METHOD FOR OPERATING A POWERTRAIN OF A MOTOR VEHICLE, IN PARTICULAR A TRUCK, AND MOTOR VEHICLE

Abstract

A method for operating a powertrain, having at least one drive motor and at least one gearbox, of a motor vehicle which can be driven by the drive motor, via the gearbox, in which heat is transferred from the drive motor to the gearbox in a targeted manner, as a result of which the gearbox is heated in a targeted manner The heat is transferred from the drive motor to the gearbox in a targeted manner on the basis of predictive data which include at least one future state of the motor vehicle.

Claims

1-10. (canceled)

11. A method for operating a powertrain, comprising: at least one drive motor and at least one gearbox, of a motor vehicle which can be driven by the drive motor, via the gearbox, in which heat is transferred from the drive motor to the gearbox in a targeted manner, as a result of which the gearbox is heated in a targeted manner, wherein heat is transferred from the drive motor to the gearbox in a targeted manner on the basis of predictive data which include at least one future state of the motor vehicle.

12. The method according to claim 11, wherein heat is also transferred from the drive motor to the gearbox in a targeted manner as a function of at least one efficiency value, which is particularly stored in a storage device of an electronic computing device of the powertrain, wherein the efficiency value includes a level of efficiency and/or a power loss of the gearbox.

13. The method according to claim 11, wherein heat is transferred from the drive motor to the gearbox in a targeted manner also as a function of at least one limit value, which is particularly stored in a storage device of an electronic computing device of the powertrain, wherein the limit value includes a maximum permissible temperature of the gearbox.

14. The method according to claim 11, wherein the predictive data include at least one future driving speed of the motor vehicle and/or at least one future load of the drive motor and/or at least one future rotational speed of the drive motor and/or at least one future temperature of the drive motor and/or at least one future temperature of the gearbox and/or a course of a driving route ahead of the motor vehicle and/or a future speed limit which applies to the motor vehicle and/or a future switch-off point of the drive motor and/or a destination, which the motor vehicle will reach in the future, and/or a temporary switch-off phase of the drive motor.

15. The method according to claim 11, wherein at least one part of the predictive data is determined by data which the motor vehicle receives wirelessly, from at least one electronic computing device, which is external to the motor vehicle, and/or in that at least one part of the predictive data is determined by data which are stored in a storage device of an electronic computing device of the powertrain.

16. The method according to claim 11, wherein the targeted transfer of heat from the drive motor to the gearbox is the heat from the drive motor transferred to at least one first medium for cooling the drive motor, heat transferred from the first medium, via at least one heat exchanger, to at least one second medium, and heat transferred from the second medium to the gearbox, in a particularly targeted manner.

17. The method according to claim 16, wherein the targeted transfer of heat from the drive motor to the gearbox is a temperature of the first medium increased in a targeted manner.

18. The method according to claim 17, wherein the targeted increase in temperature of the first medium includes the drive motor operated in a targeted manner in order to effect the increase in temperature of the first medium in a targeted manner

19. The method according to claim 16, wherein the targeted transfer of heat from the drive motor to the gearbox is at least one flow of the first medium and/or of the second medium set in a targeted manner by the heat exchanger.

20. A motor vehicle with a powertrain having an electronic computing device, at least one drive motor, and at least one gearbox, by which the motor vehicle can be driven by the drive motor, wherein the computing device is formed to effect a targeted transfer of heat from the drive motor to the gearbox and thereby targeted heating of the gearbox is effected, wherein the computing device is formed to transfer heat from the drive motor to the gearbox in a targeted manner as a function of predictive data, which includes at least one future state of the motor vehicle.

21. The method according to claim 12, wherein heat is transferred from the drive motor to the gearbox in a targeted manner also as a function of at least one limit value, which is particularly stored in a storage device of an electronic computing device of the powertrain, wherein the limit value includes a maximum permissible temperature of the gearbox.

22. The method according to claim 12, wherein the predictive data include at least one future driving speed of the motor vehicle and/or at least one future load of the drive motor and/or at least one future rotational speed of the drive motor and/or at least one future temperature of the drive motor and/or at least one future temperature of the gearbox and/or a course of a driving route ahead of the motor vehicle and/or a future speed limit which applies to the motor vehicle and/or a future switch-off point of the drive motor and/or a destination, which the motor vehicle will reach in the future, and/or a temporary switch-off phase of the drive motor.

23. The method according to claim 13, wherein the predictive data include at least one future driving speed of the motor vehicle and/or at least one future load of the drive motor and/or at least one future rotational speed of the drive motor and/or at least one future temperature of the drive motor and/or at least one future temperature of the gearbox and/or a course of a driving route ahead of the motor vehicle and/or a future speed limit which applies to the motor vehicle and/or a future switch-off point of the drive motor and/or a destination, which the motor vehicle will reach in the future, and/or a temporary switch-off phase of the drive motor.

24. The method according to claim 12, wherein at least one part of the predictive data is determined by data which the motor vehicle receives wirelessly, from at least one electronic computing device, which is external to the motor vehicle, and/or in that at least one part of the predictive data is determined by data which are stored in a storage device of an electronic computing device of the powertrain.

25. The method according to claim 13, wherein at least one part of the predictive data is determined by data which the motor vehicle receives wirelessly, from at least one electronic computing device, which is external to the motor vehicle, and/or in that at least one part of the predictive data is determined by data which are stored in a storage device of an electronic computing device of the powertrain.

26. The method according to claim 14, wherein at least one part of the predictive data is determined by data which the motor vehicle receives wirelessly, from at least one electronic computing device, which is external to the motor vehicle, and/or in that at least one part of the predictive data is determined by data which are stored in a storage device of an electronic computing device of the powertrain.

27. The method according to claim 12, wherein the targeted transfer of heat from the drive motor to the gearbox is the heat from the drive motor transferred to at least one first medium for cooling the drive motor, heat transferred from the first medium, via at least one heat exchanger, to at least one second medium, and heat transferred from the second medium to the gearbox, in a particularly targeted manner.

28. The method according to claim 13, wherein the targeted transfer of heat from the drive motor to the gearbox is the heat from the drive motor transferred to at least one first medium for cooling the drive motor, heat transferred from the first medium, via at least one heat exchanger, to at least one second medium, and heat transferred from the second medium to the gearbox, in a particularly targeted manner.

29. The method according to claim 14, wherein the targeted transfer of heat from the drive motor to the gearbox is the heat from the drive motor transferred to at least one first medium for cooling the drive motor, heat transferred from the first medium, via at least one heat exchanger, to at least one second medium, and heat transferred from the second medium to the gearbox, in a particularly targeted manner.

30. The method according to claim 15, wherein the targeted transfer of heat from the drive motor to the gearbox is the heat from the drive motor transferred to at least one first medium for cooling the drive motor, heat transferred from the first medium, via at least one heat exchanger, to at least one second medium, and heat transferred from the second medium to the gearbox, in a particularly targeted manner.

Description

[0030] An exemplary embodiment of the invention is described in the following. The following is shown:

[0031] FIG. 1 a schematic representation of a powertrain of a motor vehicle according to the invention, wherein the powertrain is formed for implementing a method according to the invention; and

[0032] FIG. 2 diagrams to illustrate the method.

[0033] The exemplary embodiment explained in the following refers to a preferred embodiment of the invention. With the exemplary embodiment, the described components of the embodiment represent individual features to be considered independently of one another, which also further embody the invention independently of one another. Thus, the disclosure should also comprise combinations of the features of the embodiment other than those shown. Furthermore, the described embodiment can also be supplemented through further described features of the invention.

[0034] The same reference numerals refer to equivalent features and functions in the figures.

[0035] FIG. 1 shows, in a schematic representation, a powertrain 10 of a motor vehicle, particularly of a truck such as, for example, a passenger car. A method for operating the powertrain 10 is described in the following by means of FIGS. 1 and 2. The powertrain 10 has at least one drive motor 12, which is formed, for example, as a combustion engine. The drive motor 12 comprises, for example, a first housing element 14 and a second housing element 16, wherein the housing elements 14 and 16 can be formed separately from one another and may be connected to one another. Housing element 14, for example, is a crank housing, particularly a cylinder crank housing, wherein housing element 16, for example, is a cylinder head. Housing element 14 forms, for example, at least one or more combustion chambers, which may be formed as cylinders. During fueled operation of the combustion engine, combustion processes are occurring in the respective combustion chamber. The aforementioned method in this case is implemented during a trip of the motor vehicle and/or during fueled operation.

[0036] The drive motor 12, particularly housing element 14 and/or housing element 16, is arranged in a first circuit, through which a first medium can flow. The first circuit, for example, is a cooling circuit, wherein the first medium, for example, is a cooling medium. The first medium is preferably a fluid, particularly a liquid. In particular, the liquid may be formed as water or at least contains water, such that the cooling medium, for example, can be cooling water. By means of the first medium, at least one part of the combustion engine and/or of the drive motor 12 can be cooled in that, for example, there is a transfer of heat from the drive motor 12 to the first medium. The drive motor 12 is hereby cooled, and the first medium is heated. FIG. 1 in this case has arrows indicating a respective transfer of heat and/or a respective transmission of heat. In particular, it is conceivable that heat from housing element 14 passes to housing element 16.

[0037] The drive motor 12 has an output shaft 18 formed, for example, as a crankshaft, by means of which the drive motor 12 can provide at least one torque, particularly for driving the motor vehicle, and/or it provides the torque during the method.

[0038] Moreover, the powertrain 10 comprises at least one gearbox 20, which can be coupled or is coupled with the drive motor 12, particularly with the output shaft 18. The torque provided by the drive motor 12 can thereby be applied to the gearbox 20, whereby the gearbox 20 can be driven or is driven. In this case, the motor vehicle can be driven by the drive motor 12, via the gearbox 20, and/or the motor vehicle is driven by the drive motor 12, via the gearbox 20, for example, during the method.

[0039] As explained in more detail in the following, heat is transferred from the drive motor 12 to the gearbox 20 in a targeted manner with the method, whereby the gearbox is heated in a targeted manner

[0040] The gearbox 20 is arranged, for example, in a second circuit, through which a second medium can flow. The second medium, for example, is a liquid. In particular, the second medium may be oil, which is also characterized as gearbox oil. In this case, a heat exchange can take place between the gearbox 20 and the second medium. In a first operating state, such a heat exchange takes place, for example, between the gearbox 20 and the second medium, such that heat passes from the gearbox 20 to the second medium. The gearbox 20 is hereby cooled, and the second medium is heated. In a second operating state, such a heat exchange can take place, for example, between the gearbox 20 and the second medium, such that heat passes from the second medium to the gearbox 20. The gearbox 20 is hereby heated, and the second medium is cooled.

[0041] The powertrain 10 also comprises at least one electronic computing device 22, which is especially schematically shown in FIG. 1, and which also is designated as a control unit. In this case, the method is implemented by means of the electronic computing device 22.

[0042] In order to then be able to implement an especially efficient and thus low-energy-consuming operation of the powertrain 10 and thus of the motor vehicle as a whole, heat is transferred from the drive motor 12 to the gearbox 20, particularly via the media, on the basis of predictive data which characterize at least one future state of the motor vehicle, particularly of the powertrain 10. In other words, the targeted transfer of heat from the drive motor 12 to the gearbox 20 is effected, by means of the electronic computing device 22, on the basis of predictive data which characterize at least one future state of the motor vehicle, particularly of the powertrain 10.

[0043] The first circuit also contains a heat exchanger designated as a cooling element 24, through which heat exchanger the first medium can flow. Air, particularly ambient air, for example, can flow around the cooling element 24. Particularly when the first medium is formed as a liquid, the cooling element 24 is formed, for example, as a liquid-to-air heat exchanger, because a heat exchange can take place between the air and the first medium via the cooling element 24. In particular, a transfer of heat from the first medium to the air takes place via the cooling element 24, whereby the first medium is cooled. As a result, the drive motor 12 can be cooled effectively.

[0044] Moreover, the powertrain 10 also has a heat exchanger 26 characterized as a gearbox heat exchanger, which is arranged, for example, in both the first circuit and in the second circuit. The first medium and the second medium can thereby flow through the heat exchanger 26. In particular, the first medium and the second medium can flow through the heat exchanger 26 during the method and, in doing so, particularly during the second operating state as well as optionally also during the first operating state. An exchange of heat can take place between the media via the heat exchanger 26. For example, because both media are formed as liquids, the heat exchanger 26 is formed, for example, as a liquid-to-liquid heat exchanger. During the method, such an exchange of heat between the media takes place via the heat exchanger 26 such that heat from the first medium passes to the second medium via the heat exchanger 26. The first medium is hereby cooled, and the second medium is heated. As a result, heat can pass from the heated second medium to the gearbox 20, whereby the gearbox 20 is heated. By means of the electronic computing device 22 in this case, the second operating state, in which heat from the drive motor 20 passes to the first media, heat from the first medium passes to the second medium via the heat exchanger 26, and heat passes from the second medium to the gearbox 20, can thus be set in a targeted manner and as desired, particularly by means of corresponding actuation of at least one component of the powertrain 10. The gearbox 20 can hereby be heated in a targeted manner

[0045] FIG. 2 shows diagrams 28 and 30, on the respective x-axes 32 of which time has been plotted. A temperature is plotted on the y-axis 34 of diagram 28, and a driving speed of the motor vehicle is plotted on the y-axis 36 of diagram 30. Thus, curve 38 illustrates the driving speed of the motor vehicle over time. Curve 40 illustrates a temperature of the first medium over time, and curve 42 illustrates a temperature of the gearbox oil over time. Parts of curve 40 shown as a dashed-and-dotted line illustrate, for example, the temperature of the first medium when the method is not implemented. Parts of curve 40 shown as solid lines illustrate the temperature of the first medium when the method is implemented. Accordingly, parts of curve 42 shown as dashed lines illustrate the temperature of the gearbox oil when the method is not implemented, and parts of curve 42 shown as solid lines illustrate the temperature of the gearbox oil when the method is implemented.

[0046] FIG. 2 shows future event detections and thus future states of the motor vehicle designated as Z, wherein—as shown in FIG. 2—the respective temperatures are raised in a targeted manner as a function of the future event detections Z. As a result, the gearbox 20 is heated in a targeted manner The gearbox 20 thereby has an especially high temperature, which is also designated as a restart temperature, for example, at a starting point in time S and a start phase SP subsequent thereto, such that the powertrain 10 as a whole has an advantageous restart temperature at the starting point in time S and during the start phase SP. As a result, the inner friction and thus losses of the powertrain 10 can be kept particularly low. In this case, the starting point in time S and the start phase SP follow, for example, a time interval, which is between the starting point in time S and a stopping point in time A. At the stopping point in time A, the drive motor 12 and the powertrain 10 and thus the motor vehicle are deactivated as a whole, wherein an activation of the motor vehicle is suppressed during the time interval.

[0047] As a whole, it can be discerned that an especially high quantity of heat can be stored in the gearbox 20 by means of the method in that the gearbox 20 is heated in a targeted manner The gearbox 20 is thus utilized as a heat accumulator in order to ensure an advantageously high temperature of the powertrain 10 at the starting point in time S. Due to the targeted heating of the gearbox 20, heat which otherwise is usually lost without being used is provisionally stored in the gearbox 20. In this case, the thermal mass of the gearbox 20 is utilized in that the gearbox 20 is heated via the gearbox oil heat exchanger. Enthalpy of the drive motor 12 is hereby stored in the gearbox. The additional stored enthalpy is stored during the time interval which is also characterized as the parking time in order to ensure a particularly high restart temperature. In particular, the gearbox 20 is heated parallel to the drive motor 12 simply characterized also as the motor. Furthermore, it is conceivable that several gearbox oil heat exchangers are provided, by means of which the gearbox 20 can be heated in a targeted manner The gearbox oil heated in the described manner can heat the gearbox 20, for example, such that a transfer of heat takes place from the gearbox oil to components of the gearbox 20. The additional enthalpy of the gearbox 20 then stored in the gearbox 20 means that the motor and the gearbox 20 cool down significantly more slowly during the time interval than they otherwise would with conventional powertrains. In other words, the motor and the gearbox have a higher restart temperature than they otherwise would have with conventional powertrains at a fixedly defined restart point in time (starting point in time S). The motor and the gearbox 20 are assemblies which are utilized as thermal accumulators or batteries.

[0048] Preferably, the gearbox 20 is heated in a targeted manner not only with consideration of the predictive data but also with knowledge of the gearbox power loss. Preferably, the thermal frictional power behavior of the motor as well as the coolant temperature are also included. This idea could also be applied as relates to an optimization of fan run-on times of the motor. By knowing or estimating the power loss or the efficiency level of the gearbox 20, the temperature change of the gearbox 20 can be calculated using the gearbox mass and the thermal capacity. The thermal function Q results in:

Q=M×cp×δT

[0049] In this case, M designates the mass of the gearbox, cp designates the thermal capacity of the gearbox 20 and/or the components thereof, and δT designates the temperature change. The thermal function Q further results in:

Q=P×t

[0050] In this case, P designates the power loss and t designates the time. This results in:

M×cp×δT=P×=t/P=frictional torque×rotational speed=2×π/60

[0051] The power loss or the frictional torque plotted over temperature is a known variable which can be placed and thus stored as a characteristic diagram in an algorithm, in the electronic computing device 22 designated as a control unit, particularly the storage device thereof. There are also frictional loss characteristic diagrams of drive units and the dependency thereof on temperature.

[0052] If this knowledge is linked to the use of predictive data, particularly route data, the predictive data enable the preliminary calculation of which average rotational speed and/or driving speed is set and thus also which power loss will prevail and which temperature change (δT) will result therefrom. Because the power losses in the gearbox 20 depend greatly on temperature, inter alia, due to the viscosity of the gearbox oil, the efficiency of the motor vehicle can be increased and also controlled and/or regulated in a targeted manner due to the knowledge of the predictive data.

[0053] Due to knowledge of the driving route, likely speed (city, country, highway), and the expected switch-off point of the motor vehicle (parking times) such as the duration of the expected stopped phase (parking time), for example, by means of constantly reoccurring events such as, for example, the daily drive to work with corresponding trip interruption, an algorithm can be weighted, in a targeted manner, as to when and which energy content of thermal energy is removed from the first circuit of the motor and transferred to the gearbox 20 in order to optimally operate the motor vehicle with respect to its overall efficiency. This thermal energy transfer can take place via the gearbox oil heat exchanger, which is already being used, for example. Thus, it can be calculated as a function of the driving time and/or the average driving speed and as a function of a predicted parking time whether or when it is expedient to transfer thermal energy from the motor to the gearbox 20.

[0054] Moreover, a need-based lowering of the gearbox temperature can occur with corresponding pending high-load cases. In corresponding load cases such as, for example, highway driving, a strong acceleration, a mountain drive with trailer, additional heat can be supplied to the gearbox 20 in the form of power loss due to the existing inner load-dependent losses. This leads to a temperature increase in the gearbox 20. In order to fulfill the temperature profile of the gearbox oil, the temperature must remain under a certain temperature limit which is also designated as a limit or limit value. This limit, for example, is 100° C. with respect to the temperature of the gearbox oil. If the gearbox temperature comes close to this limit, for example, attempts are made to cool down the gearbox 20 via the gearbox oil cooler by means of the first medium. The cooling need is reduced accordingly via the gearbox oil cooler once the temperature drops below the limit characterized as the temperature threshold and corresponding hysteresis. This can take place by increasing the temperature of the first medium and/or by changing the coolant volumetric flow on the gearbox oil cooler (switching valve).

[0055] By calculating the stopped time (parking time and/or probability of the parking time from learned utilization behavior), it is likewise expedient to increase the gearbox temperature in a targeted manner significantly before parking the motor vehicle in order to thereby use the stored enthalpy. Thus, an increased restart temperature of the gearbox 20 and the flange-mounted motor is achieved over the stopped time. This, in turn, leads to lower frictional power of the gearbox 20 and motor.

[0056] For example, gearbox oil heating is released starting at a certain coolant temperature of the motor. The gearbox oil is then heated until an especially advantageous temperature of the second medium and/or in the gearbox, also designated as the preferred temperature, is set, or there is cooling of the gearbox 20 based on a prevailing temperature level. In contrast, it is advantageous, however, to react predictably by means of the predictive data and to calculate an energetic thermal optimum by means of the predictive data as a strategy, according to which, for example, the powertrain 10 is operated.