Method for operating a drive device of a motor vehicle, and corresponding drive device

Abstract

The disclosure relates to a method for operating a drive device of a motor vehicle, wherein the drive device has at least one heat-generating device and a cooling circuit for cooling the heat-generating device, and at least one first coolant cooler of the cooling circuit and at least one second coolant cooler of the cooling circuit are fluidically connected to the heat-generating device. It is thereby provided that the first coolant cooler and the second coolant cooler are fluidically connected in parallel to the heat-generating device, and that coolant arriving from the heat-generating device be divided by means of a control mechanism between the first coolant cooler and the second coolant cooler. The disclosure furthermore relates to a drive device of a motor vehicle.

Claims

1. A method, comprising: operating a drive device of a motor vehicle, wherein the drive device has at least one heat-generating device as well as a cooling circuit for cooling the heat-generating device, and at least one first coolant cooler of the cooling circuit and at least one second coolant cooler of the cooling circuit are connected in parallel with each other; and dividing coolant arriving from the heat-generating device by a final control element between the first coolant cooler and the second coolant cooler, wherein the coolant is divided between the first coolant cooler and the second coolant cooler as a function of a parameter selected from the group consisting of: a driving speed, a blower control, a cooling air mass flow, and a coolant volumetric flow of the motor vehicle.

2. The method according to claim 1, wherein the coolant is cooled by the first coolant cooler with a first cooling capacity and by the second coolant cooler with a second cooling capacity.

3. The method according to claim 2, wherein the coolant is divided between the first coolant cooler and the second coolant cooler such that a total cooling capacity resulting from the first cooling capacity and the second cooling capacity is at a maximum.

4. The method according to claim 1, wherein a manipulated variable for the final control element is determined using a technique selected from the group consisting of: a mathematical relationship, a characteristic map, and a closed-loop controller.

5. The method according to claim 1, wherein the coolant is divided between the first coolant cooler and the second coolant cooler at a first junction of the cooling circuit, and is merged at a second junction downstream of the first coolant cooler and the second coolant cooler.

6. The method according to claim 5, wherein a temperature difference of the coolant between the first junction and the second junction is used as a controlled variable for the final control element.

7. The method according to claim 1, wherein at least one control valve or at least one flow control valve is used as the final control element.

8. The method according to claim 1, wherein the at least one first coolant cooler has a higher rated cooling capacity than the at least one second coolant cooler.

9. A drive device of a motor vehicle, comprising: at least one heat-generating device as well as a cooling circuit for cooling the heat-generating device, at least one first coolant cooler of the cooling circuit and at least one second coolant cooler of the cooling circuit connected in parallel with each other; wherein the drive device is designed to divide coolant arriving from the heat-generating device between the first coolant cooler and the second coolant cooler by a final control element, wherein the coolant is divided between the first coolant cooler and the second coolant cooler as a function of a parameter selected from the group consisting of: a driving speed, a blower control, a cooling air mass flow, and a coolant volumetric flow of the motor vehicle.

10. The drive device according to claim 9 wherein the first coolant cooler has a first cooling capacity and the second coolant cooler has a second cooling capacity that is greater than the first cooling capacity.

11. The drive device according to claim 9, further comprising a first junction where the coolant is divided between the first coolant cooler and the second coolant cooler and a second junction where the coolant is merged from the first coolant cooler and the second coolant cooler.

12. The drive device according to claim 9 wherein the final control element includes a flow control valve.

13. A method, comprising: operating a motor vehicle having a heat-generating device; circulating a coolant through a cooling circuit to carry heat away from the heat-generating device; dividing the coolant carrying the heat away from the heat-generating device between a first coolant cooler having a first cooling capacity and a second coolant cooler having a second cooling capacity greater than the first cooling capacity based on a parameter of the operation of the motor vehicle to maximize the combined cooling capacity of the first coolant cooler and the second coolant cooler.

14. The method according to claim 13, wherein the dividing the coolant carrying the heat away from the heat-generating device between the first coolant cooler and the second coolant cooler is based on a difference between a first temperature of the coolant before being cooled by the first coolant cooler and the second coolant coolers and a second temperature of the coolant after being cooled by the first coolant cooler and the second coolant cooler.

15. The method of claim 1, wherein a third coolant cooler of the cooling circuit and the first coolant cooler are connected in series with each other.

16. The method of claim 15 wherein the first and third coolant coolers have a combined first cooling capacity and the second coolant cooler has a second cooling capacity greater than the first cooling capacity.

17. The drive device of claim 9 wherein a third coolant cooler of the cooling circuit and the first coolant cooler are connected in series with each other.

18. The drive device of claim 17 wherein the first and third coolant coolers have a combined first cooling capacity and the second coolant cooler has a second cooling capacity greater than the first cooling capacity.

19. The method of claim 13, wherein a third coolant cooler of the cooling circuit and the first coolant cooler are connected in series with each other.

Description

(1) The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without any limitation of the invention ensuing. Shown are:

(2) FIG. 1 a schematic of a region of a drive device of a motor vehicle, and

(3) FIG. 2 a diagram in which a total cooling capacity of two coolant coolers is plotted against a apportionment factor of coolant to the two coolant coolers.

(4) FIG. 1 shows a schematic of a region of a drive device 1 of a motor vehicle (not shown in detail). Of the drive device 1, a heat-generating device 2 is depicted which is preferably present in the form of a drive unit. The drive unit is, for example, designed as an internal combustion engine or as an electric motor. For cooling the device 2, a cooling circuit 3 is provided by means of which coolant may be supplied to the device 2. Insofar as it is discussed within the scope of this description that coolant is supplied to the device 2, such an embodiment may actually be realized or—alternatively—a heat exchanger may be associated with the device 2, to which heat exchanger the coolant is ultimately supplied. In this case, the heat exchanger is connected with the device 2 so as to transfer heat, so that the device 2 may be cooled by means of the coolant supplied to the heat exchanger.

(5) In addition to the device 2, at least one first coolant cooler 4 and at least one second coolant cooler 5, in the exemplary embodiment depicted here two second coolant coolers 5, are realized in the cooling circuit 3. The first coolant cooler 4 is designed as a main cooler, in contrast to which the second coolant coolers 5 are present as auxiliary coolers or secondary coolers. According to the arrows 6, the coolant coolers 4 and 5 may be charged with cooling air which preferably passes through the coolant coolers 4 and 5. The cooling air flows indicated by the arrows 6 are preferably induced by a blower of the drive device 1 and/or by a movement of the motor vehicle.

(6) The two coolant coolers 4 and 5 are fluidically connected in parallel to the device 2. The coolant arriving from the device 2 is hereby divided at a first junction 7 between the two coolant coolers 4 and 5 and reunited at a second junction 8. The first coolant cooler 4 is hereby fluidically connected to the first junction 7 on one side and to the second junction 8 on the other side. By contrast, the second coolant coolers 5 are connected in series with each other between the junctions 7 and 8. In other words, the second coolant coolers 5 are both present in parallel with the first coolant cooler 4. It is apparent that the second coolant coolers 5 are markedly smaller or more compact in design than the first coolant cooler 4. Accordingly, they have a lower rated cooling capacity than the first coolant cooler 4. In particular, their joint rated cooling capacity is less than or equal to the rated cooling capacity of the first coolant cooler 4.

(7) The drive device 1, or the cooling circuit 3, is designed such that the coolant arriving from the heat-generating device 2 may be specifically divided betweenst the first coolant cooler 4 and the second coolant coolers 5. For this purpose, a final control element 9 is provided which, in the exemplary embodiment shown here, is present in the form of a control valve. The control valve is hereby preferably designed as a 3/2-way valve, in particular as a 3/2-way continuously adjustable valve, so that the coolant can be distributed in any desired proportions amongst the coolant coolers 4 and 5.

(8) The coolant flowing through the first coolant cooler 4 is cooled with a first cooling capacity, and the coolant flowing through the second coolant cooler 5 is cooled with a second cooling capacity. A total cooling capacity of the coolant coolers 4 and 5 results from the first cooling capacity and the second cooling capacity. It is now provided that the coolant be divided between the coolant coolers 4 and 5 by means of the final control element 9 such that a greatest possible total cooling capacity results. For example, for this purpose the final control element 9 is set to divide the coolant between the coolant coolers 4 and 5 as a function of a driving speed of the motor vehicle. It is alternatively or additionally possible to set the final control element 9 to divide the coolant between the coolant coolers 4 and 5 as a function of a blower control and/or of a cooling air mass flow and/or of a coolant volumetric flow.

(9) A manipulated variable for the final control element 9 is here determined by means of a mathematical relationship, a characteristic map, or a closed-loop controller, for example. In the case of the closed-loop controller, the manipulated variable represents an output variable, in contrast to which a controlled variable forms an input variable. For example, a temperature difference is used as controlled variable, in particular a temperature difference between a temperature of the coolant at the first junction 7 and a temperature of the coolant at the second junction 8. The control objective is to maximize the temperature difference so that a greatest possible total cooling capacity of the coolant coolers 4 and 5 is accordingly realized.

(10) FIG. 2 shows a characteristic map in which a total cooling capacity in percent, relative to a maximum cooling capacity, is plotted against an apportionment factor. The different curves result for a cooling air mass flow through the coolants 4 and 5 which increases in the direction of the arrow 10. The apportionment factor indicates the proportion of the coolant which is supplied to the second coolant coolers 5. Given an apportionment factor of 0, the entirety of the coolant is thus supplied to the first coolant cooler 4, in contrast to which no coolant flows through the second coolant cooler 5. Given an apportionment factor of 1, the reverse applies, such that in this instance the entirety of the coolant flows through the second coolant cooler 5. Given an apportionment factor of 0.5, there is a uniform apportionment of the coolant between the coolant coolers 4 and 5.

(11) For each of the curves, the respective maximum of the total cooling capacity is indicated by a circle. It has been shown that the maximum of the total cooling capacity for increasing apportionment factors is present with increasing cooling air mass flow, for example caused by an increasing driving speed of the motor vehicle. Accordingly, the final control element 9 is set in such a way that this maximum of the total cooling capacity is achieved.

(12) With the described embodiment of the drive device 1, or of the corresponding procedure during its operation, the device 2 may be cooled particularly effectively and efficiently. In particular, an optimal total cooling capacity of the coolant coolers 4 and 5 is realized in each case for different operating conditions and/or different environmental conditions.