Method for operating a drive system of a motor vehicle, in particular of a motor car

Abstract

The invention relates to a method for operating a drive system of a motor vehicle, wherein the drive system comprises an internal combustion engine having at least one combustion chamber and a gearbox which has a plurality of gears and via which the motor vehicle is driven by the internal combustion engine. A gearshift operation is carried out in which one of the gears is shifted to another of the gears. During the gearshift operation, a drive torque intended for propelling the motor vehicle, which is provided by the internal combustion engine, is temporarily reduced, wherein, in order to reduce the drive torque, the ignition timing of the internal combustion engine is retarded and a charge of the combustion chamber is reduced.

Description

[0001] 2024P01307WG

[0002] 1

[0003] Mercedes-Benz Group AG

[0004] Method for operating a drive unit of a motor vehicle, in particular a motor car

[0005] The invention relates to a method for operating a drive unit of a motor vehicle, in particular a motor car, according to the preamble of claim 1.

[0006] German patent DE 19727 044 A1 discloses a powertrain control system for a motor vehicle, comprising an engine and an automated transmission. The system includes an engine control unit that manages parameters influencing the engine's torque. It also includes a transmission control unit that manages the shifting operations of the automatic transmission and transmits an intervention signal to the engine control unit, enabling smooth gear changes.

[0007] The object of the present invention is to provide a method for operating a drive unit of a motor vehicle, such that switching operations of a transmission of the drive unit can be carried out in a particularly advantageous manner.

[0008] This problem is solved in the method with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0009] The invention relates to a method for operating a drive unit of a motor vehicle, also referred to simply as a vehicle, which is preferably designed as a motor car, in particular as a passenger car. Preferably, the method is driven while the motor vehicle is in motion, being driven by the drive unit during this journey. In the method, the drive unit comprises an internal combustion engine, also referred to as a combustion engine or internal combustion power unit. 2024P01307WG

[0010] 2

[0011] An internal combustion engine, which is designed, for example, as a reciprocating piston engine, i.e., as a reciprocating piston machine. The internal combustion engine has at least one combustion chamber. In particular, if the internal combustion engine is designed as a reciprocating piston engine, i.e., as a reciprocating piston machine, the combustion chamber is partially formed by a cylinder of the internal combustion engine. During firing operation of the internal combustion engine, combustion processes take place in the combustion chamber. In each combustion process, a mixture, also referred to as a fuel-air mixture, is burned, in particular ignited and combusted, wherein the mixture comprises air and a preferably liquid fuel. Preferably, the internal combustion engine is designed as a spark-ignition internal combustion engine, in particular as a gasoline engine.Preferably, the internal combustion engine is operated in fired mode during the process. In particular, the combustion processes in the combustion chamber proceed such that, within each operating cycle of the internal combustion engine, one of the combustion processes takes place. The internal combustion engine has, for example, an output shaft, which is in particular designed as a crankshaft. The output shaft is rotatable about an output shaft axis of rotation relative to a housing element of the internal combustion engine. For example, the housing element is a cylinder housing, in particular a cylinder crankcase, which, for example, includes, i.e., forms, the aforementioned cylinder. The combustion chamber is, for example, also partially formed, i.e., delimited, by a piston that is translationally movable within the cylinder.For example, the piston is articulated to the output shaft via a connecting rod, so that translational movements of the piston occurring in the cylinder and relative to the housing element can be converted into a rotary movement of the output shaft, which rotates around the output shaft axis relative to the housing element during its rotary movement.

[0012] In this method, the drive unit also includes a transmission, which is specifically designed as an automatic transmission. In particular, the transmission is designed as an automated manual transmission. In this method, the motor vehicle is driven by the internal combustion engine via the transmission. For this purpose, the internal combustion engine provides a drive torque via its output shaft.

[0013] 3. The transmission can provide a further torque resulting from the drive torque, by means of which the motor vehicle can be driven or is driven.

[0014] The transmission has several gears, also referred to as or designed as gear stages, which differ from one another, particularly in their gear ratios. For example, one gear has a first gear ratio and another has a second gear ratio, the second gear ratio being higher or, preferably, lower than the first gear ratio. The gears of the transmission are selectable gears. This means that each gear can be selected or disengaged. Specifically, it is provided that whenever one gear is engaged, the other gear is disengaged. Preferably, it is provided that whenever and, preferably, whenever the other gear is engaged, one gear is disengaged.In this process, the motor vehicle is driven or powered by the internal combustion engine via the currently engaged gear and thus via the respective gear ratio of that gear, particularly when the motor vehicle is not being driven by the internal combustion engine via the gear set and thus via the gear set. Thus, for example, the transmission converts the drive torque into the additional torque via the gear ratio of the currently engaged gear. Particularly when the other gear is engaged and the gear ratio of the other gear is higher than that of the first gear, the additional torque, and especially its magnitude, is lower than the drive torque and, in particular, its magnitude.Thus, for example, if one gear is engaged and the other gear is disengaged, and if the first gear ratio of one gear is greater than the second gear ratio of the other gear, the additional torque, in particular its magnitude, is greater than the drive torque, in particular its magnitude.

[0015] The process involves a gear change or shifting operation of the transmission, particularly automatically. During the shifting operation, the transmission changes from one gear to another, especially automatically. This means that during the shifting operation, the initially selected gear is 2024P01307WG.

[0016] 4. A gear, in particular automatic, is engaged and the other gear, in particular automatic, is engaged.

[0017] During the gear shift, the drive torque intended to propel the vehicle, which is supplied by the internal combustion engine, particularly via the output shaft, is temporarily reduced. This reduction of the drive torque, also referred to as reduction or torque reduction, is also called torque reduction or torque reduction.

[0018] In order to perform the switching process particularly advantageously, the invention provides that, to reduce the drive torque, the ignition timing of the internal combustion engine, also referred to as the ignition angle or designed as an ignition angle, is retarded, particularly temporarily, and that the filling of the combustion chamber is retarded, particularly temporarily, and that the filling of the combustion chamber is reduced, particularly temporarily. The ignition timing is the point in time at which, particularly within the respective operating cycle of the internal combustion engine, the respective mixture in the combustion chamber is ignited.Since, at the ignition point, the output shaft assumes a rotational position, particularly with respect to the output shaft's axis of rotation and the housing element, and this rotational position is also referred to as an angular position, the ignition point is also called the ignition angle, or the ignition point coincides with the rotational position and is therefore also called the ignition angle. Most preferably, the internal combustion engine is designed as a four-stroke engine, such that each working cycle of the internal combustion engine comprises exactly two complete revolutions of the output shaft and thus, in particular, exactly 720 degrees of crankshaft angle.

[0019] Especially when the combustion chamber is partially formed, and particularly limited, by the aforementioned cylinder, the filling is also referred to as cylinder filling. Reducing the filling refers to a reduction in the mass of air introduced into the combustion chamber, i.e., supplied to the combustion chamber, so that, in order to reduce the drive torque, not only is the ignition timing retarded, but the mass of air introduced into the combustion chamber is also reduced, particularly temporarily. 2024P01307WG

[0020] 5

[0021] In particular, the internal combustion engine has an intake manifold, also known as the intake tract, through which air flows into the combustion chamber. The intake manifold is also referred to as the air path, since the air, and thus the air mass, is introduced into the cylinder along this path.

[0022] Since the drive torque is temporarily reduced during the shifting process in the method according to the invention, the shifting process can be carried out very smoothly and almost without jerking or at least without interrupting the propulsion of the vehicle, and without excessive stress or even damage to the transmission. Since the invention provides that, to reduce the drive torque, not only is the ignition timing retarded, particularly temporarily, but also the combustion chamber filling is reduced, particularly temporarily, excessively high temperatures of the exhaust gas resulting from the combustion process of the internal combustion engine, and thus excessively high temperatures of components arranged in an exhaust tract of the internal combustion engine through which the exhaust gas flows, can be avoided.Furthermore, particularly low-emission and fuel-consumption operation of the internal combustion engine can be achieved, since the method according to the invention makes it possible to operate the internal combustion engine, especially during the entire switching process, continuously and thus without interruption, with a combustion air ratio greater than 0.95, particularly greater than 0.99, and most preferably at least 1.00. Thus, it is provided that the internal combustion engine, especially during the method, and particularly during the entire switching process, is operated with the combustion air ratio also referred to as lambda (A), which is greater than 0.95, particularly greater than 0.99, and most preferably at least or exactly 1.00.This eliminates the need for the fuel enrichment used in conventional methods for component cooling, thus enabling particularly low-emission and fuel-efficient operation of the internal combustion engine. Since both the ignition timing and the cylinder filling are retarded, particularly temporarily, to reduce drive torque, the ignition timing does not need to be retarded excessively compared to conventional methods. This reduces the efficiency reduction in the internal combustion engine that would otherwise result from retarding the ignition timing. Consequently, excessively high exhaust gas temperatures, also known as exhaust gas temperatures, can be avoided, thus preventing excessively high temperatures in the components located in the exhaust system.

[0023] To perform the switching process particularly advantageously, one embodiment of the invention provides that at least one component arranged in the intake tract is controlled, preferably automatically, to reduce the cylinder filling. This component influences the airflow through the intake tract. This means that the cylinder filling is reduced by means of the air path, such that the component is controlled. Thus, in this method, it is preferably provided that the ignition timing is retarded in a targeted or active manner and that the air path, and therefore the component, is actively or selectively controlled to reduce the cylinder filling, and thus the air mass, and thereby avoid excessively high exhaust gas temperatures.

[0024] One of the underlying insights of the invention is, in particular, that the air path alone cannot be used to reduce the drive torque during the shifting process. This is primarily due to the air path's inherent inertia, resulting in a comparatively long time lag between the activation of the air path—and thus the component intended to reduce the drive torque, and in particular the charge reduction—and the actual reduction of charge. This lag is too long to execute the shifting process quickly and thus with sufficient sportiness. In contrast, reducing the drive torque by retarding the ignition timing can be achieved much more quickly.Retarding the ignition timing leads to a decrease in the efficiency of the internal combustion engine and thus to an increase in the exhaust gas temperature. It was also found that, for example, if the reduction of the drive torque were achieved solely by retarding the ignition timing, and the internal combustion engine 2024P01307WG...

[0025] If the engine were operated with A = 1, this would result in very high exhaust gas temperatures, potentially so high that the temperature limits of components located in the exhaust system would be exceeded, causing these components to overheat. The aforementioned disadvantages and problems can now be avoided by the invention. By retarding the ignition timing, the torque reduction can be implemented sufficiently quickly. By reducing the cylinder charge, excessive retarding of the ignition timing can be avoided, thus preventing excessively high exhaust gas temperatures and, consequently, excessively high component temperatures of the components located in the exhaust system while the internal combustion engine is operated with A = 1.The invention is based in particular on the following findings and considerations: It is desirable to operate the internal combustion engine with a stoichiometric air-fuel ratio, i.e., with A = 1, in order to achieve low-emission and low-fuel-consumption operation of the internal combustion engine. Thus, the enrichment of the mixture intended to protect components, and therefore operation with A < 1, should be avoided.Operating an internal combustion engine with an air-fuel ratio (A = 1) inherently leads to a higher exhaust gas temperature compared to a substoichiometric air-fuel ratio. This means that components such as a turbocharger turbine and a catalytic converter located in the exhaust system are subjected to higher temperatures than they would be under a rich mixture (i.e., a substoichiometric air-fuel ratio). Without countermeasures, the component temperatures, particularly during steady-state full-load acceleration, will reach their respective maximum limits, which should not be exceeded to avoid excessive stress on the components.As soon as transient processes occur, particularly during acceleration, the maximum limits may be exceeded, and component damage can result if no countermeasures are taken. Such transient processes include, for example, shifting operations of a transmission, especially an automatic transmission. Here, the drive torque, which is configured as full-load torque, is temporarily and briefly reduced to enable the shifting operation to be carried out with virtually no component stress or interruption of traction. Therefore, it is preferably intended that the shifting operation be a 2024P01307WG.

[0026] 8

[0027] Upshifting is, therefore, an upshift in a train operation of the internal combustion engine, whereby in the upshifting a change is made from one gear to the other gear and where, for example, the second gear ratio of the other gear is lower than the first gear ratio of the first gear.

[0028] Traditionally, the rapid and transient reduction of drive torque, also known as torque reduction, is achieved primarily by retarding the ignition timing. However, this torque reduction solely through retarding the ignition angle reduces the efficiency of the internal combustion engine and significantly increases the exhaust gas temperature. Another way to reduce drive torque would be to use only the air intake for this purpose.However, reducing the drive torque solely by means of the air path cannot be used for gear shifts, i.e., for gear shifting operations, since there are physical limits regarding the speed at which the shifting process is carried out, in particular regarding how quickly the drive torque can be reduced and subsequently built up again, i.e., increased.If, on the one hand, there is a desire to operate the internal combustion engine with A = 1, and on the other hand, a desire to perform the gear changes quickly and thus sportily, thereby achieving torque reduction, in particular solely by retarding the ignition timing, then, to avoid excessively high exhaust gas temperatures, only a derating function remains. This function limits the drive torque, especially temporarily, to a value lower than the maximum value permitted, for example, during normal operation of the internal combustion engine, whereby, for instance, no gear changes occur during normal operation. By limiting the drive torque, the internal combustion engine and the components located in the exhaust system can be protected from excessively high temperatures, as excessive exhaust gas temperatures can be avoided.However, performing the derating function, also known as derating, is undesirable and should be avoided as much as possible, since it reduces the available power for propelling the vehicle. As previously described, the invention allows for advantageously fast and therefore sporty gear changes, while simultaneously preventing excessively high exhaust gas temperatures and enabling the combustion engine to operate with a stoichiometric air-fuel ratio. Therefore, the derating described above can be avoided.

[0029] To make the switching process particularly advantageous, a further embodiment of the invention provides that the component arranged in the intake tract has a throttle valve which is moved to its closed position, or towards its closed position, by actuating the component. This reduces the flow cross-section, at least partially limited by the throttle valve and accessible to the air flowing through the intake tract, which is, for example, the smallest flow cross-section of the intake tract accessible to the air flowing through it, thereby advantageously reducing the cylinder filling.

[0030] Another embodiment is characterized by the fact that the component, which is arranged in the intake tract, has a bypass valve which is moved into its open position or towards its open position by actuation. This allows the charge, and thus the air mass, to be advantageously reduced, so that excessively high exhaust gas temperatures are avoided, the drive torque is quickly reduced, and thus the gear shift can be carried out quickly and sportily.

[0031] In a further, particularly advantageous embodiment of the invention, the component arranged in the intake tract has at least one intake valve associated with the combustion chamber, the stroke of which is reduced by actuation. Thus, for example, the internal combustion engine has a variable valve train comprising the intake valve, whereby air can be introduced into the combustion chamber via the intake valve. By, for example, reducing the stroke of the intake valve, the cylinder filling can be reduced effectively and efficiently.

[0032] In a further, particularly advantageous embodiment of the invention, the component arranged in the intake tract comprises at least one compressor of an exhaust gas turbocharger, the speed of which is reduced by control. Thus, for example, the internal combustion engine has an exhaust gas turbocharger that is supplied with the exhaust gas of the internal combustion engine via a 2024P01307WG

[0033] 10

[0034] The turbine drives the compressor. The exhaust gas turbocharger can incorporate a wastegate, which allows at least partial bypassing of the turbine with exhaust gas. This reduces the amount of exhaust gas flowing through the turbine, thus lowering the turbocharger's speed and consequently reducing the amount of air drawn from the compressor to the internal combustion engine via the intake manifold. Alternatively or additionally, the exhaust gas turbocharger can include an electric motor. This motor allows for independent adjustment of the turbocharger's speed, and therefore the compressor's speed, based on the exhaust gas flow from the internal combustion engine. An exhaust gas turbocharger with an electric motor is also referred to as an eATL (electrically driven exhaust gas turbocharger).

[0035] To enable particularly fast and thus sporty shifting, a further embodiment of the invention provides for a transmission control unit to be assigned to the transmission, by means of which the transmission is controlled and thereby operated. In this method, the transmission control unit controls the transmission, thereby carrying out, i.e., effecting, the shifting process. For example, the transmission control unit controls transmission elements of the transmission to carry out the shifting process. The transmission control signal provides, for example, at least one, in particular electrical, transmission control signal to control the transmission and subsequently carry out the shifting process, with the transmission receiving the transmission control signal.

[0036] Furthermore, it is stipulated that the internal combustion engine is assigned an engine control unit (ECU) by which the engine is controlled and thus operated. The transmission control unit is also referred to as the first control unit. The engine control unit is also referred to as the second control unit. Each control unit is an electronic computing device.

[0037] In particular, it is provided that the first control unit is provided in addition to the second control unit. Preferably, the second control unit is provided in addition to the first control unit. Preferably, the first control unit is arranged outside of the second control unit. For example, the second control unit is arranged outside of the first control unit.

[0038] In this process, the transmission control unit sends out a request signal, in particular an electrical one. This means that the transmission control unit provides the request signal. Through this request signal, the transmission control unit instructs the engine control unit to retard the ignition timing and reduce the cylinder charge. The engine control unit receives the request signal. Depending on the request signal, that is, depending on whether the request signal has been received, the engine control unit sends out a control signal, in particular an electrical one, also referred to as an engine control signal. This means that the engine control unit provides the control signal. Using this control signal, the internal combustion engine is controlled in such a way that the ignition timing is retarded and the cylinder charge is reduced.Thus, the internal combustion engine receives the control signal, particularly the electrical one. This control signal, for example, activates actuators within the internal combustion engine, thereby retarding the ignition timing and reducing the cylinder charge. It is evident that, on the one hand, the transmission control unit controls the transmission to perform the shifting process. On the other hand, the transmission control unit sends a request to the engine control unit to reduce the cylinder charge and retard the ignition timing. The transmission control unit contains the necessary data for targeted torque reduction and torque control during gear changes, enabling rapid gear shifts.The transmission control unit is thus able to adjust the air demand, including a reduction in charge, precisely at the start of the shift, based on the shift time and the inertia of the air control system. In this way, the transmission control unit acts as the master, initiating the shift process and essentially instructing the internal combustion engine to reduce the charge and retard the ignition timing. The engine control unit, in turn, acts as a slave, receiving the request signal from the master as a command and implementing it. This ensures that the engine control unit reduces the charge and retards the ignition timing.In this embodiment, the transmission control unit utilizes the fact that it knows the timing of the shift process, i.e., the points in time at which its own shift should begin and end, when the cylinder charge should already be reduced, and when the ignition timing should already be retarded. Knowing these points in time, it instructs the engine control unit to reduce the cylinder charge and retard the ignition timing. This allows the shift process to be carried out quickly and sportily. 2024P01307WG.

[0039] 12

[0040] For example, the transmission control unit receives a shift request signal, particularly an electrical one, and then, depending on this signal, sends out the shift request signal, thus providing it. Subsequently, the engine control unit can receive this request signal and, depending on its reception, control the internal combustion engine to reduce the cylinder filling and retard the ignition timing.The transmission control unit controls the transmission based on the shift request signal, i.e., based on the receipt of the shift request signal, in order to execute the shift, specifically after the reduction of the cylinder charge and after the ignition timing has been retarded. This allows the shift to be carried out sufficiently quickly and thus advantageously sportily, and the internal combustion engine can be operated at A = 1, while simultaneously avoiding excessively high exhaust gas temperatures and thus excessively high temperatures of components located in the exhaust system.

[0041] For example, the switching request signal, particularly the electrical signal, is sent, i.e., provided, by the engine control unit. Furthermore, it is conceivable that the switching request signal is sent, i.e., provided, by a third control unit.

[0042] To perform the shifting process particularly efficiently, a further embodiment of the invention provides that at least part of the shifting process is carried out while the ignition timing is retarded and the cylinder charge is reduced. It has proven particularly advantageous to retard the ignition timing and reduce the cylinder charge before performing at least part of the shifting process. This effectively avoids excessive stress on the internal combustion engine, the transmission, and components located in the exhaust system, and allows the shifting process to be performed quickly and thus in a sporty manner. Another embodiment is characterized by the fact that, after retarding the ignition timing and reducing the cylinder charge, the ignition timing is advanced and the cylinder charge is increased.This allows the shifting process, particularly as an upshift, to be carried out very efficiently and thus almost without interruption of traction. For example, after the ignition timing is retarded and the cylinder charge is reduced, and especially after at least part of the shifting process, the transmission control unit provides a second request signal, particularly an electrical one, which the transmission control unit uses to request the engine control unit to advance the ignition timing and increase the cylinder charge. As with torque reduction, the transmission control unit has the necessary data for targeted torque build-up and torque control during a shift between gears for a rapid gear change.The transmission control unit is thus able to adjust the air demand with a targeted increase in charge towards the end of the shift, based on the shift time and the inertia of the air control system, and to control the torque at the end of the shift or gear change to ensure a corresponding, appropriate torque for engaging the selected gear. The engine control unit receives the second demand signal, which is primarily electrical. Depending on this second demand signal, the engine control unit then controls the internal combustion engine, specifically as described above, thereby advancing the ignition timing and increasing the charge.

[0043] To enable a fast and sporty shifting process while avoiding excessive stress on components, a further embodiment of the invention provides that, after at least part of the shifting process has been completed, including retarding the ignition timing and reducing the cylinder charge, the ignition timing is advanced and the cylinder charge is increased. This allows the shifting process to be carried out quickly and with virtually no interruption in traction.

[0044] Also disclosed is a motor vehicle, also simply referred to as a vehicle and preferably designed as a motor car, in particular a passenger car, which is configured to carry out a method according to the invention. Advantages and advantageous embodiments of the method according to the invention are to be regarded as advantages and advantageous embodiments of the motor vehicle and vice versa.

[0045] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0046] The drawing shows in:

[0047] Fig. 1 is a diagram illustrating a method for operating a drive unit of a motor vehicle; and

[0048] Fig. 2 shows another diagram to further illustrate the process.

[0049] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0050] The following describes a method for operating a drive unit of a motor vehicle, also referred to simply as a vehicle, with reference to Figures 1 and 2. Figure 1 shows a diagram with two abscissas 10 and 12, on which time is plotted, increasing from left to right relative to the plane of Figure 1. A drive torque, in units [Nm], is plotted on a first ordinate 14 of the diagram, increasing from bottom to top relative to the plane of Figure 1. A temperature is plotted along a second ordinate 16 of the diagram, increasing from bottom to top relative to the plane of Figure 1.

[0051] In this method, the drive unit comprises an internal combustion engine, also referred to as a combustion engine or internal combustion power unit, which has at least one combustion chamber. In this method, the internal combustion engine is located in 2024P01307WG.

[0052] 15. The internal combustion engine is operated in a fired state in which combustion processes take place in the combustion chamber, such that exactly one of the combustion processes occurs within each operating cycle of the internal combustion engine. In each combustion process, a specific mixture, also referred to as a fuel-air mixture, is ignited and burned, with the respective mixture being ignited at a specific ignition point, also referred to as the ignition angle, within each operating cycle. The mixture comprises air and a preferably liquid fuel. The internal combustion engine has an intake manifold, also referred to as the inlet manifold, through which air flows.Air is supplied to the combustion chamber via the intake manifold, i.e., introduced into the combustion chamber, specifically within each combustion cycle, such that a specific mass of air, also referred to as air mass, is introduced into the combustion chamber during each combustion cycle. The internal combustion engine has a housing element, also called a cylinder housing, which contains, i.e., forms, a cylinder. The combustion chamber is partially formed, i.e., partially bounded, by the cylinder and partially by a piston that is movably mounted within the cylinder. The internal combustion engine has an output shaft designed as a crankshaft, which is rotatable about an output shaft axis relative to the housing element.The piston is articulated to the output shaft via a connecting rod, so that translational movements occurring in the cylinder and relative to the housing element, in particular reciprocating movements of the piston, are converted into a rotational movement of the output shaft. During this rotational movement, the output shaft rotates around its axis of rotation relative to the housing element. Specifically, the internal combustion engine is operated in its fired state during this process. The piston, and thus the output shaft via the connecting rod, is driven by the respective combustion process, causing the output shaft to rotate around its axis of rotation relative to the housing element. In this process, the internal combustion engine provides a drive torque, intended or designed for propelling the motor vehicle, via the output shaft. Exhaust gas from the internal combustion engine results from the combustion processes.

[0053] In this process, the vehicle is driven by the internal combustion engine via the transmission. The transmission has several gears that differ in their ratios, so that one of the gears has a 2024P01307WG

[0054] 16. The first gear ratio and another gear ratio have a second gear ratio, which is higher or, preferably, lower than the first gear ratio. The transmission is an automatic transmission, in particular an automated manual transmission. The motor vehicle is driven via the transmission by means of the internal combustion engine in such a way that the internal combustion engine provides the drive torque via the output shaft, through which the drive torque is introduced into the transmission. In the method, one gear is initially engaged and the other gear is disengaged.

[0055] In this process, a gear shift, particularly an automatic one, is performed, during which the vehicle changes from one gear to another, thus disengaging the previously engaged gear and engaging the previously engaged gear. Furthermore, during this shift, the drive torque intended for propelling the vehicle, i.e., the torque supplied by the internal combustion engine via the output shaft, is temporarily reduced. This reduction of the drive torque, also referred to as torque reduction, torque dissipation, or torque reduction, is also known as torque reduction.

[0056] For example, a transmission control unit is assigned as the first control unit to the transmission, and for example, an engine control unit is assigned as the second control unit to the internal combustion engine.

[0057] At an initial time point T1, the transmission control unit receives a shift request signal, particularly an electrical one, which prompts the transmission control unit to initiate the shift operation. Depending on this shift request signal, the transmission control unit provides a request signal, also particularly an electrical one. This means that the transmission control unit sends out the request signal. The engine control unit receives this request signal. Through this signal, the transmission control unit requests the engine control unit to retard the ignition timing and reduce the combustion chamber charge. Since the combustion chamber is partially defined by the cylinder, this charge is also referred to as cylinder charge.Reducing the fill level includes reducing the 2024P01307WG.

[0058] 17. The air mass mentioned above is the mass introduced into the combustion chamber, i.e., supplied to the combustion chamber, during the respective operating cycle. Depending on the request signal, i.e., depending on the receipt of the request signal, the engine control unit provides a first request signal, in particular an electrical one. This means that the engine control unit sends out the first control signal. By means of the first control signal, the internal combustion engine is controlled in such a way that the ignition timing is retarded and the charge, and thus the air mass, is reduced.It is evident that the request signal is a request or instruction from the engine control unit to the engine control unit, whereby the engine control unit complies with or follows this instruction by controlling the internal combustion engine by means of the first control signal and thereby causing the reduction of the charge and the retardation of the ignition timing.

[0059] Furthermore, it is intended that the transmission control unit, depending on the shift request signal, that is, depending on the receipt of the shift request signal, controls the transmission, thereby carrying out, i.e., effecting, the shifting process. For this purpose, the transmission control unit provides, for example, a second control signal, particularly an electrical one. For example, the internal combustion engine receives the first control signal, which controls the engine in such a way that the cylinder filling is reduced and the ignition timing is retarded. The transmission receives, for example, the second control signal, particularly an electrical one, thereby carrying out, i.e., effecting, the shifting process. It is conceivable that the engine control unit provides, i.e., transmits, a warning signal, particularly an electrical one. The transmission control unit receives, for example, this warning signal, particularly an electrical one.It is conceivable that the transmission control unit also controls the transmission depending on the indicator signal, i.e., also depending on the receipt of the indicator signal, thereby initiating or effecting the shifting process. For example, the transmission control unit could provide a second control signal, also depending on the indicator signal, i.e., also depending on the receipt of the indicator signal, by means of which the transmission is controlled in such a way that the shifting process is carried out, and thus the initially engaged gear is disengaged and the initially engaged gear is engaged. (Part number 2024P01307WG)

[0060] 18

[0061] The warning signal characterizes, for example, the reduction of the cylinder filling, which has actually occurred, and the retardation of the ignition timing, which has actually occurred, so that, for example, at least part of the shifting process is carried out by controlling the transmission while the cylinder filling is reduced and the ignition angle is retarded.

[0062] The request signal is illustrated in Fig. 1 by a first waveform V1. The request signal characterizes, for example, a target value of the drive torque, so that, for instance, the transmission control unit requests the engine control unit to reduce the drive torque in such a way that the request signal characterizes or specifies the target value of the drive torque, which is, so to speak, requested by the engine control unit. In other words, the transmission control unit uses the request signal to instruct the engine control unit to control and thus operate the internal combustion engine in such a way that the drive torque, i.e., an actual value of the drive torque, corresponds to the target value.It is evident that, for example, reducing the drive torque is specified by defining a target value, so that the transmission control unit requests the engine control unit to retard the ignition timing and reduce the cylinder charge using this target value. The target value of the drive torque is illustrated by curve V2. For example, curve V2 illustrates the warning signal. This warning signal is, for instance, feedback from the engine control unit to the transmission control unit, informing the transmission control unit that the cylinder charge has been reduced, the ignition timing retarded, and thus the drive torque has been reduced, thereby fulfilling the request to reduce the drive torque. Curve V3 illustrates a so-called air torque specification from the transmission control unit to the engine control unit.The air torque setting is a specification of a so-called air torque. The air torque is a torque theoretically available from the internal combustion engine via the output shaft, which would be provided by the internal combustion engine via the output shaft if the ignition timing were optimally positioned within the respective operating cycle with regard to the efficiency of the internal combustion engine. Figure V4 illustrates a result that results from the air torque and from retarding the ignition timing compared to the optimal ignition timing position. 2024P01307WG.

[0063] 19

[0064] Since the ignition timing is retarded compared to its optimal position for the efficiency of the internal combustion engine, a lower torque is converted than the full air torque. A hatched area F illustrates the amount of heat contained in the exhaust gas, resulting from the retarded ignition timing and reduced charge during the switching process. Thus, the hatched area F represents the exhaust gas temperature, also known as the exhaust gas temperature, resulting from the retarded ignition timing and reduced charge. This temperature is illustrated by the curve V5.A straight line and a line 18 running parallel to the abscissa 12 illustrates a limit temperature that should not be exceeded by the exhaust gas temperature illustrated by the curve V5 in order to avoid excessively high temperatures of components located in an exhaust gas tract through which the exhaust gas flows.

[0065] Figure 1 also shows curve V6, which is a comparative curve. It can be seen that, because the drive torque is temporarily reduced in this method by not only retarding the ignition timing but also reducing the cylinder charge, exceeding the limit temperature via curve V5, and thus by the exhaust gas temperature, can be avoided. At the same time, the internal combustion engine can be operated continuously, and therefore without interruption, with a stoichiometric air-fuel ratio (A = 1) during the shifting process. Since the reduction of the drive torque is also achieved by retarding the ignition timing, the drive torque can be reduced quickly, allowing for a fast and therefore sporty shifting process.At the same time, excessively high exhaust gas temperatures, and thus excessively high temperatures of components located in the exhaust system, are avoided. Furthermore, by operating the internal combustion engine with a stoichiometric air-fuel ratio, low-emission and low-fuel-consumption operation can be ensured.

[0066] For example, it is provided that, in order to reduce the filling, at least one component arranged in the intake tract is controlled, in particular automatically, whereby the component influences the airflow through the intake tract. Thus, for example, the component arranged in the intake tract is controlled by the first control signal. For example, the component 2024P01307WG comprises

[0067] 20. A throttle valve, which is closed by actuating the component. Alternatively or additionally, the component includes, for example, a diverter valve, which is opened by actuating the component. Alternatively or additionally, the component includes, for example, an intake valve associated with the combustion chamber, the lift of which is reduced by actuating the component, and / or at least one compressor of an exhaust gas turbocharger, the speed of which is reduced by actuating the component.

[0068] Preferably, at least the aforementioned part of the switching process is carried out while the ignition timing is retarded and the charge is reduced. Preferably, the ignition timing is retarded and the charge is reduced before at least part of the switching process is carried out. Preferably, after retarding the ignition timing and reducing the charge, the ignition timing is advanced and the charge is increased, particularly such that after carrying out at least part of the switching process, and thus after retarding the ignition timing and reducing the charge, the ignition timing is advanced and the charge is increased.For this purpose, the transmission control unit, for example, provides a second request signal, particularly an electrical one, especially after at least part of the shifting process has been completed. This means the transmission control unit sends out the second request signal. This allows a torque build-up to be initiated. The engine control unit receives this second request signal. Depending on this second request signal, the engine control unit then controls the internal combustion engine, for example, by increasing the cylinder charge and advancing the ignition timing.Thus, for example, the engine control unit, depending on the second request signal—that is, depending on the receipt of the second request signal—provides a third control signal, particularly an electrical one, by means of which the internal combustion engine is controlled in such a way that the charge is increased and the ignition timing is advanced. Thus, for example, the internal combustion engine receives the third control signal.

[0069] Fig. 2 shows a diagram on whose abscissa 20 is the rotational speed of the internal combustion engine, i.e., the rotational speed of the output shaft, which rotates or can rotate around the output shaft's axis of rotation relative to the housing element at that rotational speed. The drive torque is illustrated on an ordinate 22. A characteristic map 24 of the internal combustion engine, also referred to as an engine map, is plotted in the diagram shown in Fig. 2. In Fig. 1, a region of the characteristic map 24 is illustrated by B1, whereby, for example, the method is carried out, in particular only, in region B1 and thus only at high loads, at full load, and at high rotational speeds. This advantageously avoids excessive exhaust gas temperatures, and thus excessively high temperatures of components located in the exhaust system, particularly during full-load operation of the internal combustion engine.

[0070] Reference symbol list

[0071] 10 Abscissa

[0072] 12 Abscissa

[0073] 14 ordinates

[0074] 16 ordinates

[0075] Line 18

[0076] 20 Abscissa

[0077] 22 ordinates

[0078] 24 characteristic map

[0079] B1 area

[0080] F area

[0081] T 1 Time

[0082] V1 progress

[0083] V2 progress

[0084] V3 progress

[0085] V4 history

[0086] V5 progress

[0087] V6 history

Claims

2024P01307WG 23 Mercedes-Benz Group AG Patent claims 1. Method for operating a propulsion device of a motor vehicle, wherein: - the drive system comprises an internal combustion engine having at least one combustion chamber and a transmission having several gears, through which the motor vehicle is driven by the internal combustion engine; - a gear shift is performed, in which the vehicle changes from one gear to another; and - during the shifting process, a drive torque intended to propel the motor vehicle, which is provided by the internal combustion engine, is temporarily reduced; characterized in that - to reduce the drive torque, the ignition timing of the internal combustion engine is retarded and the filling of the combustion chamber is reduced; - a transmission control unit is assigned to the transmission, by means of which the transmission is controlled and thereby operated; - the transmission control unit controls the transmission, thereby carrying out the shifting process; - the internal combustion engine is assigned an engine control unit by means of which the internal combustion engine is controlled and thereby operated; - the transmission control unit sends out a request signal, by which the transmission control unit requests the engine control unit to retard the ignition timing and reduce the fuel injection; - the engine control unit receives the request signal and, depending on the request signal, sends out a control signal by means of which the The internal combustion engine is controlled in such a way that the ignition timing is retarded and the cylinder filling is reduced; and. - at least part of the switching process is carried out while the ignition timing is retarded and the fuel charge is reduced.

2. The method according to claim 1, characterized in that: - the internal combustion engine has an intake manifold through which air is drawn into the combustion chamber; and - to reduce the filling, at least one component located in the intake tract is controlled, whereby the component influences the flow of air through the intake tract.

3. Method according to claim 2, characterized in that the component has a throttle valve which is moved into its closed position or in the direction of its closed position by actuation.

4. Method according to claim 2 or 3, characterized in that the component has a bypass valve which is moved into its open position or in the direction of its open position by actuation.

5. Method according to one of claims 2 to 4, characterized in that the component has at least one inlet valve associated with the combustion chamber, the stroke of which is reduced by actuation.

6. Method according to one of claims 2 to 5, characterized in that the component has at least one compressor of an exhaust gas turbocharger, the speed of which is reduced by control.

7. Method according to one of the preceding claims, characterized in that Before at least part of the switching process is carried out, the ignition timing is retarded and the fuel mixture is reduced.

8. Method according to one of the preceding claims, characterized in that after setting the ignition timing to late and after reducing the filling, the ignition timing is set to early and the filling is increased.

9. Method according to claim 8, characterized in that after performing at least part of the switching process and thereby after setting the ignition timing to late and after reducing the filling, the ignition timing is set to early and the filling is increased.

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