State of charge) or when the motor vehicle has performance requirements above the performance level of the battery B can be restarted. In this case, 100% of the target state of charge preferably corresponds to between 50% and 75% of the physically possible maximum state of charge of the battery. The level of the target state of charge is preferably selected as a function of the average idle times of the vehicle.

To complete the serial hybrid drive, the drive unit 2 of the motor vehicle 1 (as can be seen from the 1 and 2 can be seen) has a further electromechanical energy converter in the form of a (drive) motor-generator unit M/G. The (drive motor) generator unit M/G is connected, for example, via a differential D and/or a gear (not shown) to a drive shaft (wheel shaft 4), which directly drives the wheels of the motor vehicle.

The additional electromechanical energy converter M/G (motor generator unit) also exchanges electrical energy with the storage unit B for electrical energy via connecting cables 2.6, 2.7 and electronics E. The process computer or the control unit C regulates both the operating state of the motor-generator unit M/G and the operating state of the battery B. The operating parameters of the motor-generator unit M/G are matched to the operating behavior of the motor vehicle since the motor-generator unit M/G draws its energy from the battery and is largely decoupled from the internal combustion engine and generator components in particular.

In a (not shown) modified embodiment, separate drive electric motors can be provided for the axles individually assigned to the wheels, which in turn could draw their power from a central power storage unit. According to the invention, one or more drive motor-generator units M/G serve as traction motors, which transmit the torque required for propulsion of the motor vehicle to the wheels.

In a further (not shown) modified exemplary embodiment, both the motor-generator unit M/G and the internal combustion engine can be coupled or can be coupled to the wheel shaft 4 via a differential and/or a (planetary) gear and/or a clutch, see above that there is an alternative configuration of the drives means 2 results. In particular when the motor vehicle is operated over long distances at a largely constant and high speed of the motor vehicle, it can also make sense to mechanically transfer a portion of the load from the internal combustion engine to the wheel shaft 4 . This load component can be lower than the nominal load of the internal combustion engine 2.1 if the battery B is charged at the same time.

In a modified exemplary embodiment, an internal combustion engine 2.1 for a drive unit 2 according to the invention has a plurality of cylinder groups each consisting of two high-pressure cylinders and one (much) larger expansion cylinder (low-pressure cylinder) each. Said groups of cylinders can be arranged in relation to one another in rows, in a V-shape, in a box shape or in a star shape (not shown in detail).

In further modified exemplary embodiments, inertia forces of the second order are compensated, if necessary, by balancing masses moved at twice the crankshaft speed. For this purpose, a balancer shaft coupled to the crankshaft via a fixed gearing is provided with balancing weights. In this case, provision can be made for the masses of the pistons of the combustion cylinders to be summed up on the one hand and of the piston of the expansion cylinder on the other hand to be different; in particular, the individual masses could be made approximately the same (especially the same low).

Another variant of the drive unit 2 according to the invention 2 includes another variant of an internal combustion engine according to the invention, which from the DE 60116942 T2 can be extracted in detail. the DE 60116942 T2 is made a part of this application in its entirety with regard to a possible structure and basic operating methods of the internal combustion engine 2.1. In particular, in one embodiment 2 one in the DE 60116942 T2 exhaust gas turbocharger unit 7 (exhaust gas turbocharger, ATL) explained in detail, which is switched on in the exhaust gas lines 6.1, 6.2. The exhaust gas mixture discharged from the internal combustion engine is expanded by means of the exhaust gas turbocharger unit 7 and fresh air is precompressed by means of the recovered energy for supply to the internal combustion engine. For this purpose, the exhaust gas expelled from the expansion cylinder 2.3 is fed to an expansion turbine of the exhaust gas turbocharger 7 via the exhaust gas line 6.1. The mechanical energy obtained is transferred from the expansion turbine to a compressor wheel of the exhaust gas turbocharger 7, with which the ambient air to be supplied to the internal combustion engine 2.1 can be precompressed. Downstream of the turbocharger is an exhaust gas cleaning catalytic converter CC.

According to the invention, the internal combustion engine 2.1 (“5-stroke engine”) is operated particularly efficiently in an essentially stationary manner at an almost constant speed (or in a small speed range of +/- 250 rpm around the nominal speed) and integrated into a serial hybrid system, such as results from the further description. The constant speed and the power of the internal combustion engine to be delivered with it are preferably selected in such a way that a point of the best possible efficiency or maximum efficiency of the internal combustion engine (best point) is approximated as well as possible. if the internal combustion engine is no longer required, it can be shut down and restarted at the appropriate time. According to the invention, the best point lies in a speed range from 1000 rpm to approximately 5000 rpm, in particular between 1000 rpm to approximately 3500 rpm.

In principle, a serial hybrid system can be designed for a traction drive with an average drive power of significantly more than 30 kW. According to the invention, such an overall system is designed in such a way that the power that can be continuously delivered by means of the internal combustion engine 2.1 and generator G is less than or equal to the required drive power at the legal or otherwise previously specified maximum speed and/or at a previously specified continuous cruising speed. According to the invention, rated power values of 28 kW, 40 kW or 60 kW are selected for continuous cruising speeds of a medium-sized car of 125 km/h, 145 km/h or 160 km/h. Correspondingly deviating values are provided for smaller or larger vehicles.

Out of 6 results in a preferred design of a drive concept for a motor vehicle 1 according to the invention in accordance with the previous exemplary embodiments. The electrical power provided by the internal combustion engine 2.1 together with the generator G should be just high enough for the internal combustion engine 2.1 and the directly coupled generator G to be able to produce a predetermined setpoint speed v _Dmax at rated output over the long term. According to the invention, such a maximum continuous speed v _Dmax is set at approximately 120 km/h. Based on a driving resistance curve FK of a mid-range vehicle 6 For this purpose, a rated power P _N to be installed by generator G and internal combustion engine 2.1 can be determined: At a constant vehicle speed of 120 km/h, this is approximately 28 kW, which results from the Cartesian coordinates of point F1 on the driving resistance line FK.

Performance requirements that go beyond this (higher gradients, higher speeds, higher payloads) are to be met in the short term by a time-limited energy withdrawal from a “buffer battery” B (or from the accumulator). Such a "buffer battery" can store about 6 kWh of energy according to the invention, with the 6 a driving speed v _x of the motor vehicle of 185 km/h on level ground over a period of 5 minutes would be possible (point F2). With the same amount of energy, however, a driving speed v _y of 140 km/h could be achieved for a period of about 25 minutes (point F3) until battery B was largely discharged. After battery B was discharged, the vehicle should move below point F1 according to the invention to allow battery B to be gradually recharged.

With the configuration described, displacements between 0.6 l and 1.6 l on the 5-stroke engine are required for today's standard passenger cars. By using the electric motor operating condition, all load conditions in city traffic are electrically covered in real driving operation. From speeds of approx. 60 km/h, the internal combustion engine 2.1 is temporarily switched on and the battery B is temporarily charged - while at the same time energy is being drawn by the (drive) motor-generator unit M/G.

In the combination of the various drive components (“5-stroke engine”, generator, battery and electric drive motor), the principle advantages of the components should be fully utilized and the corresponding disadvantages of the individual components should be avoided. This is achieved in particular by the fact that the "internal combustion engine - generator - battery" line is in principle decoupled from the "drive electric motor - battery" line and the internal combustion engine and generator can then be operated close to a best efficiency point.

Other design details of other internal combustion engines according to the invention can in particular 3 , 3a , 4 and 5 be removed. Reference symbols of the same or similar components have been chosen to be the same as in the exemplary embodiments described above. Incidentally, the in the 3 , 3a , 4 and 5 illustrated internal combustion engines 2.1 in motor vehicles according to 1 and 2 (including variants) can also be used in combination with one another if necessary. Likewise they are in an assembly after 5a usable.

Further details of another internal combustion engine 2.1 according to the invention are shown in FIG 3 (a simplified longitudinal section through a 5-stroke engine according to the invention) and from 4 (an enlarged detail of the same engine). Combustion cylinders 2.2 (four-stroke cylinders) are preferably operated in a four-stroke process, which is why an intake valve 12 and an exhaust valve 13 in a cylinder head K are assigned to them. During operation, the valves are caused (in a manner known per se) by a camshaft 14 to perform a translational movement against the forces of a closing spring 19 in each case, with the camshaft 14 being coupled to the crankshaft 2.4 via a belt or chain transmission 15 and being mounted on the cylinder head K . Spark plugs are not shown, but are preferably used to carry out a four-stroke Otto combustion process.

The combustion cylinders 2.2 are arranged with the expansion cylinder 2.3 essentially in one and the same plane, with the respective pistons of the cylinders 2.2, 2.3 acting on the common crankshaft 2.4 via connecting rods that are preferably of the same length. In the exemplary embodiment shown, a piston mass of the piston 11 in the expansion cylinder 2.3 is preferably selected to be approximately twice as large as the mass of a piston in a combustion chamber of a combustion cylinder 2.2. Furthermore, the diameter of the expansion cylinder 2.3 is about 25% to 45%, in particular about 40% larger than the diameter of a combustion chamber V. The displacement of the expansion cylinder 2.3 is also advantageously about 100% larger than the displacement of a combustion cylinder .

In particular, is off 3 It can be seen that the combustion cylinders 2.2 are arranged with a small lateral distance and in a row with the expansion cylinder 2.3. In addition, the expansion cylinder 2.3 is offset upwards in relation to the two combustion cylinders 2.2 in the direction of the cylinder head K, so that an overflow channel 16 can be configured in the cylinder head K between the combustion cylinders 2.2 on the one hand and the expansion cylinder 2.3 on the other. An overflow channel 16 has a substantially circular opening L (outlet opening of the combustion cylinder) at the upper front end of the combustion chamber of a combustion cylinder 2.2, which can be closed by the outlet valve 13 of the associated combustion cylinder 2.2. Over its length, the overflow channel 16 initially has a circular cross section and finally an essentially rectangular cross section, with which it opens into the expansion cylinder 2.3 at the upper end. The overflow channel 16 preferably has a length of less than 5 cm.

Advantageously, the overflow channels 16 not only have a short length but also a small curvature with a correspondingly reduced deflection angle (with a change in direction of, for example, 70° to 90°) - the harmful dead space in the overflow channels 16 is correspondingly small.

According to the invention, the gases are transferred from the combustion cylinders 2.2 through slot-shaped openings 17 in the cylindrical wall of the expansion cylinder 2.3 with a direction of flow approximately perpendicular to the cylinder axis of the expansion cylinder 2.3.

Furthermore, according to the invention, the compression ratio ε of the combustion cylinders 2.2 is reduced by 10% to 20% compared to the usual values (ε=9.5), i.e. if there is no subsequent further expansion (i.e. according to the invention ε=8.55 to 7.6) and in additional expansion cylinder increased. In previous engines without additional expansion, the compression ratio (equal to the expansion ratio) was chosen to be as high as possible. This results in the highest demands on the anti-knock properties of the fuel and the highest pressures and forces on many parts. In contrast, a clear advantage is achieved according to the invention in that the combustion cylinders 2.2 experience lower structural loads.

The internal combustion engine is shown in Figure 4 3 for a drive unit according to the invention shown in detail in a partial longitudinal section through the internal combustion engine 2.1 (or a section through an individual cylinder group). The overflow channels 16 between the 4-stroke cylinders 2.2 (combustion chamber cylinders; in 4 right and left) and the central, larger expansion cylinder 2.3. The expansion cylinder preferably has an increased length compared to the combustion chamber cylinders 2.2 and/or an increased diameter compared to the combustion chamber cylinders 2.2.

According to the invention, it is now provided that the walls of the additional expansion cylinder 2.3 have a heat loss-reducing coating T1, T2, T3, T4 made of a suitable material. An annular area close to the cylinder head K (or adjacent to the cylinder head K) can have a 0.1 mm to 2 mm thick coating and/or an annular insert T1 made of a material with the lowest possible thermal conductivity. According to the invention, for example, coatings or inserts made of stainless steel, in particular nickel-containing steel or ceramics, more preferably aluminum oxide, (hard) anodized aluminum, nickel, titanium or the like are provided. On the remaining cylinder wall of the expansion cylinder 2.3, a coating up to 100 μm thick or surface treatment T2 made of a similar material can optionally be carried out. A 0.1 mm to 2 mm thick coating and/or a disc-shaped insert T3 made of one of the above-mentioned materials with the lowest possible thermal conductivity can also be provided on the underside of the cylinder head K in the area of the expansion cylinder 2.3. Finally, a 0.1 mm to 2 mm thick coating and/or a dome-shaped attachment T4 made of a material with the lowest possible thermal conductivity is particularly preferably also provided on an upper side of the piston 11 of the expansion cylinder. In a modified embodiment, the piston of the expansion cylinder is made of a ceramic material for more than 50% of its volume.

In the combustion chamber cylinders 2.2, the walls must be kept at a relatively low temperature by liquid cooling so that the amount of charge does not decrease due to heating on the walls and ignition due to compression on a hot wall must not occur. However, these requirements do not apply to the expansion cylinder 2.3, so that mechanical work can be gained at a constantly high temperature (especially in adiabatic expansion) and less cooling heat has to be dissipated.

In modified exemplary embodiments, cylinder liners made of ceramic materials, in particular stainless steel containing nickel, titanium or the like, are provided for the expansion cylinder 2.3.

According to the invention, an outlet valve 18 is assigned to the expansion cylinder in the middle, i.e. preferably with an identical (symmetry) axis, via the exhaust gas that can be transferred from the additional expansion cylinder into the exhaust system. The outlet (lift) valve 18 blocking the exhaust gas outlet H, 20 of the expansion cylinder (2.3) has a main axis which is aligned parallel to the main axis AH of the expansion cylinder, preferably arranged to coincide with it.

Said outlet (lift) valve 18 can be made entirely or partially from a ceramic material and/or from a light metal such as titanium and/or can be provided with a ceramic coating. The low mass has a positive effect, e.g. on noise and lower mass forces. Lower heat dissipation coupled with increased valve temperature can result in a reduction in expansion cylinder heat losses.

According to 3a another exemplary embodiment of an internal combustion engine according to the invention is shown with regard to its cylinder head K. while showing 3a starting from the top right: longitudinal section through the cylinder head K of an internal combustion engine similar to that in FIGS 3 and 4 internal combustion engine shown; a cross section through the cylinder head in the area of the expansion cylinder along line II; Bottom view of the cylinder head along plane II-II.

In 3a a view of a slot-shaped outlet opening 17 of the overflow channel in the expansion cylinder is shown in the upper right figure. The roughly crescent-shaped three-dimensional design of the overflow channels can also be seen in the top left figure in 3a removable. In addition, the inlet openings I and the outlet openings A of the combustion cylinders can be seen just as clearly as the (single) outlet opening H of the expansion cylinder, the entire exhaust gas of the internal combustion engine passing through the latter into an exhaust tract that is not shown in detail.

In 5 a section through an intake valve 12 of an internal combustion engine 2.1 for a further, modified drive unit 2 according to the invention is shown. An essential aspect here is that the internal combustion engine after 5 a substantially complete encapsulation 50 which serves as thermal and acoustic insulation. Such an encapsulation 50 according to the invention is intended to be penetrated in particular by an intake pipe 20A, an exhaust pipe and possibly one or more electricity lines (cables) and a fuel line. Otherwise, such an optimized insulation could be completely closed. According to the invention, the insulation can be designed using a plastic capsule 51 with an enclosed air layer, using a foam casing 52 and/or some other housing with low heat transfer coefficients. The insulation is preferably continued in the area of an exhaust gas pipe 6.2, so that the exhaust gas supplied to an exhaust gas cleaning catalytic converter CC arrives at the catalytic converter as warm as possible. In a preferred embodiment, the encapsulation includes several different insulation elements 50, 51, 52, which extend over at least 80% of the outer surface of the internal combustion engine, so that it is effectively protected against heat loss due to heat radiation and ambient air flow.

In an embodiment of the invention, the drive unit, in particular the internal combustion engine 5 a thermally effective insulation assigned in such a way that an internal temperature of the internal combustion engine of more than 100°C under standard ambient conditions (in particular 20°C air temperature) and with an airstream flow at a flow rate of 80 km/h drops by less than 3 K per minute. For this purpose, an estimate in the 5b and 5c shown, from which an exemplary course of the engine core temperature MT results when the internal combustion engine is switched off and a motor vehicle according to the invention runs through an NEDC driving cycle. According to the invention, the engine core temperature MT is preferably measured at the cylinder head K or at the crankcase.

In 5c the battery state of charge SOC [in percent of the maximum] and the vehicle speed v [in km/h] over the test cycle time [in seconds] are shown in a solid line (in addition to the engine core temperature MT). A motor vehicle with the following data is assumed to determine the data: mass m = 1300 kg, drag coefficient cw = 0.32, frontal area A = 2.17 m ² , fR = 0.01, Ä = 1.11; full 6.5, f_rec =0.9.

In 5a a system and a method for exhaust gas energy recovery according to the invention are illustrated, which can be combined with the previously described exemplary embodiments. Correspondingly, identical reference symbols are assigned to elements that are the same or have the same effect.

The system for exhaust gas energy recovery includes similar to the motor vehicle 1 after 2 an inventive multi-cylinder internal combustion engine 2.1 according to one of the exemplary embodiments described above, an exhaust gas turbocharger 7 and an exhaust gas catalytic converter CC. In a first stage, energy is removed from the exhaust gas via an expansion cylinder 2.3 of the internal combustion engine 2.1 (5-stroke engine, see above) by the exhaust gas being post-expanded in the expansion cylinder 2.3. The heat and pressure of the exhaust gas are converted into mechanical work, as it were in a fifth working stroke, and brought directly to the crankshaft 2.4 of the internal combustion engine 2.1. The exhaust gas expanded in this way is fed to the exhaust gas turbocharger 7 via an exhaust pipe 6.1. In a second stage, further energy is extracted from the exhaust gas by means of the exhaust gas turbocharger 7 before the exhaust gas enters an exhaust gas aftertreatment system (catalyst CC). The exhaust gas turbocharger compresses combustion air, which is supplied to the combustion cylinders 2.2 via an intake pipe 20A, and thus transfers energy taken from the exhaust gas to the combustion air to be compressed.

In a third stage, for example, in a cold start process, residual exhaust gas heat (after the catalytic converter CC) can be transferred via an exhaust gas/water heat exchanger W to a cooling water circuit 2.8 of the internal combustion engine 2.1. For the latter, a control valve 6.3 is arranged in an exhaust gas branch pipe 6.4. How out 5a it becomes clear that the exhaust gas cooled in this way should be fed back into an intake pipe 20B after an air filter F of the internal combustion engine in a cold start process, resulting in a quasi fourth stage of the Energy recovery or energy retention results.

Further features and combinations of features result from combinations of the exemplary embodiments described above and from the dependent claims in any combination.

Claims (15)

Comprising a drive unit, in particular for a motor vehicle - An internal combustion engine (2.1) with at least two combustion chambers (V) in combustion cylinders (2.2), in each of which a fuel-air mixture (starting mixture) is reacted chemically exothermally at a time interval in such a way that an exhaust gas mixture with an increased latent Heat and increased pressure is generated, with the exhaust gas mixture exerting a compressive force on the pistons (Z) movably mounted in the combustion chambers (V) in such a way that an output shaft (2.4) (crankshaft) is set in rotation with the help of the pistons (Z), wherein a first electromechanical energy converter (G) is mechanically coupled to the output shaft (2.4) of the internal combustion engine (2.1) and exchanges electrical energy with a storage unit for electrical energy (B), and wherein a further electromechanical energy converter (M/G) mechanically communicates with at least a wheel shaft (4) of the motor vehicle (1) is coupled and also electrical energy with the storage unit (B) for ele exchanges ktric energy, where - the internal combustion engine (2.1) has at least two combustion chambers (V) operated according to a four-stroke process and an expansion cylinder (2.3) acting on the same output shaft, in which the exhaust gas mixture pushed out of the combustion chambers (V) is post-expanded, wherein - the combustion chambers (V) are assigned a further working chamber in the form of the expansion cylinder (2.3), in which the exhaust gas mixture pushed out of the combustion chambers (V) is expanded while delivering mechanical power to the output shaft (2.4) and then fed into an exhaust gas outlet (20 , 6.1) is converted, and where - Second-order inertia forces are compensated for by a balancer shaft with balancer masses which is coupled to the output shaft (2.4) via a fixed gear and which is moved at twice the crankshaft speed. Drive unit for a motor vehicle claim 1 , wherein the internal combustion engine (2.1) in a predominant operating state is operated approximately stationary in a speed range between 1000 rpm and 5000 rpm or is shut down. Drive unit for a motor vehicle according to one of Claims 1 until 2 , wherein the first electromechanical energy converter (G) is mechanically coupled to the output shaft (2.4) of the internal combustion engine and is mainly operated as a generator for charging the storage unit (B) for electrical energy, the further electromechanical energy converter (M/G) as a drive and braking unit for the at least one wheel shaft (4) of the motor vehicle (1), the internal combustion engine (2.1) operating at a speed that fluctuates by less than 500 rpm (quasi stationary), in particular in a speed range between 1000 rpm and 5000 rpm is operated or stopped. Drive unit for a motor vehicle according to one of Claims 1 until 3 , wherein - the internal combustion engine (2.1) is assigned an exhaust gas turbocharger (7) which further expands the exhaust gas mixture discharged from the expansion cylinder (2.3) in an exhaust gas turbocharger (7), wherein - air to be supplied to the combustion chambers (V) is precompressed with the aid of the exhaust gas turbocharger . Drive unit for a motor vehicle according to one of Claims 1 until 4 , wherein - the internal combustion engine (2.1) has two four-stroke cylinders (2.2) working with a uniform ignition interval of 360° and an additional, larger expansion cylinder (2.3) for a subsequent expansion of the exhaust gas mixture of the four-stroke cylinders, wherein - the expansion cylinder (2.3) alternately consists of the two Combustion gases absorbed by four-stroke cylinders (2.2) are expanded in a two-stroke process, whereby - the gases are transferred from the four-stroke cylinders through openings (17) in a cylindrical wall of the expansion cylinder (2.3), in particular with a direction of flow approximately perpendicular to the cylinder axis. Drive unit for a motor vehicle according to one of Claims 1 until 5 , wherein at least one wall of the additional expansion cylinder (2.3) and/or one wall of the piston (11) guided in the expansion cylinder has a heat loss-reducing layer (T1, T2, T3, T4) made of a material whose thermal conductivity λ is lower than 200 W / (m*K), in particular lower than 50 W/ (m*K). Drive unit for a motor vehicle according to one of Claims 1 until 6 , wherein the internal combustion engine (2.1) is assigned a thermally effective insulation (50, 51, 52) in such a way that an internal temperature (MT) of the internal combustion engine of more than 100° C. under standard ambient conditions, in particular at an ambient temperature of 20° C., is less than 3 K per minute. Drive unit for a motor vehicle according to one of Claims 1 until 7 , wherein the exhaust lift valve (18) blocking the exhaust gas outlet (H, 20) of the expansion cylinder (2.3) is made entirely or partially of a ceramic material, the thermal conductivity λ of which is selected to be lower than 50 W/(m*K) . Drive unit for a motor vehicle according to one of Claims 1 until 8th , wherein the exhaust (lift) valve blocking the exhaust gas outlet (H, 20) of the expansion cylinder (2.3) has a main axis which is aligned parallel to the main axis (AH) of the expansion cylinder (2.3), preferably arranged to coincide with it. Drive unit for a motor vehicle according to one of Claims 1 until 9 , wherein - the internal combustion engine (2.1) has a first cylinder group with two four-stroke cylinders (2.2) working with equal ignition intervals and an additional expansion cylinder (2.3) for a subsequent expansion of the exhaust gas mixture of the four-stroke cylinders, wherein - the expansion cylinder (2.3) alternately consists of the two Combustion gases absorbed by four-stroke cylinders (2.2) are expanded, and wherein - the internal combustion engine has at least one second cylinder group which is designed essentially the same as the first cylinder group and in particular has a V shape, star shape or boxer shape with an angle greater than 0° to the first cylinder group is arranged inclined, wherein - the first and the second cylinder group drive a common output shaft (2.4). Motor vehicle, in particular passenger car (1) with a drive unit (2) according to one of Claims 1 until 10 . motor vehicle after claim 11 , wherein the drive unit (2), in particular the internal combustion engine (2.1), is assigned thermally effective insulation (50, 51, 52) in such a way that an internal temperature (MT) of the internal combustion engine (2.1) is more than 100° C. under standard ambient conditions (especially an air temperature of 20 ^C C) and falls by less than 3 K per minute in the case of a headwind flow with a flow speed of 80 km/h. Motor vehicle according to one of Claims 11 or 12 , wherein the internal combustion engine (2.1) has a first cylinder group with two four-stroke cylinders (2.2) and an additional expansion cylinder (2.3) for a subsequent expansion of the exhaust gas mixture of the four-stroke cylinders, the expansion cylinder (2.3) alternately expanding the combustion gases taken from the two four-stroke cylinders (2.2). , and wherein the cylinder group has a common exhaust gas outlet (20) and a subsequent common, thermally insulated exhaust gas pipe (6.1) whose radial thermal conductivity λ is designed to be lower than 50 W/(m*K). Motor vehicle according to one of Claims 11 until 13 , wherein - a catalytic converter (CC) is assigned to the internal combustion engine in the area of an exhaust pipe (6.1, 6.2), wherein - exhaust gas is taken from the exhaust pipe (6.2) downstream of the catalytic converter and routed to a heat exchanger (W) via targeted exhaust gas recirculation is transferred via the heat from the exhaust gas to the cooling water (2.8), wherein - the cooled exhaust gas is then either fed to the intake side (20B) of the internal combustion engine (2.1) or again to the exhaust pipe (6.2). Motor vehicle according to one of Claims 11 until 14 , wherein the drive unit (2) is designed as a serial hybrid system in such a way that the design power is less than or equal to the associated power value according to the driving resistance line (FK) of the motor vehicle on the level at a defined reference speed (vo _max ), in particular at 100 km /h, 125 km/h, at 145 km/h or 160 km/h.

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