Patent Application
20230012900
The disclosure relates to an electrified drive train for a motor vehicle, having a heat generator, which comprises at least one electric drive machine and a cooling circuit, which is led through the electric drive machine and has a heat exchanger for removing heat from the cooling circuit. Furthermore, the disclosure relates to an electric vehicle having such an electrified drive train.
Electrified drive trains that are powered purely electrically instead of by an internal combustion engine are already known from the prior art. However, the prior art always suffers from the disadvantage that, especially in such purely electrically driven vehicles, the combustion engine is missing as a heat source and electric auxiliary heaters have to be used in order to be able to implement, for example, a comfort function, such as heating of the passenger compartment.
It is therefore the object of the disclosure to avoid or at least to mitigate the disadvantages of the prior art. In particular, an electrified drive train and an electric vehicle are to be provided in which, if possible, no auxiliary heaters are required, but other heat sources are used.
This object is achieved with a generic device according to the disclosure in that the heat exchanger in the cooling circuit, in particular in the cooling oil circuit, is arranged downstream of the heat generator to be cooled in the direction of flow of the fluid, preferably oil, used in the cooling circuit.
This provides the advantage that the waste heat from the heat generators to be cooled can be utilized by making the heat dissipated to a heat removal circuit, usually a water circuit, available to the vehicle. By arranging the heat exchanger downstream of the heat generator to be cooled, a greater proportion of the heat can be utilized as waste heat compared to a case where the heat exchanger is arranged upstream of the heat generator to be cooled in order to maximize cooling capacity. This means that existing heat sources are used for the heating function.
Advantageous embodiments are claimed and are explained below.
According to a preferred embodiment, the heat exchanger can be arranged directly downstream of the heat generator to be cooled. This advantageously ensures that as much of the waste heat from the drive train as possible is made available to the vehicle. By arranging the heat exchanger directly downstream of the heat generator, heat losses due to convection can be prevented or at least minimized.
In addition, it is advantageous if the heat generator is the electric drive machine or a secondary unit, such as a power electronics unit and/or a clutch and/or a gearbox. The electric drive machine in particular makes a large amount of waste heat available. The power electronics unit is also a large heat generator.
Furthermore, it is expedient if the drive train comprises several heat generators to be cooled, wherein the heat exchanger is arranged downstream of the heat generator to be cooled having the greatest heat generation. This ensures that as much waste heat as possible is made available for comfort functions such as a heating function for the vehicle.
Optionally, in addition to the heat exchanger arranged downstream of the heat generator having the greatest heat generation, a further heat exchanger can be arranged in the cooling circuit for dividing the cooling capacity, wherein the further heat exchanger is arranged upstream of the heat generator having the greatest heat generation. Thus, the cooling capacity is divided upstream and downstream of the main heat source so that the main heat source is advantageously both cooled sufficiently and can dissipate sufficient waste heat to the passenger compartment.
Furthermore, according to an advantageous further development, the heat exchanger can be arranged, preferably directly, upstream of the heat generators to be cooled, apart from the heat generator having the greatest heat generation. This provides the advantage that the cooling capacity is optimally utilized.
It is also useful if a volume flow of the cooling circuit is divided into partial volume flows which run parallel to one another. This means that the volume flow of the cooling circuit is at least partially parallelized. Preferably, anode of the cooling circuit where the volume flow is divided into the partial volume flows is located, preferably directly, downstream of the heat exchanger.
According to a preferred further embodiment, the volume flow can have a first partial volume flow for cooling the gearbox. Alternatively or in addition, the volume flow can include a second partial volume flow for cooling the clutch.
Furthermore, it is expedient if the cooling circuit has a hydraulic resistance arranged in the volume flow for adjusting the flow rate of the partial volume flows. Thus, the flow rate of the partial volume flows can be adapted to the heat generator to be cooled and arranged in the respective partial volume flow. This allows the cooling fluid to be supplied as required.
Preferably, the hydraulic resistance can be designed as an active adjusting element, i.e., an adjusting element controlled by an electric actuator, such as an e-magnet or an e-motor, or as a passive adjusting element, i.e., an adjusting element (fixedly) set based on the existing hydraulic control variables.
According to an advantageous embodiment, the drive train can have the cooling circuit led through the electric drive machine and a second cooling circuit led through the power electronics unit, wherein the heat exchanger of the cooling circuit is arranged downstream of the electric drive machine and a heat exchanger of the second cooling circuit is arranged downstream of the power electronics unit.
The object of the disclosure is also achieved by an electric vehicle having an electrified drive train according to the disclosure.
According to a second aspect independent of the first aspect of the disclosure, the disclosure also relates to an electrified drive train for a motor vehicle, comprising at least one electric drive machine, and a heat removal circuit having at least a first heat exchanger and a second heat exchanger for removing heat from a cooling circuit led through the heat generator, wherein, in operation, a fluid, preferably water, used in the heat removal circuit, in particular in the cooling water circuit, flows through the first heat exchanger and, in parallel therewith, through the second heat exchanger. In other words, according to the disclosure, at least partial parallelization of the flow of the heat removal circuit is proposed. This provides the advantage that, in particular, the problems that arise when several heat exchangers have to be flooded with cooling fluid/cooling water, such as a summation of the flow resistances as well as a sequence of the heat exchangers, can be solved. For example, with two e-drives, two power electronics units and two e-motors need to be cooled, so four heat exchangers would have to be flooded. If these heat exchangers were arranged sequentially, the order in which the water is heated, the residual cooling capacity for the sequential heat exchanger, and the summation of the flow resistances would have to be considered. Usually, such a sequential arrangement results in too high a load pressure for the pump. Due to the partially parallel flow according to the disclosure, the load pressure for providing the cooling water flow can be kept low, so that the power required for the pump (Q*p) is also lower and the range of the electric vehicle is less negatively affected. Correspondingly, in accordance with the disclosure, an advantageous design is proposed with respect to the flow resistances of the fluid/water through the heat exchanger, an interaction with the flow rate and the achievable cooling capacity.
According to a preferred embodiment, a volume flow of the heat removal circuit at a node can be divided into a first partial volume flow led through the first heat exchanger and a second partial volume flow led through the second heat exchanger. Alternatively, it is also possible to divide the volume flow of the heat removal circuit several times, i.e., to distribute it to more than two partial volume flows.
In an advantageous embodiment, the heat removal circuit can have a hydraulic resistance by means of which the division of the volume flow between the first partial volume flow and the second partial volume flow can be adjusted. In other words, it is proposed to provide an adjustable hydraulic resistance in the direction of flow in the node or downstream of the node of parallelization. This can avoid an undesired division of the volume flow and thus the cooling capacity. Such an undesirable division results from the fact that individual heat exchangers have different flow resistances, for example due to tolerances.
According to the advantageous embodiment, the hydraulic resistance can be a passive adjusting element/a passive valve arrangement. This makes it possible to realize a necessary division of the volume flow once during commissioning of the line/water path. A passive adjusting element is understood to mean that the adjusting element performs an adjusting action, such as limiting the flow rate, based on the existing hydraulic regulating variables, such as a flow rate. Such a hydraulic regulating variable can also be tapped from the cooling circuit led through the heat generator and fed to the adjusting element via corresponding hydraulic effective surfaces.
According to the advantageous embodiment, the hydraulic resistance can be designed as an active adjusting element/an active valve arrangement. By providing an active adjusting element, the volume flow can be adjusted as desired. Preferably, the volume flow can be adjusted by the active adjusting element depending on an operating state of the (electric) vehicle and/or an operating state of the electric drive machine. Thus, the volume flow can be divided asymmetrically by the parallelization, for example temporarily. Cooling efficiency can be increased as required due this control system. An active adjusting element is understood to mean that the adjusting element can be controlled by an electric actuator, such as an electromagnet or an electric motor.
In addition, it is preferred if the (active or passive) adjusting element is designed as a poppet, sieve or rotary slide valve. This allows a relatively simple and inexpensive adjusting element to be installed.
In a preferred embodiment, the drive train can have two electric drive machines, each having a power electronics unit and an electric motor, wherein a heat exchanger for the two power electronics units, i.e., for the cooling circuit led through the power electronics units, is arranged upstream of the node in the common volume flow.
In another preferred embodiment, the drive train can comprise two electric drive machines, each having a power electronics unit and an electric motor, wherein a heat exchanger for one power electronics unit, i.e., for the cooling circuit led through one power electronics unit, is arranged downstream of the node in the first partial volume flow, and a heat exchanger for the other power electronics unit, i.e., for the cooling circuit led through the other power electronics unit, is arranged downstream of the node in the second partial volume flow.
According to the preferred embodiment, the heat exchangers for the power electronics units, i.e., for the cooling circuit/cooling circuits led through the power electronics units, can be arranged upstream of the heat exchangers for the electric motors, i.e., for the respective cooling circuits led through the electric motor, in the direction of flow of the fluid.
According to a third aspect of the disclosure, the first aspect of the disclosure and the second aspect of the disclosure can also be combined. Thus, the disclosure also relates to an electrified drive train for a motor vehicle having a cooling circuit/cooling oil circuit design according to the disclosure and a heat removal circuit/cooling water circuit design according to the disclosure.
In other words, the disclosure relates to a particular heat exchanger assembly in the water cooling circuit and/or in the oil cooling circuit in vehicles having electric motors. In particular, therefore, the disclosure relates to a drive train having at least one e-drive. Similar to a drive train having an internal combustion engine, any loss of drive machines should be effectively removed for component protection and put to good use, for example, to increase the efficiency of the vehicle. Accordingly, in particular in a drive train having several electric drive machines, the cooling water circuit/heat removal circuit and the cooling oil circuit/cooling circuit are improved according to the disclosure.
In previous cooling (oil) circuits, a heat exchanger would typically be arranged upstream of the object/heat generator to be cooled so that the cooling fluid, such as oil, would be as cool as possible and thus the cooling capacity would be as high as possible. However, since (purely) electrically driven vehicles in particular lack the important source of heat provided by the combustion engine, electric auxiliary heaters must be used, for example to increase comfort inside the passenger compartment and to heat it. According to the disclosure, the heat exchanger is arranged in the cooling circuit in such a manner that the waste heat from the drive function can be used at least partially as a heat source or for the heating function. Accordingly, the heat exchanger (or the heat exchangers) is/are arranged downstream of the object/heat generator to be cooled in order to transfer as much heat as possible into a heat removal circuit. This heat can then be used for the vehicle's heating functions. In other words, the heat exchanger/cooler is arranged (directly) downstream of the main heat generator in order to prevent convection and to be able to supply as much of the waste heat from the drive train to the vehicle as possible.
In other words, the heat removal circuit/cooling (water) circuit according to the disclosure is concerned with the flow resistances of the water through the heat exchanger and the interaction with the flow rate and thus the achievable cooling capacity. In order to keep the load pressure for providing the cooling water flow and thus the required power as low as possible, it is problematic to have multiple heat exchangers—in the case of two e-drives, four heat exchangers for two power electronics units and two e-motors—sequentially flooded with cooling water, because the sequence of the heat exchangers and the summation of the flow resistances must be considered. According to the disclosure, an at least partial parallelization of the flow is proposed. However, due to tolerances, different flow resistances may result, which can lead to an undesired division of the cooling capacity. Therefore, an adjustable hydraulic resistance is provided downstream of the node of the parallelization in the direction of flow, which can be active, i.e., continuously adjustable, or passive, meaning initially adjustable.
The disclosure is explained below with the aid of drawings. In the figures:
The figures are only schematic in nature and serve only for understanding the disclosure. The same elements are provided with the same reference symbols. The features of the individual embodiments can be interchanged.
According to the disclosure, with respect to the direction of flow of the fluid used in the cooling circuit 4, in particular oil, the heat exchanger 5 is arranged in the cooling circuit 4 downstream of the heat generator 2 to be cooled. In the cooling circuit 4 shown in
The drive train 1 also has one or more secondary units. A secondary unit can be, for example, a power electronics unit 6 (cf.
In the embodiment shown, a volume flow 10 of the cooling circuit 4 is divided into partial volume flows that run parallel to one another. The oil is thus drawn from an oil sump 11, preferably via a suction filter 12, by a cooling pump 13. Then the oil of the volume flow 10 is conveyed by the cooling oil pump 13 through the drive machine 3. In the direction of flow behind it, the heat exchanger 5 is flooded. Downstream, the volume flow 10 is divided. A first partial volume flow 14 diverts from the volume flow 10 at a first node 15, which has a lower flow rate than the volume flow 10. Downstream, the volume flow is divided at a second node 16 into a second partial volume flow 17 and a third partial volume flow 18. The first partial volume flow 17 can, for example, be designed to cool the first clutch 7 and/or the second clutch 8. The first partial volume flow 17 can, for example, be designed to cool the gearbox 9. Preferably, the flow rate of the first partial volume flow 14 and the flow rate of the second partial volume flow 17 and the third partial volume flow 18 together are substantially equal.
A hydraulic resistance 19 is arranged in the volume flow 10 for adjusting the flow rate of the partial volume flows. In the embodiment shown, a hydraulic resistance 19 is arranged in each of the three partial volume flows 14, 17, 18. In the embodiment shown, the hydraulic resistance 19 is designed as a passive adjusting element 20. The hydraulic resistance 19 can also be designed as an active adjusting element, even though this is not shown in
Thus, according to the disclosure, the drive train 1 has the cooling circuit 4 led through the electric drive machine 3, in which the heat exchanger 5 of the cooling circuit 4 is arranged downstream of the electric drive machine 3.
The drive train 1 has the heat generator 2, comprising the at least one electric drive machine 3. In order to be able to remove the heat from a cooling circuit led through the heat generator 2, the drive train 1 has the heat removal circuit 25. The heat removal circuit 25 has at least a first heat exchanger 26 and a second heat exchanger 27 for removing heat from the cooling circuit. The cooling circuit can be formed, for example, by the first cooling circuit 4 and the second cooling circuit 21 shown in
According to the disclosure, the heat removal circuit 25 is designed such that, in operation, a fluid used in the heat removal circuit 25, such as water, flows through the first heat exchanger 26 and, in parallel, through the second heat exchanger 27. This means that a volume flow 28 of the heat removal circuit 25 is at least partially parallelized, i.e., divided into at least two partial volume flows. The volume flow 28 is divided at a node 29 into a first partial volume flow 30 and a second partial volume flow 31. At least one heat exchanger is arranged in each of the partial volume flows 30, 31 so that the heat exchangers are flowed through in parallel.
In the embodiments shown in
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
The embodiment shown in
The first heat exchanger 48 exchanges heat with a first cooling circuit 52. In the first cooling circuit 52, fluid, in this case oil, is conveyed by a cooling pump 53 to the first power electronics 6 and to the second power electronics 6. The second heat exchanger 49 exchanges heat with a second cooling circuit 54. In the second cooling circuit 54, fluid, in this case oil, is conveyed by a cooling pump 55 to the first drive machine 3, the first clutch 7 and the second clutch 8 of a double clutch and the gearbox 9. The third heat exchanger 50 exchanges heat with a third cooling circuit 56. In the third cooling circuit 56, fluid, in this case oil, is conveyed by a cooling pump 57 to the second drive machine 3, the first clutch 7 and the second clutch 8 of a double clutch and the gearbox 9.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 134 942.7 | Dec 2019 | DE | national |
| 10 2020 102 885.7 | Feb 2020 | DE | national |
This application is the U.S. National Phase of PCT Appln. No. PCT/DE2020/101021 filed Dec. 3, 2020, which claims priority to DE 10 2019 134 942.7 filed Dec. 18, 2019 and DE 10 2020 102 885.7 filed Feb. 5, 2020, the entire disclosures of which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2020/101021 | 12/3/2020 | WO |
