Method for controlling temperature of electric drive unit of motor vehicle, in particular of motor vehicle

Abstract

The invention relates to a method for controlling the temperature of an electric drive unit of a motor vehicle having at least one electric motor (5), in which method a temperature control medium is fed through a flow path (14) by means of a pump (15) and at least one partial region (I) of the drive unit is controlled by means of the temperature control medium, the pump (15) can be operated at different operating points with different volumetric flows of the temperature control medium. A heat exchanger (20) is arranged in the flow path (14). A respective associated cooling value is calculated for the respective operating point, which cooling value characterizes the respective temperature of the local region (I), which temperature can be caused by the respective operating point of the pump (15) associated with the respective cooling value. One of the operating points is selected as a function of the calculated cooling value, and the pump (15) is operated at the selected operating point.

Description

Technical Field

[0001] The invention relates to a method for temperature control, ie cooling and / or heating, of an electric drive unit of a motor vehicle, in particular a car. Background Art

[0002] US2011 / 0214627A1 discloses a control device for an engine cooling system, in which an electric pump is controlled so as to circulate a coolant. In addition, CN102815222B discloses a thermal management system for a vehicle. Summary of the invention

[0003] The object of the present invention is to provide a method by means of which an electric drive unit of a motor vehicle, in particular a car, can be temperature-controlled, ie cooled and / or heated, particularly effectively and efficiently.

[0004] This object is achieved according to the invention by a method having the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0005] The invention relates to a method for temperature control, i.e. cooling and / or heating, of an electric drive unit of a motor vehicle, also referred to as a vehicle and preferably designed as a car, in particular a passenger car, having at least one electric motor. This means that the motor vehicle has an electric drive unit (also referred to as a drive device) and therefore has at least one electric motor, by means of which the motor vehicle can be driven electrically, in particular purely electrically. In particular, it is conceivable that in the method the electric motor drives the motor vehicle electrically, in particular purely electrically. Preferably, the electric motor is a high-voltage component, whose voltage, in particular the electrical operating voltage and the rated voltage are preferably greater than 50 volts, in particular greater than 60 volts and very preferably several hundred volts.

[0006] In the method, a temperature control medium is conveyed through a flow path by means of a pump. For this purpose, a pump is operated. The pump is in particular an electric pump, i.e. an electrically driven pump. At least one partial region of a drive unit, in particular an electric motor, is temperature controlled, i.e. heated and / or cooled, by means of the temperature control medium. If the temperature control medium has a higher temperature than the partial region, the temperature control medium is or serves as a heating medium, by means of which at least the partial region of the drive unit is heated, in particular by heat transfer from the temperature control medium to the partial region. If, for example, the temperature control medium has a lower temperature than the partial region, the temperature control medium is or serves as a coolant, by means of which at least the partial region is cooled, so that heat transfer from the partial region to the temperature control medium is achieved.

[0007] The local area of ​​the drive unit may be or include an electric motor. In other words, the local area may be at least a part of the electric motor or include at least a part of the electric motor. For example, the local area may be or include at least a part or a local area of ​​the stator and / or rotor (especially the rotor shaft) of the electric motor. The electric motor is also referred to as an electric motor or an electric motor. Alternatively or additionally, the local area may, for example, include at least a part or a local area of ​​a component of the drive unit that is attached to the electric motor, especially different from the electric motor, or alternatively or additionally, the local area may, for example, be at least a part or a local area of ​​a component of the drive unit that is attached to the electric motor, especially different from the electric motor. The component may, for example, have or include at least one inverter and / or a transmission.

[0008] The pump can be operated at different working points with different volume flow rates of the temperature control medium. In other words, the pump is configured to operate at different volume flow rates in the different working points. In other words, the pump can be operated at different working points, which are different from each other in terms of their respective temperature control medium volume flow rates, which are caused by the pump or by the temperature control medium caused by the pump or caused by the delivery that can be caused. This can be understood as follows: if the pump is operated in the first working point, the pump conveys the temperature control medium so that the temperature control medium has a first volume flow rate, that is, flows through the flow path with a first volume flow rate. If, for example, the pump is operated in the second working point, the pump conveys the temperature control medium so that the temperature control medium has a second volume flow rate different from the first volume flow rate, that is, flows through the flow path with a second volume flow rate different from the first volume flow rate. The corresponding volume flow rate corresponds to the corresponding mass flow rate of the temperature control medium, especially in the following manner, that is, the corresponding mass flow rate is obtained by multiplying the corresponding volume flow rate by the density of the temperature control medium. Therefore, the corresponding volume flow rate can be understood as the corresponding mass flow rate of the temperature control medium or the corresponding volume flow rate can be equivalent to the corresponding mass flow rate of the temperature control medium.

[0009] In the method, a heat exchanger is arranged in the flow path, which is arranged upstream of the partial region, in particular upstream of the motor, in the flow direction of a temperature control medium that is pumped by the pump and thus flows through the flow path and thus through the heat exchanger. In particular, the heat exchanger is arranged in the flow path downstream of the pump. In the method, the temperature control medium that is pumped by the pump and thus flows through the flow path and in particular another fluid that is different from the temperature control medium flows through the heat exchanger. In particular, the temperature control medium is a first fluid and the other fluid is in particular a second fluid that is different from the first fluid.

[0010] The heat exchanger exchanges heat between the temperature control medium and the fluid, thereby, in particular, the temperature control medium is temperature-controlled upstream of the local area of ​​the drive unit, i.e., cooled and / or heated. In other words, due to the heat exchange between the temperature control medium and the fluid by the heat exchanger, the temperature control medium is temperature-controlled on its way through the flow path and thus from the pump to the local area of ​​the drive unit. When the temperature control medium and the other fluid flow through the heat exchanger, for example, if the other fluid has a higher temperature than the temperature control medium, heat is transferred from the other fluid to the temperature control medium by the heat exchanger, thereby heating the temperature control medium. When the temperature control medium and the other fluid flow through the heat exchanger, for example, if the other fluid has a lower temperature than the temperature control medium, heat is transferred from the temperature control medium to the other fluid by the heat exchanger, thereby cooling the temperature control medium. Thus, for example, the local area can be heated by means of the temperature control medium heated by the heat exchanger. It is also conceivable to cool the local area of ​​the drive unit by means of the temperature control medium cooled by the heat exchanger.

[0011] Now, in order to be able to particularly effectively and particularly efficiently temperature-control a local area of ​​the drive unit, in the method, at least one correspondingly belonging, that is, a cooling value belonging to the corresponding operating point is calculated for the corresponding operating point of the pump by means of an electronic computing device, in particular according to a computing model (also called a temperature model). The corresponding cooling value characterizes the corresponding temperature, in particular the temperature change and thus the temperature control of the local area of ​​the drive unit, which can be caused by the corresponding operating point of the pump belonging to the corresponding cooling value. In other words, by the operation of the pump (in particular theoretically) in the corresponding operating point, the corresponding temperature, in particular the temperature change of the local area of ​​the drive unit can be achieved, because if the pump is operated in the corresponding operating point, the pump (will) convey the temperature control medium to the local area and in particular convey through the local area. Thus, in the corresponding operating point, the local area of ​​the drive unit (will) be temperature-controlled, that is, cooled or heated by means of the temperature control medium, which (will) lead to the corresponding temperature, in particular the temperature change of the local area or the drive unit or this (will) be accompanied by or equal to or correspond to the temperature or temperature change of the local area. Therefore, in particular, it is provided in the method that the temperature control medium is conveyed through the flow path and thus to the local area by means of a pump, and it is particularly provided that the temperature control medium is conveyed through the local area by means of a pump. Therefore, heat exchange can be carried out between the temperature control medium flowing through the local area and the local area, thereby at least the local area of ​​the drive unit is temperature controlled. When the temperature control medium flows through the local area, if, for example, the temperature control medium has a lower temperature than the local area, the temperature of the local area can be kept low, so that the local area can be protected from undesirable heating, and the temperature change of the local area in this case is cooling of the local area. When the temperature control medium flows through the local area, if, for example, the temperature control medium has a higher temperature than the local area, the temperature of the local area can be kept high, so that undesirable cooling or undesirable low temperature of the local area can be avoided, and the temperature change in this case is heating of the local area. Therefore, the local area can be kept at a favorable temperature or in a favorable temperature range by means of the temperature control medium, so that a particularly efficient operation of the drive unit, in particular the motor, can be achieved. A “temperature change of a local area” is to be understood in particular as a difference or differential between a first temperature and a second temperature of a local area, for example a local area of ​​a drive unit has a first temperature at a first time and / or a first operating point and a second temperature at a second time and / or a second operating point, so that for example a temperature change is caused by a change in the operating point of a pump, i.e. as a result of which the pump is first operated at a first operating point and then at a second operating point or vice versa. In particular, a “temperature change” is to be understood as the degree or intensity of temperature control of a local area which is or can be caused by the respective operating point or by a temperature control medium.

[0012] In the method according to the invention, one of the operating points is selected according to the calculated cooling value by means of an electronic calculation device, and the pump is operated, in particular regulated, in the selected operating point by means of the electronic calculation device. For example, one of the calculated cooling values ​​is selected and the pump is operated in the operating point belonging to the selected cooling value by means of the electronic calculation device. It can be seen that the calculation of the cooling value is a precalculation, the purpose of which is to select one of the operating points after the precalculation and therefore based on the precalculation and to operate the pump in the selected operating point. As a result, it is possible to avoid changing the operating point of the pump too frequently, so that effective temperature control can be achieved in a particularly efficient manner.

[0013] For example, the flow path is a component of a circuit through which a temperature control medium can flow, in which a heat exchanger, a pump and at least a partial area of ​​a drive unit, in particular at least one partial area of ​​an electric motor, are also arranged. A tank or container can also be arranged in the circuit in which the temperature control medium is or can be accommodated.

[0014] In order to be able to particularly effectively and particularly efficiently temperature control the local area and thus the drive unit, in one embodiment of the present invention, it is provided that an objective function of an optimization problem is created according to the cooling value by means of an electronic computing device, and the objective function of the optimization problem includes the rotation speed of the pump in the working point as a parameter or variable of the objective function. At least one or preferably exactly one extreme value of the objective function is determined, especially calculated, by means of the electronic computing device, and the working point belonging to the determined extreme value is selected by means of the electronic computing device. Thus, on the one hand, the local area can be particularly effectively, that is, especially strongly, temperature controlled, and on the other hand, the pump can be operated as efficiently as possible, especially energy-saving. "The rotation speed of the pump" should be understood in particular as follows: the pump, for example, has a pump housing and a conveying element arranged in the pump housing. In addition, the pump, for example, has a drive, especially an electric motor. The conveying element can be driven in particular by means of a drive and can thus rotate relative to the pump housing around an axis of rotation. By rotating the conveying element relative to the pump housing around the axis of rotation, that is, by driving the conveying element, the conveying element and the pump can be used to convey the temperature control medium. For example, in the first working point, the conveying element rotates at a first speed relative to the pump housing around the axis of rotation, thereby, for example, generating a first volume flow of the temperature control medium. In the second operating point, for example, the conveying element rotates at a second speed relative to the pump housing around the axis of rotation, and the second speed is different from the first speed. This, for example, generates a second volume flow of the temperature-control medium. Therefore, the different volume flows in different operating points are caused by the different speeds of the conveying element (i.e., the pump). The background related to this is, in particular, that as the speed of the pump increases, the losses of the pump also increase. Therefore, it is desirable to keep the speed of the pump as low as possible. Other elements in the drive unit (also referred to as the transmission or drive device) will also increase their losses due to the increase in oil flow, which includes, for example, shear losses in the gap of the electric motor and oil stirring losses of the transmission. On the other hand, for example, the higher the volume flow of the temperature-control medium flowing through a local area, the stronger the temperature control (i.e., stronger cooling or stronger heating) will be, and the higher the speed of the pump, the greater the volume flow of the temperature-control medium. "Determining, in particular calculating the extreme value of the objective function" should be understood as minimizing or maximizing the objective function with the aid of an electronic computing device. This allows the optimum value of the target function to be determined with regard to the temperature control of the subregion, ie the optimum temperature control of the subregion, so that in particular the rotational speed of the pump can be kept as low as possible and the subregion of the drive unit can be temperature controlled as strongly as possible.

[0015] It has proven to be particularly advantageous if the target function is the temperature change of the local area that can be brought about by the operating point, the extreme value being the optimum value resulting from the minimum possible rotational speed of the pump and the maximum possible temperature change of the local area. Thus, it is possible to achieve the strongest possible temperature control, in particular cooling, of the local area and to keep the rotational speed of the pump as low as possible, so that on the one hand a particularly effective temperature control of the drive unit can be achieved and on the other hand the most efficient possible operation of the pump and thus of the entire motor vehicle can be achieved.

[0016] For example, at least one corresponding temperature value is calculated for the corresponding operating point by means of an electronic calculation device, in particular based on a calculation model, which temperature value characterizes the corresponding supply temperature (also called outlet temperature or designed as outlet temperature), at which the temperature control fluid is provided by the heat exchanger at the corresponding operating point, and the temperature control fluid flows out of the heat exchanger, in particular, for example, via an outlet of the heat exchanger, and the corresponding cooling value belonging to the corresponding operating point is calculated by means of the electronic calculation device from the temperature value belonging to the corresponding operating point. As a result, the cooling value can be determined particularly accurately, so that on the one hand the motor can be effectively cooled and on the other hand the pump can be operated particularly efficiently.

[0017] In order to be able to control the temperature of the drive unit particularly effectively, it is provided in another embodiment of the invention that the electric machine comprises the rotor with the rotor shaft. For example, the electric machine also comprises the stator, by means of which the rotor can be driven and thus can rotate relative to the stator about the motor rotation axis. By driving the rotor, the rotor shaft can rotate relative to the stator about the motor rotation axis. In particular, the electric machine can provide a drive torque via its rotor for driving the motor vehicle, in particular purely electrically.

[0018] In order to achieve particularly effective temperature control of the drive unit, in particular the electric motor, it has proven to be particularly advantageous to use at least one length region of the rotor shaft as a partial region. In particular, it is conceivable that the pump, by conveying the temperature control medium, conveys the temperature control medium through the partial region and thus the length region, in particular the entire rotor shaft, whereby the electric motor can be effectively temperature controlled.

[0019] Another embodiment is characterized in that, by means of an electronic computing device, in particular according to a calculation model, at least one corresponding second cooling value is calculated for a corresponding operating point, and the second cooling value characterizes a corresponding temperature change of a second local area of ​​a drive unit, in particular a motor, which temperature change can be caused by a corresponding operating point of the pump belonging to the corresponding second cooling value. The description of the first local area above and below can also be simply transferred to the second local area and vice versa. By means of an electronic computing device, one of the operating points is selected according to the calculated first cooling value and the calculated second cooling value and the pump is operated in the selected operating point by means of the electronic computing device. The background of this embodiment is that the drive unit, in particular the motor, is divided into each local area and the corresponding temperature control of the corresponding local area is determined, that is, the temperature change, which can be caused by the temperature control medium and thus the corresponding operating point. Thus, for example, the drive unit can be advantageously temperature-controlled not only in the first local area but also in the second local area, so that effective temperature control of the drive unit can be achieved.

[0020] It has been found to be particularly advantageous here if a first length region of the rotor shaft is used as the first partial region and a second length region of the rotor shaft is used as the second partial region. As a result, the drive unit, in particular the electric motor, can be temperature-controlled particularly advantageously.

[0021] For example, by conveying a temperature control medium, the temperature control medium is conveyed through the first subregion and the second subregion, so that a particularly advantageous heat exchange between the temperature control medium and the subregions can be achieved.

[0022] In a further particularly advantageous embodiment of the invention, a liquid, in particular oil, is used as the temperature control medium, as a result of which the drive unit can be temperature-controlled in a particularly advantageous manner.

[0023] Finally, in order to achieve particularly advantageous temperature control of the temperature control medium, it is particularly advantageous to use a liquid as the further fluid. For example, the liquid is at least partially, in particular at least mostly, water or comprises water, so that a particularly advantageous heat exchange can be achieved between the temperature control medium and the further fluid.

[0024] In particular, it is conceivable that the pump (for example, configured as an oil pump) and thus the circuit (for example, configured as an oil circuit) can be controlled or regulated at least almost freely by means of an electronic computing device. The volume flow of the temperature control medium and thus the amount of temperature control medium (also referred to as flow or oil flow) delivered by means of the pump and flowing through the flow path and, in particular, the circuit is approximately equivalent to the rotational speed of the pump (also referred to as pump rotational speed). In particular, for example, the pump, in particular its drive, can be regulated or controlled by means of an electronic computing device (also referred to as a controller or configured as a controller). For example, the electronic computing device includes a thermal model (calculation model), which is stored, for example, in an especially electrical or electronic memory, in particular a data memory, of the electronic computing device. For example, at least one or more temperature sensors are provided, and the corresponding temperature of the temperature control medium is detected or can be detected by means of the corresponding temperature sensors. Alternatively or additionally, the corresponding temperature can be modeled, that is, calculated by means of the calculation model. The corresponding temperature of the temperature control medium is used, for example, as an input parameter in the thermal model, so that, for example, the electronic computing device calculates the corresponding cooling value and / or the corresponding temperature value according to the corresponding detected temperature of the temperature control medium by means of the thermal model.

[0025] It is usually provided that the electronic computing device calculates the amount of the temperature-control medium to be delivered by means of the pump by means of a calculation model and according to the temperature of the temperature-control medium detected accordingly and, for example, according to at least one or more other model parameters and controls the pump according to the calculated amount of the temperature-control medium to be delivered by means of the pump and thereby, for example, sets the speed of the pump so that the pump delivers, i.e. supplies the calculated amount of the temperature-control medium. For example, if the temperature of the local area (especially the motor and the rotor in particular) rises now, the pump is controlled in this way, especially mostly from a certain extreme temperature, so that the speed of the pump and thus the amount of the temperature-control medium or its volume flow increase, so that the local area can then output heat to the temperature-control medium. The rotor shaft can be constructed similarly to a pipe or regarded as a pipe, for example, the temperature-control medium is delivered to the rotor shaft via an inlet and delivered out of the rotor shaft via an outlet by a pump. Therefore, the temperature-control medium can flow into the rotor shaft via an inlet and flow out of the rotor shaft via an outlet. For example, the inlet is arranged on the first axial end face of the rotor shaft. For example, the outlet is arranged on the second axial end face of the rotor shaft, and the second axial end face of the rotor shaft is away from the first axial end face along the axial direction of the rotor shaft. It is also conceivable that the temperature control medium flows into the rotor shaft in the axial direction of the rotor shaft or in the radial direction of the rotor shaft and / or the temperature control medium can flow out of the rotor shaft in the axial direction of the rotor shaft or in the radial direction of the rotor shaft. Based on a possible temperature difference between the temperature control medium and the rotor shaft or the local area, a heat exchange occurs between the temperature control medium flowing through the local area and the local area, whereby the local area is temperature-controlled, i.e., cooled or heated. The temperature difference is also referred to as dT. The heat exchange between the temperature control medium flowing through the local area and the local area (rotor shaft) is carried out, for example, according to the principle of forced convection, in particular.

[0026] The following description relates in particular to the cooling of a local area by means of a temperature control medium: when the temperature control medium is provided for cooling the local area (i.e. is designed or used as a coolant), the higher the speed (also referred to as flow rate) at which the temperature control medium flows through the local area, the more heat the temperature control medium can absorb from the local area, in particular per unit of time. In this case, it is provided, for example, that the temperature control medium is cooled by means of a heat exchanger. However, when the local area is to be cooled or cooled by means of a temperature control medium, the outlet temperature of the temperature control medium flowing out of the local area at a higher speed of the temperature control medium is lower than the outlet temperature when the temperature control medium flows through the local area at a relatively lower speed. For example, assuming that the speed of the temperature control medium flowing through the local area is constant and assuming that the inlet temperature of the temperature control medium when it flows into the local area is constant (the temperature control medium flows into the local area at this inlet temperature), the heat exchange between the temperature control medium flowing through the local area and the local area is carried out according to the speed of the temperature control medium flowing through the local area and according to the exchange surface (through which the heat exchange between the temperature control medium flowing through the local area and the local area can be achieved). The lower the speed at which the temperature control medium flows through the local area, the higher the outlet temperature of the temperature control medium flowing out of the local area (the greater the temperature difference between the inlet temperature and the outlet temperature of the temperature control medium when it flows into the local area). The higher the speed (also called flow velocity) at which the temperature control medium flows through the local area, the higher the outlet velocity at which the temperature control medium flows out of the local area. The higher the speed at which the temperature control medium flows through the local area, the lower the outlet temperature at which the temperature control medium flows out of the local area (the smaller the temperature difference between the outlet temperature and the inlet temperature).

[0027] The problem with conventional solutions is that when or as the temperature control demand, in particular cooling demand, of a local area, in particular of an electric machine, increases, the pump is operated, in particular the pump is adjusted, so that a high or higher volume flow is generated in the flow path and in particular in the circuit and in the local area, whereby the local area can advantageously output heat to the temperature control medium or absorb heat in the temperature control medium. The high flow rate of the temperature control medium, for example, assuming a constant temperature in the container, results in a small temperature difference between the heat exchanger inlet temperature at which the temperature control medium flows into the heat exchanger and the heat exchanger outlet temperature at which the temperature control medium flows out of the heat exchanger. In particular, if the temperature control medium is or comprises oil or the other fluid is or comprises water, the heat exchanger is a so-called oil-water heat exchanger. A small temperature difference between the heat exchanger inlet temperature and the heat exchanger outlet temperature leads to a relatively high temperature of the temperature control medium flowing into the local area, in particular into the rotor shaft, which leads to a relatively low temperature control power, in particular a low cooling power, in the local area, compared to a lower heat exchanger outlet temperature or to a larger difference between the heat exchanger outlet temperature and the heat exchanger inlet temperature. In other words, the higher the speed at which the temperature control medium flows through the local area, the more heat is removed from the local area by means of the temperature control medium per time unit (when cooling the local area) or the more heat is transferred to the local area by means of the temperature control medium per time unit (when heating the local area), but the higher the speed at which the temperature control medium flows through the local area and thus through the flow path and the heat exchanger, the higher the heat exchanger outlet temperature of the temperature control medium, the temperature control medium flows out of the heat exchanger, for example, at the heat exchanger outlet temperature (when the temperature control medium is cooled by the heat exchanger), for example, the temperature control medium flows into the local area at the heat exchanger outlet temperature. In other words, the higher the heat exchanger outlet temperature (temperature at which the temperature-control medium flows out of the heat exchanger), the higher the temperature, such as the above-mentioned inlet temperature, the temperature of the temperature-control medium when it flows into the local area. Therefore, there is a conflict of objectives between the desire to convey the temperature-control medium through the flow path and thus through the heat exchanger and the local area at a smaller volume flow rate or at a lower speed to achieve a lower heat exchanger outlet temperature and the desire to convey the temperature-control medium through the local area at a larger volume flow rate or at a higher speed so as to remove high heat from the local area per time unit or to input high heat into the local area. Therefore, there is a conflict of objectives between the desire to operate the pump at a low speed and the desire to operate the pump at a high speed, because a high volume flow rate or high speed of the temperature-control medium can be generated by the high speed of the pump and a low volume flow rate or low speed of the temperature-control medium can be generated by a relatively low or low speed of the pump. In particular, it is desired that the speed at which the temperature-control medium flows through the heat exchanger is low, because in this case the temperature-control medium can be strongly temperature-controlled, especially cooled, by means of the other fluid on its path through the heat exchanger.

[0028] The above-mentioned conflict of objectives can now be resolved by the method according to the invention. The method according to the invention enables an optimal combination of the greatest possible or strongest possible temperature control (in particular cooling) of the local area and the smallest possible or lowest possible rotational speed of the pump, i.e. the smallest possible or lowest possible speed of the temperature control medium. Thus, for example, for cooling the local area, a temperature control medium with a particularly advantageous low heat exchanger outlet temperature can be provided by the heat exchanger, so that the temperature control medium can then flow into the local area at an advantageous low temperature, and on the other hand, the temperature control medium can be advantageously conveyed quickly, i.e. at an advantageously high speed, through the local area, so that, for example, when cooling the local area or for cooling the local area, a large amount of heat can be transported away from the local area per unit of time by the cooling medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further details of the present invention are obtained from the following description of preferred embodiments together with the accompanying drawings. The accompanying drawings are as follows:

[0030] Figure 1 A schematic diagram showing an electric machine of a motor vehicle drive unit, which is temperature-controlled, ie cooled or heated; and

[0031] Figure 2 A schematic longitudinal section through a rotor shaft of an electric machine is shown. DETAILED DESCRIPTION

[0032] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0033] According to the following Figure 1 and Figure 2 A method for temperature control, i.e. cooling and / or heating, of at least a partial region of an electric drive unit of a motor vehicle (also referred to as a vehicle) is described. The drive unit has at least one electric motor 1. The motor vehicle can be driven by means of the electric motor 1, in particular purely electrically. It is conceivable that in the method the motor vehicle is driven by means of the electric motor 1, in particular purely electrically. The electric motor 1 has a stator 2 and a rotor 3, which can be driven by means of the stator 2 and can thus rotate relative to the stator 2 about a motor rotation axis 4. The rotor 3 has a rotor shaft 5, which can be driven by the described drive of the rotor 3 and can thus rotate relative to the stator 2 about a motor rotation axis 4. The electric motor 1 can provide a drive torque via its rotor shaft 5 for driving the motor vehicle, in particular purely electrically.

[0034] The local area of ​​the drive unit to be temperature-controlled is or includes at least a part or a local area of ​​the motor 1, so that in the method the motor 1, i.e. at least a local area of ​​the motor, is temperature-controlled. In the method, the motor 1 is temperature-controlled by means of a temperature control device 6. The temperature control device 6 comprises a circuit 7, through which a temperature control medium can flow. In particular, it is provided that in the method the temperature control medium flows through the circuit 7. In the embodiment shown in the figure, the temperature control medium is a liquid, in particular oil, so that when oil is mentioned hereinafter, the oil is to be understood as the temperature control medium. The method is explained hereinafter based on the temperature control of the motor 1 achieved by cooling, so that in the method according to the embodiment shown in the figure, the motor 1 is cooled by means of oil. In particular, in the method, at least the rotor shaft 5 of the motor 1 is cooled by means of oil, which is, for example, due to the fact that the motor 1 is cooled by means of oil. Figure 2 The rotor shaft 5 has in its interior a particularly central temperature control channel 8 which is currently designed as a cooling channel or serves as a cooling channel and which is also referred to simply as a channel and through which a temperature control medium flows or can flow. Thus, for example, the channel and therefore the rotor shaft 5 are arranged in a circuit. Figure 2 In the figure, arrows 9, 10 and 11 indicate a temperature control medium flowing through the flow circuit 7 and thus the rotor shaft 5, by means of which the rotor shaft 5 is temperature controlled, in the present case cooled. In particular, arrow 9 indicates that the temperature control medium flows into the channel and thus the rotor shaft 5, for example, at an inlet temperature (also referred to as the shaft inlet temperature), in particular via the channel or the inlet of the rotor shaft 5. Arrow 11, for example, indicates that the temperature control medium flows out of the rotor shaft 5 or from the channel, in particular at an outlet temperature (also referred to as the shaft outlet temperature), in particular via the outlet of the channel or the rotor shaft 5. Arrow 11 indicates that the temperature control medium flows through the channel and thus the rotor shaft 5, in particular from the inlet to the outlet. In the case of cooling the rotor shaft 5 described above, the temperature control medium heats up on its path through the channel from the inlet to the outlet, so that when cooling the rotor shaft 5 (also referred to as the cooling case), the shaft outlet temperature is higher than the shaft inlet temperature, so that the temperature control medium heats up on its path through the channel from the inlet to the outlet. The rotor shaft 5 is thereby cooled. The difference (also called difference, temperature difference or temperature difference) between the shaft outlet temperature and the shaft inlet temperature of the temperature control medium characterizes, for example, the intensity, magnitude or degree of the temperature control of the rotor shaft 5, which is realized in the exemplary embodiment shown in the figures in the form of cooling of the rotor shaft 5 and thus of the electric machine 1. In particular, for example, the difference between the shaft outlet temperature and the shaft inlet temperature characterizes or describes the temperature change of the rotor shaft 5 caused by the cooling of the rotor shaft 5 and thus the temperature control medium flowing through the rotor shaft 5, which temperature change is a temperature reduction of the rotor shaft 5, since the rotor shaft 5 is cooled in the exemplary embodiment shown in the figures.

[0035] exist Figure 2, the length regions of the rotor shaft 5 are represented by I, II and III. It can be seen that the length regions I and III are partial regions of the rotor shaft 5 and thus the motor 1, and the length regions I, II and III are connected along the axial direction of the rotor shaft 5, that is, they are continuously arranged, and the axial direction of the rotor shaft 5 coincides with the motor rotation axis 4. For example, the above-mentioned partial region of the motor 1 is the length region I, and the length regions II and III are other partial regions of the motor 1.

[0036] Depend on Figure 1 It can be seen that the channel (temperature control channel 8) and thus the rotor shaft 5 and the motor 1 are arranged in the circuit 7. Since the rotor shaft 5 is cooled in the embodiment shown in the figure, the circuit 7 is a cooling circuit or the circuit 7 is used as a cooling circuit or works as a cooling circuit. The circuit 7 includes an inlet line 12 and a return line 13. A tank 19 (also called a container) is also arranged in the circuit 7. The oil, which is currently in the form of oil and used as a coolant, can be at least temporarily accommodated, that is, stored in the tank 19, especially when a transmission or an oil sump (also called a sump) is formed. The oil can be guided from the tank 19 to the rotor shaft 5 and the channel (temperature control channel 8) through the inlet line 12. Therefore, the oil can flow out from the temperature control channel 8 via the outlet and then flow into the return line 13 and return to the tank 19 through the return line 13. The oil flowing through the inlet line 12 can flow out from the inlet line 12 and then flow through the inlet and thus flow into the channel via the inlet and then flow through the channel and flow from the inlet to the outlet. A part of the inlet line 12 is a flow path 14 through which the oil flows or through which the oil can flow. Here, the oil flows through the flow path 14 on its way from the tank 19 to the channel.

[0037] The temperature control medium 6 further comprises a pump 15 arranged in the circuit 7, in particular in the feed line 12, by means of which oil is conveyed through the circuit 7 and thus through the temperature control channel 8, the feed line 12 and the return line 13 in the method. Since the temperature control medium is oil in the exemplary embodiment shown in the figures, the pump 15 is also referred to as an oil pump. In the exemplary embodiment shown in the figures, the pump 15 is designed as an electric pump. The pump 15 has a Figure 1 1 and the pump housing 17 are particularly schematically shown in the drawing. The pump 15 also has a drive 18, which is designed in the present case as an electric motor and is also referred to as a motor, by means of which the delivery element 16 can be driven and thus rotated or rotatable about an axis of rotation relative to the pump housing 17. By rotating the delivery element 16, the oil is conveyed by means of the delivery element 16 and thus the pump 15, more precisely through the circuit 7.

[0038] The pump 15 can be operated in different operating points which differ from one another in terms of the respective rotational speeds at which the conveying element 16 is rotated about the rotational axis relative to the pump housing 17 by means of the drive 18. In other words, the conveying element 16 can be rotated about the rotational axis relative to the pump housing 17 at different rotational speeds by means of the drive 18. This means, for example, that in a first operating point, the drive 18 drives the conveying element 16 in such a way that the conveying element 16 rotates about the rotational axis relative to the pump housing 17 at a first rotational speed, so that in the first operating point the conveying element 16 rotates about the rotational axis relative to the pump housing 17 at the first rotational speed or in the first operating point the conveying element 16 has a first rotational speed. In a second operating point, for example, the drive 18 drives the conveying element 16 in such a way that the conveying element 16 rotates about the rotational axis relative to the pump housing 17 at a second rotational speed. Therefore, in the second operating point, the conveying element 16 rotates about the rotational axis relative to the pump housing 17 at the second rotational speed or in the second operating point, the conveying element 16 has a second rotational speed. In this case, the first rotational speed and the second rotational speed differ from one another, so that, for example, the second rotational speed is greater or less than the first rotational speed. The corresponding rotational speed of the conveying element 16 causes a corresponding volume flow of the oil, with which the oil flows through the circuit 7 and thus the temperature control channel 8, i.e. the rotor shaft 5. This means, for example, that in the first operating point, the oil flows through the circuit 7 and thus the temperature control channel 8 with a first volume flow, and in the second operating point, the oil flows through the circuit 7 and thus the temperature control channel 8 with a second volume flow, and the first volume flow and the second volume flow are different from each other. In other words, the second volume flow is greater than or less than the first volume flow. In other words, the first volume flow of the oil in the first operating point and the second volume flow of the oil in the second operating point, which is different from the first volume flow, flows through the circuit 7 and thus the temperature control channel 8. Here, the greater the rotational speed of the conveying element 16, the greater the volume flow of the oil. Therefore, if, for example, the second rotational speed is greater than the first rotational speed, the second volume flow of the oil caused by the second rotational speed is greater than the first volume flow of the oil caused by the first rotational speed. It can be seen that the pump 15 can therefore be operated at different volume flows of the oil at different operating points.

[0039] The temperature control device 6 further comprises a heat exchanger 20 which is arranged in the flow path 14 upstream of the motor 1, in particular upstream of the rotor shaft 5 and completely in particular upstream of the temperature control channel 8 and downstream of the pump 15, and through which the oil can flow. This means that the oil flows through the heat exchanger 20 on its way from the pump 15 to the rotor shaft 5, i.e. to the temperature control channel 8, through the flow path 14. The heat exchanger 20 is further arranged Figure 1In the fluid circuit 21, which is particularly schematically shown in the figure and is provided in addition to the circuit 7, another fluid can flow through or flow through the fluid circuit. Oil is a first liquid and the fluid is preferably a second liquid. For example, the other fluid is or includes water at least partially, in particular at least mostly. Since the heat exchanger 20 is not only provided in the circuit 7 but also in the fluid circuit 21, the heat exchanger 20 can be flowed through by both the oil and the other fluid. In particular, it is provided in the method that not only the oil but also the other fluid flows through the heat exchanger 20. Heat can be exchanged between the oil flowing through the heat exchanger 20 and the other fluid flowing through the heat exchanger 20 by the heat exchanger 20, so that the oil flowing through the heat exchanger 20 can be temperature-controlled, that is, cooled or heated, in particular temperature-controlled by the heat exchanger 20 with the help of the other fluid flowing through the heat exchanger 20. Since the rotor shaft 5 is cooled by means of oil in the embodiment shown in the figure, the oil flowing through the heat exchanger 20 is cooled by means of the other fluid flowing through the heat exchanger 20 in the embodiment shown in the figure. This is achieved in that heat is transferred from the oil flowing through the heat exchanger 20 via the heat exchanger 20 to the other fluid flowing through the heat exchanger 20. Since the oil and the other fluid are each a liquid, wherein the second fluid is preferably water or comprises water, the heat exchanger 20 is also referred to as an oil-water heat exchanger (ÖWWT). After the oil flows through the temperature control channel 8 and thus controls the temperature of the rotor shaft 5 (in the present case, cools it), the oil returns from the temperature control channel 8 and thus from the rotor shaft 5 to the tank 19 via the return line 13.

[0040] The temperature control device 6 comprises a first sensor 22, which is configured as a first temperature sensor. The temperature of the oil flowing through the flow path 14 is detected by means of the sensor 22, especially downstream of the heat exchanger 20 and upstream of the temperature control channel 8 or the rotor shaft 5. The temperature detected by means of the sensor 22 is also called the first temperature. For example, the first temperature is the shaft inlet temperature. It can be seen that the oil has a first temperature in the circuit 7, especially the flow path 14, downstream of the heat exchanger 20 and upstream of the temperature control channel 8, for example. Alternatively or additionally, the temperature control device 6 has a second sensor 23, which is configured as a second temperature sensor, for example. The second temperature of the oil in the tank 19, for example, is detected by means of the sensor 23, so that the oil has the second temperature in the tank 19, for example. It is also conceivable that at least one of the temperatures is modeled, that is, calculated by means of a calculation model.

[0041] The temperature control device 6 also includes Figure 1, which is also referred to as a controller. In the method, the electronic computer 24 controls the pump 15, in particular the drive 18, thereby, for example, controlling or regulating the pump 15. In other words, the method provides that the pump 15, in particular the drive 18, is operated, i.e. controlled or regulated, by means of the controller. In particular, when operating the pump 15, it is provided that the controller sets or can set different operating points and thus different rotational speeds of the pump 15.

[0042] Now there is usually the following conflict of objectives: on the one hand, it is desired that the oil flows through the temperature control channel 8 and thus the rotor shaft 5 as quickly as possible and therefore with the highest possible volume flow rate, so that a large amount of heat can be transported away from the rotor shaft by means of the oil per time unit in order to cool the rotor shaft 5. On the other hand, it is desired that the oil flows through the heat exchanger 20 as slowly as possible and therefore with the smallest possible volume flow rate, so that the oil is cooled as strongly as possible by means of the heat exchanger 20. For example, the oil with the heat exchanger inlet temperature flows into the heat exchanger 20, especially via the inlet of the heat exchanger 20, and for example, the oil flows out of the heat exchanger 20 with the heat exchanger outlet temperature, especially via the outlet of the heat exchanger 20. For example, the first temperature of the oil is the heat exchanger outlet temperature, or the first temperature is generated by the heat exchanger outlet temperature. Therefore, for example, the oil has the heat exchanger inlet temperature upstream of the heat exchanger 20 and especially downstream of the pump 15, and for example, the oil has the heat exchanger outlet temperature downstream of the heat exchanger 20 and especially upstream of the temperature control channel 8, so that for example, the heat exchanger 20 provides oil with the heat exchanger outlet temperature. Therefore, the heat exchanger outlet temperature is also called the supply temperature. Since the oil is cooled by the heat exchanger 20 in the embodiment shown in the figure, the heat exchanger outlet temperature of the oil is lower than the heat exchanger inlet temperature of the oil. The difference between the heat exchanger outlet temperature and the heat exchanger inlet temperature of the oil (also called difference, temperature difference or temperature difference) is, characterizes or describes the intensity, scale or degree of oil temperature control caused or induced by the heat exchanger 20. Since the oil is cooled by the heat exchanger 20 in the embodiment shown in the figure, the oil temperature control caused or induced by the heat exchanger 20 is the cooling of the oil. The lower the heat exchanger outlet temperature or the smaller the difference between the heat exchanger outlet temperature and the heat exchanger inlet temperature, the stronger the oil is cooled by the heat exchanger 20. The greater the difference between the shaft outlet temperature and the shaft inlet temperature or the higher the shaft outlet temperature, the stronger the rotor shaft 5 is cooled by the oil. With regard to the cooling of the oil caused or caused by the heat exchanger 20, it is desirable that the oil flows through the heat exchanger 20 as slowly as possible, i.e., with the smallest possible volume flow, in order to thereby achieve the smallest possible heat exchanger outlet temperature or the largest possible difference between the heat exchanger outlet temperature and the heat exchanger inlet temperature of the oil. Therefore, the conflict of objectives is particularly that, on the one hand, the largest possible rotational speed of the delivery element 16 is sought in order to cause the largest possible volume flow of the oil through the rotor shaft 5, and on the other hand, the smallest possible rotational speed of the delivery element 16 is set in order to thereby cause or set the smallest possible volume flow of the oil through the heat exchanger 20. Another advantage of the smallest possible rotational speed of the delivery element 16 and therefore of the pump 15 is that as the rotational speed of the pump 15 increases, the losses of the pump 15 and other elements in the oil flow increase, so that the pump 15 losses can be advantageously kept small by the low rotational speed of the pump 15.

[0043] The above method can solve or cope with the conflict of objectives, so that the electric machine 1 can be particularly effectively and efficiently temperature-controlled, in the present case cooled, by means of the method. By means of the electronic computer 24, according to a calculation model (also called a thermal model and stored, for example, in a data memory of the electronic computer 24), at least one corresponding associated cooling value is calculated for the respective adjustable operating point of the pump 15, which cooling value characterizes, that is, describes or indicates the respective temperature of the rotor shaft 5, which temperature can be caused by the respective operating point of the pump 15 belonging to the respective cooling value. Since the rotor shaft 5 is divided into length regions I, II and III (also called sections) and is therefore viewed in length regions or sections, for example, by means of the electronic computer 24, according to the calculation model, for the respective operating point and the respective length region I, II, III, at least one corresponding associated cooling value is calculated, which cooling value characterizes the respective temperature of the respective length region I, II, III, which temperature can be caused by the respective operating point of the pump 15 belonging to the respective cooling value. Thus, for example, a first cooling value characterizes a first temperature of the first length region I, which can be caused, that is, set, by the operating point and thus the associated volume flow. Thus, for example, the second cooling value characterizes the second temperature of the second length region II, which can be caused, i.e. set, by the operating point of the pump 15 and thus the associated volume flow. Thus, for example, the third cooling value characterizes the third temperature of the third length region III, which can be set, i.e. caused, by the operating point of the pump 15 and thus the associated volume flow. The calculation of the cooling value is a precalculation, since the precalculation is performed before an operating point is set, i.e., the cooling value is calculated before, for example, the pump 15 is switched from one operating point to another. Preregulation or precontrol can thus be achieved.

[0044] One of the operating points is selected as a function of the calculated cooling value by means of the electronic computer 24. The pump 15 is then activated by means of the electronic computer 24, so that the pump 15 is operated at the selected operating point.

[0045] For example, the corresponding cooling value characterizes or describes the corresponding temperature change of the corresponding length region I, II, III, which can be caused by the corresponding operating point and thus the corresponding volume flow. Since the rotor shaft 5 is cooled in the embodiment shown in the figure, the temperature change involves a temperature reduction, that is, the cooling of the corresponding length region I, II, III. For example, an objective function of an optimization problem is created based on the cooling value by means of an electronic computing device 24, and the objective function of the optimization problem includes the rotation speed of the pump 15 belonging to the operating point as a parameter. This means that the rotation speed of the pump 15 is a parameter, that is, a variable of the objective function. At least or exactly one extreme value of the objective function is determined by means of the electronic computing device 24, and the operating point belonging to the determined extreme value is selected by means of the electronic computing device 24. In particular, the objective function is the temperature of the corresponding length region I, II, III that can be caused by the operating point, and the extreme value is the optimal value obtained by the minimum possible rotation speed and the minimum or maximum possible temperature of the corresponding length region I, II, III. Since the temperature control of the rotor shaft 5 in the embodiment shown in the figure is the cooling of the rotor shaft 5, the extreme value is the optimal value resulting from the minimum possible rotational speed and the minimum possible temperature of the corresponding length region I, II, III, so that in the embodiment shown in the figure, the objective function is minimized. As a result, the maximum possible cooling of the rotor shaft 5 can be achieved, and at the same time the minimum possible rotational speed of the pump 15, the minimum possible losses of the pump 15 and the maximum possible difference between the heat exchanger outlet temperature and the heat exchanger inlet temperature can be achieved, so that the optimal cooling of the rotor shaft 5 can be achieved in terms of the optimization problem.

[0046] For example, if the temperature control of the rotor shaft 5 is heating or warming of the rotor shaft 5, which can be heated, in particular, by making the oil flowing through the rotor shaft 5 have a higher temperature than the rotor shaft 5, then the extreme value is, for example, the optimal value resulting from the minimum possible rotational speed and the maximum possible temperature of the corresponding length range I, II, III. If the rotor shaft 5 is heated by means of oil, it is provided, for example, that the oil is heated by the heat exchanger 20. It is desirable that the heat exchanger outlet temperature (which is higher than the heat exchanger inlet temperature in this case) is as high as possible, so that the difference between the heat exchanger outlet temperature and the inlet temperature is also as large as possible. In this case, for example, the objective function is maximized, so that the optimal heating of the rotor shaft 5 can be achieved in terms of the optimization problem. On the one hand, the oil can be heated strongly by the heat exchanger 20, so that the oil flows into the rotor shaft 5 at an advantageously high shaft inlet temperature. On the other hand, the oil can be advantageously quickly, that is, advantageously at a high volume flow rate, through the rotor shaft 5, so that a large amount of heat can be input into the rotor shaft 5 per time unit through the oil, that is, transferred to the rotor shaft 5.

[0047] It can be seen that the method described allows a particularly effective and particularly efficient temperature control of the rotor shaft 5 .

[0048] For example, different length regions I, II and III of the rotor shaft 5 are depicted in or by the calculation model, so that optimal temperature control, in particular cooling, of the respective length region I, II, III can be selectively set for the length regions I, II and III. In this case, for example, the weighting or priority of the length regions I, II, III can be specified such that, for example, by selecting an operating point associated with a first cooling value, the length region I is optimally temperature controlled, in particular cooled, by selecting an operating point associated with a second cooling value, the second length region II is optimally temperature controlled, in particular cooled, by selecting an operating point associated with a third cooling value, and the length region III is optimally temperature controlled, in particular cooled, by selecting an operating point associated with a third cooling value.

[0049] Alternatively or additionally, the method can be used, for example, for targeted heating of the oil and thus of local areas and, for example, during a cold start, to resolve a conflict of objectives (the oil flows slowly through the rotor shaft 5 and quickly through the heat exchanger 20) by targeted heating of the oil. Thus, for example, the oil can be quickly tempered in order, for example, to minimize churning losses.

[0050] List of reference numerals:

[0051] 1 Motor

[0052] 2 Stator

[0053] 3 rotors

[0054] 4 Motor rotation axis

[0055] 5 Rotor shaft

[0056] 6 Temperature control device

[0057] 7 circuits

[0058] 8 temperature control channels

[0059] 9 Arrows

[0060] 10 Arrows

[0061] 11 Arrows

[0062] 12 Input pipeline

[0063] 13 Return line

[0064] 14 Flow Path

[0065] 15 Pumps

[0066] 16 conveying elements

[0067] 17 Pump housing

[0068] 18. Drive

[0069] 19 tanks

[0070] 20Heat exchanger

[0071] 21 Fluid circuit

[0072] 22 First Sensor

[0073] 23 Second sensor

[0074] 24 Electronic computing devices.

Claims

1. A method for temperature control of an electric drive unit of a motor vehicle having at least one electric machine (5), wherein: - a temperature control medium is conveyed through the flow path (14) by means of a pump (15), at least one partial region (I) of the drive unit is temperature controlled by means of the temperature control medium, and the pump (15) can be operated at different operating points with different volume flows of the temperature control medium; - a heat exchanger (20) is arranged in the flow path (14) upstream of the partial region (I) of the drive unit, through which the temperature control medium and another fluid, which are conveyed by means of the pump (15) and flow through the flow path (14), flow; - exchanging heat between the temperature control medium and the other fluid via the heat exchanger (20), thereby controlling the temperature of the temperature control medium; - calculating, by means of an electronic computing device (24), for a respective operating point at least one correspondingly associated cooling value, which cooling value characterizes a respective temperature of the subregion (I) of the drive unit, which temperature can be brought about by the respective operating point of the pump (15) to which the corresponding cooling value is assigned; - selecting one of the operating points according to the calculated cooling value by means of an electronic calculation device (24); and - The pump (15) is operated at the selected operating point with the aid of an electronic computing device (24).

2. The method according to claim 1, characterized in that: - using an electronic computing device (24) to create an objective function of the optimization problem as a function of the cooling value, the objective function of the optimization problem including the rotational speed of the pump (15) at the operating point as a parameter of the objective function; - determining at least one or exactly one extreme value of the target function by means of an electronic computing device (24); - Selecting an operating point belonging to the determined extreme value by means of an electronic computing device (24).

3. The method according to claim 2, characterized in that The target function is the temperature of the partial region (I) which can be brought about by the operating point, and the limit value is the optimum value resulting from the minimum possible rotational speed and the minimum possible or maximum possible temperature.

4. The method according to any one of the preceding claims, characterized in that At least one corresponding temperature value belonging to the respective operating point is calculated by means of an electronic computing device (24), which temperature value characterizes the respective supply temperature of the temperature control fluid provided by the heat exchanger (20) at the respective operating point, and a cooling value belonging to the respective operating point is calculated by means of the electronic computing device (24) based on the temperature value belonging to the respective operating point.

5. The method according to any one of the preceding claims, characterized in that The electric machine (1) comprises a rotor (3) having a rotor shaft (5).

6. The method according to claim 5, characterized in that At least one length region (I) of the rotor shaft (5) is used as the partial region (I).

7. The method according to any one of the preceding claims, characterized in that: - calculating, by means of an electronic computing device (24), for the respective operating point at least one respectively associated second cooling value, which second cooling value characterizes the respective temperature change of the second partial region (II) of the drive unit, which temperature change can be caused by the respective operating point of the pump (15) to which the respective second cooling value belongs; - selecting one of the operating points according to the calculated first cooling value and according to the calculated second cooling value by means of an electronic computing device (24); and - The pump (15) is operated at a selected operating point by means of an electronic computing device (24).

8. The method according to claims 7 and 5, characterized in that A first length region (I) of the rotor shaft (5) is used as a first partial region (I), and a second length region (II) of the rotor shaft (5) is used as a second partial region (II).

9. The method according to any one of the preceding claims, characterized in that A liquid is used as the temperature control medium.

10. The method according to any one of the preceding claims, characterized in that A liquid is used as the other fluid.

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