Method and device for controlling the thermal power of at least one cooling circuit of a motor vehicle

Abstract

The invention relates to a method (100) for controlling the thermal output of at least one cooling circuit (16) of a motor vehicle, wherein an electric drive (18) of the motor vehicle is integrated into a first cooling circuit (16). The method (100) comprises controlling (101) the thermal output of a cooling circuit as a function of a selection by a passenger of the motor vehicle after prioritizing a power output of the electric drive or the range of the motor vehicle. If the power of the electric drive is prioritized, additional thermal output is delivered to the electric drive in the form of cooling power, and if the range of the motor vehicle is prioritized, the electric drive is indirectly heated.

Description

[0001] The present invention relates to a method for controlling the thermal power of at least one cooling circuit of a motor vehicle, a corresponding device and a motor vehicle comprising a corresponding device according to the independent claims.

[0002] It is generally known from the prior art to supply thermal energy in the form of cooling power to an electric motor vehicle drive system using a cooling circuit. However, the prior art does not take into account customer-specific requirements for optimally utilizing the total available thermal power in terms of customer-specified range or performance requirements within the context of component protection.

[0003] From DE 10 2009 052 853 A1 a method is known for estimating the range of a motor vehicle with a quantity of energy carried and detectable in the motor vehicle, in which a driver sets a limit on a maximum permissible driving speed and / or a maximum permissible acceleration and / or a maximum power for a comfort system, the road profiles surrounding the motor vehicle, in particular an elevation profile or a road category, are recorded, a computer device calculates and displays a possible range at least on the basis of the limit set, the recorded road profiles and the quantity of energy still available.

[0004] From US 2017 / 0 045 133 A1, a vehicle drive device is known, comprising: an oil pump; an oil cooler; a bypass oil passage configured to bypass the oil cooler; a control valve; and a control unit. The control unit maintains the control valve in a first state while a temperature of the oil circulated by the oil pump is lower than a predetermined value, and switches the control valve to a second state when the temperature of the oil circulated by the oil pump does not become lower than the predetermined value while the control valve is in the first state. The control unit changes a voltage command value of an electric motor to a value lower than a voltage command value corresponding to a required power of the electric motor after a predetermined period of time has elapsed from the time the control valve is switched to the second state.

[0005] The present invention is based on the object of improving a method for controlling the thermal performance of at least one cooling circuit of a motor vehicle in such a way that customer-specific requirements are optimally taken into account in technical terms.

[0006] The aforementioned object is achieved by a method for controlling the thermal output of at least one cooling circuit of a motor vehicle. The motor vehicle is, for example, an electric vehicle or a hybrid vehicle. An electric drive of the motor vehicle is integrated into a first cooling circuit so that thermal energy, for example directly a cooling output or indirectly a heating output, can be supplied to it via the first cooling circuit. The method comprises controlling the thermal output for the electric drive as a function of a selection by a passenger of the motor vehicle after prioritizing a power output of the electric drive or a range of the motor vehicle, in particular an optional prioritization of a greater power output of the electric drive or a greater range of the motor vehicle.

[0007] In other words, the method may comprise providing a motor vehicle occupant with different options, according to which the occupant can select a preferred and thus prioritized electric drive performance or range. Depending on the selection, the thermal performance of a cooling circuit of the motor vehicle, in particular the first cooling circuit, is preferably controlled.

[0008] At least one second cooling circuit with a consumption unit (e.g., an oil pump) can be integrated into the first cooling circuit of the motor vehicle, with which thermal energy is exchanged via the first cooling circuit. Furthermore, all components of the motor vehicle to be cooled can be integrated into the first cooling circuit as consumption units. Each additional consumption unit is preferably assigned its own cooling circuit.

[0009] The minimum required total thermal power for component protection can be determined as follows: The minimum total thermal power for the consumer units to be cooled, excluding the electric drive, is preferably determined from the component specifications (especially the limit temperatures). The minimum cooling power for the electric drive, which results from the vehicle's specifications, can be added to this. The total is then the minimum required cooling power—in other words, the minimum required total thermal power—for component protection of all components of the vehicle to be cooled.If the currently available total thermal output of the vehicle's cooling circuit is greater than the cooling output currently required for component protection (including at least one consumption unit), the customer can select whether additional direct cooling output (for more power) or indirect heating output (for more range) can be made available to the electric drive.

[0010] The control of the thermal output, in particular of the first cooling circuit, can therefore be carried out depending on the currently available total thermal output of the cooling circuit to be controlled and / or depending on the minimum required total thermal output. The available total output can be compared with the currently available total thermal output of the cooling circuit to be controlled. The excess thermal output can then be used, depending on the occupant's selection, for further cooling of the electric drive and / or the at least one consumption unit and / or for heating the electric drive. The method thus ensures that component protection is always guaranteed and, in addition, that excess thermal output is optimally converted to meet the customer's selection for greater range or more power.

[0011] To determine the current minimum required total thermal power of the electric drive and the at least one consumer unit, the method can include measuring a temperature at the inlet and outlet of the electric drive and at the inlet and outlet of the consumer unit. This is done analogously for other consumer units to be cooled in order to protect their components. Using the corresponding temperature data, the current required total thermal power, in other words, the total thermal requirement, can be determined. The cooling medium is preferably water with a coolant.

[0012] If the power of the electric drive is prioritized, i.e. if a passenger selects accordingly, additional thermal power in the form of cooling power is delivered to the electric drive by means of the method, preferably by means of the first cooling circuit. This ensures that the electric drive can deliver the increased power. In particular, excess thermal power compared to the minimum required total thermal power can be delivered to the electric drive. In this regard, the method can comprise a change in the volume flow through the electric drive by means of a delivery unit of the first cooling circuit of the vehicle. A delivery unit can in particular be a pump, which is thus controlled as needed, i.e. according to the occupant's selection of more power or greater range.

[0013] The electric drive primarily comprises its own internal third cooling circuit, which, if necessary, can controllably exchange thermal energy with the vehicle's first cooling circuit via a bypass. This is primarily an oil circuit containing drive oil. The third cooling circuit can include its own delivery unit. Furthermore, the second cooling circuit of a consumer unit can also have its own delivery unit, whereby the second cooling circuit can also be connected to the first cooling circuit via a bypass. The vehicle's first cooling circuit can thus be a higher-level cooling circuit into which additional cooling circuits can be integrated.

[0014] If the range of the vehicle is prioritized, the electric drive is heated indirectly. The pumping capacity of the pump unit in the electric drive, in other words in the third cooling circuit, is preferentially reduced. This means that, firstly, the pump unit consumes less energy. Secondly, the previous cooling capacity in the drive is reduced in order to achieve a better thermal condition. Both effects increase the range. Here, too, thermal power, now indirectly as heating power, is transferred to the electric drive. By transferring heating power to the electric drive, the viscosity of the drive oil is reduced. This results in fewer so-called drag losses due to the movement of rotating components (rotor shaft, intermediate shaft, drive shaft, transmission gears) of the electric drive in the oil. In this way, an increased range can be achieved.

[0015] In addition to indirect heating by reducing the volume flow in the third cooling circuit of the electric drive, the heat transfer from the internal drive oil circuit to the first cooling circuit can alternatively or additionally be further reduced by a controllable bypass (e.g. via solenoid valves) in the first cooling circuit.

[0016] The method can comprise controlling a plurality of delivery units, in particular a delivery unit of the first cooling circuit and / or a delivery unit of the second cooling circuit of a consumer unit and / or a delivery unit of the third cooling circuit of the electric drive. With respect to each delivery unit, the method can comprise increasing the volume flow and / or reducing the volume flow of the cooling medium and thus increasing the temperature of the cooling medium, for example, for indirectly heating the electric drive. The delivery units can also deliver different cooling media.

[0017] The method can include multilateral balancing between the conveying units. This multilateral balancing primarily refers to the cooling capacity of the various conveying units in the different cooling circuits, although these units can also be balanced with each other with regard to the specified cooling capacity according to the corresponding control signals from a control unit. This allows, for example, the volume flow at the individual conveying units to be monitored in order to monitor and, if necessary, adjust the thermal performance of the various cooling circuits. This allows the thermal performance of each cooling circuit to be controlled separately.

[0018] In a further aspect, the invention comprises a device for controlling the thermal output of at least one cooling circuit of a motor vehicle, wherein the device comprises a control unit and is designed to carry out a method described above. Furthermore, the device can in particular also comprise an input unit by means of which a passenger of the motor vehicle can make a selection based on a prioritization of the output of the electric drive or the range of the motor vehicle. Furthermore, the invention relates to a motor vehicle with a cooling circuit, an electric drive, or a hybrid drive, and to a device as described above.

[0019] They show in purely schematic representation Fig. 1: a process diagram of a process according to the invention; Fig. 2: a device according to the invention. Fig. 3: another device according to the invention.

[0020] Fig. 1 shows a process diagram of a method 100 according to the invention, which includes controlling 101 the thermal power of at least one cooling circuit as a function of a selection by a motor vehicle occupant after prioritizing the power of the electric drive of a motor vehicle or the range of the motor vehicle. The method can include determining 102 a current minimum required total thermal power with respect to the electric drive and another consumption unit and further comparing this with the currently available total thermal power.If the currently available total thermal power exceeds the minimum required total thermal power, additional thermal power in the form of cooling power is delivered to the electric drive by means of a first cooling circuit 16 if the power of the electric drive is prioritized 103 or if the range of the motor vehicle is prioritized, the electric drive is heated 104.

[0021] Fig. 2 shows a device 10 according to the invention, comprising a control unit 11 and a delivery unit 12. Based on a selection by an occupant regarding a prioritization of power or range, the cooling circuit 16, into which the electric drive 18 and two further consumption units 17 are integrated, is controlled. Both consumption units 17 can comprise their own second cooling circuit. Furthermore, the electric drive can comprise a third cooling circuit belonging to the drive. The currently minimum required total thermal power 13 can be determined, and the control unit 11, taking this into account together with the occupant's selection for more range or more power, forwards a control signal 14 to a delivery unit 12. Based on this control signal 14, a controlled thermal power 15 of the first cooling circuit 16 is implemented by means of the delivery unit 12.In the right half of the image, a prioritization of performance 19 and a prioritization of range 20 are shown purely schematically as options.

[0022] In Fig. 3 shows a further device 10 according to the invention, which is analogous to the device for Fig. 2 is formed: The device 10 of the Fig. 3 comprises two conveyor units 12, namely a first conveyor unit 12a, which can be assigned to the first cooling circuit 16, and a second conveyor unit 12b, which can be assigned to the third cooling circuit. Both conveyor units 12 are controlled, the control being analogous to that shown in Fig. 2 is running, although a comparison 21 can take place between the conveyor units 12. List of reference symbols 10 Device 11 Control unit 12 conveyor unit 12a first conveyor unit 12b second conveyor unit 13 currently minimum required total thermal power 14 Control signal 15 controlled thermal power 16 first cooling circuit 17 Consumption unit 18 Electric drive 19 Performance Prioritization 20 Prioritizing reach 21 Comparison between conveyor units 100 procedures 101 Control of the thermal power of a cooling circuit depending on a selection of a passenger of the motor vehicle after prioritizing a power of the electric drive or a range of the motor vehicle 102 Determination of a current minimum required total thermal power with regard to the electric drive and at least one consumption unit 103 Delivering additional thermal power in the form of cooling power to the electric drive when prioritizing the power of the electric drive 104 Heating the electric drive when prioritizing the range of the vehicle

Claims

[1] Method (100) for controlling the thermal power of at least one cooling circuit of a motor vehicle, wherein an electric drive (18) of the motor vehicle is integrated into a first cooling circuit (16), wherein the method (100) comprises a control (101) of the thermal power of a cooling circuit for the electric drive (18) depending on a selection of an occupant of the motor vehicle after prioritizing a power of the electric drive or the range of the motor vehicle, characterized by that when the power of the electric drive (18) is prioritized, additional thermal power in the form of cooling power is delivered to the electric drive (18) and when the range of the motor vehicle is prioritized, the electric drive (18) is heated indirectly. [2] Method (100) according to claim 1, characterized by , that at least one further consumption unit (17) with a second cooling circuit is integrated into the first cooling circuit (16), wherein the method (100) comprises determining (102) a current minimum required total thermal power with respect to the electric drive (18) and the at least one consumption unit (17), wherein the control (101) of the thermal output of the cooling circuit is carried out as a function of a currently available total thermal output of the cooling circuit and / or the minimum required total thermal output. [3] Method (100 according to claim 2, characterized bythat the method (100) for determining (102) the current minimum required total thermal power with respect to the electric drive (18) and the at least one consumption unit (17) comprises measuring a temperature of the cooling medium at an inlet and an outlet of the electric drive (18) and at an inlet and an outlet of the consumption unit (17). [4] Method (100) according to one of the preceding claims, characterized by that the method (100) comprises changing the volume flow of the cooling medium through the electric drive (18) by means of a conveying unit (12). [5] Method (100) according to one of the preceding claims, characterized by , that the electric drive (18) comprises its own third cooling circuit, wherein the third cooling circuit is integrated into the first cooling circuit (16) and wherein a heat exchange between the third cooling circuit and the first cooling circuit (16) can be influenced by means of a bypass, wherein for indirect heating of the electric drive (18) the heat exchange is reduced by means of the bypass. [6] Method (100) according to one of the preceding claims, characterized by that the method (100) comprises controlling a conveying unit (12) for reducing the volume flow of the cooling medium of the first cooling circuit (16) and thus increasing the temperature of the cooling medium for indirectly heating the electric drive (18). [7] Method (100) according to one of the preceding claims, characterized by , that the method (100) comprises controlling a plurality of conveyor units (12), wherein the method (100) comprises a multilateral adjustment (21) of the conveyor units (12). [8] Device (10) for controlling the thermal power of at least one cooling circuit of a motor vehicle, characterized by that the device (10) comprises a control unit (11) and is designed to carry out a method (100) according to one of claims 1 to 7. [9] Motor vehicle comprising a cooling circuit (16), an electric drive (18) and a device (10) according to claim 8.

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